Faculty Publications
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Item Synthesis, characterization and studies on nonlinear optical parameters of 4-amino-5-(4-nitrophenyl)-1, 2, 4-triazole-3-thione(2010) Naseema, K.; Rao, V.; Manjunatha, K.B.; Umesh, G.; Sujith, K.V.; Kalluraya, B.In this paper, we report the synthesis, characterization and third order nonlinear optical properties of a new organic NLO material of 4-amino-5-(4-nitrophenyl)-1, 2, 4-triazole-3-thione (ANIT). The material was characterized by UV-vis and FTIR studies. The third order nonlinear optical properties have been investigated in dimethyl formamide (DMF) solution at 532 nm by using the Z-scan technique with pulses of nanoseconds duration. Open aperture data demonstrates the presence of two photon absorption at this wavelength. The nonlinear absorption coefficient ?, the nonlinear refractive index n2, the magnitude of effective third order susceptibility ?(3) and the second order hyperpolarizability ?h have been estimated as 2.99 cm/GW, -2. 53?×?10-11 esu, 2.72?×?10 -13esu and 0.281?×?10-31esu respectively. The values obtained are comparable with the values obtained for 4-methoxy chalcone derivatives and dibenzylideneacetone derivatives. The value of coupling factor have been estimated to be 0.17, indicating that the nonlinearity is electronic in origin. The compound exhibits good optical limiting at 532 nm with the limiting threshold of 80 ?J/pulse. The comparatively high value obtained indicates that this material may be used in optical device applications like optical limiters and optical switches. © 2010 Optical Society of India.Item Design and Synthesis of New Amides and Thioamides Derived from 3,4-Ethylenedioxythiophene as Potential Anticonvulsants(2010) Kulandasamy, R.; Vasudeva Adhikari, A.V.; Stables, J.P.Five new series of 3,4-ethylenedioxythiophene derivatives carrying important pharamacophores, viz., amide, ester, ether and active secondary aryl moieties have been designed and synthesized through multistep reactions starting from thiodiglycolic ester and diethyl oxalate. They have been characterized by elemental and spectral data. All the target compounds have been screened for their anticonvulsant activity at three different models viz. maximal electroshock (MES), subcutaneous metrazole (scMET), and 6 Hz screen and evaluated for their neurotoxicity in rotorod model. Compound 6a emerged as lead with no neurotoxicity. All the five series of compounds are safe in the toxicity studies at the maximum dose of 300 mg/kg of body weight. Amongst the tested compounds, the ester pharmacophore with thioamide fragment has showed better activity than the other analogs.Item New quinolin-4-yl-1,2,3-triazoles carrying amides, sulphonamides and amidopiperazines as potential antitubercular agents(2011) Thomas, K.D.; Vasudeva Adhikari, A.V.; Chowdhury, I.H.; Sumesh, E.; Pal, N.K.Three new series of quinoline-4-yl-1,2,3-triazoles carrying amides, sulphonamides and amidopiperazines were synthesized through multi-step reactions. The required intermediate, [1-(6-methoxy-2-methylquinolin-4-yl)-1H-1, 2,3-triazol-4-yl]methanol (2) was prepared by treating 4-azido-6-methoxy-2- methylquinoline (1) with propargyl alcohol. Three different series of compounds were synthesized from this intermediate. All the newly synthesized compounds were characterized by spectral and elemental analyses. The structure of 2 was confirmed by X-ray crystallographic study. Further, the title compounds were evaluated for their in vitro anti-bacterial activity against five different bacterial strains and antimycobacterial activity against Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis (ATCC 19420) and Mycobacterium fortuitum (ATCC 19542). Title compounds, 6a, 6d, 6i, 6j, 7e, 10a and 10i were found to be active against Mycobacterium tuberculosis H37Rv strain and could be lead molecules of interest. © 2011 Elsevier Masson SAS.Item Synthesis and characterization of temperature sensitive P-NIPAM macro/micro hydrogels(Elsevier B.V., 2011) JagadeeshBabu, P.E.; Suresh Kumar, R.; Maheswari, B.A thermo responsive macro porous poly(N-isopropylacrylamide) hydrogel was synthesized using free radical polymerization. The reaction was optimized by varying the reaction temperature, monomer, cross-linker and initiator based on the strength and swelling characteristics of the hydrogel. The morphology of the macro hydrogel was observed using scanning electron microscope (SEM). The swelling behavior of the macro hydrogel was performed gravimetrically and found that the gel synthesized at 36 °C had maximum deswelling ratio of 34.5 (-). These