Maharaja Krishnakumarsinhji Bhavnagar University

www.mkbhavuni.edu.in
Bhavnagar, India

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Desai N.C.,Maharaja Krishnakumarsinhji Bhavnagar University | Rajpara K.M.,Maharaja Krishnakumarsinhji Bhavnagar University | Joshi V.V.,Maharaja Krishnakumarsinhji Bhavnagar University
Journal of Fluorine Chemistry | Year: 2013

New 5-arylidene derivatives, which bear a fluorine atom in the 4th position of the benzoyl group as starting compound, have been synthesized by the condensation of 4-fluoro-N-(4-methyl-5-(2-(4-oxo-3-phenylthiazolidin-2-ylidene) hydrazinecarbonyl)thiazol-2-yl)benzamide and Knoevenagel condensation with aromatic aldehydes to form N-(5-(2-(5-(arylidene)-4-oxo-3-phenylthiazolidin-2- ylidene)hydrazinecarbonyl)-4-methylthiazol-2-yl)-4-fluorobenzamides (6a-o) through conventional and microwave methods. The structures of synthesized compounds were established by spectroscopic as well as spectrometric techniques (IR, 1H NMR, 13C NMR, 19F NMR spectroscopy and mass spectrometry). Antimicrobial screening of 5-arylidene derivatives 6a-o was done against Gram-positive bacteria (Staphylococcus aureus and Streptococcus pyogenes), Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and fungi (Candida albicans, Aspergillus niger, and Aspergillus clavatus) using serial broth dilution method. Compounds 6g and 6j were found to be most active at MIC 12.5 μg/mL against selected bacterial strains and compound 6e was found to be most active at MIC 25 μg/mL against selected fungal strains. It has been further observed that the presence of fluorine atom at the 4th position of the benzoyl group in the final compounds is essential for enhancing the antimicrobial activity. © 2012 Elsevier B.V.


Vala A.K.,Maharaja Krishnakumarsinhji Bhavnagar University
Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry | Year: 2014

Gold nanoparticles (GNPs) production by the green chemistry approach was examined using a marine-derived fungus Rhizopus oryzae. The test fungi revealed production of gold nanoparticles both, extra and intracellularly. Extracellular biosynthesis was found at the gold chloride concentration 0.25 mM, as evidenced by lavender-purple color of the solution. At other concentrations, intense coloration in biomass was observed indicating intracellular biosynthesis of gold nanoparticles. To the best of the author's knowledge, this is first ever report on extracellular biosynthesis of GNPs by R. oryzae under static condition. Copyright © Taylor & Francis Group, LLC.


Vala A.K.,Maharaja Krishnakumarsinhji Bhavnagar University
Environmental Progress and Sustainable Energy | Year: 2015

Production of gold nanoparticles (GNPs) by biological route was examined using a marine-derived fungal isolate. The isolated strain was identified as Aspergillus sydowii based on morphological traits and molecular identification technique. The test strain exhibited the potential to produce GNPs. A noteworthy observation was that mode of biosynthesis (extracellular/intracellular) depended on supplied gold ion concentration. As revealed by the color of the filtrate, at lower concentrations of gold ion larger size particles were obtained, while higher concentrations supported synthesis of smaller particles. The particles biosynthesized at 3 mM gold chloride were found to be spherical and nearly monodisperse in nature. The particles were found to be in the size range of 8.7-15.6 nm with a mean diameter of 10 nm. Based on the findings it can be concluded that marine-derived fungus A. sydowii could be a promising candidate for synthesizing GNPs using green chemistry approach. Hence, the protocol is ecofriendly. The present study is the first ever report on biosynthesis of GNPs using a marine-derived A. sydowii. © 2014 American Institute of Chemical Engineers.


