Oxidative stress mediated cytotoxicity of biologically synthesized silver nanoparticles in human lung epithelial adenocarcinoma cell line

The goal of the present study was to investigate the toxicity of biologically prepared small size of silver nanoparticles in human lung epithelial adenocarcinoma cells A549. Herein, we describe a facile method for the synthesis of silver nanoparticles by treating the supernatant from a culture of Escherichia coli with silver nitrate. The formation of silver nanoparticles was characterized using various analytical techniques. The results from UV-visible (UV-vis) spectroscopy and X-ray diffraction analysis show a characteristic strong resonance centered at 420 nm and a single crystalline nature, respectively. Fourier transform infrared spectroscopy confirmed the possible bio-molecules responsible for the reduction of silver from silver nitrate into nanoparticles. The particle size analyzer and transmission electron microscopy results suggest that silver nanoparticles are spherical in shape with an average diameter of 15 nm. The results derived from in vitro studies showed a concentration-dependent decrease in cell viability when A549 cells were exposed to silver nanoparticles. This decrease in cell viability corresponded to increased leakage of lactate dehydrogenase (LDH), increased intracellular reactive oxygen species generation (ROS), and decreased mitochondrial transmembrane potential (MTP). Furthermore, uptake and intracellular localization of silver nanoparticles were observed and were accompanied by accumulation of autophagosomes and autolysosomes in A549 cells. The results indicate that silver nanoparticles play a significant role in apoptosis. Interestingly, biologically synthesized silver nanoparticles showed more potent cytotoxicity at the concentrations tested compared to that shown by chemically synthesized silver nanoparticles. Therefore, our results demonstrated that human lung epithelial A549 cells could provide a valuable model to assess the cytotoxicity of silver nanoparticles.     

SNI小鼠中调控ROS对疼痛和脊髓Pink1蛋白的影响及机制研究

目的:观察C57/BL6小鼠坐骨神经分支选择性损伤（spared nerve injury,SNI）后降低氧化应激反应对机械痛和脊髓中Pink1的表达影响,并探讨神经性疼痛中氧化应激对Pink1的可能的作用机制。方法:取60只小鼠,随机分为对照组（Control）、假手术组（Sham）、手术组（SNI）、SNI+Saline、SNI+苯亚甲基叔丁基氮氧化物（phenyl-N-tert-butylnitrone,PBN）5组。Control组不作任何处理,Sham组切开皮肤,分离出坐骨神经三支分支后缝合皮肤;SNI组游离并保留腓肠神经分支,结扎并切断胫神经;分别于14 d之后进行机械痛阈值检测。测定行为学后SNI组分别注射生理盐水（0.9%NaCl）和PBN。进行行为学测定,并分别检测氧化应激（GSH、SOD）水平;Western blot法检测腰段脊髓蛋白水平Pink1的表达变化。结果:SNI组与Control和Sham组相比,机械痛阈值显著降低,差异具有统计学意义（P<0.001）;SNI组腰段脊髓ROS水平升高（P<0.05）,注射PBN后ROS水平降低（P<0.001）;SNI小鼠中Pink1在蛋白水平表达增多（P<0.001）,降低ROS后脊髓中Pink1在蛋白水平表达降低（P<0.01）。结论:神经病理痛中降低线粒体内ROS水平则会改善小鼠神经性疼痛,靶向减少ROS的产生和改善Pink1有助于神经病理痛的治疗。     

高精密3-PPR并联平台的对位精度分析与试验研究

为了获得3-PPR并联平台的最佳对位精度,针对平台的结构布局与工作影响因素对其对位精度的影响,采用理论误差分析与实验验证的方法对平台进行对位精度研究,得出平台误差数学模型并确定在速度为7.5 mm/s、加速度为100 mm/s~2时平台的对位精度最好,上述分析结果为进一步改善与开发平台性能提供了必要的理论依据,可用于各种高精密对位场合,具有一定的实际应用价值。     

火灾探测性能综合评估试验平台设计

建筑的多功能、多用途使火灾探测器的应用环境变得日趋复杂，对产品的综合性能提出了更高的要求。针对特殊应用场所的特点，模拟和仿真探测器的应用环境，建立了一个集成平台对探测器的综合性能进行评估和测试。对总体方案和各部件单元的设计过程进行了论述。实际测试结果表明：系统达到预期设计目标，可以作为火灾仿真和探测器性能评估的专用工具，评估结果可以为产品改进和新产品开发提供帮助，也可以为工程评标和最终用户服务。     

整体钢平台模板体系风振响应时程分析

整体钢平台模板体系是适应超高层建筑主体施工需要的新型模板体系,在我国有广泛的应用前景。采用自回归过滤技术,考虑三维空间相关性,对具有随机性的脉动风荷载进行有效的模拟,根据模拟得到的风载时程曲线对整体钢平台模板体系的风振响应在时域内进行了分析,得出的相关结论可以为模板体系的设计和施工借鉴。     

苏通大桥北索塔墩钻孔平台施工技术

介绍在深水、大流速的北索塔墩区直接利用钻孔桩结构钢护筒搭设世界最大群桩基础桩基施工平台适用条件,设计与施工方法以及质量控制措施和实施效果。     

地下室大体积混凝土底板施工技术

介绍了地下室大体积混凝土底板的施工技术，提出了在原材料选用、配合比设计、混凝土施工和养护等方面应采取有效的措施，从而提高地下室大体积混凝土底板的抗渗能力。     

半高式屏蔽门在模拟风压荷载及人群挤压荷载作用下结构安全性能测试

提出了半高式屏蔽门结构安全性能的测试方案.通过对屏蔽门样机施加等效风压荷载和人群挤压荷载,模拟屏蔽门受荷载作用下的不利工况.通过试验反映了半高式屏蔽门的实际工作状况.     

Environmental Open Data in Urban Platforms: An Approach to the Big Data Life Cycle

ABSTRACT

Through a literature review, this paper proposes an assessment framework to evaluate environmental open data in urban platforms under the data life cycle approach. For this purpose, a set of quantitative and qualitative indicators has been defined for each of the stages of the data life cycle: acquisition, access, analysis, and application. As confirmation of the capabilities of this approach, we illustrate the results of its application in six data portals along with analyses, comparisons, and conclusions regarding the results. The cases reveal that an interest exists in providing environmental information, but the capability to transform the data information into knowledge relevant for cities is rather low.     

四面体框架积木式简易平台的研究

一种新型简易平台方案，利用井口隔水套管作为主立柱，套戳若干个四面体框架，加打二个辅桩腿，构成一个三极腿式导管梁平台．并在40m或27m水深、50年一遇的环境条件下确定了四面体框架的结构尺寸．计算分析数据以及与TTP、MOSSⅡ的比较认为，本方案更加安全可靠、简单经济，因而可行．