optimized values were further used to synthesis micro hydrogels using water-oil (w/o) emulsion technique. The morphology of the micro hydrogels were observed through SEM. Effect of water-oil ratio and stirrer speed on the mean particle size of the micro hydrogels were studied. Micro hydrogels synthesized at 1:1.5. w/o ratio and at 800. rpm had perfect spherical shape and had least particle mean diameter of 0.74 ?m, with SD of 0.5. Dye release kinetics with respect to temperature and time were studied using methylene blue solution. The release kinetic studies of micro hydrogel showed higher sustained release for 56. h compared to the macro hydrogel. © 2011 Elsevier B.V.Item Polysulfone/N-phthaloylchitosan novel composite membranes for salt rejection application(2011) Padaki, M.; Isloor, A.M.; Wanichapichart, P.N-phthaloylchitosan (CS) was synthesized by the reaction of chitosan with phthalic anhydride in dimethyl formamide. Different compositions of polysulfone (PSf) and N-phthaloylchitosan were used to prepare novel polysulfone/N-phthaloylchitosan (PSf/CS) composite membranes by phase inversion method. The composition ratios between the former and the latter were 80:20, 85:15, 90:10, and 95:5. Water flux results revealed that, PSf:CS 80:20 membrane is found to have greatest effective pore area while PSf:CS 95:05 membrane has the smallest value. The pore area is found to be larger with the increase in CS composition. In addition, its water swelling property increases with the increase of CS composition. Water flux results are in consistent with dielectric constant value. Use of known molecular weight of polyethylene glycol rejection study, revealed that, PSf:CS 95:05 membrane possessed the smallest pore size among these membranes. In conclusion, change of ratio between PSf and CS, considerably affects membrane pore size and hydrophilicity. For salt filtration, membrane PSf:CS 95:05 showed 93%, 76.11% and 70.12% rejection of MgSO4, Na2SO4, and NaCl, respectively. © 2011 Elsevier B.V.Item Influence of nanoscale NiO on magnetic and electrochemical behavior of PVDF-based polymer nanocomposites(2012) Bhatt, A.S.; Bhat, D.K.New poly(vinylidene fluoride) (PVDF)/NiO-based polymer nanocomposites were prepared by phase inversion method, using dimethyl formamide as solvent and deionized water as non-solvent. The structure and porous morphology of the membranes were studied by field emission scanning electron microscopy. The presence of NiO resulted in overall decrease in porosity and crystallinity of the nanocomposite membranes. Using electrochemical impedance spectroscopy, a maximum ionic conductivity of 1.08 × 10 -3 S cm -1 was obtained for PVDF membrane with 1 wt% content of NiO. The good efficiency of conductivity observed in the membrane was explained on the basis of decrease in crystallinity and movement of charge carriers in NiO structure. The magnetization of nanocomposite membranes gradually increased with increase in NiO content. © 2011 Springer-Verlag.Item Synthesis, characterization and desalination study of novel PSAB and mPSAB blend membranes with Polysulfone (PSf)(2012) Padaki, M.; Isloor, A.M.; A.F., A.F.; Abdullah, M.S.The present paper describes the synthesis of poly sulphonyl amino benzamide (PSAB) and methyalated poly sulphonyl amino benzamide (mPSAB) polymer, using terephthalic acid chloride and substituted 4-amino-1-benzensulphonmide in N-methyl-. 2-pyrrolidone. Polymers were characterized by FT-IR, NMR and GPC. Polysulfone composite membranes were prepared using these novel poymers by DIPS (Diffusion Induced Phase Seperation) method. These composite membranes are useful for water purification with special emphasis on sea water desalination. Newly prepared membranes were studied for salt rejection, water flux, molecular weight cut off by PEG solution, effect of the pH on water swelling and salt rejection and flux decline was also studied. 30 to 70% of the salt rejection was observed in all membranes. Effect of the dilution on salt rejection was studied using different concentration of NaCl solution varying from 1000. ppm to 3500. ppm. All the membranes showed 80% rejection for PEG having 1000. Da molecular weight. Contact angle and water swelling was measured to determine hydrophilicity of the membrane. Water swelling and salt rejection in different pH was also studied. © 2012 Elsevier B.V.Item Fabrication of styrene-acrylonitrile random copolymer nanofiber membranes from N,N-dimethyl formamide by electrospinning(SAGE Publications Ltd info@sagepub.co.uk, 2015) Senthil, T.; Anandhan, S.Ultrafine styrene-acrylonitrile random copolymer (SAN) nanofiber-based