Gradual effects of gradient concentrations of perfluorooctane sulfonate on the antioxidant ability and gut microbiota of red claw crayfish (Cherax quadricarinatus).

Perfluorooctane sulfonate (PFOS) is a typical persistent organic pollutant that is characterized by environmental persistence, bioaccumulation, and toxicity. In this study, we investigated the gut microbial response of the red claw crayfish Cherax quadricarinatus after 28 days of exposure to 0 ng/L, 1 ng/L, 10 µg/L, or 10 mg/L of PFOS as a stressor. We measured oxidative stress-related enzyme activities and expression of molecules related to detoxification mechanisms to evaluate the toxic effects of PFOS. We found that PFOS disturbed microbial homeostasis in the gut of C. quadricarinatus, resulting in increased abundance of the pathogen Shewanella and decreased abundance of the beneficial bacterium Lactobacillus. The latter especially disturbed amino acid transport and carbohydrate transport. We also found that the activities of glutathione S-transferase and glutathione peroxidase were positively correlated with the expression levels of cytochrome P450 genes (GST1-1, GSTP, GSTK1, HPGDS, UGT5), which are products of PFOS-induced oxidative stress and play an antioxidant role in the body. The results of this study provided valuable ecotoxicological data to better understand the biological fate and effects of PFOS in C. quadricarinatus.

Research on the Application of Molecular Image Processing in Rice Quality Inspection.

Objective: With the improvement of living standards, consumers are paying more and more attention to the quality of rice. Traditional rice quality detection relies on human sensory judgment, which is inaccurate and inefficient. With the continuous development of molecular imaging technology, more and more scholars at home and abroad have begun to pay attention to its application in the nondestructive testing of agricultural products. Molecular imaging technology combines the advantages of spectral technology and image technology, which can achieve rapid, nondestructive and accurate detection of rice quality. In this paper, taking rice as the research object, we carried out nondestructive detection research on rice varieties, moisture and starch content using molecular imaging technology. We proposed a rapid detection method based on molecular imaging technology for rice variety identification, moisture content and starch content. Molecular images of the rice samples from four origins were obtained using a molecular imaging system, the regions of interest of the rice were identified and, spectral data, textural features and morphological features of the rice were extracted. Spectral, textural and morphological features were selected by principal component analysis (PCA), and nine feature wavelengths were obtained and an optimal model was established with an accuracy of 91.67%, which demonstrated the feasibility of molecular imaging. By comparing the models, the BCC-LS-SVR model based on the RB function had the highest accuracy with R2 of 0.989, RMSEP of 0.767%, R2 of 0.985, and RMSEC of 0.591%. Moreover, starchy rice was detected using molecular imaging. The PCA-SVR model based on the RBF kernel function had the highest accuracy with R2 of 0.989, RMSEC of 0.445%, R2 of 0.991, and RMSEP of 0.669%. Our models demonstrated high accuracy in identifying rice varieties, as well as quantifying moisture and starch content, showcasing the feasibility of molecular imaging technology in rice quality assessment. This research offers a rapid, nondestructive, and accurate method for rice quality assessment, promising significant benefits for agricultural producers and consumers.

Metal-Sulfur Interfaces as the Primary Active Sites for Catalytic Hydrogenations.

The determination of catalytically active sites is crucial for understanding the catalytic mechanism and providing guidelines for the design of more efficient catalysts. However, the complex structure of supported metal nanocatalysts (e.g., support, metal surface, and metal-support interface) still presents a big challenge. In particular, many studies have demonstrated that metal-support interfaces could also act as the primary active sites in catalytic reactions, which is well elucidated in oxide-supported metal nanocatalysts but is rarely reported in carbon-supported metal nanocatalysts. Here, we fill the above gap and demonstrate that metal-sulfur interfaces in sulfur-doped carbon-supported metal nanocatalysts are the primary active sites for several catalytic hydrogenation reactions. A series of metal nanocatalysts with similar sizes but different amounts of metal-sulfur interfaces were first constructed and characterized. Taking Ir for quinoline hydrogenation as an example, it was found that their catalytic activities were proportional to the amount of the Ir-S interface. Further experiments and density functional theory (DFT) calculations suggested that the adsorption and activation of quinoline occurred on the Ir atoms at the Ir-S interface. Similar phenomena were found in p-chloronitrobenzene hydrogenation over the Pt-S interface and benzoic acid hydrogenation over the Ru-S interface. All of these findings verify the predominant activity of metal-sulfur interfaces for catalytic hydrogenation reactions and contribute to the comprehensive understanding of metal-support interfaces in supported nanocatalysts.

