JCDAV College

Dasūa, India

JCDAV College

Dasūa, India

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Kumar R.,JCDAV College | Umar A.,Najran University | Kumar G.,JCDAV College | Nalwa H.S.,Advanced Technology Research
Ceramics International | Year: 2017

Waterborne diseases significantly affect the human health and are responsible for high mortality rates worldwide. Traditional methods of the treatment are now insignificant as maximum bacterial strains have developed multiple antibiotic resistance toward commonly used antibiotic drugs. Recently, ZnO nanostructures, due to their biocompatible nature, have attracted the attention of the scientific community to explore and to understand their cytotoxicity, interactions with biomolecules such as proteins, nucleic acids, fats, cell membranes, tissues, biological fluids, etc., and bio-safety for proper utilization in biomedical applications. Herein, we have reviewed the recent developments for the fabrication of ZnO nanomaterials with variable morphologies, factors influencing the growth, morphology and surface defects, and various laboratory methods to evaluate the antibacterial activities toward Gram-positive as well as Gram-negative bacterial strains. A comparative study is carried out to evaluate the mechanistic approach of ZnO nanomaterials toward Gram-positive as well as Gram-negative bacterial cells. ZnO nanomaterials can interact chemically as well as physically to exhibit antibacterial activities. Chemical interactions of the ZnO nanomaterials with bacterial cells lead to the photo-induced production of reactive oxygenated species (ROS), formation of H2O2, and release of Zn2+ ions. In contrast, the physical interaction can show biocidal effects through cell envelope rupturing, cellular internalization or mechanical damage. Finally, surface activation through amine functionalization of ZnO nanoparticles for better antibacterial effects and cytotoxicity of ZnO nanoparticles toward cancer cells is also reviewed. © 2016 Elsevier Ltd and Techna Group S.r.l.


Kumar G.,JCDAV College | Kumar R.,JCDAV College | Hwang S.W.,Najran University | Umar A.,Najran University
Journal of Nanoscience and Nanotechnology | Year: 2014

This work reports a facile and large-scale synthesis of ZnO nanoparticles by simple self-propagating solution combustion method using dextrose as fuel and their effective use as a photocatalyst for photocatalytic degradation of Direct Red-23 (DR-23) dye in an immersion well type photo-reactor. The prepared ZnO nanoparticles were characterized by various analytical tools using field emission scanning electron microscopy (FESEM) attached with energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) pattern, Fourier transform infrared (FTIR) spectroscopy and UV-Vis. spectroscopy measurements. The detailed characterizations confirmed that the prepared ZnO nanoparticles are pure, well-crystalline and possessing wurtzite hexagonal phase. Almost complete photo-degradation of the DR-23 was observed in 110 min. under UV irradiation in presence of ZnO nanoparticle photocatalyst. This study reveals that simply prepared ZnO nanomaterials are effective photocatalyst for the photocatalytic degradation of various toxic chemicals and pollutants. Copyright © 2014 American Scientific Publishers All rights reserved.


Kumar R.,JCDAV College | Kumar G.,JCDAV College | Umar A.,Najran University
Journal of Nanoscience and Nanotechnology | Year: 2014

This review summarizes the work principles of pulse laser deposition (PLD) apparatus, physical processes like ablation, and plasma plume formation accompanying the deposition of un-doped ZnO from target to substrate material. Various modes of deposition and factors influencing the properties of thin films such as substrate temperature, background gas pressure, laser energy density (laser fluence), target to substrate distance, repetition rate, oxygen partial pressure in deposition chamber, deposition time and post growth annealing which control deposition parameters such as adsorption, desorption, surface diffusion, nucleation, and crystallization/re-crystallization are also discussed in this review. Moreover, various film properties such as morphology, roughness of the film surface, film thickness, grain size, optical transmittance, sensitivity, electrical conductivity, uniformity and electrical resistivity of the deposited ZnO thin films have also been enumerated in the present review. © 2014 American Scientific Publishers All rights reserved.


