Degradation of normal and proliferated peroxisomes in rat hepatocytes: regulation of peroxisomes quantity in cells

Degradation and turnover of peroxisomes is reviewed. First, we describe the historical aspects of peroxisome degradation research and the two major concepts for breakdown of peroxisomes, i.e., autophagy and autolysis. Next, the comprehensive knowledge on autophagy of peroxisomes in mammalian and yeast cells is reviewed. It has been shown that proliferated peroxisomes are degraded by selective autophagy, and studies using yeast cells have been especially helpful in shedding light on the molecular mechanisms of this process. The degradation of extraperoxisomal urate oxidase crystalloid is noted. Overexpressed wild-type urate oxidase in cultured cells has been shown to be degraded through an unknown proteolytic pathway distinct from the lysosomal system including autophagy or the ubiquitin-proteasome system. Finally, peroxisome autolysis mediated by 15-lipoxygenase (15-LOX) is described. 15-LOX is integrated into the peroxisome membrane causing focal membrane disruptions. The content of the peroxisomes is then exposed to cytosol proteases and seems to be digested quickly. In conclusion, the number of peroxisomes appears to be regulated by two selective pathways, autophagy, including macro- and microautophagy, and 15-LOX-mediated autolysis.     

Cyclic degradation of material in vehicle components

A nonstandard approach to the fatigue strength of materials and structures is proposed, within the framework of the complete-diagram method. The use of the cyclic-degradation model in calculating the life of vehicle components is illustrated. In supercritical cycling, linear summation of the damage is possible in some situations.     

Estimation of volume densities of hepatocytic peroxisomes in a model fish: Catalase conventional immunofluorescence versus cytochemistry for electron microscopy

Accurately accessing changes in the intracellular volumes (or numbers) of peroxisomes within a cell can be a lengthy task, because unbiased estimations can be made only by studies conducted under transmission electron microscopy. Yet, such information is often required, namely for correlations with functional data. The optimization and applicability of a fast and new technical proceeding based on catalase immunofluorescence was implemented herein by using primary hepatocytes from brown trout (Salmo trutta f. fario), exposed during 96 h to two distinct treatments (0.1% ethanol and 50 µM of 17α‐ethynylestradiol). The time and cost efficiency, together with the results obtained by stereological analyses, specifically directed to the volume densities of peroxisomes, and additionally of the nucleus in relation to the hepatocyte, were compared with the well‐established 3,3'‐diaminobenzidine cytochemistry for electron microscopy. With the immuno technique it was possible to correctly distinguish punctate peroxisomal profiles, allowing the selection of the marked organelles for quantification. By both methodologies, a significant reduction in the volume density of the peroxisome within the hepatocyte was obtained after an estrogenic input. The most interesting point here was that the volume density ratios were quite correlated between both techniques. Overall, the immunofluorescence protocol for catalase was evidently faster, cheaper and provided reliable quantitative data that discriminated in the same way the compared groups. After this validation study, we recommend the use of catalase immunofluorescence as the first option for rapid screening of changes of the amount of hepatocytic peroxisomes, using their volume density as an indicator. Microsc. Res. Tech. 78:134–139, 2015. © 2014 Wiley Periodicals, Inc.     

Erosion and strength degradation in alumina

The effect of multiparticle impact at 23 700 and 1000 °C on the erosion and strength degradation of sintered alumina was determined. Impact damage at normal incidence was characterized by numerous small pits consistent with grain boundary cracking. Neither erosion rate nor strength degradation for normal impingement depended strongly on temperature. Although erosion rate increased with increasing kinetic energy of the impacting particle, strength degradation leveled off at high kinetic energies, contrary to predictions based on elastic-plastic fracture. An alternative theory was developed on the basis of the observed damage morphology. This theory assumes that the kinetic energy of the impacting particle goes into grain boundary cracking and the subsequent grain fallout creates a hemispherical pit with an annular crack. This model correctly predicts the dependence of both erosion rate and strength degradation on the kinetic energy of the impacting particle. For impingement at low angles, impact damage was primarily by a ductile ploughing process. This caused erosion rates to be greater than that predicted on the basis of the brittle chipping mode of erosion, but strength degradation was less because the shallow elongated flaws are less severe than the pits produced by normal impact.     

