Regulation of excitation energy transfer in Sb-alloyed Cs_(4)MnBi_(2)Cl_(12) perovskites for efficient CO_(2) photoreduction to CO and water oxidation toward H_(2)O_(2)

Lead(Pb)-free halide perovskites have recently attracted increasing attention as potential catalysts for CO_(2) photoreduction to CO due to their potential to capture solar energy and drive catalytic reaction.However,issues of the poor charge transfer still remain one of the main obstacles limiting their performance due to the overwhelming radiative and nonradiative charge-carrier recombination losses.Herein,Pb-free Sb-alloyed all-inorganic quadruple perovskite Cs_(4)Mn(Bi_(1-x)Sb_(x))_(2)Cl_(12)(0≤x≤1)is synthesized as efficient photocatalyst.By Sb alloying,the undesired relaxation of photogenerated electrons from conduction band to emission centers of[MnCl6]^(4-)is greatly suppressed,resulting in a weakened PL emission and enhanced charge transfer for photocatalyst.The ensuing Cs_(4)Mn(Bi_(1-x)Sb_(x))_(2)Cl_(12) photocatalyst accomplishes efficient conversion of CO_(2)into CO,accompanied by a surprising production of H_(2)O_(2),a high valueadded product associated with water oxidation.By optimizing Sb^(3+) concentration,a high CO evolution rate of 35.1μmol g^(-1)h^(-1)is achieved,superior to most other Pb and Pb-free halide perovskites.Our findings provide new insights into the mixed-cation alloying strategies for improved photocatalytic performance of Pb-free perovskites and shed light on the rational design of robust band structure toward efficient energy transfer.

Damage of hippocampal neurons in rats with chronic alcoholism

Chronic alcoholism can damage the cytoskeleton and aggravate neurological deficits. However, the effect of chronic alcoholism on hippocampal neurons remains unclear. In this study, a model of chronic alcoholism was established in rats that were fed with 6% alcohol for 42 days. Endogenous hydrogen sulfide content and cystathionine-beta-synthase activity in the hippocampus of rats with chronic alcoholism were significantly increased, while F-actin expression was decreased. Hippocampal neurons in rats with chronic alcoholism appeared to have a fuzzy nuclear mem- brane, mitochondrial edema, and ruptured mitochondrial crista. These findings suggest that chronic alcoholism can cause learning and memory decline in rats, which may be associated with the hydrogen sulfide/cystathionine-beta-synthase system, mitochondrial damage and reduced expression of F-actin.

Histone acetylation of the htr3a gene in the prefrontal cortex of Wistar rats regulates ethanol-seeking behavior

Previous reports showed that decreased histone deacetylase activity significantly potentiated the rewarding effects of psychostimulants, and that encoding of the 5-HT3 receptor by the htr3a gene was related to ethanol-seeking behavior. However, the effects of a histone deacetylase inhibitor on ethanol-seeking behavior and epigenetic regulation of htr3a mRNA expression after chronic ethanol exposure are not fully understood. Using quantitative reverse transcription-polymerase chain reaction and chromatin immunoprecipitation analysis, we investigated the effects of chronic ethanol exposure and its interaction with a histone deacetylase inhibitor on histone-acetylation-mediated changes in htr3a mRNA expression in the htr3a promoter region. The conditioned place preference procedure was used to evaluate ethanol-seeking behavior. Chronic exposure to ethanol effectively elicited place conditioning. In the prefrontal cortex, the acetylation of H3K9 and htr3a mRNA expression in the htr3a promoter region were significantly higher in the ethanol group than in the saline group. The histone deacetylase inhibitor sodium butyrate potentiated the effects of ethanol on htr3a mRNA expression and enhanced ethanol-induced conditioned place preferences. These results suggest that ethanol upregulates htr3a levels through mechanisms involving H3K9 acetylation, and that histone acetylation may be a therapeutic target for treating ethanol abuse.

Bismuth doped lead-free two-dimensional tin based halide perovskite single crystals

Heterovalent-metal doping is an efficient tool to tune the optoelectronic properties of the famous halide perovskites.Previous studies have focused on the heterovalent-doping in three-dimensional(3D) halide perovskites.However, there is a lack of such doping in two-dimensional perovskites which possess unique optoelectronic properties and improved chemical stability as compared to 3D analogues.Here, we present successful doping of Bismuth into the lattice of lead-free, two-dimensional perovskite PEA2SnBr4 single crystals.Structural characterizations demonstrate that the doped crystals possess identical crystal structure and layered morphology with the pristine one.Intriguingly, we find the PL peak and spectral shape can be tailored by tuning the concentration of Bi dopants.Femtosecond transient absorption spectroscopy is performed to understand the underlying mechanism related to tunable PL behaviors, and a clear picture of the Bismuth-doping impact is provided.

Expert consensus on the prevention and treatment of substance use and addictive behaviour-related disorders during the COVID-19 pandemic

In early 2020,the COVID-19 outbreak complicated the diagnosis,treatm ent and rehabilitation of patients with substance use disorders and increased the risks of substance abuse and addictive behaviours,such as online gaming disorders,in the general public.Substance use disorder is a chronic recurrent brain disease characterised by strong cravings,high recurrence rates,and a high proportion of comorbidity of mental and physical disorders.1 Therefore,regular long-term therapeutic interventions are critical to preventing dm g relapses while maintaining withdrawal.

