Changes in coal waste DOM chemodiversity and Fe/Al oxides during weathering drive the fraction conversion of heavy metals.

The long-term accumulation of coal waste on the surface during natural weathering leads to the inevitable migration of heavy metals contained in the coal waste, which increases the likelihood of environmental contamination and health risks. Dissolved organic matter (DOM) and Fe/Al oxides play crucial roles in the transformation and bioavailability of heavy metals. Thus, we analyzed the Fe/Al oxide content and DOM molecular composition in coal waste with different degrees of weathering and explored the influence of DOM chemical diversity and Fe/Al oxides on the potential mobility of heavy metals. Results showed that weathering-driven decrease in Fe oxides (Fed, FeO, and Fep decreased from 82.4, 37.5, and 3.6 mg∙L-1 to 41.3, 24.7, and 2.3 mg∙L-1, respectively) led to decreases in the reducible fractions of V and Cr. The potential environmental risks of more toxic metals of Cd and As, also increased as a result of the residual fractions decreased to 32.6 % and 41.3 %, respectively. Weathering caused an increase in oxygen-to­carbon ratio, double-bond equivalent, modified aromaticity index, nominal oxidation state of carbon, and molecular diversity and a decrease in (m/z)w and (H/C)w, suggesting that the DOM of highly weathered coal waste possessed high unsaturation, aromatic structures, hydrophilicity, and strong oxidative characteristics. Additionally, although VMF and CrMF showed significant negative correlations with O/C ratio, polyphenolic, carbohydrates, and condensed aromatics, pH remained a key environmental factor determining the potential environmental risks of V and Cr by changing the residual fractions. The mobilities of Cd and As were significantly negatively correlated with those of Fe/Al oxides, particularly Fed, FeO, Fep, and Alp. Our findings contribute to the understanding of the impact of weathering on the geochemical cycling of different coal waste components, providing priority options for environmental risk prevention and control in coal mining areas.

Modular access to chiral bridged piperidine-γ-butyrolactones via catalytic asymmetric allylation/aza-Prins cyclization/lactonization sequences.

Chiral functionalized piperidine and lactone heterocycles are widely spread in natural products and drug candidates with promising pharmacological properties. However, there remains no general asymmetric methodologies that enable rapid assemble both critical biologically important units into one three-dimensional chiral molecule. Herein, we describe a straightforward relay strategy for the construction of enantioenriched bridged piperidine-γ-butyrolactone skeletons incorporating three skipped stereocenters via asymmetric allylic alkylation and aza-Prins cyclization/lactonization sequences. The excellent enantioselectivity control in asymmetric allylation with the simplest allylic precursor is enabled by the synergistic Cu/Ir-catalyzed protocol; the success of aza-Prins cyclization/lactonization can be attributed to the pivotal role of the ester substituent, which acts as a preferential intramolecular nucleophile to terminate the aza-Prins intermediacy of piperid-4-yl cation species. The resulting chiral piperidine-γ-butyrolactone bridged-heterocyclic products show impressive preliminary biological activities against a panel of cancer cell lines.

Copper/Ruthenium Relay Catalysis for Stereodivergent Access to δ-Hydroxy α-Amino Acids and Small Peptides.

An atom- and step-economical and redox-neutral cascade reaction enabled by asymmetric bimetallic relay catalysis by merging a ruthenium-catalyzed asymmetric borrowing-hydrogen reaction with copper-catalyzed asymmetric Michael addition has been realized. A variety of highly functionalized 2-amino-5-hydroxyvaleric acid esters or peptides bearing 1,4-non-adjacent stereogenic centers have been prepared in high yields with excellent enantio- and diastereoselectivity. Judicious selection and rational modification of the Ru catalysts with careful tuning of the reaction conditions played a pivotal role in stereoselectivity control as well as attenuating undesired α-epimerization, thus enabling a full complement of all four stereoisomers that were otherwise inaccessible in previous work. Concise asymmetric stereodivergent synthesis of the key intermediates for biologically important chiral molecules further showcases the synthetic utility of this methodology.

Halophyte Elymus dahuricus colonization regulates microbial community succession by mediating saline-alkaline and biogenic organic matter in bauxite residue.

