Volume 233, Issue 9

CdTe/CdSe multilayer heterostructures thin films were prepared by thermal evaporation method. The CdTe/CdSe layers deposited on glass substrate and effects of annealing temperature on optical and structural properties of thin films were investigated. The XRD analysis revealed that CdTe and CdSe were in cubic (111) and hexagonal (100) forms. By increasing the annealing temperature, intensity of XRD peaks increased for multilayer heterostructures. Band alignment in heterostructures of CdTe/CdSe was of type II. Energy band gaps values for CdTe/CdSe multilayer heterostructures increased with respect to bulk compounds. During emission, red and blue shifts are observed in visible region in photoluminescence spectrum of CdTe/CdSe samples. Due to better crystallinity of multilayer thin film, 1LO, 2LO and 3LO phonon modes were observed in Raman spectrum.

In this study the synthesis of bi-phase nanoparticles of Fe 1.46 Zn 0.5 La 0.04 Cu 0.5 O 4 (FZLCs) ceramics were first carried out by Sol-gel method and then nanocomposites of FZLCs with polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG) and polyethylene oxide (PEO) were prepared by one-pot blending technique. XRD, FT-IR, TG/DTA and SEM techniques were applied for complete characterization of composites. Rheological and dielectric properties of all nanocomposites were studied in detail for their comparative performance. TGA results reveal the highly thermal stability for all nanocomposites in this order i.e. FLZCs/PEO > FLZCs/PVA > FZLCs/PVP > FZLCs/PEG. Rheological properties show that these materials are rigid, pseudo plastic and non-Newtonian in nature. The increase in values for storage modulus (G′) and loss modulus (G′′) with increasing angular frequency owed to the shear thinning behavior of these nanocomposites. Dielectric properties show good agreement to that of energy storage substances which means that these materials have potential to be applied in storage devices.

In this work, we systematically investigate the impacts of electron-donor based on Triphenylamine (TPA). The Geometry structure, energy levels, light-harvesting ability and ultraviolet-visible absorption spectra were calculated by using Density Functional Theory (DFT) and Time-Dependent-DFT. The electron injection rate of the TPA-N(CH 3 ) 2 based dyes has 0.71 eV for high among the dye sensitizer. The First and Second order Hyperpolarizability of the 11.95 × 10 −30 e.s.u and 12195.54 a.u, respectively for TPA-N(CH 3 ) 2 based dye. The calculated absorption spectra were showed in the ultra-violet visible region for power conversion region. The study reveals that the electron transfer character of TPA-N(CH 3 ) 2 based dyes can be made suitable for applications in Dye-Sensitized Solar Cells.

The development of biocompatible, cost effective and more efficient materials to control or inhibit the growth of microorganisms in necessary to fight against resistant microbes. Here, we demonstrate the synthesis of nickel oxide-incorporated polyaniline/polyvinyl alcohol (PANI/PVA/NiOx) composite material by single-step polymerization and its application as antibacterial agent. The composite films were characterized using UV-visible spectroscopy (UV-Vis), Thermogravimetric analysis (TGA), Fourier Transform Infrared spectroscopy (FTIR), X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). UV-Vis spectra revealed the enhancement in absorption properties of PANI/PVA/NiOx with optimum 5% incorporation of NiOx. TGA results indicated slightly enhanced thermal stability of the PANI/PVA/NiOx composite film as compared to PANI/PVA. FTIR spectra for composites revealed the existence of NiOx in polymers. However the crystallinity of PANI/PVA was not much affected. The antibacterial activity of the prepared composites was examined against four different gram negative bacteria, Salmonella, Shigella, Pseudomonas and Escherichia coli (E. coli). The composite exhibited excellent antibacterial activity against E. coli, Salmonella and Shigella while pseudomonas showed some resistance. Based on the results, PANI/PVA/ NiOx (5%) composite showed the highest activity against the tested bacterial strains, thus showing its potential to be used as an effective antibacterial agent.

