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Surface compositional disorder were discovered in ZnWO4 nanocrystals prepared by solvothermal method.
•An efficient size-controlled preparation method was developed for ...ZnWO4.•Size-induced surface disorder was prevailed in ZnWO4 nanomaterials.•The composition of surface disordered layer was different from bulk phase.•Effects of surface composition disorder on the photoluminescence and photocatalysis were discussed.
Present work focuses on the surface composition disorder, its origin and relevance to photoluminescent and photocatalytic properties of ZnWO4 nanocrystals. ZnWO4 nanoparticles were synthesized under solvothermal conditions, in which formic acid was employed for both the nonstoichiometry and kinetic size control. Nonstoichiometry ranging from 1.05 to 1.18 was originated from the surface Zn-rich disorder layer, as reflected by an excess of cation Zn2+ in the X-ray photoelectron spectroscopy and a new Raman vibration mode at about 930cm−1 and HR-TEM images. Surface Zn-rich disorder layer has shown a great impact on the structure and properties, including lattice expansion, band-gap narrowing, luminescence enhancement, as well as photocatalytic weakening effect. The investigation on surface composition disorder of multi-component oxides is helpful to deeply understand their formation process and further to find a new functionality optimizing approach.
This paper presents an analysis on the appearance of limit cycles in planar Filippov system with two linear subsystems separated by a straight line. Under the restriction that the orbits with points ...in the sliding and escaping regions are not considered, we provide firstly a topologically equivalent canonical form of saddle-focus dynamic with five parameters by using some convenient transformations of variables and parameters. Then, based on a very available fourth-order series expansion of the return map near an invisible parabolic type tangency point, we show that three crossing limit cycles surrounding the sliding set can be bifurcated from generic codimension-three singularities of planar discontinuous saddle-focus system. Our work improves and extends some existing results of other researchers.
With the deepening of population aging, the expenditure of basic endowment insurance in China is increasing. The urban employees' basic endowment insurance(UEBEI) system for is an important part of ...China's basic social endowment insurance system, which is the most important institutional guarantee for the basic needs of employees after retirement. It not only relates to the living standards of retired employees but also relates to the stability of the whole society. Especially considering the acceleration of urbanization process, the financial sustainability of the basic endowment insurance for employees is of great significance for safeguarding the pension rights of retired employees and realizing the normal operation of the whole system, and the operation efficiency of urban employees' basic endowment insurance(UEBEI) fund inevitably becomes the focus of increasing attention. Based on the panel data of 31 provinces in China from 2016 to 2020, this paper established a three-stage DEA-SFA model, and compared the differences of comprehensive technical efficiency, pure technical efficiency and scale efficiency with radar chart, aiming to explore the operating efficiency of the UEBEI in China and how environmental factors affect it. The empirical results show that at present, the overall level of the expenditure efficiency of the UEBEI fund for urban workers is not high, and all provinces have not reached the efficiency frontier level, and there is still a certain space for efficiency improvement. Fiscal autonomy and elderly dependency ratio are negatively correlated with fund expenditure efficiency, while urbanization level and marketization level are positively correlated with fund expenditure efficiency. The regional difference of fund operation efficiency is significant, from high to low, it is East China, Central China and West China. Reasonable control of environmental variables and narrowing of regional economic development and fund expenditure efficiency differences can provide some enlightenment for better realization of common prosperity.
Cadmium, Cu, Pb and Zn concentrations and distribution in soil, wheat, and the potential for human heavy metal accumulation near a Pb smelting affected area were investigated. Farm land soil, wheat ...grain and scalp hair samples were collected from three villages (named QD, GF and BS) with increasing distance from a large Pb smelter in China. Soil Cd and Pb concentrations exceeded national standards 46–100% of the time, depending on location. Soil and wheat grain Cd, Cu, Pb and Zn concentrations increased as distance to the smelter decreased. Similarly, greater Cd, Cu and Pb concentrations were present in human scalp hair for those residents living closest to the smelter. Decreasing trends existed for hair-to-wheat grain ratios for Cd and Pb as distance to the smelter increased. Results suggest that as distance to the smelter decreases, human heavy metal absorption via the consumption of metal-contaminated food products (e.g., wheat) increases.
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•Greater Cd, Pb and Cu scalp hair concentrations in villagers near the lead smelter.•Accumulation of Pb and Cd negatively affects human Zn absorption.•Human metal accumulation dominated by particulate inhalation/ingestion near smelter.•Human metal accumulation dominated by food consumption further from smelter.
Lead smelting resulted in elevated Cd, Cu and Pb concentrations in scalp hairs of residents living closer to the smelter, while inhibited Zn accumulation in hair.
In this letter, a computationally efficient subspace algorithm is developed for two-dimensional (2-D) direction-of-arrival (DOA) estimation with L-shaped array structured by two uniform linear arrays ...(ULAs). The proposed method requires neither constructing the correlation matrix of the received data nor performing the singular value decomposition (SVD) of the correlation matrix. The problem is solved by dealing with three vectors composed of the first column, the first row and diagonal entries of the correlation matrix, which reduces the computational burden. Simultaneously, the proposed method utilizes the conjugate symmetry to enlarge the effective array aperture, which improves the estimation precision. The simulation results are presented to validate the effectiveness of the proposed algorithm.
