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Semiconductive nanometer-size material ZnFe2O4 was synthesized by a solution combustion reaction of inorganic reagents of Zn(NO3)3. 6H2O, Fe(NO3)3.9H2O and Urea as a fuel. The process was a convenient, environment friendly, inexpensive and efficient preparation method for the ZnFe2O4 nanomaterial. Effects of the calcining temperature on the phase constituents characterized by TG-DTA, X-ray diffraction (XRD) was used to confirm the material structure, The as-prepared samples were further characterized by scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM). To depict the crystallite microstructure. Conductance responses of the nanocrystalline ZnFe2O4 thick film were measured by exposing the film to reducing gases like Acetone, Ethanol, Ammonia (NH3), Hydrogen (H2), Hydrogen sulphide (H2S), Chlorine (Cl2) and Liquefied petroleum gas (LPG). It was found that the sensors exhibited various sensing responses to these gases at different operating temperature. Furthermore, the sensor exhibited a fast response and a good recovery. The results demonstrated that ZnFe2O4 can be used as a new type of gas-sensing material which has a high sensitivity and good selectivity to Chlorine (CL2).

Manganese and Nickel doped Zinc Ferrite powder (Mn0.3Ni0.3Zn0.4Fe2O4) was synthesized by autocatalytic thermal decomposition technique. The average crystallite size in the material powder was found to be of 10 – 13 nm. Characterization techniques such as X-Ray diffraction studies, Transmission electron microscopy, Infra-Red spectroscopy, etc, were employed to study the average particle size, phase and composition of the ferrite. Thick films of Mn0.3Ni0.3Zn0.4Fe2O4 were prepared by screen printing technique. These films were observed to be sensitive to 10 ppm NH3 at room temperature. The effects of surface microstructure, operating temperature, gas concentrations, etc., on the gas response, selectivity, response and recovery times of the sensor in the presence of NH3 and other gases were studied and discussed.

Semiconductive nanometer-size material ZnCo2O4 was synthesized by a solution combustion reaction of inorganic reagents of Zn(NO3)3. 6H2O, Co(NO3)3.6H2O and glycine as a fuel. The process was a convenient, environment friendly, inexpensive and efficient preparation method for the ZnCo2O4 nanomaterial. The synthesized materials were characterized by TG/DTA, XRD, EDX, SEM, and TEM. Conductance responses of the nanocrystalline ZnCo2O4 thick film were measured by exposing the film to reducing gases like Acetone, Ethanol, Ammonia (NH3), Hydrogen (H2), Hydrogen sulphide (H2S), Chlorine (Cl2) and Liquefied petroleum gas (LPG). It was found that the sensors exhibited various sensing responses to these gases at different operating temperature. Furthermore, the sensor exhibited a fast response and a good recovery. The results demonstrated that ZnCo2O4 can be used as a new type of gas-sensing material which has a high sensitivity and good selectivity to Liquefied petroleum gas (LPG) at 100 ppm.

Nanostructured ZrO2 powder was synthesized by microwave assisted sol-gel method. The material was characterized by XRD and SEM techniques. X-Ray diffraction studies confirm that a combination of tetragonal and monoclinic zirconia nanoparticles is obtained by using microwave-assisted method. The nanopowder was calcined at an optimized temperature of 400 °C for 3 h. The prepared powder had crystalline size about 25 nm. Thick films of synthesized ZrO2 powder were prepared by screen printing technique. The gas sensing performances of these films for various gases were tested. Films showed highest response to H2 (50 ppm) gas at room temperature with poor responses to others (1000 ppm). The quick response and fast recovery are the main features of this sensor. The effects of microstructure, operating temperature and gas concentration on the gas response, selectivity, response time and recovery time of the sensor in the presence of H2 gas and others were studied and discussed.

Thick films of pure WO3 were prepared by screen-printing technique. The films were modified with Cu2+ by dipping them into an aqueous solution of copper chloride for different intervals of time and fired at 5500C for 30 min. The copper chloride would be transformed upon firing into copper oxide. The p-type CuO grains around n-type WO3 grains would form n- WO3/p-CuO heterojunctions. Upon exposure to H2S gas, the barrier height of n- WO3/p-CuO heterojunctions decreases markedly due to the chemical transformation of p-CuO into well conducting Cu2S, leading to a drastic change in resistance. These sensors were observed to operate at room temperature. An exceptional sensitivity was found to low concentrations (below threshold limit value = 10 ppm) of H2S gas at room temperature, and no cross sensitivity was observed even to high concentrations of other hazardous and polluting gases. The efforts have, therefore, been made to develop the heterocontact type gas sensor based on tin oxide surface-modified with cupric oxide. The effects of microstructure and surfactant concentration on the sensitivity, selectivity, response and recovery of the sensor in the presence of H2S gas were studied and discussed.

