Synthesis of a new chitosan derivative and assay of Escherichia coli adsorption

A new chitosan derivative is prepared using chitosan.Ethyl chlorocarbonate was first introduced to the hydroxyl group of phthaloylchitosan through a nucleophilic reaction.Hydrazine was then added to recover the amino groups of chitosan and promote cross-l     

Non-main Stream Plays Main Role in Shipbuilding Market

Comparing with both the major shipyards and shipping companies that were facing an market decline and hard time,the non-mainstream ship types,non-mainstream ship manufacturers and non-mainstream ship owners,as main roles,made a wonderful show of living and developing in 2009.     

Microfluidics-based assay on the effects of microenvironmental geometry and aqueous flow on bacterial adhesion behaviors

Abstract A new microfluidic system with four different microchambers （a circle and three equilateral concave polygons） was designed and fabricated using poly（dimethylsiloxane） （PDMS） and the soft lithography method. Using this microfluidic device at six flow rates （5, 10, 20, 30, 40, and 50 μL/h）, the effects of microenvironmental geometry and aqueous flow on bacterial adhesion behaviors were investigated. Escherichia coli HB101 pGLO, which could produce a green fluorescent protein induced by L-arabinose, was utilized as the model bacteria. The results demonstrated that bacterial adhesion was significantly related to culture time, microenvironment geometry, and aqueous flow rates. Adhered bacterial density increased with the culture time. Initially, the adhesion occurred at the microchamber sides, and then the entire chamber was gradually covered with increased culture time. Adhesion densities in the side zones were larger than those in the center zones because of the lower shearing force in the side zone. Also, the adhesion densities in the complex chambers were larger than those in the simple chambers. At low flow rates, the orientation of adhered bacteria was random and disorderly. At high flow rates, bacterial orientation became close to the streamline and oriented toward the flow direction; All these results implied that bacterial adhesion tended to occur in complicated aqueous flow areas.The present study provided an on-chip flow system for physiological behavior of biological cells, as well as provided a strategic cue for the prevention of bacterial infection and biofilm formation.     

城市突发大客流的轨道交通解决方案

对城市集会所产生的大型客流的交通组织、疏散方案进行研究分析,给出以轨道交通为主、多交通方式配合的解决方法,并重点阐述和分析轨道交通大客流运营组织方案的交路组织、站务管理、票务管理、运行图编排等方面,较为系统和明确地指出城市大客流的轨道交通运营措施和疏散方案。     

Mainstream Encounters the Dilemma Posed by Non-main Stream

In 2009,the global shipping and shipbuilding markets are loitering around in the"coldest winter".Though they display better than we image after"big adjustment"of stagnate,no obvious resuscitation has been seen,and the mainstream position of shipbuilders,shipowners and ship type in fOrmer days is also changing.     

前挤压工件和模具的温度分布有限元分析

在高精密冷成形加工中,工件和模具的温度变化直接影响工件的成形精度.通过对前挤压加工过程机械热力偶合有限元模拟,对材料的流动、由于塑性变形和接触面之间的摩擦所产生的热量、工件和模具中的热传导、工件与模具之间的热交换、在成形期间和其后冷却过程中工件和模具中温度的分布等进行了分析;对工件和模具的机械和热力学性能和诸如冲头的速度、摩擦系数等加工条件对温度在工件和模具中的分布的影响进行了研究.有限元模拟的结果表明,在成形加工中由于热膨胀和冷却的影响,工件和模具中温度的变化将影响工件的成形精度.工件的性能对热的产生和温度分布有决定性的影响;加工条件的变化会影响温度的高低和分布.     

批量生产多循环闭式冷锻铝材成形误差机械热偶合有限元分析

在冷成形加工中因为工件和模具中的温度随时间变化而使工件的成形误差也随之变化,以前的成形误差分析仅涉及单个工件加工循环.同时考虑机械效应和热力效应对成形误差的影响,对批量生产多循环闭式冷锻铝材成形过程中工件的成形误差进行了有限元分析,给出了一个包含成形各个阶段所产生的成形误差的误差分析公式.该公式可用于诸如挤压成形等其他成形工艺.这一分析工作为高精密成形误差补偿方法的研究提供了指导.