Brajesh Yadav - Academia.edu (original) (raw)

Papers by Brajesh Yadav

Buffalo Bulletin, 2017

The present study aimed to assess the metabolic status and milk composition of buffaloes with sub... more The present study aimed to assess the metabolic status and milk composition of buffaloes with subclinical mastitis. Forty buffaloes in early lactation from local buffalo dairy farms of Mathura district Uttar Pradesh (India) and instructional livestock farm complex of DUVASU, Mathura, found positive for subclinical mastitis at the quarter level by California mastitis test (CMT) (++ score) and high somatic cell counts (SCC) (>5 lakh cells per ml) were included in the present study. Another 20 clinically healthy buffaloes in early lactation and free of mastitis were used as healthy control group. Blood samples (5 mL) were collected from the both healthy and subclinical mastitic buffaloes and were used for estimation of serum metabolites including glucose, total cholesterol, triglycerides, total protein, albumin, urea, calcium (Ca), magnesium (Mg) and phosphorus (P). Further, milk samples were obtained from each affected quarter of buffaloes having subclinical mastitis as well as fro...

Thin Solid Films, 2006

Thin films of GaAs x N 1−x alloys were deposited by reactive rf magnetron sputtering of GaAs targ... more Thin films of GaAs x N 1−x alloys were deposited by reactive rf magnetron sputtering of GaAs target with a mixture of argon and nitrogen as the sputtering gas. Growth rate was found to decrease from ∼ 7 μm/h to ∼ 2 μm/h as the nitrogen content increased from 0% to 40%. XRD and TEM studies of the films reveal the presence of hexagonal GaN with a significant increase of the lattice parameters in a narrow range of composition of the sputtering gas (5-10% nitrogen), which is attributed to the incorporation of arsenic. The limited availability of nitrogen in the sputtering atmosphere is found to encourage the incorporation of arsenic in the alloy films. Optical absorption coefficient spectra of the films were obtained from reflection and transmission data. The effect of arsenic incorporation is seen in the optical absorption spectra of the films, which show a continuous shift of the absorption edge to lower energies with respect to that of gallium nitride.

Thin Solid Films, 2008

Polycrystalline GaN films were deposited on quartz and ZnO buffer layers over quartz by reactive ... more Polycrystalline GaN films were deposited on quartz and ZnO buffer layers over quartz by reactive sputtering of a GaAs target in 100% nitrogen at 550°C and 700°C. Micro-structural investigations of the films were carried out using high resolution X-ray diffraction, atomic force microscopy and Raman spectroscopy. GaN films deposited on ZnO buffer layers exhibit strongly preferred (0002) orientation of crystallites. In particular, the film deposited at 700°C on ZnO buffer layer over amorphous quartz substrate showed large crystallite size, both along and perpendicular to growth direction, strong and nearly complete c-axis orientation of crystallites with tilt of~2.5°and low value of micro-strain~2 × 10 − 3. The significant improvement in crystallinity and orientation of crystallites in the GaN film is attributed to the presence of the ZnO buffer layer on quartz substrate and its small lattice mismatch (1.8%) with GaN.

Journal of Applied Physics, 2007

GaN films have been deposited by radio frequency sputtering of a GaAs target with pure nitrogen. ... more GaN films have been deposited by radio frequency sputtering of a GaAs target with pure nitrogen. The growth, composition, and structure of the films deposited on quartz substrates have been studied by x-ray diffraction, transmission electron microscopy, and Raman spectroscopy. Films deposited below 300°C are amorphous and As rich. Above 300°C, polycrystalline, hexagonal GaN is formed, along with As rich amorphous phase, which reduces with increasing substrate temperature. At a substrate temperature of 700°C, GaN films, practically free of amorphous phase, and As ͑Ͻ0.5 at. % ͒ are formed. The preferred orientation depends strongly on the substrate temperature and is controlled by surface diffusion of adatoms during growth stage. Below 500°C, the surface diffusion between planes dominates and results in the ͑1011͒ preferred orientation. Above 500°C, the surface diffusion between grains takes over and results in ͑0002͒ preferred orientation.

