Effects of pH on the morphology of iron oxides synthesized under gamma-irradiation

Summary 190, Kinshasa XI, Kinshasa, République Démocratique du C     

Synthesis of nanocomposite, (CdxZn1-x)S by gamma-irradiation in an aqueous system

Gamma-irradiation has been applied to synthesize the nanocomposite semiconductor constituted of zinc and cadmium sulfide Cd_1-xZn_xS ultra fine particles at room temperature by utilizing homogeneous release of S^2– ions from the decomposition of sodium thiosulfate. The structure, morphology, size and optical properties of that compound have been studied by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet-visible spectrometer (UV-visible). The product obtained from irradiated solutions containing zinc ions, cadmium ions and the sulfur source has been characterized as a composite of (Cd_xZn_1-x)S, with spherical morphology and with a diameter of average size of about 5.3 nm. The possible mechanism of formation of the composite is proposed.The financial support of Shanghai Science and Technology Foundation through No. 0252nm 095 is gratefully acknowledged.The authors would thank the staff of Shanghai Applied Radiation Institute of Shanghai University for their valuable contributions.     

Synthesis of nanocomposite, (CdxZn1-x)S by gamma-irradiation in an aqueous system

Gamma-irradiation has been applied to synthesize the nanocomposite semiconductor constituted of zinc and cadmium sulfide Cd_1-xZn_xS ultra fine particles at room temperature by utilizing homogeneous release of S^2– ions from the decomposition of sodium thiosulfate. The structure, morphology, size and optical properties of that compound have been studied by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and ultraviolet-visible spectrometer (UV-visible). The product obtained from irradiated solutions containing zinc ions, cadmium ions and the sulfur source has been characterized as a composite of (Cd_xZn_1-x)S, with spherical morphology and with a diameter of average size of about 5.3 nm. The possible mechanism of formation of the composite is proposed.The financial support of Shanghai Science and Technology Foundation through No. 0252nm 095 is gratefully acknowledged.The authors would thank the staff of Shanghai Applied Radiation Institute of Shanghai University for their valuable contributions.     

Synthesis of nanocrystalline zinc sulfide in a non-aqueous system by gamma-irradiation

Summary Gamma-irradiation has been applied to synthesize nanocrystalline ZnS with average size of 38 nm in a non-aqueous system at room temperature by utilizing homogeneous release of S^2- ions from the decomposition of carbon disulfide under γ-irradiation. The structure, morphology, size and optical properties have been studied by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectrometer (UV-visible). The product containing zinc ions and the sulfur source has been characterized as β-ZnS, sphalerite phase, with spherical morphology and with a diameter average size of about 38 nm.The possible mechanism of formation of the product is suggested in accord with the experiment.     

Pyrethroid and Etofenprox Resistance in Anopheles gambiae and Anopheles coluzzii from Vegetable Farms in Yaoundé, Cameroon: Dynamics,Intensity and Molecular Basis

Previous studies have indicated widespread insecticide resistance in malaria vector populations from Cameroon. However, the intensity of this resistance and underlying mechanisms are poorly known. Therefore, we conducted three cross-sectional resistance surveys between April 2018 and October 2019, using the revised World Health Organization protocol, which includes resistance incidences and intensity assessments. Field-collected Anopheles gambiae s.l. populations from Nkolondom, Nkolbisson and Ekié vegetable farms in the city of Yaoundé were tested with deltamethrin, permethrin, alpha-cypermethrin and etofenprox, using 1× insecticide diagnostic concentrations for resistance incidence, then 5× and 10× concentrations for resistance intensity. Subsamples were analyzed for species identification and the detection of resistance-associated molecular markers using TaqMan® qPCR assays. In Nkolbisson, both An. coluzzii (96%) and An. gambiae s.s. (4%) were found together, whereas only An. gambiae s.s. was present in Nkolondom, and only An. coluzzii was present in Ekié. All three populations were resistant to the four insecticides (<75% mortality rates―MR1×), with intensity generally fluctuating over the time between mod-erate (<98%―MR5×; ≥98%―MR10×) and high (76–97%―MR10×). The kdr L995F, L995S, and N1570Y, and the Ace-1 G280S-resistant alleles were found in An. gambiae from Nkolondom, at 73%, 1%, 16% and 13% frequencies, respectively, whereas only the kdr L995F was found in An. gambiae s.s. from Nkolbisson at a 50% frequency. In An. coluzzii from Nkolbisson and Ekié, we detected only the kdr L995F allele at 65% and 60% frequencies, respectively. Furthermore, expression levels of Cyp6m2, Cyp9k1, and Gste2 metabolic genes were highly upregulated (over fivefold) in Nkolondom and Nkolbisson. Pyrethroid and etofenprox-based vector control interventions may be jeopardized in the prospected areas, due to high resistance intensity, with multiple mechanisms in An. gambiae s.s. and An. coluzzii.