Showing papers by "Annamalai University published in 1993"
TL;DR: International comparison of residue levels in cetaceans in the recent decade revealed that DDT concentrations in Indian dolphins were comparable to those from other localities whereas PCB levels were low.
78 citations
TL;DR: In this article, a factor analysis of the elemental data identifies two major groups of heavy metals, (a) Fe, Mn, Cr, V and Ti and (b) Cu, Pb and Zn in the suspended sediments of Cauvery river.
Abstract: Heavy metal transport in Cauvery river chiefly takes place in the particulate form. Tributaries Hemevathi and Kabini draining highly mineralized areas contribute significantly to the heavy metal load of the Cauvery river. Particulate metal transport is influenced by the presence of major dams built across the river. Factor analysis of the elemental data identifies two major group of heavy metals, (a) Fe, Mn, Cr, V and Ti and (b) Cu, Pb and Zn in the suspended sediments of Cauvery river. Heavy metals in surface sediments show wide variations in their concentrations due to the non-uniform grain size distribution of the sediments. The elements Fe, Mn, Pb, Cu, Zn, Ni, Co and As are dominantly present in the <20 μm fraction of the river sediments. Speciation studies show that Fe-Mn oxide phase held the largest share of heavy metals in the sediments. The depth variation of heavy metals in the core sediments suggest their similar mobility during diagenesis. Geoaccumulation indices calculated suggest that Cd, Zn, Cr, Pb, Cu and Ni are enriched in sediments several times over background values.
59 citations
TL;DR: In this article, the major ion chemistry of water and elemental geochemistry of suspended and surficial sediments collected from the Cauvery Estuary were studied to understand the geochemical processes in this tropical estuarine system.
Abstract: Major ion chemistry of water and elemental geochemistry of suspended and surficial sediments collected from the Cauvery Estuary were studied to understand the geochemical processes in this tropical estuarine system. Specific conductance (EC), total dissolved solids (TDS), and total suspended matter (TSM) increased conservatively with increasing chlorinity. In general, SO4
2−, Na, K, Ca, and Mg showed an increasing trend while H4SiO4 and PO4
3− showed a decreasing trend toward the sea. Additional removal mechanisms operating for these ions in the Cauvery Estuary have been identified based on observed concentrations. Factor analysis pointed out the sources contributing to the observed trends in estuarine water chemistry. POC and PON decreased toward the high chlorinity zone. TSM in the Cauvery Estuary were mostly of inorganic nature. Stable carbon isotope values showed that the carbon was equally of marine and terrestrial origin and helped to delineate the contribution of river water and seawater. The ϕ mean size (a logarithmic grain size scale commonly used by sedimentologists) indicated that the surficial sediments were primarily comprised of coarse and silt, whereas suspended sediments were principally silt and clay. Suspended sediments were enriched in clays compared to surficial sediments. Quartz and feldspar were abundant among detritals while chlorite, kaolinite, and montmorillonite were dominant among clays. Silicon was the most abundant element in the sediments followed by Al, Ca, Na, K, Fe, Mn, and P. Heavy metals were enriched in the suspended sediments compared to the surficial bottom sediments as follows: Fe = 3.5, Mn = 7.4, Pb = 1.1, Zn = 15.2, Cu = 7.4, and Cr = 4.0. The levels of Cd, Cr, Zn, and Fe increased up the middle reaches and then decreased toward the sea due to urban effluent and fertilizer input. Size fractionation studies indicated that the metal concentration in the finer fraction was 50% higher by mass than the coarse silt and fine silt fractions. Chemical fractionation studies showed that the abundance of metals were in the order of residual > organic/sulfide > carbonate > Fe/Mn oxide > exchangeable fractions.
49 citations
TL;DR: In this paper, the dry matter yield of tissue showed highly significant reduction (at the 1% level) for Cd and Cu, and nonsignificant variation for Zn.
Abstract: Blackgram (Vigna mungo, L.) growth was measured in a glasshouse earthen‐pot experiment. Cadmium (Cd), copper (Cu), and zinc (Zn) were applied in different concentrations to the soil. The plant and soil samples were analysed 45 days after sowing using ICP‐AES. The dry matter yield of tissue showed highly significant reduction (at the 1% level) for Cd and Cu, and nonsignificant variation for Zn. This shows that phytotoxicity for Cd and Cu was greater than that for Zn. Further, the observed higher correlation coefficients suggest that the concentration of the elements in tissue is linearly related to that applied to the soil.