Sleep deprivation boosts O2·- levels in the brains of mice as visualized by a Golgi apparatus-targeted ratiometric fluorescence nanosensor.

Sleep deprivation (SD) is highly prevalent in the modern technological world. Emerging evidence shows that sleep deprivation is associated with oxidative stress. At the organelle level, the Golgi apparatus actively participates in the stress response. In this study, to determine whether SD and Golgi apparatus stress are correlated, we rationally designed and fabricated a novel Golgi apparatus-targeted ratiometric nanoprobe called Golgi dots for O2·- detection. This probe exhibits high sensitivity and selectivity in cells and brain slices of sleep-deprived mice. Golgi dots can be readily synthesized by coprecipitation of Golgi-F127, an amphiphilic polymer F127 modified with a Golgi apparatus targeting moiety, caffeic acid (CA), the responsive unit for O2·-, and red emissive carbon nanodots (CDs), which act as the reference signal. The fluorescence emission spectrum of the developed nanoprobe showed an intense peak at 674 nm, accompanied by a shoulder peak at 485 nm. As O2·- was gradually added, the fluorescence at 485 nm continuously increased; in contrast, the emission intensity at 674 nm assigned to the CDs remained constant, resulting in the ratiometric sensing of O2·-. The present ratiometric nanoprobe showed high selectivity for O2·- monitoring due to the specific recognition of O2·- by CA. Moreover, the Golgi dots exhibited good linearity with respect to the O2·- concentration within 5 to 40 µM, and the limit of detection (LOD) was ~ 0.13 µM. Additionally, the Golgi dots showed low cytotoxicity and an ability to target the Golgi apparatus. Inspired by these excellent properties, we then applied the Golgi dots to successfully monitor exogenous and endogenous O2·- levels within the Golgi apparatus. Importantly, with the help of Golgi dots, we determined that SD substantially elevated O2·- levels in the brain.

Occurrence and Risk Assessment of Pesticides, Phthalates, and Heavy Metal Residues in Vegetables from Hydroponic and Conventional Cultivation.

Hydroponic cultivation of fresh produce is gaining popularity worldwide, but few studies have provided a comparative assessment of hydroponic and conventional soil-based vegetables. In this study, we analyzed a series of hazardous chemicals, including 120 pesticides, 18 phthalates (PAEs), and 2 heavy metals (lead and cadmium) in four vegetable commodities (lettuces, celeries, tomatoes, and cucumbers) from hydroponic and conventional soil-based cultivation. Our study showed that at least one pesticide was present in 84% of the conventionally grown samples, whereas only 30% of the hydroponic samples contained detectable pesticide residues. Regarding the total PAE concentrations, there was no significant difference between conventional and hydroponic vegetables. The lead and cadmium residues in conventionally cultivated vegetables were significantly higher than in those produced from hydroponic cultivation. Lead is the primary heavy metal pollutant across all vegetable samples. The hazard index (HI) values of the hydroponic and conventional vegetables were 0.22 and 0.64, respectively. Since both values are below one, the exposure to these hazardous chemicals through consumption of the studied vegetables may not pose a significant health risk. The HI values also suggested that the health risks of eating hydroponic vegetables are lower than for conventional soil-based vegetables.

Assessing Seasonal Effects on Identification of Cultivation Methods of Short-Growth Cycle Brassica chinensis L. Using IRMS and NIRS.

Seasonal (temporal) variations can influence the δ13C, δ2H, δ18O, and δ15N values and nutrient composition of organic (ORG), green (GRE), and conventional (CON) vegetables with a short growth cycle. Stable isotope ratio mass spectrometry (IRMS) and near-infrared spectroscopy (NIRS) combined with the partial least squares-discriminant analysis (PLS-DA) method were used to investigate seasonal effects on the identification of ORG, GRE, and CON Brassica chinensis L. samples (BCs). The results showed that δ15N values had significant differences among the three cultivation methods and that δ13C, δ2H, and δ18O values were significantly higher in winter and spring and lower in summer. The NIR spectra were relatively clustered across seasons. Neither IRMS-PLS-DA nor NIRS-PLS-DA could effectively identify all BC cultivation methods due to seasonal effects, while IRMS-NIRS-PLS-DA combined with Norris smoothing and derivative pretreatment had better predictive abilities, with an 89.80% accuracy for ORG and BCs, 88.89% for ORG and GRE BCs, and 75.00% for GRE and CON BCs. The IRMS-NIRS-PLS-DA provided an effective and robust method to identify BC cultivation methods, integrating multi-seasonal differences.

