Treadmill exercise promotes bone tissue recovery in rats subjected to high + Gz loads.

INTRODUCTION: High + Gz loads, the gravitational forces experienced by the body in hypergravity environments, can lead to bone loss in pilots and astronauts, posing significant health risks. MATERIALS AND METHODS: To explore the effect of treadmill exercise on bone tissue recovery, a study was conducted on 72 male Wistar rats. These rats were subjected to four weeks of varying levels of periodic high + Gz loads (1G, 8G, 20G) experiments, and were subsequently divided into the treadmill group and the control group. The treadmill group underwent a continuous two-week treadmill experiment, while the control group rested during this period. The mechanical properties, microstructure, and molecular markers of their tibial bone tissue were measured using three-point bending, micro-CT, and PCR. RESULTS: The results showed that treadmill exercise improved the elastic modulus, ultimate deflection, and ultimate load of rat bone tissue. It also increased the number, density, and volume fraction of bone trabeculae, and decreased their separation. Moreover, treadmill exercise enhanced osteogenesis and inhibited osteoclastogenesis. CONCLUSION: This study demonstrates that treadmill exercise can promote the recovery of bone tissue in rats subjected to high + Gz loads, providing a potential countermeasure for bone loss in pilots and astronauts.

Depth-dependent ratcheting strains of young and adult articular cartilages by experiments and predictions.

BACKGROUND: Ratcheting strain is produced due to the repeated accumulation of compressive strain in cartilage and may be a precursor to osteoarthritis. The aim of this study was to investigate the ratcheting behaviors of young and adult articular cartilages under cyclic compression by experiments and theoretical predictions. METHODS: A series of uniaxial cyclic compression tests were conducted for young and adult cartilage, and the effects of different loading conditions on their ratcheting behaviors were probed. A theoretical ratcheting model was constructed and applied to predict the ratcheting strains of young and adult cartilages with different loading conditions. RESULTS: Ratcheting strains of young and adult cartilages rapidly increased at the initial stage, followed by a slower increase in subsequent stages. The strain accumulation value and its rate for young cartilage were greater than them for adult cartilage. The ratcheting strains of the two groups of cartilage samples decreased with increasing stress rate, while they increased with increasing stress amplitude. As the stress amplitude increased, the gap between the ratcheting strains of young and adult cartilages increased gradually. The ratcheting strains of young and adult cartilages decreased along the cartilage depth from the surface to the deep layer. The ratcheting strains of different layers increased with the compressive cycle, and the difference among the three layers was noticeable. Additionally, the theoretical predictions agreed with the experimental data. CONCLUSIONS: Overall, the ratcheting behavior of articular cartilage is affected by the degree of articular cartilage maturation.

The toxicity thresholds of metal(loid)s to soil-dwelling springtail Folsomia candida-A review.

Increasing concentrations of metals in soil have posed a serious threat to the soil environment. The control and evaluation of soil metal hazards demand the establishment of soil ecological criteria, which is mainly based on the obtainment of toxicity thresholds. As the most typical representative of soil-dwelling springtails, Folsomia candida performs numerous essential ecological functions in soil and has been extensively used to investigate metal toxicity effects and thresholds. This review outlined the current state of knowledge on the metal toxicity thresholds to Folsomia candida, including (1) toxicity thresholds of soil metals for the different endpoints, (2) the influence factors of metal toxicity thresholds including the test conditions, the chemical forms of metal, the soil physicochemical properties, aging time and leaching, (3) the bioavailable fractions predicting metal toxicity thresholds, (4) the internal threshold of metals. To conclude, several recommendations for future research are given to obtain the more reliable toxicity thresholds and further supplement the toxicity data of metals to Folsomia candida.

The toxicity of exogenous arsenic to soil-dwelling springtail Folsomia candida in relation to soil properties and aging time.

