Magnetoelectric effect in cobalt ferrite-barium titanate composites and their electrical properties

CoFe₂O₄-BaTiO₃ composites were prepared using conventional ceramic double sintering process with various compositions. Presence of two phases in the composites was confirmed using X-ray diffraction. The dc resistivity and thermoemf as a function of temperature in the temperature range 300 K to 600 K were measured. Variation of dielectric constant (ɛ′) with frequency in the range 100 Hz to 1 MHz and also with temperature at a fixed frequency of 1 kHz was studied. The ac conductivity was derived from dielectric constant (ɛ′) and loss tangent (tan δ). The nature of conduction is discussed on the basis of small polaron hopping model. The static value of magnetoelectric conversion factor has been studied as a function of magnetic field.     

Oxidation of propane to acrylic acid and acetic acid over alkaline earth-doped Mo-V-Sb-Ox catalysts

Alkaline earth metal (Mg, Ca, Sr and Ba)-doped Mo-V-Sb-Ox catalysts, prepared by a dry-up method, have been investigated for their catalytic performance in the oxidation of propane under different reaction conditions. The catalysts have been characterized by N2 adsorption-desorption, temperature-programmed desorption (TPD) of NH3, SEM and XRD. Influence of water vapor on the catalytic performance, particularly on the selectivities to acetic acid and acrylic acid, has also been studied. The selectivity to acrylic acid was improved significantly by the doping of alkaline earth metals to Mo-V-Sb-Ox catalysts. The surface acidic sites of the catalyst decreased with the doping of the catalyst with alkaline earth metals, which ultimately was found to be beneficial for obtaining high selectivity to acrylic acid. The catalytic activity and product selectivities were found to be influenced by the reaction temperature, C3H8/O2 ratio and space velocity. A significant improvement in the selectivity to acrylic acid has also been observed by the addition of water vapor in the feed of propane and oxygen in the oxidation of propane.     

Synthesis and characterization of crosslinked chitosan formed by γ irradiation in the presence of carbontetrachloride as a sensitizer

Synthesis of crosslinked chitosan using γ irradiation in the presence of carbon tetrachloride as a sensitizer is carried out. The resultant crosslinked product, which is yellow in color, is characterized by elemental analysis, which shows the presence of chlorine. Crosslinked chitosan on hydrolysis with alkali results in the formation of another product that retains the crosslinked structure but does not have chlorine in it. Gel formatting characteristics of both these products have been studied. The crosslinked chitosan and its hydrolysis product are further characterized by various physical methods such as X‐ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FTIR), and thermogravimetry. Based on the results, a probable mechanism of crosslinking whereby chitosan chains are crosslinked by a >CCl₂ group is suggested. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3897–3909, 2004     

Effect of N 2 + ion implantation on the oxidation behaviour of Fe50Ni50 alloy

The high temperature oxidation behavior of Fe₅₀Ni₅₀ alloy foils implanted with 100 KeV N₂ ⁺ ions at a different dose values is studied by using the technique of conversion electron Mössbauer spectroscopy (CEMS). It has been shown that the implanted foils exhibit considerable adherence of scales and higher oxidation resistance as compared to the virgin foils. This excessive adherence of scales to the surface and higher resistance to oxidation of implanted samples is attributed to nickel enrichment in the surface layers. Various oxides of Fe, Ni and Fe?Ni are identified from the hyperfine interaction parameters of the corresponding CEMS spectra and also from x-ray diffraction measurements.     

A computational study of microsolvation effect on ethylene glycol by density functional method

This study focuses on the conformational analysis of ethylene glycol-(water)n (n=1-3) complex by using density functional theory method and the basis set 6-311++G*. Different conformers are reported and the basis set superposition error corrected total energy is -306.767 5171, -383.221 3135, and -459.694 1528 for lowest energy conformer with 1, 2, and 3 water molecules, respectively, with corresponding binding energy -7.75, -15.43, and -36.28 kcal/mol. On applying many-body analysis it has been found that relaxation energy, two-body, three-body energy have significant contribution to the binding energy for ethylene glycol-(water)3 complex whereas four-body energies are negligible. The most stable conformers of ethylene glycol-(water)n complex are the cyclic structures in which water molecules bridge between the two hydroxyl group of ethylene glycol.     

Vapor–liquid equilibria and excess molar volumes of diethylamine(1) + acetone(2) and diethylamine(1) + acetonitrile(2) binary systems

Isothermal vapor–liquid equilibrium (VLE) data for diethylamine(1)+acetone(2) and diethylamine(1)+acetonitrile(2) binary systems were obtained at 323.15 K by dynamic method. Excess molar volumes at 298.15 K for these systems were measured by a dilution dilatometer. VLE data have been checked for thermodynamic consistency and correlated by Wilson, NRTL and UNIQUAC equations. UNIFAC group interaction parameters for CH₂NH---CH₃CO and CH₂NH---CH₃CN pairs are also obtained from the experimental VLE data.     

Nanocrystalline In2O3-based H2S sensors operable at low temperatures

Nanocrystalline In(2)O(3)-based solid solutions, with different concentration of Co, with cubic structure were successfully prepared by a simple route. The as-prepared materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The indirect heating structure sensors based on pure and doped In(2)O(3) as sensitive materials were fabricated on an alumna tube with Au electrodes and gas-sensing properties of the sensor elements were measured as a function of concentration of dopant, operating temperature and concentrations of the test gases. The results showed that In(2)O(3) had high response towards H(2)S gas at an operating temperature 150 degrees C, while 2.5 wt.% Co-doped In(2)O(3) sensor exhibited enhance response and selectivity to H(2)S at rather lower operating temperature. Incorporation of platinum further improved the response, selectivity and response time towards H(2)S. Platinum incorporated 2.5 wt.% Co-doped In(2)O(3) (Pt: 0.5 wt.%) was able to detect 10-100 ppm of H(2)S in air at an operating temperature of 100 degrees C. The selectivity of the sensor elements for H(2)S against liquefied petroleum gas (LPG), NH(3) and H(2) gases was studied. The improved gas-sensing properties can mainly be attributed to the selectivity to oxidation of H(2)S and noble metal additive sensitization.     

Green Synthesis of Pyrazole and Oxazole Derivatives

New intermediate 3‐methyl‐5‐oxopyrazol propanenitrile was synthesized by one pot three component reactions using ethyl cyanoacetate, hydrazine hydrate, and ethyl acetoacetate and was used for the synthesis of new oxazole and pyrazole derivatives. All reactions were carried out using eco‐friendly solvents and without catalyst.     

Sorption of uranium from alkaline waste onto radiation grafted phosphoryl-g-Teflon matrix

High energy ⁶⁰Co γ-radiation was used to graft glycidylmethacrylate onto Teflon scrap through mutual radiation grafting technique. The epoxy ring of grafted polyGMA chains were later converted to U selective phosphoryl group, chemically. The grafted matrix was used as solid–liquid adsorbent of uranium from alkaline waste solution. More than 98% recovery of uranium from alkaline waste (~pH 8) solution was achieved. The effect of grafting extent on adsorption kinetics was also investigated. The selectivity of uranium extraction over other fission products was established. The uptake of other fission products was <5% for equilibration time of ~1 h.