42 citations
TL;DR: A characterization is established for a graph G to have a Hamilton cycle in G × K2, the prism over G, and it is shown that every 3-connected graph has a 2-connected spanning bipartite subgraph.
Abstract: A characterization is established for a graph G to have a Hamilton cycle in G × K2, the prism over G. Moreover, it is shown that every 3-connected graph has a 2-connected spanning bipartite subgraph. Using this result, the existence of a Hamilton cycle in the prism over every 3-connected cubic graph is established. Further, the existence of a Hamilton cycle in the prism over a cubic 2-connected graph is also discussed. Earlier results in this direction are shown to be particular cases of the results obtained here. © 1993 John Wiley & Sons, Inc.
41 citations
27 citations
TL;DR: In viviparous hypocotyls of Rhizophora apiculata Blume the triacontanol treatment enhanced the growth of root and shoot, protein and energy contents of leaves and roots, in vivo nitrate reductase activity, contents of chlorophylls and carotenoids in leaves as well as the amount of chloropylls present in photosystems 1 and 2 and in the light harvesting complex of chloroplasts.
Abstract: In viviparous hypocotyls ofRhizophora apiculata Blume the triacontanol treatment enhanced the growth of root and shoot (number of primary and secondary roots, length of roots, shoot height and biomass) protein and energy contents of leaves and roots,in vivo nitrate reductase activity, contents of chlorophylls and carotenoids in leaves as well as the amount of chlorophylls present in photosystems 1 and 2 and in the light harvesting complex of chloroplasts. These promotory effects were recorded at 40 and 80 mg m-3 triacontanol, but they decreased with increasing growth regulator concentration.
23 citations
TL;DR: Perumal et al. as discussed by the authors studied the influence of meteorological phenomenon on the ecosystem of a tropical region, Southeast Coast of India, in a case study using Ciencias Marinas.
Abstract: Formato ISO 690-2 (Articulos de revistas electronicas) Perumal, P., The Influence Of Meteorological Phenomena On The Ecosystems Of A Tropical Region, Southeast Coast Of India: A Case StudyCiencias Marinas [en linea] 1993, 19 ( ) : [Fecha de consulta: 29 de diciembre de 2017] Disponible en: ISSN 0185-3880
21 citations
TL;DR: In this article, a CAD procedure for the optimum fool-proof design of explosive welding systems is proposed based on the basic requirements of explosive bonding and conditions favorable for producing acceptable strong welds.
18 citations
01 Oct 1993
TL;DR: The stilt root of Rhizophora apiculata was found most effective and gave protection against the biting of Aedes aegypti for 70 minutes at a dose of 1 mg dry plant extract per cm2 of skin.
Abstract: Four seaweeds (Caulerpa peltata, C. racemosa, C. scalpelliformis and Diclyota dichotoma) And eleven mangrove plant samples (the leaves of Avicennia marina, A. officinalis, Excoecaria agallocha, Lumnitzera racemosa, Rhizophora apiculata, R. lamarckii, R. mucronata, Salicornia brachiata, Sonneratia apetala, Xylocarpus granatum And the stilt root of Rhizophora apiculata) were extracted in acetone And tested on human skin for repellent activity against the biting of Aedes aegypti. The stilt root of Rhizophora apiculata was found most effective And gave protection for 70 minutes at a dose of 1 mg dry plant extract per cm2 of skin.
16 citations
TL;DR: He andPao's method of identifying specific discipline journals is improved by adding the citing impact factor and self-citing rate and this indicator paves the way to identify the constituent journals of a discipline.
Abstract: He andPao's method of identifying specific discipline journals is improved by adding the citing impact factor and self-citing rate. The proposed indicator strikes a balance by discounting the size of a discipline. And also this indicator paves the way to identify the constituent journals of a discipline. This method was tested in Physics, Applied Physics and Astronomy and Astrophysics. The findings lead to the rethinking about the inclusion of many journals in these fields.
TL;DR: In this article, the possibility of assigning the configuration of a substituent in six-membered ring compounds from the 13C chemical shifts of a single epimer was examined.
