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51.
Sevtap Yildiz Faruk Yilmaz Haluk Özbek Önder Pekcan Koi˙chi˙ Ito 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(12):1573-1588
Random copolymers of poly(ethylene oxide) macromonomer with p‐vinylbenzyl end‐functional group (PEOVB) and liquid crystalline monomer, namely 6‐(4‐cyanobiphenyl‐4′‐oxy)hexyl acrylate (COA), were prepared by conventional free radical polymerization. A living anionic polymerization technique was employed for the synthesis of PEO macromonomers bearing p‐vinylbenzyl moiety at one end. The photon transmission method was also applied to study the phase transitions of COA monomer and its random copolymer with PEO. It was found that, for both samples, the nematic‐smectic A transition is continuous, but the critical fluctuation regions do not allow to obtain 3D XY values. Instead, we have obtained the values close to mean field regime. Scaling of thermal hystersis for random copolymer sample near the nematic‐isotropic transition was studied as well. Thermal hysteresis loops were produced under linearly varying temperature. It was shown that the areas of the hysteresis loops scale with the temperature scanning rate with an exponent being equal to 0.614 which is in good agreement with the field‐theoretical value. 相似文献
52.
53.
İbrahim Erol Levent Özcan Sedat Yurdakal 《Journal of Thermal Analysis and Calorimetry》2013,114(1):377-385
The derivatives of styrene monomer, 4-chlorophenyl-4-vinylbenzyl ether (M1), 4-methoxyphenyl-4-vinylbenzyl ether (M2), 4-ethylphenyl-4-vinylbenzyl ether (M3) and 1-naphtylphenyl-4-vinylbenzyl ether (M4) were synthesized. The normal free radical polymerization of monomers in 1,4-dioxane were performed by using 2,2′-azobisisobutyronitrile as an initiator at 65 °C. The monomers and their homopolymers were characterized by FT-IR, NMR and elemental analyses measurements. The thermal stability of polymers was investigated by thermogravimetric and differential scanning calorimetric analysis. Thermal degradation activation energies of the polymers were calculated by the Ozawa and Kissinger methods. In addition, photo-stability tests of the polymers under near-UV irradiation were performed. 相似文献
54.
The interaction of cysteine (RSH) with a thiazide diuretic, hydrochlorothiazide (HCTZ) was characterized by UV-Vis absorption spectroscopy and square-wave voltammetry in Britton-Robinson (B-R) buffer solution (with pH 5, 7 and 9). On the square-wave voltamogram of cysteine, the reduction peak current of mercurous cysteine thiolate (Hg2(RS)2) decreased and its peak potential shifted to more positive values with the addition of HCTZ. This results showed that the RSH interacted with HCTZ. The stoichiometry of HCTZ-RSH molecular complex was determined by voltammetric data with the result of 1: 1. By using linear regression analysis of the voltammetric data at pH 5, 7 and 9, the apparent formation constants of HCTZ-RSH complex were calculated to be 9.54 × 103, 2.80 × 104 and 2.55 × 104 M?1, respectively. At the same time, this interaction was also supported by UV-Vis spectroscopic measurements. According to the voltammetric and spectroscopic results, it was suggested that the interaction mode between RSH and HCTZ molecules might be a combination of hydrophobic interactions and hydrogen bonds. 相似文献
55.
