金属离子在煤界面吸附对煤成浆性的影响

本文研究了六种金属离子在三种煤表面的吸附规律，研究结果表明：铜离子能够改善煤的制浆效果，即铜离子加入煤浆中，分散剂的用量降低５０％，煤浆浓度提高；钙、镁、钴、锌离子对煤的成浆性不利的原因是它们不能有效地被吸附到煤表面，游离的金属离子和分散剂发生反应，使得吸附到煤表面的分散剂相对减少，煤的成浆性变差。     

Reaction of porous silicon with both end-functionalized organic compounds bearing alpha-bromo and omega-carboxy groups for immobilization of biomolecules

Both end-functionalized (alpha-bromo and omega-carboxy) compounds were first tested for the radical reaction on the silicon-hydride (Si-H) terminated porous silicon (PSi) with/without the presence of diacyl peroxide initiator under microwave irradiation. Then the carboxylic acid monolayers (CAMs) assembled on PSi through the robust Si-C bonds were converted to amino-reactive linker, N-hydroxysuccinimide (NHS)-ester, terminated monolayers. And finally two proteins of bovine serum albumin (BSA) and lysozyme (Lys) were immobilized through amide bonds. The optimum PSi membrane for protein immobilization without collapse, with parameters of porous radii 4-10 nm and depth 0.2-4.6 mum, was prepared from the (100)-oriented p-type silicon wafer. The chemically converted surface products were monitored with Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and field emission scanning electron microscopy (FESEM).     

The first mu3-oxalato-bridged copper complex with tridentate Schiff base ligand N-ethyl-N'-salicylidene-1,2-diaminoethane: synthesis,structure, and magnetic properties

The first mu(3)-oxalato-bridged copper(II) complex, [[Cu(3)(L)(3)(mu(3)-C(2)O(4))][Cu(L)(H(2)O)](ClO(4))(2)] x 0.5(H(2)O) x 0.5(CH(3)OH), where HL = N-ethyl-N'-salicylidene-1,2-diaminoethane, has been synthesized and characterized by variable-temperature magnetic susceptibility measurement. The complex exhibits ferromagnetic coupling between the oxalato-bridged copper atoms and antiferromagnetic coupling between the oxygen-bridged copper atoms.     

Synthesis, structure and X-ray excited luminescence of Ce-doped AREP2O7-type alkali rare earth diphosphates (A=Na, K, Rb, Cs; RE=Y, Lu)

The crystal structures of five new alkali rare earth diphosphates were obtained by Rietveld refinement of powder X-ray diffraction (XRD) profiles, including four alkali lutetium diphosphates ALuP₂O₇ (A=Na, K, Rb, Cs) and the low temperature phase of KYP₂O₇. The scintillation properties of Ce³⁺-doped AREP₂O₇ (A=Na, K, Rb, Cs; RE=Y, Lu) powder samples were studied under static and pulsed X-ray excitations, and featured outstanding scintillation properties with light yields 1–2 times of that of Bi₄(GeO₄)₃ and relatively short decay time of 20–28 ns. Considering the suitable emission wavelength range, large light yield, short decay time, and non-hygroscopic nature, Ce³⁺-doped AREP₂O₇-type alkali rare earth diphosphates are potential candidates for high-counting-rate scintillation applications.     

Synthesis and flocculation performance of graft copolymer of <Emphasis Type="Italic">N</Emphasis> -vinylformamide and poly(dimethylaminoethyl methacrylate) methyl chloride macromonomer

 A comb-structured polymeric flocculant was synthesized by the aqueous copolymerization of N-vinylformamide (NVF) with poly(dimethylaminoethyl methacrylate) quats (methyl chloride) macromonomer. The effects of temperature and macromonomer concentration on the copolymerization kinetics were determined experimentally. The copolymerization reactivity ratio was measured to be 3.82 and 6.39 for NVF and macromonomers with 50 and 100 repeating units when copolymerized with NVF. The copolymer samples were also subjected to a flocculation performance test and were found to be more effective than linear random cationic copolymers in terms of cationic content, flocculation rate, final turbidity levels, and floc strength. Received: 11 June 2001 Accepted: 9 August 2001     