Abstract: The possibility of assigning the configuration of a substituent in six-membered ring compounds from the 13C chemical shifts of a single epimer was examined. The chemical shifts of the ring carbons in saturated six-membered ring compounds were calculated using standard substituent parameters obtained from tert-butyl systems, and these calculated values were compared with the observed values. It was found that in isomeric 1,3- and 1,4-disubstituted cyclohexanes the configuration could be assigned correctly for each isomer by comparing the observed chemical shifts with the calculated values, an exception being trans-1,3-dihydroxycyclohexane. However, in the 1,2-disubstituted cyclohexanes the configuration could be assigned correctly only by comparing the observed and calculated chemical shifts for the γ- or β-methylene carbons. The configuration cannot be assigned correctly in heterocyclic systems by using the individual chemical shifts as probes. However, when the sum of the chemical shifts of the ring carbons could be calculated for equatorial and axial orientations of the substituent using standard substituent parameters to a reasonable degree of accuracy, the configuration for any epimer could be assigned correctly by comparing the observed and calculated sums.
Journal Article•
TL;DR: The antibacterial activity of the extracts of bryozoan E. bellula (Hincks) was tested against ten bacterial strains by antibiotic disc diffusion method, and the maximum activity was observed against Proteus vulgaris.
Abstract: The antibacterial activity of the extracts of bryozoan E. bellula (Hincks) was tested against ten bacterial strains by antibiotic disc diffusion method. The maximum activity was observed against Proteus vulgaris, while Klebsiella pneumoniae and Shigella flexneri were insensitive to the bryozoan.
TL;DR: The feeding preference of coccinellid predators namely, Coccinella transversalis F. and Cheilomenes sexmaculatus F. on different instars and forms of the aphid, Aphis gossypii Glov.
Abstract: The feeding preference of two coccinellid predators namely, Coccinella transversalis F. and Cheilomenes sexmaculatus F. on different instars and forms of the aphid, Aphis gossypii Glov. and predator age-dependent interference on the rate of predation were investigated. Significant differences were observed among the predatory stages for various prey ages. Older predators fed on older preys. However, adult beetles did not show any marked preference and fed on all stages and forms of preys. The various combinations of adults and grubs at different levels significantly affected the prey consumption levels. Among the various treatments, the treatment with 12 predators consumed the maximum number of aphids at all prey levels followed by 12 adults + one instar grub indicating the addition of a grub did not increase the prey consumption of adults.
TL;DR: In this paper, some primary alcohols were oxidized by 2,2′-bipyridinium chromate (BPC) in the presence of oxalic acid and TsOH giving aldehyde as major product.
Abstract: Some primary alcohols were oxidized by 2,2′-bipyridinium chromate (BPC) in the presence of oxalic acid and TsOH giving aldehyde as major product. The reactions were carried out in 80% MeCN-DMF (v/v) medium under varied experimental conditions. The rate depends on the first power of the concentration of BPC and fractional power on the concentrations of alcohol, oxalic acid and TsOH.
TL;DR: In this article, the optimal grouping of the eample observations when the component densities belong to the family of densities possessing the monotone likelihood ratio property was proposed for the case of mixtures of two normal densities.
Abstract: Using the ‘grouping vector’ notion and employing a Dirichlet prior to the unknown mixing parameters viz., the unknown mixing proportiona, the Bayee estimates of the mixing proportions in finite mixtures of known distributions are obtained. These estimates are based on the optimal grouping of the sample data. An algorithm is proposed to obtain the optimal grouping of the eample observations when the component densities belong to the family of densities possessing the monotone likelihood ratio property. A numerical study is carried out for the case of mixtures of two normal densities.
TL;DR: In this article, the steric effect of ortho-substituents has been analyzed in the light of application of Taft's steric energy parameters and a good correlation is found between log k1 and Hammett constants.
Abstract: The kinetics of oxidation of ethyl S-phenylmercapto acetate and several para-, meta-, and ortho-substituted ethyl S-phenylmercaptoacetates by chloramine-B have been studied in 50% (V/V) aqueous ethanol medium containing phosphate buffer. This oxidation is of first order with respect to substrate and zero order with respect to oxidant. A catalytic effect of mercury is observed and the order with respect to mercury is fractional (0.74). The increase in pH decreases the rate of oxidation and the order with respect to H+ is 0.05. In general electron-releasing substituents accelerate the rate while electron-attracting groups retard the rate. A good correlation is found to exist between log k1 and Hammett constants. Susceptibility of the reaction to the steric effect of ortho-substituents has been analyzed in the light of application of Taft's steric energy parameters. © John Wiley & Sons, Inc.