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161.
The summability process introduced by Bell (Proc Am Math Soc 38: 548–552, 1973) is a more general and also weaker method than ordinary convergence. Recent studies have demonstrated that using this convergence in classical approximation theory provides many advantages. In this paper, we study the summability process to approximate a function and its derivatives by means of a wider class of linear operators than a family of positive linear operators. Our results improve not only Baskakov’s idea in (Mat Zametki 13: 785–794, 1973) but also the Korovkin theory based on positive linear operators. In order to verify this we display a specific sequence of approximating operators by plotting their graphs. 相似文献
162.
Ali Zoungrana Mehmet Çakmakci İsmail Hakkı Zengin Özlem İnoğlu Harun Elcik 《Chemical Papers》2016,70(9):1185-1195
In this study, the treatability of metal-plating waste water by modified direct contact membrane distillation (DCMD) at different temperature differences (ΔT = 30°C, 40°C, 50°C, and 55°C was investigated. Two different hydrophobic membranes made of poly(tetrafluoroethylene) (PTFE) and poly(vinylidene fluoride) (PVDF) having different pore sizes (0.22 μm and 0.45 μm) were used. The results indicated that conductivity, COD, sulphate, copper, and nickel could be successfully removed by modified DCMD. The rejection efficiencies for conductivity, COD, and sulphate were 99%, 86%, and 99%, respectively. Copper rejection was effective with both membranes while nickel concentration was below the limit of detection in the effluent. It was found that the pollutant rejection efficiency was affected by the raw water characteristics, membrane properties, and influent heating temperatures. In addition to the water quality parameters, the flux was measured to evaluate membrane performance. A high flux was obtained at 65°C (ΔT = 55°C) with 0.45 μm pore size PTFE membrane (24.1 L m?2 h?1) and with PVDF membrane (17.1 L m?2 h?1). The flux was mainly affected by temperature and membrane properties. As a result, modified DCMD and all the membranes used in this study were effective for the treatment of metal-plating waste water. 相似文献
163.
A convenient procedure for the preparation of oxazole and pyrrole derivatives is described. 2-Amino-1,3-oxazol-2-ones 3a,b were first synthesized from the cyclocondensation reactions of cyanamide (2) with 4-ethoxycarbonyl-5-aryl-2,3-furandione 1a,b, and then new pyrrol-2-ones 5 were synthesized from the reaction of the compounds 3 with various aromatic amines 4. 相似文献
164.
In this study, we have performed the preparation of over-oxidized poly(3,4-ethylenedioxythiophene) nanofibers modified pencil graphite electrode (Ox-PEDOT-nf/PGE) to develop a selective and sensitive voltammetric uric acid (UA) sensor. It was noted that the over-oxidation potential and time had a prominent effect on the UA response of the Ox-PEDOT-nf/PGE. Characterizations of PEDOT-nf/PGE and Ox-PEDOT-nf/PGE have been performed by cyclic voltammetry, electrochemical impedance spectroscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and Raman spectroscopy. The highest voltammetric response of UA was obtained at pH 2.0. A linear relationship between the concentration of UA and oxidation peak currents was observed in the concentration range of 0.01–20.0 μM. The detection limit (1.3 nM according to S/N = 3) and reproducibility (RSD: 4.6 % for N:10) have also been determined. The effects of different substances on the determination of UA have been investigated. A very high peak separation value of 423 mV was obtained between UA and ascorbic acid which is the major interfering substance for UA. The use of Ox-PEDOT-nf/PGE has been successfully tested in the determination of UA in human blood serum and urine samples for the first time in the literature. 相似文献
165.
İnce İskender Yıldırım Yeliz Güler Günnur Medine Emin İlker Ballıca Gülşah Kuşdemir Bekir Cem Göker Erdem 《Journal of Radioanalytical and Nuclear Chemistry》2020,324(1):71-85
The aim of the present research was to formulate and characterize radioiodinated folic acid-chitosan conjugated thymoquinone nanoparticles (FATQCSNPs) and to increase targeting ability on ovarian cancer cell. The dose of drug-loading into the FATQCSNPs and the amount of folic acid on the FATQCSNPs surface were determined as a 20.0?±?1% and 46.0?±?0.5%, respectively. Cell viabilities (%) determined on SKOV-3 and Caco-2 cells for 48 h. TQ, TQCS and FATQCS were very cytotoxic with lower IC50 values on both cell lines. At specific-activity-dependent incorporation study, the incorporation efficiencies of 131I-FATQCSNPs was higher than that of 131I-TQ on SKOV3 cell lines.