Satellite microwave measurements complementary to fire weather improve the assessment of fires among different biomes in Southeast Asia.

Microwaves have the advantage of penetrating vegetation and exhibit sensitivity to properties such as vegetation water content (VWC); yet, their potential utility in the fire domain is infrequently investigated. This study elucidates the different impacts of the microwave VWC index EDVI on fire radiative energy (FRE) across various biome types and the significant predictive power for high-severity fires (defined based on FRE) in mainland Southeast Asia. While EDVI exhibits lower predictive power for high severe fires compared to the commonly used fire weather indices (e.g., FWI), an enhancement is observed when these predictors are used in combination. Either by employing EDVI or fire weather indices, the predictability of fires is found to be highest over forests and lowest over croplands. Factors such as increasing human influence and fuel limitation in croplands are likely reducing the roles of VWC and weather on fires, contributing to the lower prediction skill of EDVI and fire weather. These results indicate the usefulness of microwave VWC index in fire studies. Although fire weather presents more considerable impacts on fires, the microwave VWC index seem to still provide some complementary information in fire danger assessment.

[Determination of 14 perfluoroalkyl substances in Chinese mitten crab by multi-plug filtration cleanup coupled with ultra-performance liquid chromatography-tandem mass spectrometry].

Perfluoroalkyl substances (PFASs) have become a new food-safety problem. Dietary intake is a major pathway of human exposure to PFASs. Chinese mitten crab (Eriocheir sinensis) is a high-end aquaculture product popular among consumers in China. Conventional extraction methods for PFASs are cumbersome and time consuming, and result in incomplete purification; thus, this technique does not meet the requirements for PFAS detection. Herein, an analytical strategy was established for the rapid detection of 14 PFASs in Chinese mitten crab based on multi-plug filtration cleanup (m-PFC) and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The carbon-chain length of the 14 PFASs analyzed in this study ranged from 4 to 14, and they are perfluorobutanoic acid (PFBA), perfluoro-n-pentanoic acid (PFPeA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), perfluoroundecanoic acid (PFUnDA), perfluorododecanoic acid (PFDoDA), perfluorotetradecanoic acid (PFTeDA), perfluoro-1-butane sulfonic acid (PFBS), perfluoro-1-hexane sulfonic acid (PFHxS), perfluoro-1-octane sulfonic acid (PFOS), and perfluoro-1-decanesulfonate (PFDS). The m-PFC column was prepared using carboxy-based multiwalled carbon nanotubes, and used to reduce the interference of sample impurities. The samples were extracted with 5 mL of 0.1% formic acid aqueous solution, 15 mL of acetonitrile and extraction salt (2 g Na2SO4 and 2 g NaCl). The supernatant (10 mL) was purified using the m-PFC column, concentrated to near dryness under nitrogen, and then redissolved in 1 mL of methanol. Finally, the sample solution was filtered through a 0.22 µm polypropylene syringe filter for UPLC-MS/MS analysis. The target analytes were separated using a Shimadzu Shim-pack G1ST-C18 chromatographic column (100 mm×2.1 mm, 2 µm) using methanol (A) and 5 mmol/L ammonium acetate aqueous solution (B) as the mobile phases via gradient elution. The linear gradient program were as follows: 0-0.5 min, 10%A-35%A; 0.5-3 min, 35%A-60%A; 3-5 min, 60%A-100%A; 5-6.5 min, 100%A; 6.5-7 min, 100%A-10%A. The target analytes were analyzed using negative electrospray ionization in multiple-reaction monitoring mode, and quantitative analysis was performed using the internal standard method. In this study, we optimized the mobile-phase system as well as the extraction solvent, time, volume, and salt. The 14 PFASs exhibited good peak shapes and sensitivities when the 5 mmol/L ammonium acetate solution-methanol system was used as the mobile phase. Compared with acetonitrile or methanol alone, the extraction efficiencies of the 14 PFASs were significantly improved when 5 mL of 0.1% formic acid aqueous solution was added, followed by 15 mL of acetonitrile. The extraction efficiencies of the 14 PFASs did not differ significantly when the extraction time was within 3-15 min. The extraction salt (MgSO4, Na2SO4, NaCl, (NH4)2SO4, and Na2SO4+NaCl) significantly affected the extraction efficiencies of the 14 PFASs. The highest extraction efficiencies of the 14 PFASs, which ranged from 47.9% to 121.9%, were obtained when Na2SO4+NaCl was used as the extraction salt. Under the optimal experimental conditions, good linearities (R2=0.998-0.999) were obtained for seven PFASs (PFBS, PFHxA, PFHpA, PFHxS, PFDA, PFDoDA, PFTeDA) at 0.10-100 µg/L, and seven PFASs (PFBA, PFPeA, PFOA, PFOS, PFNA, PFUnDA, PFDS) at 0.50-100 µg/L. The average spiked recoveries for the 14 PFASs in Chinese mitten crabs at three levels ranged from 73.1% to 120%, with relative standard deviations (RSDs) in the range of 1.68%-19.5%(n=6). The limits of detection (LODs) and quantification (LOQs) of the 14 PFASs were in the range of 0.03-0.15 and 0.10-0.50 µg/kg, respectively. The developed method was applied to the analysis of crab samples collected from three farms in Shanghai, and PFASs with total concentrations of 3.52-37.77 µg/kg were detected in all samples. The detection frequencies for PFDA, PFUnDA, PFDoDA, PFTeDA, and PFOS were 100%. PFDA, PFUnDA, PFOS, and PFDoDA were the most abundant congeners, accounting for 31.2%, 30.6%, 15.0%, and 10.9%, respectively, of the 14 PFASs detected. The proposed method is simple, efficient, accurate, and suitable for the rapid analysis of 14 PFASs in Chinese mitten crabs.

