Molecular imprinting strategy for solvent molecules and its application for QCM-based VOC vapor sensing

Cross-linked polymers made of methyl methacrylate (MMA) as a monomer and divinylbenzene (DVB) as a cross-linking agent were prepared in the presence of toluene or p-xylene as a solvent. The cross-linked polymer prepared in toluene tended to sorb toluene vapor preferably, while the cross-linked polymer prepared in p-xylene sorbed p-xylene vapor preferably. The observed molecular recognition ability can be explained on the bases of an imprinting effect by solvent molecules. Molecularly imprinted polymer (MIP) powders were blended with PMMA, and the blended films were coated on a piezoelectric quartz crystal with a view to preparing QCM-based VOC sensors. The imprint effect was clearly observed, even in these blended films. The response of the sensor towards toluene or p-xylene vapor was reversible; however, the response time was slow due to the existence of the matrix polymer around the MIP particles.     

Lutein and lutein esters in marigold flowers by high performance chromatography

Lutein and lutein esters in marigold flowers was quantitatively determined by high performance chromatography (HPLC) with ODS-C18 column. A mixture of CH3CN-CH3OH-CH3COOCH2CH2 with volume ratio of 55:1:44 was used as mobile phase at a flow rate of 1.0mL/min and detection was carried out at 480 nm. The column temperature was about 20℃. The contents of lutein and lutein esters were determined by analytical curve of lutein since lutein and lutein esters have the same spectral characteristics. Determination results of hexane extracts and saponified samples of lutein show that the saponification transforms the esters into free lutein. The increase of the content of dipalmitate and palmitate stearate reveals that the reaction includes transesterifications.     

Synthesis and properties of novel amphiphilic sulfated ionomers by the ring‐opening reaction of an epoxidized styrene–butadiene–styrene triblock copolymer

A method for the synthesis of novel sulfated ionomer of styrene–butadiene–styrene triblock copolymer (SBS) was developed. SBS was first epoxidized by performic acid in the presence of a phase‐transfer catalyst; this was followed by a ring‐opening reaction with an aqueous solution of alkali salt of bisulfate. The optimum conditions for the ring‐opening reaction of the epoxidized SBS with an aqueous solution of KHSO₄ were studied. During the ring‐opening reaction, both phase‐transfer catalyst and ring‐opening catalyst were necessary to enhance the conversion of epoxy groups to ionic groups. The products were characterized with Fourier transform infrared spectrophotometry and transmission electron microscopy (TEM). After the potassium ions of the ionomer were substituted with lead ions, the lead sulfated ionomer exhibited dark spots under TEM. Some properties of the sulfated ionomer were studied. With increasing ionic groups or ionic potential of the cations, the water absorbency and emulsifying volume of the ionomer and the intrinsic viscosity of the ionomer solution increased, whereas the oil absorbency decreased. The sulfated ionomer possessed excellent emulsifying properties compared with the sulfonated SBS ionomer. The sodium sulfated ionomers in the presence of 10% zinc stearate showed better mechanical properties than the original SBS. When the ionomer was blended with crystalline polypropylene, a synergistic effect occurred with respect to the tensile strength. The ionomer behaved as a compatibilizer for blending equal amounts of SBS and oil‐resistant chlorohydrin rubber. In the presence of 3% ionomer, the blend exhibited much better mechanical properties and solvent resistance than the blend without the ionomer. SEM photographs indicated improved compatibility between the two components of the blend in the presence of the ionomer. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

技术进步经济效益评价——中国长城铝业公司水泥厂产出增长中技术进步作用的评价

本文通过运用“生产函数法”、“增长速度方程”来定量分析技术进步在长城铝业公司水泥厂产出增长中的作用,从中找出该水泥厂生产经营过程中存在的问题及未来发展方向。     

Tornado: A self-reconfiguration control system for core-based multiprocessor CSoPCs

In this work we present a self-reconfiguration control focused on multiprocessor core-based systems implemented on FPGA technology. An infrastructure of signals, protocols, interfaces and a controller is exposed to perform safe hardware/software reconfigurations. This infrastructure is part of the Tornado framework that includes other elements such as a multi-context assembler for a reconfigurable processor or a custom design flow developed for the Wishbone IP-Core interconnection specification. We present two applications where the presented control system has been applied, and it is compared with other available approaches.     

Pitting corrosion resistance of La added 316L stainless steel in simulated body fluids

Lanthanum (La), a rare earth element with anticoagulative and antiphlogistic function, was added into the medical grade 316L stainless steel in order to improve its biocompatibility. The corrosion resistance of the La added 316L steel in two different simulated body fluids, simulated blood plasma and Hank's solution, was evaluated. The result showed that the addition of La in the steel could largely affect the corrosion behavior of the steel. The steel with 0.01% La showed the widest passive region and the best resistance to pitting attack, within the addition range of La from 0.01% to 0.08%. The corrosion resistance improvement of La added 316L stainless steel is probably due to the effect of La on the purification of the steel, the modification of inclusions, and the passive film formation in the simulated body fluids.     

Etching-enhanced growth of indentation crack in barium titanate single crystal

The effect of etching on an unloaded indentation crack in a poled BaTiO₃ single crystal whose poling direction is lying in or normal to the indentation plane, has been investigated. The result showed that for the sample whose poling direction was lying in the indentation plane, the indentation cracks and 90° domain switching zones surrounded by two pairs of indentation cracks grew gradually during etching using HCl + HF aqueous solution, and reached saturation after etching for 30 s, however, the effect of etching on the crack length and the size of the domain switching zone was very small for the sample whose poling direction was normal to the indentation plane. Etching-enhanced domain switching and crack propagating is due to adsorption-decreased surface energy.     

Modeling,numerical optimization,and irreversibility reduction of a dual-pressure reheat combined-cycle

Optimizing the gas-turbine combined-cycle is an important method for improving its efficiency. In this paper, a dual-pressure reheat combined-cycle was modeled and optimized for 80 cases. Constraints were set on the minimum temperature-difference for pinch points (PP_m), superheat approach temperature-difference, steam-turbine inlet temperature and pressure, stack temperature, and dryness fraction at the steam-turbine’s outlet. The dual-pressure reheat combined-cycle was optimized using two different methods; the direct search and the variable metric. A technique to reduce the irreversibility of the steam generator of the combined cycle was introduced. The optimized and the reduced-irreversibility dual-pressure reheat combined-cycles were compared with the regularly-designed dual-pressure reheat combined-cycle, which is the typical design for a commercial combined-cycle. The effects of varying the inlet temperature of the gas turbine (TIT) and PP_m on the performance of all cycles were presented and discussed. The results indicated that the optimized combined-cycle is up to 1% higher in efficiency than the reduced-irreversibility combined-cycle, which is 2–2.5% higher in efficiency than the regularly-designed combined-cycle when compared for the same values of TIT and PP_m. The advantages of the optimized and reduced-irreversibility combined-cycles were manifested when compared with the most efficient commercially-available combined cycle at the same value of TIT.