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Previously, Xu et al. reported that the combined application of biochar and phosphorus fertilizer in saline-sodic soil depicted a considerable decline in available P levels by accelerating phosphate precipitation/sorption processes owing to its high surface area and adsorption capacity . Hence, it can act as a sink rather than a P source for plants. Biochar modification by altering its surface area, pore size distribution, and functional groups, can increase or decrease its adsorption capacity for specific nutrients and help to regulate its selectivity for specific soil nutrients while reducing its affinity for others .
|
PMC11698939_p6
|
PMC11698939
|
Fate and limitations of biochar in agricultural soils
| 4.018628 |
biomedical
|
Study
|
[
0.9515433311462402,
0.000423315039370209,
0.04803338646888733
] |
[
0.9976413249969482,
0.00115685211494565,
0.0011471533216536045,
0.00005462010813062079
] |
en
| 0.999995 |
Previous studies enable us to refer that the capacity of biochar to adsorb essential nutrients such as nitrogen (N) or iron (Fe), sometimes surpasses the limits that are conducive to plant growth . If biochar adsorbs nutrients exorbitantly, it can lead to a reduction in their availability for plants, which can result in stunted growth or even plant death . Therefore, it is essential to carefully manage certain physicochemical characteristics to ensure that it does not have a negative impact on plant growth by competing with the plants for these essential nutrients. This can be achieved by using MB that has been specifically tailored to the needs of the soil and the plants being grown .
|
PMC11698939_p7
|
PMC11698939
|
Fate and limitations of biochar in agricultural soils
| 3.408613 |
biomedical
|
Study
|
[
0.8737764954566956,
0.0006089355447329581,
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] |
[
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] |
en
| 0.999995 |
Furthermore, the adsorption abilities of biochar can be selective and biased towards certain pollutants, which can affect the effectiveness of pesticides, the concentration of heavy metals, and even plant defense mechanisms . However, researchers are exploring ways to adjust the surface chemistry of biochar to improve the targeted removal of specific pollutants while minimizing any negative impacts on plant growth and defense .
|
PMC11698939_p8
|
PMC11698939
|
Fate and limitations of biochar in agricultural soils
| 2.184803 |
biomedical
|
Other
|
[
0.8047109842300415,
0.0009909545769914985,
0.1942981481552124
] |
[
0.12649963796138763,
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en
| 0.999999 |
The physicochemical characteristics of MB (Table 1 ) vary based on various alteration techniques, pyrolysis temperature, and the kind of feedstocks and modifying compounds (Table 2 ). This section discusses how different modification methods and agents improve the physical and chemical characteristics of MB . i. Surface Area and Pore spaces Table 1 Overview of essential characteristics of biochar Property Definition Reference Anion exchange capacity (AEC) The potential of biochar to adsorb anions Ash content These residues are non-combustible byproducts resulting from pyrolysis, originating from mineral and inorganic constituents of biochar Cation exchange capacity (CEC) The potential of biochar to adsorb cations Density Density refers to the mass of a substance divided by its volume, factoring in any spaces between particles. A lower density indicates a lighter weight per unit volume Electric conductivity It signifies the conductivity of a material, indicating its capacity to conduct electric current Elemental composition It represents the mole ratios of oxygen (O), carbon (C), hydrogen (H), nitrogen (N), and sulfur (S). Typically, the ratios of O/C and H/C moles are used as indicators of the degree of carbonization, where low ratios often indicate a higher stability of biochar Fixed carbon content The extent of carbonization can be inferred from the fixed carbon content, which is derived by subtracting the percentages of moisture, volatile matter, and ash from a given biochar sample. This calculation is expressed by the formula: FC (%) = [100 − (VM + Ash)] Heating value A metric denoting the utmost thermal energy accessible from complete combustion, often referred to as energy content, is defined as the heat produced per unit mass or per unit volume Hydrophobicity The attraction or affinity of biochar toward the water Mass yield An indicator of biochar production efficiency, denoting the ratio of the mass of pyrolyzed products to the mass of raw biomass pH-value An indicator of the alkalinity or acidity of biochar, expressed as pH, which is calculated using the formula pH = − log[H +] Pore volume and pore size distribution The cumulative volume of pores and voids within biochar defines its pore space. The distribution of pore sizes signifies the proportional occurrence of each pore size within the structure of biochar Porosity The ratio of the volumes of voids or pore space within a substance divided by the total volume of that substance is known as the porosity Specific surface area (SSA) The SSA of a substance, calculated as the total surface area per unit mass, serves as an indicator of both adsorption capacity and water retention ability in biochar Stability The percentage of original carbon content that remains following both abiotic and biotic degradation signifies the recalcitrance of the material in specific applications, such as carbon sequestration, under different conditions and time frames Surface functional group The functional groups found on the surface of biochar, such as carboxylic (-COOH), hydroxyl (-OH), amine, amide, and lactonic groups, enhance its sorption properties. These groups indicate the biochar's capacity to adsorb organic compounds and pollutants effectively, as well as its catalytic performance The functional groups present on the surface of biochar, including hydroxyl (-OH), carboxylic (-COOH), amine, lactonic, and amide groups, play a crucial role in enhancing their sorption properties. These groups are indicative of the biochar's ability to effectively adsorb organic compounds and contaminations, as well as its catalytic performance Water holding capacity The capacity of biochar to absorb and retain water Table 2 Overview of specific physicochemical characteristics of modified biochar used as a soil amendment Raw material Feedstock Activation Pyrolysis Temperature (°C) Modification Treatment SA (m 2 g −1 ) pH CEC (cmolc kg −1 ) C H O N Reference Plant Water hyacinth O 450 Post-treatment 32.48 10.3 3.53 46.7% – – 2.53% Fe 155.91 9.4 6.35 50.3% – – 3.57% Mn 34.34 9.4 3.73 47.6% – – 3.05% Zn 95.65 8.8 6.04 50.4% – – 3.14% Cu 62.11 9.4 3.93 49.1% – – 3.46% Pine chips HCl 400 Post-treatment - 2.5 17.4 608 g kg −1 – – 1,372 µg g −1 Peanut hull - 2.5 15.7 625 g kg −1 – – 1,8 µg g −1 Rice straw FeOS 300 Post-treatment 37.4 - - 37.4% 3.9% 0.8% 34.6% FeCl 3 40.9 - - 40.9% 4.7% 0.96% 30.8% Fe 38.5 - - 38.5% 3.4% 0.76% 23.6% Fe 3+ ( 1%) 500 Post-treatment 23.3 9.9 - 46.4% 2.8% 16.2% 2.23% Fe 3+ ( 5%) 26.4 5.7 - 43.8% 2.7% 15.8% 2.27% Fe 3+ ( 10%) 7.3 3.1 - 3.25% 2.5% 15.9% 1.72% FeCl 3 (1%) 14.6 10.2 - 45.5% 2.0% 11.2% 2.23% FeCl 3 (5%) 5.9 3.4 - 44.2% 2.1% 12.0% 2.32% FeCl 3 (10%) 5.7 3.1 - 44.1% 2.0% 13.8% 2.40% Corn stem Fe–Mn 600 Post-treatment 60.67 - - 72.6% 2.2% 4.7% 1.2% Platanus orientalis L Fe 650 Post-treatment 74.5 4.4 - 59.9% 0.9% – 2.2% Corn straws FeCl 3 600 Pre-treatment 4.1 2.5 - 38.0% 1.4% 27.7% 1.0% Rice hull NaOH 450 Post-treatment 396 6.5 3.2 77.9% 3.4% 15.7% 1.7% Cracking crop straws Commercial 500 - 22.9 8.3 – 414.7 g Kg −1 – – 14.36 g Kg −1 Rice straw Thiol 500 Post-treatment 0.34 2.3 – 43.7% 0.6% – – Wheat straw Mg 600 Post-treatment 292.5 – – 54.5% 2.3% 15.4% 0.5% Al 169.6 – – 46.8% 3.1% 16.9% 0.3% Mg–Al 268.5 – – 43.0% 2.0% 12.9% 0.4% Microbial 600 Pre-treatment 3.77 9.7 – 48.5% 5.8% – 0.6% Corn straw KMnO 4 600 Post-treatment 3.18 10.7 – 73.0% 0.7% 10.9% 0.3% Rice husks FeCl 3 600 Pre-treatment - 7.8 – 34.5% 1.0% 11.3% 0.3% Platanus orientalis L FeCl 3 650 Post-treatment 74.5 10.6 59.9 2.2 0.9 Carrot pulp Thiourea CH 4 N 2 S 550 Post-treatment – 9.1 59.18 47.2% 4.1% 23.2% 8.9% Cotton straws H 3 PO 4 500 Pre-treatment – – – 67.8% 4.1% 14.3% 0.11% NaOH – – – 68.2% 3.9% 6.5% 0.18% Corn straw Fe (NO₃)₃ 600 Post-treatment 207 9.8 1.0 68.0% 18% – 2.4% Animal Poultry manure Chitosan 450 Post-treatment 3.7 10.4 – 11.3% 1.2% – – Sheep manure 5.2 10.4 – 88.6% 1.0% – – Pig carcass FeCl 3 650 Post-treatment 18.4 10.6 30.8 1.3 2.1 CEC Cation exchange capacity, SA Surface area
|
PMC11698939_p9
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.407086 |
biomedical
|
Study
|
[
0.9969457983970642,
0.00046854064567014575,
0.0025856720749288797
] |
[
0.9907019138336182,
0.0006225108518265188,
0.008577927015721798,
0.00009767125447979197
] |
en
| 0.999996 |
The specific surface area (SSA) and pore structure of biochar play a significant role in adsorption and regulating the nature of biochar as hydrophilic or hydrophobic . The general purpose of modification in pristine biochar is to expand its surface area, which ultimately modifies its functional groups and enhances its magnetic performance and catalytic capacity . Many studies showed that pyrolysis temperature and functionalization with innovative materials can enhance the SSA and porous structure of biochar . Rong et al. observed a significant surge in surface area in pre-mixed banana peel biochar with Fe 2 O 3 after hydrothermal carbonization. Their results illustrated an increment of 407, 504, 451, and 446 m 2 g −1 by combining with 0.05–1.0 g of the precursor solution, respectively. Similarly, Park et al. reported that during high pyrolysis temperatures (500–600 °C), the volume of pores in sesame straw increased from 0.0716 to 0.1433 cm 3 g −1 .
|
PMC11698939_p10
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.095783 |
biomedical
|
Study
|
[
0.9891654849052429,
0.0004087952838744968,
0.010425752028822899
] |
[
0.995315432548523,
0.0002976471441797912,
0.004333246033638716,
0.00005366497134673409
] |
en
| 0.999998 |
Furthermore, in another research, it is depicted that the surface area of Saccharina japonica- derived biochar was positively influenced by the temperature, resulting in a notable increase (2.9–175 m 2 g −1 ), with the highest surface area achieved at 500 °C noted that ZnCl 2 − EBcan enhance the pore size up to 0.2–0.9 cm 3 g −1 . The BET (Brunauer, Emmett, and Teller) approach is frequently used to determine the SSA of biochar. In this method, the amount of N 2 adsorbed on the surface of the biochar is evident at low temperatures (77 K) . Apart from modification by nano-scale zero-valent iron and the effects of pyrolysis temperature, the subsequent impregnation of biochar with Mn or Mg enhances the surface area from 209.6 to 463.1, 12.68 to 174.29, and 244 m 2 g –1 , respectively .
|
PMC11698939_p11
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.160274 |
biomedical
|
Study
|
[
0.9949700236320496,
0.0003093376290053129,
0.004720707889646292
] |
[
0.9990140199661255,
0.00022161049128044397,
0.0007320379372686148,
0.000032302170438924804
] |
en
| 0.999998 |
On the contrary, several studies have documented a decrease in the SSA of functionalized biochar. The decline in surface area could potentially be attributed to the pore openings or pores being obstructed by chitosan . Recently, manganese oxide activation revealed a considerable decrease in SSA ranging from 60.97 to 3.18 m 2 g −1 . Another research found that functionalized biochar through sulfur significantly affected surface area in contrast to pristine biochar. The highest surface area was observed in biochar generated at 500 °C and 700 °C (382 and 404 m 2 g −1 ), whereas functionalization with sulfur led to a significant reduction in surface area to 10.06 m 2 g −1 and 5.10 m 2 g −1 . Hence, it is crucial to thoroughly evaluate the characteristics of the final product concerning the impact of the modification process. ii. Elemental Composition
|
PMC11698939_p12
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.086975 |
biomedical
|
Study
|
[
0.9738590121269226,
0.000410063483286649,
0.025730982422828674
] |
[
0.9987437129020691,
0.00037678852095268667,
0.0008423609542660415,
0.00003713584374054335
] |
en
| 0.999996 |
Generally, the pristine biochar comprises 2–5% H, 45–60% C, and 10–20% O. Although the individual components employed to develop the product vary widely and rely on the feedstock. In order to assess the degree of hydrophobicity and carbonization in biochar, researchers commonly employed the O/C and H/C molar ratios . Additionally, it includes minerals, such as Si, P, Ca, Al, and K, that are prominent inorganic components of biochar . Many studies highlighted that type of feedstock, pyrolyzing procedures and functionalization may modify the properties of pristine biochar . In one study, Mn-oxide-MB illustrated a surge in O (10.9%) and Mn (7.41%) concentrations. Meanwhile, similar research observed that C, H, and N levels declined from 85.3–73.0%, 1.75–0.33%, to 0.80–0.72% . This reduction was attributed to the activation process wherein previously MB was exposed to additional high temperatures, leading to the further breakdown of C, H, and N and their conversion into ash .
|
PMC11698939_p13
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.183298 |
biomedical
|
Study
|
[
0.9617998600006104,
0.00047781411558389664,
0.03772233799099922
] |
[
0.9976254105567932,
0.0004597999795805663,
0.0018696843180805445,
0.00004520478250924498
] |
en
| 0.999998 |
Furthermore, Wu et al. also reported a decline in H and C contents when biochar was magnetically modified with FeOS, Fe, and FeCl 3 . In FeOS biochar, C and H contents were the highest at C at 12.65% and 1.23%, while the lowest was in FeCl 3 -engineered at 9.16% and 0.28%, respectively. In addition to the mentioned modifications and their effects on the elemental constitution of biochar, various additional substances, such as chitosan and alkali/acid, have also demonstrated beneficial outcomes. Chitosan amendment resulted in a lower C percentage and increased H, O, and N ratios, confirming the inclusion of treated material on the surface of biochar . iii. Alkalinity and pH
|
PMC11698939_p14
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.057669 |
biomedical
|
Study
|
[
0.9326537847518921,
0.00042609855881892145,
0.0669201985001564
] |
[
0.9982705116271973,
0.0008193052490241826,
0.0008648040238767862,
0.00004539932342595421
] |
en
| 0.999997 |
The pH of typical biochar usually varies from neutral to alkaline and is highly dependent on the type of feedstock, thermochemical process, and functional material, while studies about acidic biochar are also present . During the high pyrolysis temperature, the acidic functional groups (bionic acid) decompose, elevating the pH of biochar and causing an increase in inorganic alkali metal ions . Additionally, several organic functional groups, including –COOH, –COO, –O, and –OH, can similarly raise the pH of biochar .
|
PMC11698939_p15
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 3.309076 |
biomedical
|
Study
|
[
0.6831917762756348,
0.0004786420613527298,
0.31632956862449646
] |
[
0.8665969371795654,
0.1304466426372528,
0.002715607639402151,
0.00024082351592369378
] |
en
| 0.999997 |
In another study, Zhou et al. recorded pH values of different biochars prepared from bamboo (7.9), sugarcane bagasse (7.5), hickory wood (8.4), and peanut husk (6.9), but after chitosan modifications, pH values changed to more alkaline 8.2, 8.1, 8.6, and 7.3, respectively. Similarly, the pH of corncob biochar produced at 600 °C was shown to be neutral (7.17), but after being modified by Mg-oxide, it reduced considerably to 10.4 . On the contrary, FeCl 2 -impregnated biochar exhibited an acidic characteristic (4.87) contrasted to conventional biochar (10.7) .
