查看更多>>摘要：There is an increasing interest in the study of NO chemical affinities of organic nitrites, for the bio-logical and physiological effects of organic nitrites seem to be due to their ability to release NO. In this paper, NO chemical affinities of ten substituted benzyl nitrites were determined by titration calorimetry combined with a ther-modynamic cycle in acetonitrile solution. The results show that ΔHhet(O-NO)s of benzyl nitrites are substan-tially larger than the corresponding ΔHhomo(O-NO)s, suggesting that these O-nitroso compounds much more easily release NO radicals by the O-NO bond homolytic cleavage. It is believed that the structural and energetic information disclosed in this work should be useful in understanding chemical and biological functions of organic nitrites.
查看更多>>摘要：In the presence of the ionic liquid [bmim]Br/AICl3 as green reaction medium, methyl 12-benzoyldehy-droabietate was synthesized through Friedel-Craftsacylation reactions on the aromatic ring of methyl dehy-droabietate. The optimum synthetic conditions of the tar-get product were found to be as follows: molar ratio of methyl dehydroabietate to [bmim]Br to A1C13 to benzoyl chloride 1:4:8:8, reaction temperature 40℃, reaction time 2 h. The target product was analyzed and characterized by means of IR, MS, NMR and elemental analysis. The results show that this novel method has the advantages of mild condition, short reaction time and environmental benignity.
查看更多>>摘要：Molecularly imprinted polymers (MIPs), based on photografting surface-modified polystyrene beads as matrices, were prepared with acrylamide as the functional monomer, bovine hemoglobin as the template molecule and N, N'-methylene bisacrylamide as the crosslinker in a phosphate buffer. The results of IR, scanning electron microscope (SEM) and elemental analyses demonstrated the formation of a grafting polymer layer on the polysty-rene-bead surface. Subsequent removal of the template left behind cavities on the surface of the polymer matrix with a shape and an arrangement of functional groups having complementary binding sites with the original tem-plate molecule. The adsorption studies showed that the imprinted polymers have a good adsorption capacity and specific recognition for bovine hemoglobin as the template molecule. Our results demonstrated that the polymer prepared via the photografting surface-modified method exhibited better selectivity for the template. Attempts to employ the new method in molecular imprinting techniques may introduce new applications for MIPs and facilitate probable protein separation and purification.
查看更多>>摘要：A molecularly imprinted polymer (MIP), with special molecule recognition properties of ciprofloxacin (CIP), was prepared by thermal polymerization in which ciprofloxacin acted as template molecule, α-methacrylic acid (MAA) acted as functional monomer and trimethy-lolpropane trimethylacrylate (TRIM) acted as crosslin-ker. The optimized ratio was determined to be n(CIP): n (MMA):n(TRIM) = 1:6:16 by investigation of the effects of different concentrations of functional monomer and the crosslinker on the MIP's recognition properties. Equilibrium binding experiment was used to investigate the adsorption dynamics, the binding ability to template molecule and the substrate selectivity. Scatchard analysis was used to study the MIP's binding characteristic to tem-plate molecule. The results indicated that MIP has higher adsorption ability and selectivity. The equilibrium distri-bution coefficient KD was 41.64 and the separation factor α was 1.62. Scatchard analysis showed that two different kinds of binding sites were produced in the polymer matrix and their dissociation constants were calculated to be Kd1= 5.249×10-5 mol·L-1, Kd2=2.237×10-3mol·L-1.
查看更多>>摘要：A microfluidic chip featuring laminar flow-based parallel gradient-generating networks was designed and fabricated. The microchip contains 5 gradient genera-tors and 30 cell chambers where the resulting concentra-tion gradients of drugs are delivered to stimulate on-chip cultured cells. The microfluidics exploits the advantage of lab-on-a-chip technology by integrating the generation of drug concentration gradients and a series of cell opera-tions including seeding, culture, stimulation and staining into a chip. The microfluidic network was patterned on a glass wafer, which was further bonded to a PDMS film. A series of weir structures were fabricated on the cell culture reservoir to facilitate cell positioning and seeding. Cell injection and fluid delivery were controlled by a syringe pump. Steady parallel concentration gradients were gen-erated by flowing two fluids in each network. Over time observation shows that the microchip was suitable for cell seeding and culture. The microchip described above was applied in studying the role of reduced glutathione (GSH) in mediating chemotherapy sensitivity of MCF-7 cells. MCF-7 cells were treated with concentration gradients of As2O3 and N-acetyl cysteine (NAC) for GSH modu-lation, followed by exposure to adriamycin. GSH levels were down-regulated upon As203 treatment and up-regu-lated upon NAC treatment. Suppression of intracellular GSH by treatment with As2O3 has been shown to increase sensitivity to adriamycin. Conversely, elevation of intra-cellular GSH by treatment with NAC leads to increased drug resistance. The integrated microfluidic chip is able to perform multiparametric pharmacological profiling with easy operation, and thus holds great potential for extra-polation to the cell based high-content drug screening.
