过流/过热保护用高分子热敏电阻

在介绍高分子热敏电阻(PPTC)性质、组成及工作原理的基础上,分析了PPTC较其他几种电流保护装置的优势,并指出了PPTC的应用现状及发展方向。     

硅二极管内层聚酰亚胺保护胶的研制

由聚硅氧烷二胺、芳香族二胺、芳香族二酐溶液缩聚合成的含硅聚酰亚胺应用于硅二极管内层绝缘保护,显示出良好的应用前景。     

Protection Glass Eyewear Against a YAG Laser Based on a Bandpass Absorption Filter

In this article, copper zinc phosphate glass doped with 5 % barium oxide has an amazing optical property due to its application as bandpass filters. Typically, the glass conventional casting with chemical composition 42P₂O₅–(14- x)Na₂O–39ZnO–5BaO–xCu₂O where (x = 2, 4, 6, 8 and 10) was formed. The density was measured using the conventional Archimedes method and the molar volume was calculated. The change of glass structure was investigated using X-ray diffraction analysis (XRD). Distinctly, the results revealed that no crystal growth in all glass systems was observed. The density of glass samples was increased whereas the molar volume was decreased with increasing copper content. The absorption, transmission and reflection were measured and some other optical properties were calculated like UV cut-off, and IR cut-off. For instance, the visible cut-off started from 462 to 532 nm while the IR bonds were initiated at 630 to 1200 nm with 6 to 10 % Cu₂O concentration.     

火箭推进剂防护材料研究

火箭推进剂由于其特殊作用、使用条件和安全要求,需采用多种防护手段对其防护,尤其是防止对人体呼吸器官的损伤。研究了推进剂防护材料和装填方法,结果表明新研制的催化剂对氮氧化物和偏二甲肼均有较好的防护性能。在氮氧化物质量浓度为3.76mg/L时,防护时间>130min;在偏二甲肼质量浓度为4.55mg/L时,防护时间>160min。     

Yttrium Silicate Coatings for Oxidation Protection of Carbon–Silicon Carbide Composites

Yttrium silicate (Y₂SiO₅) coatings complement SiC coatings for protecting ceramic multilayer composite materials based on carbon-fiber-reinforced SiC composites (C-SiC). Thick (100 μm), dense Y₂SiO₅ coatings were prepared by dip coating, using concentrated aqueous slips. The resulting phases were studied by taking into account the simultaneous presence of oxide and non-oxide materials, which affected the chemical stability of the coatings. Thick, mechanically stable coatings were obtained by sintering in carbon crucibles and a SiC bed in an argon-flow furnace. Pure Y₂SiO₅ coatings completely separated from the SiC substrates. A high percentage of Y₂Si₂O₇ was necessary to fit the thermal expansion coefficients and ensure the stability of the coatings. Oxidation resistance of the coated substrates was investigated by isothermal and stepwise oxidation tests.     

绿脓杆菌外膜蛋白对感染的保护作用

目的 寻找一种防治绿脓杆菌感染的有效方法。方法 用绿脓杆菌外膜蛋白免疫的兔抗血清对4种不同血清型的菌株和1株临床绿脓杆菌进行体内外交叉保护性试验。结果 家兔免疫1周后即产生抗体,并逐渐升高,至第6周抗体滴度达到1:163 840,并维持高水平;抗血清能与4种不同血清型菌株和1株临床菌株产生直接凝集反应。第8周的血清(1:8以上)与其外胰蛋白的ELISA抗体效价相近,小鼠的半保护剂量均在0.05～0.11ml之间。结论 外膜蛋白疫苗具有较强的抗原性,而且具有良好的交叉保护作用。     

关于现代建筑物防雷保护问题浅析

随着建筑智能化程度的提高,对防雷技术的要求也越来越高。防雷措施如何更好地服务于人民的生活,是本文重点探讨的问题。     

Protection of Nylon 6. 6 Against Heat Degradation

Thermal degradation of nylon 6. 6 by hot air results in a fall of tensile strength accompanied by yellowing of the fibre. This change is perceptible at the temperatures commonly used in setting polyamide fabrics and in dyeing them by thermofixation methods. The importance of the thiourea treatment, discussed in the present paper, lies in the fact that it raises by about 30 deg C the temperature at which thermal degradation of nylon 6. 6 begins. This treatment provides complete protection of the fibre, permits more rapid treatment at a higher temperature, leading to better productivity, and offers wider possibilities for dyeing by thermofixation.     