相似文献166.
In this study a kind of poly(azomethine-urethane); (E)-4-((2 hydroxyphenylimino) methyl)-2-methoxyphenyl 6-acetamidohexylcarbamate (HDI-co-3-DHB-2-AP) was prepared as in the literature and employed as a new fluorescent probe for detection of Cd(II) concentration. The photoluminescence (PL) measurements were carried out in the presence of several kinds of heavy metals. HDI-co-3-DHB-2-AP gave a linearly and highly stable response against Cd(II) as decreasing a new emission peak at 562 nm. Possible interferences of other ions were found too low. Detection limit of the sensor was found as 8.86?×?10?4?mol?L?1. Resultantly, HDI-co-3- DHB-2-AP could be effectively used as an optical Cd(II) sensor. 相似文献
167.
?smail Aslan 《Applied mathematics and computation》2011,217(12):6013-6017
By means of the two distinct methods, the Exp-function method and the extended (G′/G)-expansion method, we successfully performed an analytic study on the (2 + 1)-dimensional Schwarzian Korteweg-de Vries equation. We exhibited its further closed form traveling wave solutions which reduce to solitary and periodic waves. New rational solutions are also revealed. 相似文献
168.
Senem Şanli İsmail M. Palabiyik Nurullah Şanli Zeynep B. Guzel-Seydim Güleren Alsancak 《Journal of Analytical Chemistry》2011,66(9):838-847
The simple, rapid and sensitive liquid chromatographic separation of five macrolides (tilmicosin, erythromycin, tylosin, roxithromycin
and josamycin) widely used in food producing animals was developed. Response surface methodology was used as an optimization
method of mobile phase, column temperature and pH to provide the best resolution of these analytes. The separation was performed
by using an end-capped X-Terra RP-18 column (250 × 4.6 mm I.D × 5 m) with an isocratic system of 15 mM hydrochloric acid (pH
2.5)-acetonitrile as the mobile phase at a temperature of 30°C and flow-rate of 1.0 mL/min. The suitability of the method
for multi-residue determination of the macrolides is demonstrated by the analysis of milk samples spiked with tylosin. Roxithromycin
was used as internal standard. The recovery of tylosin was quite good as 90.8%. The limit of quantification and detection
limit were 0.024 and 0.007 μg/mL, respectively. The method was successfully applied to determination of macrolides at levels
below the maximum concentration legally allowed in milk samples. 相似文献
169.
Serpil Demir?smail Özdemir Bekir ÇetinkayaHakan Arslan Don VanDerveer 《Polyhedron》2011,30(1):195-200
The new well-defined and air-stable ortho-xylyl-linked N-heterocyclic carbene (NHC) Pd complexes (2a-d) have been synthesized and characterized by elemental analysis, 1H NMR, 13C NMR, IR spectroscopy, and single crystal X-ray diffraction studies. The palladium atom in the complex 2a lies on a crystallographic mirror plane and can be described as having a square-planar coordination environment with the carbene atoms of the benzimidazole rings of the ligand occupying two coordination sites in cis positions. Two further coordination sites are occupied by chloride ligands. The benzimidazole rings are connected to each other by an ortho-xylyl bridge. The catalytic activity of these palladium complexes has been tested in the coupling reactions of various N-containing substrates with bromobenzene. A preliminary catalytic study shows that the bis(NHC)-Pd complexes are highly active in the Buchwald-Hartwig amination reaction. 相似文献
170.
R?za Bayrak Mahmut Durmu? ?smail De?irmencio?lu 《Journal of organometallic chemistry》2011,696(23):3807-3815
The synthesis and characterization of new peripherally tetra-3,5-dimethylpyrazole-1-methoxy substituted metal-free (4), zinc (5), nickel (6), cobalt (7), copper (8) and lead (9) phthalocyanines are described for the first time in this study. The photophysical (fluorescence quantum yields and fluorescence lifetimes) and photochemical (photodegradation and singlet oxygen quantum yields) properties of metal-free (4), zinc (5) and lead (9) phthalocyanines are studied in dimethylsulfoxide (DMSO). Nickel (6), cobalt (7) and copper (8) phthalocyanines (6-8) did not evaluate for this purpose due to transition metal and paramagnetic behavior of central metals in the phthalocyanine cavity. The fluorescence quenching behavior of metal-free (4), zinc (5) and lead (9) phthalocyanines are also investigated. The fluorescence emissions of these phthalocyanines are effectively quenched by 1,4-benzoquinone in DMSO. 相似文献