Synthesis and antimicrobial activity of Schiff base of chitosan and acylated chitosan

Chitosan, a biocompatible, biodegradable, nontoxic polymer, is prepared from chitin, which is the second most naturally occurring biopolymer after cellulose. Schiff base of chitosan, sorbyl chitosan, and p‐aminobenzoyl chitosan were synthesized working under high‐intensity ultrasound and their antimicrobial properties were analyzed against Escherichia coli, Staphylococcus aureus, and Aspergillus niger. The structures of the derivatives were characterized by FTIR spectroscopy and elemental analysis. The results of antimicrobial activities indicated that the antimicrobial activities of the derivatives increased with increasing the concentration. The antibacterial activity of schiff base of chitosan against E. coli was stronger, while acylated chitosan had better inhiting effect on S. aureus than others. It was also found that the antifungal activities of the derivatives were stronger than that of chitosan, and schiff base of chitosan was obviously superior to acylated chitosan. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

基于区间二型模糊推理的双容水箱液位控制系统研究(英文)

For dealing with large static error due to poor immunity of the traditional fuzzy control, a novel interval type-2 fuzzy control system is proposed. By extending the typical membership functions to interval type-2 membership functions, the proposed control system can efficiently reduce the uncertain disturbance from real environment without increasing the design complexity. The simulation results on the water tank level control system showed that the proposed method succeeded in better static and dynamic control with stronger robust performance than the traditional fuzzy control method.     

火力发电厂循环排污水处理回用技术的比较分析

根据实际工程案例对目前国内火力发电厂循环水排污水处理回用的3种技术方案进行了分析比较,包括处理工艺、效果及技术特点等,并对循环排污水技术的发展提出了建议。     

Co-doping effects of (Al,Ti, Mg) on the microstructure and electrical behavior of ZnO-based ceramics

Co-doped ZnO-based ceramics using Al, Ti, and Mg ions in different ratios were synthesized with the objective to investigate the doping effects on the crystalline features, microstructure and the electrical behavior. For Al and Ti doping, a coexistence of crystalline phases was shown with a major wurtzite ZnO structure and secondary spinel phases (ZnAl₂O₄, Zn₂TiO₄, or Zn_aTi_bAl_cO_d), while Mg doping did not alter significantly the structural features of the wurtzite ZnO phase. The electrical behavior induced by Al, Ti, and Mg co-doping in different ratios was investigated using Raman, electron paramagnetic resonance (EPR) and ²⁷Al and ⁶⁷Zn solid-state nuclear magnetic resonance (NMR). Al doping induces a high electrical conductivity compared to other doping elements. In particular, shallow donors from Zn_i-Al_Zn defect structures are inferred from the characteristic NMR signal at about 185 ppm; that is, quite far from the usual oxygen coordinated Al. The Knight shift effect emanating from a highly conducting Al-doped ZnO ceramics was considered as the origin of this observation. Oppositely, as Ti doping leads to the formation of secondary spinel phases, EPR analysis shows a high concentration of Ti³⁺ ions which limit the electrical conductivity. The correlation between the structural features at the local order, the involved defects and the electrical behavior as function of the doping process are discussed.     

化学激励燃烧合成SiC超细粉末的工艺和机理研究

研究了利用聚四氟乙烯（-C2F4-）n作活化剂时Si/C混合粉末在氮气中的燃烧行为，结果表明：少量聚四氟乙烯的加入就可有效激励Si-C弱放热反应，使之以燃烧合成方式生成SiC，氮气参与反应时可进一步提高燃烧反应温度，并且首先以气相-晶体机制生成Si3N4，然后在反应前沿分解为SiC，调整工艺参数可获得亚微米级SiC粉末，综合X射线衍射、差热/热量分析及扫描电镜观察，提出了Si-C-N-(-C2F4-）n体系中的燃烧反应机制，并从热力学角度对实验结果进行了讨论。     

The Moisture Distribution of High Moisture Content Rough Rice During Harvesting, Storage, and Drying

The kernel moisture content (MC) distribution of five varieties of double season rice was tested during the process of harvesting, drying, and tempering. Significant kernel MC variance was found to exist within the panicle. Binodal kernel MC distribution frequency was found at harvest. The MC distribution of five varieties during harvesting and drying showed similar trend of uniformity. To investigate the mechanism of moisture transport among rice kernels under low temperature, the kernel MC distribution of rice planted in Northeastern China was also investigated after stacked for over one month under the temperature of -20°C. The moisture exchange among rice kernels was found greatly influenced by environmental factors.     

油基体系下天然气水合物浆液流动实验研究

在多相流管输体系下,水合物浆液在流动过程中会遇到崎岖不平的地形地貌,此时采用倾斜管道显得尤为重要。因此,研究了天然气水合物浆液在倾斜管内的流动特性对堵塞管路的影响。在低温高压可视水合物实验环路上,开展了油基体系下油＋天然气的水合物堵管实验,探究了初始压力、初始流量等因素对天然气水合物浆液流动和堵管时间的影响。同时,利用实时在线颗粒测试仪,对水合物生成、流动及堵管过程中水合物颗粒的微观变化进行了分析。结果表明,随着初始压力增大,天然气水合物的诱导时间、生成时间和浆液流动时间均缩短,天然气水合物堵管趋势增大;随着初始流量增大,天然气水合物的诱导时间、生成时间和浆液流动时间均延长,天然气水合物堵管趋势减小。对水合物生成至堵管的过程以及堵塞机理进行了分析。对油基体系下天然气水合物堵塞管路的研究结果表明,在油基体系下可以通过减小初始压力、增大初始流量来有效地减小天然气水合物堵塞管路的概率。研究结果可为维持和保证天然气水合物在管道中的安全流动提供理论参考及依据。     

具有机器视觉系统的等离子清洗设备开发

机器视觉系统是指通过机器视觉产品(即图像摄取装置,分CMOS和CCD两种)把图像抓取到,然后将该图像传送至处理单元,通过数字化处理,根据像素分布和亮度、颜色等信息,来进行尺寸、形状、颜色等的判别,在现代工业领域具有广泛的应用。在三轴联动系统等离子设备的基础上,通过揉和新的视觉系统,形成新的具有视觉系统的等离子清洗设备,既是原设备的延伸也是一种创新的应用。     

Delmia环境下的自动化冲压生产线设计及仿真分析

文章通过对现有冲压企业中以人工操作为主的生产方式进行分类对比,探讨基于工业机器人的冲压自动化生产线改造。在Delmia环境下建立实际冲压生产线模型,运用甘特图等对冲压过程实现运动的同步控制、动态检查生产线运行状态及干涉碰撞,实现自动冲压生产线的运动仿真,其结果可为企业进行冲压生产自动化改造方案的优化提供依据。     

聚苯胺/活性炭复合材料的共价键构筑及电容性能

导电聚苯胺(PANI)与活性炭(AC)构筑复合电极材料是当前制备高性能超级电容器电极材料的热点研究方向。其关键点之一是制备出炭与PANI两种材料均匀分散、且具有相当牢固强度连接界面的复合材料。为此,以AC为基材,对其进行功能化处理后,将苯胺在其表面原位聚合,获得具有界面共价键连接的PANI/AC复合材料(PANI–c–AC)复合材料。通过扫描电子显微镜、元素分析、傅里叶变换红外光谱、X射线衍射仪及电化学工作站等测试并研究其结构与电容性能。结果表明,具有界面共价键连接的PANI–c–AC复合材料比电容值(393.3 F/g)最高,既优于单一AC(111.8 F/g)与PANI(296.2 F/g),也优于无共价键连接的PANI–AC复合材料(360.5 F/g)。