Alkalinity regulation and nutrient accumulation are critical factors in the construction of plant and microbial communities and soil formation in bauxite residue, and are extremely important for sustainable vegetation restoration in bauxite residue disposal areas. However, the establishment and succession of microbial communities driven by plant colonization-mediated improvements in the physicochemical properties of bauxite residues remain poorly understood. Thus, in this study, we determined the saline-alkali properties and dissolved organic matter (DOM) components under plant growth conditions and explored the microbial community diversity and structure using Illumina high-throughput sequencing. The planting of Elymus dahuricus (E. dahuricus) in the bauxite residue resulted in a significant decrease in total alkalinity (TA), exchangeable Na, and electrical conductivity (EC) as well as the release of more tryptophan-like protein compounds and low-molecular-weight humic substances associated with biological activities into the bauxite residue substrate. Taxonomical analysis revealed an initial-stage bacterial and fungal community dominated by alkaline-tolerant Actinobacteriota, Firmicutes, and Ascomycota, and an increase in the relative abundances of the phyla Bacteroidota, Cyanobacteria, Chloroflexi, and Gemmatimonadota. The biological activities of phylum Actinobacteriota, Bacteroidota, and Gemmatimonadota were significantly associated with protein-like and UVA-like humic substances. As eutrophic bacteria, Proteobacteria participate in the transformation of humic substances and can not only utilize small molecules of organic matter and convert them into humic substances but also promote the gradual conversion of humic acids into simple molecular compounds. Our results suggest that plant roots secrete organic matter and microbial metabolites as the main biogenic organic matter that participates in the establishment and succession of the microbial community in bauxite residues. Root length affects bacterial and fungal diversity by mediating the production of protein-like substances.

SPIDE: A purely spike-based method for training feedback spiking neural networks.

Spiking neural networks (SNNs) with event-based computation are promising brain-inspired models for energy-efficient applications on neuromorphic hardware. However, most supervised SNN training methods, such as conversion from artificial neural networks or direct training with surrogate gradients, require complex computation rather than spike-based operations of spiking neurons during training. In this paper, we study spike-based implicit differentiation on the equilibrium state (SPIDE) that extends the recently proposed training method, implicit differentiation on the equilibrium state (IDE), for supervised learning with purely spike-based computation, which demonstrates the potential for energy-efficient training of SNNs. Specifically, we introduce ternary spiking neuron couples and prove that implicit differentiation can be solved by spikes based on this design, so the whole training procedure, including both forward and backward passes, is made as event-driven spike computation, and weights are updated locally with two-stage average firing rates. Then we propose to modify the reset membrane potential to reduce the approximation error of spikes. With these key components, we can train SNNs with flexible structures in a small number of time steps and with firing sparsity during training, and the theoretical estimation of energy costs demonstrates the potential for high efficiency. Meanwhile, experiments show that even with these constraints, our trained models can still achieve competitive results on MNIST, CIFAR-10, CIFAR-100, and CIFAR10-DVS.

Efficient and generalizable cross-patient epileptic seizure detection through a spiking neural network.

Introduction: Epilepsy is a global chronic disease that brings pain and inconvenience to patients, and an electroencephalogram (EEG) is the main analytical tool. For clinical aid that can be applied to any patient, an automatic cross-patient epilepsy seizure detection algorithm is of great significance. Spiking neural networks (SNNs) are modeled on biological neurons and are energy-efficient on neuromorphic hardware, which can be expected to better handle brain signals and benefit real-world, low-power applications. However, automatic epilepsy seizure detection rarely considers SNNs. Methods: In this article, we have explored SNNs for cross-patient seizure detection and discovered that SNNs can achieve comparable state-of-the-art performance or a performance that is even better than artificial neural networks (ANNs). We propose an EEG-based spiking neural network (EESNN) with a recurrent spiking convolution structure, which may better take advantage of temporal and biological characteristics in EEG signals. Results: We extensively evaluate the performance of different SNN structures, training methods, and time settings, which builds a solid basis for understanding and evaluation of SNNs in seizure detection. Moreover, we show that our EESNN model can achieve energy reduction by several orders of magnitude compared with ANNs according to the theoretical estimation. Discussion: These results show the potential for building high-performance, low-power neuromorphic systems for seizure detection and also broaden real-world application scenarios of SNNs.