Arsenic (As) is a toxic metalloid, but studies on As toxicity to soil-dwelling springtails are fairly limited, and did not consider the effects of various soil properties and long aging time. To address this, the toxicity of As to model organism-Folsomia candida were evaluated in the laboratory studies. The results showed that compared to the soils aged only for 15 d, the concentrations inhibiting 50% reproduction (EC50) significantly increased by 1.3- to 2.0-fold in four soils aged for 150 d, the concentrations causing 50% mortality (LC50) were higher than the highest test concentration in the most soils. Furthermore, the aging effects correlated significantly with soil free Fe oxides contents. The toxicity of As differed in ten soils aged for 150 d, the LC50 were 320-> 1280 mg/kg in acute test and the EC50 were 67-580 mg/kg in chronic test. Regression analysis indicated that soil clay was the most important single factor predicting soil As toxicity to reproduction, explaining 89% of the variance in EC50 values. Soil pH, free Fe oxides and Al oxides could also well explain the toxicity variance (> 65%), indicating that As sorption was a key factor controlling its toxicity.

The toxicity of exogenous nickel to soil-dwelling springtail Folsomia candida in relation to soil properties and aging time.

Nickel (Ni) is a toxic metal, but studies on Ni toxicity to soil-dwelling springtail are fairly limited, and did not consider the effects of various soil properties and long aging time. To address this, the chronic toxicity of Ni to model organism-Folsomia candida in relation to soil properties and aging time were evaluated in the laboratory study. The results showed that compared to the soils aged only for 7 d, the concentrations causing 50% mortality (LC50) and inhibiting 50% reproduction (EC50) basing measured total Ni in four soils aged for 120 d increased by 1.30-1.94 fold and 1.27-1.82 fold, respectively. Furthermore, the aging effects significantly correlated with soil pH. The toxicity values of Ni differed in ten soils aged for 120 d, the LC50 values were 279-4025 mg/kg and the EC50 values were 133-1148 mg/kg. When calculating the toxicity values basing water soluble and CaCl2 extracted Ni, the variations in LC50 values between ten soils decreased, while the variations in EC50 values increased. Regression analysis indicated that soil pH was the most important single factor predicting soil Ni toxicity to springtail, the combination of soil pH and OM could best explain Ni toxicity variance in ten soils (89.1% of the variance in LC50 values and 89.6% of the variance in EC50 values).

Inventories of heavy metal inputs and outputs to and from agricultural soils: A review.

Heavy metal pollution of agricultural soils is an important issue around the world. To understand the overall pollution process, accurate determination of every input and output pathway of heavy metals to and from soils is essential. Hence, input and output inventory, a quantitative analysis method of heavy metals balance in agricultural soils, has been widely used. However, due to differences in geography, climate, socioeconomic factors, industrial and agricultural production, substantial variation exists among existing input and output inventories for different countries and regions. In this study, we systematically analyzed these differences and the findings will improve the compilation of inventories worldwide.

High-accuracy optical coherence elastography digital volume correlation methods to measure depth regions with low correlation.

The decreasing correlation of optical coherence tomography (OCT) images with depth is an unavoidable problem for the depth measurement of the digital volume correlation (DVC) based optical coherence elastography (OCE) method. We propose an OCE-DVC method to characterize biological tissue deformation in deeper regions. The method proposes a strategy based on reliability layer guided displacement tracking to achieve the OCE-DVC method for the deformation measurement in deep regions of OCT images. Parallel computing solves the computational burden associated with the OCE-DVC method. The layer-by-layer adaptive data reading methods are used to guarantee the parallel computing of high-resolution OCT images. The proposed method shown in this study nearly doubles the depth of quantitative characterization of displacement and strain. At this depth, the standard deviation of displacement and strain measurements is reduced by nearly 78%. Under nonuniform deformation field, OCE-DVC method tracked the displacement with large strain gradient in depth region.

Dynamic changes and improvement paths of China's emergency logistics response capabilities under public emergencies-research based on the entropy weight TOPSIS method.