|
PMC11698939_p16
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.054538 |
biomedical
|
Study
|
[
0.979721188545227,
0.00031783280428498983,
0.01996106654405594
] |
[
0.9978371262550354,
0.00042590152588672936,
0.0017004418186843395,
0.00003652288069133647
] |
en
| 0.999996 |
Moreover, hydrophilicity, hydrophobicity, sorption, and adsorption can be influenced by organic groups and linked with the buffering action of acid and base. Additionally, the organic groups present on the biochar surface carry negative charges, increasing the CEC . As the CEC of biochar increased, it ultimately surged in adsorption capacity . Biochar modification by surface oxygenation via dry ozonization proved a promising technique for enhancing the CEC 10 times, in contrast to conventional biochar . For instance, biochar derived from the limb of a pine tree and subjected to ozone gas for 1.5 h, the CEC of the biochar considerably elevated from 15.39 cmol kg −1 to 32.69 cmol kg −1 . Although this technique decreased the pH and demonstrated the oxygenic functional group formation of the biochar surface . iv. Functional Groups and Aromaticity
|
PMC11698939_p17
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.145008 |
biomedical
|
Study
|
[
0.9916977882385254,
0.00024870081688277423,
0.008053481578826904
] |
[
0.9987799525260925,
0.0007973054889589548,
0.0003858713898807764,
0.00003688348442665301
] |
en
| 0.999997 |
Several functional groups are associated with the surface of biochar, such as carboxylic, hydroxyl, and phenolic functional groups that contribute significantly to the remediation of contaminated soils . Among them, the most prevalent are O-containing functional groups, which can additionally be classified into neutral, and alkaline groups according to their inherent characteristics. The carboxyl, lactonic, and phenolic groups are examples of acidic groups, while the chromene and pyrone groups are known as basic active sites . Their characteristics may be related to the carbon’s surface basic nature, which is more evident in carbon atoms without oxygen because of the existence of delocalized electrons .
|
PMC11698939_p18
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 3.949141 |
biomedical
|
Study
|
[
0.8991094827651978,
0.00035051078884862363,
0.10053998976945877
] |
[
0.9496011734008789,
0.04152211174368858,
0.008735972456634045,
0.00014074590581003577
] |
en
| 0.999994 |
The pyrolysis temperature significantly influences the functional groups present on the biochar surface. It is found that C=C and –CH 2 functional groups could be successfully retained in pyrolysis, although C–O–C and –OH, C=O functional groups reduced with increasing pyrolysis temperature . Meanwhile, biochar’s water affinity, CEC, and polarity are regulated by oxygen-containing surface functional groups . Generally, the yield of biochar declines, while on the contrary, alkaline functional groups, pH, and ash concentration increase with increasing temperature . In a recent study, the adsorption capacity of MB derived from rice straw was observed to be higher than that of cotton straw-MB, likely due to the presence of additional functional groups .
|
PMC11698939_p19
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.116367 |
biomedical
|
Study
|
[
0.9791162610054016,
0.0003832765796687454,
0.02050042897462845
] |
[
0.9992820620536804,
0.00034949503606185317,
0.00033528925268910825,
0.00003316828951938078
] |
en
| 0.999994 |
The aromatic π-system is known to be involved in significant types of noncovalent specialized engagements termed electron donor–acceptor (EDA) interactions . The aromatic structures of biochar can significantly enhance pollutant adsorption, as they act as electron donors or acceptors and create bonds with the pollutants in soil . Usually, the carboxyl functional groups on the surface of carbonaceous adsorbents serve as electron acceptors, whereas the hydroxyl groups behave as electron donors . The aromaticity of biochar, determined using O/C and H/C ratios is highly influenced by pyrolysis temperature. The biochar derived from plant residues contains higher aromaticity due to high carbon material concentration. The cellulose and lignin decompose into small molecules that ultimately reduce H/C and O/C ratios as a result of depolymerization or dehydration. On the other hand, biochar from animal fecal and sludge does not possess any lignocellulosic molecules and hence avoids the depolymerization process .
|
PMC11698939_p20
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.19662 |
biomedical
|
Study
|
[
0.9929331541061401,
0.00024908658815547824,
0.00681783352047205
] |
[
0.9990749359130859,
0.0005715357838198543,
0.00032159037073142827,
0.000031997249607229605
] |
en
| 0.999997 |
In a recent sulfamethoxazole structural analysis research, it was observed that the N-heteroaromatic ring, unprotonated sulfonamide group, and amino functional group act as significant π -electron acceptors, although they possess a high capacity to donate electrons . Similarly, Zhao and Zhou also reported π − π EDA interactions between biochar aromaticity and sulfamethoxazole. However, potential electron-donating groups identified include the phenolic −COOH−C−O and −OH groups . v. Hydrologic Properties
|
PMC11698939_p21
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.143707 |
biomedical
|
Study
|
[
0.9992805123329163,
0.0001622304698685184,
0.0005572751979343593
] |
[
0.9988590478897095,
0.00041757835424505174,
0.000677426578477025,
0.000046008877689018846
] |
en
| 0.999997 |
The ability of MB to resist water is a crucial quality that has a significant impact on soil water retention . But the water retention property of biochar is highly dependent on the source of feedstock, synthesis technique, wetting characteristics, and particle size . The temperature during pyrolysis significantly influences the hydrologic characteristics when biochar is applied to soils . The most favorable hydrologic qualities were reportedly found in acid-functionalized biochar generated at higher temperatures (400–600 °C); in such amendment, water holding capacity was 18.45–22.45% higher than the control. This surge in water retention can be a result due to (i) high surface area and pore spaces and (ii) more hydrophilic functional groups that aid functionalized biochar . Besides, Zn (23.85%) and Fe (22.45%), impregnated biochars also exhibited a considerable increase in water-holding capacity in soil against soil gravity losses —the mineral formation of Fe and Zn aids in water retention by increasing chemisorption and physisorption. For instance, hematite surfaces possess the capacity to sorb water 23–24 A 2 per molecule, allowing it to adsorb the polar water molecules . In contrast, the hydrologic properties of biochar are found to be independent of soil types, such as coarse-grained (non-cohesive) soil or fine-grained (cohesive) soil . The mechanical resilience of aggregates at both micro and macro-scales was enhanced in biochar-amended soils, leading to notable improvements in cohesion and compressive behavior . There are possibilities that the hydraulic characteristics of soil that have been treated with EB extensively correlate with the quality and content of biochar, but these interactions are inadequately understood . vi. Complexation and Van der Waals forces
|
PMC11698939_p22
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.265081 |
biomedical
|
Study
|
[
0.8922939300537109,
0.0010960318613797426,
0.10660997033119202
] |
[
0.9953868985176086,
0.0011375682661309838,
0.003380067180842161,
0.00009549235255690292
] |
en
| 0.999997 |
Complexation is a special ability of biochar for adsorption that indulges ligand exchange, and bridging ligands are used to transport electrons . The electron donors and acceptors engage to produce different compounds during the surface complexation. During the formation of these surface compounds, several polyatomic structures significantly improve the sorption potential of biochar . Besides, chelation is an exceptional kind of complexation that is described as an equilibrium process and distinguished by the development of a complex between organic molecules with more than one functional group (multiple bounds) and a single central atom .
|
PMC11698939_p23
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 3.91487 |
biomedical
|
Study
|
[
0.9011380076408386,
0.00046801072312518954,
0.09839393198490143
] |
[
0.8035069704055786,
0.18614435195922852,
0.010069512762129307,
0.0002791514270938933
] |
en
| 0.999997 |
Several biochar features indicated that it may be an extremely effective adsorbent for the majority of soil contaminants and metals. Although these properties are highly influenced by the source of feedstock, pyrolysis time, and temperature, sufficient consideration should emphasize the analysis techniques of biochars produced under different circumstances.
|
PMC11698939_p24
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 1.79575 |
other
|
Other
|
[
0.26905393600463867,
0.0010218507377430797,
0.7299241423606873
] |
[
0.1651323437690735,
0.8294849395751953,
0.004525066819041967,
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en
| 0.999997 |
The functionalized biochar contains a larger surface area and more functional groups than pristine biochar, such as carboxylic, phenolic, and lactonic functional groups that act as electron acceptors while the product of low pyrolysis possesses more electron-donating functional groups including amino –NH 2 and hydroxyl –OH . The complexion potential of biochar can improve if it is pyrolyzed in the presence of oxygen because of more surface oxidation. It is observed that plant-derived engineered biochars have higher complexion capacities for heavy metals in soils as compared to poultry litter and dairy manure-derived biochars .
|
PMC11698939_p25
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 3.934041 |
biomedical
|
Study
|
[
0.924852192401886,
0.00034515210427343845,
0.0748026892542839
] |
[
0.9872554540634155,
0.010988387279212475,
0.001676018931902945,
0.00008009185694390908
] |
en
| 0.999995 |
The van der Waals forces, also known as hydrophobic interactions, refer to intermolecular interactions that bind molecules together. These interactions are divided into two types: (i) weak London dispersion forces and (ii) stronger dipole–dipole forces . The van der Waals forces possess relatively modest energy about 0.4–4 kJ mol −1 ), while most of the sorbates are associated with biochar nonspecifically (weak London dispersion forces) . These forces specifically contribute to interactions between carbonaceous sorbents and ionic organic compounds because of the larger molecular size of IOCs as van der Waals forces increase with increasing contact area, and the high van der Waals coefficient of activated carbon (graphite) .
|
PMC11698939_p26
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.180408 |
biomedical
|
Study
|
[
0.9976257681846619,
0.0001741649757605046,
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] |
[
0.996884286403656,
0.0025026449002325535,
0.0005619291914626956,
0.000051025817811023444
] |
en
| 0.999996 |
It is noted in a study that ZnCl 2 -MB enhanced the pore size up to 0.2 cm 3 g −1 to 0.9 cm 3 g −1 and the adsorption capacity of biochar via van der Waals forces . Similarly, montmorillonite-biochar composites pyrolyzed at 400 °C were also found to be highly effective for ammonium adsorption via Van der Waals interaction . Usually, the adsorption of organic pollutants on biochar occurs via weak physical adsorption without any strong chemical bonding. These weak bonds include hydrogen bonding, van der Waals forces, hydrophobic interactions, and electrostatic forces .
|
PMC11698939_p27
|
PMC11698939
|
Physicochemical characteristics of modified biochar
| 4.077559 |
biomedical
|
Study
|
[
0.9826645255088806,
0.0002573177916929126,
0.017078110948204994
] |
[
0.9967723488807678,
0.0014316014712676406,
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0.000050847749662352726
] |
en
| 0.999996 |
The flexibility and interaction of biochar with soil are highly influenced by its various physical and chemical characteristics. Hence, a deep structural and physical analysis via appropriate methods has been proven beneficial . If left unaddressed, the presence of a non-carbonized layer may lead to fluctuations caused by soil contaminants or other materials, potentially yielding inaccurate results . A detailed summary of the physicochemical attributes of the MB employed in soil, along with a comprehensive overview of the advantages and disadvantages of the analytical techniques, is presented in Table 3 . Table 3 Summary of various analytical techniques of modified biochar Technique Utilization Advantages Limitation Evaluated Biochars Reference Scanning Electron Microscopy (SEM) • It is used to determine morphological differences between biochar surfaces and pores arrangement • Limited need for conductive coatings due to high gas pressure • High magnification can be obtained in a range between 300000x and 500000x • Not applicable for organic contaminants • Magnetic biochar (γ-Fe 2 O 3 ) • Magnetite (Fe 3 O 4 ) biochar • MgO biochar nanocomposites Energy Dispersive X-ray (EDX) • It can evaluate the biochar surfaces and mapping of abundant elements • Have the potential to precisely identify and assess the arrangement and existence of elements in the scanned domain • High-speed data collection and processing • Easy to handle • Only detect the elements that have higher atomic numbers than boron • Highly dependent on probe current and voltage • Not applicable for organic contaminants • S, Mn and Fe MB • Magnetic biochar (γ- Fe 2 O 3 ) Transmission Electron Microscopy (TEM) • TEM is used to determine the surface morphologies like SEM • It can also analyze the lattice constant and chemical composition of biochar • Very High magnification can be obtained in the range between 200000 and 1000000x • A multifunctional instrument that can be used for spectroscopy and nanoscale imaging • It requires a high degree of vacuum to restrict the electron scattering they travel from the electron source to the electron optics • Fe 3 O 4 Biochar • Biochar nanoparticles (wheat straw) X-ray Diffraction (XRD) • It can analyze the composition of biochar, such as crystalline C or other materials • It is also used to determine organic compounds, including cellulose, hemicelluloses, and lignin, as well as inorganic compounds, such as oxides and sulfides carbonates • A non-destructive technique that can produce 3D characterization of interface structure • It can be used with different combinations of in-situ methods • In-situ methods and Time resolution is possible • Requires high-intensity X-ray beam • The usage is limited to access time to synchrotron source and single crystal surfaces • S and Fe 3 O 4 -MB X-Ray Absorption Near Edge Structure (XANES)/ Near Edge X-Ray Absorption Fine Structure (NEXAFS) • XANES/NEXAFS used to investigate the surface chemistry of highly complex types of C materials, for instance, charcoal • It can be used to identify the C species and stability with several structures at different pyrolysis time intervals (100–700 °C) • Direct structural determination of any matter and isotope • Oxidation state and spin state direct determination • Spectroscopy carried out in bulk gives an average structure • Very little information about the angle of the structure determines • Synchrotron X-ray source required • Fe- EB • KOH steam–activated pecan shell biochar X-ray photoelectron spectroscopy (XPS) • It is effective for surface characterization of biochar (surface elemental composition) • It can analyze chemical bonds, chemical, and the presence of distinct species of elucidated compounds on the surface of biochar • It can carry sensitive surface quantitative analysis such as material composition and empirical formula (without hydrogen) • Have the potential to analyze the material up to the depth of 1–10 nm • This technique is only applicable to solids since a high vacuum is needed • Highly time-consuming and cannot recognize hydrogen and helium atoms • FeCl 3 , FeSO 4 , Fe/Ca, and Mn EB • MnO/NiO biochar composite Fourier‐transform infrared spectroscopy (FTIR) • It can investigate mineralogy and chemical functional groups of biochar • Variation in the carbonation degree also makes it possible to determine • The analysis can be performed on any matter (solid, liquid, or gas) • Fast and non-destructive data acquisition and processing • Mapping with a good special resolution of large surface samples is possible • The interpretation of data is difficult, especially when working with a complex matter • Aqueous mixtures are complicated to investigate because water has a high infrared absorption capacity • DOM/Cu MB • Fe/Mn EB Raman spectroscopy • This technique is effective in quantifying the structural characteristics, especially graphite structures of biochar • Functional groups and crystalline C structures can be evaluated as well • A precise single-point assessment carried out with an excellent special resolution • Spectra possess quantitative and qualitative information • It is feasible to acquire insight into the functional groups in the polymer • Measurement parameters variation may affect the signal (e.g., laser wavelength) that negatively affects data interpretation • Fe/Ca-EB • (NH 4 ) 3 PO 4 impregnated biochar • Magnetic biochar (γ-Fe 2 O 3 ) X-ray fluorescence spectroscopy (XRF) • Commonly utilized to evaluate the compounds of biochar • Determination of inorganic compounds present on the surface of biochar • Very effective in quantifying the composition of biochar • More powerful and precise for inorganic materials determination as compared to XRD • Very costly • Fe-EB • N and O activated Solid-state nuclear magnetic resonance (NMR) • The structural composition of biochar and carbonization degree and stability can be determined by this method • It can be used to evaluate the contents of functional groups such as aromatic hydrocarbons, phenolic, methoxyl, and aliphatic in a biochar • Findings for stability have strong correlations with several other techniques • It gives deficient signals/noise ratio when encountering with high temperature pyrolyzed biochar • Signals obscured in the presence of ferromagnetic materials • NaOH- MB • CO 2 and steam-activated biochar • N and O activated biochars
|
PMC11698939_p28
|
PMC11698939
|
Analytical techniques for modified biochar
| 4.21181 |
biomedical
|
Study
|
[
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[
0.9057533144950867,
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0.09137329459190369,
0.00016185539425350726
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en
| 0.999997 |
Modified biochar (MB) can alter soil functional groups, pore size, pore structure, surface area, and chemical properties. These modifications significantly impact soil quality by influencing its physical and hydraulic properties, nutrient profile, gas exchange characteristics, organic matter content, pH, electrical conductivity (EC), cation exchange capacity (CEC), and biological activities, including those of bacteria, fungi, and enzymes. The following provides a brief overview of how the addition of MB as a soil amendment affects soil quality. i Soil pH
|
PMC11698939_p29
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 1.944918 |
other
|
Other
|
[
0.05659398064017296,
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[
0.29388946294784546,
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0.0022980603389441967
] |
en
| 0.999997 |
The presence of hydrogen (H + ) and aluminum (Al 3+ ) ions in the soil exchangeable sites causes acidity, severely affecting crop yield . Pristine biochar is primarily alkaline in nature . The pyrolysis temperature (> 400 ℃) produced biochar with alkaline pH . When applied to soil, organic compounds on the biochar surface will dissolve in water entering the pore spaces, increasing soil pH . Also, biochar increases the sorption of nutrients and decreases acidity in acidic soils . However, the effectiveness of biochar in changing soil pH in acidic soils depends on the composition, properties of feedstock, and pyrolysis temperature . Thus, several modifications of biochar have been developed. The activation of rice hull biochar by immersing with dimethyl dithiocarbamate sodium solution effectively decreased pH from 10.28 to 6.53 and improved soil properties . The application of Fe-MB in Cd-contaminated soils slightly increased pH units from 7.83 to 7.93 and helped to immobilize Cd in soil . In the case of red soils, the manganese-oxide-MB increased soil pH by 1.4 units while only 0.4 units increased in pristine biochar, thus preventing acidification in red soils . On the other hand, the pH of As-contaminated paddy soils (pH 7.12) were markedly decreased by Fe–Mn MB by around 0.75–1.16 units compared to the control . Similarly, It was observed that soil resistance to acidity was enhanced through the application of HNO 3 /H 2 SO 4 -MB . Furthermore, thiourea-modified poplar-bark biochar was applied to Cd-contaminated soil, resulting in a 17% increase in soil pH as compared to the control, which led to an increase in base cations in the soil . In multi-polluted soils, the magnetic biochar derived from eucalyptus wood and poultry litter increases soil-surged pH by 0.2–0.3 units . Likewise, the porous magnetic biochar from wheat straw was added to the soil and increased soil pH by approximately 6% . But in calcareous soils, steam-AB (acidic biochar) effectively decreases soil pH by 0.2–0.4 units , while in As-contaminated soil, Ca-MB causes an increase in pH .