Ayşegül Doğan Emirhan Nemutlu M. Aykut Özek Hakan Eroğlu Sedef Kır M. Sinan Beksaç 《Chromatographia》2013,76(21-22):1513-1519
Pregnancy alters pharmacokinetic profile of many drugs, because of altering body volume and metabolism rate. Therefore, dosage rates and concentrations of drugs must be controlled during pregnancy. Here, we identified the pharmacokinetic profile of pre-operatively given cefepime in caesarean section and gynecological operations using a simple, rapid, cost-effective and valid liquid chromatographic method. The chromatographic separation was performed using 40 mM, pH 3.2 phosphate buffer containing 6 % methanol as mobile phase at 0.30 mL min?1 flow rate. Gradient elution with methanol was applied to get shorter analysis time without any interference from plasma endogens. During analyses, temperature of column, autosampler and detector were set as 30, 10 and 40 °C, respectively. The detection wavelength was 260 nm and ceftizoxime was used as internal standard. At the optimum conditions, the cefepime analysis from plasma samples was completed in 7 min. Cefepime was extracted from plasma samples using perchloric acid with a very high recovery rate (99.3 %). The method was fully validated according to the Food and Drug Administration guidelines for bioanalytical method validation, and found to be selective, linear, repeatable, reproducible and robust. After validation studies, the method was applied to five caesarean-sectioned and four non-pregnant sectioned women treated with pre-operative, prophylactic single intravenous dose of cefepime (1 g Maxipime®) in order to determine pharmacokinetic profile of cefepime. Peak serum concentrations of cefepime in caesarean-sectioned women at the arterial port after infusion was 70.11 ± 10.74 μg mL?1. The mean elimination half-life, volume of distribution and calculated area under the concentration–time curve (AUC)0–∞ were 1.10 ± 0.23 h, 14.22 ± 2.29 L and 101.55 ± 10.99 μg h mL?1 for caesarean-sectioned women; and 1.14 ± 0.21 h, 14.76 ± 2.92 L and 104.71 ± 36.34 μg h mL?1 for non-pregnant sectioned women, respectively. The area under curve, elimination half-life, maximum plasma concentration and the mean distribution volume of cefepime were not changed in case of pregnancy. 相似文献
56.
Dopamine, rotigotin, ladostigil, and rasagiline analogues 2-amino-4,5,6-trimethoxyindane and 1-amino-5,6,7-trimethoxyindane were synthesized starting from 5,6,7-trimethoxyindan-1-one for the first time with 34% and 45% total yields. α-Carboxylation of indanone, reduction of ketone group with Et3SiH, basic hydrolysis of ester, Curtius reaction of the acid, and addition of BnOH afforded the corresponding carbamate. Pd-C-catalyzed hydrogenolysis of carbamate and deprotonation of amine hydrochloride with NaOH gave the dopamine and rotigotin analogue 2-aminoindane. Reduction of 5,6,7-trimethoxyindan-1-one with NaBH4 afforded the alcohol, which was then converted to the azide derivative via Mitsunobu reaction with diphenylphosphoryl azide; Pd-C catalyzed hydrogenation of the azide to the amine hydrochloride and then deprotonation of the amine hydrochloride with NaOH furnished the ladostigil and rasagiline analogue 1-aminoindane. These amines and BnOH were reacted with CSI to produce sulfamoyl carbamates, which were converted to sulfamides via Pd-C-catalyzed hydrogenolysis reaction with 20% and 25% total yields. 相似文献
57.
N-Aryl-N,N-diphenacylamine dioximes were prepared by the reaction of corresponding arylamines with α-bromoacetophenone oxime in ethanol-water at room temperature. These compounds reacted with aryl isocyanates in acetonitrile to give imidazooxadiazolones 9. The probable mechanism of the reaction is discussed. 相似文献
58.
Serkan Yavuz Hamdi Özkan Gülçin Tok Ali Dişli 《Journal of heterocyclic chemistry》2013,50(6):1437-1440
The substituted pyrolidine derivatives with high stereoselectivity were obtained through cycloaddition reaction in the presence of a Lewis acid namely diethylzinc by solvent‐free grinding method. 相似文献
59.
60.
Nilgun Demir Urkiye Akar Tarim Maria-Ana Popovici Zehra Nur Demirci Orhan Gurler Iskender Akkurt 《Journal of Radioanalytical and Nuclear Chemistry》2013,298(2):1303-1307
The mass attenuation coefficients of water, bakelite and concrete sample defined in the simulation package were obtained using the FLUKA Monte Carlo code at 59.5, 80.9, 140.5, 356.5, 661.6, 1173.2 and 1332.5 keV photon energies. The results for the mass attenuation coefficients obtained by simulation have been compared with experimental and the theoretical ones and good agreement has been observed. The results indicate that this process can be followed to determine the data on the attenuation of gamma-rays with the several energies in other materials. Also, the deposited energy by 661.6 keV photons at several thicknesses of each media was determined as being an important data for radiation shielding studies. 相似文献