Abstract
MicroRNAs (miRNAs) are noncoding RNAs with 18–26 nucleotides; they pair with target mRNAs to regulate gene expression and produce significant changes in various physiological and ...pathological processes. In recent years, the interaction between miRNAs and their target genes has become one of the mainstream directions for drug development. As a large-scale biological database that mainly provides miRNA–target interactions (MTIs) verified by biological experiments, miRTarBase has undergone five revisions and enhancements. The database has accumulated >2 200 449 verified MTIs from 13 389 manually curated articles and CLIP-seq data. An optimized scoring system is adopted to enhance this update’s critical recognition of MTI-related articles and corresponding disease information. In addition, single-nucleotide polymorphisms and disease-related variants related to the binding efficiency of miRNA and target were characterized in miRNAs and gene 3′ untranslated regions. miRNA expression profiles across extracellular vesicles, blood and different tissues, including exosomal miRNAs and tissue-specific miRNAs, were integrated to explore miRNA functions and biomarkers. For the user interface, we have classified attributes, including RNA expression, specific interaction, protein expression and biological function, for various validation experiments related to the role of miRNA. We also used seed sequence information to evaluate the binding sites of miRNA. In summary, these enhancements render miRTarBase as one of the most research-amicable MTI databases that contain comprehensive and experimentally verified annotations. The newly updated version of miRTarBase is now available at https://miRTarBase.cuhk.edu.cn/.
School teachers represent an occupational group among which there appears to be a high prevalence of neck and/or shoulder pain (NSP) and low back pain (LBP). Epidemiological data on NSP and LBP in ...Chinese teachers are limited. The aim of this study was to investigate the prevalence of and risk factors for NSP and LBP among primary, secondary and high school teachers.
In a cross-sectional study of teachers from 7 schools, information on participant demographics, work characteristics, occupational factors and musculoskeletal symptoms and pain were collected.
Among 893 teachers, the prevalence of NSP and LBP was 48.7% and 45.6% respectively. There was significant association between the level and prevalence of NSP and LBP among teachers in different schools. The prevalence of NSP among female teachers was much higher than that for males. Self-reported NSP was associated with physical exercise (OR 0.55, 95% CI 0.35 to 0.86), prolonged standing (1.74, 1.03 to 2.95), sitting (1.76, 1.23 to 2.52) and static posture (2.25, 1.56 to 3.24), and uncomfortable back support (1.77, 1.23 to 2.55). LBP was more consistently associated with twisting posture (1.93, 1.30 to 2.87), uncomfortable back support (1.62, 1.13 to 2.32) and prolonged sitting (1.42, 1.00 to 2.02) and static posture (1.60, 1.11 to 2.31).
NSP and LBP are common among teachers. There were strong associations with different individual, ergonomic, and occupational factors.
Proper disposal of spent lithium-ion batteries is beneficial for the resource recycling and pollution elimination. Full liberation of electrode materials, including the liberation between electrode ...material and current collector (copper/aluminum foils) and the liberation among electrode material particles, is the pivotal precondition for improving the recovery efficiency of electrode materials. In this article, authors attempt to carry out a summary of current technologies used in the liberation of electrode materials derived from spent lithium-ion batteries. However, specialized studies about the liberation of electrode materials are insufficient at present. This research clearly shows that: (1) Organic binder must be removed so as to improve the liberation and metallurgy efficiency of electrode materials; (2) A collaboration of varied technologies is the necessary process to achieve high liberation efficiency between electrode materials and copper/aluminum foils; (3) Pyrolysis may be a recommended technology for removal of organic binder because part of pyrolysis products can be recovered. Finally, an alternative recycling flowchart of spent LIBs is proposed.
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•Review different technologies for the liberation of electrode materials from foils•Identify the necessity of removing organic binders for recycling of spent LIBs•Summary main problems in the recycling process of spent LIBs•Suggest alternative flowchart for the recovery of electrode materials
Abstract
Nanomedicine holds promise to enhance cancer immunotherapy; however, its potential to elicit highly specific anti-tumor immunity without compromising immune tolerance has yet to be fully ...unlocked. This study develops deep-tissue activatable cancer sono-immunotherapy based on the discovery of a semiconducting polymer that generates sonodynamic singlet oxygen (
1
O
2
) substantially higher than other sonosensitizers. Conjugation of two immunomodulators via
1
O
2
-cleavable linkers onto this polymer affords semiconducting polymer immunomodulatory nanoparticles (SPINs) whose immunotherapeutic actions are largely inhibited. Under ultrasound irradiation, SPINs generate
1
O
2
not only to directly debulk tumors and reprogram tumor microenvironment to enhance tumor immunogenicity, but also to remotely release the immunomodulators specifically at tumor site. Such a precision sono-immunotherapy eliminates tumors and prevents relapse in pancreatic mouse tumor model. SPINs show effective antitumor efficacy even in a rabbit tumor model. Moreover, the sonodynamic activation of SPINs confines immunotherapeutic action primarily to tumors, reducing the sign of immune-related adverse events.
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