Introduction: Due to global industrialization and urbanization, natural disasters, accidents, and public health emergencies happen frequently. These events cause significant loss of life and property damage to countries worldwide. In the context of frequent public emergencies, enhancing emergency logistics response capabilities is crucial, ensuring rapid supply of rescue materials and support for rescue personnel, thereby saving lives and reducing economic losses. Methods: In order to identify the changes and enhancement paths of the emergency logistics response capability of Chinese regions under the shocks of public emergencies, this paper innovatively constructs emergency logistics response capability measurement indicators. This paper uses the entropy weight TOPSIS method and panel quantile regression model to quantify the change and enhancement paths of China's regional emergency logistics response capability under different events. Results: It is found that: (1) The gap in emergency logistics response capability among Chinese regions is widening, with the internal difference in the eastern region higher than that in the west, while the difference in the central region is relatively low. (2) China's emergency management department can effectively transform social logistics into emergency logistics, thereby promoting the improvement of emergency logistics response capabilities. (3) Sudden geological disasters break through the limits of social logistics resources when they cross lower scales, resulting in the failure of emergency logistics response capabilities. Discussion: This paper expands research on assessing emergency logistics capabilities, addressing issues in existing assessments such as reliance on single indicators and subjective measurement methods. Additionally, it quantifies the dynamic changes in China's regional emergency logistics response capabilities under public emergencies by extending the study of event content, types, and impacts. This enhances discussions on the effects of public emergencies. Finally, from an empirical perspective, the paper explores pathways to enhance regional emergency logistics response capabilities in China. In practice, this paper assists countries worldwide in assessing whether different regions of China can effectively provide emergency support for various resources in direct investments, thus providing a scientific basis for investment decisions.

Molecular level toxicity effects of As(V) on Folsomia candida: Integrated transcriptomics and metabolomics analyses.

Arsenic (As) is a widespread metalloid with well-known toxicity. To date, numerous studies have focused on individual level toxicity (e.g., growth and reproduction) of As to typical invertebrate springtails in soils, however, the molecular level toxicity and mechanism was poorly understood. Here, an integrated transcriptomics and metabolomics approach was used to reveal responses of Folsomia candida exposed to As(V) of 10 and 60 mg kg-1 at which the individual level endpoints were influenced. Transcriptomics identified 5349 and 4020 differentially expressed genes (DEGs) in low and high concentration groups, respectively, and the most DEGs were down-regulated. Enrichment analysis showed that low and high concentrations of As(V) significantly inhibited chromatin/chromosome-related biological processes (chromatin/chromosome organization, nucleosome assembly and organization, etc.) in springtails. At high concentration treatment, structural constituent of cuticle, chitin metabolic process and peptidase activity (serine-type peptidase activity, endopeptidase activity, etc.) were inhibited or disturbed. Moreover, the apoptosis pathway was significantly induced. Metabolomics analysis identified 271 differential changed metabolites (DCMs) in springtails exposed to high concentration of As. Steroid hormone biosynthesis was the most significantly affected pathway. Several DCMs that related to chitin metabolism could further support above transcriptomic results. These findings further extended the knowledge of As toxic mechanisms to soil fauna and offer important information for the environmental risk assessment.

Mechanical properties and biocompatibility characterization of 3D printed collagen type II/silk fibroin/hyaluronic acid scaffold.

Damage to articular cartilage is irreversible and its ability to heal is minimal. The development of articular cartilage in tissue engineering requires suitable biomaterials as scaffolds that provide a 3D natural microenvironment for the development and growth of articular cartilage. This study aims to investigate the applicability of a 3D printed CSH (collagen type II/silk fibroin/hyaluronic acid) scaffold for constructing cartilage tissue engineering. The results showed that the composite scaffold had a three-dimensional porous network structure with uniform pore sizes and good connectivity. The hydrophilicity of the composite scaffold was 1071.7 ± 131.6%, the porosity was 85.12 ± 1.6%, and the compressive elastic modulus was 36.54 ± 2.28 kPa. The creep and stress relaxation constitutive models were also established, which could well describe the visco-elastic mechanical behavior of the scaffold. The biocompatibility experiments showed that the CSH scaffold was very suitable for the adhesion and proliferation of chondrocytes. Under dynamic compressive loading conditions, it was able to promote cell adhesion and proliferation on the scaffold surface. The 3D printed CSH scaffold is expected to be ideal for promoting articular cartilage regeneration.

Effects of common artificial sweeteners at environmentally relevant concentrations on soil springtails and their gut microbiota.

