Synthesis and photoluminescence studies on catalytically grown Zn1 – xMnxS nanowires

Zn1 – xMnxS alloy nanowires with composition (x = 0.0, 0.1 and 0.3) have been successfully synthesized by a simple thermal evaporation on the silicon substrate coated with a gold film of 2 nm thickness. X-ray powder diffraction measurements reveal that as synthesized products were hexagonal wurtzite structure. The as grown nanowires have been investigated by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive Analysis of X-rays (EDAX) and photoluminescence studies. The results reveal that the as grown nanowires consist of Zn, Mn, and S material and diameter ranging from 70 - 150 nm with lengths up to several tens of micrometers. Photoluminescence studies on Zn1 – xMnxS exhibited peaks at 600 and 613 nm for x = 0.1 and 0.3 respectively. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/1053

Magnetic and dielectric properties of BiFeO3 nanoparticles

Single crystalline nano-sized multiferroic BiFeO3 (BFO) powders were synthesized through simple chemical co-precipitation method using polyethylene glycol (PEG) as capping agent. We obtained pure phase BiFeO3 powder by controlling pHand calcination temperature. From X-ray diffraction studies the nanoparticles were unambiguously identified to have a rhombohedrally distorted perovskite structure belonging to the space group of R3c. No secondary phases were detected. It indicates single phase structure. EDX spectra indicated the appearance of three elements Bi, Fe, O in 1:1:3. From the UV-Vis diffuse reflectance spectrum, the absorption cut-off wavelength of the BFO sample is around 558nm corresponding to the energy band gap of 2.2 eV. The size (60-70 nm) and morphology of the nanoparticles have been analyzed using transmission electron microscopy (TEM).   Linear M−H behaviour and slight hysteresis at lower magnetic field is observed for BiFeO3 nanoparticles from Vibrating sample magnetometer studies. It indicates weak ferromagnetic behaviour at room temperature. From dielectric studies, the conductivity value is calculated from the relation s = L/RbA Sm-1 and it is around 7.2 x 10-9 S/m

Fabrication Of ZnxCd1 – xSe Nanowires By CVD Process And Photoluminescence Studies

ZnxCd1 – xSe alloy nanowires with composition x = 0.2, 0.5 have been successfully synthesized by a simple thermal evaporation on the silicon substrate coated with a gold film of 20 Å thickness. The as-synthesized alloy nanowires, 70 - 150 nm in diameter and several tens of micrometer in length. The nanowires are single crystalline revealed from Transmission electron microscopy (TEM) and XRD measurement. The structure of ZnxCd1 – xSe nanowires are hexagonal wurtzite with [01-10] growth direction. Energy gap of the ZnxCd1 – xSe nanowires are determined from micro photoluminescence measurements. The energy gap increases with increasing Zn concentration. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/954

Effect of Mg Doping on the Structural and Optical Properties of CdS Nanoparticles Synthesized by co-Precipitation Method

Cd1 – xMgxS (x = 0.00, 0.05, 0.10, 0.15 and 0.20) nanoparticles were synthesized by co-precipitation method for the first time. Compositional, morphological, structural and optical studies of the as prepared samples were carried out by X-ray diffraction (XRD), Energy dispersive analysis of X-rays (EDAX), Scanning electron microscopy (SEM), Diffuse reflectance spectroscopy (DRS) and Photoluminescence (PL) techniques. XRD studies revealed the structural phase transition from cubic to hexagonal and increase in the average grain size of the nanoparticles (lie in the range 1.4 nm to 2.8 nm) with increasing Mg content. EDAX spectra rules out the existence of impurities in the samples. Bandgap widening was observed in all the samples compared to bulk CdS (2.42 eV). Decrease in bandgap (3.02 eV to 2.54 eV), luminescence quenching and red shift of luminescence peak position were observed with increasing Mg in Cd1 – xMgxS. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3028

Transcriptome profiling, physiological, and biochemical analyses provide new insights towards drought stress response in sugar maple (Acer saccharum Marshall) saplings

Sugar maple (Acer saccharum Marshall) is a temperate tree species in the northeastern parts of the United States and is economically important for its hardwood and syrup production. Sugar maple trees are highly vulnerable to changing climatic conditions, especially drought, so understanding the physiological, biochemical, and molecular responses is critical. The sugar maple saplings were subjected to drought stress for 7, 14, and 21 days and physiological data collected at 7, 14, and 21 days after stress (DAS) showed significantly reduced chlorophyll and Normalized Difference Vegetation Index with increasing drought stress time. The drought stress-induced biochemical changes revealed a higher accumulation of malondialdehyde, proline, and peroxidase activity in response to drought stress. Transcriptome analysis identified a total of 14,099 differentially expressed genes (DEGs); 328 were common among all stress periods. Among the DEGs, transcription factors (including NAC, HSF, ZFPs, GRFs, and ERF), chloroplast-related and stress-responsive genes such as peroxidases, membrane transporters, kinases, and protein detoxifiers were predominant. GO enrichment and KEGG pathway analysis revealed significantly enriched processes related to protein phosphorylation, transmembrane transport, nucleic acids, and metabolic, secondary metabolite biosynthesis pathways, circadian rhythm-plant, and carotenoid biosynthesis in response to drought stress. Time-series transcriptomic analysis revealed changes in gene regulation patterns in eight different clusters, and pathway analysis by individual clusters revealed a hub of stress-responsive pathways. In addition, qRT-PCR validation of selected DEGs revealed that the expression patterns were consistent with transcriptome analysis. The results from this study provide insights into the dynamics of physiological, biochemical, and gene responses to progressive drought stress and reveal the important stress-adaptive mechanisms of sugar maple saplings in response to drought stress

Synthesis of Fluorinated Bent-Core Mesogens (BCMs) Containing the 1,2,4-Oxadiazole Ring

New fluorinated bent-core mesogens containing the 1,2,4-oxadiazole or 1,2,4-triazole nucleus have been synthesized taking advantage of the ANRORC (Addition of Nucleophile, Ring-Opening, Ring-Closure) reactivity of 5-perfluoroalkyl-1,2,4-oxadiazoles. Physical state changes of the obtained compounds were characterized through DSC, POM, and SAXS. Besides the formation of a smectic mesophase, a novel behavior as organic molecular glass was evidenced for some 1,2,4-oxadiazole derivatives