A new treatment for cognitive disorders related to in utero exposure to alcohol

Maternal alcohol consumption during pregnancy has detrimental effects on fetal central nervous system development. Maternal alcohol consumption prior to and during pregnancy significantly affects cognitive functions in offspring, which may be related to changes in cyclin-dependent kinase 5 because it is associated with modulation of synaptic plasticity and impaired learning and memory, in this study, we examined adult offspring in a materna~ alcohol consumption model in rats. Y-maze test results showed that in utero exposure to alcohol impairs learning and memory capacities. Cyclin-dependent kinase 5 mRNA and protein expressions in the hippocampus of the offspring were significantly elevated, as assayed by quantitative real-time PCR and reverse transcription-PCR, immunofluorescence, and immuno-precipitation. Our experimental findings strongly suggest that altered cydin-dependent kinase 5 may mediate impaired learning and memory in adult rats that were exposed to alcohol by maternal consumption while in utero.

Modeling and Optimization of Bandwidth Supply Performance for Cloud-Assisted Video Systems under Flash Crowd

The large-scale and sudden video content access such as flash crowds results in huge bandwidth demand,which severely influence user quality of experience and quality of service of video systems.In this paper,we firstly discuss the main reason of generation of flash crowds for video streaming services and analyze key factor for balance recovery between supply and demand of upload bandwidth.We construct two models:bandwidth supply capacity model of video systems and bandwidth demand model of users,which measures usage amount of bandwidth of the cloud.Based on the built models,we further employ a community-based cooperative caching strategy of video resources to promote supply capacity of upload bandwidth of video systems.Extensive tests show how the proposed cooperative caching strategy achieves much better performance results in comparison with original solution.

二维sp^(2)碳共价有机框架及高效光催化制氢

本文设计合成了两种具有不同连接方式(亚胺键和sp^(2)-C-CN键)的三嗪基共价有机框架(COFs)材料.连接单元的微小变化导致可见光驱动制氢性能的巨大差异.具有sp^(2)碳连接方式的全π共轭二维COFs在450 nm波长处表现出13.48%的外量子效率,优于已报道的COFs光催化剂.而亚胺键的二维COFs几乎没有光活性.借助光电化学研究和量子化学计算进一步研究了二维COFs的催化机理,为太阳能转化高性能有机光催化剂的制备提供了新的见解.

Phylogeny and species differentiation of Mollitrichosiphum spp. （Aphididae, Greenideinae） based on mitochondrial CO1 and Cyt b genes

Phylogenetic analyses based on mitochondrial genes were conducted to reconstruct species relationships within the aphid genus MoUitrichosiphum （Aphididae, Greenideinae）. MP and Bayesian analysis results using COI and Cyt b datasets, and combined MP, ML and Bayesian analysis of both were consistent with a morphologically supported monophyly. Subdivision of the genus into two subgenera was strongly supported. Samples of each included species form monophyletic clade, respectively; and the result implied the valid status of related species in this genus. These results suggest some surprising hypotheses regarding the phylogeography of the genus： the uplift of the Tibetan Plateau, reorganization of major fiver catchments and the isolation of Hainan Island were probably important factors contributing to the diversification of species in this genus .

Lead-free rare-earth double perovskite Cs_(2)AgIn_(1−γ−x)Bi_(x)La_(γ)Cl_(6)nanocrystals with highly efficient warm-white emission

Lead-free double perovskite nanocrystals(NCs),such as Cs2AgInCl6,have attracted considerable attention as stable and non-toxic alternatives to lead-based perovskites.However,the low photoluminescence(PL)intensity of pristine Cs_(2)AgInCl_(6)limits its practical applications.In this study,a series of Cs_(2)AgIn_(1−γ−x)Bi_(x)La_(γ)Cl_(6)NCs were synthesized to break the parity-forbidden transition and modify the associated optical functionalities.A broadband bright warm-white emission in the visible region was achieved,with an excellent PL quantum yield of 60%.The dynamic mechanism,involving ultrafast transient absorption,suggests that high-efficiency PL is induced by triplet self-trapping exciton emission.The incorporation of La^(3+)-Bi^(3)+facilitated the singlet–triplet transition by increasing the lifetime and quickening the intersystem crossing process.This finding provides a reliable method for optimizing the optical properties of emerging lead-free halide perovskite NCs.

Tuning Exciton Recombination Pathways in Inorganic Bismuth-Based Perovskite for Broadband Emission

Single-component emitters with broadband emission are attractive but challenging for illumination and display applications.The two-dimensional organic-inorganic hybrid perovskites have exhibited outstanding broad emission property due to low electronic dimensionality and strong exciton-phonon coupling.However,few layered all-inorganic lead-free perovskites with broadband emission have been explored,and the explicit mechanism of exciton recombination in them also needs in-depth understanding.Herein,the inorganic bismuth-based perovskite Cs3Bi2Br9 achieves the stable broadband emission under ambient temperature and pressure by tuning the exciton recombination pathways via antimony(Sb)doping,and the photoluminescence quantum yield(PLQY)realizes an enhancement from 2.9%to 15.9%.The photoluminescence excitation(PLE)spectra indicate that the doped Sb introduces newly extrinsic self-trapped states.The incorporation of Sb promotes the transfer of free excitons(FEs)to extrinsic self-trapped excitons(STEs)observed from Sb content-dependent steady-state PL spectra and,meanwhile,reduces the nonradiative recombination of the generated extrinsic STEs,which are primarily responsible for the remarkably enhanced broad emission.Furthermore,femtosecond transient absorption results elucidate a clear exciton dynamics,in which the transition from FEs to STEs might arise through the gradient energy levels,and finally extrinsic STEs at various energy states contribute to the broadband emission.