Artificial sweeteners (AS) are extensively utilized as sugar substitutes and have been recognized as emerging environmental contaminants. While the effect of AS on aquatic organisms has garnered recent attention, their effects on soil invertebrates and gut microbial communities remain unclear. To address this knowledge gap, we exposed springtails (Folsomia candida) to both single and combined treatments of four typical AS (sucralose [SUC], saccharin [SAC], cyclamate [CYC], and acesulfame [ACE]) at environmentally relevant concentrations of 0.01, 0.1 and 1 mg kg-1 in soil. Following the first-generational exposure, the reproduction of juveniles showed a significant increase under all the AS treatments of 0.1 mg kg-1. The transcriptomic analysis revealed significant enrichment of several Kyoto Encyclopedia of Gene and Genome pathways (e.g., glycolysis/gluconeogenesis, pentose and glucuronate interconversions, amino sugar, and nucleotide sugar metabolism, ribosome, and lysosome) in springtails under all AS treatments. Analysis of gut bacterial microbiota indicated that three AS (SUC, CYC, and ACE) significantly decreased alpha diversity, and all AS treatments increased the abundance of the genus Achromobacter. After the sixth-generational exposure to CYC, weight increased, but reproduction was inhibited. The pathways that changed significantly (e.g., extracellular matrix-receptor interaction, amino sugar and nucleotide sugar metabolism, lysosome) were generally similar to those altered in first-generational exposure, but with opposite regulation directions. Furthermore, the effect on the alpha diversity of gut microbiota was contrary to that after first-generational exposure, and more noticeable disturbances in microbiota composition were observed. These findings underscore the ecological risk of AS in soils and improve our understanding of the toxicity effects of AS on living organisms.

[Optimization method of MOS sensor array for identification of traditional Chinese medicine based on electronic nose].

Optimization of sensor array is a significant topic in the application of electronic nose (EN). Stepwise discriminant analysis and cluster analysis combining with screening of typical index were employed to optimize the original array in the classification of 100 samples from 10 kinds of traditional Chinese medicine based on alpha-FOX3000 EN. And the identification ability was evaluated by three algorithm including principle component analysis, Fisher discriminant analysis and random forest. The results showed that the identification ability of EN was improved since not only the effective information was maintained but also the redundant one was eliminated by the optimized array. The optimized method was eventually established, it was accurate and efficient. And the optimized array was built up, that is, S1, S2, S5, S6, S8, S12.

Study on the removal of iron (II) and manganese (II) in acidic mine drainage by red mud: Performance and mechanism.

Red mud is an environmental burden during the alumina production process. To mitigate the hazards associated with red mud storage, this study investigated the utilization of alkaline red mud as a treatment agent for acidic mine drainage (AMD) with high concentrations of Fe(II) and Mn(II). This study explored the influence of reaction times, addition amounts of red mud, and pH values on the removal efficiency of Fe (II) and Mn(II) from high-concentration AMD. Various parameters such as suspended solids levels, effluent pH, and zeta potentials were measured to meet discharge standards. The adsorption mechanism of red mud was examined using SEM, XRD, EDX, XPS, and 3D-EEM analysis. Optimal conditions were determined as a reaction time of 2 h, pH value of 5.01 and the addition of 100 g/L red mud, achieving effective removal of Fe(II) (reduced from 1000 to 0.224 mg/L) and Mn (II) (reduced from 20 to 1.03 mg/L). The treated AMD meets discharge standards with reduced suspended matter content of 37.4 mg/L. These findings provided valuable insights for the utilization of red mud waste in engineering applications.

Loofah Sponge-Derived Hygroscopic Photothermal Absorber for All-Weather Atmospheric Water Harvesting.

The loofah gourd is like a natural water tank that stores underground water and drains it out after aging, leaving only a three-dimensional network consisting of hollow and interconnected fibers. This phenomenon inspired us to fabricate a solar-energy-powered sorption-based atmospheric water harvesting device using a loofah sponge. Herein, moisture absorption and photothermal conversion strategies are rationally designed to fast release the absorbed water. This is accomplished by filling the hollow and connected loofah fiber with LiCl and replacing the original luffa peel with a bacterial cellulose (BC)/carbon nanotube (CNT) photothermal conversion membrane. As a result, loofah/BC/CNT (LBC)@LiCl presents a high water absorption capacity of 2.65 g g-1 at 90% relative humidity (RH) and fast water release performance of 1.33 kg m-2 h-1 under 1.0 sun. Noticeably, ∼1.92-2.40 kg LBC@LiCl can produce daily drinking water for adults (2000-2500 mL) in one night outdoors at ∼66% RH, proving that it is a feasible method to overcome the drinking water shortage of poor and arid areas using cheap and renewable biomass material.

