| Abstract: | We report enhanced back scattering in nanometer-sized ZnO colloids prepared in two different media, by different methods. The FWHM of the back scattered cone and hence the mean free path varied with concentration of ZnO as well as particle size. The Lorentzian profile of backscattered cone indicates the presence of coherence. |
| URI: | http://dyuthi.cusat.ac.in/purl/2587 |
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| Dyuthi-P0147.pdf | (255.6Kb) |
| Abstract: | Light-scattering experiments gained prominence as potential applications of quantum optics, nonlinear optics, and photon localization. The possibility of the realization of lasing action in random media has created much interest in the study of the coherent structure of the backscattered light from disordered media. Backscattering (BS) studies are carried out to analyze the possibilities of photon localization in colloidal silica. The scattering enhancement is best associated with the density of the scatterers. The width of the BS cone and, hence, the mean-free path is related to the concentration of the medium. The dependence of the photon wavelength on the possible characteristics of the scattering is presented. |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/2041 |
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| Backscattering of laser light...pdf | (179.0Kb) |
| Abstract: | Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (.SCS) is reported. This technique is found lo be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method |
| URI: | http://dyuthi.cusat.ac.in/purl/1365 |
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| Backscattering ... rs using SCS technique.PDF | (1.362Mb) |
| Abstract: | Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (SCS) is reported. The technique is found to be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method. |
| URI: | http://dyuthi.cusat.ac.in/purl/1573 |
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| Backscattering ... rs using SCS technique.PDF | (1.362Mb) |
| Abstract: | Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (SCS) is reported. The technique is found to be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method. |
| URI: | http://dyuthi.cusat.ac.in/jspui/handle/dyuthi/1575 |
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| Backscattering ... rs using SCS technique.PDF | (1.362Mb) |
| Abstract: | Reduction of radar cross -section of dihedral corner reflectors using simulated corrugated surface (SCS) is reported. The technique is found to be more effective in the reduction of RCS or corner reflectors for normal incidence . A typical reduction of 40-50 dB is achieved using this method. |
| URI: | http://dyuthi.cusat.ac.in/purl/1574 |
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| Backscattering ... rs using SCS technique.PDF | (1.362Mb) |
| Abstract: | The electron donating properties of La2O3 activated at 300, 500 and 800·C and its mixed oxides with alumina are reported from the studies on adsorption of electron acceptors of varying electron affinity on La203. The electron acceptors with their electron affinity values given in parenthesis are: 7,7,8,8-tetracyanoquinodimethane (2.84 eV), 2,3,5,6-tetrachloro-I,4-benzoquinone (2.40 eV) and p-dinitrobenzene(l.77eV). The basicity of the oxide has been determined by titration with n-butylamine and Ho.max values are reported. The limit of electron transfer from the oxide to the electron acceptor is between 2.40 and 1.77 eV. It is observed that La203 promotes the surface electron properties of alumina without changing its limit of electron transfer. |
| URI: | http://dyuthi.cusat.ac.in/purl/2217 |
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| Dyuthi-SS22.pdf | (236.1Kb) |
| Abstract: | A new microwave dielectric resonator Ba(Tb1/2Nb1/2)03 has been prepared and characterized in the microwave frequency region. 1 wt% CeO2 is used as additive to reduce the sintering temperature. The sintered samples were characterized by XRD, SEM and Raman spectroscopic methods. Microwave DR properties such as er, Q factor and temperature-coefficient of resonant frequency (Ti) have been measured using a HP 8510 B Network Analyzer. Cylindrical DRs of Ba(Tb1/2Nbi/2)03 showed high Er (~ 37), high Q (~3,200) and low Tf (~10 ppm /°C) at 4 GHz and hence are useful for practical applications |
| URI: | http://dyuthi.cusat.ac.in/purl/1447 |
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| Ba(Tb1 2Nb1 2)0 ... e dielectric resonator.PDF | (2.173Mb) |
| Abstract: | In this paper, a novel application of solid acid catalysts in the Beckmann rearrangement of E,E-cinnamaldoxime in the synthesis of an important heterocyclic compound; isoquinoline is reported. E,E-Cinnamaldoxime under ambient reaction conditions on zeolite catalysts underwent Beckmann rearrangement to produce isoquinoline in yields of ca. 86–95%. Cinnamonitrile and cinnamaldehyde were formed as by-products. LaH-Y zeolite produces maximum amount of the desired product (yield 95.6%). However, the catalysts are susceptible for deactivation due to the basic nature of the reactants and products, which neutralize the active sites. H-Y zeolite is more susceptible (22% deactivation in 10 h) for deactivation compared to the cerium-exchanged counterpart (18% deactivation in 10 h). Thus, the optimal protocol allows isoquinoline to be synthesised in excellent yields through the Beckmann rearrangement of cinnamaldoxime. The reaction is simple, effective, does not involve any other additives, and environmentally benign. |
