Optimizing the preparation of paraffin sections from stallion testes.

The preparation of paraffin sections is an important experimental technique in animal histological research, and key factors that determine the quality of a section include the dehydration time, waxing time, and drying temperature of the paraffin section. Paraffin sections obtained from testis tissue of adult horses exhibited higher quality with clear tissue structure and complete cell morphology after they underwent gradient dehydration for 6 hours, were immersed in wax for 60 minutes, and were dried in a 75-degree oven for 15 minutes. The detailed, optimized procedures that are developed in the current study may simplify histological experiments and research on equine testes.

Linking stigma to social isolation among colorectal cancer survivors with permanent stomas: the chain mediating roles of stoma acceptance and valuable actions.

PURPOSE: Colorectal cancer (CRC) survivors with permanent stomas might be at higher risk of social isolation, and stigma can play an important role in the development of social isolation. However, the underlying psychological mechanisms are understudied. The current study examined how stoma acceptance and valuable actions mediated the relationships between stigma and social isolation among CRC survivors with permanent stomas. METHODS: A cross-sectional survey was conducted with a sample of 303 CRC survivors with permanent stomas. The chain mediation models were conducted using the PROCESS macro for SPSS to explore the pathways through which stigma can be associated with CRC survivors' social isolation, mediated by stoma acceptance and valuable actions. RESULTS: The results indicated that higher stigma was related to lower stoma acceptance, less personal values enactment, and higher social isolation, as well as lower objective social connectedness and subjective social belongingness among CRC survivors with permanent stomas. Additionally, the mediational analyses revealed that stoma acceptance and valuable actions jointly mediated the relationships between stigma and social isolation. CONCLUSION: Social isolation among CRC survivors during the adjustment to both stoma and stigma may be alleviated through tailored interventions that improve stoma acceptance and valuable actions. IMPLICATIONS FOR CANCER SURVIVORS: The chain mediating roles of stoma acceptance and valuable actions highlight that tailored interventions, such as acceptance and commitment therapy, can be targeted for this population, considering this population's unique needs.

Different expression patterns of DNA methyltransferases during horse testis development.

DNA methyltransferases (DNMTs) are important epigenetic modification during spermatogenesis. To further evaluate the pattern of DNMTs in horse testes during development, we investigated the expression and localization of DNMT1, DNMT3a and DNMT3b at different time points. The qRT-PCR results showed that DNMT1 expression was maintained in testes tissue from 6-month-old (0.5y) to 2-year-old (2y) of age and decreased after 3-year-old (3y) (P < 0.01). The expression levels of DNMT3a and DNMT3b peaked in testes tissue at 3y (P < 0.01). At 4-year-old (4y), the expression of DNMT3a and DNMT3b was decreased and became similar to that at 0.5y. Immunofluorescence of DNMT1, DNMT3a and DNMT3b on testis samples confirmed the differential expression and localization of these three DNA methylation transferases during horse development. Further molecular biological studies are needed to understand the implications of the expression patterns of these DNMTs in horse testes.

Low-Frequency Evolution Mechanism of Customized HEAs-Based Electromagnetic Response Modes Manipulated by Carbothermal Shock.

An emerging carbothermal shock method is an ultra-convenient strategy for synthesizing high-entropy alloys (HEAs), in which the intelligent combination of carbon support and HEAs can be serve as a decisive factor for interpreting the trade-off relationship between conductive gene and dielectric gene. However, the feedback mechanism of HEAs ordering degree on electromagnetic (EM) response in 2-18 GHz has not been comprehensively demystified. Herein, while lignin-based carbon fiber paper (L-CFP) as carbon support, L-CFP/FeCoNiCuZn-X with is prepared by carbothermal shock method. The reflection loss of -82.6 dB with thickness of 1.31 mm is achieved by means of pointing electron enrichment within L-CFP/FeCoNiCuZn HEAs heterointerfaces verified by theoretical calculations. Simultaneously, low-frequency evolution with high-intensity and broadband EM response relies on a "sacrificing" strategy achieved by construction of polymorphic L-CFP/semi-disordered-HEAs heterointerfaces. The practicality of L-CFP/FeCoNiCuZn-X in complex environments is given prominence to thermal conductivity, hydrophobicity, and electrocatalytic property. This work is of great significance for insightful mechanism analysis of HEAs in the application of electromagnetic wave absorption.

Highly efficient Cu(II) capture by salicylaldoxime functionalized magnetic polydopamine core-shell hybrids: Behavior and mechanism.

