Nanostructured ZnO thin film for hydrogen peroxide sensing

A thin film of zinc oxide (ZnO) was deposited over the surface of a glass substrate by spray pyrolysis technique. To obtain ZnO thin film with nano-grains in this process, the substrate temperature was optimized and fixed at 503 K. Zinc acetate dihydrate was used as a precursor at an optimal concentration of 0.05 M. The structural and morphological properties of the film were investigated using X-ray Diffraction (XRD) and Field Emission–Scanning Electron Microscopy (FE–SEM), respectively. The peaks in the XRD pattern, confirmed the polycrystalline nature of the film with hexagonal wurtzite structure. Purity of the film has been confirmed through Energy Dispersive X-ray analysis (EDAX). Further the sensing behavior of the film was studied for various concentrations of hydrogen peroxide (H₂O₂) at optimized operating temperatures of 323 and 373 K. The nanostructured ZnO film exhibited good sensitivity in the range of 500 and rapid response–recovery time of 30–60 s, respectively, towards lower concentrations of H₂O₂.     

Optical properties of melamine based materials

The melamine based crystalline materials are synthesized. To determine the optical properties the transmittance and reflectance spectra are recorded. The absorption coefficient of the materials is calculated using the recorded transmittance values. From the absorption coefficient values the insulating behavior of all our studied materials is identified. In addition the direct bandgap transition nature of the materials is recognized from the absorption coefficient value. Tauc relation is used to determine the bandgap energy. The bandgap energy values suggest the dielectric nature of the materials and interpretation is given for high dielectric constant values.     

Solvent-free protocol for amide bond formation via trapping of nascent phosphazenes with carboxylic acids

A solvent-free synthesis of amides via the coupling of phosphazenes with carboxylic acids is reported. Increasing the rate of heating either by microwave irradiation or conventional heating results in multifold increase in the rate of amide bond formation. Synthesis of a library of amides including a potent antitumour candidate has been accomplished.     

1H and 13C NMR spectral assignments of some novel 2,4,6,8-tetraaryl-3,7-diazabicyclo[3.3.1]nonan-9-one derivatives

The (1)H and (13)C NMR spectra of 2,4,6,8-tetraaryl-3,7-diazabicyclo[3.3.1]nonan-9-ones (1-2), oximes (3-8) and O-benzyl oximes (9-12) were recorded. The chemical shifts were unambiguously assigned using 1D and 2D NMR spectral data. The results clearly indicate that the compounds exist in chair-boat conformation with equatorial and axial orientation of the aryl groups in the chair and boat forms, respectively. Since the molecules are flexible and dynamic in solution, the chair and boat forms are mutually interconvertible. In 3-12, because of the effect of oximation/oximination, all the protons in the heterobicyclic systems gave distinct signals except the benzylic protons of the boat form. In all synthesized compounds, the aryl group protons at C-6,8 are shielded by the aryl groups at C-2,4 and therefore appear in the lower frequency region than the aryl groups at C-2,4.     

Hydrothermal Preparation of Ni3S4/CoS2 Composite Electrocatalytic Materials for High Performance Counter Electrodes of Dye-Sensitized Solar Cells

Journal of Cluster Science - A facile one step synthetic hydrothermal route was used to fabricate the Pt free Ni3S4/CoS2 heterostructure counter electrode and study the photovoltaic characteristics...     

Catalytic oxidative conversion of alcohols, aldehydes and amines into nitriles using KI/I2-TBHP system

The oxidative conversion of alcohols, aldehydes and amines to give corresponding nitriles in excellent yields was easily achieved by the catalytic amount of KI or I₂ in combination with TBHP as an external oxidant. This non-transition metal catalyst is cost effective and provides easy work-up and separation of the product.     

Observation of subcellular structures of neurons by an illumination mode near-field optical microscope under an optical feedback control

We propose an illumination mode near-field optical microscope operated under an optical feedback for imaging biological specimens in their natural environment. For feedback control, rapidly varying evanescent signal has been generated over the sample surface. It has been found that evanescent signal can be profitably used as a control signal by utilizing its sample feature dependent discrimination sensitivity. Neurons have been successfully observed both in air and in liquid with a resolution well beyond the diffraction limit.     

Extraction chromatographic method for the separation of actinides and lanthanides using EDHBA grafted AXAD-16 polymer

A new extraction chromatographic method has been developed by grafting chloromethylated polymer support with 4-ethoxy-N,N-dihexylbutanamide (EDHBA), for the selective extraction of U(VI), Th(IV), La(III) and Nd(III) from highly acidic matrices. The developed grafted polymer has been characterized using ¹³C-CPMAS NMR spectroscopy, FT-NIR spectroscopy and also by CHN elemental analysis. The water regaining capacity of the grafted polymer is studied by TGA measurements and the active participation of the amide moiety towards metal ion complexation has been confirmed by Far IR spectroscopy. For the quantitative extraction of metal ions to the resin phase, various physio-chemical parameters are optimized by both static and dynamic methods. The developed amide grafted polymeric matrix shows good distribution ratio values even at high acidities, with the maximum metal sorption capacity values being 0.36, 0.69, 0.32 and 0.42 mmol g⁻¹ for U(VI), Th(IV), La(III) and Nd(III), respectively, at 6 M HNO₃ medium. The kinetics of metal ion phase equilibration is found to be moderately fast, with t_1/2 values of <6 min, for all the analytes of interest. The limits of analyte quantification (LOQ) using the developed method are in the range of 15-30 μg L⁻¹. Moreover, the sequential separation of the sorbed actinides and lanthanides could be achieved by first eluting with 100 mL of distilled water (for actinides) followed by elution with 20 mL of 0.1 M EDTA (for lanthanides). The selectivity behavior and the practical applicability of the developed resin are tested using synthetic low level nuclear reprocessing mixtures and also with monazite sand. The analytical data are within 3.8% relative standard deviation, reflecting the reproducibility and reliability of the developed method.