Constructing porous ZnO/SnO2 nanocomposites for the detection of methane at low operating temperature

Journal of Porous Materials - Aimed at detecting methane (CH4) gas at low operating temperature, porous ZnO/SnO2 nanocomposites were constructed through a simple two-step method. Pure SnO2 with a...     

Synthesis of 3D graphene/MnO2 nanocomposites with hierarchically porous structure for water purification

Journal of Porous Materials - In this work, a three-dimensional (3D) graphene/manganese dioxide nanocomposite (PGA/MnO2) with a hierarchically porous structure was prepared by facile steam...     

镀铜钢纤维表面改性及其耐腐蚀性能和黏结性能

为了改善镀铜钢纤维与水泥基体的黏结强度,用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(MPS)和γ-巯基丙基三甲氧基硅烷(MPTS)对镀铜钢纤维进行表面处理.采用红外光谱、扫描电子显微镜(SEM)、氯化钠溶液浸泡腐蚀试验和黏结强度测试来评价处理后镀铜钢纤维的性能.结果表明:MPTS与镀铜钢纤维表面发生了化学键合,提升了钢纤维表面粗糙度;经过MPS处理和MPTS/MPS组合处理的钢纤维腐蚀溶液的吸光度积分只有未处理组的91%和45%;经过MPS处理和MPTS/MPS组合处理的钢纤维从水泥基体中拔出时所做的功相对于未改性组分别提升了43%和224%,与水泥基体的黏结强度得到了相应提高.     

Monitoring wind effects of a landfall typhoon on a 600 m high skyscraper

This article presents the observations of the atmospheric boundary layer (ABL) and wind effects on a 600 m high skyscraper during a landfall typhoon. Wind structure and characteristics throughout the entire ABL are presented and discussed based on records from a Doppler radar wind profiler and near-ground measurements at several meteorological stations. Wind speed profiles with the feature of low-level jets and radial-distance and exposure dependences of gradient height are stressed. Afterwards, wind-induced pressures on building surfaces of the skyscraper are investigated with highlights on non-Gaussian probability distributions of negative pressures and vortex shedding occurred alternately at two sides of the building. The structural responses measured by both accelerometers and strain gauges are analyzed subsequently. Modal parameters of the skyscraper and their dependence on response amplitude are presented and discussed. This study aims to provide useful information for the wind-resistant design of skyscrapers in tropic cyclone-prone regions.     

Exposure to Diflubenzuron Results in an Up-Regulation of a Chitin Synthase 1 Gene in Citrus Red Mite,Panonychus citri (Acari: Tetranychidae)

Chitin synthase synthesizes chitin, which is critical for the arthropod exoskeleton. In this study, we cloned the cDNA sequences of a chitin synthase 1 gene, PcCHS1, in the citrus red mite, Panonychus citri (McGregor), which is one of the most economically important pests of citrus worldwide. The full-length cDNA of PcCHS1 contains an open reading frame of 4605 bp of nucleotides, which encodes a protein of 1535 amino acid residues with a predicted molecular mass of 175.0 kDa. A phylogenetic analysis showed that PcCHS1 was most closely related to CHS1 from Tetranychus urticae. During P. citri development, PcCHS1 was constantly expressed in all stages but highly expressed in the egg stage (114.8-fold higher than in the adult). When larvae were exposed to diflubenzuron (DFB) for 6 h, the mite had a significantly high mortality rate, and the mRNA expression levels of PcCHS1 were significantly enhanced. These results indicate a promising use of DFB to control P. citri, by possibly acting as an inhibitor in chitin synthesis as indicated by the up-regulation of PcCHS1 after exposure to DFB.     

拱悬挂结构在大跨体育建筑中的形态表现与应用解析

拱悬挂结构是混合吊挂结构体系中较为常见且极具表现特色的结构形式之一,在大跨体育建筑中多有应用.本文从结构受力及形态的角度出发,分别对拱悬挂结构的特质、应用形态和表现特征进行解析,为更广范意义上结构形态设计指导下的大跨建筑创作提供思路.     

文化再生之发展规划路程--以陕西礼泉县袁家村为例

袁家村从一个物质文化双重匮乏的村子,后以发展文化为基点,为乡村的发展提供了强有力的支撑,使之最终成为现代化文化产业示范基地,打造了全国知名的乡村旅游品牌。在这期间,袁家村经历了寻找文化、复制文化、创造文化、衍生文化四个过程。     

呼和浩特回族聚居区的保护与更新发展

本文以呼和浩特回族聚居区为切入点,分析其特色与保护价值。针对目前城市发展过程中存在的一系列问题,提出统一协调建筑特色、完善人性化设施、大力发展民族特色产业等观点。     

新型溴化聚醚PBrMEO的合成及表征

以1,4-丁二醇为起始剂,三氟化硼乙醚络合物为催化剂,3-溴甲基-3-乙基氧杂环丁烷为单体,二氯甲烷为溶剂,按阳离子开环聚合机理,首次合成出新型溴化聚醚(PBrMEO),用IR、1HNMR、GPC、TGA、DSC等测试方法对合成产物进行了表征.结果表明,制备出的PBrMEO均聚物Mn为3000,相对分子质量分布为1.243～1.301,Tg为32.36℃,熔程为118.96～132.84℃,热分解温度为337℃.     

基于重复控制的数控系统伺服调节技术的研究

针对数控活塞环车削周期性控制的特点,应用重复控制理论对活塞环车床数控系统伺服调节技术进行了研究。以M序列信号作为输入信号,采用最小二乘法首先对数控伺服系统模型进行了系统辨识;以辨识所得到的整个闭环伺服系统模型为调节对象,进行了重复控制器的设计,构建了适合于伺服系统调节的重复控制器;以Matlab/Simulink为工具对所构建的重复控制器进行了仿真比较,系统跟随误差由原来94.2%减少到11.1%;同时在自行开发的数控系统上进行实际试验比较,系统跟随误差也由87.9%减少到24.7%。通过试验表明,基于重复控制的伺服调节技术能有效地抑制周期运动中的跟随误差。