Stereodivergent synthesis of chiral succinimides via Rh-catalyzed asymmetric transfer hydrogenation.

Chiral succinimide moieties are ubiquitous in biologically active natural products and pharmaceuticals. Until today, despite the great interest, little success has been made for stereodivergent synthesis of chiral succinimides. Here, we report a general and efficient method for accessing 3,4-disubstituted succinimides through a dynamic kinetic resolution strategy based on asymmetric transfer hydrogenation. The Rh catalyst system exhibit high activities, enantioselectivities, and diastereoselectivities (up to 2000 TON, up to >99% ee, and up to >99:1 dr). Products with syn- and anti-configuration are obtained separately by control of the reaction conditions. For the N-unprotected substrates, both the enol and the imide group can be reduced by control of reaction time and catalyst loading. In addition, the detailed reaction pathway and origin of stereoselectivity are elucidated by control experiments and theoretical calculations. This study offers a straightforward and stereodivergent approach to the valuable enantioenriched succinimides (all 4 stereoisomers) from cheap chemical feedstocks in a single reaction step.

Deciphering and predicting anammox-based nitrogen removal process under oxytetracycline stress via kinetic modeling and machine learning based on big data analysis.

Anaerobic ammonium oxidation (anammox) is an advanced nitrogen removal process that is widely used in the nitrogen removal of various antibiotic containing wastewaters due to its high efficiency and energy saving characteristics. However, as a widely used antibiotic, the inhibitory effect of oxytetracycline (OTC) on anammox is unclear. In this study, the effect of OTC on the anammox-based nitrogen removal process was revealed by kinetic model and machine learning models. Statistical analysis showed that anammox started to be inhibited when the OTC concentration reached 2 mg/L. The inhibition and recovery periods were simulated under OTC stress. During the inhibition period, the R2 fitted by Exp model was higher, and the simulated maximum nitrogen removal rate (NRR) was between 0.47 and 17.05 kg/(m3·d). During the recovery period, both Boltzmann and Gauss models fit well. In addition, the machine learning model of the artificial neural network predicted the NRR more accurately, indicating that the importance of environmental factors was lower than the effluent parameters. Spearman correlation analysis showed that the NRR was negatively correlated with OTC under both short-term and long-term OTC stress. Furthermore, the hydraulic retention time and water quality parameters played an important role in the short-term and long-term experiment, respectively. Finally, redundancy analysis demonstrated that the abundance of nitrogen functional genes, such as hydrazine dehydrogenase, nitrite/nitric oxide oxidoreductase and hydrazine synthase, was negatively correlated with the amount of OTC, while antibiotic resistance genes showed the opposite trend.

Synergistic Cu/Pd-catalyzed asymmetric allylation: a facile access to α-quaternary cysteine derivatives.

An efficient synthetic methodology to access biologically important and synthetically useful α-quaternary cysteine derivatives via asymmetric catalytic α-allylation of readily available 2-thiazoline-4-carboxylates was successfully developed through a synergistic Cu/Pd catalytic system. A wide array of α-quaternary cysteine derivatives were obtained in moderate to high yields with good to excellent enantioselectivities (45-98% yields and 69->99% ee). Gram-scale asymmetric allylation was performed to obtain high yields maintaining the enantioselectivity. Moreover, some synthetic transformations to access chiral spirocyclic compounds proceeded smoothly, which exhibited the important utility of this methodology.

Stereodivergent Synthesis of α-Quaternary Serine and Cysteine Derivatives Containing Two Contiguous Stereogenic Centers via Synergistic Cu/Ir Catalysis.

A stereodivergent preparation of α-quaternary serine/cysteine derivatives incorporating two adjacent stereogenic centers has been developed through Cu/Ir-catalyzed asymmetric allylation of 2-oxazoline-4-carboxylates and 2-thiazoline-4-carboxylates. Tuning the electronic effect is the key to enhancing the reactivity of 2-oxazoline-4-carboxylates and suppressing the undesired ß-elimination. The salient feature of this protocol is that all four stereoisomers of α-quaternary serine and cysteine derivatives could be achieved from the identical starting materials through pairwise combination of two distinct chiral catalysts.