|
PMC11698939_p30
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 4.245667 |
biomedical
|
Study
|
[
0.930526614189148,
0.0010865980293601751,
0.0683867335319519
] |
[
0.980414628982544,
0.0009886163752526045,
0.018473656848073006,
0.00012308135046623647
] |
en
| 0.999996 |
In contrast, rice straw MB with a 1:1 mixture of HNO 3 /H 2 SO 4 and 15% H 2 O 2 effectively improved pH buffering capacity and resistance to soil acidification compared to HCl-treated and unmodified biochar. The enhanced resistance was attributed to surface functional groups that increased soil resistance to acidification by generating protonation of organic anions, which retarded the decline in soil pH. However, HNO 3 /H 2 SO 4 MB showed a higher number of carboxyl functional groups compared to the 15% H 2 O 2 -modified biochar, resulting in greater resistance to soil acidification. The application of HNO 3 /H 2 SO 4 MB in paddy soil increased pH after wet-dry cycles, suggesting that this modification is an effective solution for remediating acidic soils. The underlying mechanism involves weak acid functional groups on the biochar surface that exist as organic anions in alkaline and neutral soils. Under acidic conditions, these anions protonate with H + and convert to neutral molecules, inhibiting soil acidification and preventing a decline in soil pH ,
|
PMC11698939_p31
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 4.201375 |
biomedical
|
Study
|
[
0.975844144821167,
0.0007574342889711261,
0.02339841239154339
] |
[
0.9988364577293396,
0.0003741029358934611,
0.0007385699427686632,
0.00005090383638162166
] |
en
| 0.999997 |
Furthermore, Yu et al. found that soil pH increased with the application of 4% Mn oxide-MB. Similar results were observed with soil amendments using coconut shell and carrot pulp biochars modified by 8% thiourea . Other studies also showed increased soil pH with the application of 3% iron-zinc oxide composite-modified corn straw biochar , 2% Fe-modified biochar , 0.6% Brassica napus biochar-UV , and 0.6% Lolium perenne biochar-UV . ii. Soil moisture
|
PMC11698939_p32
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 2.135943 |
other
|
Study
|
[
0.18794666230678558,
0.0008348948904313147,
0.8112184405326843
] |
[
0.9105212092399597,
0.07578815519809723,
0.012996257282793522,
0.0006944644846953452
] |
en
| 0.999996 |
Biochar application with a high surface area increases pore space and enhances soil moisture, which helps boost water retention capacity. Applying P-laden biochar considerably increased soil moisture by 93% over ordinary biochar when applied to acidic sandy soil planted with lettuce and improved seed germination and higher yield . Besides, soil moisture is enhanced by the EB derived from wood, switchgrass, and swine manure . It is claimed that nano-biochar contains larger pores and increases the number of small pores. Thus, it could increase the soil moisture content more than pristine biochar . Nano-biochar application enhanced soil water infiltration and soil moisture content . Similarly, nano-biochar was found to decrease soil water loss due to high surface area . Another, AB from the microwave catalytic process also increases water holding capacity by 98% more than ordinary biochar due to higher porosity, which shows a high correlation between WHC and micropore area .
|
PMC11698939_p33
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 4.018987 |
biomedical
|
Study
|
[
0.6633065938949585,
0.000892961397767067,
0.3358004093170166
] |
[
0.9938809871673584,
0.002777193672955036,
0.003254308132454753,
0.00008755557064432651
] |
en
| 0.999999 |
In another study on composite-MB, particle-sized biochar, and acidified biochar, it was found that all these modifications enhanced the soil water-stable aggregate contents. Specifically, acid-modified biochar at the 0–15 cm soil layer increased soil–water aggregate content by 1.45–1.80 times compared to pristine biochar, while also enhancing soil moisture content and infiltration rate .
|
PMC11698939_p34
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 2.574536 |
other
|
Study
|
[
0.1751016527414322,
0.001021014992147684,
0.8238772749900818
] |
[
0.9946646690368652,
0.004162061493843794,
0.001004741876386106,
0.00016848692030180246
] |
en
| 0.999997 |
Similarly, An et al. studied biochar made from peach shells and pig manure, modified with H 3 PO 4 and KOH, and applied in four dosages (0%, 2%, 3%, and 8%). They found that H 3 PO 4 -modified biochar had superior water retention compared to KOH-modified and pristine biochar, while KOH modification reduced the hydraulic functional groups on the biochar surface. Pig manure biochar demonstrated higher crack suppression intensity than that of other functionally activated biochars. However, the study generally recommended a 5–8% dosage for enhancing water retention and minimizing cracks . iii. Dosage of application
|
PMC11698939_p35
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 3.787653 |
biomedical
|
Study
|
[
0.7477812767028809,
0.0006588370888493955,
0.25155991315841675
] |
[
0.9965009689331055,
0.0017718637827783823,
0.001657266984693706,
0.0000698325238772668
] |
en
| 0.999997 |
The majority of biochar studies focused on application rates between 5 and 50 tons ha −1 , resulting in increased crop yield and soil properties and remediating pollutants in soil . However, this is not applicable in some cropping systems due to the high cost of production and transportation . However, several studies reported that biochar modification and application to the soil at certain rates effectively improve soil characteristics . Magnesium-oxide-derived biochar applied to saline rice paddy soils at 4.5 Mg ha −1 increases rice yields and adsorbs more phosphates . Similarly, applying Mn-oxide-MB at an increasing rate (0.5%, 1%, and 2% wt/wt) surged rice biomass and decreased As concentration in the root and rice grains compared to conventional biochar . In a similar investigation, the application of 1% magnesium-impregnated biochar to soil (wt/wt) increased available P content in the surface soil by around 50% . On the other hand, Fe-MB applied to saline paddy soil at 4.5 Mg ha −1 increased P adsorption via co-precipitation of P to iron oxides, thus increasing P availability by 79–90% over control . The yield of Cd and As-contaminated rice enhanced by Goethite-MB at the rate of (0.5%, 1.0%, and 1.5% wt/wt), the shoot biomass and root biomass increased around 56–88% and 55–98%, respectively. Also, goethite-MB decreases Cd and As concentration in rice tissues, improves photosynthesis capacity, and reduces oxidative stress . Likewise, acidified biochar derived from various raw materials, including rice husk, sugarcane-bagasse, and wheat straw, applied in the soil at 1.5% wt/wt, increased plant nutrient uptake and biomass by around 40 and 30%, respectively . Nano-biochar applied to salt-affected soils at different rates (0, 0.10, 0.20, and 0.50% wt/wt) increased P adsorption capacity . In another study, it was observed that nano-Fe-MB applied to soil at 0%, 0.05%, 0.1%, 0.2%, 0.4%, 0.8%, and 1.6% wt/wt concentrations reduced soil pH, Cd concentration and enhanced soil CEC. The application of lower rates (0.2–0.4%) of nano-Fe-MB effectively decreased Cd toxicity in the soil and rice. However, high nano-iron-MB application rates (0.8–1.6%) stimulated Cd toxicity in leaves. Thus, finding the optimum application rates should be taken into consideration to avoid risk and toxicity . Nano-hydroxyapatite applied at different levels (1%, 5%, 10%, and 20%) in Pb-contaminated soils effectively immobilized Pb by around 44–57% after 28 days of incubation, effectively decreasing Pb toxicity in soils and accumulation in plants . iv. The ratio of functional material saturation
|
PMC11698939_p36
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 4.148952 |
biomedical
|
Study
|
[
0.938502848148346,
0.0011346342507749796,
0.06036248058080673
] |
[
0.9359944462776184,
0.0008830858860164881,
0.0629730299115181,
0.00014950985496398062
] |
en
| 0.999998 |
The ratio of functional material to modify biochar was one of the primary gauges for the adsorption of pollutants . Biochar activation was done by soaking raw biochar in solution (30% H 2 O 2 , 1 M HCl, and 1 M KOH) (1:100 ratio) for 24 h to effectively adsorb Cr (VI). The ratio of Fe to nano-Fe-modified-biochar was 19.5%, effectively improving soil properties (CEC) and reducing Cd toxicity . Similarly, Fe and Al-MB, at the ratio of 1 mol L −1 in FeCl 3 and AlCl 3 , effectively increased soil pH from 6.93 to 7.30 and enhanced P retention capacity . Furthermore, magnetic biochar prepared by mixing biomass with a solution containing (a 1:1 molar ratio of FeCl 2 and FeCl 3 ) effectively remediates soil and adsorbed heavy metals, including As, Cd, and Pb . In a recent study, Mg–Al impregnated biochar at 1:20 g ml −1 (solid to liquid ratio) was observed to be adequate in adsorbing phosphate in the soil and contained a higher amount of oxygen functional groups (MgO and AlO) as compared to pristine biochar . Similarly, MB nanoparticles exhibited a maximum adsorption capacity of 147 mg g −1 , significantly higher than the 67.8 mg g −1 capacity of unmodified biochar . This enhancement is attributed to the nanoparticles increasing the surface area and the number of functional groups on the MB surface. Moreover, KOH modification of biochar resulted in a substantial increase (approximately 2.4 times) in specific surface area and more than a 50% improvement in the adsorption capacity for Cd 2+ and Cu 2+ ions. Specifically, pristine biochar had a specific surface area of 189 m 2 g −1 , whereas KOH-MB had a surface area of 455 m 2 g −1 . The Cd 2+ adsorption capacity of pristine biochar was recorded as 4.48 mg g −1 , while KOH-treated biochar achieved a capacity of 6.81 mg g −1 , representing a 50.7% significant increase. However, the Cu 2+ adsorption capacity of unmodified biochar was 2.64 mg g −1 , whereas the KOH-modified biochar showed a significantly enhanced capacity of 4.03 mg g −1 . v. Soil types
|
PMC11698939_p37
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 4.244823 |
biomedical
|
Study
|
[
0.9967792630195618,
0.0004053942102473229,
0.002815306419506669
] |
[
0.9984028935432434,
0.0002115030074492097,
0.0013274213997647166,
0.00005819557190989144
] |
en
| 0.999997 |
The physicochemical properties of soil, including texture, structure, pH, and organic matter content, can influence the interactions between MB and soil, consequently affecting the availability and mobility of nutrients and contaminants. . It is worth noting that sandy soils with low CEC and organic matter content may have limited capacity for MB adsorption and nutrient retention. This, in turn, leads to an increased adsorption of MB and an improvement in nutrient retention . MB also increases the presence of organic matter. For instance, Kun et al. found a significant increase in soil C/N ratios and soil organic carbon after the application of Cd-binding biochar. Furthermore, observed a higher accumulation of soil organic matter (SOM) and organic carbon with the application of rice husk biochar modified with NaOH, HNO 3 , and dimethyl dithiocarbamate sodium (3% w/w).
|
PMC11698939_p38
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 4.101062 |
biomedical
|
Study
|
[
0.958093523979187,
0.0004822945047635585,
0.04142412170767784
] |
[
0.9975571632385254,
0.0008194553083740175,
0.0015725343255326152,
0.000050749655201798305
] |
en
| 0.999995 |
Similarly, Moradi and Karimi noted increased SOM and organic carbon with Fe-modified biochar (2% w/w). Higher organic matter was also observed with the application of 2% (w/w) Fe–Mn biochar , 1% (w/w) S-biochar , 1% (w/w) S-Fe biochar, 3% (w/w) , iron-modified biochar, 8% (w/w) thiourea-modified biochar , 8% (w/w) carrot pulp biochar, and 3% (w/w) iron-zinc oxide composite modified corn straw biochar, compared to pristine biochar . This variation can be attributed to the slower decomposition of biochar depending on the soil type. The formation of soil aggregates or organo-mineral complexes provides substantial physical protection to SOM, potentially preventing its decomposition. Additionally, the temperature sensitivity varying with soil type limits short-term decomposer access to SOM, while the majority of decomposition is carried out by slower microbial metabolism . For instance, in a study by Feng , it was observed that the temperature sensitivities of biochar vary in soils with different textures and mineralogy. The temperature coefficient ( Q 10) values of biochars ranged from 1.93 to 2.20 in Oxisols and from 2.74 to 2.77 in Vertisols, within a temperature range of 20–40 °C. Additionally, the presence of biochar was found to alter the Q 10 values of native SOM as well, depending on the soil type .
|
PMC11698939_p39
|
PMC11698939
|
Effects of modified biochar on soil attributes
| 4.119504 |
biomedical
|
Study
|
[
0.9851478934288025,
0.0005396972992457449,
0.014312323182821274
] |
[
0.99562007188797,
0.0002798107161652297,
0.004041756968945265,
0.000058360597904538736
] |
en
| 0.999997 |
Following the advancements and findings outlined in earlier sections, future research on MB should prioritize several key areas to address existing gaps and enhance our understanding. These research efforts can be categorized into four main segments. However, to achieve optimum results, collaborative efforts among experts from different domains are strongly recommended. Analytical advancement Developing Advanced Techniques : Employ more sophisticated techniques such as Pyrolysis Gas Chromatography-Mass Spectrometry (Py-GC–MS) and Thermogravimetric-Fourier Transform Infrared Spectroscopy-Mass Spectrometry (TG-FTIR-MS) to elucidate biochar formation mechanisms more accurately. Advanced Spectroscopy : Apply advanced spectroscopic methods to gain deeper insights into the functionalization of MB, allowing for better control over functional groups and porosity. Integrated Approaches : Use a combination of unique spectroscopic investigations and theoretical modeling to enhance the understanding of factors impacting biochar efficiency after soil amendment. Future perspectives in fundamental and material research Mechanism Investigation : Explore the mechanisms behind changes in biochar properties due to different pyrolysis conditions or modification procedures. Prioritize sustainable feedstock materials and their functionalization for specific contaminants to promote a green and sustainable environment. Synergistic Integration : Investigate the potential for synergistic integration with other treatment modalities, such as combining MB with biofilters, to enhance biochar's adsorption capabilities and address environmental challenges.
|
PMC11698939_p40
|
PMC11698939
|
Future prospective
| 4.04095 |
biomedical
|
Review
|
[
0.9853833913803101,
0.0006334231002256274,
0.013983294367790222
] |
[
0.3938446640968323,
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en
| 0.999996 |
Regeneration Processes : As biochar research advances, it brings forth new challenges and dilemmas. A primary concern revolves around regeneration processes. Addressing how to efficiently desorb pollutants adsorbed on biochar for subsequent safe treatment and optimizing the recycling of the adsorbed biochar stands as paramount issues requiring meticulous consideration. Environmental Risks : A critical aspect under scrutiny is the risk of secondary pollution arising from MB. For instance, there is a pertinent question regarding the possible interaction of metal-MB with other environmental compounds following its application in soil and leaking into groundwater. Understanding the possibility of antagonistic effects with different compounds and developing effective methods for separating treated biochar from soil and groundwater are pressing issues that demand immediate attention in future research endeavors. Future research in aging and stability Long-Term Effects : Investigating the long-term effects of MB on soil functions and its behavior across diverse soil types necessitates immediate attention. A recent study illustrated the direct influence of MB on soil biological communities' composition and abundance, as well as affects the retention of applied pesticides . Consequently, weed control in MB-amended soils may pose challenges, as the efficacy of preemergence herbicides could diminish. Environmental Behavior: MB proved to facilitate the formation of soil aggregates, enhance the physical protection of organic carbon, and increase yield production, with other positive environmental impacts such as the decrease in methane and gross greenhouse gas emissions. However, these initial positive effects might shift to negative over time, necessitating attention to the long-term environmental behavior of MB. It is particularly crucial to investigate how biochar interacts with minerals and how such interactions affect the performance of soil and water remediation over short-term and long-term aging. Addressing these issues in future research is imperative for a comprehensive understanding of MB's role and impact on soil. Simulated Aging Methods : There is a need to develop simulated aging methods that integrate multiple artificial aging processes. Specifically, considering the aging time scale in natural environments, it is crucial to quantitatively explore response models of MB properties using various artificial aging methods. This approach will enhance our understanding of how biochar evolves over time under environmental conditions and improve the accuracy of predictions regarding its behavior and efficacy in practical soil applications and its implications for different crop systems. Geochemical Behavior : In the context of pollutant management by MB, there exists a pressing need for further exploration into the geochemical behavior of emerging contaminants under long-term application MB. Understanding how MB aging interacts with and influences the fate of emerging contaminants across diverse environmental contexts is crucial for devising effective pollutant remediation and management strategies. For instance, investigating potential scenarios such as the movement of MB to groundwater and the release of metals in the case of metal modification. However, the impacts of such interactions are contingent upon soil types, with sandy soils often exhibiting more significant benefits compared to others . As a result, there is an urgent need for extensive research on the long-term effects of MB across various soil types.
