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Number of results: 15
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Abstract

Transparent Al doped ZnO nanocrystalline films with a crystallite size less than 19 nm are obtained by spray pyrolysis. Band gap increases monotonically from 3.16 to 3.31 eV with increasing aluminum dopant up to 1.56 at.% facilitating increasing width of a transmission window in addition to the band gap tuning of 4.74% which compares favorably well with literature. UV emission with continuously increasing intensity is obtained which reflects on the good crystalline quality of the films. Also the defect emissions are suppressed remarkably as the dopant Al concentration increases in ZnO. The band gap tuning by quite small increment in dopant amount makes the present films, much attractive for the fabrication of light emitting devices with a much sought-for benefit of large area fabrication. FESEM shows the surface is granular with grain size lying in the range of 20–35 nm and EDX confirms the presence of Al in the doped samples.

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Authors and Affiliations

N. Kumar
A. Srivastava
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Abstract

In this paper we introduce a novel encryption technique, which we call PixSel. This technique uses images in place of literature as the book cipher’s key. Conventional book ciphers possess an unwieldy ciphertext enlargement, creating ciphertexts multiple times the length of the plaintext. As well, there is often the issue of a given book not containing the necessary material for the encipherment of some plaintexts. Wesought to rectify these nuisances with PixSel, possessing a typical ciphertext enlargement of merely 1% to 20% for text. UsingPixSel, there are also no limitations on encipherable data type, given a suitable image.
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Authors and Affiliations

Shumay Mykel
Srivastava Gautam
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Abstract

The paper projects the potential of agricultural waste Saraca indica leaf powder (SILP) in biosorbing chromium from aqueous system. The influence of pH, contact time, metal concentration, biomass dosage and particle size on the selectivity of the removal process was investigated. The maximum sorption efficiency of SILP for Cr(lll): 85.23% and Cr(VI): 89.67%was found to be pH dependent giving optimum sorption at pH 6.5 and 2.5 respectively. The adsorption process fitted well to both Freundlich and Langmuir isotherms. Morphological changes observed in Scanning Electron Micrographs ofmetal treated biomass confirm the existence of biosorption phenomenon. Fourier Transform Infra-red Spectrometry confirms that amino acid-Cr interactions contribute a significant role in the biosorption of chromium using target leafpowder. The successful applications of easily abundant agricultural waste SILP, as a biosorbent have potential for a low technological pretreatment step, prior to economically not viable high-tech chemical treatments for the removal of Cr from water bodies.
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Authors and Affiliations

Pritee Goyal
Parul Sharma
Shalini Srivastava
M.M. Srivastava
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Abstract

In this research work, a Cylindrical Surrounding Double-Gate (CSDG) MOSFET design in a stacked-Dual Metal Gate (DMG) architecture has been proposed to incorporate the ability of gate metal variation in channel field formation. Further, the internal gate's threshold voltage (VTH1) could be reduced compared to the external gate (VTH2) by arranging the gate metal work-function in Double Gate devices. Therefore, a device design of CSDG MOSFET has been realized to instigate the effect of Dual Metal Gate (DMG) stack architecture in the CSDG device. The comparison of device simulation shown optimized electric field and surface potential profile. The gradual decrease of metal work function towards the drain also improves the Drain Induced Barrier Lowering (DIBL) and subthreshold characteristics. The physics-based analysis of gate stack CSDG MOSFET that operates in saturation involving the analogy of cylindrical dual metal gates has been considered to evaluate the performance improvements. The insights obtained from the results using the gate-stack dual metal structure of CSDG are quite promising, which can serve as a guide to further reduce the threshold voltage roll-off, suppress the Hot Carrier Effects (HCEs) and Short Channel Effects (SCEs).
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Authors and Affiliations

Abha Dargar
1
Viranjay M. Srivastava
1

  1. Department of Electronic Engineering, Howard College, University of KwaZulu-Natal, Durban, 4041, South Africa
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Abstract

The development of economic and efficient processes for the removal of toxic metals from water bodies has become a priority task for environmentalists. Biosorption processes are tangible alternatives to traditional methodologies, particularly if low metal concentration, large volume and cost are considered. The present communication reports the unexploited sorption properties of the Saraca indica leaf powder (SILP) for the removal of Cd(II) and Ni(II) from aqueous media. Sorption studies using standard practices were carried out in batch experiments as a function of biomass dosage, metal concentration, contact time, particle size and pH. Sorption studies result into the standardization of optimum conditions for the removal of Cd(II) - 92.60% and Ni(II) - 46.20% as follows: biomass dosage (4.0 g), metal concentration (Cd(II) 10 μg/cm3, Ni(ll) 10 μg/cm3) and volume of the test solution (200 cm') at pH 6.5 for Cd(II) and Ni(II). The present study explores for the first time, the efficacy of Saraca indica leaf powder as a novel and environment friendly possibility to remediate heavy metal contaminated water in a cost efficient manner.
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Authors and Affiliations

M.M. Srivastava
Aditya Chauhan
Pushpa Kumari
Parul Sharma
Shalini Srivastava
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Abstract

Pre-treatment techniques employed for exhaust emission control of compression ignition engines were found to reduce the emission levels by small percentage only, failing to meet the required emission regulations. Post-treatment technique including diesel particulate filtration, diesel oxidation catalysis and selective catalytic reduction is found to be an effective solution. While the fuel-based regeneration of diesel particulate filter leads to uncontrolled combustion affecting the durability of the filter. Development of an effective regeneration system is one of the major technical challenges faced by automotive industry for meeting emission norms. A composite regeneration system with the application of microwave energy is proposed in this paper. As an initial phase, a three-dimensional model of the system is developed and its flow analysis is carried out by considering the case of single channel flow. Simulation of the regeneration process is also done by developing a Simulink model. The results of simulation showed that an engine running continuously for a period of 24 hours would require three regenerations.
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Authors and Affiliations

Caneon Kurien
Ajay Kumar Srivastava
Joris Naudin
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Abstract

In the present study, treatment of synthetic wastewater containing phenol, resorcinol and catechol was studied in a sequencing batch reactor (SBR). Parameters such as hydraulic retention time (HRT) and filling time have been optimized to increase the phenol, resorcinol, catechol and chemical oxygen demand (COD) removal efficiencies. More than 99% phenol, 95% resorcinol and 96% catechol and 89% COD removal efficiency was obtained at optimum conditions of HRT = 1.25 d and fill time = 1.5 h. The heating value of the sludge was found to be 12 MJ/kg. The sludge can be combusted to recover its energy value.