查看更多>>摘要：The principle of spontaneous monolayer dis-persion holds that active components of many supported catalysts will disperse spontaneously onto the surface of the carrier. The monolayer dispersion threshold of the active component on the surface of the carrier can be measured by X-ray diffraction phase-quantitative extra-polation method, etc. By measuring the monolayer disper-sion threshold, beneficial information on the surface structure and dispersion of supported catalysts can be obtained, and the optimal preparative processing condi-tions of the catalysts can be chosen. The proportion of the active component of many supported catalysts can be optimized while its monolayer dispersion threshold is observed. Mutation values of many physicochemical properties of supported catalysts are related to monolayer dispersion thresholds; the threshold effect on catalysts is apparent, and the proposal regarding the threshold effect provides instruction for the research on catalysts.
查看更多>>摘要：Photoisomerizations of 6-hydroxy-5,12-naphthacenequinone and its derivatives bearing methyl and phenyl group were theoretically investigated with den-sity functional theory and ab initio CIS method at the B3LYP 6-31G basis set, respectively. The obtained poten-tial energy curves revealed that a four-state cycle existed in the ground and excited states. It was also found that the activation energy for the methyl transfer was higher com-pared to that for the phenyl transfer, and this was consistent with the experimental results that the photoisomerization of the phenyl substituted derivative was more rapid than that of the methyl substituted derivatives. Further hybrid time-dependent density functional theory (TD-DFT) was used to investigate the absorption and fluorescence spectra of these compounds under solvent effect condition. The calculated values were in agreement with the experimental results and the excitation condition of photochromic reactions.
查看更多>>摘要：A water-soluble porphyrin dimer (Por Dimer) containing eight positive charges, bridged by 4,4'-dicarboxy-2,2'-bipyridine, has been synthesized. With Meso-tetrakis(N-methyl-pyridium-4-yl)porphyrin (H2TMPyP) as the reference compound, the water-sol-uble porphyrin dimer was investigated for its inter-action with DNA by absorption, fluorescence, and circular dichroism (CD) spectroscopy. The apparent affinity binding constant (Kapp= 1.2×106) of Por Dimer binding to CT DNA was measured by a com-petition method with ethidium bromide (EB) (that of H2TMPyP was 6.9×106). The cleavage ability of Por Dimer to pBR322 plasmid DNA was studied by gel electrophoresis. The results suggest that the binding modes of Por Dimer were complex and involve both intercalation and outside binding.
查看更多>>摘要：Three tetraorganodistannoxanes containing silicon were synthesized and their catalytic properties in esterification and acetalization were observed via the reac-tions of acetic acid with isoamyl alcohol and butyralde-hyde with glycol. The factors affecting the reaction, such as the catalyst dosage, reaction time and solvent, etc. were discussed. The results show that the three tetraorganodis-tannoxanes displayed similar good catalytic activities compared to dichlorotetrabutyldistannoxane in esterifica-tion and acetalization. When the dosage of [ClBu2SnOSn-(CH2SiMe3)2Cl]2 was 1.5% based on the mass of reactant, the yield of isoamyl acetate was 91.8% and the yield of butyraldehyde glycol aceta194.2%. The different alkyl and bridging groups on Sn sites in the structure of tetraorga-nodistannoxanes showed some influence on the catalytic activities of these compounds.
查看更多>>摘要：(E)-3-(2-chlorophenyl)- 1-(2,4-dichlorophenyl) prop-2-en-1-one was prepared from 2-chlorobenzalde-hyde followed by cyclization with hydrazine monohy-drate. Eight new 3-(2,4-Di-chlorophenyl)-5-(2-chlorophenyl)-4,5- dihydro-N-acylpyrazole derivatives were synthesized and characterized by elemental analysis, IR and 1H NMR spectroscopy. The experimental results show that the inhibition ratio of compounds 3f towards H. Oryzae and P. Oryzae at 50 mg.L-1 is 55.2% and 57.1%, respectively. The inhibition ratio of compounds 3g towards H. Oryzae, P. Oryza, S. Sclerotiorum at 50 mg·L-1 is 53.3%, 60.0%, 50.4% respectively.
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