membranes were produced from N,N-dimethyl formamide solution by electrospinning. The purpose of this study was to find the optimum values of the electrospinning parameters and the influence of major significant parameters on the electrospun fiber morphology and the average fiber diameter (Davg) and its standard deviation using design of experiment. A backward elimination model for multiple regression analysis was employed to obtain quantitative interactions among selected electrospinning parameters and the final fiber diameter. The dependence of the Davg and morphology on the critical entanglement concentration was also studied. Morphology of the electrospun nanofiber mats were examined by scanning electron microscopy. Davg of electrospun SAN fibers increased considerably with increasing solution concentration. Fibers with diameters ranging from 40 to 650 nm were obtained. Analysis of variance was utilized to identify the statistically significant parameters (p < 0.05) and error variance. © The Author(s) 2013.Item Cocrystals of Ethenzamide: Study of Structural and Physicochemical Properties(American Chemical Society service@acs.org, 2016) Hariprasad, V.M.; Nechipadappu, S.K.; Trivedi, D.R.Pharmaceutical cocrystals of an analgesic drug ethenzamide (ETZ) with various coformers, namely, gallic acid (GA), 2-nitrobenzoic acid (2NB), 3-nitrobenzoic acid (3NB), 2,4-dinitrobenzoic acid (DNB), and 3-toluic acid (3TA) were synthesized by the solvent evaporation method. All the cocrystals were characterized by various analytical techniques, and the crystal structures were determined by the single-crystal X-ray diffraction method (SCXRD). SCXRD analysis revealed that all the synthesized cocrystals were formed through a robust supramolecular acid-amide heterosynthon except the ethenzamide/gallic acid cocrystal, where molecules interacted through O-H···O hydrogen bond involving -OH of gallic acid and oxygen of amide group of the ETZ molecule. The physicochemical properties such as stability, hygroscopicity, and solubility studies of the ETZ-GA cocrystal were evaluated. It was found that the ETZ-GA cocrystal has a higher solubility (2-fold) than that of the pure ETZ drug molecule. Hygroscopic study of the ETZ-GA cocrystal revealed that synthesized cocrystal was non-hygroscopic at ?75% RH conditions. The ETZ-GA cocrystal found to be stable for a time period of four months at ambient temperature. © 2016 American Chemical Society.Item T4-like Escherichia coli phages from the environment carry blaCTX-M(John Wiley and Sons Inc, 2018) Mohan Raj, J.R.; Vittal, R.; Huilgol, P.; Bhat, U.; Karunasagar, I.The resistance determinant blaCTX-M has many variants and has been the most commonly reported gene in clinical isolates of extended spectrum beta-lactamase producing Escherichia coli. Phages have been speculated as potential reservoirs of resistance genes and efficient vehicles for horizontal gene transfer. The objective of the study was to determine the prevalence and characterize bacteriophages that harbour the resistance determinant blaCTX-M. Escherichia coli specific bacteriophages were isolated from 15 samples including soil and water across Mangaluru, India using bacterial hosts that were sensitive to ?-lactams. Phenotypic and genotypic characterization based on plaque morphology, host range, restriction fragment length polymorphism (RFLP), presence of blaCTX-M and electron microscopy was performed. Of 36 phages isolated, seven were positive for Group 1 of blaCTX-M. Based on host range and RFLP pattern, the seven phages were classified into four distinct groups, each harbouring a variant of blaCTX-M. Five phages were T4-like Myoviridae by electron microscopy which was further confirmed by polymerase chain reaction (PCR) for T4 specific gp14. Generalized transduction of the CTX-M gene from these phages was also observed. The high prevalence (20%) of this gene blaCTX-M in the phage pool confirms the significant role of Myoviridae members, specifically T4-like phages in the dissemination of this resistance gene. Significance and Impact of the Study: The CTX-M gene that confers resistance to Beta-lactam class of drugs is widespread and diverse. Understanding mechanisms of antimicrobial resistance transfer is a key to devise methods for controlling it. Few studies indicate that bacteriophages are involved in the transfer of this gene but the type of phages involved and the degree of involvement remains to be explored. Our work has been able to identify the class of phages and the magnitude of involvement in the dissemination of this gene. © 2018 The Society for Applied Microbiology