Aqua­(2,2′-bipyridine-κ2 N,N′)[2-(3-thien­yl)malonato-κ2 O,O′]zinc(II) dihydrate

In the crystal structure of the title compound, [Zn(C7H4O4S)(C10H8N2)(H2O)]·2H2O, the ZnII ion assumes a trigonal–bipyramidal coordination geometry completed by two N atoms from a 2,2′-bipyridine ligand, two O atoms from a 2-(3-thien­yl)malonate anion and a water mol­ecule. The S atom of the 2-(3-thien­yl)malonate ligand is disordered over two sites with an occupancy ratio of 0.701 (5):0.299 (5). Inter­molecular O—H⋯O hydrogen bonding is present in the crystal structure

3-Carboxy­pyrazino[2,3-f][1,10]phenanthrolin-9-ium-2-carboxyl­ate

In the title zwitterionic compound, C16H8N4O4, the dihedral angle between the carboxyl and carboxyl­ate groups is 72.14 (2)°. In the crystal, mol­ecules are linked by strong inter­molecular O—H⋯O− and N+—H⋯O− hydrogen bonds into double chains extended along [001]. These chains are additionally stabilized by π–π stacking inter­actions between the pyridine and benzene rings [centroid–centroid distance = 3.5542 (8) Å]

Unraveling the Oxidation Mechanism of Formic Acid on Pd(111) Electrode: Implication from pH Effect and H/D Kinetic Isotope Effect

The pH effect and H/D kinetic isotope effect (KIE) of formic acid oxidation reaction (FAOR) on Pd(111) have been systematically investigated by cyclic voltammetry. In addition, the pH effect of acetate adsorption on Pd(111) is also studied to have a deep understanding of the role of adsorbates on Pd(111) during the FAOR process. The results clearly show: (1) In solutions with a fixed concentration of acetic acid, the onset potential of acetate desorption is almost unchanged on the reversible hydrogen electrode (RHE) scale with the increase of pH when the pH is lower than the pKa of acetic acid. However, when the pH is higher than the pKa of acetic acid, the onset potential of acetate desorption shifts positively with a slope of ca. 20 mV per pH unit; (2) In solutions with pH less than 6, the maximum coverage of acetate adsorbed on the Pd(111) electrode is about 0.26 ML; (3) In acidic solutions, FAOR on Pd(111) has obvious pH effect in the potential range of current increasing on SHE scale. After correcting the pHs-induced shift, the onset potential of FAOR shifts negatively by ca. 90 mV per pH unit. However, the pH effect disappears in the potential range after the peak; (4) In alkaline solutions, the onset potential of FAOR is influenced by OHad; (5) The H/D KIE factor of FAOR on Pd(111) is ca. 5 in the pH range of 1–14. Two possible mechanisms trying to explain these results have been proposed. In one, COOadλ– is the active intermediate and the formation of this intermediate is the rate-determining step (RDS), whereas, in the second one, monodentate adsorbed formate (HCOOm) is the active intermediate and its dissociation on the surface is the RDS. The simulated results with both mechanisms are compared with the experimental results and discussed critically.This work was financially supported by the National Natural Science Foundation of China (nos. 22172151 and 22372154). E.H. and J.M.F. acknowledge financial support from Ministerio de Ciencia, Innovación y Universidades (Project PID2022-137350NB-I00). Zhen Wei acknowledges support from the China Scholarship Council (award number 202106340060)

Generation of True Quantum Random Numbers with On-Demand Probability Distributions via Single-Photon Quantum Walks

Random numbers are at the heart of diverse fields, ranging from simulations of stochastic processes to classical and quantum cryptography. The requirement for true randomness in these applications has motivated various proposals for generating random numbers based on the inherent randomness of quantum systems. The generation of true random numbers with arbitrarily defined probability distributions is highly desirable for applications, but it is very challenging. Here we show that single-photon quantum walks can generate multi-bit random numbers with on-demand probability distributions, when the required ``coin'' parameters are found with the gradient descent (GD) algorithm. Our theoretical and experimental results exhibit high fidelity for various selected distributions. This GD-enhanced single-photon system provides a convenient way for building flexible and reliable quantum random number generators. Multi-bit random numbers are a necessary resource for high-dimensional quantum key distribution

Study on the Changes of Cell Wall Polysaccharide and Their Degrading Enzyme Activities during the Development of Lycium barbarum Fruit

To further explore the metabolism of Lycium barbarum polysaccharides, the cell wall microstructure of Lycium barbarum fruits in different growth periods was observed by transmission electron microscopy, and the cell wall polysaccharide content and its degrading enzyme activity were extracted by chemical method. The changes of polysaccharide components in cell wall of Lycium barbarum fruits in different growth periods were analyzed by microcopolymer Raman spectroscopy. The correlation between the content of polysaccharide in cell wall and the activity of degrading enzyme was analyzed. The results showed that the changes of cell wall structure mainly occurred during 28~35 d, with the cell wall becoming significantly thinner, pectin degrading, and the cell wall structure gradually collapsing. Cell wall material (CWM) content increased first and then decreased, and water-soluble pectin (WSP) content increased significantly (P<0.05). Sodium carbonate-soluble pectin (SSP) and Hemicellulose contents increased firstly and then decreased. The activity of polygalacturonase (PG), β-galactosidase (β-Gal) and cellulase (Cx) increased, and the activity of pectin methylesterase (pectin methylesterase) increased. The activity of PME and β-hexosaminidase (β-Hex) decreased at first and then increased. The results of correlation analysis showed that the polysaccharide content of cell wall was significantly correlated with the activity of cell wall degrading enzyme during the growth and development of Lycium barbarum fruit (P<0.05). With the development and maturation of Lycium barbarum fruit, the microstructure of cell wall showed a trend of cell wall collapse and polysaccharide degradation with the change of degrading enzyme activity. The results have theoretical and practical significance to improve the processing quality of Lycium barbarum fruit and formulate suitable storage strategies