|
PMC11698939_p41
|
PMC11698939
|
Emerging environmental research concerns
| 4.255114 |
biomedical
|
Study
|
[
0.9716078042984009,
0.0009306197753176093,
0.027461593970656395
] |
[
0.7770622372627258,
0.003097542328760028,
0.21957620978355408,
0.00026402363437227905
] |
en
| 0.999996 |
In summary, focusing on these future research areas will advance our understanding of MB and its applications. An integrated and collaborative approach will be essential for achieving comprehensive and impactful results.
|
PMC11698939_p42
|
PMC11698939
|
Emerging environmental research concerns
| 2.323506 |
biomedical
|
Other
|
[
0.9877013564109802,
0.0013574569020420313,
0.010941154323518276
] |
[
0.01256529986858368,
0.9544405937194824,
0.032092586159706116,
0.0009015023242682219
] |
en
| 0.999995 |
In conclusion, this article explores the physicochemical characteristics of biochar altered through various techniques, emphasizing the significance of comprehending the impact of these alterations on biochar properties. This insight will assist readers in discerning effective methods to modify biochar for specific applications. Our assessment suggests that MBs have significant potential for improving soil quality and health, and mitigating greenhouse gases. Furthermore, environmentally-friendly modifications can enhance energy and carbon storage in soils. Additionally, this review will offer comprehensive insights into advanced analytical techniques developed to analyze modifications necessary prior to application, enabling precise targeting of specific objectives. However, further investigation is required to analyze the relationships between material composition, structure, and energy storage. Overall, this article contributes to our understanding of the potential of MB as a versatile and sustainable material with significant environmental and economic benefits.
|
PMC11698939_p43
|
PMC11698939
|
Conclusion
| 3.632263 |
other
|
Review
|
[
0.4665793180465698,
0.006758504081517458,
0.5266621708869934
] |
[
0.015322241932153702,
0.004288855940103531,
0.9799779057502747,
0.00041107358993031085
] |
en
| 0.999998 |
This comprehensive review thoroughly explores the recent advances in utilizing Modified biochar (MB), specifically in soils. Beyond mere synthesis, it delves into the evolved physicochemical characteristics of MB, providing invaluable insights into its efficacy and limitations. Indeed, comprehending the unique properties endowed by each modifying agent is paramount, as they directly shape the characteristics of the final product. Therefore, it is imperative to fully grasp the attributes of both MB and the modifying agent prior to production, enabling targeted applications within soil environments.
|
PMC11698939_p44
|
PMC11698939
|
Outlook
| 3.702573 |
biomedical
|
Review
|
[
0.7334702610969543,
0.008964119479060173,
0.25756555795669556
] |
[
0.003846297739073634,
0.002814380917698145,
0.9929927587509155,
0.0003465005720499903
] |
en
| 0.999998 |
However, in the rapidly advancing world, it is essential to ascertain the exact nature and properties of processed MB. Hence, our review underscores the significance of embracing advanced analytical methodologies to characterize modified biochar and gauge its effectiveness precisely. By doing so, we aim to shed light on the crucial role these techniques play in ensuring biochar quality and performance in modern applications. Furthermore, this paper contains a comprehensive discussion of the mechanisms behind the factors influencing the efficiency of MB post-soil application.
|
PMC11698939_p45
|
PMC11698939
|
Outlook
| 3.629222 |
biomedical
|
Review
|
[
0.7149872779846191,
0.007257834076881409,
0.27775490283966064
] |
[
0.007571634836494923,
0.0027485231403261423,
0.9893669486045837,
0.00031290354672819376
] |
en
| 0.999999 |
Additionally, we have highlighted the need for future research to explore the mechanisms behind alterations in biochar properties due to different modifications. Our future research perspective section is delineated into four segments. Firstly, analytical advancement advocates for leveraging sophisticated techniques, such as Pyrolysis Gas Chromatography-Mass Spectrometry (Py-GC–MS) and Thermogravimetric-Fourier Transform Infrared Spectroscopy-Mass Spectrometry (TG-FTIR-MS) to deepen our comprehension of biochar formation mechanisms. Additionally, it underscores the significance of advanced spectroscopic methods in elucidating modified biochar functionalization for precise control over functional groups and porosity. Secondly, future research in fundamental and material research underscores the importance of synergistically integrating MB with other treatment modalities, and investigating the mechanisms underlying changes in biochar properties resulting from modification procedures.
|
PMC11698939_p46
|
PMC11698939
|
Outlook
| 4.010375 |
biomedical
|
Study
|
[
0.9749670624732971,
0.00034130801213905215,
0.024691568687558174
] |
[
0.9026456475257874,
0.022343067452311516,
0.07481838762760162,
0.0001928742422023788
] |
en
| 0.999997 |
Moreover, concerns regarding risks associated with MB are pointed out in the environmental research section, such as the risk of secondary pollution by potential leakage into groundwater after application, the possibility of antagonistic effects, and the development of new regeneration processes to enhance pollutant absorption efficiency. Lastly, the roadmap for aging and stability future research delves into the necessity of focusing on the long-term effects of MB on soil functions and its behavior across diverse soil types. This entails comprehensively understanding MB role and impact on soil by developing simulated aging methods that integrate multiple artificial aging processes. This will enhance the accuracy of predictions concerning MB's behavior and efficacy in practical soil applications and its implications for different crop systems.
|
PMC11698939_p47
|
PMC11698939
|
Outlook
| 2.889916 |
other
|
Study
|
[
0.24272622168064117,
0.0009583822684362531,
0.7563154101371765
] |
[
0.5988044142723083,
0.38295218348503113,
0.017385052517056465,
0.0008583847084082663
] |
en
| 0.999995 |
Although advances in diagnostics and treatments have improved the outcome of patients with primary breast cancer, approximately one in three will still develop metastatic disease . Metastatic breast cancer (MBC) is generally considered incurable with an estimated median overall survival (OS) of approximately two to three years, and a five-year survival rate of merely 25% .
|
39751847_p0
|
39751847
|
Introduction
| 3.878141 |
biomedical
|
Review
|
[
0.9977602958679199,
0.0016949562123045325,
0.0005447682342492044
] |
[
0.10662619769573212,
0.059196751564741135,
0.8327203989028931,
0.0014566899044439197
] |
en
| 0.999997 |
Predicting prognosis and treatment response in MBC is clinically challenging, highlighting a need for novel biomarkers to improve tailoring of individualized therapies . The immunological composition of the primary tumor microenvironment has gained attention, with distinct cellular populations conferring prognostic information in primary breast cancer . However, the dynamics of the immune landscape during tumor progression and its clinical relevance in metastatic tissue remains unclear. Investigation of the immune landscape in both lymph node and distant metastases is crucial for understanding tumor progression in MBC. In addition, with the rapid development of immune therapies, insights into the complex interactions between cancer cells and immune responses in MBC is urgently needed.
|
39751847_p1
|
39751847
|
Introduction
| 4.093246 |
biomedical
|
Review
|
[
0.998591959476471,
0.0009255731711164117,
0.00048249828978441656
] |
[
0.2768261730670929,
0.002521671587601304,
0.7199410200119019,
0.0007111277082003653
] |
en
| 0.999996 |
CD163 is a scavenger receptor expressed on anti-inflammatory cells of the myeloid lineage. While being a common marker for tumor associated macrophages (TAMs), CD163 may also be expressed on monocytic myeloid-derived suppressor cells (Mo-MDSCs) . Numerous studies have indicated that presence of CD163 + immune cells is associated with clinicopathological features and prognosis in a wide range of malignancies, including breast cancer . In patients with primary breast cancer, significant associations have been made for high densities of CD163 + immune cells and higher tumor grade, larger tumor size, lymph node positivity, Ki67-positivity, hormone receptor negativity and/or triple negative/basal like subtypes [ 7 – 12 ].
|
39751847_p2
|
39751847
|
Introduction
| 4.111335 |
biomedical
|
Study
|
[
0.9995232820510864,
0.0002169378421967849,
0.0002597802958916873
] |
[
0.9850689768791199,
0.00036697188625112176,
0.014447229914367199,
0.00011679968156386167
] |
en
| 0.999998 |
In accordance with the associations to adverse clinicopathological features, high densities of CD163 + immune cells associate with poor OS, breast cancer specific survival (BCSS), and/or recurrence-free survival (RFS) in patients with primary breast cancer [ 7 – 11 , 13 ]. However, there have been contradictory reports including studies indicating no associations between high infiltration of CD163 + immune cells and overall and disease-free survival, as well as other studies showing association with improved OS in patients with estrogen receptor (ER)-negative or triple negative (TNBC) tumors . Furthermore, the localization of CD163 + immune cells has been shown to be of prognostic importance. Some studies indicate that high densities of CD163 + cells in the tumor stroma but not in the tumor nest is associated with poor OS, PFS and/or BCSS , while other studies indicate that high CD163 + density in the tumor nest associate with unfavorable OS . The presence of CD163 + immune cells in different regions may consequently confer different prognostic values, however, there is a lack of studies in metastatic tissue.
|
39751847_p3
|
39751847
|
Introduction
| 4.16562 |
biomedical
|
Study
|
[
0.998691737651825,
0.0006124306237325072,
0.0006958247977308929
] |
[
0.804499626159668,
0.0006874182727187872,
0.1944475620985031,
0.00036544454633258283
] |
en
| 0.999996 |
Although current literature supports the prognostic potential of CD163 + immune cells and associations to adverse clinicopathological features in primary breast cancer, the role of CD163 + immune cells in MBC is still unclear. How CD163 expression changes during tumor progression, the prognostic value and potential relevance of the tumoral localization of CD163 + immune cells in metastatic tissue remain uncharacterized. In this exploratory study we evaluate CD163 + immune cell levels in primary tumors (PT) and corresponding lymph node metastases (LNM) and distant metastases (DM) by immunohistochemistry (IHC) and gene expression (GEX) analyses in a cohort of 139 patients with newly diagnosed MBC. We aim to determine changes and distribution of CD163 + immune cell levels in specific tumor regions (tumor nest and tumor stroma) of PT, LNM and DM, and evaluate potential associations of CD163 levels at these distinct sites with clinicopathological characteristics and survival (PFS and OS).
|
39751847_p4
|
39751847
|
Introduction
| 4.149441 |
biomedical
|
Study
|
[
0.9993332028388977,
0.0004999535158276558,
0.00016677573148626834
] |
[
0.9990540146827698,
0.0002536626998335123,
0.0005859272205270827,
0.00010640919936122373
] |
en
| 0.999998 |
156 patients with newly diagnosed MBC were included in the prospective observational CTC-MBC trial conducted in southern Sweden, during 2011–2016, previously described in detail . In short, inclusion criteria were newly diagnosed MBC, age > 18 years, performance status according to Eastern Cooperative Oncology Group (ECOG) 0–2, and a predicted life expectancy of > 2 months. Ethical approval was obtained from the Regional Ethics Committee at Lund University , and all patients signed a written informed consent. Systemic therapy was decided by the treating physician in accordance with clinical guidelines and patients evaluated approximately every three months, according to clinical routine, for progression versus non-progression using modified Response Evaluation Criteria In Solid Tumors (RECIST) . All clinicopathological data were prospectively collected in case report forms and reported in detail in Larsson et al. . The study was performed in accordance with the REMARK criteria .
|
39751847_p5
|
39751847
|
Patient cohort
| 4.058145 |
biomedical
|
Study
|
[
0.8833689093589783,
0.11503656208515167,
0.0015944979386404157
] |
[
0.8247323036193848,
0.16640473902225494,
0.0021259617060422897,
0.006736984942108393
] |
en
| 0.999996 |
Formalin-fixed, paraffin-embedded tissue from primary tumors (PT), lymph node metastases (LNM) and distant metastases (DM) was retrospectively obtained and core biopsies from areas with invasive cancer were constructed into a TMA. Antigen retrieval was performed in a pressure cooker using citrate buffer (pH 6, DAKO) and staining was performed using a validated CD163 antibody (Novocastra, clone 10D, 1:100). The antibody was validated in tonsil using macrophages as positive control and lymphocytes and epithelial cells as negative controls. Tissue samples from 139 patients out of 156 patients recruited were scored for CD163 expression due to inadequate amount of tissue for staining or sections containing no tumor cells or mostly necrotic cells . Density levels of infiltrating CD163 + immune cells in the tumor nest and tumor stroma were semi-quantitatively scored according to four categories (none , low , medium , or high density levels) by two individual observers (KL, FBG) in a blinded manner. Discordant cases were reevaluated and discussed until consensus was reached. Representative IHC stainings of the different density level categories (0–3) are shown in Fig. 1 C. Fig. 1 Flowchart of study cohort and representative IHC staining. A. Flow chart of patient inclusion for the present study. B. Venn diagram of the distribution of patient-matched samples. C. Representative IHC staining of CD163 from primary tumors. Left, “low CD163”; none (0) CD163 in the tumor nest and low levels (1) in the tumor stroma. Right, “high CD163”; medium levels (2) of CD163 in the tumor nest and high levels (3) in the tumor stroma. For the majority of analyses, the CD163 levels were dichotomized into low (0/none + low expression (1); left panel ) and high (medium (2) + high expression (3); right panel ) in the tumor nest and tumor stroma
|
39751847_p6
|
39751847
|
Tissue microarray (TMA) and immunohistochemistry (IHC)
| 4.143528 |
biomedical
|
Study
|
[
0.9992777705192566,
0.0005271596601232886,
0.00019512229482643306
] |
[
0.99937504529953,
0.00024234640295617282,
0.00029603950679302216,
0.0000866073023644276
] |
en
| 0.999996 |
Tumor tissue from PT, LNM and DM were processed; RNA was isolated and analyzed using the NanoString Breast Cancer 360™ assay on a NanoString nCounter® SPRINT Profiler (NanoString Technologies Inc), as previously described . GEX data generated from the original cohort was primarily used for PAM50 classification and for evaluation of changes in GEX patterns during tumor progression . For the current study, CD163 expression was normalized using the mean and standard deviation of all the samples irrespective of tumor site to enable comparisons across sites. Correlations between CD163 expression and survival in an independent dataset , comprising 3207 patients with primary breast cancer , was performed using the publicly available database R2: microarray analysis and visualization platform ( http://r2.amc.nl ).
|
39751847_p7
|
39751847
|
Gene expression (GEX) analysis of CD163
| 4.072717 |
biomedical
|
Study
|
[
0.9995003938674927,
0.00026420538779348135,
0.00023547706950921565
] |
[
0.9995309114456177,
0.00018600342446006835,
0.00023043413239065558,
0.000052655301260529086
] |
en
| 0.999997 |
Statistical analyses were performed using IBM SPSS Statistics 28 or 29 (correlations to clinicopathological parameters and outcome), and R version 4.3.2 using RStudio (Sankey diagrams and GEX analyses). Sankey plots were constructed using the R package ggsankey . Associations between dichotomized CD163 + immune cell density levels (“low”: none and low , “high”: medium and high levels) and clinicopathological variables were analyzed using Pearson’s chi-squared test or Fisher’s exact test. The relationship between CD163 GEX and IHC was tested using linear regression models. Comparisons of PFS and OS were analyzed using Log-rank test and visualized using Kaplan–Meier curves. Univariate and multivariate Cox regression analyses were used to adjust for established prognostic factors (age at MBC diagnosis, ECOG performance status, histological grade (NHG), subtype, metastasis-free interval (MFI), number of metastatic sites, site of metastasis (non-visceral or visceral) and circulating tumor cells (CTCs) at baseline), as depicted previously . P -values < 0.05 were considered statistically significant. Time to progression (PFS) or death of any cause (OS) was calculated from baseline (at study inclusion) and patients without events were censored at last follow-up. Comparison of survival times from primary breast cancer diagnosis to death were calculated from date of initial breast cancer diagnosis and patients without events were censored at last follow-up. Due to the exploratory nature of this study, no analyses to adjust for multiple testing were performed.
