Showing papers by "University of Madras published in 1989"
TL;DR: In this article, the authors used methylviologen as an electron relay for the transfer of conduction band electron of the semiconductor to the hydrogen ion present in the aqueous solution.
56 citations
TL;DR: Renforcement de diverses formulations de caoutchouc par des fibres de noix de coco, vulcanisation and proprietes mecaniques des vulcanisats as mentioned in this paper.
Abstract: Renforcement de diverses formulations de caoutchouc par des fibres de noix de coco, vulcanisation et proprietes mecaniques des vulcanisats
56 citations
TL;DR: Strains of fluorescent and nonfluorescent bacteria that were isolated from rice rhizospheres of Southern India and showed antagonism towards Rhizoctonia solani were evaluated for biological control of rice sheath-blight and inhibited mycelial growth of R. solani.
Abstract: Strains of fluorescent and nonfluorescent bacteria that were isolated from rice rhizospheres of Southern India and showed antagonism towardsRhizoctonia solani were evaluated for biological control of rice sheath-blight (ShB). Efficient strains of bacteria inhibited mycelial growth ofR. solani, affected sclerotial viabilityin vitro and protected IR 20 and TKM 9 rice seedlings from infection byR. solani in greenhouse tests. Pretreatment of sclerotia in bacterial suspensions resulted in reductions in ShB lesion sizes up to 31 to 44% in IR20 and 58 to 74% in TKM 9 rice. In field plots, IR 50 and TKM 9 rice plants raised from bacterized seeds had 65 to 72% less ShB than those plants from untreated seeds.
53 citations
TL;DR: In the absence of any sacrificial agent as mentioned in this paper, hydrogen production with visible light using Pt, Pd and Rh loaded-WO3 particles suspended in aqueous methyl viologen solution has been achieved with high efficiency.
44 citations
TL;DR: Nanophase oxides (Al2O3, MgO, ZnO and TiO2), with typical grain sizes in the range 2-20 nm, have been synthesized by the condensation of ultrafine particles in a convective inert gas followed by their collection and in-situ consolidation in vacuum at ambient temperature as discussed by the authors.
Abstract: Nanophase oxides (Al2O3, MgO, ZnO and TiO2), with typical grain sizes in the range 2–20 nm, have been synthesized by the condensation of ultrafine particles in a convective inert gas followed by their collection and in-situ consolidation in vacuum at ambient temperature. These new materials, owing to the reduced scale of their grains along with the enhanced cleanliness of their grain boundaries, are found to have significantly improved properties relative to those of their coarser-grained, conventionally-prepared counterparts. Nanophase rutile (TiO2) with an initial mean grain diameter of 12 nm, for example, has been found to sinter at 400 to 600°C lower temperatures than conventional rutile powders, without the need for compacting or sintering aids, while retaining a small grain size. Additionally, the importance of the extremely clean surfaces obtained with the gas condensation method has been demonstrated by comparing the sintering behavior of powders with and without air exposure prior to consolidation. The research completed on the processing and properties of nanophase ceramics is reviewed, and the potential for engineering advanced ceramics using the nanophase processing method is discussed.
34 citations
TL;DR: In this article, the structural changes effected during sintering were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) experiments.
Abstract: WO3 semiconductor particles, useful in solar energy conversion processes, were doped with transition metal ions, Ti(III), V(IV), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Ru(III) by a high-temperature sintering technique. The method of preparation of these photocatalysts is described in detail. The structural changes effected during sintering were investigated by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The XRD analysis indicated that the monoclinic crystal structure of WO3 was not altered during sintering. SEM studies showed that the sizes of the particles ranged from 1 to 10 μm and the crystallinity was increased due to doping. The dopants were found to be mostly distributed on the surface of WO3 particles.
25 citations
TL;DR: In this paper, the authors investigated the kinetics of formation of the radical cation, ABTS.+ at 417 nm and showed that the rate of formation was second-order, first-order each in [ABTS] and [peroxide], except for H2O2 which reacted through Michaelis-Menten kinetics.
