Influence of 4-N,N-dimethylaminopyridine on the photovoltaic performance of dye-sensitized solar cells with poly(ethyleneoxide)/oligo(ethylene glycol) blend electrolytes

4-N,N-Dimethylaminopyridine (DMAP) was introduced into poly(ethyleneoxide)/oligo(ethylene glycol) (PEO/PEG) electrolytes for dye-sensitized solar cells (DSCs). The improved photovoltaic performance of DMAP-doped DSCs was attributed to the integrated effects of the upward displacement of the TiO₂ band edge and the decrease in the electron recombination rate. Remarkably, the presence of DMAP suppresses electron recombination via two combined pathways involving the dissociation of triiodide to iodide by a complexation reaction and a modification of the surface state distribution in the band gap of TiO₂. With the addition of DMAP, the open-circuit voltage enhances dramatically. The short-circuit photocurrent density has a small increase at low DMAP concentration and drops afterwards. The power conversion efficiency is 4.07%, which corresponds to a 63% increase over that of the DSC without DMAP.     

Preparation and characterization of thermosensitive organic-inorganic hybrid microgels with functional Fe3O4 nanoparticles as crosslinker

A methodology is described for the preparation of thermosensitive organic-inorganic hybrid microgels with functional Fe₃O₄ nanoparticles as the crosslinker and N-isopropylacrylamide (NIPAm) as the monomer. Magnetic Fe₃O₄ nanoparticles were first prepared via a redox reaction in aqueous solution and then modified with 3-(trimethoxysilyl)propylmethacrylate (TMSPMA) via the silanization. The bonding of multiple TMSPMA monomers on the surface of Fe₃O₄ nanoparticles renders them as crosslinker. Surfactant-free emulsion polymerization (SFEP) of NIPAm was then carried out with the presence of TMSPMA-modified Fe₃O₄ nanoparticles at 70 °C in aqueous solution, leading to the formation of thermosensitive PNIPAm-Fe₃O₄ hybrid microgels crosslinked with Fe₃O₄ nanoparticles. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), thermogravimetric analysis (TGA), dynamic light scattering (DLS) and physical properties measurement system (PPMS) were then used to characterize the resultant hybrid microgels. The experimental results show that the PNIPAm-Fe₃O₄ hybrid microgels were spherical in shape with a large size distribution and the Fe₃O₄ nanoparticles were randomly distributed inside the microgels. The PNIPAm-Fe₃O₄ hybrid microgels were thermosensitive, exhibiting a reversible swelling and deswelling behavior as a function of temperature. The PNIPAm-Fe₃O₄ hybrid microgels also show superparamagnetic behavior at room temperature (300 K).     

制备重结晶碳化硅用α-SiC微粉的表面改性

将聚醚改性聚二甲基硅烷(PMPDMS)与α-SiC微粉按一定比例充分混合,于120℃烘干12 h后碾碎,放入刚玉坩埚内,在N2保护下以一定的加热制度进行热处理,然后分析其相组成、比表面积、烧结块密度及其显微结构的变化;同时以B4C微粉取代α-SiC微粉做同样处理后进行XRD和SEM分析,以确定包覆在B4C微粉表面的PMPDMS在热处理过程中是否生成了β-SiC.结果表明:1)包覆在B4C微粉表面的PMPDMS在试验确定的热处理条件下可以生成β-SiC;2)表面改性后α-SiC微粉相组成发生一定改变,比表面积增大,用其制成的烧结块的密度增大,显微结构更加致密,表明其烧结活性增强.     

高效液相色谱法测定三聚氰胺不同色谱柱的选择

用高效液相色谱法测定乳制品中是否含有三聚氰胺,在色谱柱的选择上,通过对C8柱和混合型强阳离子交换色谱柱进行样品分析比对,实验结果证明：其方法准确性可靠,样品采集时间短,定量准确,精密度高,操作方便,成本低。     

高效CM催化剂在UHMWPE生产中的应用

介绍了CM催化剂的制备、组成和结构,并与生产高密度聚乙烯用催化剂进行比较,发现CM催化剂具有较大孔容和孔径.将CM催化剂应用于超高相对分子质量聚乙烯(UHMWPE)工业生产,发现采用CM催化剂生产的UHMWPE产品颗粒分布集中,细粉含量少,从而证实了CM催化剂适合生产UHMWPE.     