Gupta S.K.,Maharaja Krishnakumarsinhji Bhavnagar University | Soni H.R.,Maharaja Krishnakumarsinhji Bhavnagar University | Jha P.K.,Maharaja Krishnakumarsinhji Bhavnagar University
AIP Advances | Year: 2013

In the frame work of density functional theoretical calculations, the electronic and lattice dynamical properties of graphene (multilayers and supercell) have been systematically investigated and analyzed using the plane wave pseudopotentials within the generalized gradient approximation and local density approximation functional. We have also studied the functionalization of graphene by adsorption and absorption of transition metals like Al and Ag. We find that the electronic properties exhibit large sensitivity to the number of layers and doping. The Al and Ag doped graphene exhibits peak at Fermi level in the density of states arising from the flat bands near Fermi level. The bonding of metal atoms and graphene leads to a charge transfer between them and consequently shift Fermi level with respect to the conical point at K-point. The adsorption of AgAl atoms suggests an effective interaction between the adatoms and graphene layers without disturbing the original graphene structure of lower graphene layers. Compared to single layer graphene, the optical phonon E 2g mode and out of plane ZA mode at Γ-point splits in the bi-, tri- and four- layer graphene. We observe a shift for highest optical branch at Dirac K- point. We find that the different derivatives of graphene have different phonon dispersion relations. We demonstrate that there is removal of degeneracy of ZOZA modes at K- point with transition metal doping. The highest optical phonon branch becomes flat at Dirac point with doping of transition metals. Our study points that the substituted graphene sheets can have potential applications in ordered-disordered separated quantum films with two to four layers of atoms and new nano devices using graphene. © 2013 Copyright 2013 Author(s). This article is distributed under a Creative Commons Attribution 3.0 Unported License.


Desai N.C.,Maharaja Krishnakumarsinhji Bhavnagar University | Rajpara K.M.,Maharaja Krishnakumarsinhji Bhavnagar University | Joshi V.V.,Maharaja Krishnakumarsinhji Bhavnagar University
Bioorganic and Medicinal Chemistry Letters | Year: 2012

The synthesis of a novel series of 2-(5-(2-chloro-6-fluoroquinolin-3-yl)-3- (aryl)-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-ones (4a-l) and N-(4-(2-chloro-6-fluoroquinolin-3-yl)-6-(aryl)pyrimidin-2-yl) -2-morpholinoacetamides (7a-l) are described in the present paper. The chemical structures of compounds have been elucidated by IR, 1H NMR, 13C NMR and mass spectral data. Antimicrobial activity was measured against Escherichia coli (MTCC 443), Pseudomonas aeruginosa (MTCC 1688), Staphylococcus aureus (MTCC 96), Streptococcus pyogenes (MTCC 442), Candida albicans (MTCC 227), Aspergillus niger (MTCC 282) and Aspergillus clavatus (MTCC 1323) by serial broth dilution. Evaluation of antimicrobial activity showed that several compounds exhibited greater activity than reference drugs and thus could be promising new lead molecules. © 2012 Elsevier Ltd. All rights reserved.


Desai N.C.,Maharaja Krishnakumarsinhji Bhavnagar University | Bhatt N.,Maharaja Krishnakumarsinhji Bhavnagar University | Somani H.,Maharaja Krishnakumarsinhji Bhavnagar University | Trivedi A.,Maharaja Krishnakumarsinhji Bhavnagar University
European Journal of Medicinal Chemistry | Year: 2013

A series of thiazole clubbed 1,3,4-oxadiazole derivatives (5a-l) have been synthesized and characterized by IR, 1H NMR, 13C NMR and mass spectral analysis. Synthesized compounds were evaluated for their antimicrobial and cytotoxic activities. The results indicated that, compounds 5c and 5i exhibited the most potent antibacterial activity. Compound 5f was found to be the most potent antifungal agent. The structure activity relationship revealed that the presence of electron withdrawing groups at para position of phenyl ring remarkably enhanced the antibacterial activity of synthesized compounds. Further, the results of preliminary MTT cytotoxicity studies on HeLa cells suggested that potent antimicrobial activity of 5b, 5c, 5f, 5h and 5i is accompanied by low cytotoxicity. © 2013 Elsevier Masson SAS. All rights reserved.