Functionalized magnetic nanocomposites were considered as promising adsorbents owing to their abundant functional groups and ease of separation properties. Herein, we combined the solvothermal method with molecular copolymerization to synthesize a salicylaldoxime-grafted magnetic polydopamine (SMP) core-shell hybrid and exploited it for Cu(II) adsorption. The physicochemical properties of SMP were comprehensively studied by SEM, TEM, XRD, FT-IR, TGA, XPS, and VSM measurements. The results manifested that polydopamine acts as a bridge connecting magnetic iron oxide and salicylaldoxime to fabricated core-shell hybrids with rich functional groups. The batch experimental results showed that the Cu(II) adsorption was consumingly pH-reliant behavior, while adsorption data fitted the pseudo-second-order kinetic model and Langmuir isothermal model well, and the adsorption process achieved equilibrium within 60 min. Moreover, SMP exhibited remarkable anti-interference and can be recycled for 5 times with an inconspicuous decrease in adsorption performance. Importantly, salicylaldoxime functionalization endowed SMP with maximum Cu(II) adsorption capacity of 141.24 mg/g at pH 6.0 and 25 °C as compared with pure MP. Based on FT-IR and XPS study, the main adsorption mechanisms were proposed with a synergistic effect including a strong chemical chelation and partial Cu(II) reduction. Importantly, this strategy can be extended to multifunctional magnetic composites for Cu-contaminated wastewater cleanup.

Differences in toxicity induced by the various polymer types of nanoplastics on HepG2 cells.

The problem of microplastics (MPs) contamination in food has gradually come to the fore. MPs can be transmitted through the food chain and accumulate within various organisms, ultimately posing a threat to human health. The concentration of nanoplastics (NPs) exposed to humans may be higher than that of MPs. For the first time, we studied the differences in toxicity, and potential toxic effects of different polymer types of NPs, namely, polyethylene terephthalate (PET), polyvinyl chloride (PVC), and polystyrene (PS) on HepG2 cells. In this study, PET-NPs, PVC-NPs, and PS-NPs, which had similar particle size, surface charge, and shape, were prepared using nanoprecipitation and emulsion polymerization. The results of the CCK-8 assay showed that the PET-NPs and PVC-NPs induced a decrease in cell viability in a concentration-dependent manner, and their lowest concentrations causing significant cytotoxicity were 100 and 150 µg/mL, respectively. Moreover, the major cytotoxic effects of PET-NPs and PVC-NPs at high concentrations may be to induce an increase in intracellular ROS, which in turn induces cellular damage and other toxic effects. Notably, our study suggested that PET-NPs and PVC-NPs may induce apoptosis in HepG2 cells through the mitochondrial apoptotic pathway. However, no relevant cytotoxicity, oxidative damage, and apoptotic toxic effects were detected in HepG2 cells with exposure to PS-NPs. Furthermore, the analysis of transcriptomics data suggested that PET-NPs and PVC-NPs could significantly inhibit the expression of DNA repair-related genes in the p53 signaling pathway. Compared to PS-NPs, the expression levels of lipid metabolism-related genes were down-regulated to a greater extent by PET-NPs and PVC-NPs. In conclusion, PET-NPs and PVC-NPs were able to induce higher cytotoxic effects than PS-NPs, in which the density and chemical structure of NPs of different polymer types may be the key factors causing the differences in toxicity.

Effects of Astaxanthin Supplementation on Fatigue, Motor Function and Cognition: A Meta-Analysis of Randomized Controlled Trials.

Dietary astaxanthin supplementation has been demonstrated to have many beneficial and health-promoting effects. The purpose of this systematic review and meta-analysis was to assess the effect of astaxanthin supplementation on fatigue, cognition, and exercise efficiency. A total of 11 randomized controlled trials (RCTs) with 346 healthy participants were included. The random effects model and pooled standardized mean difference (SMDs) were used according to Hedge's g for the meta-analysis, and a meta-regression was also conducted. The results of the two existing studies showed a positive trend for astaxanthin in subjective fatigue relief. The effects of astaxanthin supplementation for 8-12 weeks on cognitive accuracy were marginally significant (SMD: .12; 95% CI: -.02-.26) and on reaction time was not significant (SMD: -.08; 95% CI: -.26 to .10). Remarkably, astaxanthin supplementation combined with regular training could enhance the fat oxidation (SMD: 2.56; 95% CI: 1.24-3.89), and significantly improve the physical performance (SMD: .62; 95% CI: .17-1.06). The subgroup analysis further showed significantly greater benefits when performing the aerobic exercises performance (SMD: .45; 95% CI: .13-.76), when the dose was ≥ 20 mg (SMD: .37; 95% CI: .11-.63), and when the supplementation duration was > 12 weeks (SMD: .66; 95% CI: .13-.63). We conclude that astaxanthin supplementation could significantly enhance aerobic exercise efficiency, especially at higher doses and for longer durations. Further studies based on large sample sizes are imperatively warranted.

