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971.
Unsymmetric tridentate ligands, 4-methyl-2,6-di(4-methyliminomethyl)phenol (HL1), 4-(t-butyl)-2,6-di(4-methylphenyliminomethyl)phenol (HL2), 2,6-di(4-bromophenyliminomethyl)-4-methylphenol (HL3), 2,6-di(4-bromophenyliminomethyl)-4-(t-butyl)phenol (HL4), 2,6-di(4-hydroxyphenyliminomethyl)-4-methylphenol (HL5) and 4-(t-butyl)-2,6-di(4-hydroxyphenyliminomethyl)phenol (HL6), and their binuclear CuII, CoII and NiII complexes were synthesized and characterized by elemental analysis, FT-IR, u.v.-vis spectrometry magnetic moments, 1H(13C)-n.m.r. and mass spectral data. Also, the electrical conductivities of the complexes have been measured using 10-3 M solutions in MeCN. The complexes are weak electrolytes. In the electronic spectra of the complexes of the HL1-HL6 ligands, the 480-410 nm band has been determined as the charge-transfer band. While the HL5 and HL6 ligands have five potential donor atoms, other ligands have only three. Protonation constants of the ligands have been studied in dioxan-water mixtures. In addition, the antimicrobial properties of the ligands and their metal complexes have been studied:Bacillus megaterium, Micrococcus luteus, Corynebavterium xenosis, Enterococcus faecalis, bacteria and Saccoramyces cerevisia, yeast. The keto-enol tautomeric equilibria of the ligands have been investigated in polar and non-polar solvents. 相似文献
972.
Toksoz S Mammadov R Tekinay AB Guler MO 《Journal of colloid and interface science》2011,356(1):131-137
Self-assembling peptide amphiphile molecules have been of interest to various tissue engineering studies. These molecules self-assemble into nanofibers which organize into three-dimensional networks to form hydrocolloid systems mimicking the extracellular matrix. The formation of nanofibers is affected by the electrostatic interactions among the peptides. In this work, we studied the effect of charged groups on the peptides on nanofiber formation. The self-assembly process was studied by pH and zeta potential measurements, FT-IR, circular dichroism, rheology, atomic force microscopy, scanning electron microscopy and transmission electron microscopy. The aggregation of the peptides was triggered upon neutralization of the charged residues by pH change or addition of electrolyte or biomacromolecules. Understanding the controlled formation of the hydrocolloid gels composed of peptide amphiphile nanofibers can lead us to develop in situ gel forming bioactive collagen mimetic nanofibers for various tissue engineering studies including bioactive surface coatings. 相似文献
973.
Binnur Aydogan Yasemin Yuksel Durmaz Muhammet U. Kahveci Mustafa Uygun M. Atilla Tasdelen Yusuf Yagci 《Macromolecular Symposia》2011,308(1):25-34
Summary: New photoiniting systems for cationic polymerization acting at near UV and visible range are described. The applicability of acylgermanes as a new class of free radical promoters for photoinitiated cationic polymerization is demonstrated. Moreover, the use of substituted vinyl halides as source for readily oxidizable free radicals is presented. The polymerization of vinyl ethers can be initiated by the irradiation of substituted vinyl halides in the presence of Lewis acids such as zinc halide. Furthermore, possibilities for conducting cationic polymerization at visible range by using highly conjugated thiophene derivatives are demonstrated. Mechanistic aspects of all initiating systems are discussed. 相似文献
974.
Serkan Erdemir Mustafa Yilmaz 《Journal of inclusion phenomena and macrocyclic chemistry》2012,73(1-4):141-150
Two novel chiral di- and tri-amide derivatives of p-tert-butylcalix[4]arene were synthesized by (R)-(+)-1-Phenylethylamine via convenient reactions and then immobilized on aminopropyl functionalized silica particles. The prepared chiral calix[4]arenes and their silica polymers (Calix-SP1 and Calix-SP2) were characterized using 1H NMR, 13C NMR, FT-IR, and thermal and elemental analysis techniques. 相似文献
975.