The Role of Tumor Metabolic Reprogramming in Tumor Immunity.

The occurrence and development of tumors require the metabolic reprogramming of cancer cells, namely the alteration of flux in an autonomous manner via various metabolic pathways to meet increased bioenergetic and biosynthetic demands. Tumor cells consume large quantities of nutrients and produce related metabolites via their metabolism; this leads to the remodeling of the tumor microenvironment (TME) to better support tumor growth. During TME remodeling, the immune cell metabolism and antitumor immune activity are affected. This further leads to the escape of tumor cells from immune surveillance and therefore to abnormal proliferation. This review summarizes the regulatory functions associated with the abnormal biosynthesis and activity of metabolic signaling molecules during the process of tumor metabolic reprogramming. In addition, we provide a comprehensive description of the competition between immune cells and tumor cells for nutrients in the TME, as well as the metabolites required for tumor metabolism, the metabolic signaling pathways involved, and the functionality of the immune cells. Finally, we summarize current research targeted at the development of tumor immunotherapy. We aim to provide new concepts for future investigations of the mechanisms underlying the metabolic reprogramming of tumors and explore the association of these mechanisms with tumor immunity.

Developmental Mapping of Hair Follicles in the Embryonic Stages of Cashmere Goats Using Proteomic and Metabolomic Construction.

The hair follicle (HF) is the fundamental unit for fleece and cashmere production in cashmere goats and is crucial in determining cashmere yield and quality. The mechanisms regulating HF development in cashmere goats during the embryonic period remain unclear. Growing evidence suggests that HF development involves complex developmental stages and critical events, and identifying the underlying factors can improve our understanding of HF development. In this study, samples were collected from embryonic day 75 (E75) to E125, the major HF developmental stages. The embryonic HFs of cashmere goats were subjected to proteomic and metabolomic analyses, which revealed dynamic changes in the key factors and signalling pathways controlling HF development at the protein and metabolic levels. Gene ontology and the Kyoto Encyclopaedia of Genes and Genomes were used to functionally annotate 1784 significantly differentially expressed proteins and 454 significantly differentially expressed metabolites enriched in different HF developmental stages. A joint analysis revealed that the oxytocin signalling pathway plays a sustained role in embryonic HF development by activating the MAPK and Ca2+ signalling pathways, and a related regulatory network map was constructed. This study provides a global perspective on the mechanism of HF development in cashmere goats and enriches our understanding of embryonic HF development.

