Oxidative Deprotection of Cyclic Acetals and Trimethylsilyl Ethers by γγ-Picolinium Chlorochromate Under Nonaqueous Conditions

Deprotection of cyclic acetals and oxidative desilylation of trimethylsilyl ethers into the corresponding carbonyl compounds with -picolinium chlorochromate (-PCC) under nonaqueous conditions at room temperature is described. Oxidation of aldehydes to carboxylic acids was not observed in any case.     

Thermal evaluation of a heat pipe working with n-pentane-acetone and n-pentane-methanol binary mixtures

Journal of Thermal Analysis and Calorimetry - In the present study, a set of experiments were accomplished to appraise the thermal performance and heat transfer of n-pentane-acetone and...     

SYNTHESIS OF SOME BICYCLIC THIAZOLO AND THIAZEPINOPYRIMIDINE DERIVATIVES

Thiazolo 3 a–c and oxothialo 5 a–b pyrimidine compounds were synthesized by a simple one-pot condensation reaction of the pyrimidine derivative i 1a and 1,2-dibromoethane i 2 or 2-bromopropanoic acid 4 . In a similar way the thiazepinopyrimidine compounds 7 (a–b) were synthesized by reaction of 1b and 1,4-dichlorobutane 6 in dimethylformamide under reflux condition. The yields of products following recrystallization were of the order of 60–80%.     

Influence of base fluid,temperature, and concentration on the thermophysical properties of hybrid nanofluids of alumina–ferrofluid: experimental data,modeling through enhanced ANN,ANFIS, and curve fitting

Journal of Thermal Analysis and Calorimetry - Recently, the suspension of hybrid nanoparticles in conventional fluids has been investigated as a technique for improving the thermophysical...     

Numerical analysis of dual variable of conductivity in bioconvection flow of Carreau–Yasuda nanofluid containing gyrotactic motile microorganisms over a porous medium

Journal of Thermal Analysis and Calorimetry - The increasing need of the modern era of technology for better ways to increase the heat transfer performance of thermal systems has made nanoliquids...     

Towards insight into properties and stabilities of complexes of ozone with CO2, CS2 and SCO species

The MP2 method in combination with the aug-cc-pVXZ (X = D and T) basis set has been carried out to examine the complexes between O₃ and isostructure species of CO₂, CS₂ and SCO. Two, two and four minima have been located on the potential energy surfaces of O₃–CO₂, O₃–CS₂ and O₃–SCO complexes, respectively. The results reveal that the stabilization of complexes should be in the order O₃–CS₂ > O₃–SCO > O₃–CO₂.     

Measurement of water activities of alanine + tri-potassium citrate + water system at temperatures between 293.15 and 313 K—Experimental and modeling

Water activity measurements by isopiestic method have been carried out on the aqueous solutions of alanine + tri-potassium citrate (K₃Cit) over a range of temperatures at atmospheric pressure. From these measurements, values of the vapor pressure of solutions were determined. The effect of temperature on the vapor–liquid equilibrium of alanine + K₃Cit + H₂O systems has been studied. The experimental water activities have been correlated successfully with the segment-based local composition Wilson and NRTL models. The agreement between the correlations and the experimental data is good.     

Circular ripple formation on the silicon wafer surface after interaction with linearly polarized femtosecond laser pulses in air and water environments

Ultrashort laser pulse interaction with the surface of silicon wafer in air and water environments is investigated. Ti:sapphire laser with 40 femtosecond laser pulses at 790 nm and 10 Hz repetition rate was used. The ablation threshold of the silicon surface in the air was determined to be about 0.28 J cm^?2. The surface morphology was studied by using scanning electron microscope images. The size of the regular ripples formed in the air environment is a little smaller than the laser wavelength. Due to the nonlinear interaction and self-focusing before the target, the ripples size reduced to nearly a half of the laser wavelength in the water. Moreover, the spikes’ structure formation and their diameter in air and water were studied. Two regimes for spike formation in water are proposed that can explain the anomalous decrease of the spikes’ diameter in higher fluence. During the interaction of single linearly polarized femtosecond laser pulse with the surface, an irregular ripple formation that called circular ripple is observed. This structure which is a result of radiation pressure implies to the surface by the end of the pulse. A new physical model for interpretation of the circular ripples formation based on the ponderomotive force of an ultrashort pulse laser is proposed which can predict the size of the circular ripples. The calculated results are in accordance with our experimental findings.