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221.
Serkan Elçin Murat Muzaffer İlhan Hasalettin Deligöz 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):259-267
In this study, the synthesis and characterization of two new upper rim functionalized azocalix[4]arene dyes have been obtained by coupling calix[4]arene with different diazo compounds of 3,5-dicarboxyaniline and 4-aminobenzene sulphon amide. The characterization of these dyes has been carried out by elemental analysis, FT-IR and 1H NMR spectra. The effect of varying dielectric constants of solvents on the absorption spectra of azocalix[4]arenes (1, 2, 3, 4) and commercial Isolan Gelb SGL (T) have been examined by UV–Vis spectrophotometer. These azocalix[4]arene dyes have also been used for dyeing textile fibers like cotton, wool, acetate, polyester and polyamide fibers. Their dyeing and fastness properties have also been discussed. 相似文献
222.
Sinem?Erden?GulebaglanEmail author Sirri?Batuhan?Kalkan Serkan?Sirt Enver?Metin?Kendirlik Afif?Siddiki 《The European Physical Journal B - Condensed Matter and Complex Systems》2014,87(3):72
In this work we investigate an unusual transport phenomenon observed in two-dimensional electron gas under integer quantum Hall effect conditions. Our calculations are based on the screening theory, using a semi-analytical model. The transport anomalies are dip and overshoot effects, where the Hall resistance decreases (or increases) unexpectedly at the quantized resistance plateaus intervals. We report on our numerical findings of the dip effect in the Hall resistance, considering GaAs/AlGaAs heterostructures in which we investigated the effect under different experimental conditions. We show that, similar to overshoot, the amplitude of the dip effect is strongly influenced by the edge reconstruction due to electrostatics. It is observed that the steep potential variation close to the physical boundaries of the sample results in narrower incompressible strips, hence, the experimental observation of the dip effect is limited by the properties of these current carrying strips. By performing standard Hall resistance measurements on gate defined narrow samples, we demonstrate that the predictions of the screening theory is in well agreement with our experimental findings. 相似文献
223.
Two novel p-tert-butylcalix[4]arene-based chiral organocatalysts derived from l-proline have been developed to catalyze direct aldol reactions between cyclohexanone and aromatic aldehydes in water. Under the optimal conditions, high yields (up to 95%), enantioselectivities (up to 90%), and moderate diastereoselectivities (up to 65:35) were obtained. Considering the catalytic inefficiency of sole proline for the aldol reaction in water, these results clearly display the enormous effect of the hydrophobic part of calix[4]arene of compound A. 相似文献
224.
Esra Öztürk Nilgun Kalaycioglu Ozpozan Serkan Dayan 《Journal of Thermal Analysis and Calorimetry》2014,117(2):573-578
Mn4+ doped and Dy3+, Tm3+ co-doped MgAl2Si2O8-based phosphors were prepared by conventional solid state reaction at 1,300 °C. They were characterized by thermogravimetry, differential thermal analysis, X-ray powder diffraction, photoluminescence, and scanning electron microscopy. The luminescence mechanism of the phosphors, which showed broad red emission bands in the range of 600–715 nm and had a different maximum intensity when activated by UV illumination, was discussed. Such a red emission can be attributed to the 2E → 4A2 transitions of Mn4+. 相似文献
225.
Soner Buytoz Fethi Dagdelen Serkan Islak Mediha Kok Durmus Kir Ercan Ercan 《Journal of Thermal Analysis and Calorimetry》2014,117(3):1277-1283
Copper matrix with an individual addition of TiC particles was prepared by means of powder metallurgy and hot pressing process, and the effect of TiC addition on microstructure, thermal properties, and electrical conductivity of Cu–TiC composites was investigated. The TiC quantity was changed as 1, 3, 5, 10, and 15 Cu (in mass%), and Cu–TiC powder mixtures were hot-pressed for 4 min at 700 °C under an applied pressure of 50 MPa. Microstructure studies revealed that TiC particles were distributed uniformly in the Cu matrix. Thermal Analysis result showed that there were two exothermic peaks and with rising TiC rate, oxidation amount of Cu composite decreased. With the increasing addition of TiC, hardness of composites changed between 58.6 HV0.1 and 87.8 HV0.1. The highest electrical conductivity for Cu–TiC composites was obtained in the Cu-1 mass% TiC composite, with approximately 81.2 % IACS. 相似文献
226.