Kumar R.,JCDAV College | Al-Dossary O.,King Saud University | Kumar G.,JCDAV College | Umar A.,Najran University
Nano-Micro Letters | Year: 2014

Because of the interesting and multifunctional properties, recently, ZnO nanostructures are considered as excellent material for fabrication of highly sensitive and selective gas sensors. Thus, ZnO nanomaterials are widely used to fabricate efficient gas sensors for the detection of various hazardous and toxic gases. The presented review article is focusing on the recent developments of NO2 gas sensors based on ZnO nanomaterials. The review presents the general introduction of some metal oxide nanomaterials for gas sensing application and finally focusing on the structure of ZnO and its gas sensing mechanisms. Basic gas sensing characteristics such as gas response, response time, recovery time, selectivity, detection limit, stability and recyclability, etc are also discussed in this article. Further, the utilization of various ZnO nanomaterials such as nanorods, nanowires, nano-micro flowers, quantum dots, thin films and nanosheets, etc for the fabrication of NO2 gas sensors are also presented. Moreover, various factors such as NO2 concentrations, annealing temperature, ZnO morphologies and particle sizes, relative humidity, operating temperatures which are affecting the NO2 gas sensing properties are discussed in this review. Finally, the review article is concluded and future directions are presented. © 2014, SpringerOpen. All Rights Reserved.


Kumar R.,JCDAV College | Kumar G.,JCDAV College | Al-Dossary O.,King Saud University | Umar A.,Najran University
Materials Express | Year: 2015

The present review focuses on the growth, properties and applications of ZnO thin films grown by various physical deposition techniques. An overview on several deposition methods such as thermal evaporation, arc deposition, pulse laser deposition and sputtering for the growth of ZnO thin films are discussed in this review. Several factors such as substrate temperature, gas pressures, oxygen partial pressures, and post growth annealing temperatures which influence the properties of ZnO thin films are also discussed. Various ZnO thin film properties such as surface morphologies, surface film thickness, grain size, optical transmittance, sensitivity, electrical conductivity, uniformity and electrical resistivity are presented in this review. In addition, numerous applications of ZnO thin films, for instance, thin film based gas sensors, surface acoustic wave (SAW) devices; thin film transistors (TFTs), light emitting diodes (LEDs) and solar cells are discussed. © 2015 by American Scientific Publishers. All rights reserved.


Kumar R.,JCDAV College | Kumar G.,JCDAV College | Akhtar M.S.,Chonbuk National University | Umar A.,Najran University
Journal of Alloys and Compounds | Year: 2015

A simple, facile and rapid solution combustion method utilizing dextrose as fuel was employed to synthesize zinc oxide (ZnO) nano-aggregates at high temperature 450 °C. The synthesized nanomaterials were characterized in terms of their morphological, structural, compositional, optical and photocatalytic properties. The detailed characterizations confirmed that the synthesized ZnO nano-aggregate possessed high density and exhibit well-crystallinity with good optical properties. The sonophotocatalytic properties of the synthesized ZnO nano-aggregates was carried out by performing the degradation of methyl orange (MO) dye under UV light. A strong synergism was observed between UV light and ZnO nano-aggregates for the photodegradation process, whereas sonolytic and photolytic degradation processes were found to operate independently. The presence of air in the aqueous suspensions of MO dye was also shown a significant impact in the photodegradation rate. © 2015 Elsevier B.V. All rights reserved.


Kumar R.,JCDAV College | Kumar G.,JCDAV College | Umar A.,Najran University
Materials Letters | Year: 2013

In this paper, we report the successful synthesis of ZnO nano-mushrooms (ZNM) by the solution combustion method and their effective use as a photocatalyst for photocatalytic degradation of methyl orange. The synthesized ZNM were characterized in terms of their morphological, structural and optical properties. The detailed characterizations confirmed that the synthesized ZNM possess mushroom-shaped morphologies, grown in high density and exhibit well-crystallinity with good optical properties. The photocatalytic properties of ZNM were investigated under UV light irradiation via methyl orange (MO) as a model organic compound. The influence of operating parameters such as amount of ZNM and dye concentration was thoroughly examined in order to obtain best condition for photocatalytic degradation. Under optimum condition, over 92% photo-degradation of MO was achieved in 210 min. © 2013 Elsevier B.V.


