Influences of annealing temperature on properties of Fe^2+:ZnSe thin films deposited by electron beam evaporation and their applications to Q-switched fiber laser

Fe^2+:ZnSe thin films are prepared on sapphire substrate at room temperature by electron beam evaporation and then annealed in vacuum(about 1×10^-4 Pa)at different temperatures.The influences of thermal annealing on the structural and optical properties of these films such as grain size and optical transmittance are investigated.The x-ray diffraction patterns show that the Fe2+:ZnSe thin film is preferred to be oriented along the(111)plane at different annealing temperatures.After the film is annealed,the full-width-at-half-maximum(FWHM)of the x-ray diffraction peak profile(111)of the film decreases and its crystal quality is improved.Scanning electron microscope images show that the films are more dense after being annealed.Finally,the sample is used as a saturable absorber in ZBLAN fiber laser.The annealed Fe^2+:ZnSe thin films can be used to realize stable Q-switching modulation on ZBLAN fiber laser.The results demonstrate that the Fe2+:ZnSe thin film is a promising material for generating the high-power pulses of mid-infrared Q-switched fiber lasers.

Reduced SARS-CoV-2 infection risk is associated with the use of Seven-Flavor Herb Tea:A multi-center observational study in Shanghai,China

Objective:Omicron,a severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variant,is responsible for numerous infections in China.This study investigates the association between the use of Seven-Flavor Herb Tea(SFHT)and the risk of SARS-CoV-2 infection to develop precise and differentiated strategies for control of the coronavirus disease 2019(COVID-19).Methods:This case-control study was conducted at shelter hospitals and quarantine hotels in China.A total of 5348 laboratory-confirmed COVID-19 patients were enrolled between April 1 and May 31,2022,while 2190 uninfected individuals served as healthy controls.Structured questionnaires were used to collect data on demographics,underlying diseases,vaccination status,and use of SFHT.Patients were propensity-score-matched using 1:1 nearest-neighbor matching of the logit of the propensity score.Subsequently,a conditional logistic regression model was used for data analysis.Results:Overall,7538 eligible subjects were recruited,with an average age of[45.54±16.94]years.The age of COVID-19 patients was significantly higher than that of uninfected individuals([48.25±17.48]years vs[38.92±13.41]years;t=22.437,P<0.001).A total of 2190 COVID-19 cases were matched with uninfected individuals at a 1:1 ratio.The use of SFHT(odds ratio=0.753,95%confidence interval:0.692,0.820)was associated with a lower risk of SARS-CoV-2 infection compared to untreated individuals.Conclusion:Our findings suggest that taking SFHT reduces the risk of SARS-CoV-2 infection.This is a useful study in the larger picture of COVID-19 management,but data from large-sample multi-center,randomized clinical trial are warranted to confirm the finding.

Chimeric protein probes for C5a receptors through fusion of the anaphylatoxin C5a core region with a small-molecule antagonist

Blockade of the interaction of anaphylatoxin C5a with its receptor C5aR1 has been actively studied as a potential treatment for many inflammatory diseases;but current C5a antagonists exhibit inadequate potency and poor species cross-reactivity, and novel biochemical tools are needed to investigate whether the core region of C5a contains important interaction epitopes that can explain these limitations. Herein, we report the development of chimeric protein C5a probes containing both the complete core region of rat or human C5a, and the small-molecule antagonist PMX53-1. These probes were chemically synthesized through hydrazide-based native chemical ligation of a linear peptide hydrazide with the requisite cyclopeptidic antagonist, both of which were made by solid-phase synthesis. Quasi-racemic X-ray crystallography established that attachment of PMX53-1 did not affect the structure of the core region of C5a. Subsequent C5aR1 activity assays demonstrated the probes can provide valuable insights into the development of C5a antagonists;for example, they exhibited significantly better binding affinity and much improved species cross-reactivity than PMX53-1, supporting the notion that the effect of some epitopes outside the C-terminus of C5a should be taken into consideration when designing better C5a antagonists. Surprisingly, the core region of C5a was found to partially agonize C5aR1, suggesting the presence of more than one agonistic interaction in the binding of C5a to C5aR1. This study exemplifies the value of chemical protein synthesis in developing novel receptor probes for drug discovery research.

Discovery, structure,and chemical synthesis of disulfide-rich peptide toxins and their analogs

Recently, medicinal peptide molecules are of great interest to many international pharmaceutical companies, mainly because of their relatively lower research costs, shorter research cycles, and the greater likelihood of being drugs, when compared with traditional small molecules. Due to the great variety in molecule structures and the diverse biological functions, disulfide-rich peptide toxins have become a shining molecular library for the development of polypeptide drugs. In view of the increasing amount of related publications, here we summarize the discovery, structural elucidation and chemical synthesis of disulfide-rich peptide toxins and their analogs.

Enhanced Bombyx genome editing via Cas9 ribonucleoprotein injection

Dear Editor, The clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein (Cas) system has become a popular and powerful method for manipulating genomes with considerably little effort and high efficiency. It allows for the generation of targeted indels, genomic structure variations, and insertion of foreign fragments. However, increasing concerns have been raised about possible off-target effects.