Desai N.C.,Maharaja Krishnakumarsinhji Bhavnagar University | Rajpara K.M.,Maharaja Krishnakumarsinhji Bhavnagar University | Joshi V.V.,Maharaja Krishnakumarsinhji Bhavnagar University
Bioorganic and Medicinal Chemistry Letters | Year: 2013

A series of novel compounds 6-amino-1-((1,3-diphenyl-1H-pyrazole-4-yl) methyleneamino)-4-(aryl)-2-oxo-1,2-dihydropyridine-3,5-dicarbonitriles (4a-t) were synthesized and characterized by IR, 1H NMR, 13C NMR and mass spectral data. These compounds were screened for their in vitro antibacterial activity against Staphylococcus aureus, Streptococcus pyogenes (Gram positive), Escherichia coli, Pseudomonas aeruginosa (Gram negative) by serial broth dilution and cytotoxic activity (NIH 3T3 & HeLa) by MTT assay. The results indicated that compounds 4g, 4i, 4m, 4o, 4r and 4t exhibit potent antibacterial activity against bacterial strains at non-cytotoxic concentrations. © 2013 Elsevier Ltd. All rights reserved.


Vala A.K.,Maharaja Krishnakumarsinhji Bhavnagar University
BioTechnology: An Indian Journal | Year: 2014

The objective of the work was to explore potential of marine-derived fungi for biosynthesis of gold nanoparticles (GNPs). Three marine-derived fungal isolates viz. Aspergillus candidus, Aspergillus flavus and Aspergillus niger have been examined for their ability to biosynthesize GNPs.All the test isolates were challenged with different concentrations (0.25, 0.5, 1, 2 and 3mM) of gold (III) chloride under static condition at 27°C for 72h. The isolates could biosynthesize spherical GNPs mostly extracellularly. In certain cases,mode of synthesis extra/intracellular was observed to be dependent on gold ion concentrations. While there is no much information available on exploitation of marine-derived fungi for biosynthesis of metal nanoparticles, present findings suggest marinederived fungi as potential resource for developing cost-effective green technology for GNP synthesis. © 2014 Trade Science Inc. - INDIA.


Gupta S.K.,Maharaja Krishnakumarsinhji Bhavnagar University | Gupta S.K.,Michigan Technological University | Jha P.K.,Maharaja Krishnakumarsinhji Bhavnagar University
International Journal of Hydrogen Energy | Year: 2013

We report first-principles pseudopotential method and density functional linear response theory calculations of the structural, electronic, vibrational and thermodynamical properties of LaH2 in fluoride phase at zero and high pressures. The electronic band structure and first time calculated pressure dependent lattice dynamic properties show that the LaH2 is metallic in nature at zero pressure. The pressure dependent electronic band structure calculations show that the bands are closing and reopening with pressure. The phonon mode softens at 11 GPa indicating an instability in lattice structure and pressure induced transverse acoustic phonon mode driven displacive type structural phase transition. The LaH2 also shows weak superconductivity at zero pressure. The valence charge electron density at 46 GPa shows a cage type charge contour and a space where hydrogen can be absorbed and filled easily. There is a considerable charge accumulation in the bonding region of La and H atoms, which strengthens covalent character of LaH 2, and henceforth this material can be one of the best materials for hydrogen storage application at high pressures. © 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.


Soni H.R.,Maharaja Krishnakumarsinhji Bhavnagar University | Jha P.K.,M. S. University of Baroda
Solid State Communications | Year: 2014

The present paper reports the calculated vibrational and elastic properties of some two dimensional carbon allotropes such as graphene, α-, β- and γ-graphynes using first principles density functional theory. The phonon modes of graphynes show quite distinct behavior than graphene and have real frequency throughout the Brillouin zone thus indicating dynamically stable structures. The out of plane, ZA mode is more dispersive in the case of graphynes. We have discussed the implications of phonon modes to the thermal conductance in graphynes and graphene. We have also calculated the elastic constants for graphene and graphynes. Calculated elastic constants of graphynes show more anisotropic conformer nature than graphene. © 2014 Elsevier Ltd.

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