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771.
Abstract In this study the graft copolymerization of acrylamide (AAm) on swollen poly(ethylene terephthalate) (PET) fibers using cerium ammonium nitrate (CeAN) initiator was investigated. Five organic solvents, dimethylsulfoxide (DMSO), morpholine, acetic acid (HAc), n-butanol, and 1,2-dichloroethane (DCE), were used as swelling agents. DMSO was found to be the most suitable swelling agent. Solvent diffusion into the fibers was observed to increase with treatment time and temperature. The optimum graft yield was obtained when fibers were grafted after having been swollen in DMSO for a period of 1 hour at 140°C. Variation of graft yield with polymerization time and temperature, and monomer, initiator, and acid concentrations were investigated. Graft yields were observed to increase initially with polymerization time, then to level off, and were found to increase up to a certain monomer and Ce4+ concentration, then to decrease slightly. The effect of grafting on such fiber properties as diameter, viscosity, and moisture gain were also investigated. 相似文献
772.
Constantin Bolcu Gabriela Vlase Titus Vlase Paul Albu Nicolae Doca Eugen Şisu 《Journal of Thermal Analysis and Calorimetry》2013,113(3):1409-1414
Polymeric materials by polyaddition reaction between aminated maltose and methylene diisocyanate, in different molar ratio, were synthesized. Aminated maltose was obtained by functionalization at the reductive end with methylene dianiline, under soft reductive conditions. The addition reaction was certified by comparative FTIR and Raman spectra of reactants and obtained materials. The thermooxidative stability of these materials was established under non-isothermal conditions. The thermal stability decreases by increasing the isocyanate/aminated maltose molar ratio. 相似文献
773.
774.
P. Şteţiu 《Journal of Physics and Chemistry of Solids》1976,37(5):457-460
The paper presents some experimental data concerning Hall effect, Seebeck effect and electrical conductivity in bulk samples of Pb1?xCdxS solid solutions, in the temperature range 100–360 K. The results are discussed employing a theoretical model with isotropic isoenergetic surfaces and nonpuadratic dispersion law. At x = 0.06 the dominant mechanism for scattering the charge carriers involves optical phonons below Debye temperature and the state density effective mass is not essentially changed relative to pure lead sulphide. 相似文献
775.
M. TunÇ H. ErŞahan S. Yapici S. Şolak 《Journal of Thermal Analysis and Calorimetry》1997,48(2):403-411
In the present study, the kinetic parameters of the thermal decomposition of ulexite were investigated by using TGA data. For the kinetic analysis, the Suzuki and Coats-Redfern methods were applied. It was determined that the process fits a first-order kinetic model, and the value of the activation energies and frequency factors decreased with decreasing particle size, which can be attributed to the increasing particle internal resistance to the escape of water as the grain size increases. The activation energy values were found to be 47.34–60.01 kJ mol–1 for region I and 0.225–1.796 kJ mol–1 for region II for the range of particle size fraction used. The frequency factors were calculated to be 9821.8–524.9 s–1 for region I and 3.05×10–44–2.807×10–5 for region II for the same conditions. 相似文献
776.
Several new binuclear CuII, NiII, OVIV and MnII complexes of tridentate salicylaldimine (H2L), obtained from 3,5-di-t-butylsalicylaldehyde and o-aminophenol, have been prepared and characterized by analytical, spectroscopic (i.r., u.v.–vis., e.s.r.) techniques, magnetic and thermal measurements. The adduct formation or dissociation of these complexes in the presence of strongly coordinating solvents like pyridine and DMSO did not take place. The complexation of CoII with H2L is accompanied by intramolecular electron transfer from the metal to the coordinated ligand yielding the radical ligand CoIII complex (g = 2.003, A
Co = 10 G). The e.s.r. spectra of the CuII, OVIV and MnII complexes in the solid state and in solution are very broad due to intramolecular dipolar antiferromagnetic interactions. 相似文献
777.