Chauhan S.,H P University | Sharma K.,H P University | Rana D.S.,H P University | Kumar G.,JCDAV College | Umar A.,Najran University
Journal of Solution Chemistry | Year: 2013

Apparent molar volumes (φ v ), apparent molar adiabatic compressions (φ κ) and thermodynamic parameters of cetyltrimethyl ammonium bromide (CTAB) in 0.001, 0.01, 0.05 and 0.1 mol·dm-3 aqueous solution of glycine in the temperature range 25-40 C (at an interval of 5 C) have been determined from density, speed of sound and conductometric measurements, respectively. The above calculated parameters were found to be sensitive to the interactions prevailing in the glycine-CTAB-water system. The analysis of the data was found to suggest that the φ v and φ κ values decrease sharply in the pre-micellar region and thereafter the decrease is almost linear at all concentrations of glycine, showing the dominance of hydrophobic interactions and facilitating the process of micellization. The φ v and φ κ values of these surfactants are found to be completely consistent with temperature over the entire concentration range. From conductance studies, the value of critical micelle concentration has been calculated, which shows dependence on the concentration of glycine as well as on temperature. A reasonably good qualitative correlation is found to exist with regard to CTAB-glycine interactions obtained from the conductance measurements and those from density and sound velocity measurements. All these observations demonstrate that this amino acid-surfactant system behaves in a different manner as compared to amino acid-electrolyte systems. © 2013 Springer Science+Business Media New York.


Chauhan S.,H P University | Sharma K.,H P University | Rana D.S.,H P University | Kumar G.,JCDAV College | Umar A.,Najran University
Journal of Molecular Liquids | Year: 2012

In the present studies, micellization behavior of cetyltrimethylammonium bromide, CTAB (cationic surfactant) has been studied in the aqueous solution, containing 0.001, 0.005, 0.01, 0.025, 0.05, 0.075 and 0.1 M leucine as a solvent, using specific conductances (κ), densities (d) and velocities of sound (v), in the temperature range 25-40 °C at an interval of 5 °C. The cmc of CTAB was determined from the plots of specific conductance (κ) of CTAB in aqueous leucine solution. The cmc values of surfactant increase with increase in temperature but they decrease linearly with increase in the concentration of the leucine. By using cmc data various thermodynamic parameters have also been evaluated. The apparent molar volume (φ v) and apparent molar adiabatic compressibility (φ κ) have been computed using densities and velocities of sound data. The above calculated parameters were found to be sensitive towards the interactions prevailing in the leucine-CTAB-water systems. The analysis of the data is found to suggest that φ v and φ κ values in general are positive at all temperatures and increase with rise in temperature while decrease sharply to about 0.8 mM [CTAB] at all concentrations of leucine. Thereafter, the decrease is almost linear. The cmc as determined from the fluorescence measurements indicating a transition point of I 1/I 3 plot which shows that the cmc lies at ≈ 0.8 mM, the results of which are consistent with the other physico-chemical studies. A reasonably good qualitative correlation is found to exist with regard to CTAB-leucine interactions obtained from the different measurements. © 2012 Elsevier B.V. All rights reserved.


Chauhan S.,H P University | Sharma K.,H P University | Kumar K.,H P University | Kumar G.,JCDAV College
Journal of Surfactants and Detergents | Year: 2014

Densities (d) and sound velocities (v) of an ethoxylated alkyl phenol surfactant in aqueous solutions of two amino acids, namely glycine and leucine, have been measured over a temperature range of 25-40 °C at intervals of 5 °C by using density and sound analyzers. Experimental data have been used to calculate the isentropic compressibilities (ks), apparent molar volumes (φν) and apparent molar adiabatic compressions (φκ) in order to explain amino acid-surfactant interactions. The results have been discussed in terms of the effect of amino acids on the micellization behavior of the surfactant. A comparative study of both the amino acids has been carried out and is found that both amino acids produce a decrease in the CMC value of nonionic surfactant but to different extents. © AOCS 2013.

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