Design and Fabrication of Protection Window Against YAG Laser

Window protection glass against a YAG laser based on a bandpass absorption filter was fabricated from bismuth oxide doped copper phosphate glass with series of xBi₂O₃-(40-x) ZnO-10Na₂O-6Cu₂O-44P₂O₅ in molar ratio with x=0, 5 and 10 and were prepared by using a conventional glass casting and quenching technique. The density was measured by the conventional Archimedes method and the molar volume was calculated. Bismuth oxide is a heavy element; by increasing the doping in a glass composition it can cause an unusual phenomenon between the density and molar volume, they can have the same trend. The glass was investigated by using the XRD technique, which proved the systems are completely in the glass state. Optical spectroscopic analysis of the glass filter from the transmittance data showed the UV and the IR cut-off bands to the bandpass filter, which confirmed the band absorption in the IR cut-off included the Nd:YAG laser wavelength, which can be used for a glass laser safety window.     

基于纵联保护原理的直流输电系统接地极不平衡保护

直流输电系统接地极故障保护配置的不平衡保护动作触发条件和保护策略都存在一定的缺陷。针对存在的问题,介绍单极大地回线运行方式下接地极引线故障的运行实例。然后借鉴输电线路的纵联保护原理,在原保护基础上提出了基于纵联保护原理的不平衡保护改进方案。应用结果表明:改进的方案可根据接地极引线发生接地故障和断线故障时各电流值的变化规律来判断故障类型。     

碳化硅基材表面涂层方法综述

碳化硅基陶瓷是应用于高温工作环境下的理想材料，但其高温氧化影响了它的进一步应用。本文简要叙述了碳化硅材料的氧化机理，重点总结了在其表面涂层的各种方法。同时也对目前所做工作的不足提出了见解。     

Silicon Nitride Based Ceramic Nanocomposites

Nanocomposites (Si₃N₄/SiC) were studied by combined high-resolution transmission electron microscopy and electron energy-loss spectroscopic imaging (ESI) techniques. In ESI micrographs three types of crystalline grains were distinguished: Si₃N₄ matrix grains (0.5 μΩ), nanosized SiC particles (<100 nm) embedded in the Si₃N₄, and large SiC particles (100–200 nm) at grain boundary regions (intergranular particles). Amorphous films were found both at Si₃N₄ grain boundaries and at phase boundaries between Si₃N₄ and SiC. The Si₃N₄ grain boundary film thickness varied from 1 to 2. 5 nm. Two kinds of embedded SiC particles were observed: type A has a special orientation with respect to the matrix, and type B possesses a random orientation with respect to the matrix. The surfaces of type B particles are completely covered by an amorphous phase. The existence of the amorphous film between the matrix and the particles of type A depends on the lattice mismatch across the interface. The mechanisms of nucleation and growth of Ω-Si₃N₄ grains are discussed on the basis of these experimental results.     

Targeting Glycolysis in Macrophages Confers Protection Against Pancreatic Ductal Adenocarcinoma

Inflammation in the tumor microenvironment has been shown to promote disease progression in pancreatic ductal adenocarcinoma (PDAC); however, the role of macrophage metabolism in promoting inflammation is unclear. Using an orthotopic mouse model of PDAC, we demonstrate that macrophages from tumor-bearing mice exhibit elevated glycolysis. Macrophage-specific deletion of Glucose Transporter 1 (GLUT1) significantly reduced tumor burden, which was accompanied by increased Natural Killer and CD8+ T cell activity and suppression of the NLRP3-IL1β inflammasome axis. Administration of mice with a GLUT1-specific inhibitor reduced tumor burden, comparable with gemcitabine, the current standard-of-care. In addition, we observe that intra-tumoral macrophages from human PDAC patients exhibit a pronounced glycolytic signature, which reliably predicts poor survival. Our data support a key role for macrophage metabolism in tumor immunity, which could be exploited to improve patient outcomes.     

基于W5300的以太网数据传输硬件设计及优化

介绍了一种基于W5300芯片的以太网数据传输的硬件设计、优化方案,以及在方案设计和实现过程中的关键点和可优化部分.该设计实现了将数据以较稳定的速度传输,并且整个链路稳定可靠,已成功应用于工程实践中.     

化工管道系统安全防护技术的研究

化工管道系统是化工生产过程中的重要组成部分,发生破坏后会造成很严重的影响。通过对管道系统的破坏原因进行分析,得出主要是受到腐蚀和机械破坏的影响,并采取了相应的防护技术来应对,最后对化工管道系统的安全防护技术进行了总结。     

微机保护装置使用经验点滴

保护装置微机化是科技发展的必然,微机保护逐步成为保护装置的主流。定值整定、保护及二次回路接线、设备配合直接影响到装置的应用效果和被保护对象的安全运行。     

Experimental and Finite Element Wear Study of Silicon Nitride Against Alumina for Hip Implants with Bio-Lubricant for Various Gait Activities

Silicon - This paper presents an experimental approach to predict the friction and wear coefficients followed by finite element modeling (FE) to analyze the wear of silicon nitride sliding against...     

Composite Ceramic Based on Silicon Carbide

Refractories and Industrial Ceramics - An effective method for preparing dense granular ceramic from SiC with a residual porosity of less than 5.0% is the use of additives of oxide system eutectic...