Ozcan Kocyigit Serkan Erdemir Mustafa Yilmaz 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(1-2):137-147
This study contains the synthesis of silica gel-immobilized calix[4]arene derivative (TR-CL[4]P) as a new sorbent and its sorption studies towards Cu (II) ion in aqueous solution. The aldehyde pointed calix[4]arene derivative 5 was synthesized and then it was immobilized onto 3-aminopropilsilica gel (APS). In batch sorption experiments, the experimental results showed that TR-CL[4]P is effective sorbent towards Cu (II) ion. Therefore, the effect of solution pH, sorption time, temperature and initial metal ion concentration onto Cu (II) sorption was investigated. Maximum Cu(II) removal was obtained at 30?°C, 30?min and pH 6.0 for TR-CL[4]P and the batch sorption capacity was found as 17.8?mg/g. The characteristics of the sorption process for Cu (II) ion were evaluated by using the Langmuir, Freundlich and Dubinin–Radushkevich (D–R) adsorption isotherms. Also, thermodynamic parameters, i.e., ΔG, ΔS, and ΔH were calculated for the system. 相似文献
227.
In the present study, the synthesis and liquid phase extraction properties towards some amino acid methylesters and amino alcohols of Schiff base and amino alcohol substituted calix[4]arene are reported. The Schiff base substituted calix[4]arene 5 has been synthesized via condensation reaction involving 5,17-diformyl-11,23-di-tert-butyl-25,27-di[3-(4-formylphenoxy)propoxy]-26,28 dihydroxycalix[4]arene 4 and (R)-(?)-2-phenylglycine methyl ester in CHCl3:MeOH. To give the amino alcohol substituted calix[4]arene 6, the synthesized chiral compound 5 was reduced by LiAlH4. The new chiral Schiff base and amino alcohol derivatives of calix[4]arene have been characterized by a combination of FT-IR, 1H NMR, 13C NMR, FAB-MS and elemental analysis. Also, the extraction behaviors of 5 and 6 towards some selected amino acid methylesters and amino alcohols have been studied by liquid–liquid extraction. 相似文献
228.
The concept of mean residual life is one of the most important characteristics that has been widely used in dynamic reliability analysis. It is a useful tool for investigating ageing properties of technical systems. In this paper, we define and study three different mean residual life functions for k-out-of-n:G system with a single cold standby component. In particular, we obtain explicit expressions for the corresponding functions using distributions of order statistics. We also provide some stochastic ordering results associated with the lifetime of a system. We illustrate the results for various lifetime distributions. 相似文献
229.
In this paper a general van Est type isomorphism is proved. The isomorphism is between the Lie algebra cohomology of a bicrossed sum Lie algebra and the Hopf cyclic cohomology of its Hopf algebra. We first prove a one to one correspondence between stable-anti-Yetter-Drinfeld (SAYD) modules over the total Lie algebra and those modules over the associated Hopf algebra. In contrast to the non-general case done in our previous work, here the van Est isomorphism is proved at the first level of a natural spectral sequence, rather than at the level of complexes. It is proved that the Connes-Moscovici Hopf algebras do not admit any finite dimensional SAYD modules except the unique one-dimensional one found by Connes-Moscovici in 1998. This is done by extending our techniques to work with the infinite dimensional Lie algebra of formal vector fields. At the end, the one to one correspondence is applied to construct a highly nontrivial four dimensional SAYD module over the Schwarzian Hopf algebra. We then illustrate the whole theory on this example. Finally explicit representative cocycles of the cohomology classes for this example are calculated. 相似文献
230.
Saniye Özcan Ülfet Erdoğan Uzunoğlu Serkan Levent Nafiz Öncü Can 《Journal of separation science》2023,46(17):2300228
Lumacaftor is a transmembrane conductance regulator potentiator drug, prescribed for the treatment of cystic fibrosis in patients who are homozygous for the F508del mutation. Quantitation of lumacaftor besides its degradation products and ivacaftor was achieved on a fused-core silica particle column packed with pentafluorophenylpropyl stationary phase (Ascentis Express F5, 2.7 μm particle size 100 mm × 4.6 mm; Supelco) using gradient elution (A: 0.1% [v/v] formic acid in water, B: 0.1% [v/v] formic acid in acetonitrile [the mobile phase pH 2.5]). A constant flow rate at 1 mL/min was applied, and the detection was realized using a photodiode array detector set at 216 nm. The pseudo tablet formulation of the lumacaftor/ivacaftor fixed-dose combination preparation, namely, Orkambi®, was prepared in vitro and used for the analytical performance validation and method application studies. In addition, five novel degradation products, four of which even have no Chemical Abstracts Services registry number, were identified using high-resolution mass spectrometry instrument, and their possible mechanisms of formation were proposed. According to current literature, this paper can be regarded as the most comprehensive liquid chromatographic study on lumacaftor determination, among its counterparts. 相似文献