CSRe团簇内靶温度闭环控制器设计；Design of Closed Loop Temperature Controller for CSRe Internal Target System

介绍了国家重大科学工程项目——兰州重离子加速器冷却存储环(HIRFL-CSR)的实验环(CSRe)团簇内靶温度闭环控制器的设计。该控制器给气体喷嘴处测温电阻提供长时间稳定度为0.1%的1mA恒定电流,通过12位ADC得到喷嘴温度,并通过混合信号处理器MSP430F149来实现制冷/加热闭环操作。在多种不同实验气体的情况下,该控制器的温度控制精度小于0.5K。目前,该控制器在现场工作良好。

Regio-regular structure high molecular weight poly(propylene carbonate) by rare earth ternary catalyst and Lewis base cocatalyst

Lewis base modification strategy on rare earth ternary catalyst was disclosed to enhance nucleophilic ability of active center during copolymerization of carbon dioxide and propylene oxide (PO), poly(propylene carbonate) (PPC) with H-T linkages over 83%, and number-average molecular weight (M-n) up to 100 kg/mol was synthesized at room temperature using Y(CCl3OO)(3)-ZnEt2-glycerine catalyst and 1,10-phenanthroline (PHEN) cocatalyst. Coordination of PHEN with active Zinc center enhanced the nucleophilic ability of the metal carbonate, which became more regio-specific in attacking carbon in PO, leading to PPC with improved H-T linkages.

A novel way to synthesize high regular and periodic organic mesoporous silicas

Organic mesoporous silicas (OMSs) were synthesized in the presence of urea via one-pot synthesis method, in which tetraethyl orthosilicate (TEOS) and 3-aminopropyltriethoxysilica (APTES) were used as the silica resources, non-ionic surfactant was used as the template. XRD results showed that the average periodic mesopore sizes of OMSs in the presence of urea were larger than those in the absence of urea. It was also found that the pore sizes of the products in the presence of urea distributed more narrowly than those in the absence of urea, and the contents of organosiloxane incorporated into OMSs, the pore wall thicknesses, the pore volumes and the surface areas of the products all increased with the use of urea. This shows a novel way to synthesize high regular and periodic organic mesoporous silicas.

How to form regular polymer microstructures by surface-pattern-directed dewetting

The substrates with regular patterns of self-assembly monolayers (SAMs) produced by microcontact printing with octadecyltrichlorosilane (OTS) was employed to direct thin polystyrene dewetting to fabricate ordered micrometer scale pattern. The pattern sizes and pattern fashion can be manipulated by controlling the experimental parameters. The pattern formation mechanisms have been discussed. The dewetting pattern can be transferred to form PDMS stamp for future microfabrication process.

Formation of regular hole pattern in polymer films

Ordered macroporous materials recently have attracted much attention. A method that utilizes the condensation of monodisperse water droplets on a polymer solution is proposed for the preparation of honeycomb microporous films. Our results show that it is a general method that can be used for patterning a wide range of polymers. The presence of water vapor and polymer is necessary for the formation of regular holes in films. The formation of hexagonal packing instead of other kinds of packing takes place because the hexagonal packing has the lowest free energy. The formation mechanisms of regular hole pattern and imperfections in the hexagonal packing are proposed.