The presence of heavy metals in water causes serious problems and their treatment before incorporating into the water body is a challenge for researchers. The present study was conducted to compare the sorption study of Ni (II) using silica gel, amberlite IR-120 and sawdust of mulberry wood in batch system under the influence of pH, initial Ni (II) concentration and contact time. It was observed that sorption process was depending upon pH and maximum sorption was achieved at pH 7.0. Kinetic data were well fitted into pseudo-second order kinetic model due to high R 2 values and closeness of experimental sorption capacity and calculated sorption capacity of pseudo-second order. Isotherms study showed that Langmuir is one of the most suitable choices to explain sorption data due to high R 2 values. The monolayer sorption capacities of silica gel, amberlite IR-120 and sawdust were found to be 33.33, 25.19, and 33.67 mg g −1 , respectively. Desorption study revealed that NaCl is one of the most appropriate desorbent. It may be concluded from this study that sawdust is a suitable sorbent due to low cost, abundant availability and recycling of the materials for further study.

Isothermal solvent evaporation method was employed to grow Undeuterated Hydrazonium L-tartrate (HLT) single crystals using water:methanol (5:1) solution as a solvent. The proton and carbon positions of HLT have been revealed by 1 H and 13 C NMR spectrum, respectively. The energy emission behaviour of HLT were analysed by photoluminescence spectrum. The nonlinear refractive index (n 2 ), nonlinear absorption coefficient ( β ) and third order nonlinear susceptibility ( χ 3 ) of HLT single crystal were determined by adapting Z-scan technique. Quantum chemical calculations on HLT was carried out by DFT using B3LYP/6-311++G(d,p) basis set. The predicted first hyperpolarizability of HLT is found to be 1.09 times greater than that of urea and suggests that HLT could be an attractive material for NLO applications. The predicted HOMO-LUMO energies of HLT confirmed that charge transfers occur within the molecule. The molecular bond strength and stability of the title compound were analysed by employing NBO analysis. The other molecular properties such as Mulliken atomic charge, ESP map, thermodynamic functions and perturbation theory energy have also been investigated. These investigations have been carried out for the first time, to the best our knowledge, in order to study the nonlinear optical properties of HLT and to enhance its usefulness for NLO applications.

Nanotechnology is an art for application and handling of materials at very small scales i.e. 1–100 nm. The materials at this scale exhibit significantly different properties compared to same materials at larger scales. There are so many physical and chemical methods for the synthesis of nanoscale materials but the most appropriate are the ones that synthesize materials using green chemistry eco-friendly techniques. Recently, the collaboration between nanotechnology and biology has opened up new horizons of nanobiotechnology that integrates the use of biological materials in a number of biochemical and biophysical processes. This approach has significantly boosted up nanoparticles (NPs) production without employing harsh and toxic conditions and chemicals. This review is aimed to provide an outline of latest developments in synthesis of NPs through biotic entities and their potential applications.

In the present study, the potential of synthesized mixed cellulose, alginate and hydroxyapatite beads for the efficient removal of Ni (II) and Cu (II) ions from aqueous solutions was investigated. Cellulose, alginate and hydroxyapatite are known for their individual adsorption capacity. Beads were prepared in different ratios of these materials. The prepared beads were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) and thermogravimetric analysis (TGA). FTIR and XRD analysis showed characteristic peaks assigned to cellulose, alginate and hydroxyapatite. Thermal stability was observed to increase with increase of hydroxyapatite percentage in beads. SEM images showed increased surface porosity and roughness with the increase of cellulose percentage. The prepared beads were used for the removal of Ni (II) and Cu (II) ions from aqueous solutions and the process was optimized with respect to pH, contact time, adsorbent dose and initial concentration of metal ions. The values of the coefficient of determination (R 2 ) of the Langmuir and Freundlich adsorption model indicated that the adsorbed Cu (II) and Ni (II) ions form monolayer coverage on the adsorbent surface. In kinetic analysis, Pseudo-second-order model fitted the kinetic experimental data well, as it showed high R 2 value; above 0.9990.