Adsorption Coefficient Research Articles

Two-dimensional type-II BlueP/GaN heterostructure for solar cells: A first-principles study

The geometric structure, electronic and optical properties, power conversion efficiency (PCE) of the BlueP/GaN heterostructure and its response to biaxial strain and electric field are systematically studied based on first-principles calculations. The results show that all configurations are found to be semiconductors with indirect band gaps of 1.34, 1.79, 1.20 and 1.40 eV, respectively. The BlueP/GaN heterostructure possesses excellent carrier mobility. The electron mobility of AA' configuration is up to 3.329 m2 V−1 s−1, while the hole mobility can reach 1.707 m2 V−1 s−1. The visible light absorption intensity of the BlueP/GaN heterostructure can significantly improve compared with the corresponding monolayers. The maximum adsorption coefficient of AA configuration can attain to 1.01 × 105 cm−1 at the 422 nm visible light. Especially, the tunable band gap and type-II band alignment are achieved through biaxial strains and external electric fields. The BlueP/GaN heterostructure can achieve 24.13 % PCE at 4 % tension strain. External electric fields can more accurately modulate the band gap to dynamically control electronic properties of BlueP/GaN heterostructure. Hence, the results not only provide theoretical basis for sustainable energy application of BlueP/GaN heterostructure, but also provide motivation to experimentally explore BlueP/GaN heterostructure for harvesting green, abundant and clean solar energy.

Can Microplastics Accumulate Toxic dye in Water? An adsorption-desorption Study under Different Experimental Conditions.

The adsorption/desorption of Rhodamine B (RhB) on Polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC) microplastics (MPs) was investigated in this study. The results showed that RhB adsorption on the selected MPs was fast. The adsorption coefficients (Kd) of RhB were 2036 ± 129, 1557 ± 91, and 63 ± 8.5L kg- 1 for PS, PP, and PVC, respectively. RhB adsorption on PS and PP increased with increasing temperature and decreasing ionic strength, whereas RhB adsorption on PVC showed a completely opposite trend. The binding strength of RhB on the three types of MPs was weak as demonstrated by the high total desorption percentage, which ranged from 79.59 ~ 89.39%. This study shows that PP and PS MPs can accumulate RhB in the aquatic environment and their potential combined toxic risks should be taken seriously.

Adsorption isotherm model of Hg2+ with biochar from young coconut waste

Biochar is a carbon-rich byproduct of biomass pyrolysis that may be used to restrict Hg mobility in soil by utilizing amelioration technology. This study examines the ability of biochar from young coconut waste to adsorb Hg in solution. Isothermal adsorption of Hg by batch equilibrium method. The basic principle of Hg adsorption behavior with biochar from young coconut waste (B-YCW) processed through the Kon-Tiki method at a temperature of 682 0C, moisture of 81.27%, and a yield ratio of 20.87% at a size of 0.5 mm. The adsorption of Hg2+ on B-YCW increased with increasing Hg concentration and decreasing pH. The capacity and adsorption coefficient of Hg2+ by biochar from young coconut waste was 312.88 mg g−1 and 69.64 L Kg−1 at a pH of 1.55 and a concentration of 100 mg L−1 Hg2+. The adsorption isotherm of Hg2+ occurs in the Freundlich and Langmuir models (Freundlich > Langmuir). The Freundlich model (y = 1.0375x - 1.2523; R² = 1) with a value of n of 0.96 and KF of 17.78 (L mg−1)1/n, and the Langmuir II model (y = 17.126x - 0.0244; R² = 1), with average Qm was 18.57 mg g−1; KL 68.198 L mg−1 and RL 0.0054 (favorable) from the Langmuir isotherm model.