Liquid Metal-Tailored PEDOT:PSS for Noncontact Flexible Electronics with High Spatial Resolution.

Electric field-based noncontact flexible electronics (EF-NFEs) allow people to communicate with intelligent devices through noncontact human-machine interactions, but current EF-NFEs with limited detections (usually <20 cm) distance often lack a high spatial resolution. Here, we report a versatile material for preparing EF-NFE devices with a high spatial resolution to realize everyday human activity detection. Eutectic gallium-indium alloy (EGaIn) was introduced into poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) chains to fabricate this material, named Ga-PP. The introduction of EGaIn successfully regulates the intra- and interchain interactions of PEDOT chains and thus increases the π-electron accumulation on Ga-PP chains, which facilitates improvement of the electron storage of Ga-PP and its noncontact sensing ability. The water solubility of the obtained Ga-PP can reach approximately 15 mg/mL, comparable to that of commercial PEDOT:PSS, thus making Ga-PP suitable for various design strategies to prepare EF-NFE devices. We demonstrate that a conductive textile with a noncontact sensing ability can be achieved by immersing a commercial silk fabric into a Ga-PP solution for 5 min. With a detection distance exceeding 1 m, the prepared Ga-PP-based conductive textile (Ga-PP-CT) possesses outstanding noncontact sensing sensitivity, showing advantages in tracing the locations of signal sources and distinguishing motion states. Surprisingly, even when placed in water, Ga-PP-CT can be used to monitor the movement signals of athletes in different sporting events and output specific noncontact response signals for different sports. Intriguingly, the Ga-PP solution itself can be used to construct noncontact sensing conductive circuits, displaying the potential to be incorporated into smart electronics.

Study on molecular level toxicity of Sb(V) to soil springtails: using a combination of transcriptomics and metabolomics.

To date, numerous studies have focused on the toxicity of antimony (Sb) to soil-dwelling organisms at the individual level. However, little is known about Sb-caused molecular level toxicity. Here, an integrated transcriptomics and metabolomics approach was used to better reveal toxicity of Sb(V) to springtails Folsomia candida considering environmentally relevant speciation of Sb. No significant effects of Sb(V) on survival, reproduction and growth of springtails were observed using the ISO standard test. Transcriptomics analysis identified 1015 and 3367 differentially expressed genes (DEGs) after 2 and 7 d of exposure, indicating an increasing transcriptomal changes with time. Significantly enriched top GO (Gene Ontology) terms (chitin metabolic process, chitin binding and extracellular region) were shared between the two time exposure groups. However, no enriched KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway was shared, with fatty acid metabolism and apoptosis-fly being the most significant pathway, respectively. Metabolomics analysis identified 155 differential changed metabolites (DCMs) in springtails after 7 d of exposure. Antifolate resistance was the most significantly enriched pathway, in which dihydrofolic acid was up-regulated and three purine nucleotides (adenosine 5'-monophosphate, inosine 5'-monophosphate, guanosine 5'-monophosphate) were down-regulated. This indicated obvious repression of DNA replication, which was also observed by transcriptomics. Additionally, metabolites level related to chitin, oxidative stress, and protein metabolism significantly changed, and these metabolites could also support and confirm main transcriptomic results. Thus, the combination of multiomics facilitated better understanding of the molecular level of toxicity of Sb(V) in Collembola.

Effects of soil properties and long aging time on the toxicity of exogenous antimony to soil-dwelling springtail Folsomia candida.

The most existing studies on the toxicity of antimony (Sb) were performed in limited types of soil and after short aging time. Effects of soil properties and long aging time on chronic toxicity of Sb(III) and Sb(V) to model organism Folsomia candida were studied in the laboratory studies. The results showed that after the Sb(V)-treated soils were aged for 365 d, the Sb exhibited no toxicity to survival and reproduction even at the nominal highest concentration of 12,800 mg kg-1 in ten types of soils with distinct differences in soil properties. In the Sb(III)-treated ten soils aged only for 30 d, the concentrations causing 50% mortality (LC50) and concentrations inhibiting 50% reproduction (EC50) were 1288-3219 mg kg-1 and 683-1829 mg kg-1, respectively. The LC50 were higher than the highest test concentration and the EC50 significantly increased by 2.24-6.16 fold after the Sb(III)-treated soils were aged for 150 d, and soil pH was the most important single factor explaining the variance in aging effects. After the aging time was 365 d, similar with Sb(V)-treated soils, no toxicity were observed in the most Sb(III)-treated soils, indicating the increasing aging effects with aging time. Regression analysis indicated that the OM and pH were the most important single factor predicting Sb toxicity to reproduction in Sb(III)-treated soils aged for 30 and 150 d, respectively.