Journal of Applied Physics, 2008

GaN films have been deposited by reactive rf sputtering of GaAs target in 100% nitrogen ambient o... more GaN films have been deposited by reactive rf sputtering of GaAs target in 100% nitrogen ambient on quartz substrates at different substrate temperatures ranging from room temperature to 700°C. A series of films, from arsenic-rich amorphous to nearly arsenic-free polycrystalline hexagonal GaN, has been obtained. The films have been characterized by phase modulated spectroscopic ellipsometry to obtain the optical parameters, viz., fundamental band gap, refractive index, and extinction coefficient, and to understand their dependence on composition and microstructure. A generalized optical dispersion model has been used to carry out the ellipsometric analysis for amorphous and polycrystalline GaN films and the variation of the optical parameters of the films has been studied as a function of substrate temperature. The refractive index values of polycrystalline films with preferred orientation of crystallites are slightly higher ͑2.2͒ compared to those for amorphous and randomly oriented films. The dominantly amorphous GaN film shows a band gap of 3.47 eV, which decreases to 3.37 eV for the strongly c-axis oriented polycrystalline film due to the reduction in amorphous phase content with increase in substrate temperature.

Advanced Computational Techniques in Electromagnetics, 2013

This paper adopted a new method of calculation of resonating frequency of an equilateral triangul... more This paper adopted a new method of calculation of resonating frequency of an equilateral triangular microstrip antenna using artificial neural network (ANN). The major advantage of an artificial neural network is proposed to predict the resonant frequency of an antenna as a function of its geometric parameters. The proposed neural model completely bypasses the required number of electromagnetic computation in training for design of such types of antenna. Thus resulting is an extremely fast solution and the ANN is ten times lower than that needed during antenna optimization process and resulting with high accuracy. The simulated software (Zealand IE3D version 12.0) based on method of moments has been used to generate data for training and validation set of ANN. The results of proposed ANN model are compared with the simulated results which were in very good agreement with the simulated results.

Journal of Alloys and Compounds, 2017

CrystEngComm

Self-aligned GaN nanorod assembly directly grown on metal foil substrates is very attractive for ... more Self-aligned GaN nanorod assembly directly grown on metal foil substrates is very attractive for developing flexible devices. In this report we have investigated the effect of growth temperature (500-700 ᵒC)...

Optical Materials, 2017

Abstract We have investigated the influence of growth temperature on the in-plane strain, structu... more Abstract We have investigated the influence of growth temperature on the in-plane strain, structural, optical and mechanical properties of heteroepitaxially grown GaN layers on sapphire (0001) substrate by laser molecular beam epitaxy (LMBE) technique in the temperature range 500–700 °C. The GaN epitaxial layers are found to have a large in-plane compressive stress of about 1 GPa for low growth temperatures but the strain drastically reduced in the layer grown at 700 °C. The nature of the in-plane strain has been analyzed using high resolution x-ray diffraction, atomic force microscopy (AFM), Raman spectroscopy and photoluminescence (PL) measurements. From AFM, a change in GaN growth mode from grain to island is observed at the high growth temperature above 600 °C. A blue shift of 20–30 meV in near band edge PL emission line has been noticed for the GaN layers containing the large in-plane strain. These observations indicate that the in-plane strain in the GaN layers is dominated by a biaxial strain. Using nanoindentation, it is found that the indentation hardness and Young's modulus of the GaN layers increases with increasing growth temperature. The results disclose the critical role of growth mode in determining the in-plane strain and mechanical properties of the GaN layers grown by LMBE technique.

Proceedings of the National Academy of Sciences India Section a, 1990

Physical chemistry chemical physics : PCCP, May 19, 2016

Correction for 'One step in situ synthesis of CeO2 nanoparticles grown on reduced graphene ox... more Correction for 'One step in situ synthesis of CeO2 nanoparticles grown on reduced graphene oxide as an excellent fluorescent and photocatalyst material under sunlight irradiation' by Animesh Kumar Ojha et al., Phys. Chem. Chem. Phys., 2015, DOI: .