NOPR Collection:

Electrochemical impedance spectroscopy of the poly-o-aminophenol film

2017-02-17T10:32:31Z

Title: Electrochemical impedance spectroscopy of the poly-o-aminophenol film Authors: Mahjani, M G; Gobal, F.; Jafarian, M Abstract: The technique of electrochemical impedance spectroscopy has been. employed to study the conductivity of poly-o-aminophenol film under different conditions and to 'test the validity of the transmission line model. In this regard, the effect of dc offset potential, film thickness, temperature and pH on the conductivity of the film has been studied. It is shown that reduced form of the polymeric film is more conductive than oxidized form. The semiconductivity is revealed to be p-type through the application of the Mott-Schottky equation. Page(s): 177-183

Fluorescence studies on mixed micelles of ionic-nonionic surfactants

2017-02-17T10:29:00Z

Title: Fluorescence studies on mixed micelles of ionic-nonionic surfactants Authors: Panda, A K; Chakraborty, A K Abstract: Fluorescence properties of ionic dyes using oppositely charged non-fluorescent dyes as quenchers in mixed surfactant of ionic-nonionic systems have been investigated. Cationic dye safranin O and anionic dye eosin Y are used as probes; bromocresol green, thymol blue and bromothymol blue are used as quenchers for safranin O, and crystal violet, toluidine blue and methylene blue are used as quenchers for eosin Y. The fluorescence characteristics in mixed micellar media of ionic and nonionic surfactants CTAB, CpC1, SDS, AOT, Triton X-100, Tween 20, and Brij 35 have been studied. The variations in the physico-chemical parameters. viz., cmc, aggregation number(n), binding constant between the quencher and the probe (K_SV), occupancy number of the quencher in the micelles (ń), the binding constant of the quencher with the micelle (K) in such interactions have been evaluated using suitable equations and the properties have been explained in terms of the micellar structures. Page(s): 184-189

Oxidative behaviours and relative reactivities of some aliphatic, heterocyclic and aromatic aldehydes towards bis(dihydrogentellurato )cuprate(III) and argentate(III) in alkaline medium

2017-02-17T10:25:17Z

Title: Oxidative behaviours and relative reactivities of some aliphatic, heterocyclic and aromatic aldehydes towards bis(dihydrogentellurato )cuprate(III) and argentate(III) in alkaline medium Authors: Gupta, Kalyan Kali Sen; Nandy, Bijay Kumar; Bera, Ashok Kumar; Gupta, Shipra Sen Abstract: The oxidative behaviours and relative reactivities of some aliphatic aldehydes, XCHO (where X = H - , Me - , MeCH₂ -, Me₂CH-), 2-furaldehyde and aromatic aldehydes, YC₆H₄CHO (where Y= -H, -NO₂, -Cl and -OMe) towards bis(dihydrogentellurato)metallate(III) ion (where M^IlI= CU^llI or Ag^III) in alkaline medium have been investigated. The reactions are first order each in [aldehyde] and [M^III(H²TeO⁶)²]^5- - but the rate is independent of [OH^-]. The values of k_obs in the oxidation of some aliphatic aldehydes, 2-furaldehyde and benzaldehyde in aqueous medium follow the order: Me₂CH - > MeCH₂ - > Me - > H - > C₄H₃O - > C₆H₅, -. The electron withdrawing substituents facilitate the rate of oxidation of benzaldehyde whereas electron donating substituents have opposite effect and the values of k_obs, follow the order: - NO₂ > - H > - Cl > - OMe. The pseudofirst order rate constants decrease considerably in benzaldehyde-d₁., than benzaldehyde under comparable condition of experiments. Irrespective of whether the substrate is aliphatic or aromatic, the oxidation reactions occur via free radical mechanism although the substituent and isotope effects in the oxidations of aromatic aldehydes indicate that C - H bond cleavage via proton transfer may also occur. The activation parameters of the reactions have been determined and the mechanism of the reactions is discussed. Page(s): 190-196

Nonequilibrium growth of Klebsiella ozaenae on agar plates

2017-02-17T10:14:06Z

Title: Nonequilibrium growth of Klebsiella ozaenae on agar plates Authors: Das, Ishwar; Kumar, Anuj; Singh, U K Abstract: Morphology and growth kinetics of the bacteria Klebsiella ozaenae on agar surface have been investigated. Bacterial colonies grow two dimensionally with random branches identical to nonequilibrium growth processes in non-living systems and generate self organization. The colony pattern is analysed and fractal dimensional is found to be 1.61 which is in excellent agreement with the expected value of the diffusion limited aggregation (DLA) model. Both phenotypic and genotypic adaptation are observed under different experimental conditions. Influence of certain vitamins, disinfectant, antibiotics and the microorganism Bacillus subtilis on the growth behaviour of K. ozaenae has been investigated. Page(s): 197-200