Determination of 25 polybrominated diphenyl ethers in Chinese mitten crab ecosystems by gas chromatography-mass spectrometry.

A sensitive and reliable method for determining 25 polybrominated diphenyl ethers (PBDEs) in Chinese mitten crabs and their ecosystems ranging from the growing environment to edible feed by gas chromatography coupled to triple quadrupole mass spectrometry with advanced electron ionization (GC-AEI-MS/MS) was developed and validated. Accelerated solvent extraction (ASE) and liquid-liquid extraction were used to extract solid and water samples, respectively. On the basis of a traditional acid-base silica column, deactivated silica was added and n-hexane elution was used to increase the effect of separation and purification. Two oven temperature programs were applied to achieve good separation of low brominated congeners and increase the sensitivity of high brominated congeners. The method provided good linearity (>0.9996). The recoveries of four matrices were in the range of 82-115% and the method quantification limits (MQLs) in crabs, feed, sediment and water ranged from 0.36-6 pg per g wet weight, 0.69-22.29 pg per g dry weight, 1.02-25.26 pg per g dry weight, and 2.43-40.14 pg L-1, respectively. The proposed method was used for ten samples from two aquatic sites and PBDEs were detected in Chinese mitten crabs, commercial feed and sediment, with the highest in crabs. This analytical technique can be used to monitor the content and the accumulation behavior of PBDEs in Chinese mitten crab ecosystems or other aquaculture systems.

Transspinal Focused Ultrasound Suppresses Spinal Reflexes in Healthy Rats.

OBJECTIVES: Low-intensity, focused ultrasound (FUS) is an emerging noninvasive neuromodulation approach, with improved spatial and temporal resolution and penetration depth compared to other noninvasive electrical stimulation strategies. FUS has been used to modulate circuits in the brain and the peripheral nervous system, however, its potential to modulate spinal circuits is unclear. In this study, we assessed the effect of trans-spinal FUS (tsFUS) on spinal reflexes in healthy rats. MATERIALS AND METHODS: tsFUS targeting different spinal segments was delivered for 1 minute, under anesthesia. Monosynaptic H-reflex of the sciatic nerve, polysynaptic flexor reflex of the sural nerve, and withdrawal reflex tested with a hot plate were measured before, during, and after tsFUS. RESULTS: tsFUS reversibly suppresses the H-reflex in a spinal segment-, acoustic pressure- and pulse-repetition frequency (PRF)-dependent manner. tsFUS with high PRF augments the degree of homosynaptic depression of the H-reflex observed with paired stimuli. It suppresses the windup of components of the flexor reflex associated with slower, C-afferent, but not faster, A- afferent fibers. Finally, it increases the latency of the withdrawal reflex. tsFUS does not elicit neuronal loss in the spinal cord. CONCLUSIONS: Our study provides evidence that tsFUS reversibly suppresses spinal reflexes and suggests that tsFUS could be a safe and effective strategy for spinal cord neuromodulation in disorders associated with hyperreflexia, including spasticity after spinal cord injury and painful syndromes.

Effects of Thiamethoxam and Fenvalerate Residue Levels on Light-Stable Isotopes of Leafy Vegetables.

Accurate identification of the rational and standardized use of pesticides is important for the sustainable development of agriculture while maintaining a high quality. The insecticides thiamethoxam and fenvalerate and the vegetables spinach, cabbage, and lettuce were used here as study objects. Descriptive analysis and primary reaction kinetic equations were used to analyze the changes in metabolic residues of the two insecticides after different numbers of application in three vegetables. The effects of pesticide residue levels on the δ13C, δ15N, δ2H, and δ18O values of vegetables were analyzed by one-way analysis of variance and correlation analysis. Partial least squares discriminant analysis (PLS-DA) was applied to build discrimination models of the vegetables with different pesticide residues based on stable isotopes. The results showed that the first degradation residues of thiamethoxam and fenvalerate in spinach, cabbage, and lettuce conformed to primary reaction kinetic equations, but the degradation half-lives were long, and accumulation occurred in the second application. The differences in the four stable isotope ratios in the control group of the three vegetables were statistically significant, and two-thirds of the stable isotope ratios in the three vegetables with different numbers of pesticide applications were significantly different. The δ13C and δ15N values of spinach, the δ13C, δ15N, and δ2H values of cabbage, and the δ13C, δ15N, δ2H, and δ18O values of lettuce were significantly correlated with different residues of thiamethoxam and/or fenvalerate applications. The control groups of the three vegetables, spinach-thiamethoxam-first, spinach-thiamethoxam-second, cabbage-thiamethoxam-second, cabbage-fenvalerate-first, and lettuce-thiamethoxam-first, were fully identified by PLS-DA models, while the identification models of other vegetables containing pesticide residues still need to be further improved. The results provide technical support for identifying the rational use of pesticides in vegetables and provide a reference method for guaranteeing the authenticity of green and organic vegetables.