Pd-Catalyzed Asymmetric Hydroalkylation of 1,3-Dienes: Access to Unnatural α-Amino Acid Derivatives Containing Vicinal Quaternary and Tertiary Stereogenic Centers.

Pd-phosphinooxazoline (Pd-PHOX)-catalyzed asymmetric hydroalkylation of 1,3-dienes with azlactones was successfully developed for the first time, affording various enantioenriched α-quaternary α-amino acid derivatives bearing contiguous quaternary and tertiary stereogenic centers in good yields with exclusive regioselectivity and excellent stereoselective control (up to 92% yield, >20:1 dr, and >99% ee). The scale-up catalytic asymmetric hydroalkylation was performed well without loss of reactivity and stereoselectivities, which exhibited great potential application. The synthetic utility of the current methodology was demonstrated through product transformations to access other biologically important compounds such as chiral ß-amino alcohol and α-quaternary cyclic α-amino acid derivatives.

Identification of candidate genes underlying genic male-sterile msc-1 locus via genome resequencing in Capsicum annuum L.

KEY MESSAGE: Based on genome resequencing, a strong candidate gene Capana02g002096 was identified in this study. Capana02g002096 encodes a homolog of AtDYT1 which is a bHLH transcription factor and involves in the early tapetal development. Genic male-sterile line is an efficient tool for commercial hybrid seed production in pepper; however, so far, only few genes controlling this trait have been cloned. A spontaneous genic male-sterile mutant, msc-1, had been identified and widely used in China, of which the male-sterile trait was proved to be controlled by a single recessive locus. For cloning the gene(s) underlying the msc-1 locus, genome resequencing and comparison analyses were performed between male-sterile and male-fertile lines. According to the genomic variations and genes' annotations, Capana02g002096 was selected as a candidate gene underlying the msc-1 locus. Capana02g002096 encodes a homolog of AtDYT1, which is a bHLH transcription factor and involves in the early tapetal development. Moreover, a 7-bp deletion was identified in the exon of Capana02g002096, which led to a premature stop codon and may cause a loss-of-function mutation. Further genotyping in the 16C1369AB population containing 1110 plants, a F2 population consisting of 510 plants and 46 inbreed lines revealed that the male-sterile phenotype was co-segregated with the 7-bp deletion. Additionally, real-time PCR analysis revealed that Capana02g002096 was an anther-specific gene and repression of the gene's expression through VIGS led to male-sterile phenotype. Therefore, based on the evidence at genetic, genomic, transcriptional and posttranscriptional levels, Capana02g002096 was considered as a strong candidate gene underlying the msc-1 locus in pepper and was renamed Msc-1.

Improving a compact biofilm reactor to realize efficient nitrogen removal performance: step-feed, intermittent aeration, and immobilization technique.

Purifying tank as a compact biofilm reactor has been widely used to remove organic matter in rural sewage, but its potential for nitrogen removal is rare to be discussed. This study developed a lab-scale compact biofilm reactor to realize an efficient nitrogen removal performance by step-feed, intermittent aeration, and immobilization technique. The results show that an efficient simultaneous nitrification and denitrification (SND) process took place by feeding with synthetic wastewater under high C/N ratio of 2 and with real sewage as well, mainly due to the step-feed. The average removal efficiency of total inorganic nitrogen arrived at 72.7 and 63.3% for synthetic wastewater and real sewage, respectively. Besides the step-feed operation, the intermittent aeration was adopted to enhance SND, which allowed hydraulic behavior of compact biofilm reactor following the model of completely stirred tank reactor. The high-throughput sequencing analysis indicates that Sphaerotilus became the dominant genera with relative abundance of 30.29% under high C/N ratio, and the nitrifiers were not greatly inhibited. Moreover, the immobilization technique helped restore microbial activity under low temperature, promoting the satisfactory nitrogen removal performance of recovered microorganism to be rebuilt by feeding nutrient solution. Overall, the long-term SND process and maintaining effective biofilm activity can be established in the compact biofilm reactor through several improving alternatives.

