Now showing items 2288-2297 of 2297
| Abstract: | ABSTRACT: Zinc salts of ethyl, isopropyl, and butyl xanthates were prepared in the laboratory. They were purified by reprecipitation and were characterized by IR, NMR, and thermogravimetric analysis techniques. The melting points were also determined. The rubber compounds with different xanthate accelerators were cured at temperatures from 30 to 150°C. The sheets were molded and properties such as tensile strength, tear strength, crosslink density, elongation at break, and modulus at 300% elongation were evaluated. The properties showed that all three xanthate accelerators are effective for room temperature curing. |
| URI: | http://dyuthi.cusat.ac.in/purl/870 |
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| Shiny Palaty an ... ccelerators..March2000.PDF | (4.150Mb) |
| Abstract: | The Young’s modulus and Poisson’s ratio of high-quality silicon nitride films with 800 nm thickness, grown on silicon substrates by low-pressure chemical vapor deposition, were determined by measuring the dispersion of laser-induced surface acoustic waves. The Young’s modulus was also measured by mechanical tuning of commercially available silicon nitride cantilevers, manufactured from the same material, using the tapping mode of a scanning force microscope. For this experiment, an expression for the oscillation frequencies of two-media beam systems is derived. Both methods yield a Young’s modulus of 280–290 GPa for amorphous silicon nitride, which is substantially higher than previously reported (E5146 GPa). For Poisson’s ratio, a value of n 50.20 was obtained. These values are relevant for the determination of the spring constant of the cantilever and the effective tip–sample stiffness |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/2029 |
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| Young's modulus of Silicon...pdf | (90.78Kb) |
| Abstract: | The asymmetric unit of the title compound, C11H8N4, contains two independent molecules. In the crystal structure, intermolecular N—H.....N hydrogen bonds link molecules into ribbons extended in the [100] direction |
| URI: | http://dyuthi.cusat.ac.in/purl/1643 |
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| acta e varsha.pdf | (213.4Kb) |
| Abstract: | Co(II), Ni(II) and Cu(II) complexes of dimethylglyoxime and N,N-ethylenebis(7-methylsalicylideneamine) have been synthesized in situ in Y zeolite by the reaction of ion-exchanged metal ions with the flexible ligand molecules that had diffused into the cavities. The hybrid materials obtained have been characterized by elemental analysis, SEM, XRD, surface area, pore volume, magnetic moment, FTIR, UV-Vis and EPR techniques. Analysis of data indicates the formation of complexes in the pores without affecting the zeolite framework structure, the absence of any extraneous species and the geometry of encapsulated complexes. The catalytic activities for hydrogen peroxide decomposition and oxidation of benzyl alcohol and ethylbenzene of zeolite complexes are reported. Zeolite Cu(II) complexes were found to be more active than the corresponding Co(II) and Ni(II) complexes for oxidation reactions. The catalytic properties of the complexes are influenced by their geometry and by the steric environment of the active sites. Zeolite complexes are stable enough to be reused and are suitable to be utilized as partial oxidation catalysts. |
| URI: | http://dyuthi.cusat.ac.in/jspui/handle/dyuthi/1639 |
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| xavier.pdf | (237.5Kb) |
| Abstract: | This thesis deals with the synthesis, characterization and catalysis activity studies of some zeolite encapsulated complexes. Encapsulation inside the zeolite cages makes the catalysts more stable. Further, the framework prevents the complexes from dimerising. Catalysis by metal complexes encapsulated in the cavities of zeolites and other molecular sieves has many features of homogeneous, heterogenous and enzymatic catalysis. Serious attempts has been made to gain product selectivity in catalysis .The catalytic activity shown by the encapsulated complexes can be correlated to the structure of the active site inside the zeolite pore. It deals with the studies on the partial oxidation of benzyl alcohol to benzaldehyde. The oxidatio was carried out using hydrogen peroxide as oxidant in presence of PdYDMG and CuYSPP as catalysts. The product (benzaldehyde) was detected using TLC and confirmed using GC.The catalytic activity of the complexes was tested for oxidation under various conditions. The operating conditions like the amount of the catalyst, reaction time, oxidant to substrate ratio, reaction temprature, and solvents have been optimized. No further oxidation products were obtained on continuing the reaction for four hours beyond the optimum time. Maximum conversion was obtained at room temperature and the percentage conversion decreased with increase in temperature. Activity was found to be dependent on the solvent used. With increasing awareness about the dangers of environmental degradation, research in chemistry is getting increasing geared to the development of “green chemistry,” by designing environmentally friendly products and processes that bring down the generation and use of hazardous substances. |
| URI: | http://dyuthi.cusat.ac.in/purl/7 |
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| Dyuthi-T0348.pdf | (8.523Mb) |