The effect of polystyrene nanoplastics on arsenic-induced apoptosis in HepG2 cells.

Microplastics are detrimental to the environment. However, the combined effects of microplastics and arsenic (As) remain unclear. In this study, we investigated the combined effects of polystyrene (PS) microplastics and As on HepG2 cells. The results showed that PS microplastics 20, 50, 200, and 500 nm in size were taken up by HepG2 cells, causing a decrease in cellular mitochondrial membrane potential. The results of lactate dehydrogenase release and flow cytometry showed that PS microplastics, especially those of 50 nm, enhanced As-induced apoptosis. In addition, transcriptome analysis revealed that TP53, AKT1, CASP3, ACTB, BCL2L1, CASP8, XIAP, MCL1, NFKBIA, and CASP7 were the top 10 hub genes for PS that enhanced the role of As in HepG2 cell apoptosis. Our results suggest that nano-PS enhances As-induced apoptosis. Furthermore, this study is important for a better understanding of the role of microplastics in As-induced hepatotoxicity.

PDMS/magnetic lignin sponge for oil/water separation.

Recyclable, non-toxic, and degradable biological substrates contribute significantly to super-wetting surfaces. In this work, we prepared magnetic micro-nano super-hydrophobic surfaces through a robust solution with magnetic modified lignin particles as the supporting structure. A novel PDMS (polydimethylsiloxane)/magnetic lignin particle (lignin@Fe3O4)/PDA sponge composite was fabricated. Through dopamine (DA) self-polymerization, covalent deposition of magnetic lignin (ML), and PDMS silane modification, the magnetic super-hydrophobic polyurethane sponge composite (Sponge-P) was synthesized so that the Fe3O4 nanoscale microspheres wrapped with microscale lignin magnetic particles adhered to the sponge surface tighter and were barely dislodged. The as-prepared Sponge-P displayed excellent flexibility and a water contact angle of up to 152.2°. The super-hydrophobic sponge prepared with the proposed method was acid-base stable (pH = 2-12), self-cleaning, and suitable for high-salinity seawater. The magnetic super-hydrophobic sponge has good oil-water separation ability and can absorb 43 times its own weight of oil. In the meantime, due to the introduction of magnetic materials into lignin, we not only constructed micro-nanostructures to improve the surface super-hydrophobicity, but also made Sponge-P have the function of magnetic recovery, which has a unique advantage in treating oily wastewater.

Exosomal miRNA analysis provides new insights into exposure to nanoplastics and okadaic acid.

As an emerging environmental pollutant, nanoplastics (NPs) have attracted wide attention in terms of their impact on the ecological environment and human health. Currently, researches on the cytotoxicity of NPs mainly focus on oxidative stress, damage to the cell membrane and organelles, induction of immune response and genotoxicity. Okadaic acid (OA) is the main component of diarrheal shellfish toxin. Based on the previous combined toxicity exploration of polystyrene (PS) NPs and (OA) to human gastric adenocarcinoma (AGS) cells, cell-derived exosomes were extracted and exosomal miRNA profiles were analyzed for the first time in this study. The results showed that the composition of miRNAs varied after the exposure of NPs and OA. Specifically, the expression of miR-1-3p in both PS-Exo and PS-OA-Exo was significantly reduced. And the expression of miR-1248 was upregulated most significantly by comparing the DE miRNAs between PS-Exo and PS-OA-Exo. MiR-1-3p and miR-1248 may be the key genes for the combined toxicity of NPs and OA. After analysis, we found that both the decreased expression of miR-1-3p and the increased expression of miR-1248 can increase the expression of FN1 and affect DNA replication, which was surprisingly consistent with the results of our previous cytotoxicity studies. Since exosomal miRNAs are selectively encapsulated by donor cell, we speculate that the changes of exosomal miRNAs may due to the synchronous changes of intracellular environment and the downregulation of intracellular FN1 may be attributed to decreased expression of miR-1-3p and increased expression of miR-1248 in donor cells. Accordingly, we come to the conclusion that the changes of miRNAs in the exosomes derived from AGS cells after environmental stimulation could reflect the biological effects of donor cells.