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Authors and Affiliations

Chandrakant Thakur
Indra Deo Mall
Vimal Chandra Srivastava
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Abstract

A wideband antenna with dual band characteristic at 5.33/14.3GHz with resonating frequencies for wireless applications is presented. The strategy of the design is to introduce multiband in antenna band. Bandwidth of the antenna increases by embedding annular ring on the radiating patch and four bands are achieved by introducing coupling gap between the patches. Surface current distribution is analyzed at different resonating frequencies for understanding the radiation mechanism and effect of annular ring. The antenna parameters such as return loss, radiation pattern, gain, VSWR and group delay are discussed. The impedance bandwidth of the proposed dual band antenna at lower resonant frequency is 12.7% (simulated) and 9.8 % (measured) whereas at upper resonant frequency is 15.3 % (simulated) and 13.97 % (measured).

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Authors and Affiliations

Karunesh Srivastava
Sweta Singh
Aditya Kumar Singh
Rajeev Singh
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Abstract

In this paper, the problem of concentric pervious spheres carrying a fluid sink at their centre and rotating slowly with different uniform angular velocities Ω1. Ω2 about a diameter has been studied. The analysis reveals that only azimuthal component of velocity exists and the torque, rate of dissipated energy is found analytically in the present situation. The expression of torque on inner sphere rotating slowly with uniform angular velocity Ω1, while outer sphere also rotates slowly with uniform angular velocity Ω2, is evaluated. The special cases like, (i) inner sphere is fixed (i.e. Ω1 = 0), while outer sphere rotates with uniform angular velocity Ω2, (ii) outer sphere is fixed (i.e. Ω2 = 0), while inner sphere rotates with uniform angular velocity Ω1, (iii.) inner sphere rotates with uniform angular velocity Ω1, while outer rotates at infinity with angular velocity Ω2; have been deduced. The corresponding variation of torque with respect to sink parameter has been shown via figures. AMS subject classification – 76 D07.

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Authors and Affiliations

Deepak Kumar Srivastava
Raja Ram Yadav
Supriya Yadav
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Abstract

In the present work TiO2 nanoparticles (NPs) have been dispersed into three different nematic liquid crystals (2020, 1823A and 1550C) in different concentration. The value of the birefringence (Δn) has been calculated by the transmitted intensity method at a 632.8 nm wavelength. NLC 2020 used in the present study is a high birefringent material (Δn = 0.44), NLC 1550C is a low birefringent material (Δn = 0.067) and NLC 1823A is a mid birefringent material (Δn = 0.14). An increased value of birefringence has been found after dispersion of TiO2 NPs in all three NLCs but this increment depends upon the concentration of the dopant material, temperature range and chemical character of the mixtures. It is suggested that this LC materials can be applicable in making of phase shifters, compensators and many more photonic devices.

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Authors and Affiliations

G. Pathak
R. Katiyar
K. Agrahari
A. Srivastava
R. Dabrowski
K. Garbat
R. Manohar
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Abstract

In the present investigation optical, electro-optical and dielectric properties have been measured for nematic liquid crystal (NLC) material 1550C which consists of 4’-(trans, trans-4-alkylbicyclohexyl) carbonates and 4’-(4-(trans,trans-4-alkyl)-4-cyanobicyclohexane, dispersed with fluorescent dye (Benzo 2,1,3 Thiadiazole) in two different concentrations. Photoluminescence has been enhanced for a dye dispersed system which is the key finding of this investigation. UV absorbance study has also been performed and found to be increased for composite system. Enhanced birefringence after dispersion of dye into pure NLC is also a prominent result of this investigation. Relative permittivity, threshold voltage and dielectric anisotropy have also been measured and found to be increased. The outcome of the present work may be very useful in the construction of liquid crystal displays (LCDs).

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Authors and Affiliations

G. Pathak
K. Agrahari
A. Roy
A. Srivastava
O. Strzezysz
K. Garbat
R. Manohar
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Abstract

Barley phylloplane is seriously colonized by Drechslera graminea, the causal agent of leaf

stripe disease in the hos. The present study involved the elucidation of alterations induced

in the protein content of the host due to Drechslera infection. Naturally growing barley

plants were obtained from fields and Drechslera graminea was isolated and identified from

diseased plants’ leaves. After identification and preparation of the pure culture, the pathogen

was inoculated on plants grown under aseptic and controlled laboratory conditions.

Changes in the total soluble cytoplasmic proteins and defense enzymes of the host such

as polyphenol oxidase (PPO), peroxidase (POX), phenylalanine lyase (PAL) and tyrosine

ammonia lyase (TAL) were observed up to 5 h after inoculation. The results demonstrated

a significant effect of the pathogen on the cytoplasmic protein expression of the host as well

as in its defense system.

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Authors and Affiliations

Navodit Goel
Gaurav Jaiswal
Abhinav Kr Srivastava
Prabir Kumar Paul
Anukrati Goel

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