Abstract: The kinetics of oxidation of 2,2′-azinobis-(3-ethylbenzothiazole-6-sulphonate) (ABTS) by the inorganic peroxides, peroxomonosulphate, peroxodisulphate, peroxodiphosphate, and hydrogen peroxide were investigated in aqueous solution. The kinetics of formation of the radical cation, ABTS.+, on one-electron abstraction by these peroxides and the further reaction of ABTS.+ with higher concentrations of these peroxides at longer time scale were studied by following the growth and decay of the radical cation, ABTS.+ at 417 nm. The rate of formation of ABTS.+ was found to obey a total second-order, first-order each in [ABTS] and [peroxide], except for H2O2, which reacted through Michaelis-Menten kinetics. All the peroxides investigated were found to react with ABTS.+; however peroxodisulphate alone oxidized ABTS.+ to the dication (ABTS++), the other peroxides reacted via ionic mechanism, probably forming sulphoxide and sulphone as products. The kinetics of decay of the radical cation, ABTS.+, was also found to follow a total second-order, first-order each in [ABTS.+] and [peroxide], except peroxodiphosphate the reaction of which obeyed Michaelis-Menten kinetics. The effect of pH and temperature were also investigated in all the systems and the kinetic and thermodynamic parameters were evaluated and discussed with suitable reaction mechanisms.
25 citations
TL;DR: In this article, the effect of crosslinking by polyfunctional alcohols such as castor oil, trimethylolpropane, and poly(vinyl alcohol) on mechanical properties is compared in case of hydroxyterminated polybutadiene based polyurethane systems.
Abstract: Polyurethane elastomers were prepared from structurally distinct hydroxyterminated polybutadiene and polyether-ester based prepolymers with diisocyanates such as hexamethyl-enediisocyanate, toluenediisocyanate, and diphenylmethanediisocyanate by the one short polymerization process The effect of crosslinking by polyfunctional alcohols such as castor oil, trimethylolpropane, and poly(vinyl alcohol) on mechanical properties is compared in case of hydroxyterminated polybutadiene based polyurethane systems The effect of crosslinking by trimethylolpropane on the mechanical properties was quantitatively studied in all the prepolymers based polyurethane systems Crosslinking was also induced in the polyurethanes by taking higher NCO/OH ratio (R value) and the observations on mechanical properties are compared with those prepared with trimethylolpropane crosslinking The thermal degradation of the polymers was studied in an oxygen atmosphere and interpreted with respect to their structure
23 citations
TL;DR: Phenol oxidase of Fasciola gigantica exists both as the soluble form as well as the membrane-bound form, which is considered to be a tyrosinase type because it is capable of oxidizing mono- and diphenol and is inefficient in oxidizing paraphenols.
Abstract: Phenol oxidase of Fasciola gigantica exists both as the soluble form as well as the membrane-bound form. The membrane-bound enzyme is considered to be a tyrosinase type because it is capable of oxidizing mono- and diphenol and is inefficient in oxidizing paraphenols. The soluble enzyme is a laccase type showing more affinity to various diphenols and paraphenols. Membrane-bound enzyme exists as isoenzymes, showing 3 fractions, of which the slow-moving fraction is capable of oxidizing both 4-methyl catechol and catechol, whereas the two remaining fractions are specific to 4-methyl catechol only. Soluble enzyme exists as a single homogeneous form showing affinity to both mono- and diphenols. Inhibition of the enzyme by potassium iodide and mercuric chloride indicates the active tyrosyl and SH groups of the enzyme. Inhibition of the enzyme by sodium diethyl dithiocarbamate and phenyl thiourea indicates that copper is the prosthetic group of the enzyme.
19 citations
TL;DR: The photocatalytic efficiencies of these doped samples were investigated by carrying out the decomposition of peroxomonosulphate (PMS, HSO5−) over the doped and undoped WO3 particles as discussed by the authors.
Abstract: WO3 particles were doped with the transition metal ions TiIII, VIV, CrIII, MnII, FeIII, CoII, NiII, CuII, ZnII, RuIII and V2O5 to increase the visible light absorption. The photocatalytic efficiencies of these doped samples were investigated by carrying out the decomposition of peroxomonosulphate (PMS, HSO5−) over the doped and undoped WO3 particles. PMS is capable of reacting with both the photogenerated holes and electrons. The effect of initial concentrations of PMS, amount of catalyst, pH, dopants and percentage doping on the photocatalytic efficiency of WO3 are investigated and are discussed.
19 citations
TL;DR: In this article, the suitability of a new coenzyme B12 model built upon the quadridentate tetraza equatorial chelate, 3,8-dimethyl-5,6-benzo-4,7-diazadeca-3, 7-diene-2,9-dione dioxime [(DOH)2bzo] as a non-biological mimic of coenase B12 and to establish a quantitative electrochemical comparison with the Costa-type models.
TL;DR: These results, as well as the cluster analysis, indicate the relative abundance of Biovar III isolates of P. fluorescens in south Indian soils and rice rhizosphere.