| URI: | http://dyuthi.cusat.ac.in/purl/2315 |
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| Dyuthi-SS83.pdf | (457.2Kb) |
| Abstract: | Chaotic synchronization of two directly modulated semiconductor lasers with negative delayed optoelectronic feedback is investigated and this scheme is found to be useful for e±cient bidirectional communication between the lasers. A symmetric bidirec- tional coupling is identified as a suitable method for isochronal synchronization of such lasers. The optimum values of coupling and feedback strength that can provide maxi- mum quality of synchronization are identified. This method is successfully employed for encoding/decoding both analog and digital messages. The importance of a symmetric coupling is demonstrated by studying the variation of decoding efficiency with respect to asymmetric coupling. |
| URI: | http://dyuthi.cusat.ac.in/purl/2525 |
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| Dyuthi-P0100.pdf | (1.173Mb) |
| Abstract: | We have studied the bifurcation structure of the logistic map with a time dependant control parameter. By introducing a specific nonlinear variation for the parameter, we show that the bifurcation structure is modified qualitatively as well as quantitatively from the first bifurcation onwards. We have also computed the two Lyapunov exponents of the system and find that the modulated logistic map is less chaotic compared to the logistic map. |
| URI: | http://dyuthi.cusat.ac.in/purl/2562 |
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| Dyuthi-P0121.pdf | (521.1Kb) |
| Abstract: | Hydroxyapatite (HAp, Ca10(PO4)6(OH)2) bioceramic and chitosan (poly [( -1-4) D-glucosamine]) biopolymer show good biocompatibility in vivo. They have biological origin and show excellent interactions with microwave. Microwave study of HAp made using different drying techniques and their composites with chitosan in the ISM band is presented. Pastes are made using HAp and chitosan with different ratios of mixing. The dielectric properties of this composites match with that of human fat, collagen tissues. Some of the compositions exhibit dielectric property close to that of natural bone. This makes them more biocompatible and better substitutes for natural bone. Thus composite bioceramics can be considered as phantom model constituents for imaging purposes. Their dielectric properties prove that they are biocompatible. |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/2050 |
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| Biocompatibilit ... oxyapatite-chitosan....pdf | (306.1Kb) |
| Abstract: | Even though continental margins cover only about 7–9% of the world ocean area, they are important sites for organic carbon accumulation and hence play a major role in biogeochemical carbon cycling. Surface sediments from the western and eastern continental shelves of India were studied for their total organic matter content and the labile constituents such as total carbohydrates and proteins to get a better understanding of the hydrological and biogeochemical differences of the two regions on the nature of organic matter reaching the surface sediments. The sampling along the west coast was done during September–October 2003, when upwelling signatures were found to be still persisting along the shelf as evidenced by the low-oxygenated, nutrient-rich surface waters. The eastern shelf was sampled during November–December 2002. The shelf was found to be oxygen saturated and oligotrophic during the season. The surface sediments of the west coast contained a greater quantity of total organic matter when compared to the east coast, but the percentages of labile constituents of total organic matter in the sediments were found to be higher in the east coast by a factor of three as compared to the west coast. The differences in the productivity patterns and the hydrographical conditions were found to exert a major influence on the quantity and composition of organic matter in the surface sediments of the western and eastern continental shelves of India. |
| URI: | http://hdl.handle.net/purl/1888 |
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| Biogeochemistry ... diments of the Western.pdf | (479.2Kb) |
| Abstract: | Budidaya menghasilkan sejumlah besar limbah, terdiri dari metabolisme oleh-produk, makanan sisa, materi feses dan residu dari masukan profilaksis dan terapeutik, mengarah pada penurunan kualitas air dan wabah penyakit. Bioremediasi, aplikasi mikroba / enzim untuk tambak, adalah metode yang sedang digunakan untuk meningkatkan kualitas air dan menjaga kesehatan dan stabilitas sistem akuakultur. Bioremediasi melibatkan mineralisasi bahan organik menjadi karbon dioksida, memaksimalkan produktivitas primer yang merangsang produksi udang, nitrifikasi dan denitrifikasi untuk (1) menghilangkan kelebihan nitrogen dari tambak dan (2) mempertahankan beragam dan stabil masyarakat kolam dimana patogen dikeluarkan dari sistem dan spesies diinginkan mendapatkan didirikan. Selain dari bahan organik merendahkan (detritivorous) bakteri heterotrofik, nitrifikasi, bakteri denitrifikasi dan fotosintesis umumnya digunakan dalam bioremediasi. |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/2032 |