Studies of the Methane Steam Reforming Reaction at High Pressure in a Ceramic Membrane Reactor

The effects of temperature and pressure on the steam reforming of methane 3H2+CO) were investigated in a membrane reactor (MR) with a hydrogen permeable membrane. The studies used a novel silica-based membrane prepared by using the chemical vapor deposition (CVD) technique with a permeance for H2 of 6.0×l0-8 mol·m-2·s-1·Pa-1 at 923 K. The results in a packed-bed reactor (PBR) were compared to those of the membrane reactor at various temperatures (773-923 K) and pressures (1-20 atm, 101.3-2026.5 kPa) using a commercial Ni/MgAl2O4 catalyst. The conversion of methane was improved significantly in the MR by the countercurrent removal of hydrogen at all temperatures and allowed product yields higher than the equilibrium to be obtained. Pressure had a positive effect on the hydrogen yield because of the increase in driving force for the permeance of hydrogen. The yield of hydrogen increased with pressure and reached a value of 73×10-6 mol·g-1·s-1 at 2026.5 kPa and 923 K which was higher by 108% than the value of 35×10-6 mol·g-1·s-1 obtained for the equilibrium yield. The results obtained with the silica-based membrane were similar to those obtained with various other membranes as reported in the literature.     

Construction and evaluation of nagR-nagAa::lux fusion strains in biosensing for salicylic acid derivatives

The NagR protein is a response regulatory protein found in the bacterium Ralstonia sp. U2 that is involved in sensing for salicylic acid and the subsequent induction of the operaon just upstream of its gene. The genes encoded for in this operon are involved in the degradation of salicylic acid. Escherichia coli strain RFM443 carrying a fusion of the Photorhabdus luminesscens luxCDABE operon with the nagR gene and upstream region of the nagAa gene was constructed and characterized with respect to its optimum temperature, its response time and kinetics, and its ability to deterctnumerous benzoic acid derivatives. Although capable of detecting 0.5 mM salicylic acid at any temperature between 28 and 40°C, this E. coli strain, labeled DNT5, showed its greatest relative activity at 30°C, i.e., the temperature at which the largest induction was seen. Furthermore, experiments done with numerous benzoic acid derivatives found the NagR protein to be responsive to only a few of the compounds tested, including salicylic acid and 3-methyl salicylic acid and 3-methyl saliyclic acid, and acetyl salicylic acid was the strongest inducer. The lower limits of detection for these compounds with E. coli strain DNT5 were also established, wit the native inducer, salicylic acid, giving the most sensitive response and detectable down to a concentration of about 2 μM. A second lux fusion plasmid was also constructed and transformed into an NahR background, Pseudomonas putida KCTC1768. Within this strain, NAGK-1768, the supplemental activity of the NahR protein on the nagAn promoter, was shown to extend both the range of chemicals detected and the sensitivity.     

压力流驱动电色谱分析方法及其若干色谱行为

压力流驱动电色谱分析方法是一种新型色谱技术。它组合了ＨＰＬＣ和电泳两种技术，为分离提供了更多可控制的因素。介绍了压力流驱动电色谱的装置和毛细管电色谱柱的装置方法，从理论上讨论了影响电色谱分离的因素并用实验数据加以证明。最后尝试性地将电色谱法用于测定香蕉样品中萨索啉（Ｓａｌｓｏｌｉｎｏｌ）等的含量。     

富烯碳原子簇的石墨层间闭合形成机理

本文提出了富烯碳原子簇的石墨层间闭合形成机理，由该机理推出的许多结果与实验事实符合很好。我们认为碳原子簇自由基的快速淬灭及其淬灭速度是富烯碳原子簇形成及其丰度的决定因素。由此得出富烯碳原子簇在给定实验条件下产生的必然性，并预言不同大小的富烯碳原子簇可以通过优化实验条件选择性地合成。     

Synthesis of Novel Dendrimers Containing Amino Acids and Peptides

Dendrimers are known for their well-defined, regular, highly branched architectures with a large number of functional groups1. Recently, dendrimers have been widely researched in different fields, such as molecular light havesting, catalysts, liquid cryst…