微弱信号选频放大电路的研制

为提高弱信号检测中的信噪比,常采用选频放大电路放大微弱信号,然后利用自相关检测技术只提取所需信号,抑制噪声干扰信号.介绍了无限增益选频放大电路的研制技巧:第一级选频放大电路必须选择低噪声运算放大器,当使用超低噪声的运放时,电阻的热噪声是主要噪声源,串联在输入端的电阻其阻值应比较小.各级选频放大电路都必须选用温度系数小的电阻和电容,其中电容对频率的稳定性影响更大.在PCB布线时采用一点接地方法,避免后级电路通过电源和地线反馈至前级电路引起自激.研究表明,当选频放大电路输入端短路时,末级输出噪声超过30mVpp,就比较容易出现自激振荡.这可以作为确定选频放大电路极限放大倍数的依据.     

稀有放线菌的选择性分离

探讨了培养基、抑制剂及预处理方法等几个方面对稀有放线菌分离效果的影响,重点研究了分散和差速离心法,并应用形态观察和细胞壁化学组分分析对分离菌株进行了逐步筛分.结果表明分散和差速离心法综合运用了物理和化学手段,很好地破坏了土壤团粒的聚集,大大提高了稀有放线菌的分离效率;高氏一号培养基非常适合放线菌尤其是链霉菌的生长,HV琼脂培养基对稀有放线菌的选择性较高;浓度恰当的重铬酸钾可以抑制绝大多数土壤真菌和大多数土壤细菌,而不抑制放线菌,选择性高,效果好且价格便宜.     

选区粉末激光烧结(SLS)技术

介绍了选区粉末激光烧结技术（SLS）在国内的发展现状，并对该项技术的使用范围和优点进行了详细说明．并举出了具体应用实例。     

Selective contrast in electron microscopy of crystalline cytochrome oxidase

We have used various techniques for preparation of specimens for electron microscopy in order to selectively contrast different regions of vesicle crystals of cytochrome c oxidase dimers. The results are consistent with a dimer composed of two y-shaped monomers [Fuller et al., J. Mol. Biol. 134 (1979) 305] aligned along one pair of arms with the other pair of arms approximately 70 A apart. The four arms of the monomers lie within and perpendicular to the lipid bilayer in which the dimer is embedded, and the arms protrude approximately 25 A from the lipid bilayer on the matrix side of the membrane. The cytoplasmic side domains of the two monomers split away from one another forming a large cleft in the dimer. Monovalent antibodies (Fab fragments) to subunit IV appear to bind to the two monomer arms which are closely apposed across the two-fold axis of the dimer.     

Grease degradation in a bearing simulation device

In this study, a ball-on-disc traction (MTM) device has been used to degrade grease under controlled thermal and shear conditions over an extended period. The tests were run under both fully flooded and semi-starved conditions to simulate the lubricant supply levels found in bearings. A simple lithium hydroxystearate grease with and without an additive package was used. At the end of the test Infrared micro-reflection spectra were taken from the track and surrounding grease to determine lubricant film composition. These results were compared to IR reflection analysis of lubricant films in used bearings. The MTM results show that in the semi-starved tests the grease “runs-in” during the first few cycles as the friction coefficient drops giving a low, stable value comparable to the fully flooded condition. During initial overolling the grease is shear degraded releasing mobile lubricant, which replenishes the contact and reduces starvation. IR analysis of the lubricant film in and around the track has shown evidence of the local degradation, the formation of thickener-rich layers and new chemical species. The unadditised grease failed towards the end of the test due to incipient starvation, which was exacerbated by the formation of oxidised thickener deposits in the track. The IR spectrum from this film was very similar to that found in some bearing samples.     

超声波辅助选择性电沉积技术研究进展

选择性电沉积技术可用于机械零件局部表面功能性涂层的制备,还可用于局部损失部位的尺寸恢复,该技术具有沉积电流密度大、沉积速度快的特点,但同时存在沉积层残余应力大、易产生裂纹、质量不均匀等不足。将超声波引入选择性电沉积可减小沉积层的内应力,提高沉积层的硬度和耐腐蚀性能,实现机械零件局部高性能涂层的制备及小型精密件的快速成形。介绍了浸没式超声辅助选择性电沉积、超声辅助喷射电沉积以及工件振动式超声辅助喷射电沉积等超声波在选择性电沉积技术中的应用方式,重点介绍了超声波对镀层表面形貌、相结构、硬度、耐磨性、耐腐蚀性等的影响,探讨了超声空化、热效应和机械效应等超声波影响选择性电沉积的机理,并指出了超声波辅助选择性电沉积技术存在的问题及发展方向。     

频率选择表面天线副反射面研制

频率选择面（FSS）是近年来发展较快的新型结构功能件,芳纶纤维复合材料是一种比重小、强度、刚度高、介电常数小的高性能材料。文中详细论述了采用芳纶纤维复合材料研制频率选择表面天线副反射面的全过程,产品电性能良好,可实现双频段使用,具有较大经济效益。     