Synthesis and Properties of Ag‐Au Alloy Nanoparticles with Controlled Composition for Computed Tomography Imaging Applications

AbstractNumerous non‐invasive assays have been developed to support CT imaging, consequently increasing the precision of diagnosis. Although these efforts made a significant contribution to clinical research, there is still more to be done. The goal is to replace conventional contrast agents with more potent ones. In this study, Ag−Au alloy nanoparticles were fabricated by substitution method between the precursor Au3+ and the previously prepared Ag nanoparticles. Effects of Au3+ quantity on the formation and characteristics of Ag−Au alloy nanoparticles were investigated. It showed that Ag−Au nanoalloy with a size of 14.2±1.0 nm, SPR absorption peak at 520 nm, and Ag: Au atomic ratio of approximately 3 : 1 were appropriate for biomedical applications. After phase transfer using poly (maleic anhydride‐alt‐1‐octadecene) (PMAO), the nano Ag−Au solution owned remarkable durability, stability and non‐toxicity Vero healthy cell line at high test concentration. In‐vitro CT imaging demonstrated a good X‐ray adsorption coefficient, and the hounsfield units (HU) was noticeably increased. As a promising CT contrast agent, the X‐ray attenuation of nano Ag−Au solutions correlated linearly with concentrations. These findings led to a potential application in the biomedical field, particularly in computed tomography (CT) imaging diagnosis.

Degradation and sorption of the herbicide pelargonic acid in subsoils below railway tracks compared to a range of topsoils

BackgroundPelargonic acid is a non-selective herbicide derived from natural sources with a range of potential applications in areas where synthetic herbicides may be less acceptable. One such use area is weed control on railway tracks. To assess the potential leaching of pelargonic acid to groundwater for this specific use, we conducted degradation and sorption studies with soils from railway tracks and, for comparison, with a range of topsoils.ResultsDegradation of pelargonic acid was very rapid in subsoils from railway tracks with half-lives (DT50) of < 1 day (geom. mean DT50, 5.8 h), and even faster in the selected agricultural topsoils (1.5 h). The starting concentration had a strong influence with much slower degradation at higher spike levels. Adsorption to the railway soils (alkaline soils with low organic matter content) was expectedly weak (Freundlich adsorption coefficients KF of 0.06–0.31 mL/g) and clearly stronger in the topsoils (0.2–40 mL/g). Organic carbon normalized adsorption coefficients (KFoc) ranged from 11 to 371 mL/g (all soils) and were pH dependent, consistent with the behaviour of weak acids. Computer modelling using the software PELMO and a set of scenarios for herbicide use on railway tracks developed for the authorisation in Germany yielded predicted environmental concentrations in groundwater of < 0.001 µg/L when parameterised with the adsorption and degradation endpoints from subsoils.ConclusionsThe leaching potential of pelargonic acid may be considered low even in application scenarios with sandy soils with low organic matter content such as those found below railway tracks.

Ammonium Adsorption by Surface Sediments in the Loughor Estuary, UK

In this study, adsorption isotherm experiments were used to study ammonium adsorption by surface bed sediments in the Loughor Estuary, South Wales. The findings indicated that the adsorption isotherm was linear and fitted the Freundlich adsorption isotherm, K*. The adsorption coefficient of ammonium in the study area ranged from 9.3 to 18 ml/g and the dimensionless ammonium adsorption coefficient was found to be ranged between 23.0 and 36.5. These values correlated well with the organic carbon content, of the sediments and can be considered as the main factors controlling ammonium sorption. The results also showed that salinity affected the adsorption of ammonium and the distribution of ammonium between the sediments and the water column. The amount of ammonium adsorption on the sediments was found to decrease gradually with the increment of the salinity levels.

Sorption of four antibiotics onto pristine biochar derived from macadamia nutshell

In this study, the sorption properties of ciprofloxacin, ofloxacin, sulfamethoxazole, and trimethoprim on biochar derived from macadamia nut shells were investigated. The raw biomass was pyrolyzed at 600 °C to create a highly porous material with a surface area of 392 m2 g−1. The produced biochar was found to be a valuable material for both environmental remediation and carbon sequestration due to its high carbon and oxygen content. The sorption properties of four antibiotics on the produced biochar were compared using Bayesian nonlinear regression based on second-order kinetics and the Langmuir model. The Bayesian estimation successfully compared the adsorption coefficients of the antibiotics, which can be directly visualized through graphical grammar using the probability density distribution. The results demonstrated the ability of macadamia nut shell biochar to remove antibiotics from water at neutral pH, and this material has the potential to be used for treating other emerging contaminants.

Gas transport mechanisms through MOF glass membranes

The study provides an in-depth study on the gas adsorption and transport behaviors of MOF glass membranes for the first time. Temperature dependance of gas permeability, adsorption coefficients and diffusion coefficients between 298 ​K and 313 ​K for TIF-4 and ZIF-62 glass membrane were evaluated. The CO2 permeability was dominated by the adsorption process, while CH4 transport was mainly driven by the activated diffusion. Further, the MOF glass membranes exhibited significant entropic selectivity in adsorption, along with notable enthalpic selectivity in diffusion.