| Abstract: | The work presented in this thesis is mainly centered on the synthesis and characterization of some encapsulated transition metal complexes and the catalytic activity of the synthesized complexes in certain organic reactions.thesis deals with the catalytic activity of ruthenium-exchanged zeolite and the zeolite encapsulated complexes of SSC, SOD, SPD, AA, ABA, DMG, PCO, PCP, CPO and CPP in the hydroxylation of phenol using hydrogen peroxide. The products were analyzed with a GC to determine the percentage conversion and the chromatograms indicate the presence of different products like hydroquinone, catechol,benzoquinone, benzophenone etc. The major product formed is hydroquinone. From the screening studies, RuYSSC was found to be the most effective catalyst for phenol hydroxylation with 94.4% conversion and 76% hydroquinone selectivity. The influence of different factors like reaction time, temperature, amount of catalyst, effect of various solvents and oxidant to substrate ratio in the catalytic activity were studied in order to find out the optimum conditions for the hydroxylation reaction. The influence of time on the percentage conversion of phenol was studied by conducting the reactions for different durations varying from one hour to four hours. There is an induction period for all the complexes and the length of the induction period depends on the nature of the active components. Though the conversion of phenol and selectivity for hydroquinone. increases with time, the amount of benzoquinone formed decreases with time. This is probably due to the decomposition of benzoquinone formed during the initial stages of the reaction into other degradation products like benzophenones. The effect of temperature was studied by carrying out the reaction at three different temperatures, 30°C, 50°C and 70°C. Reactions carried at temperatures higher than 70°C result either in the decomposition of the products or in the formation of tarry products. Activity increased with increase in the amount of the catalyst up to a certain level. However further increase in the weight of the catalyst did not have any noticeable effect on the percentage conversion. The catalytic studies indicate that the oxidation reaction increases with increase in the volume of hydrogen peroxide till a certain volume. But further increase in the volume of H202 is detrimental as some dark mass is obtained after four hours of reaction. The catalytic activity is largely dependent on the nature of the solvent and maximum percentage conversion occurred when the solvent used is water. The intactness of the complexes within the zeolite cages enhances their possibility of recycling and the activities of the recycled catalysts show only a slight decrease when compared to the fresh samples . |
| Description: | Department of Applied Chemistry, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3007 |
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| Dyuthi-T0987.pdf | (7.244Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1163 |
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| Dyuthi-T0335.pdf | (9.730Mb) |
| Haridas P,1984.pdf | (73.15Kb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1543 |
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| Haridas P 1984.PDF | (373.3Kb) |
| Zooplankton stu ... environs-Bibliography.PDF | (8.628Mb) |
| Zooplankton stu ... environs-Bibliography.PDF | (8.628Mb) |
| Zooplankton stu ... Community structures-5.PDF | (2.937Mb) |
| Zooplankton stu ... chin environs-figures1.PDF | (6.760Mb) |
| Zooplankton stu ... chin environs-figures2.PDF | (15.91Mb) |
| Zooplankton stu ... nvirons- Hydrography-3.PDF | (7.251Mb) |
| Zooplankton stu ... virons- INTRODUCTION-1.PDF | (7.364Mb) |
| Zooplankton stu ... Materials and Method-2.PDF | (3.504Mb) |
| Zooplankton stu ... s- Species diversity-7.PDF | (2.912Mb) |
| Zooplankton stu ... inance and sucession-6.PDF | (2.870Mb) |
| Zooplankton stu ... hin environs-Summary-9.PDF | (4.354Mb) |
| Zooplankton stu ... cochin environs-Tables.PDF | (24.56Mb) |
| Zooplankton stu ... nvirons- Zooplankton 4.PDF | (23.88Mb) |
| Zooplankton stu ... plankton Assemblages-8.PDF | (3.756Mb) |
| Description: | International School of Photonics, Cochin University of Science & Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2184 |
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| Dyuthi-T0534.pdf | (4.924Mb) |
| Abstract: | The present study is focused on the production, purification and characterization of multiple thermostable α-galactosidases from a novel actinomycete strain Streptomyces griseoloalbus. The Chapter I of the thesis covers the wide literature regarding α-galactosidases from various sources and their potential applications. The Chapter 11 deals with the isolation of α-galactosidase- producing actinomycetes and selection of the best strain. The Chapters III and IV describe the optimization of α-galactosidase production under submerged fermentation and solid-state fermentation respectively. The Chapter V describes the purification and characterization of multiple α-galactosidases and also the obvious existence of a novel galactose-tolerant enzyme. The Chapter VI illustrates the potential applications of α-galactosidases from S. griseoloalbus followed by the Chapter VII summarizing and concluding the results of the present investigation. |
| URI: | http://dyuthi.cusat.ac.in/purl/2920 |
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| Dyuthi-T0911.pdf | (12.64Mb) |
Now showing items 2288-2297 of 2297
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