Ratcheting-fatigue behavior of trabecular bone under cyclic tensile-compressive loading.

This study aims to investigate the ratcheting-fatigue behaviors of trabecular bone under cyclic tension-compression, which are produced due to the accumulations of residual strain in trabecular bone. Simultaneously, the effects of different loading conditions on ratcheting behaviors of trabecular bone were probed. It is found that the gap between ratcheting strains under three stress amplitudes will gradually widen. As the stress amplitude increases, the ratcheting strain also increases. Mean stress has a significant effect on the ratcheting strain. When the mean stress is 0 MPa and 0.155 MPa, the ratcheting strain increases with the number of cycles. However, when the mean stress is -0.155 MPa, the ratcheting strain decreases as the cycle goes on. The existence of double stress peak holding time causes the creep deformation of trabecular bone, which leads to the increase of ratcheting strain. It is also noted that the ratcheting strain is greatly increased with prolongation of stress peak holding time. The digital image correlation (DIC) technique was applied to analyze the fatigue failure of trabecular bone under cyclic tension-compression. It is found that the increase of stress amplitude accelerates the damage of sample and further reduces its fatigue life. Cracks are observed in trabecular bone sample, and it is noted that the crack propagation is rapid during cyclic loading.

Influences of soil properties and long-time aging on phytotoxicity of antimony to barley root elongation.

Antimony (Sb) is a toxic element of global concern. To date, the most previous researches about phytotoxicity of Sb failed to fully consider the effects of soil properties and long-time aging. To address this, the toxicity of exogenous Sb(III) and Sb(V) were studied using the standardized barley root elongation bioassay. The results indicated that in ten soils aged only for 1 d, the EC10 (concentrations causing 10% inhibition) values were 221-3164 mg kg-1 and 135-4260 mg kg-1 in Sb(III)- and Sb(V)-treated soils, respectively. The EC50 values (concentrations causing 50% inhibition) were more than the setting highest concentration of 6400 mg kg-1 in half of ten soils. The regression analysis showed that the amorphous Fe oxide and pH were the most foremost single soil factor explaining above-mentioned variance in EC10, respectively, which suggested that the dominant soil factors were related to Sb forms. The inclusion of amorphous Mn oxide in above these two simple regression model could best explain the toxicity variance. After aged for 116 and 365 d, the phytotoxicity of Sb in Sb-treated soils significantly decreased and the phytotoxicity were even not found in the majority of Sb(V)-treated soils. The extent of aging varied with soils, and correlation analysis indicated that the aging effects negatively correlated with soil pH and positively correlated with clay and amorphous Al oxide in the Sb(III)-treated test soils.

Toxicity of exogenous hexavalent chromium to soil-dwelling springtail Folsomia candida in relation to soil properties and aging time.

Chromium (Cr) is a well-known toxic metal, but studies on Cr toxicity to soil-dwelling springtails are fairly limited, and did not consider the effects of various soil properties and long aging time. To address this, the chronic toxicity of Cr(VI) to survival and reproduction of model organism-Folsomia candida were evaluated in the laboratory studies. The results showed that compared to the soils aged only for 2 and 21 d, the concentrations inhibiting 50% reproduction (EC50) significantly increased by 2.8-5.2 fold and 1.7-2.6 fold, the concentrations causing 50% mortality (LC50) were higher than the highest test concentration in four soils aged for 150 d. Furthermore, the aging effects correlated significantly with soil amorphous Fe oxides. The EC50 values of Cr significantly differed in ten soils aged for 150 d, ranging from 27 to 512 mg kg-1, which were associated with the variations in reduction and sorption capacity in different soils. Regression analysis indicated that soil clay was the most important single factor predicting soil Cr toxicity to reproduction, and the inclusion of cation exchange capacity in the clay regression could best explain the toxicity variance (87.2%). Additionally, soil pH, organic matter and amorphous Fe oxides could also well explain the toxicity variance (>55%).