Highly Robust, Compressible, Anisotropic, and Fire-Retardant Polyimide/Hydroxyapatite Nanowires/Reduced Graphene Oxide Aerogel for Rapid Adsorption of Viscous Oil Assisted by Sunlight.

Improving the adsorption efficiency of porous adsorbent materials for organic liquids with high viscosity is crucial for addressing oil spill incidents. In this study, a high-performance aerogel adsorbent composed of polyimide (PI), hydroxyapatite nanowires (HAPnws), and reduced graphene oxide (rGO) has been fabricated, which leverages reduced flow tortuosity through anisotropic structures and solar-assisted viscosity reduction via photothermal materials. The prepared anisotropic PI/HAP/rGO aerogel, with directional channels, shows unique mechanical properties with high stiffness along the axial direction and compressibility along the radial direction. PI/HAP/rGO, featuring vertically aligned channels, demonstrated superior adsorption efficiency (the adsorption coefficient K s reached 0.37 kg m-1 s-1/2 for an engine oil with a viscosity of ~144 mPa·s) for oil of varying viscosities compared to similar aerogels with uniform pores, because of the substantially reduced flow tortuosity. The photothermal properties of rGO further enhance the adsorption speed of PI/HAP/rGO for viscous oil under sunlight, including crude oil with ultrahigh viscosity. In addition, PI/HAP/rGO exhibits excellent fire resistance, allowing for reusability via both adsorption-compression and adsorption-combustion cycles. The robust and compressible PI/HAP/rGO aerogels with high adsorption efficiency for viscous oil and fire resistance represent an ideal solution for practical oil spill treatment, and this approach also offers inspiration for the development of advanced adsorbent materials.

A study on the Si1-xGex gradual buffer layer of III-V/Si multi-junction solar cells based on first-principles calculations.

III-V/Si multi-junction solar cells have been widely studied in recent years due to their excellent theoretical efficiency (∼42%). In order to solve the problem of lattice mismatch between Si and III-V compounds of III-V/Si solar cells, different hexagonal Si1-xGex buffer layer models on the surface of hexagonal diamond Si(001) were built, and the structural, electronic and optical properties of the proposed models were calculated based on first principles calculations. The results showed that all models of the designed buffer layer could effectively reduce the lattice mismatch, and the buffer layer hex-Si1-xGex (x = 0, 0.75, and 1) is the ideal model and has achieved the best lattice-matching improvement with high defect formation energy, as well as direct band gap properties and a larger light adsorption coefficient. These theoretical models, with their analyzed properties, could offer a promising pathway toward realizing high efficiency and low cost III-V/Si multi-junction solar cells.

DESALINATION OF SYRDARYA WATER BY POLYAMIDE (PA) MEMBRANES

South Kazakhstan water is an important source of drinking water in an increasingly scarce world. An adequate integrated assessment of water quality from the point of view of its suitability for human use therefore remains a pressing issue. The purpose of this work is to assess water quality using nano-filtration methods, using the example of the South Kazakhstan is- Syrdarya River, and their suitability for use by the population. The main advantage of nano-filtration methods is the production of better-quality water without harmful bacteriological and microbial contamination. Determination of the water permeability index, sodium, magnesium adsorption coefficients, microelement content, cation, and anionic composition. The results showed that the main pollutants of the Syrdarya River in the studied region were sulfates, nitrites, copper, and magnesium. Sulfate content 548 mg/l (5.5 MPC), nitrite 0.028 mg/l (1.4 MPC), copper 0.003 mg/l (3.0 MPC) and magnesium 71.5 mg/l (1.8 MPC). The results of the after purification of in a membrane apparatus in the absence of toxic substances of the third and fourth hazard classes, as well as odor and taste, points no more than 1-2, the biological demand for oxygen is reduced by 92, 5%, and the chemical oxygen demand is reduced by 100%. The results of water purification of the Syrdarya rivers in a membrane apparatus in percentages: nitrites 84%, nitrate 15%, sulfates 84%, mineralization 95%, and the odor and taste index is zero, which meets sanitary and hygienic requirements and is suitable for sustainable use as drinking water in the South Kazakhstan region. The system guarantees the removal of up to 99% or higher of inorganic salts, up to 99.5% of organic substances, and 100% removal of bacteria and viruses.

