On Pointwise Convergence of q-Bernstein Operators and Their q-Derivatives

Pointwise convergence of q-Bernstein polynomials and their q-derivatives in the case of 0 < q < 1 is discussed. We study quantitative Voronovskaya type results for q-Bernstein polynomials and their q-derivatives. These theorems are given in terms of the modulus of continuity of q-derivative of f which is the main interest of this article. It is also shown that our results hold for continuous functions although those are given for two and three times continuously differentiable functions in classical case.     

The transfrmation of difluorocarbene into 3,3-diflurocyclopropene

The addition of difluorocarbene to benzobarrelene gives the syn and anti 1,2 mono-adducts. Heating of either of them at 200°C in hexadeuteriobenzene generates naphthalene and 3,3-difluorocyclopropene.     

Simultaneous determination of 5-hydroxymethylfurfural and patulin in apple juice by reversed-phase liquid chromatography.

A rapid, simple and economical method was described for the simultaneous determination of 5-hydroxymethylfurfural (HMF) and patulin in apple juice. The sample was extracted with ethyl acetate and the extract was then cleaned up by extraction with a sodium carbonate solution. Then HMF and patulin were determined by reversed-phase liquid chromatography using a C18 column and a photodiode array detector. HMF and patulin could be completely resolved by using the mixture water-acetonitrile (99:1, v/v) as the mobile phase with a flow rate of 1.0 ml/min. Mean recoveries of HMF ranged from 86% to 100% with an overall mean of 94%, that of patulin ranged from 94% to 125% with an overall mean of 103%, for different spiking levels. The limits of detection for HMF and patulin in apple juice were found to be < 0.01 mg/l and < 5 micrograms/l, respectively.     

Kinetics of crude oil combustion

In this research, thermal characterization and kinetics of Karakus crude oil in the presence of limestone matrix is investigated. Thermogravimetry (TG/DTG) is used to characterize the crude oil in the temperature range of 20-900°C, at 10°C min ^-1 heating rate using air flow rate of 20 mL min ^-1. In combustion with air, three distinct reaction regions were identified known as low temperature oxidation (LTO), fuel deposition (FD) and high temperature oxidation (HTO). Five different kinetic methods used to analyze the TG/DTG data to identify reaction parameters as activation energy and Arrhenius constant. On the other hand different f(α) models from literature were also applied to make comparison. It was observed that high temperature oxidation temperature (HTO) activation energy of Karakus crude oil is varied between 54.1 and 86.1 kJ mol ^-1, while low temperature oxidation temperature (LTO) is varied between 6.9 and 8.9 kJ mol ^-1.     

Enzymatically validated liquid chromatographic method for the determination of ascorbic and dehydroascorbic acids in fruit and vegetables

A liquid chromatographic method has been described for the determination of total vitamin C, ascorbic acid (AA) and dehydroascorbic acid (DHAA) in fruits and vegetables. The complete separation of AA and DHAA could be achieved on a C18 column using 0.2 M KH2PO4 (pH adjusted to 2.4 with H3PO4) as the mobile phase at a flow-rate of 0.5 ml/min. Since the detection sensitivity was poor for DHAA even at 210 nm, it was estimated as the difference between the total AA after DHAA reduction and AA content of the original sample, using dithiothreitol (DTT) as the precolumn reductant. The reaction times for the complete conversion of DHAA to AA at room temperatures were 150, 120, 90 and 75 min for 1, 2, 4 and 8 mmol DTT per mmol of DHAA, respectively. The percentage recovery ranged from 81.7 to 105.9. AA contents of some selected fruits and vegetables were analyzed comparatively by liquid chromatography and enzymatic assay to validate the method.     

Synthesis and Spectroscopic Characterization of Novel Aryl-Dithiofluorophosphonate Derivatives and X-Ray Studies of [(4-CH3OC6H4)(F)P(S)S−][PH4P+]

Abstract

Potassium and tetraphenylphosphonium salts of novel aryldithiofluorophosphonic acids were synthesized. Lawesson's Reagent was allowed to react with KF in acetonitrile to yield the potassium salt of p-methoxyphenyldithiofluorophosphonic acid. Treatment of the latter with tetraphenylphosphonium chloride resulted in the formation of the tetraphenylphosphonium salt. The structures of the compounds were elucidated by FTIR, ¹H, ¹³C, ¹⁹F, and ³¹P NMR spectroscopy as well as by ESI-mass spectrometry. The molecular and crystal structure of the tetraphenylphosphonium salt, determined by single crystal X-ray diffraction, is also presented.

Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements to view the free supplemental file.     

Multi-stage artificial neural network structure-based optimization of geothermal energy powered Kalina cycle

Journal of Thermal Analysis and Calorimetry - In this study, the geothermal energy powered Kalina cycle (GEP-KC) was optimized by using a multi-stage artificial neural network (ANN) analysis. The...     

Quantitative Mobility Spectrum Analysis for Determination of Electron and Magneto Transport Properties of Te-Doped GaSb

Resistivity, magnetoresistivity and Hall effect measurements in n-type Te-doped GaSb grown by the liquid encapsuled Czochralski technique are carried out as functions of temperature （35-350 K） and magnetic field （0-1.35 T）. The power law model is used to explain the temperature-dependent resistivity. The magnetic-field-dependent data are analysed using the quantitative mobility spectrum analysis technique. The effect of individual band parameters （nL, nr, μL, μr, p and μp） on both the electron and magneto transports have been discussed. The EL - Er energy separation between the L and conduction band edges is also derived.     

Investigation of electrochemical behavior and development of a validated adsorptive stripping square wave voltammetry method for 3-nitrotyrosine in human plasma and cerebrospinal fluid

An adsorptive stripping square wave voltammetric (AdSqW) method was developed for the determination of 3-nitrotyrosine (3-NT), a biomarker of in vivo oxidative damage in Alzheimer, ALS, Parkinson’s, cardiovascular diseases and cancer, in some biological fluids. Voltammetric measurements were performed in 0.30 M (pH 9.0) phosphate solution as supporting electrolyte, a reduction peak was observed at–0.487 V (vs. Ag/AgCl–3 M KCl) with a hanging mercury drop electrode by square wave voltammetry. Cyclic voltammetric measurements showed that the current was adsorption-controlled. LOD and LOQ values were as 0.25 and 1.5 nM, respectively, for the AdSqW method. 3-NT was determined in plasma and cerebrospinal fluid using AdSqW method, which allowed to work at low concentrations. Recovery value was measured as 96.3 ± 2.3%.