Gençaslan M 《The Journal of chemical physics》2012,136(22):224901
This paper is a contribution of our systematic investigation of the global phase behaviors of the chain molecules mixtures, i.e., polymer mixture solutions. The phase behavior of fluid mixtures is understood by the critical lines in fluid-gas diagrams. The critical lines of binary fluid system may, under circumstances, exhibit closed loops in the critical lines. A distinction is made between free critical loops, as described by type VI in the Scott and van Konynenburg classification, and "rooted" critical loops, as found in the shield region. We define rooted loops as closed critical lines that are attached to the critical line structure by means of unstable critical line. We obtain the rooted loops in the global phase diagrams of the polymer mixture solutions within the framework of a model that combines the lattice gas model of Schouten, ten Seldam and Trappeniers with the Flory-Huggins theory, and we present the influence of the chain length of long molecules on the rooted critical loops. We present the results in the density-density and the temperature (T)-pressure (P) planes in detail. 相似文献
976.
Mustafa M. Musameh Daniela Klink Jonghyun Choi Yen Bach Truong Ilias Louis Kyratzis 《Electroanalysis》2012,24(5):1207-1211
In this work, GC electrodes modified with thick electrospun nanofibrous Nafion webs were characterized using scanning electron microscopy (SEM) and cyclic voltammetry (CV) and used for the extraction and electrochemical detection of cadmium by differential pulse voltammetry. Cadmium was detected after 10 min incubation at open circuit followed by anodic stripping using 60 s reduction at ?1.4 V. The electrode yielded well‐defined, undistorted and reproducible (RSD of 7.0 % based on 10 measurements) voltammetric response with two linear ranges from 0.1 to 3 µM (R2=0.994 ) and from 3 to 10 µM (R2=0.977) and a detection limit and sensitivity of 0.01 µM and 32 and 7.725 µA/µM for both linear portions of the curve respectively. 相似文献
977.
A speciation procedure has been established for the flame atomic absorption spectrometric determination of Cr(III) and Cr(VI) based on coprecipitation of Cr(III) by using praseodymium(III) hydroxide (Pr(OH)3) precipitate. In the presented system, Cr(III) was quantitatively (>95%) recovered at the pH range of 10.0?C12.0 on Pr(III) hydroxide, while the recoveries of Cr(VI) were below 10%. The method was applied to the determination of the total chromium after reduction of Cr(VI) to Cr(III) by using hydroxylamine hydrochloride. The concentration of Cr(VI) is calculated by difference of total chromium and Cr(III) levels. The analytical parameters including pH of the aqueous medium, amount of Pr(III), centrifugation speed, sample volume were optimized. The influences of matrix ions were also investigated. The method was validated by the analysis of TMDA 70 fortified lake water certified reference material. The method was applied to the speciation of chromium in water samples. 相似文献
978.
Mevlüt Bayrakc? ?eref Ertul Mustafa Y?lmaz 《Journal of inclusion phenomena and macrocyclic chemistry》2012,74(1-4):415-423
This article reports the solubilization of the practically water insoluble drug molecules such as nifedipine, niclosamide and furosemide by guest:host inclusion complexation with p-phosphonates calix[n]arenes as drug soluble agent. This complexation studies were carried out by using the phase solubility technique. From the obtained results, it was observed that the solubility of drug molecules was significantly increased in the presence of calix[n]arene host molecules. The increase in solubility of drugs by the calix[n]arene was most probably due to inclusion complexation between drug molecules and cavities of the calixarene skeleton similar to drug:cyclodextrin complexes. 相似文献
979.
980.
A 'Heat treatment aqueous two phase system' was employed for the first time to purify serine protease from kesinai (Streblus asper) leaves. In this study, introduction of heat treatment procedure in serine protease purification was investigated. In addition, the effects of different molecular weights of polyethylene glycol (PEG 4000, 6000 and 8000) at concentrations of 8, 16 and 21% (w/w) as well as salts (Na-citrate, MgSO? and K?HPO?) at concentrations of 12, 15, 18% (w/w) on serine protease partition behavior were studied. Optimum conditions for serine protease purification were achieved in the PEG-rich phase with composition of 16% PEG6000-15% MgSO?. Also, thermal treatment of kesinai leaves at 55 °C for 15 min resulted in higher purity and recovery yield compared to the non-heat treatment sample. Furthermore, this study investigated the effects of various concentrations of NaCl addition (2, 4, 6 and 8% w/w) and different pH (4, 7 and 9) on the optimization of the system to obtain high yields of the enzyme. The recovery of serine protease was significantly enhanced in the presence of 4% (w/w) of NaCl at pH 7.0. Based on this system, the purification factor was increased 14.4 fold and achieved a high yield of 96.7%. 相似文献