Effect of Mixed Manure and Inorganic Fertilizer on Phosphorus Adsorption and Desorption Characteristics of Vertisols in Haramaya District, Eastern Ethiopia.

Applying inorganic phosphorus fertilizer is less effective in increasing crop yields in tropical soils due to precipitation and adsorption reactions. However, research suggests that partial substitution of organic and inorganic fertilizers has shown to improve the efficiency of applied phosphorus fertilizer by reducing its adsorption and enhancing desorption due to their synergistic effects. This study aimed to investigate the impact of treating the soil with mixed manure (MM) rates and blended nitrogen, phosphorus, sulfur, and boron (NPSB) fertilizer on the soil's phosphorus adsorption and desorption characteristics. Results showed increased adsorbed phosphorus in all treatments, with increased added phosphorus (P) concentration from 100 to 500 mg kg-1. However, the efficiency of adsorbed P decreased significantly as added P concentration rates increased from 100 to 400 mg·kg-1 in all treatments and then decreased as the added P concentration advanced to 500 mg·kg-1. Moreover, in all treatments that received combined applications of MM and blended NPSB, both quantity and percentage of desorbed P showed a significant increase. The Freundlich adsorption coefficient and constant were also significantly reduced because of the combined application of MM and blended NPSB, compared to the control and their sole applications. Overall, the soil treated with a combined application of 15 t·ha-1 of MM with 100 kg·ha-1 of blended NPSB showed the highest reduction in the efficiency of adsorbed P, percentage of desorbed P, Freundlich adsorption capacity, and intensity by 8%, 37.5%, 60%, and 58%, respectively, as compared to the control. These findings indicate that the combined application of MM and blended NPSB can improve the P availability and uptake by maize by reducing its adsorption while increasing desorption characteristics. Finally, this experiment recommends further research on the long-term effects of MM and blended NPSB on P adsorption and desorption characteristics of vertisols.

Site-scale groundwater pollution risk assessment using surrogate models and statistical analysis

Petroleum pollution in soil and groundwater has emerged as a significant environmental concern worldwide. As a sustainable and cost-effective in-situ remediation technique, Monitored Natural Attenuation (MNA) exhibits significant promise in addressing sites contaminated by petrochemicals. This study specifically targets a typical petrochemical-contaminated site in northern China and employs GMS software to establish a comprehensive physical model. The model relies on time-series monitoring data of phenol concentrations spanning from 2018 to 2020, effectively simulating both the leakage and natural attenuation of phenol. Within this study, the adsorption coefficient and maximum adsorption capacity emerge as the foremost influential factors shaping the outcomes of the model. Given the inherent heterogeneity of the site and the variability of hydrochemical conditions, parameters such as dispersion, porosity, and adsorption coefficient exhibit significant uncertainties. Consequently, relying on traditional deterministic models to predict the feasibility of MNA technology is not reliable. Therefore, this study employs machine learning (ML) methods to construct stochastic parameter models based on physical processes. The Random Forest Regression (RFR) algorithm, after trained, demonstrates strong alignment with numerical model output, exhibiting an average Nash-Sutcliffe Efficiency (NSE) >0.96. Using a stochastic approach, RFR iteratively computes phenol concentration across 6000 sets of parameters. Applying probability statistics, the model shows a notable reduction in the likelihood of phenol concentrations exceeding a threshold, dropping from 64.0% to 15.7% before and after natural attenuation. In parameter uncertainty, the stochastic model emphasizes natural attenuation's efficacy in mitigating phenol pollution risk (porosity being the most influential factor). This case study proposed a novel method to quickly assess the pollution risks at petrochemical sites under the influence of the uncertainty of pollutant transport and reaction parameters. The results can provide a reference for the pollution risk assessment at petrochemical sites, especially in sites with high stratigraphic heterogeneity or insufficient transport parameter data.

