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991.
The assembly strategy to prepare a monolayer of bovine serum albumin on the surface of silica gel supported gold nanoparticles is described. The stereo‐specific recognition ability of this material was evaluated by enantioresolution of Dansyl‐norvaline. For enantiomeric separation, the influences of buffer concentration and the concentration of organic modifier on the separation performance were investigated. A better separation in terms of enantioresolution and peak shape was found with the phosphate concentration at 30 mM. Moreover, the peak shape and resolution can be improved by the addition of methanol solution. Enantioresolution of Dansyl‐norvaline was obtained from this material at optimized conditions. It appears that the immobilization of a monolayer of bovine serum albumin on gold nanoparticles as the chiral selector of Dansyl‐derivative amino acid is promising. 相似文献
992.
丁基罗丹明B-碲钼杂多酸缔合显色反应的研究 总被引:1,自引:1,他引:1
本文研究了在聚乙烯醇(PVA)存在下,丁基罗丹明B(BRB)与碲钼杂多酸的离子缔合显色反应,碲钼杂多酸在0.025~0.075 mol/L硫酸溶液中形成丁基罗丹明B-碲钼杂多酸离子缔合物。形成酸度为1.26~2.16 mol/L硫酸,钼酸铵、丁基罗丹明B及PVA的适宜条件分别4.6×10~(-3)mol/,5.3×10~(-5) mol/L和0.16%。缔合物最大吸收波长为570 nm,表观摩尔吸光系数ε值为3.2×10~5 L·mol~(-1)·cm~(-1),符合比耳定律范围0~16μg Te/25ml。探讨了反应机理,用平衡移动法确定缔合物的摩尔比为Te:Mo:BRB=1:7:2,缔合物的可能化学式为(BRB)_2[TeMo_7O_(24)]。方法已用于烟尘中碲的测定,结果满意。 相似文献
993.
Andrew M. Piggott 《Tetrahedron letters》2007,48(42):7452-7455
Sulfinamides are important in enantioselective synthesis, as rare post-translational modifications of proteins and as isosteres of the amide bond. Little is known about the rates of hydrolysis for aliphatic sulfinamides or the mechanism of hydrolysis. In this Letter, we show that sulfinamides hydrolyse by predominantly a non-specific acid/base catalysis with phosphate buffer but by varying the buffer concentration, it was possible to determine the hydrolysis rates of a range of sulfinamides with water through non-linear least squares regression. 相似文献
994.
Ji‐Jiang Wang Meng‐Lin Yang Huai‐Ming Hu Prof. Dr. Gang‐Lin Xue Dong‐Sheng Li Qi‐Zhen Shi 《无机化学与普通化学杂志》2007,633(2):341-345
To determine the influence of the size of the aromatic chelate ligands on the frameworks of metal tretracarboxylate polymers, two new coordination polymers [Cd(btc)0.5 (2,2′‐bpy)] ( 1 ) and [Cd(btc)0.5(phen)]·H2O ( 2 ) (H4btc = biphenyl‐3,3′,4,4′‐tetracarboxylic acid, 2,2′‐bpy = 2,2′‐bipyridine, phen = 1,10‐phenanthroline) have been synthesized under similar hydrothermal conditions. In complex 1 , the dimeric Cd2 units are linked by bridging btc4? ligand to form a 2D layered network, whereas complex 2 possesses a 3D metal‐organic framework consisting of the dimeric Cd2 units. The differences of two metal‐organic frameworks demonstrate that the size of the rigid aromatic chelate ligands have an important effect on the structures of their complexes. Additionally, the two complexes show strong fluorescence in the solid state at room temperature. 相似文献
995.
996.
997.
《Mendeleev Communications》2020,30(1):97-99
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998.
A unique process of chemical oxidation polymerization of aniline using manganese dioxide (MnO2) as the oxidizing agent in an aqueous medium is described. The reaction between aniline and MnO2 follows a mechanism by which the organic monomer is oxidized while the metal oxide undergoes reductive dissolution. The effects of the amount of oxidizing agent and aniline, pH and temperature of the reactive system, type of acid on the yield and conductivity of polyaniline are discussed. The resulting polyaniline was characterized by [R and UV-Vis spectrometry. Polyaniline with a conductivity of 12.5 S/cm was obtained using 0.033 tool of aniline oxidized by 0.023 tool MnO2 in the presence of 100 mL of 2.7 mol/L HCI at 25℃ for 4 h. 相似文献
999.
The 1H, 13C and 1H, 13C COSY NMR spectra of salicylohydroxamic acid (sha) were measured in DMSO-d6 solution. The B3LYP GIAO method with the 6-311++G(d,p) basis set was chosen to reproduce the experimental spectra. All possible zusammen and entgegen conformers of monomeric sha were computed. After geometry optimisation (B3LYP/6-311++G(d,p)) only nine independent models of the molecule were shown to be stable. Additionally, the NMR chemical shifts of the Onsager model of the most stable monomer were calculated. The computed chemical shifts for the labile protons for all aforementioned geometries meaningfully underestimated experimental results suggesting the existence of the H-bonded structure of sha in DMSO solution. The most probable two dimeric structures along with two solvent-bounded aggregates were subsequently calculated at the same level of theory. The best agreement was obtained for sha H-bonded with two DMSO molecules (confirmed by the absence of concentration effect). The relative error not exceeding 10 and 4% for chemical shifts in 1H and 13C NMR spectra of sha–(DMSO)2, respectively, showed that the applied method with the B3LYP/6-311++G(d,p) basis set was efficient to predict the NMR shifts of a compound with strong H-bonds. Thus, this allows to assign properly NMR resonances to specific structure formed in DMSO solution. 相似文献
1000.
Persson A Garde A Jönsson AS Jonsson G Zacchi G 《Applied biochemistry and biotechnology》2001,94(3):197-211
The conversion of sodium lactate to lactic acid with water-splitting electrodialysis was investigated. One way of reducing
the power consumption is to add a conductive layer to the acid compartment. Doing this reduced the power consumption by almost
50% in a two-compartment cell, whereas the electric current efficiency was not affected at all. Three different solutions
were treated in the electrodialysis unit: a model solution with 70 g/L of sodium lactate and a fermentation broth that had
been prefiltered two different ways. The fermentation broth was either filtered in an open ultrafiltration membrane (cut-off
of 100,000 Dalton) in order to remove the microorganisms or first filtered in the open ultrafiltration membrane and then in
an ultrafiltration membrane with a cut-off of 2000 Dalton to remove most of the proteins. The concentration of sodium lactate
in the fermentation broth was 70 g/L, as well. Organic molecules present in the broth (peptides and similar organic material)
fouled the membranes and, therefore, increased power consumption. Power consumption increased more when permeate from the
more open ultrafiltration membrane was treated in the electrodialysis unit than when permeate from the membrane with the lower
cut-off was treated, since there was a higher amount of foulants in the former permeate. However, the electrodialysis membranes
could be cleaned efficiently with a 0.1 M sodium hydroxide solution. 相似文献