Thick films of (Ba0.1Sr0.9)(Sn0.5Ti0.5)O3 referred as BSST, were prepared by screen-printing technique. The preparation, characterization and gas sensing properties of pure and CuO-BSST mixed oxide semiconductors have been investigated. The mixed oxides were obtained by dipping the pure BSST thick films into 0.01 M aqueous solution of CuCl2, for different intervals of time. Pure BSST was observed to be less sensitive to H2S gas. However, mixed oxides of CuO and BSST were observed to be highly sensitive to H2S gas. Upon exposure to H2S gas, the barrier height of CuO-BSST intergranular regions decreases markedly due to the chemical transformation of CuO into well conducting CuS leading to a drastic decrease in resistance. The crucial gas response was found to H2S gas at room temperature and no cross sensitivity was observed to other hazardous and polluting gases. The effects of microstructure and doping concentration on the gas response, selectivity, response and recovery of the sensor in the presence of H2S gas were studied and discussed.

Thick films of pure and Al2O3 doped ZnO were prepared by screen printing technique. The gas sensing performance of these films for various gases was tested. Both pure and Al2O3-doped ZnO based sensors showed highest responses to H2 gas with poor response to former as compared to later. Al2O3 (3 wt %) doped ZnO thick films showed response to H2 gas as high as 143 while pure ZnO thick films showed poor (28) to H2 gas. Doped ZnO showed quick response and fast recovery to H2 gas. The quick response and fast recovery are the main features of this sensor. The effects of microstructure and additive concentration on the gas response, selectivity, response time and recovery time of the sensor in the presence of H2 gas were studied and discussed.

The preparation, characterization and gas sensing properties of pure and Fe2O3-ZnO mixed oxide semiconductors have been investigated. The mixed oxides were obtained by mixing ZnO and Fe2O3 in the proportion 1:1, 1:0.5 and 0.5:1. Pure ZnO was observed to be insensitive to NH3 gas. However, mixed oxides (with ZnO: Fe2O3 =1:0.5) were observed to be highly sensitive to ammonia gas. Upon exposure to NH3 gas, the barrier height of Fe2O3-ZnO intergranular regions decreases markedly due to the chemical transformation of Fe2O3 into well conducting ferric ammonium hydroxide leading to a drastic decrease in resistance. The crucial gas response was found to NH3 gas at 3500C and no cross response was observed to other hazardous and polluting gases. The effects of microstructure and doping concentration on the gas response, selectivity, response and recovery of the sensor in the presence of NH3 gas were studied and discussed.

The title compound was synthesized by standard routes of synthesis and its structure was established by spectral and X-ray diffraction studies. The compound crystallizes in the triclinic space group P-1 with unit cell parameters a = 10.4395(6), b = 11.9493(6), c = 13.8651(7), α = 108.958(5), b=103.089(5), ϒ = 97.885(4), Z=2. The crystal structure was solved by direct methods using single-crystal X-ray diffraction data collected at room temperature and refined by full-matrix least squares procedures to a final R-value of 0.0663 for 3330 observed reflections. In the title molecule, the tetrahydropyridine ring adopts a distorted boat conformation and both 4-nitro-phenyl substituents are in axial positions. The dihedral angle between the planes of the nitro-substituted rings is 45.5(1)o. The amino group and carbonyl O atom are involved in intramolecular hydrogen bonding and this interaction leads to the formation of a virtual-six membered ring. In the crystal, C-H…O intermolecular interactions stabilizes the crystal packing., European Chemical Bulletin, Vol 3, No 7 (2014): European Chemical Bulletin

In the title molecule, C19H17F3N2O2, the fused cyclohexene and pyran rings adopt sofa and flattened boat conformations, respectively. The four essentially planar atoms of the pyran ring [maximum deviation = 0.008 (2) Å] form a dihedral angle of 88.13 (9)° with the benzene ring. The F atoms of the trifluoromethyl group were refined as disordered over three sets of sites in a 0.507 (7):0.330 (7):0.163 (3) ratio. In the crystal, molecules are connected into inversion dimers via pairs of N—H...N hydrogen bonds and these dimers are further linked by N—H...O hydrogen bonds into a two-dimensional network parallel to (100).