Predictive modeling for VOC adsorption on TiO2 filters: Implications for enhanced photocatalytic oxidation in indoor air quality management

Adsorption of volatile organic compounds (VOCs) onto the surface of a TiO2 filter is essential for initiating photocatalytic oxidation (PCO). This study investigated the adsorption coefficients (K) of 14 VOCs under different relative humidities (RH) and explored the influence of different air velocities on the adsorption of Methyl isobutyl ketone (MIBK). Consequently, a polyparameter linear free energy relationship (pp-LFER) model was established to predict lnK at 35 % RH (lnK35%). Moreover, the study found that lnK has a linear relationship with RH, represented as lnK=αRH+β. The parameters ′α′ and ′β′ can be accurately predicted using the Henry’s Law constant (K°OH) and lnK35%, respectively. By combining the pp-LFER model with regression equations for ′α′ and ′β′, it is possible to predict lnK for VOCs across various RH levels. The study also revealed that the adsorption coefficient of increases with escalating air velocities (0.04 – 0.34 m/s), primarily due to mass transfer. The observed low adsorption performance for aldehydes, commonly seen as by-products in the PCO process, suggests cautious usage of the PCO filtration system in practice before the by-products are eliminated downstream. This study offers valuable insights for the practical application of PCO technologies in the comprehensive removal of indoor VOCs.

Characterization and application of lamellar zeolite‐X prepared from kaolin

AbstractA simple and effective method was reported for the rapid synthesis of zeolite X from kaolin by adding a template agent. The results of X‐ray diffraction confirm the good crystallinity of the synthesized X‐zeolite with lamellar structure. Transmission electron microscopy images clearly demonstrate the lamellar structure of the synthesized X‐zeolite. The corresponding selective electron diffraction pattern suggests that the crystal structure of X‐type zeolite is octahedral. The co‐existence and uniform distribution of Si, Al, O, and Na in the layered structure of the synthesized X‐type zeolite are detected by element mapping. In addition, N2 adsorption–desorption measurement indicates that the specific surface area of the lamellar zeolite X is 153.4625 m2 g−1. The micropore surface area is 148.8374 m2 g−1, and the micropore volume is 0.073377 m2 g−1. After exploring the influence of different temperatures on the adsorption of carbon dioxide, the research shows that two‐dimensional zeolite X has the best adsorption capacity for carbon dioxide. The adsorption and separation performance of CO2/CH4 was investigated. The study showed that the adsorption and separation coefficient of two‐dimensional zeolite X was the highest.

Моделирование как прогноз трансформации почв при техногенном засолении

The problem of soil salinization is relevant not only for agricultural areas but also for mining, where brines enter the surface as formation water or runoff from sludge storage facilities and salt dumps of mining enterprises. Currently, there is little elaboration of assessment and lack of normative support (MPC, APC) for assessment of technogenic salinisation of soils. The aim of this research is to develop a mathematical model for predicting the transformation of soils affected by technogenic salinization. The research focuses on soils in three types of landscapes, namely eluvial, transitional, and alluvial, located in the area of technogenic salinization. To develop the model, information-logical analysis and soil indicators were employed. These indicators were determined by standard methods. According to the information-logical analysis the sodium adsorption coefficient is the dominant factor of soils’ salinity; descending further: calcium ion content, sulfates content in the soil water extract and the calculated indicators (∆pH and pH) of the salt extract. The model showed that the highest amount of toxic salts is observed when pHKCl ranges from 5.3 to 7.4, sulfate content is above 500 mg/kg, calcium content is above 1000 mg/kg, SAR is above 10, and ∆pH is below 0.5. These indicator values correspond to alluvial soils found in small river valleys; these soils are highly prone to transformation. Using the obtained information-logical model and soil indicators, it is possible to make a forecast of soil transformation under technogenic salinization.

Poly(arylene ether nitrile) composite foams with magnetically and electrically separated structures for frequency-selective electromagnetic interference shielding