Psychosocial resources moderate the association between stress and insomnia among patients with digestive system cancers.

This study explored the profiles of psychosocial resources combined with resilience and family care, and analyzed their moderating effects on the relationship between stress and insomnia in patients with digestive system cancers. A total of 366 patients were recruited to participate in this study from two tertiary hospitals in China. They were assessed using the Perceived Stress Scale - 4 items, Insomnia Severity Index, Family Concern Index Questionnaire, and 10-item Connor-Davidson Resilience Scale. Latent profile analysis and the BCH (Bolck, Croon & Hagenaars) method were used to identify the subtypes and estimate the moderating role of psychosocial coping resources. About 62.3% of participants had insomnia symptoms. Insomnia was positively correlated to the stress (r = 0.25, P < 0.001). The latent classes were the low resources class (32.8%), the medium resources class (46.1%), and high resources class (21.1%). Among these, in low (estimate value = 0.563, P = 0.003) and medium (estimate value = 0.301, P = 0.029) resources class, stress had an effect on insomnia. There was no association between stress and insomnia in high resources class (estimate value = 0.165, P = 0.637). Stress might be associated with to insomnia problems, whereas patients with high psychosocial resources are more not vulnerable. Interventions to improve family function and resilience could contribute to easing the insomnia of patients with digestive system cancers.

When experiencing a surgery: Gastrointestinal cancer patients' longitudinal trajectories in psychological stress and their association with quality of recovery.

Objective: Surgical treatment, particularly for gastrointestinal cancer, is a burdensome prospect for many patients. Psychological stress is a common complaint; however, little is known about its patterns in perioperative patients. This study aimed to identify distinct trajectories of perioperative stress and explore antecedent factors and hospitalization outcomes among different trajectories in patients with gastrointestinal cancer. Methods: A longitudinal study was conducted on 203 patients with gastrointestinal surgical cancer at a specialized oncology hospital in China. Psychological stress was assessed at five perioperative time points (1-3 days before surgery; 1-3 days, 4-6 days, 7-9 days after surgery, and before discharge). A growth mixture model was used to analyze the potential stress trajectories. Multinomial logistic regression was used to identify the characteristics associated with different trajectories. Results: Three stress trajectories were identified: recovery class (RC, 60.6%), chronic class (CC, 29.5%), and deterioration class (DC, 9.9%). Compared with CC, RC exhibited a shorter length of stay and better recovery quality, and was related to employment, low illness perception, and positive coping; DC reported lower recovery quality from 7 to 9 days after surgery to discharge and was associated with poor education level, history of surgery, stoma, smoking, and preoperative insomnia. Conclusions: Most surgical patients were insulated from stress due to psychosocial resources, and thus displayed good recovery. However, many patients had moderate stress that did not improve or worsen over the perioperative period, which still needs to be screened and provided with early stress management.

Efficacy of a Mixed Peroxyorganic Acid Antimicrobial Wash Solution against Salmonella, Escherichia coli O157:H7, or Listeria monocytogenes on Cherry Tomatoes.

ABSTRACT: A study was conducted to evaluate a new organic mixed peroxyacid solution produce wash composed of a combination of organic acids (lactic acid and one or more fruit acids) and hydrogen peroxide for activity against foodborne pathogens. The mixed peroxyacid was challenged against Salmonella enterica, Escherichia coli O157:H7, and Listeria monocytogenes in suspension or on the surface of dip-inoculated cherry tomatoes. Cherry tomatoes were also treated with 8 ppm of free chlorine in the form of sodium hypochlorite. When tested against planktonic cells of Salmonella and E. coli O157:H7 in pure culture for 120 s, these pathogens were reduced by 7.5 and 7.1 log CFU/mL, respectively, by the 0.40% peroxyacid solution, and L. monocytogenes was decreased by 5.0 log CFU/mL by the 0.80% solution. When cherry tomatoes were dip inoculated and treated with 8 ppm of free chlorine, Salmonella and E. coli O157:H7 populations decreased by 2.5 and 2.6 log CFU/g, respectively; these reductions were not significantly different from those obtained after sterile water rinses. However, the 1.0% peroxyacid solution reduced the same microorganisms by 3.8 and 3.4 log CFU/g, respectively, which was significantly greater (P < 0.05) than the reductions achieved by the 2-min sterile water rinse. For tomatoes dip inoculated with L. monocytogenes, populations were reduced by 3.5 log CFU/g by the 1.0% peroxyacid solution, which was significantly greater (P < 0.05) than reductions achieved by 8 ppm of free chlorine (2.6 log CFU/g) or sterile water (1.7 log CFU/g). These results indicate that this peroxyacid combination is an effective organic antimicrobial agent for preventing cross-contamination during the washing of cherry tomatoes and can inactivate S. enterica, E. coli O157:H7, and L. monocytogenes by up to 3.8, 3.4, and 3.5 log CFU/g, respectively.