Cobalt-catalyzed (Z)-selective semihydrogenation of alkynes with molecular hydrogen.

Cobalt-catalyzed highly (Z)-selective semihydrogenation of alkynes using molecular H2 was developed using commercially available and cheap cobalt precursors. A variety of (Z)-alkenes were obtained in moderate to excellent selectivities [(Z)-alkene/(E)-alkene/alkane ratio up to >99 : 1 : 1] and it was found that the readily available ethylenediamine ligand is crucial in determining the selectivity.

Selective Rhodium-Catalyzed Hydroformylation of Alkynes to α,ß-Unsaturated Aldehydes with a Tetraphosphoramidite Ligand.

A tetraphosphoramidite ligand was successfully applied to a Rh-catalyzed hydroformylation of various symmetrical and unsymmetrical alkynes to afford corresponding α,ß-unsaturated aldehyde products in good to excellent yields (up to 97% yield). Excellent chemo- and regioselectivities and high activities (up to 20 000 TON) were achieved. The corresponding α,ß-unsaturated aldehyde products can be transformed into many useful and important organic molecules, such as indenamine derivatives and lukianol pyrroles. This great performance makes the hydroformylation of alkynes highly practical with great potential.

The Impact of Interlayer Electronic Coupling on Charge Transport in Organic Semiconductors: A Case Study on Titanylphthalocyanine Single Crystals.

Traditionally, it is believed that three-dimensional transport networks are preferable to those of lower dimensions. We demonstrate that inter-layer electronic couplings may result in a drastic decrease of charge mobilities by utilizing field-effect transistors (FET) based on two phases of titanyl phthalocyanine (TiOPc) crystals. The α-phase crystals with electronic couplings along two dimensions show a maximum mobility up to 26.8 cm(2) V(-1) s(-1) . In sharp contrast, the ß-phase crystals with extra significant inter-layer electronic couplings show a maximum mobility of only 0.1 cm(2) V(-1) s(-1) . Theoretical calculations on the bulk crystals and model slabs reveal that the inter-layer electronic couplings for the ß-phase devices will diminish remarkably the device charge transport abilities owing to the coupling direction perpendicular to the current direction. This work provides new insights into the impact of the dimensionality and directionality of the packing arrangements on charge transport in organic semiconductors.

A toxicology study to evaluate the embryotoxicity of metformin compared with the hypoglycemic drugs, the anticancer drug, the anti-epileptic drug, the antibiotic, and the cyclo-oxygenase (COX)-2 inhibitor.

BACKGROUND: The safe use of medications in pregnant females, their embryos and in offspring is important. The aim of the present study was to evaluate embryotoxicity of metformin (MET) compared with other hypoglycemic drugs (rosiglitazone [RSG] and glimepiride [GLIM]), the anticancer drug 5-fluorouracil (5-FU), the anti-epileptic drug diphenylhydantoin (DPH), the antibiotic penicillin G (PenG), and the cyclo-oxygenase (COX)-2 inhibitor nimesulide (NIM) in an embryonic stem cell test (EST). METHODS: Differences in the expression of developmental marker genes following treatment with the test compounds during the course of differentiation (from embryonic stem cell D3 (D3 cells) to myocardial cells) were determined using real-time quantitative polymerase chain reaction. In these studies, 5-FU was used as a positive control and PenG was used as a negative control. The cytotoxicity of these drugs against D3 cells and 3T3 fibroblasts was determined by the 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. Embryotoxicity was classified according to the prediction model of EST. RESULTS: At concentrations >800 µg/mL MET had a greater cytotoxic effect on D3 cells than 3T3 fibroblasts. At the highest concentration of MET (5 mg/mL), the cell viability of D3 cells and 3T3 fibroblasts was <10% and >30%, respectively. The size of the embryonic body (EB) differentiation area was almost the same over the concentration range 50-200 µg/mL MET, and there was no significant difference in EB differentiation area until a concentration of 400 µg/mL MET. At a concentration of 800 µg/mL MET, the size of EB outgrowth was significantly reduced. The same assays revealed GLIM, RSG, and NIM to be weakly embryotoxic substances. CONCLUSIONS: Based on the EST, MET can be classified as a weakly embryotoxic substance, which suggests that it should be prescribed with caution to pregnant women with gestational diabetes.

