浅谈中小学教学楼电气设计

根据国家有关设计规范规定,从供配电系统、照明插座、弱电系统、防雷接地系统四个方面论述中小学教学楼电气设计的具体内容。     

Re-use of water treatment works sludge to enhance particulate pollutant removal from sewage

This paper attempted to study the feasibility of reusing water treatment works sludge ("alum sludge") to improve particulate pollutant removal from sewage. The main issues focused upon were: (1) the appropriate dosage of the alum sludge, (2) the appropriate operating conditions, and (3) the possible mechanisms for enhancement by adding alum sludge. Actual alum sludge and sewage were applied to a series of jar tests conducted under various conditions. It has been found that both the SS and COD removal efficiencies could be improved by the addition of the alum sludge, which was mainly attributed to the removal of relatively fine particles with a size of 48-200 microm. The appropriate dosage of the alum sludge was determined to be 18-20 mg of Al/L. Increasing the mixing speed or reducing the floc size of the alum sludge enhanced the SS and COD removal and the dispersed alum sludge could remove particulate contaminants with smaller size than the raw sewage. ToF-SIMS evidence revealed that the aluminum species at the surface of the alum sludge were effectively utilized for improving the SS and COD removal. It was postulated that the sweep flocculation and/or the physical adsorption might play key roles in the enhancement of particulate pollutant removal from sewage.     

Anaerobic stabilisation and conversion of biopolymers in primary sludge--effect of temperature and sludge retention time

The effect of sludge retention time (SRT) and process temperature on the hydrolysis, acidification and methanogenesis of primary sludge was investigated in completely stirred tank reactors (CSTRs). The CSTRs were operated to maintain SRTs of 10, 15, 20 and 30 days at process temperatures of 25 degrees C and 35 degrees C. The rates of hydrolysis and the biodegradability of primary sludge were assessed in batch reactors incubated at 15 degrees C, 25 degrees C and 35 degrees C. The results revealed that the major amount of sludge stabilisation occurred between 0 and 10 days at 35 degrees C and 10 and 15 days at 25 degrees C. Hydrolysis was found to be the rate limiting-step of the overall digestion process, for the reactors operated at 35 degrees C and 25 degrees C, except for the reactor operated at 10 days and 25 degrees C. At the latter conditions, methanogenesis was the rate-limiting step of the overall digestion process. Proteins hydrolysis was limited to a maximum value of 39% at 30 days and 35 degrees C due to proteins availability in the form of biomass. The biodegradability of primary sludge was around 60%, and showed no temperature dependency. The hydrolysis of the main biopolymers and overall particulate COD of the primary sludge digested in CSTRs were well described by first-order kinetics, in case hydrolysis was the rate-limiting step. Similarly, the hydrolysis of the overall particulate COD of the primary sludge digested in batch reactors were described by first-order kinetics and revealed strong temperature dependency, which follows Arrhenius equation.     

日本中小学校建筑抗震设计研究

文章在介绍日本抗震法规的历史发展情况、抗震标准的具体内容和建筑建造程序的基础上,对日本在系统的抗震检测基础上对中小学建筑物进行详细分类并制定出相应的抗震修复和加固措施的做法进行了研究,并总结归纳出对我国中小学校建筑设计的启示,以期为相关工作开展提供借鉴。     

A study of the mechanism of in vitro cytotoxicity of metal oxide nanoparticles using catfish primary hepatocytes and human HepG2 cells