Mechanochemical Synthesis of Porous Carbons and Their Applications in Catalysis.

Porous carbons have shown considerable potential in catalysis as either as supports or metal-free catalysts. Various methods based on solution chemistry have been intensively developed for the preparation of porous carbon-based catalysts with controllable morphology, pore structure, surface chemical property as well as the desired active sites. Nowadays, mechanochemical synthesis, a re-emerging strategy, has become more and more popular in the synthesis of porous carbons, due to its feasibility and high synthetic efficiency under solvent-free condition. This Minireview presents recent advances in the mechanochemical synthesis of porous carbons by ball milling, and their applications in catalysis. It starts a brief introduction of the characteristics and work mechanism of ball milling, and then discuss the preparation of porous carbons as metal-free catalysts and carbon-supported metal catalysts. Finally, some issues and further opportunities for the mechanochemical synthesis of porous carbon-based catalysts are proposed and discussed.

Hard Carbon Nanosheets with Uniform Ultramicropores and Accessible Functional Groups Showing High Realistic Capacity and Superior Rate Performance for Sodium-Ion Storage.

Hard carbon attracts considerable attention as an anode material for sodium-ion batteries; however, their poor rate capability and low realistic capacity have motivated intense research effort toward exploiting nanostructured carbons in order to boost their comprehensive performance. Ultramicropores are considered essential for attaining high-rate capacity as well as initial Coulombic efficiency by allowing the rapid diffusion of Na+ and inhibiting the contact of the electrolyte with the inner carbon surfaces. Herein, hard carbon nanosheets with centralized ultramicropores (≈0.5 nm) and easily accessible carbonyl groups (CO)/hydroxy groups (OH) are synthesized via interfacial assembly and carbonization strategies, delivering a large capacity (318 mA h g-1 at 0.02 A g-1 ), superior rate capability (145 mA h g-1 at 5.00 A g-1 ), and approximately 95% of reversible capacity below 1.00 V. Notably, a new charge model favoring fast capacitive sodium storage with dual potential plateaus is proposed. That is, the deintercalation of Na+ from graphitic layers is manifested as the low-potential plateau region (0.01-0.10 V), contributing to stable insertion capacity; meanwhile, the surface desodiation process of the CO and OH groups corresponds to the high-potential plateau region (0.40-0.70 V), contributing to a fast capacitive storage.

A Mechanochemical-Assisted Synthesis of Boron, Nitrogen Co-Doped Porous Carbons as Metal-Free Catalysts.

A green and convenient solid-state method assisted by mechanical energy is employed for the synthesis of boron (B) and nitrogen (N) co-doped porous carbons (B,N-Cs). Glutamic acid (Glu) and boric acid (H3 BO3 ) are used as the N-containing carbon precursor and boron source, respectively. This method is easy to perform and proved to be efficient towards co-doping B and N into the carbon matrix with high contents of B (7 atom %) and N (10 atom %). By adjusting the molar ratio of H3 BO3 to Glu, the surface chemical states of B and N could be readily modulated. When increasing H3 BO3 dosage, the pore size of B,N-Cs could be tuned ranging from micropores to mesopores with a Brunauer-Emmett-Teller (BET) surface area up to 940 m2 g-1 . Finally, the B,N-Cs were applied as metal-free catalysts for the cycloaddition of CO2 to epoxides, which outperform the N-doped carbon catalyst (NC-900) and the physically mixed catalyst of NC-900/B4 C. The enhanced activity is attributed to the cooperative effect between B and N sites. X-ray photoelectron spectroscopy (XPS) analysis reveals that BN3 in the B,N-Cs serves as a critical active site for the cooperative catalysis.

One-pot synthesis of unique skin-tissue-bone structured porous carbons for enhanced supercapacitor performance.