Effect of Fibroblast Growth Factor 10 and an Interacting Non-Coding RNA on Secondary Hair Follicle Dermal Papilla Cells in Cashmere Goats' Follicle Development Assessed by Whole-Transcriptome Sequencing Technology.

Cashmere, a keratinised product of secondary hair follicles (SHFs) in cashmere goats, holds an important place in international high-end textiles. However, research on the complex molecular and signal regulation during the development and growth of hair follicles (HFs), which is essential for the development of the cashmere industry, is limited. Moreover, increasing evidence indicates that non-coding RNAs (ncRNAs) participate in HF development. Herein, we systematically investigated a competing endogenous RNA (ceRNA) regulatory network mediated by circular RNAs (circRNAs), microRNAs (miRNAs), and messenger RNAs (mRNAs) in skin samples of cashmere goat embryos, using whole-transcriptome sequencing technology. We obtained 6468, 394, and 239 significantly differentially expressed mRNAs, circRNAs, and miRNAs, respectively. These identified RNAs were further used to construct a ceRNA regulatory network, mediated by circRNAs, for cashmere goats at a late stage of HF development. Among the molecular species identified, miR-184 and fibroblast growth factor (FGF) 10 exhibited competitive targeted interactions. In secondary HF dermal papilla cells (SHF-DPCs), miR-184 promotes proliferation, inhibits apoptosis, and alters the cell cycle via the competitive release of FGF10. This study reports that FGF10 and its interaction with ncRNAs significantly affect SHF-DPCs, providing a reference for research on the biology of HFs in cashmere goats and other mammals.

Revealing the Combined Effect of Active Sites and Intra-Particle Diffusion on Adsorption Mechanism of Methylene Blue on Activated Red-Pulp Pomelo Peel Biochar.

Phosphoric acid-activated biochar has been proven to be a promising adsorbent for pollutant removal in an aqueous solution. It is urgent to understand how surface adsorption and intra-particle diffusion synergistically contribute to the adsorption kinetic process of dyes. In this work, we prepared a series of PPC adsorbents (PPCs) from red-pulp pomelo peel under different pyrolysis temperatures (150-350 °C), which have a broad specific surface area range from 3.065 m2/g to 1274.577 m2/g. The active sites on the surface of PPCs have shown specific change laws of decreasing hydroxyl groups and increasing phosphate ester groups occurring as the pyrolysis temperature rises. Both reaction models (PFO and PSO models) and diffusion models (intra-particle diffusion models) have been applied to simulate the adsorption experimental data to verify the hypothesis deduced from the Elovich model. PPC-300 exhibits the highest adsorption capacity of MB (423 mg/g) under given conditions. Due to its large quantities of active sites on the external and internal surfaces (1274.577 m2/g), a fast adsorption equilibrium can be achieved within 60 min (with an initial MB concentration of 100 ppm). PPC-300 and PPC-350 also exhibit an intra-particle-diffusion-controlled adsorption kinetic process with a low initial MB concentration (100 ppm) or at the very beginning and final stage of adsorption with a high initial MB concentration (300 ppm) at 40 °C, considering that the diffusion is likely hindered by adsorbate molecules through internal pore channels at the middle stage of adsorption in these cases.

Dissipation, Bioconcentration and Dietary Risk Assessment of Thiamethoxam and Its Metabolites in Agaricus bisporus and Substrates under Different Application Methods.

