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The effect of salt on the associative behavior of intramolecular aggregates obtained from poly(ethylene glycol)-based amphiphilic comb-like polymers in aqueous medium at pH 6.2 has been investigated by surface tension, fluorescence probe, dynamic light-scattering, and viscometry techniques. Results reveal that the addition of salt screens the electrostatic repulsion between the charges along the polymer backbone in the aggregates and consequently (1) reduces the surface activity at the air/water interface, (2) leads to the contraction of the polymer backbone, and (3) reduces the hydrodynamic sizes of the aggregates. In contrast, the hydrophobicity of the aggregates remains unperturbed. [Copyright &y& Elsevier]

Abstract: Nanocrystalline Sr2FeMoO6 (SFMO) belonging to the group of double perovskite oxides, was prepared by the sol–gel citrate method. The structural and microstructural characterization has been carried out with the help of X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. XRD of Sr2Fe1−x Ni x MoO6 (SFNMO) shows the formation of solid solution with average grain size of about 40nm. A comparative study of gas sensing behaviour of Sr2FeMoO6 and Sr2Fe1−x Ni x MoO6 with reducing gases like hydrogen sulfide (H2S), liquid petroleum gas (LPG), hydrogen (H2), ethanol (C2H5OH) and carbon monoxide (CO) were also discussed. The sensitivity is calculated by measuring the change the resistance of the sensor material in the presence of gas. Among the different composition of x (x =0.2, 0.3, 0.4, 0.5), Sr2Fe0.6Ni0.4MoO6 (x =0.4) shows better response to H2S gas at 260°C. Incorporation of palladium (Pd) improves the gas response, selectivity, response time and reduced the operating temperature from 260 to 220°C for H2S gas. [Copyright &y& Elsevier]

Abstract: In this paper, the structural and gas sensing properties of nanocrystalline La0.7Pb0.3Fe0.4Ni0.6O3 was prepared by a sol–gel citrate method. The structural characteristics of the material were studied by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD pattern shows a nanocrystalline solid solution of La0.7Pb0.3Fe0.4Ni0.6O3 with a perovskite phase. The gas sensing properties were studied for different reducing gases such as H2S, ethanol, CO and LPG. The La0.7Pb0.3Fe0.4Ni0.6O3 powder showed large response to H2S gas at an operating temperature 250°C. Further improvement in response was achieved by the addition of 0.5wt% Pd to La0.7Pb0.3Fe0.4Ni0.6O3. The sensor showed a good response to 150ppm H2S gas at an operating temperature 200°C. [Copyright &y& Elsevier]

Abstract: The thick-film semiconductor sensor for liquid petroleum gas (LPG) detection was fabricated using a mixed WO3-based sensor. We present the characterization of both their structural properties by means of XRD measurements and the electrical characteristics by using gas-sensing properties. The sensing characteristics such as sensitivity, working range, cross-sensitivity and response time were studied by using nanosized WO3-based mixed with different metal oxides (SnO2, TiO2 and In2O3) and doped with noble metals (Au, Pd and Pt). The WO3-based mixed with 5wt.% In2O3 and 0.5wt.% Pd showed the higher sensing characteristic at low concentration of LPG sensor at an operating temperature 225°C. [Copyright &y& Elsevier]