Experimental investigation on the instability for NiO/β-Ga_(2)O_(3) heterojunction-gate FETs under negative bias stress

A NiO/β-Ga_(2)O_(3) heterojunction-gate field effect transistor(HJ-FET)is fabricated and it_(s)instability mechanisms are exper-imentally investigated under different gate stress voltage(V_(G,s))and stress times(t_(s)).Two different degradation mechanisms of the devices under negative bias stress(NBS)are identified.At low V_(G,s)for a short t_(s),NiO bulk traps trapping/de-trapping elec-trons are responsible for decrease/recovery of the leakage current,respectively.At higher V_(G,s)or long t_(s),the device transfer char-acteristic curves and threshold voltage(V_(TH))are almost permanently negatively shifted.This is because the interface dipoles are almost permanently ionized and neutralize the ionized charges in the space charge region(SCR)across the heterojunction inter-face,resulting in a narrowing SCR.This provides an important theoretical guide to study the reliability of NiO/β-Ga_(2)O_(3) hetero-junction devices in power electronic applications.

Action Mechanism of Antibacterial Hydrolysate from Ruditapes philippinarum

[Objectives] The antibacterial mechanism of protein hydrolysate from Ruditapes philippinarum（ named RPPH） was studied in this article. [Methods]The integrity of bacteria＇s wall and membrane was determined by some traditional ways. [Results]The growth of Staphylococcus aureus and Bacillus subtilis were inhibited by RPPH in the logarithmic phase. The activity of alkaline phosphatase could be detected in the culture solution. The results showed that the protein content and the conductivity of two kinds of bacteria increased with the extension of incubation time. The results of scanning electron microscope revealed that it emerged the phenomenon of agglomeration with the extension of response time in the culture solution of S. aureus,and the cell shape became irregular,a large number of cells stuck together,afterwards intracellular material was released from bacteria,and the boundaries among cells completely disappeared. The cell surface of B. subtilis became rough,the cells began to adhere,intercellular boundaries became blurred,subsequently cells broke,and then intracellular material leaked out after treating for 9 h. The form of B. subtilis could be roughly identified from the remnants of the bacterial debris,and most of the bacteria had been completely cracked and died. Transmission electron microscope results showed that the surface of S. aureus became rough,with uneven distribution of cytoplasm,and darker substances appeared in the middle,followed by leakage of large numbers of intracellular material. Massive cells became dead when treating for 9 h. B. subtilis cells began to shrink,and cytoplasm was distributed unevenly. The significant phenomenon of plasmolysis and rupture of cell wall could be observed. Afterwards,intracellular material spilled out,only the residual and ambiguity nucleoplasm area could be seen,and cells were killed. [Conclusions] Therefore,it was speculated that the RPPH could destroy cell wall and membrane of the two kinds of bacteria,change the permeability of cells membrane,result in the leakage of intracellular substances and enter within the bacterial cells to affect their normal physiological metabolism which led to death.

干旱区盐碱土微生物特征及其影响因素研究进展

干旱区盐碱土是中国重要的土地资源,对其进行改良利用对于推进中国绿色可持续发展具有重要意义,关系着国家粮食安全与生态安全。微生物作为土壤生态系统的重要组成部分,在改良治理盐碱土、提高植物耐盐性等方面发挥着重要作用。开展干旱区盐碱土微生物多样性、群落结构、功能特征及其影响因素的深入研究,可以为干旱区盐碱土的修复和生态重建提供微生物方面的重要参考。本文整理了干旱区盐碱土的概况,分析盐碱土中的微生物多样性、群落结构和生态功能特征,梳理盐碱环境对土壤微生物群落的影响因素,提出干旱区盐碱土微生物研究中存在的问题及今后的发展方向,以期为中国干旱区盐碱土开发利用和微生物资源管理提供参考。

Immune checkpoint inhibitors for the treatment of non-small cell lung cancer brain metastases

Lung cancer has the highest risk of brain metastasis(BM)among all solid carcinomas.The emergence of BM has a significant impact on the selection of oncologic treatment for patients.Immune checkpoint inhibitors(ICIs)are the most promising treatment option for patients without druggable mutations and have been shown to improve survival in patients with non-small cell lung cancer(NSCLC)BM in clinical trials with good safety.Moreover,ICI has shown certain effects in NSCLC BM,and the overall intracranial efficacy is comparable to extracranial efficacy.However,a proportion of patients showed discordant responses in primary and metastatic lesions,suggesting that multiple mechanisms may exist underlying ICI activity in BM.According to studies pertaining to tumor immune microenvironments,ICIs may be capable of provoking immunity in situ.Meanwhile,systematic immune cells activated by ICIs can migrate into the central nervous system and exert antitumor effects.This review summarizes the present evidence for ICI treatment efficacy in NSCLC BM and proposes the possible mechanisms of ICI treatment for NSCLC BMs based on existing evidence.