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Undoped and Ni-doped ZnO thin films were grown on glass substrates at 460 °C using the spray pyrolysis method. All samples were characterized by means of certain physical techniques. First, X-ray diffraction analysis revealed that undoped ZnO as well as Ni-doped ZnO thin films crystallized in the hexagonal wurtzite structure. Second, the optical bandgap value seems depending on Ni content and the optical transmittance coefficient was determined to be more than 90%. Finally, the effect of Ni doping on ethanol sensing response was also investigated. An improvement in response is obtained for ZnO:25%Ni sample. [ABSTRACT FROM AUTHOR]

Copper sulfide (CuS2) has been prepared by spray pyrolysis process. Structural and morphological properties of prepared sample were investigated by XRD and AFM. The X-ray diffraction showed that the structure of this film is cubic. The film surface was homogenous and dense. The UV absorbance and reflectance spectra show a high absorbance with gap energy of 1.87 eV estimated by Tauc's model. The photoconductive studies reveal that the photocurrent versus light intensity and polarization follows a power low and linear trend, respectively. In addition, the CuS2 film had excellent stability. AC conductivity (Gac) reveals the semiconductor behavior and the activation energy is estimated to be 0.5 eV. It is also obvious that the conductance AC follows jonscher's universal power law. The exponent "s" decreases with temperature increase, showing that the conduction phenomena is related to Correlated Barrier Hopping (CBH). The imaginary and real impedance parts are plotted in Nyquist diagrams and an equivalent circuit is deduced. Consequently, the prepared CuS2 film is suitable for optoelectronic applications, such as solar cells and photodetector. [ABSTRACT FROM AUTHOR]

In2S3 thin films have been deposited onto glass substrates at 340 °C using an inexpensive spray pyrolysis method (CSP) via the reaction between high purity indium chloride and thiourea. Structural, optical and photoconductive properties of thin films have been investigated by adjusting S/In molar ratio. The X-ray diffraction results revealed that In2S3 films are polycrystalline and exhibited a cubic structure. The optical and morphological properties are discussed. The photoconductive performances were conducted by DC electrical characterization. The best photosensitivity was obtained for the film matching S/In = 2 molar ratio. In addition, photocurrent versus light intensity and bias voltage follows a power law and linear trend, respectively. Furthermore, some critical parameters such as responsivity and detectivity were determined to evaluate photosensitive properties of In2S3 thin films. [ABSTRACT FROM AUTHOR]

This paper reports the effect of the substrate temperature of sprayed In2S3 material on the sensing response to ethanol. Glass substrates have been the supports of In2S3 thin films elaborated by spray pyrolysis technique. The growth has been made at a substrate temperature in the range 300–500 °C and the S/In molar ratio was set to 2. The morphology and microstructure of the obtained layers were depicted by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM) and Raman spectroscopy. Ethanol vapor dynamic response was evaluated at a working temperature ranging from 250 to 400 °C by DC electrical characterization. The best response towards ethanol is obtained for the film deposited at 380 °C substrate temperature. Moreover, the oxygen adsorption heats of films were also evaluated. [ABSTRACT FROM AUTHOR]

Pb-, Zn- and Cd-bearing particles from the flotation tailing heaps of Jebel Ressas mine are carried by wind and water toward the surrounding agricultural areas. These crop-producing areas are made of fersialitic soils and developed on carbonated bedrock. The risk of ecotoxicity depends on the bioavailability fraction of metals which is closely related to their physicochemical and biological environment. The objective of this study was to assess the contamination of the soils surrounding the waste dumps and to estimate the bioavailable fraction of metals present in these soils. The flotation tailings display big amounts of Zn, Pb and Cd, averaging 7.11 %, 2.30 % and 290 mg kg, respectively. The concentrations found in soils reach 6.3 % Zn, 2.3 % Pb and 290 mg kg Cd. Analyses of the samples taken between surface and bedrock show that Pb and Zn may reach concentrations as high as 900 mg kg 2 m below surface. Simple extraction tests show that with deionized water only Zn is mobile, with 0.02-0.03 mmol l released from soil. The mobilization of contaminants by organic acids, secreted by plants in the rhizosphere, is potentially higher than that achieved in the presence of percolating waters. [ABSTRACT FROM AUTHOR]

Apoanagyrus ( Epidinocarsis) lopezi De Santis is an endoparasitoid used in the biological control of the cassava mealybug Phenacoccus manihoti Matile-Ferrero in Africa. The response of naive and mated females of A. lopezi to odors from cassava plant (var. Zanaga), parasitized or unparasitized mealybugs, and plant–mealybug host complexes with or without feeding hosts was investigated in a Y-tube olfactometer. Dual-choice tests revealed that mealybug-infested plants and mealybug-damaged plants were the major sources of volatiles that attract female parasitoids to the microhabitat of its hosts. The emission of volatile chemicals appears not to be limited to the infested plant part but to occur systemically throughout the plant. On their own, unparasitized mealybugs were more attractive than uninfested plants or parasitized mealybugs alone. Parasitization of P. manihoti by A. lopezi decreased the response of parasitoids to mealybugs or mealybug–plant complexes. Plants infested with unparasitized hosts attracted more female parasitoids than plants infested with parasitized mealybugs. These results indicate that, in the long-range host-searching process, females of A. lopezi respond mainly to mealybug-induced synomones, and specific host-derived cues play a minor role. [ABSTRACT FROM AUTHOR]