With the rapid development of communication technology and modern intelligent electronic systems, the demand for frequency-selective electromagnetic interference (EMI) shielding materials has grown. In this work, poly(arylene ether nitrile) (PEN) composite foams with separated magnetic and conductive layers were prepared via delayed non-solvent induced phase separation, where the distribution of magnetic and conductive layers was designed to construct double-layer asymmetric structures and sandwich structures. Benefiting from destructive interference between electromagnetic waves (EMWs) in the magnetically and electrically separated porous structures, the double-layer asymmetric composites (M−C) exhibited outstanding absorption-dominated EMI shielding performance with favorable frequency selectivity, which did not occur in conventional double-layer composites. Specifically, M−C achieved a maximum shielding efficiency (SE) of 49.3 dB and a maximum average absorption ratio (Ar) of 93.9 %. Meanwhile, increasing the thickness of the magnetic layer of M−C can lower the characteristic frequency (fc) of the shielding peak and enhance average SE and average Ar. Moreover, M−C could show higher fc, average Ar, and average adsorption coefficient in the X-band when the incident EMWs first met with the magnetic layer, which was unavailable in frequency-selective PEN-based sandwich-structured composites. This effort offers a novel, flexible design to fabricate absorption-dominated EMI shielding materials with frequency selectivity.

Modeling 4.3 billion years of water history on Phobos

Phobos, one of the Martian moonlets, has been the focus of long-standing scientific investigation, particularly regarding its origin: whether it was formed by a giant impact or a captured asteroid. In this study, we investigate the long-term internal evolution of Phobos over 4.3 billion years using a 3-dimensional thermal diffusion and water transport model, named ASTRA. The model newly implements reflected visible light and infrared radiation from Mars, orbital evolution of Phobos, water vapor adsorption on rock grain surfaces, and suppressed permeability due to the surface dust layer in addition to the previous study, allowing us to simulate different grain sizes of 1, 10, 100, and 1000 μm, adsorption coefficients of 1 and 10 kg m−3, and initial water contents of 0.1, 1 or 10 wt%.Our simulation results revealed that without the water vapor adsorption effect, the water inside Phobos would be lost over several billion years for an initial water content of 0.1 wt%. However, when water vapor adsorption was considered, scenarios emerge in which Phobos could retain water to the present day. In the case of a grain size of around 100 μm, Phobos could still continuously release water flux of 10−4–10−3 g s−1 for an initial water content of 0.1 wt%, and 10−2–1 g s−1 for an initial water content of >1 wt%. Furthermore, our research shows the possibility of subsurface condensed water ice in deep high latitude regions and the formation of a gas torus by escaping water-related molecules. If the future MMX mission can measure the water-related ions near the gas torus of Phobos with much >104 cm−2 s−1, the origin of Phobos is most likely the captured asteroid with an initial water content of >1%. For further detailed analysis, our results emphasize the importance of exploring surface soil parameters through soil sample return by the MMX mission.

TiO2-doped bilirubin-imprinted polydopamine cored with Fe3O4 nanoparticle for bilirubin selective adsorptivity enhancement

As one of the essential treatments for bilirubin removal in clinical, hemoperfusion of bio-sorbents required efficacy, efficiency and biosafety. Dopamine of biocompatibility and spontaneous polymerization was herein proposed for the bilirubin-imprinted adsorptive polymers of selectivity, doped with TiO2 of adsorptivity and Fe3O4 as fixed magnets. Via electrostatic reaction and hydrogen bonding, the magnetic sorbents composed of polydopamine doped with TiO2 removed bilirubin of 263.5 mg·g−1 non-homogeneously during 240 min. With a competitive adsorption coefficient (tN) of 10.4, the magnetic sorbents also exhibited the decent blood compatibility of acceptable hemolysis ratio and plasma recalcification time. Prospectively, the TiO2-doped bilirubin-imprinted PDA cored with Fe3O4 was potentially for bilirubin selective removal via hemoperfusion in clinic.

A simulation model (PostPLANT-Soil) for predicting pesticide concentrations in succeeding leafy vegetables: I. Validation with experimental data in a Japanese Andosol field.

We developed a simulation model for predicting pesticide concentrations in succeeding leafy vegetables (PostPLANT-Soil), which includes the process of pesticide uptake from plant roots. To validate the model, we compared pesticide concentrations simulated by the model with values measured from field experiments in an upland Andosol. The model validation showed that pesticide concentrations in the plant shoot were correlated with the concentrations in the soil solution rather than those of the water-extracted pesticides. The model successfully simulated the concentration changes in plant shoots when the simulated concentrations of the pesticides in the soil solution were fitted to the measured values by considering the key parameter - the corrective coefficient for the soil adsorption coefficient. However, the simulated shoot concentrations at the appropriate harvest period exceeded the measured values. This indicates that the leafy vegetable used in this study may have some metabolic capacity for the pesticides.