Analysis of a complex produced in the Fenton oxidation process.

The absorbances of different concentrations of Fe(2+), Fe(3+) and H2O2 were investigated by UV-visible spectrophotometry without separating the substances. The law of complex formation was studied by considering changes in the UV-vis spectra of mixtures of these three substances. The results show that upon eliminating the influence of the substrate, an iron-based complex was present in the Fenton reaction, which exhibited substantial absorbance from 190 to 500 nm. Therefore, the presence of an unknown complex in the Fenton oxidation process was verified and its concentration varied with a change in the concentration of hydrogen peroxide. This study provides a strong foundation for further studies into the mechanism of traditional hydroxyl radical theory of the Fenton reaction.

Clinical evaluation of SPECT/CT fusion imaging for the diagnosis and determination of localisation of cerebrospinal rhinorrhea.

OBJECTIVE: The objective was to evaluate the clinical value of the single photon emission computerized tomography/computed tomography (SPECT/CT) fusion imaging for the diagnosis and determination of localisation of cerebrospinal rhinorrhea. METHODS: A total of 33 patients with cerebrospinal rhinorrhea were preoperatively injected with (99m)Tc-diethylenetriamine pentaacetic acid (DTPA) through lumbar puncture and then subjected to planar imaging of the cistern 120 min and 180 min after operation. CT and ECT were then performed. Finally, the rhinorrhea ventage and leaking path were confirmed by fusion image analysis. RESULTS: Thirty-one patients who underwent fusion imaging and 30 patients who underwent planar imaging showed abnormal nuclide activity in the cavity between the basis cranii and the nose. After operation, 30 patients who underwent fusion imaging and 18 patients who underwent planar imaging showed complete correction of the leakage. The diagnosis sensitivity and positional accuracy of fusion imaging were 93.9% (31/33) and 90.9% (30/33) at P>.05. The values of planar imaging were 93.5% (29/31) and 79.3% (23/29) at P<.05. CONCLUSION: (99m)Tc-DTPA SPECT/CT fusion imaging of the cistern is an efficient, simple, and accurate method that may be used for diagnosing and determining the localisation of cerebrospinal rhinorrhea ventage and leakage path.

Pharmacokinetics, tissue distribution, excretion, and antiviral activity of pegylated recombinant human consensus interferon-α variant in monkeys, rats and guinea pigs.

The study aims to characterize the pharmacokinetic, tissue distribution, excretion, and antiviral activity properties of a novel pegylated recombinant human consensus interferon-α variant (PEG-IFN-SA) following a single subcutaneous administration to monkeys, rats and guinea pigs. Studies included: (1) pharmacokinetic properties of PEG-IFN-SA and comparison with those of non-pegylated IFN-SA in rhesus monkeys and rats; (2) tissue distribution and urinary, fecal, and biliary excretion patterns of (125)I-PEG-IFN-SA in guinea pigs; and (3) antiviral activity assessment of PEG-IFN-SA in cynomolgus monkeys. The pegylated protein exhibited improved pharmacokinetic properties compared to IFN-SA in both monkeys and rats, with a 12-fold and 15-fold increase in elimination half-life, and a 100-fold and 10-fold decrease in serum clearance, as well as a 2.5-fold and 10-fold increase in the time to reach peak serum concentration, respectively. (125)I-PEG-IFN-SA was found to be distributed to most of the tissues examined and has character of targeting special distribution, and urinary appeared to be a major route for the excretion of PEG-IFN-SA in guinea pigs. Serum sample analysis from PEG-IFN-SA-treated monkeys showed dose-dependent antiviral activity for one week. These findings demonstrate that pegylation of IFN-SA results in more desirable pharmacokinetic properties, enhanced drug exposure and sustained-efficacy of in vivo antiviral action.