选择性激光烧结试验研究

在自行研制的实验型选择性激光烧结设备的基础上,进行了各种形状零件烧结实验研究。对比线扫描和分形扫描烧结成型零件的性能,以及激光功率神经网络控制与恒定功率控制两种功率控制方法,发现采用激光功率神经网络控制的分形扫描烧结而成的试件效果最好。     

钯选择性电沉积过程控制方式

因为吸氢严重,一般的沉积工艺得到的钯镀层上存在气孔、裂纹等缺陷。利用正交设计研究了钯选择性电沉积过程,发现在移动阳极的作用下,钯选择性电沉积中离子扩散速度加快,使控制步骤由一般电沉积的扩散和电化学联合控制转为主要由电化学控制。AFM观察表明,键层没有出现裂纹和气孔,质量颇好。     

金刚石薄膜选择生长技术

以金刚石微马达和微型谐振子结构制备为例,介绍化学气相沉积金刚石薄膜的两种选择生长技术。     

用遗传算法估计图像退化系统函数

目前关于图像恢复的算法有很多,而这些算法大多是基于退化函数或者点扩展函数的知识进行的。当对退化函数先验知识不足时,设计出的恢复滤波器的恢复效果必将不够理想,因此有必要在设计恢复滤波器之前做系统的退化函数估计。遗传算法是一种成熟稳定的仿生物进化的全局寻优算法,由于遗传算法控制参数少、自适应度高,将选择该方法做退化函数的估计。实验结果表明,遗传算法从全局寻优的角度出发,能够较为精确地估计退化系统函数。     

Model of coating wear degradation in precision glass molding

Coatings in precision glass molding (PGM) experience severe thermo-chemical and thermo-mechanical loads during several hundred or thousand pressing cycles. Until now, little is known about the integrity loss of protective coatings for these applications. Gaining knowledge of fundamental mechanisms on the functional degradation of protective coatings is of great interest. The work presented in this paper investigates compositional changes in the surface-near region of precious metal PVD-coatings after being annealed in hot glass contact. Different characteristic wear zones identified on the samples have been analyzed by light microscopy, SEM/EDX, as well as X-ray photoelectron spectroscopy (XPS). The results are compared to the wear stages observed on molds used in industrial production. A qualitative model for the degradation of the substrate-coating system is proposed, ranging from the initial phases of material alteration to the final coating breakdown. In addition, indications that glass components might play a role in the overall degradation process were found but could not be revealed in detail. With regards to highly precise molding tools for PGM, further work should be focused on the initial phase of wear, since the end of service life time is reached at early degradation stages, far before the coating flake-off.     

选择性氢含量分析仪在炼厂气分析中的应用

介绍了HCMH-100气中氢含量测定仪在不同类型炼厂气体样品氢含量分析中的应用.实验结果表明,该型仪器对炼厂气中常见的轻烃(C1-C5烃)、非烃(O2、N2、H2O、CO、CO2等)、二氧化硫和硫化氢等都有良好的选择性,在常量范围(0.1%-100%)内对氢的响应有良好的线性,因此对各类炼厂混合气体样品中的氢气有良好的选择性定量检测功能,具有操作简便,适用范围宽,分析结果可靠,分析速度快等特点,可以作为炼厂控制分析的专用仪器,应用于实际炼厂气体样品中氢的定量分析.     

选择性激光熔化成形瞬态温度场数值模拟

为揭示选择性激光熔化成形的机理,初步建立了其熔化过程的传热理论模型;考虑温度变化对材料热物性参数的影响,利用ANSYS参数化设计语言(APDL)建立了有限元数值模型并进行了温度场求解.计算结果显示:熔化成形过程中温度场等值线呈椭圆状,已凝固部分在光斑再次扫描至邻近部位和上层粉末时由于热传导作用而发生重熔;熔池的尺寸大小随吸收能量的增加而逐渐增大,由初始宽约0.2mm增至0.25mm左右;温度场分布均匀、温度梯度小可减小零件的翘曲变形;基板温度随时间的推移而逐渐升高.     

EPA选择性的强制检查应对策略

随着小型通用汽油机公司申请美国EPA排放认证的数量不断增多,美国EPA开始实施选择性的强制检查,本文将通过对美国EPA相关法规进行简要说明,针对美国EPA选择性的强制检查提出应对策略建议,帮助小型通用汽油机企业顺利通过美国EPA选择性的强制检查。