Nanoparticles (NPs), including nanometal oxides, are being used in diverse applications such as medicine, clothing, cosmetics and food. In order to promote the safe development of nanotechnology, it is essential to assess the potential adverse health consequences associated with human exposure. The liver is a target site for NP toxicity, due to NP accumulation within it after ingestion, inhalation or absorption. The toxicity of nano-ZnO, TiO₂, CuO and Co₃O₄ was investigated using a primary culture of channel catfish hepatocytes and human HepG2 cells as in vitro model systems for assessing the impact of metal oxide NPs on human and environmental health. Some mechanisms of nanotoxicity were determined by using phase contrast inverted microscopy, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays, reactive oxygen species (ROS) assays, and flow cytometric assays. Nano-CuO and ZnO showed significant toxicity in both HepG2 cells and catfish primary hepatocytes. The results demonstrate that HepG2 cells are more sensitive than catfish primary hepatocytes to the toxicity of metal oxide NPs. The overall ranking of the toxicity of metal oxides to the test cells is as follows: TiO₂ < Co₃O₄ < ZnO < CuO. The toxicity is due not only to ROS-induced cell death, but also to damages to cell and mitochondrial membranes.     

关于"基泰"南京外交宾馆方案初始图的探究

在杨廷宝先生生前办公室里曾存放着一份建筑图纸——基泰工程司于1930年初设计的南京外交宾馆方案初始图。该文根据这份史料,再参考相关资料,探析了与此方案图相关的几个重要问题。更有意义的是,文章在最后分析了此方案对于杨廷宝先生的特殊含义：对传统建筑大屋顶形式的第一次真正尝试。     

主梁绝对最大弯矩的计算方法与特性研究

给出了一组平行荷载直接沿着纵梁移动时,主梁承受结点活载作用下的绝对最大弯矩的计算方法,并分析了主梁绝对最大弯矩的主要特性。填补丁现行结构力学教材以及工程力学手册中关于结点活载作用下,计算主梁绝对最大弯矩的空白,对于桥梁设计与安全评估具有一定的实用价值。     

郊居离学背景下乡镇小学学生通学出行特征研究——以南京市江宁区秣陵中心小学为例

在城乡统筹背景下,“撤点并校”政策的落实使得乡镇中心学校学生居住地与上学地距离较远——“郊居离学、通学难”现象日益突出。本研究以南京市江宁区秣陵乡镇中心小学为调研对象,在统计分析学生居住地—上学地空间分布、通学出行特征等综合信息基础上,对远距离上学学生的主导交通方式——校车的路线、通学时间、出行需求及意愿进行了剖析,并对校车与其他各出行方式的上学优劣势进行了比较。最后根据凋研结果,提出了优化学生通学出行方式的相应战略与措施,提高了乡镇学生就学可达性。     

The Analysis of the Lubrication Condition and Friction Losses of a Single Acting Cross Head Guide Shoe of a Low Speed Cross Head Diesel Engine: Part II — A Practical Model for the Determination of the Oil Film Thickness

The cross head guide shoe plate of a large diesel engine operates under a large normal force which presses it against the rails between which it executes both axial and transverse motion. In order to ensure the safe operation of an unconventional bearing such as the guide shoe system of the cross head engine, an algorithm that can be used to predict accurately the oil film thickness that can be achieved for all the engine's operating regimes, is invaluable. A solution of the three dimensional form of Reynolds differential equation can provide the requisite oil film thickness. However, with even the availability of very fast computers and large computer storage capacity this solution for a large axial bearing such as the guide shoe becomes impractical in terms of computation time and computer core requirements. This paper describes alternative simplified algorithm for accurate prediction of the oil film thickness developed in the guide shoe bearing at different operating regimes of the engine.     

拉米夫定联合TACE治疗原发性肝癌临床观察

目的研究拉米夫定联合经皮肝动脉栓塞化疗术(Transcatheter arterial chemoembolization,TACE)治疗HBV-DNA阳性肝癌的疗效。方法选取我院住院患者102例原发性肝癌患者为研究对象,分为TACE+拉米夫定治疗组(50例),TACE对照组(52例),分别进行治疗,观察2组患者HBV-DNA水平、肝功能指标和child评分。结果治疗组HBV-DNA水平、肝功能指标和治疗效果均优于对照组,差异具有显著性(P<0.05)。结论拉米夫定联合TACE治疗乙肝病毒相关性肝癌患者,可抑制病毒复制,提高治疗效果。