|
39751847_p8
|
39751847
|
Statistical analyses
| 4.069733 |
biomedical
|
Study
|
[
0.999321699142456,
0.00047665691818110645,
0.00020171437063254416
] |
[
0.9992276430130005,
0.00028354799724183977,
0.0004055908939335495,
0.00008316944149555638
] |
en
| 0.999998 |
Of the 156 patients in the original cohort , tissue samples from 139 patients with newly diagnosed MBC were scored for density levels of CD163 + immune cells . Patient and tumor characteristics of the CD163 cohort, compared to the original cohort, are summarized in Table 1 . The median age at MBC diagnosis was 65 years (range 40–90 years). 94 patients (70.1%) had ER-positive (HER2-negative) disease, 16 (11.9%) had HER2-positive disease and 24 (17.9%) had TNBC as determined by ER and HER2 staining in metastases first-hand and primary tumors (PT) secondly. With regards to PAM50 subtype of the PT, 47 patients (38.5%) had Luminal A, 45 patients (36.9%) Luminal B, 14 patients (11.5%) had HER2-positive, and 16 patients (13.1%) had basal-like primary tumors. 85 patients (61.2%) had an MFI of > 3 years, 26 patients (18.7%) ≤ 3 years, and 28 patients (20.1%) had de novo MBC ( i.e., distant metastasis at initial diagnosis). 93 patients (66.9%) had < 3 metastatic sites, 46 patients (33.1%) had ≥ 3 metastatic sites and 82 patients (59.0%) had visceral metastases (metastases in ascites, pleura, liver, lungs or the central nervous system). The median follow-up time was 90 months (range 74–131 months). Table 1 Patient and tumor characteristics of the CD163 cohort compared to the original cohort Variable CD163 cohort Whole original cohort Total n = 139 Total n = 156 Age at MBC diagnosis (years) < 65 69 (49.6%) 75 (48.1%) ≥ 65 70 (50.4%) 81 (51.9%) ECOG at MBC diagnosis 0 80 (58.8%) 91 (60.7%) 1 35 (25.7%) 37 (24.7%) 2 21 (15.4%) 22 (14.7%) Unknown 3 6 PT NHG I 11 (10.0%) 13 (10.5%) II 57 (51.8%) 65 (52.4%) III 42 (38.2%) 46 (37.1%) Unknown 29 32 PT tumor size T1 46 (35.1%) 57 (38.8%) T2 47 (35.9%) 51 (34.7%) T3 20 (15.3%) 20 (13.6%) T4 18 (13.7%) 19 (12.9%) Unknown 8 9 PT node status Negative 35 (28.9%) 44 (32.4%) Positive 86 (71.1%) 92 (67.6%) Unknown 18 20 PT subtype (PAM50) Luminal A 47 (38.5%) 47 (38.2%) Luminal B 45 (36.9%) 45 (36.9%) HER2-pos 14 (11.5%) 15 (12.3%) Basal 16 (13.1%) 16 (13.1%) Unknown 17 33 Subtype (IHC) metastases first Estrogen receptor-positive (ER + , HER2 − ) 94 (70.1%) 105 (69.5%) HER2-positive 16 (11.9%) 20 (13.2%) TNBC 24 (17.9%) 26 (17.2%) Unknown 5 5 Metastasis free interval (MFI) 0 years (de novo MBC) 28 (20.1%) 31 (19.9%) > 0 but ≤ 3 years 26 (18.7%) 28 (17.9%) > 3 years 85 (61.2%) 97 (62.2%) Metastatic sites, n < 3 93 (66.9%) 109 (69.9%) ≥ 3 46 (33.1%) 47 (30.1%) Visceral metastases No 57 (41.0%) 65 (41.7%) Yes 82 (59.0%) 91 (58.3%) CTC at BL < 5 64 (46.0%) 73 (48.0%) ≥ 5 74 (54.0%) 79 (52.0%) Unknown 1 4
|
39751847_p9
|
39751847
|
Patient and tumor characteristics
| 4.194098 |
biomedical
|
Study
|
[
0.9983288645744324,
0.0014026546850800514,
0.0002684786741156131
] |
[
0.99910968542099,
0.00046953005949035287,
0.0002666796208359301,
0.00015409184561576694
] |
en
| 0.999998 |
The levels of CD163 + immune cells were determined in 117 PT, 70 lymph node metastases (LNM) and 59 distant metastases . Representative IHC stainings are presented in Fig. 1 C. Overall, the density levels of CD163 + immune cells were higher in the tumor stroma compared to the tumor nest, but the patterns were similar across the tumor locations . Next, we visualized changes in CD163 + immune cells in the tumor nest and tumor stroma during tumor progression using Sankey diagrams of patient-matched tissue samples. Approximately half of the patients displayed changes in the density levels of CD163 + immune cells between the sites , however, these changes were not significant as determined by McNemar analysis (data not shown). To summarize, distribution of CD163 + immune cells is similar across tumor sites (PT, LNM and DM) and observed changes during tumor progression were not significant. Fig. 2 Changes in the levels of CD163 + immune cells from primary tumors to lymph node metastases and distant metastases. A Pie charts depicting the distribution of CD163 levels and frequency (%) in the tumor nest ( left panels ) and tumor stroma ( right panels ) of primary tumors (PT; upper panels ), lymph node metastases (LNM; middle panels ) and distant metastases (DM; lower panels ). B – D . Sankey diagram depicting changes in the levels of CD163 + cells in the tumor nest ( upper panel ) and tumor stroma ( lower panel ) over time from PT to LNM (B; n = 57), PT to DM (C; n = 48) and LNM to DM (D; n = 27). E . Summary of number of patients ( n ) and percentage (%) that display changes in the levels of CD163 + immune cells between tumor tissues in the tumor nest ( upper panel ) and tumor stroma ( lower panel )
|
39751847_p10
|
39751847
|
Distribution and changes in CD163 + immune cells during tumor progression
| 4.120451 |
biomedical
|
Study
|
[
0.9993603825569153,
0.00039827791624702513,
0.0002413269248791039
] |
[
0.999452531337738,
0.00015991686086636037,
0.00032064630067907274,
0.00006688041321467608
] |
en
| 0.999997 |
Next, we dichotomized the levels of CD163 + immune cells into “low” (none + low density level) and “high” and analyzed possible associations to clinicopathological variables (Table 2 ). High levels of CD163 + immune cells in the PT nest associated significantly with higher NHG ( P = 0.023), intrinsic PAM50 basal-like subtype ( P = 0.007) and a shorter MFI ( P = 0.040; Table 2 , left panel). Similarly, high levels of CD163 + immune cells in the PT stroma associated with higher tumor grade ( P = 0.030) and molecular subtype Luminal B and basal-like. In contrast, low levels of CD163 + immune cells associated with Luminal A subtype ( P = 0.003) (Table 2 , right panel). With regards to the levels of CD163 + immune cells in the tumor nest and stroma of LNM and DM, only a few significant associations were observed (data not shown); low levels of CD163 + immune cells in the LNM stroma associated with presence of visceral metastases ( P = 0.009) whereas high levels of CD163 + immune cells in the DM tumor stroma associated with more metastatic sites (≥ 3 metastatic sites P = 0.048). Table 2 Correlations between CD163 + immune cells in the primary tumor nest ( left ) and stroma ( right ) and clinical parameters Variable Total n = 117 Primary tumor (PT) nest Primary tumor (PT) stroma Low CD163 n = 95 High CD163 n = 22 P -value Low CD163 n = 25 High CD163 n = 92 P -value Age (years) < 65 57 45 (47.4%) 12 (54.5%) 0.544 a 12 (48%) 45 (48.9%) 0.935 a ≥ 65 60 50 (52.6%) 10 (45.5%) 13 (52%) 47 (51.1%) Baseline ECOG 0 68 59 (62.8%) 9 (40.9%) 0.129 b 19 (76.0%) 49 (53.8%) 0.154 b 1 30 21 (22.3%) 9 (40.9%) 4 (16.0%) 26 (28.6%) 2 18 14 (14.9%) 4 (18.2%) 2 (8.0%) 16 (17.6%) Unknown 1 1 0 0 1 PT NHG I 8 8 (10.8%) 0 (0.0%) 0.023 b 2 (10.5%) 6 (8.1%) 0.030 b II 47 41 (55.4%) 6 (31.6%) 14 (73.7%) 33 (44.6%) III 38 25 (33.8%) 13 (68.4%) 3 (15.8%) 35 (47.3%) Unknown 24 21 3 6 12 PT tumor size T1 39 32 (35.6%) 7 (31.8%) 0.894 b 9 (37.5%) 30 (34.1%) 0.722 b T2 41 33 (36.7%) 8 (36.4%) 8 (33.3%) 33 (37.5%) T3 17 14 (15.6%) 3 (13.6%) 5 (20.8%) 12 (13.6%) T4 15 11 (12.2%) 4 (18.2%) 2 (8.3%) 13 (14.8%) Unknown 5 5 0 1 4 PT node status Negative 32 23 (28.0%) 9 (42.9%) 0.191 a 6 (27.3%) 26 (32.1%) 0.664 a Positive 71 59 (72.0%) 12 (57.1%) 16 (72.7%) 55 (67.9%) Unknown 14 13 1 3 11 PT subtype (PAM50) Luminal A 45 41 (43.6%) 4 (18.2%) 0.007 b 17 (70.8%) 28 (30.4%) 0.003 b Luminal B 43 35 (37.2%) 8 (36.4%) 3 (12.5%) 40 (43.5%) HER2-positive 12 10 (10.6%) 2 (9.1%) 2 (8.3%) 10 (10.9%) Basal 16 8 (8.5%) 8 (36.4%) 2 (8.3%) 14 (15.2%) Unknown 1 1 0 1 0 BC subtype (IHC) based on metastasis first ER-positive 81 66 (73.3%) 15 (68.2%) 0.052 b 20 (83.3%) 61 (69.3%) 0.388 b HER2-positive 11 11 (12.2%) 0 (0.0%) 2 (8.3%) 9 (10.2%) TNBC 20 13 (14.4%) 7 (31.8%) 2 (8.3%) 18 (20.5%) Unknown 0 0 0 1 4 Time from PT to metastasis (MFI) 0 (de novo MBC) 23 20 (21.1%) 3 (13.6%) 0.040 b 3 (12.0%) 20 (21.7%) 0.300 b > 0 but ≤ 3 23 14 (14.7%) 9 (40.9%) 3 (12.0%) 20 (21.7%) > 3 71 61 (64.2%) 10 (45.5%) 19 (76.0%) 52 (56.5%) Metastatic sites, n < 3 78 65 (68.4%) 13 (59.1%) 0.403 a 18 (72.0%) 60 (65.2%) 0.524 a ≥ 3 39 30 (31.6%) 9 (40.9%) 7 (28.0%) 32 (34.8%) Metastatic localization Visceral 49 40 (42.1%) 9 (40.9%) 0.918 a 12 (48.0%) 37 (40.2%) 0.484 a Non-visceral Visceral 68 55 (57.9%) 13 (59.1%) 13 (52.0%) 55 (59.8%) CTC at baseline < 5 55 47 (49.5%) 8 (36.4%) 0.267 a 9 (36.0%) 46 (50.0%) 0.214 a ≥ 5 62 48 (50.5%) 14 (63.6%) 16 (64.0%) 46 (50.0%) High and low levels of CD163 + immune cells in the primary tumor nest and stroma were associated with clinical parameters. Statistics by a. Pearson Chi-squared or b. Fisher’s exact test when expected counts were < 5 in ≥ 1 cell. P -values < 0.05 are highlighted in bold
|
39751847_p11
|
39751847
|
CD163 + immune cells in the primary tumor associate to clinical parameters and gene expression (GEX)
| 4.144215 |
biomedical
|
Study
|
[
0.9993813037872314,
0.0003559421165846288,
0.0002627189678605646
] |
[
0.9993777275085449,
0.00014841585652902722,
0.000408449734095484,
0.00006543105700984597
] |
en
| 0.999998 |
In conjunction with previous GEX analyses of the original cohort for PAM50 classification and evaluation of changes in GEX patterns during tumor progression , we also obtained information regarding CD163 GEX on the same matched material. This allowed us to analyze the concordance between CD163 levels as assessed by IHC and GEX. Overall, CD163 GEX levels from bulk tissue correlated well with the four scoring categories of CD163 by IHC (density level none , low , medium and high ) in tumor stroma at all sites . These results indicate that high density levels of CD163 + immune cells in the tumor nest and stroma of the PT, and less so in the DM, associate with adverse clinical features. Furthermore, there is a high degree of concordance between CD163 levels as assessed by IHC and GEX.
|
39751847_p12
|
39751847
|
CD163 + immune cells in the primary tumor associate to clinical parameters and gene expression (GEX)
| 4.099656 |
biomedical
|
Study
|
[
0.9994338154792786,
0.000300442217849195,
0.0002657076111063361
] |
[
0.9994980096817017,
0.00014656793791800737,
0.00029896580963395536,
0.00005642986070597544
] |
en
| 0.999999 |
To further determine potential prognostic relevance of CD163 + immune cells in PT, LNM and DM of patients with MBC, we next performed log-rank tests illustrated with Kaplan–Meier curves to compare PFS and OS in patients with high or low levels (dichotomized) of CD163 + immune cells as determined by IHC or GEX . High levels of CD163 + immune cells in the PT nest associated significantly with shorter PFS as well as with shorter OS . No significant associations were observed for CD163 + immune cells in the PT stroma . When analyzing the prognostic potential of CD163 GEX in PT from patients with MBC, high levels of CD163 GEX (expression dichotomized based on quartiles 1–3 vs. quartile 4) in the PT tended to associate with worse PFS ( P = 0.113) and OS ( P = 0.078), however these results were not statistically significant . Fig. 3 High levels of CD163 + immune cells in the tumor nest of primary tumors associate with shorter survival. Kaplan–Meier curves with log-rank test of progression-free survival (PFS; left panels) and overall survival (OS; right panels ) from baseline according to the levels of CD163 + cells in A, the primary tumor (PT) nest, B , PT stroma, or C , according to CD163 gene expression (GEX). P- values < 0.05 are highlighted in bold
|
39751847_p13
|
39751847
|
High levels of CD163 + immune cells in the primary tumor, but not in metastases, associate with worse outcome
| 4.0857 |
biomedical
|
Study
|
[
0.999396800994873,
0.0003730103198904544,
0.00023020664229989052
] |
[
0.9993758797645569,
0.0001682283909758553,
0.0003927874204237014,
0.0000631573930149898
] |
en
| 0.999997 |
When analyzing PFS and OS in relation to CD163 levels in LNM and DM by IHC and GEX, no significant associations were observed . Combined, these results indicate that CD163 + immune cells in the tumor nest of PT associate with worse outcome (PFS and OS) in MBC, while the prognostic relevance of CD163 at other tumor sites and in the PT stroma was not significant.