TL;DR: In this paper, the ammonium salt of dodecyl dithiocarbamic acid as an anionic collector was used as a chelating surfactant for column flotation.
Abstract: The concentration of Cu, Ni, Zn, and Cd ions by electroflotation using the ammonium salt of dodecyl dithiocarbamic acid as an anionic collector is examined. Quantitative studies reveal better separation efficiency by this method as compared to column flotation using dodecyl dithiocarbamic acid ligand as a chelating surfactant.
TL;DR: Lactate dehydrogenase of Setaria digitata exhibited an optimum pH of 7.0-8.0 and showed resistance to high temperature and the inhibition/activation of various anions differed in both the forward and backward directions.
TL;DR: B. vellavoli was overdispersed in both host species populations, and the expected distribution on the basis of the negative binomial was found to be very close to the observed distribution on 70–160 and 270–350 mm size classes of P. chinensis and P. argenteus.
TL;DR: In this paper, maleic and citraconic anhydrides were reacted with several diamines to obtain a novel class of high temperature resistant bisimides, which were characterized by melting points, elemental analysis, UV-Vis, 1H- and 13C-NMR, and mass spectral analysis.
Abstract: Maleic and citraconic anhydrides were reacted with several diamines to obtain a novel class of high temperature resistant bisimides.1–3 The bisimides were characterized by melting points, elemental analysis, UV–Vis, 1H- and 13C-NMR, and mass spectral analysis. The bisimide monomers were then polymerized by the addition process. A poly(amidemaleimide) was also synthesized by reacting maleic anhydride with p-aminobenzhydrazide. The thermal stability of these highly crosslinked poly(bisimide)s were examined by TGA and DTA. A neat bisimide monomer obtained from 2,2′-bis[4(p-aminophenoxy)phenyl] propane with maleic anhydride namely, 2,2′-bis[4-(p-maleimidophenoxy)phenyl]propane was reacted with 2,2′-bis[4(p-aminophenoxy)phenyl]propane by the Michael reaction.4 A fiber glass cloth reinforced laminate was prepared from bismaleimide and amine mixture and the mechanical properties of the test laminate evaluated.
TL;DR: In this paper, the three possible mono methyl substituted m -dinitrobenzenes were compared with m-dinitronzene as cathode materials in magnesium batteries, and the compounds with ortho or para substituted groups showed better ampere hour efficiencies than those with meta substituted groups.
TL;DR: In vivo binding of exogenous Cu to different haemolymph fractions was quantitatively determined in specimens of the estuarine crab Scylla serrata injected with Cu as cupric chloride and indicates the disappearance of excess Cu from circulation along with the carrier proteins and suggests a probable role of haemocyanin and haemocytes in transport ofExogenous heavy metals.
TL;DR: Thenus orientalis (Lund), the only species of the genus belonging to the family Scyllaridae, is found in the coastal waters of India where it breeds and molts throughout the year, with alternating peaks for molting and reproduction.
TL;DR: A review of hydrogen energy research in India and its growth during the first 10 years have already been reviewed at the VI-WHEC (Vienna, 1986) as discussed by the authors, which is an update of the previous report.
TL;DR: Examination of the state of mosquito-borne lymphatic filariasis in Madras, Tamil Nadu, in southern India during the 1970s and into the 1980s suggests that the disease is prevalent throughout the city to varying extents and that community health education is still inadequate.
TL;DR: Spore wall pigments from twelve species of myxomycetes, belonging to the orders Physarales and Stemonitales, and Liceales were extracted with 1 m -KOH and identified as melanin on the basis of various physico-chemical tests, ultraviolet and infrared spectra.
TL;DR: The present work was undertaken to understand the effect of ochratoxin A on glucose metabolism in rats and reported that ochRatoxin A ingestion is found to increase blood glucose in chicks.
Abstract: Ochratoxin A is a toxic secondary metabolite produced by several species of Aspergillus and Penicillium (Ciegler et al. 1972). The distribution of these fungi in the natural environment is extensive and are reported to contaminate a wide variety of foods and feeds (Prior 1976). Ochratoxin A has been reported to be hepatotoxic, teratogenic and nephrotoxic (Prior et al. 1983). Previously we have reported that ochratoxin A ingestion is found to increase blood glucose in chicks (Subramanian and Govindasamy 1985). Hence the present work was undertaken to understand the effect of ochratoxin A on glucose metabolism in rats.