From one to many central plans: drug advertising inspections and intra-national protectionism in China

This paper provides the first micro-level evidence for the existence and patterns of intra-national protectionism in China. We demonstrate that drug advertising inspections are used by provincial governments to discriminate against firms from outside the province. We further reveal systematic patterns in the degree of discrimination across firms: those from neighboring areas, those from regions with more economic links to the destination province, those from provinces with stronger presence in the market, and those with political ties to “allied” provincial governments are less likely to be targeted. Our findings highlight the unique politico-economic structure in China and confirm that giving local governments strong incentives to compete with each other may exacerbate the market distortions inherent in a partially reformed economy

Preparation of Iron‐ and Nitrogen‐Codoped Carbon Nanotubes from Waste Plastics Pyrolysis for the Oxygen Reduction Reaction

A novel method to prepare iron and nitrogen co-doped carbon nanotubes (Fe-N-CNT) is proposed, based on catalytic pyrolysis of waste plastics. At first carbon nanotubes are produced from pyrolysis of plastic waste over Fe-Al2O3; then Fe-CNT and melamine are heated together in inert atmosphere. Different co-pyroysis temperatures are tested to optimize the electrocatalyst production. Working at a high doping temperature improved the degree of graphite formation and promoted the conversion of nitrogen to a more stable form. Compared with commercial platinum on carbon, the electrocatalyst obtained from pyrolysis at 850 °C, showed remarkable properties, with onset potential of 0.943 V vs RHE and half-wave potential of 0.811 V vs RHE and even better stability and anti-poisoning. In addition, zinc-air batteries tests were also carried out and the optimized catalyst exhibited high maximum power density

Surface passivation for highly active, selective, stable, and scalable CO2 electroreduction

Electrochemical conversion of CO2 to formic acid using Bismuth catalysts is one the most promising pathways for industrialization. However, it is still difficult to achieve high formic acid production at wide voltage intervals and industrial current densities because the Bi catalysts are often poisoned by oxygenated species. Herein, we report a Bi3S2 nanowire-ascorbic acid hybrid catalyst that simultaneously improves formic acid selectivity, activity, and stability at high applied voltages. Specifically, a more than 95% faraday efficiency was achieved for the formate formation over a wide potential range above 1.0 V and at ampere-level current densities. The observed excellent catalytic performance was attributable to a unique reconstruction mechanism to form more defective sites while the ascorbic acid layer further stabilized the defective sites by trapping the poisoning hydroxyl groups. When used in an all-solid-state reactor system, the newly developed catalyst achieved efficient production of pure formic acid over 120 hours at 50 mA cm–2 (200 mA cell current)

IncHI1 plasmids are epidemic vectors that mediate transmission of tet(X4) in Escherichia coli isolated from China

Introduction: This study aimed to investigate the genetic factors promoting widespread Q6 dissemination of tet(X4) between Escherichia coli and to characterize the genetic contexts of tet(X4). Methods: We isolated E. coli from feces, water, soil and flies collected across a large-scale chicken farm in China in 2020. Antimicrobial susceptibility testing and PFGE typing were used to identify tigecycline resistance and assess clonal relationships among isolates. Plasmids present and genome sequences were analyzed by conjugation, S1 pulsed-field gel electrophoresis (PFGE), plasmid stability testing and whole-genome sequencing. Results: A total of 204 tigecycline-resistant E. coli were isolated from 662 samples. Of these, we identified 165 tet(X4)-carrying E. coli and these strains exhibited a high degree of multidrug resistance. Based on the geographical location distribution of the sampled areas, number of samples in each area and isolation rate of tigecycline-resistant strains and tet(X4)-carrying isolates, 72 tet(X4)-positive isolates were selected for further investigation. Tigecycline resistance was shown to be mobile in 72 isolates and three types of tet(X4)-carrying plasmids were identified, they were IncHI1 (n = 67), IncX1 (n = 3) and pO111-like/IncFIA(HI1) (n = 2). The pO111-like/IncFIA(HI1) is a novel plasmid capable of transferring tet(X4). The transfer efficiency of IncHI1 plasmids was extremely high in most cases and IncHI1 plasmids were stable when transferred into common recipient strains. The genetic structures flanked by IS1, IS26 and ISCR2 containing tet(X4) were complex and varied in different plasmids. Discussion: The widespread dissemination of tigecycline-resistant E. coli is a major threat to public health. This data suggests careful use of tetracycline on farms is important to limit spread of resistance to tigecycline. Multiple mobile elements carrying tet(X4) are in circulation with IncHI1 plasmids the dominant vector in this setting