|
39751847_p14
|
39751847
|
High levels of CD163 + immune cells in the primary tumor, but not in metastases, associate with worse outcome
| 4.044957 |
biomedical
|
Study
|
[
0.99949049949646,
0.00027119056903757155,
0.00023830178542993963
] |
[
0.999414324760437,
0.0001892303698696196,
0.0003379543195478618,
0.00005850612069480121
] |
en
| 0.999997 |
As the breast cancer subtype also has been proposed to associate with CD163 [ 7 – 9 , 11 , 12 ], we next investigated the prognostic impact of CD163 + immune cells in the PT, stratified according to IHC-subtype as this was used to determine MBC treatment . For ER-positive MBC, high density levels of CD163 + immune cells in the tumor nest and stroma did not significantly correlate to PFS or OS . However, high CD163 GEX in ER-positive PT was significantly associated with shorter PFS and OS . As for HER2 + and triple-negative (ER − HER2 − , TNBC) subtypes, these subgroups were small with few events and therefore survival analyses were inconclusive (data not shown). Similarly, when analyzing the levels of CD163 + immune cells in LNM and DM stratified according to IHC-subtype, no conclusive results were observed due to small subgroups with few events (data not shown). Altogether, these results indicate that high levels of CD163 GEX in the PT associate with worse prognosis, primarily in ER-positive subtype. Fig. 4 High levels of CD163 GEX in the primary tumor associate with shorter survival in patients with ER + HER2 − primary tumors. Patients were stratified according to ER + HER2 − subtype of the primary tumor (PT). Kaplan–Meier curves with log-rank test of progression-free survival (PFS; left panels ) or overall survival (OS; right panels ) according to the levels of CD163 + immune cells in the A , PT tumor nest, B , PT tumor stroma, or C , CD163 GEX of PT. P- values < 0.05 are highlighted in bold
|
39751847_p15
|
39751847
|
CD163 + immune cells in primary tumors associate with survival in ER-positive MBC
| 4.099658 |
biomedical
|
Study
|
[
0.9993645548820496,
0.00040861903107725084,
0.00022679916583001614
] |
[
0.999427318572998,
0.00016693193174432963,
0.00033572549000382423,
0.00006998531171120703
] |
en
| 0.999997 |
Next, we performed uni- and multivariable Cox regression analyses to determine the potential of infiltrating CD163 + immune cells to act as an independent prognostic factor in MBC (Table 3 ). Univariable Cox regression analyses indicate that high levels of CD163 + immune cells in the PT nest associated with shorter PFS and OS ( P = 0.029, HR PFS : 1.692 95% CI: 1.056–2.712 and P = 0.007, HR OS : 1.943 95% CI: 1.200–3.144, respectively; Table 3 ). However, after adjusting for established prognostic factors in multivariable analyses, these associations were not significant. Associations between CD163 + immune cells in the tumor nest of LNM and PFS and OS were significant in multivariable analyses (Table 3 ) ( P = 0.006, HR PFS-adj : 0.361 95% CI: 0.176–0.743 and P = 0.003, HR OS-adj : 0.286 95% CI: 0.127–0.645) as well as CD163 GEX of DM and PFS and OS ( P = 0.019, HR PFS-adj : 2.551 95% CI: 1.164–5.589 and P = 0.036, HR OS-adj : 2.424 95% CI: 1.061–5.537). This should, however, be interpreted with care as these associations were not significant in univariable analyses. Due to the exploratory nature of the study, no testing for multiple comparisons (FDR or Bonferroni) were made. Altogether, these data indicate that the levels of CD163 + immune cells in the PT may identify MBC patients with worse outcome. However, these observations were not independent of other prognostic factors and the results need to be validated in a larger cohort. Table 3 Cox regression hazard ratios for the levels of CD163 + immune cells in the tumor nest and tumor stroma and CD163 GEX in relation to progression-free and overall survival Variable Progression-free survival Overall survival Hazard ratio (95% CI) Hazard ratio (95% CI) Unadjusted P -value Adjusted P -value Unadjusted P -value Adjusted P -value Primary tumor CD163 in tumor nest 1.692 (1.056–2.712) 0.029 1.558 (0.829–2.930) 0.169 1.943 (1.200–3.144) 0.007 1.219 (0.637–2.332) 0.55 CD163 in tumor stroma 1.226 (7.85–1.916) 0.371 1.220 (0.679–2.190) 0.506 1.111 (0.699–1.766) 0.657 1.014 (0.545–1.887) 0.964 CD163 GEX 1.391 (0.923–2.098) 0.115 1.528 (0.855–2.730) 0.153 1.462 (0.956–2.237) 0.08 1.767 (0.986–3.168) 0.056 Lymph node metastases CD163 in tumor nest 0.606 (0.348–1.057) 0.078 0.361 (0.176–0.743) 0.006 0.672 (0.380–1.189) 0.172 0.286 (0.127–0.645) 0.003 CD163 in tumor stroma 1.170 (0.576–2.376) 0.663 1.217 (0.433–3.421) 0.709 0.794 (0.390–1.617) 0.525 0.834 (0.307–2.268) 0.723 CD163 GEX 1.139 (0.649–2.000) 0.65 1.065 (0.417–2.724) 0.895 1.191 (0.676–2.099) 0.545 1.217 (0.407–3.639) 0.725 Distant metastases CD163 in tumor nest 1.020 (0.526–1.976) 0.953 0.661 (0.240–1.824) 0.425 0.991 (0.509–1.929) 0.979 0.658 (0.223–1.942) 0.449 CD163 in tumor stroma 1.580 (0.872–2.861) 0.132 1.158 (0.496–2.704) 0.735 1.637 (0.874–3.069) 0.124 1.105 (0.451–2.707) 0.828 CD163 GEX 1.210 (0.715–2.049) 0.478 2.551 (1.164–5.589) 0.019 1.145 (0.668–1.963) 0.623 2.424 (1.061–5.537) 0.036 Dichotomized levels of CD163 + immune cells in the tumor nest, in the tumor stroma, or of CD163 gene expression (GEX) associations with progression-free ( left ) or overall survival ( right ) in univariable (unadjusted) or multivariable analyses (adjusted for age at MBC diagnosis, ECOG performance status, NHG, breast cancer subtype based on metastases firsthand, MFI, number of metastatic sites (< 5 or ≥ 3 sites), presence of visceral metastases and the number of CTCs at MBC diagnosis (< 5 or ≥ 5 CTCs)). CI = confidence interval. P -values < 0.05 are highlighted in bold
|
39751847_p16
|
39751847
|
Uni- and multivariable Cox regression analyses
| 4.189275 |
biomedical
|
Study
|
[
0.9993230104446411,
0.0004659754049498588,
0.00021103353356011212
] |
[
0.9991724491119385,
0.00021943282627034932,
0.0005146593321114779,
0.0000934559793677181
] |
en
| 0.999996 |
Finally, in order to investigate the potential of CD163 to predict survival from the initial breast cancer diagnosis (PT diagnosis) we next compared survival (MFI plus OS from time of MBC diagnosis) in patients with high or low levels of CD163 + immune cells in the tumor nest, tumor stroma, or of CD163 GEX in the PT or synchronous LNM . In accordance with previous results, high levels of CD163 + immune cells in the PT nest ( P = 0.004, estimated median OS from PT diagnosis; high levels; 6.3 years, 2.6–9.9 95% CI and low levels; 9.2 years 8.1–10.2 95% CI, respectively), as well as the PT stroma ( P = 0.013, estimated median OS from PT diagnosis; 8.2 years, 6.8–9.7 95% CI versus 11.4 years 6.8–16.0 95% CI, respectively) were associated with worse OS (from initial diagnosis). Patterns were similar for CD163 GEX . No significant difference was observed in patients with high or low levels of CD163 + immune cells in LNM . However, high levels of CD163 GEX in synchronous LNM associated with shorter OS from the initial breast cancer diagnosis . In accordance with this, using an independent dataset comprising primary tumor GEX from 3207 patients with early breast cancer , high levels of CD163 GEX (quartiles 1–3 versus quartile 4) associated with shorter relapse-free survival and overall survival . These results indicate that the density levels of CD163 + immune cells as well as CD163 GEX in PT have potential to predict OS already at time of initial breast cancer diagnosis. Fig. 5 High levels of CD163 + immune cells in the primary tumor associate with shorter survival from primary tumor diagnosis. Kaplan–Meier curves with log-rank test of overall survival (OS) from initial primary tumor (PT) diagnosis according to infiltration of CD163 + cells in the tumor nest, tumor stroma, or CD163 gene expression (GEX) of PT ( A ) or synchronous lymph node metastases (LNM; B ). P- values < 0.05 are highlighted in bold
|
39751847_p17
|
39751847
|
High levels of CD163 + immune cells in the primary tumor associate with shorter survival from the initial breast cancer diagnosis
| 4.154256 |
biomedical
|
Study
|
[
0.9993299245834351,
0.0004435347218532115,
0.00022655738575849682
] |
[
0.9992142915725708,
0.00020446778216864914,
0.0004985971027053893,
0.00008262608025688678
] |
en
| 0.999999 |
In this study, we utilize a unique cohort to investigate how the levels of CD163 + immune cells change during tumor progression (from PT to LNM and DM) and determine the clinical relevance of CD163 + immune cells with regards to associations with clinicopathological factors and disease outcomes in MBC. To our knowledge, this is the first study to determine the prognostic potential of CD163 + immune cells in patients with MBC. Our data indicate that high levels of CD163 + immune cells in PT, but not LNM or DM, associate with adverse clinical features (including higher grade, basal-like subtype and shorter MFI) and poor outcome (PFS and OS).
|
39751847_p18
|
39751847
|
Discussion
| 4.106761 |
biomedical
|
Study
|
[
0.9993776679039001,
0.00042611302342265844,
0.00019616355712059885
] |
[
0.9994088411331177,
0.0002314050798304379,
0.00027470808709040284,
0.00008506805897923186
] |
en
| 0.999998 |
CD163 is a marker for anti-inflammatory myeloid cells, comprising predominantly TAMs but also myeloid-derived suppressor cells (MDSCs) . CD163 + immune cells are well-established players in the tumor microenvironment and several studies have reported associations with poor clinical features and outcome in primary breast cancer [ 7 – 12 ]. However, their role in metastatic disease remains unclear. We have previously shown that circulating monocytic MDSCs (Mo-MDSCs), that also may express CD163, are enriched in the peripheral blood of MBC patients and associate with adverse prognostic features . In the present study, we found that the overall distribution of CD163 + immune cells was similar between PT, LNM and DM, although statistically insignificant shifts were observed during tumor progression. High levels of CD163 + immune cells in the PT, but not LNM or DM, were associated with adverse clinicopathological variables such as higher PT grade (NHG) and basal-like and/or Luminal B subtypes. This is in agreement with previous studies in primary breast cancers reporting associations to higher histological grade and hormone-receptor negative subtype [ 7 – 12 ]. It should be noted that the PT samples in our cohort are from patients that all developed metastatic disease, which may explain the discrepancies regarding associations with Luminal B subtype from previous studies focusing only on primary breast cancer.
|
39751847_p19
|
39751847
|
Discussion
| 4.163086 |
biomedical
|
Study
|
[
0.9994478821754456,
0.00032520847162231803,
0.00022685874137096107
] |
[
0.9994015693664551,
0.0001552151661599055,
0.00036413647467270494,
0.00007908984844107181
] |
en
| 0.999996 |
This study also indicates that high levels of CD163 + immune cells in the PT nest associated with shorter MFI as well as PFS and OS in MBC patients. These observations were, however, not significant after adjusting for other established prognostic factors. In addition, both high protein levels (IHC data) and GEX of CD163 in PT strongly associated with shorter survival from the time of the initial breast cancer diagnosis (PT diagnosis). The association between high levels of CD163 GEX and shorter survival was also validated in an independent dataset of patients with primary, early breast cancer. Interestingly, the levels of CD163 + immune cells in PT had a stronger association to prognosis than levels in DM. While the patterns of prognostic potential of CD163 appear to be different in PT and DM, it is important to note that analyses of PT are better powered due to larger sample size.
|
39751847_p20
|
39751847
|
Discussion
| 4.083322 |
biomedical
|
Study
|
[
0.9994244575500488,
0.00035353313433006406,
0.0002220709720859304
] |
[
0.9994124174118042,
0.00015975924907252192,
0.0003549445536918938,
0.00007296921103261411
] |
en
| 0.999996 |
The observation that CD163 + immune cell levels of the PT are of prognostic value also for MBC has several important potential future implications that should be further investigated. CD163 may add prognostic information in MBC, as it identifies a subgroup of patients with worse prognosis that could benefit from more frequent monitoring and potential treatment adjustments. Furthermore, although molecular profiling of distant metastases guides the treatment strategy in MBC today, material from metastases may not always be available. Thus, the possibility to use information regarding CD163 + immune cells in PT tissue is of clinical relevance. In line with this, our recent study from the same MBC cohort indicated that the GEX profile of the PT is as useful as the DM for predicting outcome in MBC . In addition, the possibility of targeting CD163 + immune cells, potentially already at the time of the PT diagnosis, may pose an interesting and future treatment strategy to prevent MBC and prolong survival. CD163 is upregulated in several conditions, ranging from acute and chronic inflammatory diseases to malignancies . Current efforts in targeting CD163 + immune cells focus on anti-CD163 antibodies directly conjugated to cytotoxic drugs or anti-CD163 coated liposomes loaded with drugs. These studies have shown effects in reducing tumor growth and affect the local immune composition, as well as to reduce the metastatic spread in mouse models of cancers such as melanoma and ovarian carcinoma . The findings that CD163 GEX hold prognostic value also in ER-positive MBC is highly relevant since most immunotherapies currently used are primarily aimed at TNBC. To further explore the role of CD163 + immune cells in the different molecular subtypes is therefore of importance.
|
39751847_p21
|
39751847
|
Discussion
| 4.27312 |
biomedical
|
Study
|
[
0.9993977546691895,
0.0003984193317592144,
0.00020384987874422222
] |
[
0.9921035766601562,
0.0004333809483796358,
0.007310884539037943,
0.00015212390280794352
] |
en
| 0.999997 |
This study makes use of a unique cohort of matched tissue samples (PT, LNM and DM) providing both GEX and IHC analyses, from 139 MBC patients planned for first line systemic therapy with long-term follow-up. One limitation is the cohort size, and the analyses performed should thus be considered exploratory. Our data should be validated in a larger MBC cohort to facilitate subgroup analyses of CD163 + immune cells in different molecular subtypes of MBC as well as in metastases from distinct localizations (e.g., in bone or liver metastases). Understanding the immunological heterogeneity in metastases compared to PT will be of great importance for improving current prognostic tools as well as for future individualized therapeutic strategies.
|
39751847_p22
|
39751847
|
Discussion
| 4.09674 |
biomedical
|
Study
|
[
0.9994322657585144,
0.00037293892819434404,
0.000194747161003761
] |
[
0.9993782043457031,
0.000191714774700813,
0.00035164508153684437,
0.00007834228017600253
] |
en
| 0.999997 |
To conclude, high levels of CD163 + immune cells as well as CD163 GEX in the PT rather than in metastases associate with adverse clinicopathological factors and shorter PFS and OS in MBC as well as with shorter OS from time of initial PT diagnosis. However, these associations were not significant after multivariable analyses adjusting for other established prognostic factors. These results indicate that CD163 + immune cells in the PT may have potential to add prognostic information for clinical outcome in MBC patients, however there is need for validation in larger cohorts.
|
39751847_p23
|
39751847
|
Discussion
| 4.040417 |
biomedical
|
Study
|
[
0.9995077848434448,
0.0002861056418623775,
0.00020615318499039859
] |
[
0.9989331364631653,
0.00019959663040935993,
0.0007932455046102405,
0.00007409950922010466
] |
en
| 0.999996 |
Below is the link to the electronic supplementary material. Supplementary file1 Supplementary file2 (PDF 15 KB)
|
39751847_p24
|
39751847
|
Supplementary Information
| 1.044671 |
other
|
Other
|
[
0.25596269965171814,
0.002776938956230879,
0.7412604093551636
] |
[
0.009049717336893082,
0.9894145727157593,
0.0010167993605136871,
0.0005188941140659153
] |
en
| 0.999997 |
A short-pulse laser-driven neutron source (LDNS) offers a compact, bright, and relatively inexpensive way of producing high-intensity neutron-beam pulses that can be used for a variety of basic and applied scientific needs 1 – 27 . LDNSs typically operate by directing an intense ion-beam of protons or deuterons driven by a high energy, high-intensity laser into a suitable material acting as a fast (~ MeV) neutron converter via a suitable nuclear reaction, the so-called pitcher-catcher configuration. Since the ion-beam pulse is very short in duration (~ 1 ps at birth), placing the converter close to the laser target (~ 1 cm) yields a fast neutron burst (~ 1 ns). The kinematics of the nuclear reactions of the ion-beam in the converter gives predominantly forward directionality (~ 1 sr) to the neutron source. Using the Trident laser facility at Los Alamos National Laboratory (LANL), an advancement in the yield and efficiency (and therefore fluence and intensity) of laser-driven neutron-beam sources was demonstrated 4 , 15 by driving deuteron ion beams in the relativistic transparency regime of laser-plasmas (the Breakout Afterburner (BOA) ion-acceleration mechanism) 13 , 28 . At the Trident laser facility, a sub-ps laser beam was focused to a peak intensity of 10 21 W/cm 2 on an ultra-thin (sub-micron) deuterated plastic foil target, to drive a high-energy deuteron ion beam, which was directed onto a beryllium converter disk placed behind the foil to produce a neutron beam via nuclear breakup reactions. This neutron source features both high intensity and predominantly forward directionality, both of which are operationally useful. Yields of > 10 10 fast neutrons per sr per shot, peaked in the forward direction, with extremely short neutron pulse duration (~ 1 ns) can be routinely produced 4 , 5 , 17 , 20 , 21 .
|
39753631_p0
|
39753631
|
Introduction
| 4.379639 |
biomedical
|
Study
|
[
0.9982852339744568,
0.00031470711110159755,
0.001400033594109118
] |
[
0.9979032278060913,
0.0008051161421462893,
0.0012159638572484255,
0.00007561530219390988
] |
en
| 0.999997 |
A principal motivation for such a source was the capability to perform nondestructive assay (NDA) of special nuclear material (SNM) for nuclear material accountancy, nuclear safeguards, and national security applications in entirely new ways that are enabled by the unprecedented fast-neutron intensity in a single brief fast-neutron pulse 5 .
|
39753631_p1
|
39753631
|
Introduction
| 2.174113 |
biomedical
|
Other
|
[
0.6621487140655518,
0.001142178662121296,
0.33670908212661743
] |
[
0.1384892761707306,
0.8600543737411499,
0.0009345345315523446,
0.0005218652077019215
] |
en
| 0.999997 |
The introduction of such sources promises to transform many research and technological areas. The extensive review of Diven 29 outlined the unique potential of the intense neutron flux from nuclear explosions to survey neutron cross sections and make unique measurements. Specifically, he describes the salient features, advantages and limitations of intense short-duration single-pulse ‘white’ neutron sources for time-resolved studies. LDNS sources allow for a reimagining of these possibilities on a more manageable, deployable, and feasible scale, as well as other traditional pulsed neutron generator application areas, such as those built around TRIGA burst-reactors, and large-scale accelerators 30 , 31 . To realize the potential of pulsed laser sources, understanding and controlling the beam characteristics is critical, as is mastery of how to adapt and optimize nuclear measurement instruments and methods to specific real-world problems such as the assay of special nuclear materials.