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| Bioremediation in shrimp....pdf | (135.7Kb) |
| URI: | http://dyuthi.cusat.ac.in/purl/741 |
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| Padma Nambisan, ... intervention..,Nov2007.PDF | (1.918Mb) |
| Abstract: | A bivariate semi-Pareto distribution is introduced and characterized using geometric minimization. Autoregressive minification models for bivariate random vectors with bivariate semi-Pareto and bivariate Pareto distributions are also discussed. Multivariate generalizations of the distributions and the processes are briefly indicated. |
| URI: | http://dyuthi.cusat.ac.in/xmlui/purl/2104 |
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| Bivariate semi-Pareto distributions....pdf | (446.2Kb) |
| Abstract: | Blends of polychloroprene rubber and plasticized polyvinylchloride have been prepared in various compositions and their properties evaluated. The properties of the blends show that they can be used to replace polychloroprene in many applications |
| URI: | http://dyuthi.cusat.ac.in/purl/826 |
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| K E George and others,Blends of...,Dec1986.PDF | (4.998Mb) |
| Abstract: | 5-HT2A receptor binding parameters were studied in the cerebral cortex and brain stem of control, diabetic, insulin, insulin + tryptophan and tr3yptophan treated streptozotocin diabetic rats. Scatchard analysis using selective antagonist, [-H](±)2,3-dimethoxyphenyl-l-[2-(4-piperidine)- methanol] ([3H]MDL100907) in cerebral cortex of diabetic rats showed a significant decrease in dissociation constant (Kd) without any change in maximal binding (Bm). Competition binding studies in cerebral cortex using ketanserin against [3H]MDL100907 showed the appearance of an additional site in the low affinity region during diabetes. In the brain stem, Scatchard analysis showed a significant increase in Bmax and Kd. Displacement studies showed a shift in the receptor affinity towards a low affinity state. All these altered parameters in diabetes were reversed to control level by insulin, insulin + tryptophan and tryptophan treatments. Tryptophan treatment is suggested to reverse the altered 5-HT2Abinding and blood glucose level to control status by increasing the brain 5-HT content. |
| URI: | http://dyuthi.cusat.ac.in/purl/645 |
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| jakson James and C S P(2000)mayPDF.PDF | (5.042Mb) |
| Abstract: | Kinetic parameters of brain glutamate dehydrogenase (GDH) were compared in the brain stem, cerebellum and cerebral cortex of three weeks and one year old streptozotocin (STZ) induced four day diabetic rats with respective controls. A single intrafemoral dose of STZ (60mg/Kg body weight) was administered to induce diabetes in both age groups. After four days the blood glucose levels showed a significant increase in the diabetic animals of both age groups compared with the respective controls. The increase in blood glucose was significant in one year old compared to the three weeks old diabetic rats. The Vmm of the enzyme was decreased in all the brain regions studied, of the three weeks old diabetic rats without any significant change in the Km. In the adult the Vmax of GDH was increased in cerebellum and brain stem but was unchanged in the cerebral cortex. The K. was unchanged in cerebellum and cerebral cortex but was increased in the brain stem. These results suggest there may be an important regulatory role of the glutamate pathway in brain neural network disturbances and neuronal degeneration in diabetes as a function of age. |
| URI: | http://dyuthi.cusat.ac.in/purl/595 |
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| M P Biju and C S Paulose(1998) jan.PDF | (4.254Mb) |
| Abstract: | A novel cavity perturbation technique using coaxial cavity resonators for the measurement of complex permittivity of liquids is presented. The method employs two types of resonators (Resonator I and Resonator II). Resonator I operates in the frequency range 600 MHz-7 GHz and resonator II operates in the frequency range 4 GHz-14 GHz. The introduction of the capillary tube filled with the sample liquid into the coaxial resonator causes shifts in the resonance frequency and loaded Q-factor of the resonator. The shifts in the resonance frequency and loaded Q-factor are used to determine the real and imaginary parts of the complex permittivity of the sample liquid, respectively. Using this technique, the dielectric parameters of water and nitrobenzene are measured. The results are compared with those obtained using other standard methods. The sources of errors are analyzed. |
| URI: | http://dyuthi.cusat.ac.in/purl/2981 |
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| Dyuthi-P00416.pdf | (750.3Kb) |
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