In order to acquire scientific evidence for the application of thiamethoxam (TMX) in Agaricus bisporus cultivation, residue and dissipation experiments for field trials were performed with the application of TMX in compost and casing soil, respectively. An effective QuEChERS method was established to analyze TMX and its two metabolites, clothianidin (CLO) and thiamethoxam-urea (TMX-urea), in compost, casing soil, and fruiting bodies. The results indicated that the TMX dissipation half-lives (t1/2) at dosages of 10 and 50 mg kg-1 were 19.74 d (day) and 28.87 d in compost and 33.54 d and 42.59 d in casing soil, individually. TMX, CLO, and TMX-urea were observed after TMX application in compost and casing soil. For TMX applied to the casing soil, only TMX residues were detected in fruiting bodies with bioconcentration factors (BCFs) of 0.0003~0.0009. In addition, both the chronic risk quotient (RQ) and acute risk quotient (HQ) values of TMX in fruiting bodies were far less than 1, which means the dietary health risks to humans were acceptable. However, in the TMX application to the compost, these analytes were not detected in the fruiting bodies. This suggested that the application of TMX in compost was safer than in casing soil during A. bisporus cultivation.

A chemiresistive-potentiometric multivariate sensor for discriminative gas detection.

Highly efficient gas sensors able to detect and identify hazardous gases are crucial for numerous applications. Array of conventional single-output sensors is currently limited by problems including drift, large size, and high cost. Here, we report a sensor with multiple chemiresistive and potentiometric outputs for discriminative gas detection. Such sensor is applicable to a wide range of semiconducting electrodes and solid electrolytes, which allows to tailor and optimize the sensing pattern by tuning the material combination and conditions. The sensor performance is boosted by equipping a mixed-conducting perovskite electrode with reverse potentiometric polarity. A conceptual sensor with dual sensitive electrodes achieves superior three-dimensional (sub)ppm sensing and discrimination of humidity and seven hazardous gases (2-Ethylhexanol, ethanol, acetone, toluene, ammonia, carbon monoxide, and nitrogen dioxide), and enables accurate and early warning of fire hazards. Our findings offer possibilities to design simple, compact, inexpensive, and highly efficient multivariate gas sensors.

Sabatier Phenomenon in Hydrogenation Reactions Induced by Single-Atom Density.

The Sabatier principle is a fundamental concept in heterogeneous catalysis that provides guidance for designing optimal catalysts with the highest activities. For the first time, we here report a new Sabatier phenomenon in hydrogenation reactions induced by single-atom density at the atomic scale. We produce a series of Ir single-atom catalysts (SACs) with a predominantly Ir1-P4 coordination structure with densities ranging from 0.1 to 1.7 atoms/nm2 through a P-coordination strategy. When used as the catalysts for hydrogenation, a volcano-type relationship between Ir single-atom density and hydrogenation activity emerges, with a summit at a moderate density of 0.7 atoms/nm2. Mechanistic studies show that the balance between adsorption and desorption strength of the activated H* on Ir single atoms is found to be a key factor for the Sabatier phenomenon. The transferred Bader charge on these Ir SACs is proposed as a descriptor to interpret the structure-activity relationship. In addition, the maximum activity and selectivity can be simultaneously achieved in chemoselective hydrogenation reactions with the optimized catalyst due to the uniform geometric and electronic structures of single sites in SACs. The present study reveals the Sabatier principle as an insightful guidance for the rational design of more efficient and practicable SACs for hydrogenation reactions.

Regulating the electronic structure through charge redistribution in dense single-atom catalysts for enhanced alkene epoxidation.

Inter-site interaction in densely populated single-atom catalysts has been demonstrated to have a crucial role in regulating the electronic structure of metal atoms, and consequently their catalytic performances. We herein report a general and facile strategy for the synthesis of several densely populated single-atom catalysts. Taking cobalt as an example, we further produce a series of Co single-atom catalysts with varying loadings to investigate the influence of density on regulating the electronic structure and catalytic performance in alkene epoxidation with O2. Interestingly, the turnover frequency and mass-specific activity are significantly enhanced by 10 times and 30 times with increasing Co loading from 5.4 wt% to 21.2 wt% in trans-stilbene epoxidation, respectively. Further theoretical studies reveal that the electronic structure of densely populated Co atoms is altered through charge redistribution, resulting in less Bader charger and higher d-band center, which are demonstrated to be more beneficial for the activation of O2 and trans-stilbene. The present study demonstrates a new finding about the site interaction in densely populated single-atom catalysts, shedding insight on how density affects the electronic structure and catalytic performance for alkene epoxidation.