|
39753631_p2
|
39753631
|
Introduction
| 4.0339 |
biomedical
|
Review
|
[
0.9814707636833191,
0.001668886048719287,
0.01686037704348564
] |
[
0.019559074193239212,
0.003643002361059189,
0.9765092730522156,
0.00028870441019535065
] |
en
| 0.999997 |
The detection, characterization, and quantification of nuclear materials is an evolving technological challenge being advanced by, for example, non-proliferation and anti-terrorism programs 32 . The detection of shielded special nuclear materials, including nuclear explosives 33 , to assist with interdiction of trafficking is a major concern, as too is the ability to perform materials analysis and energy-resolved neutron radiography 21 , 26 , 27 . In this context, active interrogation is particularly important for the detection of uranium as the passive emissions are relatively weak.
|
39753631_p3
|
39753631
|
Introduction
| 3.422209 |
biomedical
|
Study
|
[
0.8455871939659119,
0.0006282231188379228,
0.1537846475839615
] |
[
0.637513279914856,
0.3488345742225647,
0.013192286714911461,
0.0004598923842422664
] |
en
| 0.999997 |
LDNS technology offers important advantages over existing neutron sources such as deuteron-tritium (DT) neutron generators 34 or sealed radionuclide neutron sources (typically 252 Cf spontaneous fission or AmLi (α,n) neutron sources), which have been the main sources available in the past for interrogation applications. These advantages are based on the ability to deliver in a single shot a relatively high yield of fast neutrons in a short burst over a relatively small solid angle, i.e., an intense, directed or ‘beamed’ neutron burst. Moreover, the technology exists for the relevant high-energy, high-power lasers to run at 10 Hz, allowing the possibility of accumulating yield rapidly to buildup information to meet a given data quality objective (see Discussion section, “Further work towards a production system”). The directionality of the neutron source provides an advantage in personnel safety and material activation concerns relative to isotropic sources with the same assay flux because of the simpler shielding considerations and higher useful neutron fraction. High intensity enables a high signal-to-noise ratio measurement in difficult situations such as the high background neutron emission rate from irradiated nuclear fuel. High yield enables short assay times, which translates to a high item throughput, which can be important in industrial settings. In addition, application-specific tailoring of the interrogating neutron energy spectrum and the emission angular distribution is possible and advantageous. For example, tailoring the neutron energy to lie in the range of a few MeV up to several tens of MeV allows relatively deep penetration into heavy (high Z) shielding materials, which poses an extreme challenge for γ-ray based interrogation technology. While high-power, high-energy lasers are not physically small, the technology exists to make them moveable for flexibility in the deployment of this high-value asset. The laser beam itself can be readily transported over relatively long distances (~ 10–100 m) into the vacuum chamber containing the laser-target and neutron converter. In a production (rather than research) environment, that chamber can be small with minimal footprint in the interrogation bay, providing flexibility and minimizing cost and complexity.
|
39753631_p4
|
39753631
|
Introduction
| 4.361517 |
biomedical
|
Study
|
[
0.9986079335212708,
0.00032440785435028374,
0.0010676473611965775
] |
[
0.964857816696167,
0.003154566278681159,
0.031800150871276855,
0.00018740732048172504
] |
en
| 0.999998 |
Active neutron interrogation of nuclear materials involves measurements of neutron induced signatures to identify/assay SNM during and after an interrogation with an external neutron pulse 35 , 36 . The concepts and theoretical foundation of methods for such interrogation have been long established 36 but over the past few decades, practical realization has been made easier by the availability of powerful yet compact multi-parameter data acquisition chains and high-speed large-memory computers for experimental simulation and data analysis. A limiting factor is the availability of compact, reliable, bright neutron sources with favorable characteristics (pulse width, intensity, energy, and angular distribution), which has motivated the interest and vigorous research on laser-based neutron sources.
|
39753631_p5
|
39753631
|
Introduction
| 4.057821 |
biomedical
|
Study
|
[
0.9838382005691528,
0.00021019051200710237,
0.01595156639814377
] |
[
0.9736922383308411,
0.007739468943327665,
0.0184810608625412,
0.00008720930782146752
] |
en
| 0.999996 |
The neutron-induced signatures of interest include prompt and delayed fission neutrons emitted by the assayed item. The prompt and delayed components are defined here as corresponding to < 1ms following the interrogating neutron pulse for the former and > 1ms for the latter. The definition of prompt and delayed component timing varies in the literature. The one used in this paper is selected to separate any effects of the interrogating neutron pulse from the delayed neutron emission signal. This includes detector deadtime following the neutron pulse, room return of scattered near-thermal neutrons, and additional effects, all further discussed in the paper. Two active neutron interrogation techniques employed in current nuclear safeguards applications include differential die-away assay (DDA) 35 and delayed neutron assay (DN) 37 , designed to exploit the neutron signatures in the prompt and delayed time intervals, respectively. Delayed neutrons (emitted isotropically following β-decay, hence “β-delayed”) represent a particularly attractive signature to detect SNM, since very few other processes besides nuclear fission yield neutrons on similar timescales giving the method high analytical specificity. Although the delayed neutron yield is only a few percent of the prompt yield, the time delay allows the neutron-signal from the interrogation neutron pulse to dissipate before the delayed neutrons are counted, which greatly improves the signal-to-noise.
|
39753631_p6
|
39753631
|
Introduction
| 4.231965 |
biomedical
|
Study
|
[
0.9989323019981384,
0.00023253682593349367,
0.0008350642747245729
] |
[
0.9991284012794495,
0.00028135505272075534,
0.0005513405194506049,
0.00003892715540132485
] |
en
| 0.999998 |
Active neutron interrogation has been studied extensively and is implemented widely, with a primary focus so far being the measurement of low amounts of SNM in radioactive waste 38 . Generally, the interrogation is performed via pulsing a D-T neutron generator, with a frequency typically around 100 Hz and neutron intensities of the order of ~ 10 8 n/s. The prompt and delayed fission neutrons are then detected in 3 He-filled proportional counters 34 – 37 .
|
39753631_p7
|
39753631
|
Introduction
| 4.001087 |
biomedical
|
Study
|
[
0.9877393841743469,
0.00018908367201220244,
0.012071541510522366
] |
[
0.986331582069397,
0.009986459277570248,
0.003605432575568557,
0.00007650609768461436
] |
en
| 0.999996 |
The concept of active interrogation using a laser-driven neutron source is presented in Fig. 1 . A laser interacts with a deuterated polystyrene (CD) target and produces deuterons (D beam), subsequently converted into a neutron beam in a Be puck. The neutron beam is then used for active interrogation of a concealed nuclear material object (here shown as a suitcase). The detection of induced fission neutrons is a signature of the presence of nuclear material and is used to assay the nuclear material in the object.
|
39753631_p8
|
39753631
|
Introduction
| 3.974483 |
biomedical
|
Study
|
[
0.9981726408004761,
0.00030359174706973135,
0.0015238323248922825
] |
[
0.9305209517478943,
0.06787726283073425,
0.001299605006352067,
0.00030215998413041234
] |
en
| 0.999997 |
Fig. 1 The concept of active interrogation using a laser-driven neutron source is presented. The objects being interrogated can vary in size, ranging from small items like suitcases to large objects such as freight containers.
|
39753631_p9
|
39753631
|
Introduction
| 1.366008 |
other
|
Other
|
[
0.10397695004940033,
0.0011603625025600195,
0.8948627710342407
] |
[
0.02439737692475319,
0.973800778388977,
0.001258048927411437,
0.0005438965745270252
] |
en
| 0.999999 |
Dedicated experiments were conducted at LANL to assess a short-pulse LDNS for active interrogation of uranium materials. Exploration by direct experiment is presently necessary because a comprehensive end-to-end modeling tool from the laser plasma to the neutron output does not exist yet. Moreover, the impact of the unique radiation environment created by this novel source on the measurements on which a successful active interrogation strategy depends could not be confidently ascertained a priori. Experiments are, therefore, essential in both the development of active interrogation concepts and the associated simulation tools. Pursuant to that end, the experimental results obtained for enriched uranium using the β-delayed neutron counting technique are presented and discussed here. These measurements have provided the first-of-a-kind experimental demonstration of active interrogation using a high-intensity short-pulse laser-driven neutron source and demonstrate the feasibility of interrogation using a single laser-driven neutron pulse.
|
39753631_p10
|
39753631
|
Introduction
| 4.119757 |
biomedical
|
Study
|
[
0.9659442901611328,
0.0004654634394682944,
0.03359021246433258
] |
[
0.9989297986030579,
0.0007835326832719147,
0.00024040490097831935,
0.00004619239552994259
] |
en
| 0.999996 |
The experiments were carried out at the 200 TW Trident laser facility at LANL in the setup shown in Fig. 2 .
|
39753631_p11
|
39753631
|
Results
| 1.842111 |
biomedical
|
Study
|
[
0.6961467862129211,
0.0017188359051942825,
0.30213433504104614
] |
[
0.6503304243087769,
0.34609949588775635,
0.0024548571091145277,
0.0011152648366987705
] |
en
| 0.999996 |
Fig. 2 Set-up of the experiment (detector sizes and placement not to scale). The red item inside one of the 3 He-based AWCC neutron detectors is a sample of special nuclear material. AWCC counters were positioned on the equator with their open end facing towards the neutron converter, closely straddling the central beam axis at an angle of ~ 10 degrees from that axis.
|
39753631_p12
|
39753631
|
Results
| 2.491596 |
biomedical
|
Study
|
[
0.8788192272186279,
0.0015062529128044844,
0.11967453360557556
] |
[
0.7124240398406982,
0.2857537269592285,
0.001083532115444541,
0.0007387439836747944
] |
en
| 0.999998 |
The evacuated target chamber (20 mm thick stainless steel, 1 m in diameter) is equipped with Al flanges for equipment insertion and user access. It housed the laser turning mirror and focusing optics for the 9-inch (~ 229 mm) diameter laser beam. The chamber also housed the assembly for target support and positioning, the laser target, and the ion-to-neutron converter, of ~ 100 mm dimension overall. The laser focusing optic used in the present experiment was an f/1.5 off-axis parabolic mirror with a high-reflectivity Hf-coating for the 1.053 μm laser wavelength . The typical 80 J high-contrast 39 0.6 ps laser pulses (FWHM) reached a peak vacuum intensity of ≈10 21 W/cm 2 . The targets for this run were spin-coated polystyrene (CD) nanofoils 1 g/cm 3 with thickness in the range of 0.6–0.75 μm, in order to access the Break-out Afterburner (BOA) laser-driven acceleration mechanism 39 for the D-beam of interest in these experiments. A key to realizing this ion-acceleration regime on Trident was its high-contrast laser front end 39 , because without sufficiently high laser-pulse contrast, the pre-pulse and main-pulse pedestal would destroy such thin targets. The repetition rate in these experiments was approximately one shot about every 90 min. This rate was solely dictated by proper cooldown of the laser-amplifier glass in the last amplifier stage, which is flash-lamp pumped in this decades-old design.
|
39753631_p13
|
39753631
|
Results
| 4.22643 |
biomedical
|
Study
|
[
0.9963451027870178,
0.0004300084838178009,
0.0032249270007014275
] |
[
0.9986467957496643,
0.0011435386259108782,
0.00015331468603108078,
0.00005635217530652881
] |
en
| 0.999998 |
The resulting high-energy D beam is directed at the ion-to-neutron converter. The converter consisted of a stack of Be cylinders 50 mm in diameter totaling 6 mm to 15 mm in thickness with their axes aligned along the laser-propagation direction (i.e., the ion-beam cone axis). The laser-facing end of the cylinder stack was located 38 mm downstream from the laser target and protected from the plasma and the transmitted light by Kapton tape to avoid damage and Be dispersal in the chamber.
|
39753631_p14
|
39753631
|
Results
| 3.850768 |
biomedical
|
Study
|
[
0.9844498038291931,
0.0005616256385110319,
0.01498856395483017
] |
[
0.9146366119384766,
0.08471741527318954,
0.00038334247074089944,
0.00026264882762916386
] |
en
| 0.999998 |
The neutron diagnostic equipment, placed outside the vacuum target chamber, included one neutron time-of-flight (nTOF) detector system to measure the energy distribution of the laser-driven fast neutron production and two existing high-efficiency thermal-neutron well-counters (Active Well Coincidence Counters [AWCCs]) to measure the neutron emission from the SNM items. In this proof-of-principle experiment, rather than develop and qualify custom delayed-neutron detectors, as would be justifiable in a dedicated interrogation system, we used existing hardware for convenience. Indeed, AWCCs of this type are routinely used by the international nuclear safeguards and security communities to assay U and Pu by other means 40 , 41 . The AWCCs have a hollow cylindrical cavity where the interrogated sample may be placed. To unambiguously demonstrate the β-decay-delayed neutron signature following fission, the experimental campaign involved a comparative evaluation, where two identical detectors were used; one contained the interrogated sample (master counter), while the other remained empty and served as a reference (reference counter). Each of the AWCCs is equipped with 42 4-atm 3 He-filled proportional tubes, each 25.4 mm in outer diameter, embedded in high-density polyethylene (HDPE). The tubes are arranged in two concentric rings surrounding the central well. In their standard configuration, each AWCC is equipped with top and bottom HDPE inserts that are used to minimize neutron leakage from the sample well. During the current experimental campaign, the detectors were oriented sideways (i.e., with their ‘top’ opening facing the laser target) to fully expose the interrogated material to the laser-produced neutron beam. In this arrangement, the top and bottom HDPE inserts were removed to allow for maximum penetration, even for the low-energy neutron beam component. To ensure identical measurement conditions for both detectors during the interrogation measurements, both detectors were positioned symmetrically relative to the axis of forward directed neutron beam, with the respective detector axes pointing toward the source . Each AWCC is also equipped with a thin (~ 1 mm) Cd liner in the cavity, which blocks the contribution of slow (energies below about 0.4 eV) neutrons returning into the detector cavity after moderation in HDPE. Otherwise, such moderated fast fission neutrons from the sample returning to the cavity could induce additional fission in the sample resulting in an additional delayed-neutron signal. Thus, the AWCC has two operating modes: ‘fast mode’ (interrogation with fast neutrons) with the Cd liner in place and ‘thermal mode’ (interrogation with mainly thermal neutrons) with the Cd liner removed. The former case is suitable for interrogation of large quantities of U (0.1–20 kg). In the latter case, the sensitivity of the counter is greatly enhanced (due to the large thermal 235 U fission cross section) that makes the counter more suitable for interrogation of small or low-enriched uranium materials (0–100 g of 235 U). Both modes were investigated in the current experimental campaign.
|
39753631_p15
|
39753631
|
Results
| 4.262543 |
biomedical
|
Study
|
[
0.9985387325286865,
0.00044974518823437393,
0.0010115642799064517
] |
[
0.9993696808815002,
0.00031040015164762735,
0.0002634002885315567,
0.00005652833715430461
] |
en
| 0.999998 |
Three ~ 900 g uranium samples with enrichments of 12%, 38%, and 66% of 235 U were used. Both of the AWCCs used in the experiment were thoroughly characterized prior to the laser-driven interrogation measurements as explained in the Methods section.
|
39753631_p16
|
39753631
|
Results
| 2.566344 |
biomedical
|
Study
|
[
0.9418373107910156,
0.0007063173688948154,
0.0574563629925251
] |
[
0.985345184803009,
0.014100687578320503,
0.0003586961829569191,
0.00019545253599062562
] |
en
| 0.999997 |
In the following, firstly, we provide the characterization of the laser-driven neutron source (the interrogation source), and secondly, we report on the demonstration of the active interrogation of SNM.
|
39753631_p17
|
39753631
|
Results
| 2.447253 |
biomedical
|
Study
|
[
0.8684939742088318,
0.0010843422496691346,
0.1304217129945755
] |
[
0.9454776048660278,
0.053061604499816895,
0.0010246142046526074,
0.0004362043982837349
] |
en
| 0.999998 |
Fig. 3 Neutron energy spectrum as extracted by the measurements of neutron-time-of-flight of the 36.7 ± 0.6 mrem shot with 700 nm CD target thickness and 6 mm Be thickness, 80.5 J on target. The energy spectrum approximately exhibits a power-law distribution, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\:\sim{E}^{-2.42}$$\end{document} , where E is the kinetic energy of the neutrons in MeV.