In the title molecule, C19H18F3N3O, the dihydropyridine and cyclohexene rings both adopt sofa conformations. The five essentially planar atoms of the dihydropyridine ring [maximum deviation = 0.039 (2) Å] form a dihedral angle of 88.19 (8)° with the benzene ring. The F atoms of the trifluoromethyl group were refined as disordered over two sets of sites in a 0.840 (3):0.160 (3) ratio. In the crystal, N—H...O and N—H...N hydrogen bonds link molecules into a two-dimensional network parallel to (100).

In the title molecule, C24H29NO4, the central ring of the acridinedione system adopts a flat boat conformation and the four essentially planar atoms of this ring [maximum deviation = 0.001 (2) Å] form a dihedral angle of 85.99 (12)° with the benzene ring. The two outer rings of the acridinedione system adopt sofa conformations. In the crystal, O—H...O and N—H...O hydrogen bonds link the molecules, forming a two-dimensional network parallel to (100).

Most electrical distribution systems are incurring large losses as the loads are wide spread, inadequate reactive power compensation facilities and their improper control. A typical static VAR compensator consists of capacitor bank in binary sequential steps operated in conjunction with a thyristor controlled reactor of the smallest step size. This SVC facilitates stepless control of reactive power closely matching with load requirements so as to maintain power factor nearer to unity. This type of SVC-s requiring a appropriately controlled TCR. This paper deals with an air cored reactor suitable for distribution transformer of 3phase, 50Hz, Dy11, 11KV/433V, 125 KVA capacity. Air cored reactors are designed, built, tested and operated in conjunction with capacitor bank in five binary sequential steps. It is established how the delta connected TCR minimizes the harmonic components and the operating range for various electrical quantities as a function of firing angle is investigated. In particular firing angle v/s line & phase currents, D.C. components, THD-s, active and reactive powers, odd and even triplen harmonics, dominant characteristic harmonics are all investigated and range of firing angle is fixed for satisfactory operation. The harmonic spectra for phase and line quantities at specified firing angles are given. In case the TCR is operated within the bound specified in this paper established through simulation studies are yielding the best possible operating condition particularly free from all dominant harmonics.

Department of Chemistry, Shivaji University, Kolhapur-416 004, Maharashtra, India E-mail : m_ deshmukh1@rediffmail.com Manuscript received 17 June 2008, revised 12 April 2010, accepted 12 April 2010 The nitrogen and sulphur containing compounds are well known for their vital role in medicinal chemistry. Here, we report the synthesis of 2-hydrazido-1,4-benzothiazine (2) from 2-carbethoxy 1,4-benzothiazine-3-(1H)-one (1) and hydrazine hydrate which then treated with acetyl acetone, ethyl acetoacetate, cyanoethylacetate to give substituted 2-(benzothiazine-3-one-2-yl-oxo)-3,5-dimethyl pyrazole (2a), 1-(benzothiazine-3-one-2-yl-oxo)-3-methyl pyrazole-5-one (2b) and (1-benzothiazine-3-one-2-yl-oxo)-3-amino pyrazole-5-one (2c) respectively under microwave irradiation. Further, the reaction or 2 with phenyl isothiocyanate under microwave irradiation yielded 1-(benzothiazolyl-oxo)-4-phenyl thiosemicarbazide (2d) which was subsequently cyclised with cone. H2SO4 and dil. NaOH to give targeted 2-(benzothiazin-3-one-2-yl)-5-anilino-1, 3,4-oxadiazole (2e) and 1-phenyl-2-[benzothiazine-3(1H)-one-2-yl]-5-mercapto-1 ,3,5-triazole (2f) respectively.

In the title compound, C(11)H(12)FNO, the dihedral angle between the prop-2-en-1-one group and the benzene ring is 19.33 (6)°. The configuration of the keto group with respect to the olefinic double bond is s-cis. In the crystal, the mol-ecules form dimers through aromatic π-π stacking inter-actions [centroid-centroid distance = 3.667 (1) Å] and are linked via C-H⋯O inter-actions into chains along the b axis.

A convenient green chemistry method through one pot four component tandem synthesis of hexahydroquinoline via enaminone intermediate using dimedone, ammonium acetate, aryl aldehydes and malononitrile has been described in aqueous media without the use of any external catalyst. The excess of ammonium acetate used acts as a reagent as well as catalyst. The incorporation of water as solvent along with eradication of external catalyst renders the protocol to comply with the green chemistry aspects. Shorter reaction time, high atom economy, easy work up and purification of products by non-chromatographic method are the crucial features of this methodology. The crystal structure of hexahydroquinoline basically shaped by chromatographic free selective reaction was determined by single crystal X-ray diffraction analysis.