TL;DR: In this paper, a separable potential model for the hyperon-nucleon interaction in conjunction with the Bethe-Goldstone equation for nuclear matter is used for the evaluation of the binding energy of Λ.
Abstract: A separable potential model for the hyperon-nucleon interaction in conjunction with the Bethe-Goldstone equation for nuclear matter is used for the evaluation of the binding energy of Λ. The results obtained under the various conditions are presented.
TL;DR: In this paper, two polyamides obtenus par reaction du dimethyl-2,2' diamino-4,4' azobenzene avec le chlorure de terephtaloyle and le chlorures d'azodibenzoyle-4.4'.
Abstract: Etude des 2 polyamides obtenus par reaction du dimethyl-2,2' diamino-4,4' azobenzene avec le chlorure de terephtaloyle et le chlorure d'azodibenzoyle-4,4'. Proprietes mecaniques superieures des fibres du polyamide contenant deux groupes azo par unite, qui permettent un empilement compact des chaines d'ou une coagulation plus lente et une densite de vides plus faible. Augmentation de la tenacite et du module initial par etirage a chaud des fibres
TL;DR: To assess the pathogenic significance of hepatitis B virus (HBV) in glomerulonephritis (GN), 98 patients with histopathologically proven glomerULonephropathies were screened for HBV markers, complement components and levels of circulating immune complexes (CICs); and renal biopsies from 31 of them were examined for the presence of HBsAg, and its location, by immunoperoxidase staining.
Abstract: To assess the pathogenic significance of hepatitis B virus (HBV) in glomerulonephritis (GN), 98 patients with histopathologically proven glomerulonephropathies were screened for HBV markers, complement components and levels of circulating immune complexes (CICs); and renal biopsies from 31 of them were examined for the presence of hepatitis B surface antigen (HBsAg), and its location, by immunoperoxidase staining. The HBsAg positive rate in the patients (who came from a population with 10% HBsAg positivity) ranged from 51.9% in minimum change nephrotic syndrome (MCNS) to 81.8% in patients with proliferative glomerulonephritis (PGN). Whereas 24.5% of the cases were positive for HBsAg only, 10.2% had anti-HBcIgM with HBsAg, 13.3% had HBeAg with HBsAg and 9.2% had HBsAg, HBeAg and anti-HBcIgM. Complement component C3 levels were decreased in all groups of GN studied, but C4 levels varied. CIC levels were significantly increased (p < 0.01) only in HBsAg-positive MCNS, focal glomerulosclerosis (FGS) and membranous glomerulonephritis (MGN). Of the 31 renal biopsies examined for the deposition of HBsAg, 4 (12.9%) were found to be positive for HBsAg in situ; 64.5% of biopsied patients were seropositive for HBsAg and 77.4% had CICs. All the four in-situ HBsAg-positive cases were seropositive for HBsAg, HBeAg and anti-HBcIgM with significantly high CIC levels (p<0.01). HBsAg deposition was intracytoplasmic in the mesangial cells of the glomeruli, in the glomerular basement membrane or in the tubules, or in a combination of these sites.
01 Jun 1989
TL;DR: Circadian and seasonal periodicities of 10 fungal spore types common in the atmosphere of Madras city are described from data obtained by sampling air with a Burkard model of the Hirst spore trap for a period of one year.
Abstract: Circadian and seasonal periodicities of 10 fungal spore types common in the atmosphere of Madras city are described from data obtained by sampling air with a Burkard model of the Hirst spore trap for a period of one year. The periodicity ofNigrospora conformed to ‘post-dawn pattern’;Alternaria, Drechslera, Curvularia, Torula to ‘mid-day pattern’;Cladosporium andPericonia to ‘double peak pattern’;Ganoderma, Coprinus andLeptosphaeria to ‘night pattern’. Maximum incidence of the spores were noticed in the atmosphere during August to December corresponding with the rainy season.
TL;DR: A tricyclic intermediate with the potentials to be elaborated to a A-ring aromatic or non-aromatic steroid system, bearing a methyl at C8 carbon, has been synthesized via an oxy-Cope rearrangement from the readily available α-tetralone as discussed by the authors.
TL;DR: The fungi elaborated catechol 1,2-dioxygenase, protocatechuic acid, hydroxyquinol, gent isic acid and homogentisic acid during growth on aromatic substances.
TL;DR: It is suggested that like ethanol, methanol also produces certain changes in the steady state level of monoamines in hypothalamus and striatum of albino rats and these changes could be attributed to the direct action of meethanol rather than to its metabolic end products like formaldehyde or formate.