|
39753631_p18
|
39753631
|
Neutron production
| 3.987739 |
biomedical
|
Study
|
[
0.9351910948753357,
0.00048239718307740986,
0.06432656198740005
] |
[
0.9952238202095032,
0.004452614113688469,
0.0002596880658529699,
0.0000639109275653027
] |
en
| 0.999995 |
A neutron time-of-flight (nTOF) detector system was located outside the building at 6.2 m from the neutron beryllium converter. That location made it possible to measure the high energy component of the neutron spectrum with good resolution (due to the distance), to separate in time the signal from the prompt “gamma flash” (the burst of X-rays from the laser-plasma interaction) to allow recovery of the photomultiplier tube detector and electronics, and to avoid the problem with neutron signals in the detector coming from scattering neutrons in the experimental room.
|
39753631_p19
|
39753631
|
Neutron production
| 3.688071 |
biomedical
|
Study
|
[
0.926140546798706,
0.0005829822621308267,
0.07327647507190704
] |
[
0.9061660766601562,
0.09307638555765152,
0.000523116672411561,
0.00023436202900484204
] |
en
| 0.999997 |
The absolute neutron yield per pulse was measured for each shot using bubble detectors positioned around the chamber, including the target chamber exit flange directly on axis in the forward direction of the neutron beam. The bubble detectors are sensitive to neutrons with energy from a few 100’s of keV up to 100’s of MeV 11 . The determination of the absolute neutron yield per sr from the bubble detector and TOF diagnostics is explained in the Methods section.
|
39753631_p20
|
39753631
|
Neutron production
| 3.897729 |
biomedical
|
Study
|
[
0.9964633584022522,
0.00025602924870327115,
0.0032806266099214554
] |
[
0.9983022212982178,
0.0014418477658182383,
0.00018996042490471154,
0.00006591450073756278
] |
en
| 0.999997 |
Figure 3 shows the derived neutron energy spectrum (see the Methods section) for laser shot 25,424, where a 700 nm thick CD target, and 6 mm Be converter were used, with 80.5 J of laser energy on target, and a neutron dose of 36.7 ± 0.6 mrem (1-σ) was produced (determined by averaging bubble detection readings from bubble detectors with low and high sensitivity, see Methods , located at the exit flange). The energy spectrum resembles a power law, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\:dN/dE\sim{E}^{-2.42}$$\end{document} with E being the kinetic energy of neutrons in MeV, up to about 3 MeV, with a residual of very fast neutrons with energies extending up to ~ 50–100 MeV. The energy spectrum presented is typical of our shots 42 . In the same campaign (for active interrogation) we achieved reproducibility of shots at the same neutron dose level .
|
39753631_p21
|
39753631
|
Neutron production
| 4.165785 |
biomedical
|
Study
|
[
0.9984232187271118,
0.0003080622700508684,
0.0012687522685155272
] |
[
0.9995191097259521,
0.00028775454848073423,
0.0001480394566897303,
0.00004511445149546489
] |
en
| 0.999998 |
The neutron dose of 36.9 mrem at the exit flange corresponds to a neutron yield of (2.1±0.3) ×10 10 neutrons/sr in the neutron energy interval 0.2 MeV to 92.4 MeV, once the neutron spectrum and the dose-to-yield conversion curve for the bubble detectors are used (see Methods). The uncertainty includes the estimated contributions from the bubble detector reading, the spectrum deconvolution process, and the interpolation of the bubble detector dose-to-yield conversion curve. The yields for the shots reported above are all above 2.0 × 10 10 neutrons/sr. The consistent and reproducible high-intensity neutron yield per shot reported here is the result of incremental improvements in laser operations and target instrumentation. These improvements have optimized beam readjustment, and enhanced target alignment, leading to improved performance in neutron generation 43 . The ability to extract the actual neutron energy spectrum and improvements in target thickness and Be converter radius design have also contributed to the reported performance.
|
39753631_p22
|
39753631
|
Neutron production
| 4.19343 |
biomedical
|
Study
|
[
0.9987770915031433,
0.00029120713588781655,
0.0009316321811638772
] |
[
0.9994180202484131,
0.0002612920943647623,
0.00027083646273240447,
0.000049940761527977884
] |
en
| 0.999999 |
In the present experiments, the two AWCC neutron detectors were positioned in a direct line of sight of the forward portion of the neutron beam . One contained the interrogated material in its central well, while the other served as an empty reference or blank for comparison. The campaign comprised a series of individual laser-driven neutron pulses, each a few ns in duration, separated by approximately 90 min required for replacement of the laser-target, cool-down of the laser, re-alignment of the laser beam (if needed), and pumping the vacuum chamber. Data from the AWCC detectors were acquired in the form of timestamps corresponding to every neutron detection event using a PTR-32 list mode data acquisition unit 5 . The PTR-32 is a multi-input device that records neutron detection times (leading edge of the logic pulses from the charge-amplifier-discriminator circuit attached to the 3 He proportional counters) with a resolution between two subsequent detection events of 10 ns. This data format allows for direct investigation of the temporal behavior of detected neutrons following an interrogating neutron pulse and enables a direct visualization of the delayed neutron signature in the detected neutron pulse stream.
|
39753631_p23
|
39753631
|
Detection of nuclear material by active interrogation
| 4.187784 |
biomedical
|
Study
|
[
0.9984797835350037,
0.00028045332874171436,
0.0012398018734529614
] |
[
0.9994543194770813,
0.00030196536681614816,
0.00020729898824356496,
0.00003634695531218313
] |
en
| 0.999998 |
The delayed neutrons represent a characteristic signature of induced fission in the interrogated material and as such represent a key manifestation of the presence of SNM. The delayed neutron emission takes place when a β-decay nucleus (precursor) decays and the resulting daughter-nucleus emits a neutron. Delayed neutron emissions are commonly classified into six effective temporal groups (based on the contributory delayed neutron precursor half-lives and intensities) characterized by average half-lives between 0.2 and 56 s 44 . During the laser-driven active interrogation campaign, each laser-driven neutron pulse was followed by several minutes of data acquisition to allow sufficient time for all delayed neutron groups to fully decay and be recorded. Time-interval distributions of detected neutrons from the master and reference AWCC detectors were then constructed from the acquired data to evaluate the delayed neutron signature.
|
39753631_p24
|
39753631
|
Detection of nuclear material by active interrogation
| 4.146923 |
biomedical
|
Study
|
[
0.9963679313659668,
0.0003020961012225598,
0.003330025589093566
] |
[
0.9993219375610352,
0.0004558563232421875,
0.00018777570221573114,
0.0000345058724633418
] |
en
| 0.999995 |
To illustrate the key features of the delayed neutron signature recorded in the AWCC detectors, the time distributions from laser-driven neutron interrogation of the 38% enriched uranium item are shown in Fig. 4 The distributions shown represent raw time distribution plots (not normalized to neutron yield) as recorded following two individual laser pulses with the two modes of AWCC operation – fast and thermal . Red lines in the figure represent results from the master AWCC, while the time-interval distributions from the empty, reference AWCC are shown as black dotted lines. The sharp peak at the beginning of the time-interval distributions corresponds in time to the interrogating neutron pulse and is followed by a delayed component shown here on a timescale of 200 s. A net enhancement of the delayed neutron component in the time distributions is clearly visible compared to the empty reference AWCC. Insets in Fig. 4 provide a more detailed view of the delayed neutron signature over a timescale of 50 s.
|
39753631_p25
|
39753631
|
Detection of nuclear material by active interrogation
| 4.073046 |
biomedical
|
Study
|
[
0.9191597104072571,
0.0006965207285247743,
0.08014373481273651
] |
[
0.9987842440605164,
0.0008794373134151101,
0.00028710730839520693,
0.00004932095544063486
] |
en
| 0.999999 |
As discussed in the previous section, the operation of the AWCC in the thermal mode offers greater sensitivity and so allows interrogation of smaller quantities of 235 U (where self-shielding is reduced and thermal neutrons can interrogate the material effectively). In this configuration, the Cd liner of the inner wall of the central measurement well is removed, allowing for additional neutrons thermalized in the moderator to reach the item. This enhanced thermal neutron component also explains the increased delayed neutron signal observed in Fig. 4 bottom for the AWCC operated in the thermal mode for the same amount of interrogated SNM.
|
39753631_p26
|
39753631
|
Detection of nuclear material by active interrogation
| 3.95241 |
biomedical
|
Study
|
[
0.9488897919654846,
0.0004714589158538729,
0.050638698041439056
] |
[
0.9909895658493042,
0.008532071486115456,
0.0003875952970702201,
0.00009068386862054467
] |
en
| 0.999996 |
Fig. 4 Time-interval distributions over 200 s following the laser trigger; (full red line) master AWCC containing 38% enriched U sample; (dotted black line) the empty, reference AWCC. AWCC detectors were operated in the ‘fast mode’ (top) and the ‘thermal mode’ (bottom). The insert highlights the detail of the time-interval distribution over 50 s following the trigger.
|
39753631_p27
|
39753631
|
Detection of nuclear material by active interrogation
| 2.456983 |
biomedical
|
Study
|
[
0.7899704575538635,
0.0012036894913762808,
0.20882584154605865
] |
[
0.8913020491600037,
0.1071222797036171,
0.0010630821343511343,
0.0005126151954755187
] |
en
| 0.999998 |
A closer look at the time-counting distributions from the reference AWCC, the one that contains no SNM and therefore no induced delayed fission neutrons, nevertheless reveals the presence of a delayed neutron component that decays away on significantly shorter timescales (order of 1 s) than the delayed signal observed in the other (master) AWCC that does contain uranium. This fast-decaying delayed signature was extensively studied in the previous laser-driven neutron production campaign 5 . It was identified as neutrons from the decay of 9 Li produced in the Be converter under irradiation by high-energy deuterons from the target as well as via interactions with the subsequent high-energy produced neutrons. The 9 Li production reactions are 9 Be(d,2p) 9 Li and 9 Be(n, p) 9 Li with thresholds of 18.4 MeV and 14.3 MeV, respectively, with the (d,2p) reaction being the dominant channel. 9 Li is known to produce delayed neutrons with a half-life of 178.3 ms which matches the trace from the reference AWCC in Fig. 4 . Importantly, the 9 Li delayed neutron yield can serve as a laser-driven-ion diagnostic and this realization opens up a new avenue of research to support both experimental and theoretical developments. Distinct from this fast-decaying delayed component, the signal from the AWCC containing the SNM sample exhibits a delayed neutron signature over a much longer timescale consistent with the timescale of delayed fission neutrons. The delayed neutron emission was analyzed over a 200-second interval starting 1 s after the laser pulse. The 1-second delay was used to reduce the impact of the 9 Li delayed neutron component since it corresponds to ~ 6× the 9 Li half-life.
|
39753631_p28
|
39753631
|
Detection of nuclear material by active interrogation
| 4.261768 |
biomedical
|
Study
|
[
0.9970122575759888,
0.00041188005707226694,
0.0025759523268789053
] |
[
0.9994844198226929,
0.00023421082005370408,
0.00023330126714427024,
0.00004801371687790379
] |
en
| 0.999998 |
It should be emphasized that one of the key features of the LDNS based on the relativistic transparency acceleration mechanism is the production of a high-intensity, mostly forward-peaked, neutron pulse (> 10 10 n/sr in this campaign), which has the potential to provide a statistically significant (high precision) delayed neutron signature in a single pulse. The time distributions presented illustrate this capability in an unambiguous way. This is the first demonstration of this new analytical capability.
|
39753631_p29
|
39753631
|
Detection of nuclear material by active interrogation
| 3.02592 |
other
|
Study
|
[
0.3780185580253601,
0.0009754706989042461,
0.6210058927536011
] |
[
0.9228983521461487,
0.0756034106016159,
0.0010948594426736236,
0.0004033432633150369
] |
en
| 0.999999 |
The initial laser-target interaction is accompanied by an intense flash of X-rays 11 , and the potential contribution of high energy X-ray-induced fissions to the measured delayed neutron signature was evaluated. Photofission cross sections for 235 U and 238 U have an energy threshold of about 8 MeV, with a resonance behavior up to about 15 MeV. The cross-section peak value is, however, an order of magnitude less than the cross-section of neutron-induced fission in the same range of energy (10–20 MeV). A dedicated measurement was performed with 2 kg of depleted uranium (DU) material inside a high-level neutron coincidence counter version II (HLNCC-II) that is conceptually similar to an AWCC, but smaller and with less neutron efficiency 5 , 45 . The DU material was used bare and then subsequently shielded by a 10 cm thick Pb blocks to significantly reduce the (potential) contribution of X-rays to the induced fissions of depleted uranium without having a large effect on the transmitted fast-neutron neutron flux. The integral delayed neutron counts were normalized to bubble chambers located inside the HLNCC-II and were then evaluated for both DU configurations. The measured ratio of the bare versus shielded DU configuration corresponded to (1.00 ± 0.29), where the uncertainty is estimated as the 1-σ level. This suggests that any amount of fission caused by the X-rays is small (as expected). In order to improve the precision of the results a second experiment was performed with an intense laser-driven X-ray flash, obtained by substituting the CD-laser target with 238 U disk targets (thickness 350 μm diameter 90 μm). The laser-driven electron distribution interacting with this thicker, high Z target gives an increase of magnitude in radiative losses (scaling with Z 2 and density from CD to U) and so in the bremsstrahlung production of X-rays 46 . Such a flash was used to illuminate the 38% 235 U enriched item, and the subsequent delayed neutron production was measured. The delayed neutrons production from this X-ray flash is only 2% of the DN production from a typical 30 mrem neutron shot. This result demonstrates the negligible effect of X-ray-induced fissions on the delayed neutron signature and confirms that neutron-induced fissions are the overwhelming source of the observed delayed neutron signal.
|
39753631_p30
|
39753631
|
Detection of nuclear material by active interrogation
| 4.346329 |
biomedical
|
Study
|
[
0.9987347722053528,
0.0004443600482773036,
0.0008208730141632259
] |
[
0.9993906021118164,
0.00021841189300175756,
0.0003198842459823936,
0.00007110468141036108
] |
en
| 0.999998 |
To quantify the performance of the interrogation method, the integral delayed neutron counts for the three high enriched uranium materials placed inside the master AWCC were evaluated. Note that the contribution of background neutrons was subtracted using the data recorded in the reference AWCC detector (the details of the procedure are described in the Methods section). Because of shot-to-shot variations in neutron intensity, the integral delayed neutron counts were normalized to the neutron dose measured in the bubble chambers located on the target chamber exit flange, directly on the neutron-beam axis. Bubble chambers with three sensitivities were used to ensure proper measurement dynamic range in every shot (see Methods). The measured neutron doses for the laser-driven neutron pulses reported in this paper corresponded to 5–37 mrem. An overview of the measured results is provided in Table 1 . Note that some enriched uranium samples were interrogated with multiple neutron pulses to improve the statistical precision, and to monitor the reproducibility of the present test method. Table 1 shows results for all the individual short-pulse laser-driven neutron pulses where enriched uranium samples were present.
|
39753631_p31
|
39753631
|
Detection of nuclear material by active interrogation
| 4.120281 |
biomedical
|
Study
|
[
0.9985166192054749,
0.000335015298333019,
0.0011484757997095585
] |
[
0.9996508359909058,
0.0001325699413428083,
0.00017524015856906772,
0.00004134242408326827
] |
en
| 0.999997 |
Table 1 Summary of normalized integral delayed neutron (DN) counts over a 1–200 s interval for three 235 U enrichments studied in this work. AWCC mode 235 U enrichment (wt%) Neutron dose at 0° target chamber exit flange (mrem) Neutron dose uncertainty (mrem) Normalized integral of DN counts (counts/mrem) Uncertainty of normalized integral of DN counts (counts/mrem) Fast 12 14.6 0.5 32 10 Fast 38 19.0 0.6 103 9 Fast 66 13.2 0.6 103 12 Fast 66 21.9 0.4 132 8 Thermal 12 5.0 0.2 601 40 Thermal 12 18.3 0.6 785 27 Thermal 12 28.7 0.9 695 22 Thermal 12 23.6 0.6 782 20 Thermal 38 13.6 0.4 953 30 Thermal 38 34.5 1.2 1039 38 Thermal 38 21.9 0.6 1059 30 Thermal 38 33.3 0.9 963 27 Thermal 38 36.9 0.6 854 16 Thermal 38 27.2 0.2 878 11 Thermal 66 20.6 0.6 1090 33 Thermal 66 11.2 0.3 1151 38 Thermal 66 9.1 0.3 911 35 Thermal 66 27.6 0.2 1085 11 Thermal 66 36.7 0.6 908 17 Thermal 66 27.6 0.2 1041 10 Thermal 66 23.0 0.4 1292 24 Thermal 66 17.1 0.2 1068 19 Thermal 66 30.4 0.8 1173 31
|
39753631_p32
|
39753631
|
Detection of nuclear material by active interrogation
| 4.178032 |
biomedical
|
Study
|
[
0.9896470904350281,
0.0004108483262825757,
0.009942151606082916
] |
[
0.999022364616394,
0.0007309264619834721,
0.0002084290754282847,
0.000038342608604580164
] |
en
| 0.999998 |
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