A relationship between antimicrobial activities and the formation constants of amino acid-Schiff bases and their Cu(II) and
Ni(II) complexes was studied. For this purpose, a series of Schiff bases were prepared from DL-amino acids (DL-glycine, DL-alanine)
and halo aldehydes (5-chloro-2-hydroxybenzaldehyde, 5-bromo-2-hydroxybenzaldehyde). Schiff bases and their Cu(II) and Ni(II)
complexes were characterized by the elemental analysis, spectral analysis, magnetic moment (at ca. 25°C), molar conductivity,
and thermal analysis data. The complexes were found to have general compositions [ML(H2O)]. The protonation constants of the Schiff bases and stability constants of the complexes were determined potentiometrically
in a dioxane-water (1: 1) solution at 25°C and 0.1 M KCl ionic strength. Antimicrobial activities of the Schiff bases and
their complexes were estimated for six bacteria, such as Bacillus cereus RSKK 863, Staphylococcus aureus ATCC 259231, Micrococcus luteus NRLL B-4375, Escherichia coli ATCC 11230, Aeromonas hydrophila 106, Pseudomonas aeroginosa ATCC 29212, and the yeast Candida albicans ATCC 10239. The role of halogen substitution on the ligands, effect of the metal ion, and stabilities of the complexes are
discussed on antimicrobial activities.
The text was submitted by the authors in English. 相似文献
778.
Engin Şahin 《合成通讯》2020,50(4):549-557
AbstractAryl and heteroaryl chiral carbinols are useful precursors in the synthesis of drugs. Lactobacillus paracasei BD87E6, which is obtained from a cereal based fermented beverage, was investigated as whole cell biocatalyst for the bioreduction of different ketones (including aromatic, hetero-aromatic and fused bicyclic ketone) into chiral carbinols, which can be used as a pharmaceutical intermediate. The study shows that bioreduction of aryl, heteroaryl and fused bicyclic ketone (1-5) to their corresponding chiral carbinols (1a-5a) in excellent enantioselectivity (>99%) with high yields. This study gave the first example for an enantiopure production of (S)-6-chlorochroman-4-ol (3a), which has many antioxidant activity, by a biological method. For asymmetric bioreduction of other prochiral ketones, these results open way to use of L. paracasei BD87E6 as biocatalysts. Also, the present process shows a hopeful and alternative green synthesis for the production of enantiopure carbinols in a mild, inexpensive and environmentally friendly process. 相似文献
779.
Influence of the mineral matter content on the rate of heat release from Turkish lignites 总被引:1,自引:0,他引:1
In this study, combustion curves of twenty-five original and demineralized Turkish lignite samples were obtained through use of a differential thermal analyser. The lignite samples were demineralized by treatment with hydrochloric and hydrofluoric acids. Samples of 20 mg were heated up to 1074 K at a constant rate of 10 K min–1 in a 40 cm3 min–1 flow of dry air. The rates of heat release from the original and demineralized samples were compared and are discussed. 相似文献
780.
Erem Bilensoy Lale Doğan Murat Şen Atilla Hıncal 《Journal of inclusion phenomena and macrocyclic chemistry》2007,57(1-4):651-655
Inclusion complexes of the poorly-soluble antiestrogen drug tamoxifen citrate (TMX) were prepared with β-cyclodextrin (β-CD)
and 2,3-di-O-hexanoyl-β-cyclodextrin (β-CDC6) being natural and amphiphilic cyclodextrins, respectively using the co-lyophilization technique.
Complexation occurred in aqueous medium for natural cyclodextrin β-CD and a medium of water:ethanol mixture for the amphiphilic
cyclodextrin β-CDC6. The complexes were characterized using analytical techniques including Differential Scanning Calorimetry
(DSC), Fourier Transform Infrared spectroscopy (FTIR) and proton Nuclear Magnetic Resonance Spectrometry (1H NMR). Anticancer efficacies of the complexes were determined against MCF-7 human breast carcinoma cell line with MTT assay.
It was found that tamoxifen citrate can be incorporated in the cavity for β-CD and both in the cavity and the aliphatic chains
for β-CDC6. The latter having two hydrophobic sites for inclusion of water-insoluble drug exhibited significantly higher anticancer
efficacy accordingly. 相似文献