Synthesis and characterization of alkali‐soluble photosensitive polysiloxane urethane acrylate

A new negative temperature coefficient of resistor (NTCR) thermistors based on nitrile butadiene rubber/magnetite (NBR/Fe₃O₄) nanocomposites were successfully fabricated by conventional roll milling technique. X‐ray diffraction and transmission (TEM) analysis showed that the product is mainly magnetite nanoparticles with diameter of 10‐13 nm. The microstructure of (NBR/Fe₃O₄) nanocomposites were examined by scanning electron microscopy (SEM) and FTIR spectroscopy. The dispersion of magnetite nanoparticles in the NBR rubber matrix and interfacial bonding between them were rather good. The thermal stability of nanocomposites was also obviously improved with the inclusion of the magnetite nanoparticles. The thermal conductivity, thermal diffusivity and specific heat of nanocomposites were investigated. The electrical conductivity of the NBR/Fe₃O₄ increases with the rise in temperature exhibiting a typical negative temperature coefficient of resistance (NTCR) behavior like a semiconductor. The nature of the temperature variation of electrical conductivity and values of activation and hopping energy, suggest that the transport conduction process is controlled by hopping mechanism. Values of characteristics parameters of the thermistors like thermistor constant, thermistor sensitivity and thermistor stability is quite good for practical application as NTCR devices at high temperature. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Involvement of HNP‐1 in different oxidation mechanisms in human endothelial cells

The objective of this study was to elucidate the different mechanisms of low‐density lipoprotein (LDL) oxidation by human endothelial cells. High level of LDL stimulated human alpha‐defensin 1 (HNP‐1) expression strongly, activated myeloperoxidase (MPO), and accumulated malondialdehyde (MDA). In addition, lipopolysaccharides (LPS) had similar effect, however the cell response occurred even earlier. After 12 h of LDL co‐culture, the cells were washed and fresh LDL was added again. MPO activity and MDA generation were increased. Adding fresh LDL after the LPS co‐culture for 3 h, a similar trend, however weaker effect was observed. Culturing cells with LDL and adding various kinds of calcium antagonists at the same time did not make obvious changes to the expression of HNP‐1. In contrast, culturing cells with LPS, calcium antagonists increased HNP‐1 expression. Adding the anti‐radical drug sodium ferulate had no significant effect on oxidative function activated by LDL, but the oxidation activated by LPS was suppressed significantly and the HNP‐1 expression was not changed significantly. The endogenous irritant LDL and the exogenous irritant LPS activated human endothelial cells in different manners and HNP‐1 expression changes were involved.     

Synthesis and characterization of a propargyl‐substituted polycarbosilane with high ceramic yield

A propargyl‐substituted polycarbosilane (PCS), namely, propargyl‐substituted hyperbranched hydrodipolycarbosilane (PHPCS), was prepared by a modified synthesis route, which involved Grignard coupling of partially methoxylated Cl₃SiCH₂Cl and CHCCH₂Cl, followed by reduction with lithium aluminum hydride. The resultant PHPCSs were characterized by gel permeation chromatography, Fourier transform infrared (FTIR) spectroscopy, and NMR. Moreover, the thermal properties of the PHPCSs were investigated by thermogravimetric analysis. The ceramic yield of PHPCS at 1400°C was about 82.5%, which was about 10 wt % higher than that of hyperbranched hydrodipolycarbosilane without the substitution of propargyl groups. The PHPCS‐derived ceramics were characterized by X‐ray diffraction (XRD), FTIR spectroscopy, and elemental analysis. The XRD and FTIR results indicate that the heat treatment significantly influenced the evolution of crystalline β‐SiC. It can be convenient to get near‐stoichiometric ceramics from PHPCS through the control of feed ratios of the starting materials. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121:3400–3406, 2011     

Synthesis and application of long‐chain alkyl quaternary ammonium‐functionalized hyperbranched polyester

A novel kind of macromolecule, long‐chain alkyl quaternary ammonium functionalized hyperbranched polyester (QHPE), was synthesized by the reaction of hyperbranched polyester Boltorn H30 (H30) and 2,3‐epoxypropyl alkyl dimethyl ammonium chloride under alkaline conditions in dimethylformamide. After modification, the hydroxyl terminal group of H30 was converted into an ammonium functional group. A series of products was obtained with different lengths of an alkyl chain (C8, C12, C16, and C18) in the ammonium functional group. All of the products were characterized by Fourier transform infrared and NMR spectroscopy. The application of QHPEs as accelerators for the alkaline hydrolysis of poly(ethylene terephthalate) (PET) fabric was studied. The influences of the structure of QHPEs and hydrolysis conditions, such as alkaline concentration, hydrolysis time, and temperature, on the weight loss of PET fabrics were investigated. The results indicated that QHPE was a novel, efficient accelerator for the alkaline hydrolysis of PET fabrics. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

改进尿素包装工艺 不断提高产品质量

通过对尿素包装工艺的不断改进，提高了尿素粒度、减少粉尘含量，效果明显。