Introduction of hierarchical porous structure and heteroatom in porous carbons are always effective approaches to improve the capacitive performance for supercapacitor. However, it is still a challenge to achieve the desired structure characteristics by a convenient one-step synthesis. Herein, C16mimPF6, an ionic liquid, was introduced in the self-assembly process of poly-benzoxazine to obtain a unique skin-tissue-bone structured hierarchical porous carbon with homogeneous N, P co-doping after carbonization. As the key component, C16mimPF6 works not only as a structure-directing agent to form a hierarchical structure through microphase separation mechanism, thereby promoting the transfer of ion and electron, but also as a heteroatom precursor to contribute an additional pseudocapacitance by doping phosphorus atoms on carbon matrix. The obtained porous carbon displays a high gravimetric capacitance (Cg) of 209 F g-1 (especially in the carbons prepared without corrosive activation step), a good volumetric capacitance (Cv) of 132 F cm-3 and an excellent area-normalized capacitance (Ca) of 35 µF cm-2. Overall, this work opens a new way to design the polymer-derived carbons with easy heteroatoms doping and hierarchical porous structure.

Efficient Visible-to-NIR Spectral Conversion for Polycrystalline Si Solar Cells and Revisiting the Energy Transfer Mechanism from Ce3+ to Yb3+ in Lu3Al5O12 Host.

The so-called Shockley-Queisser converting efficiency limit of Si solar cells is believed to be surpassed by using the spectral converter. However, searching for efficient spectral converting materials is still a challenging task. In this paper, efficient visible-to-NIR spectral conversion for polycrystalline Si solar cells has been demonstrated in Ce3+ and Yb3+ codoped Lu3Al5O12. Moreover, the underlying energy transfermechanism from Ce3+ to Yb3+ is systematically re-investigated by the detailed excitation and emission spectra as well as fluorescent decay curves, and our results demonstrate that fast metal-to-metal charge transfer from Ce3+ to nearby Yb3+ is the dominant energy transfermechanism. Finally, we provide new evidence that Ce4+-Yb2+ charge-transfer state is responsible for the relatively low quantum efficiency of NIR emission in Ce3+ and Yb3+ codoped system.

Hard@Soft Integrated Morning Glory Like Porous Carbon as a Cathode for a High-Energy Lithium Ion Capacitor.

A lithium ion capacitor (LIC) is a hybrid energy storage device that combines the energy storage mechanism of lithium ion batteries and supercapacitors and presents their complementary features. However, imbalances of the capacity and kinetics between cathode and anode still remain challenges. Herein, to address the issue of low capacity in the cathode, we constructed a morning glory like porous material crimped from an opening sandwich structure consisting of a hard carbon inner layer and soft carbon outer layer, by coating graphene oxide containing flaky phenolic resin with coal tar pitch followed by carbonization and activation. Both the hard@soft carbon integrated design and the reduced graphene oxide network cocontributed to a favorable electrical conductivity and a developed microporosity. To deal with the sluggish kinetics limitation of the anode, a structure-optimized MnO@C electrode prepared by pore creation of CO2 from an MnCO3@polydopamine precursor was chosen due to its excellent rate performance. The LIC with this configuration can deliver a maximum energy density of 117.6 Wh kg-1 and an favorable capacity retention of 76% after 3000 cycles at 2050 W kg-1. Furthermore, the energy density of 27.8 Wh kg-1 can still be delivered even at a high power density of 10250 W kg-1. In general, this well-designed hybrid capacitor has a potential to make up the gap between lithium ion batteries and supercapacitors.

Metal leachability from coal combustion residuals under different pHs and liquid/solid ratios.

Coal combustion residuals (CCRs) contain variable amounts of trace metals, which can negatively impact the environment. We analyzed metal concentrations and leachability of CCRs from seven coal-fired power plants from Florida. The purpose of this study was to characterize and assess metal leachability in representative CCRs samples from coal-fired power plants, including As, Ba, Cd, Cr, Pb, and Se. The specific objectives were to: (1) measure metal leachability under different pH conditions and liquid-to-solid ratios using USEPA Leaching Environmental Assessment Framework (LEAF) Methods 1313 and 1316, and (2) compare their leachability with those obtained by the Synthetic Precipitation Leaching Procedure (SPLP). All metals excluding Cd showed amphoteric behavior, presenting higher concentrations at low and high pH using LEAF Method 1313. The highest Cd leaching was observed at pH 2-4 and decreased at pH>7. SPLP results were highly variable when compared to the LEAF data. All metals except Ba exceeded the Florida Groundwater Cleanup Target Levels at all pH levels, however, metal leaching was low at typical soil pH of 4-9. Metal concentrations in fly ash decreased in most cases with increasing LS ratio. Therefore, due to potential leaching of some metals, evaluation is needed before beneficial use of CCRs.