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Digitale Medien

Relative status and contribution of sediment phosphorus and nitrogen in carp culture system fertilized with various combinations of rockphosphate (1997)

Jana, B B ; Chakrabarty, D

Oxford, UK : Blackwell Publishing Ltd

Aquaculture research 28 (1997), S. 0

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ISSN: 1365-2109

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Notizen: Growth performances of advanced fry of Indian major carps. Labeo rohita (Hamilton). Catla catla (Hamilton) and Cirrhinus mrigala (Hamilton), were examined in simulated pond systems using monthly application of the following fertilizers in six treatments: Mussoorie rockphosphate (MPR) in low (100 kg P2O5 ha−1) and high doses (200 kg P2O5 ha−1), single superphosphate (SSP) (50 kg P2O5 ha−1), single superphosphate mixed with rockphosphate (1:1 by weight: 50 kg P2O5), compost (C) (water hyacinth and cattle manure) and composted rockphosphate (MPR-C). The amount of available P in surface sediment of MPR-C did not differ from that in either the SSP or the MPR + SSP treatment, whereas the total and available N contents differed greatly. There was an inverse relationship between the time to reach phosphate peak of water and the retention time of fertilizer in surface sediments. It is evident that total P of surface sediment was the most significant contributor to fish growth in exclusively MPR treatments, whereas total P and total N of surface sediments are involved in the MPR treatments in combination with compost or SSP.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1046/j.1365-2109.1997.t01-1-00853.x

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Digitale Medien

Catalytic properties of vanadium bronzes, I. Decomposition of isopropanol (1977)

Chakrabarty, D. K. ; Guha, D.

Springer

Reaction kinetics and catalysis letters 6 (1977), S. 307-314

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ISSN: 1588-2837

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Beschreibung / Inhaltsverzeichnis: Abstract Разложение изопропанола на V2O5 и бронзах: Li0,02V2O5, Na0,02V2O5, Na0,06V2O5, Li0,33V2O5 и Na0,33V2O5 было исследовано в области температур 186–300°C. Для первых четырех катализаторов основной реакцией оказалась дегидратация до пропена с незначительной дегидрогенизацией до ацетона. Дегидратация на этих катализаторах увеличивается с содержанием щелочного металла, а энергия активации остается неизменной. На последних двух катализаторах дегидратация и дегидрогенизация протекают при сравнимых скоростях. Исходя из влияния продуктов на начальную скорость, данных электропроводимости катализаторов и их ЭПР спектров, предлагается механизм дегидратации изопропанола.

Notizen: Abstract Decomposition of isopropanol on V2O5 and the bonzes Li0.02V2O5, Na0.02V2O5, Na0.06V2O5, Li0.33V2O5, and Na0.33V2O5 has been studied in the temperature range 168–300°C. The main reaction was found to be dehydration to propene with negligible dehydrogenation to acetone on the first four catalysts. Dehydration on these catalysts increased with the alkali metal content, but the energy of activation remained unchanged. On the last two catalysts, dehydration and dehydrogenation proceeded at comparable rates. A tentative mechanism for the dehydration of isopropanol is proposed, based on the effect of the product on the initial rate, the electric conductivity of the catalysts and their ESR spectra.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02070225

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Digitale Medien

Dehydrogenation of 2-propanol on doped nickel oxide catalysts (1979)

Chakrabarty, D. K. ; Bheema Raju, V. ; Biswas, A. B.

Springer

Reaction kinetics and catalysis letters 11 (1979), S. 63-69

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ISSN: 1588-2837

Quelle: Springer Online Journal Archives 1860-2000

Thema: Chemie und Pharmazie

Beschreibung / Inhaltsverzeichnis: Abstract Были приготовлены образцы окиси никеля, насышенные литием и индием, с содержанием допанта до 3 ат.%-ов. Были исследованы электрические свойства этих образцов. Для всех образцов была обнаружена проводимость типа р, которая возрастает с литиевым насыщением и уменышается с индиевым насыщением. Дегидрирование 2-пропанола на этих катаизаторах уменьшается с увеличением концетрации дырок в твердом веществе. Ступенью, лимитирующей скорость процесса, является десорбция ацетона. Предлагается вероятный менанизм протекания процесса.

Notizen: Abstract Lithium and indium doped nickel oxide samples have been prepared with up to 3 at. % of dopant. The electrical properties of these samples have been studied. All the samples exhibit p-type conductivity which increases with lithium doping and decreases upon doping with indium. Dehydrogenation of 2-propanol on these catalysts increases with the hole concentration in the solid. Desorption of acetone appears to be the rate-determining step. A possible mechanism for the reaction is proposed.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02098335

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Epoxy-poly(butyl methacrylate) interpenetrating polymer networks: Morphology and various physical, mechanical, and thermal properties (1996)

Chakrabarty, D. ; Das, B.

New York, NY [u.a.] : Wiley-Blackwell

Journal of Applied Polymer Science 60 (1996), S. 2125-2132

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ISSN: 0021-8995

Schlagwort(e): Chemistry ; Polymer and Materials Science

Quelle: Wiley InterScience Backfile Collection 1832-2000

Thema: Chemie und Pharmazie , Maschinenbau , Physik

Notizen: Semi- and full interpenetrating polymer networks (IPNs) of epoxy resin and poly(butyl methacrylate) (PBMA) were prepared by the sequential mode of synthesis. These were characterized with respect to their mechanical properties, such as ultimate tensile strength, percent elongation at break, and modulus. The densities of these samples were evaluated and compared. Differential scanning calorimetry (DSC) and thermogravimetric analysis were undertaken for thermal characterization of the IPNs. Phase morphology was studied by polarized light microscopy of the undeformed specimens and by scanning electron microscopy of the fractured surfaces of samples undergoing tensile failure. The effects of variations of the blend ratios on the above-mentioned properties were examined. A gradual decrease in modulus and tensile strength was observed for both the semi- and full IPNs with consequent increases in elongation at break and toughness as the proportion of PBMA increased. The densities also followed the same pattern. Semi-IPNs, however, were characterized by higher densities, tensile strengths, and moduli than the corresponding full IPNs. The DSC tracings displayed broadening of transitions, indicating some phase blending. The percent weight retentions in the thermal decomposition of the IPNs and pseudo-IPNs were higher than that observed during the thermal degradation of the epoxy resin homopolymer network. Phase-separated PBMA domains of various sizes were presumed to be responsible for the increased toughness of PBMA-modified epoxy. © 1996 John Wiley & Sons, Inc.

Zusätzliches Material: 7 Ill.

Materialart: Digitale Medien

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Digitale Medien

Electrical properties of vanadium pentoxide doped with lithium and sodium in the α-phase range (1976)

Chakrabarty, D. K. ; Guha, Dipak ; Biswas, A. B.

Springer

Journal of materials science 11 (1976), S. 1347-1353

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ISSN: 1573-4803

Quelle: Springer Online Journal Archives 1860-2000

Thema: Maschinenbau

Notizen: Abstract The electrical conductivity and Seebeck coefficients have been measured from room temperature to 500° C for polycrystalline V2O5 and V2O5 doped with lithium and sodium in the α-phase range. The conductivity increases with doping and the energy of activation decreases. The Seebeck coefficient indicates that electrons are the majority carriers. The results have been discussed in terms of the two-level hopping model.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF00545157

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