V形槽静电超声传感器静电场不均匀性研究

分析V形槽静电超声传感器微气隙结构研究静电场不均匀性,用解拉普拉斯方程的方法解的单个V形槽面电荷密度.通过建立π/4角两平板电容器模型,提出V形槽静电传感器电容值的定量计算方法,得到与试验相接近的结果.     

多功能结构在固体火箭上的应用分析

为实现固体火箭轻质化设计,采用传统机械结构优化的方法能力十分有限。多功能结构优化设计方法,由于采用机、电、热一体化的系统工程级设计思路,为提升火箭整体性能开辟了一个全新的方向。介绍多功能结构设计方法及思路,结合一种新型箭载记录设备原型样机的研制,对多功能结构在固体火箭领域应用的前景进行深入探讨。     

水射流清洗技术应用现状及其前景

近年来,水射流清洗技术已在众多领域得到广泛应用,并取得了显著成效。分析了水射流清洗的原理、特点、设备现状和应用实例,并对其发展前景作了展望。     

Hydrothermally stable mesoporous aluminosilicates with moderate acidity via degradation-assembly process and improved catalytic properties

Mesoporous aluminosilicates with hydrothermal stability and moderate acidity are synthesized via assembly of microporous zeolite precursors obtained by the degradation of zeolite NaY, denoted as “degradation-assembly” (DA) technique. By controlling the degradation degree of matrix NaY, precursors with larger spatial volume and stronger rigidity will be obtained. The characterization results showed that the walls of the mesophase in MDA (mesoporous aluminosilicate obtained by “DA” method) composed of the preformed zeolite Y building units and the moderate acidity was inherited from the introduced precursors. It was suggested that the more mature assembly units accounted for the increased acidity of MDA with more Al species retained in the framework of mesophases. The resulting aluminosilicates with simultaneously moderate acidity and hydrothermal stability showed superior catalytic properties when used in heavy oil catalytic cracking catalysts.     

Sterols from Mytilidae Show Anti-Aging and Neuroprotective Effects via Anti-Oxidative Activity

For screening anti-aging samples from marine natural products, K6001 yeast strain was employed as a bioassay system. The active mussel extract was separated to give an active sterol fraction (SF). SF was further purified, and four sterol compounds were obtained. Their structures were determined to be cholesterol (CHOL), brassicasterol, crinosterol, and 24-methylenecholesterol. All compounds showed similar anti-aging activity. To understand the action mechanism involved, anti-oxidative experiments, reactive oxygen species (ROS) assays, and malondialdehyde (MDA) tests were performed on the most abundant compound, CHOL. Results indicated that treatment with CHOL increases the survival rate of yeast under oxidative stress and decreases ROS and MDA levels. In addition, mutations of uth1, skn7, sod1, and sod2, which feature a K6001 background, were employed and the lifespans of the mutations were not affected by CHOL. These results demonstrate that CHOL exerts anti-aging effects via anti-oxidative stress. Based on the connection between neuroprotection and anti-aging, neuroprotective experiments were performed in PC12 cells. Paraquat was used to induce oxidative stress and the results showed that the CHOL and SF protect the PC12 cells from the injury induced by paraquat. In addition, these substance exhibited nerve growth factor (NGF) mimic activities again confirmed their neuroprotective function.     

Genomic and metabolomic analysis of Bacillus licheniformis with enhanced poly-γ-glutamic acid production through atmospheric and room temperature plasma mutagenesis

Poly-γ-glutamic acid is an extracellular polymeric substance with various applications owing to its valuable properties of biodegradability, flocculating activity, water solubility, and nontoxicity. However, the ability of natural strains to produce poly-γ-glutamic acid is low. Atmospheric and room temperature plasma was applied in this study to conduct mutation breeding of Bacillus licheniformis CGMCC 2876, and a mutant strain M32 with an 11% increase in poly-γ-glutamic acid was obtained. Genome resequencing analysis identified 7 nonsynonymous mutations of ppsC encoding lipopeptide synthetase associated with poly-γ-glutamic acid metabolic pathways. From molecular docking, more binding sites and higher binding energy were speculated between the mutated plipastatin synthase subunit C and glutamate, which might contribute to the higher poly-γ-glutamic acid production. Moreover, the metabolic mechanism analysis revealed that the upregulated amino acids of M32 provided substrates for glutamate and promoted the conversion between L- and D-glutamate acids. In addition, the glycolytic pathway is enhanced, leading to a better capacity for using glucose. The maximum poly-γ-glutamic acid yield of 14.08 g·L^–1 was finally reached with 30 g·L^–1 glutamate.     

高层建筑施工中大体积混凝土的裂缝控制

高层混凝土建筑的裂缝控制应该防患于未然,尽量预防有害裂缝,科学地将其有害程度控制在规范允许的范围内。只要使设计与施工能紧密结合,将裂缝控制在无害范围内是完全可以做到的。本文探讨了高层建筑施工中大体积混凝土的裂缝控制措施。     

镀锌产品锌层质量和厚度的测定方法

介绍并对比镀锌板、带、丝、棒、管以及涂塑产品锌层质量和厚度在测定中执行的不同标准、计算公式、取样量和对天平精度的要求;指出测定锌层质量和厚度的方法主要有重量法、电磁测量法、金相测量法、电化学溶解法。其中重量法由于简单易操作,不仅在国内外广泛应用,而且在仲裁试验时也常用此法。     

提高住宅生命周期的技术手段分析

首先给出住宅生命周期的概念和内涵,然后通过对欧盟、北美、东亚部分典型国家住宅生命周期的调查和我国部分大型城市的住宅生命周期进行比较,分析我国住宅生命周期偏短的原因,并结合当前实际情况提出参考意见,重点从结构设计(规范的修订、结构的耐久性设计)方面进行技术分析。