Showing papers by "Cochin University of Science and Technology published in 2000"
TL;DR: TLR2 stimulation by Staphylococcus aureus induces a fast and transient activation of the Rho GTPases Rac1 and Cdc42 in the human monocytic cell line THP-1 and in 293 cells expressing TLR2, and Rac1 controls a second, IκB–independent, pathway to NF-κB activation and is essential in innate immune cell signaling via TLR 2.
Abstract: Mammalian Toll-like receptors (TLRs) are expressed on innate immune cells and respond to the membrane components of Gram-positive or Gram-negative bacteria. When activated, they convey signals to transcription factors that orchestrate the inflammatory response. However, the intracellular signaling events following TLR activation are largely unknown. Here we show that TLR2 stimulation by Staphylococcus aureus induces a fast and transient activation of the Rho GTPases Rac1 and Cdc42 in the human monocytic cell line THP-1 and in 293 cells expressing TLR2. Dominant-negative Rac1N17, but not dominant-negative Cdc42N17, block nuclear factor-κB (NF-κB) transactivation. S. aureus stimulation causes the recruitment of active Rac1 and phosphatidylinositol-3 kinase (PI3K) to the TLR2 cytosolic domain. Tyrosine phosphorylation of TLR2 is required for assembly of a multiprotein complex that is necessary for subsequent NF-κB transcriptional activity. A signaling cascade composed of Rac1, PI3K and Akt targets nuclear p65 transactivation independently of IκBα degradation. Thus Rac1 controls a second, IκB–independent, pathway to NF-κB activation and is essential in innate immune cell signaling via TLR2.
653 citations
TL;DR: In this article, a review of the hydrography, floral and faunal composition of the Cochin backwaters is presented and an attempt to critically evaluate the status of the backwaters from the biological and pollutional stand point is also done.
Abstract: On the south west coast of India, there is an extensive estuarine system of backwaters, of which Vembanad Lake is the largest. The backwaters of Kerala support as much biological productivity and diversity as tropical rain forests. They are responsible for the rich fisheries potential of Kerala. Cochin backwaters situated at the tip of the northern Vembanad lake is a tropical positive estuarine system extending between 9° 40′ and 10° 12′N and 76° 10' and 76° 30′ E with its northern boundary at Azheekode and southern boundary at Thannirmukham bund. The lake has a length of 80 km and the width varies between 500 and 4000 m. A channel, about 450 m wide at Cochin gut and another at Azheekode, make permanent connections with the Arabian Sea. The depth of the estuary varies considerably. While the shipping channels are maintained at a depth of 10–13 m, the major portion of the estuary has a depth range of 2–7 m. Water from two major rivers viz., Periyar and Muvattupuzha drain into this estuary. During south west monsoon, the estuary is virtually converted into a freshwater basin even in areas around barmouth where salt water penetration occurs below 5 m depth only. The major hydrological variable in the Cochin backwaters is salinity, similar to the situations encountered in estuaries with a gradual declension of salinity from 30 at the entrance of the estuary to 0.2 at the point of entry of the rivers. Salinity gradient in the Cochin backwaters supports diverse species of flora and fauna depending on their capacity to tolerate oligohaline, mesohaline or marine conditions. Low lying swamps and tidal creeks, dominated by sparse patches of mangroves with their nutrient rich physical environment, support larvae and juveniles of many economically important species. Backwaters also act as nursery grounds of commercially important prawns and fishes. The fields around the backwater are suitable for aquaculture. These areas support traditional, seasonal and perennial prawn fishery. The changes in the hydrology controlled by the seasons play an important role in regulating the migrant fauna of the estuary. The Cochin backwater supports a well established endemic fauna. The nutrients and pollutants introduced into the estuary control to a great extent the distribution and abundance of less tolerant species in ecologically sensitive areas in the backwaters. Cochin backwaters, widely regarded as one of the polluted estuaries in India, receive contaminated freshwater inputs and discharges of effluents and partially treated sewage from many points throughout its tidally mixed zone. Recently, changes brought about in the estuary like reclamation and consequent shrinkage of the backwaters and the discharge of pollutants have made an adverse impact on the potential of aquatic ecosystems that used to support high levels of bioproductivity and biodiversity. The construction of Thannirmukham bund and Thottapally spillway to prevent salt water penetration into the paddy fields during pre-monsoon has led to serious ecological problems by interrupting the natural ebb and flow of tides. The hydrography, floral and faunal composition – its spatial and temporal variation plus assessments of the impact of the anthropogenic activities are presented in this review. An attempt to critically evaluate the status of the estuary from the biological and pollutional stand point is also done.
227 citations
TL;DR: This study demonstrates the potential usefulness of DXA to supply accurate measurements of VAT in addition to total body composition determination in obese subjects.
Abstract: OBJECTIVE: To get accurate measurements of visceral adipose tissue (VAT) using dual energy X-ray absorptiometry (DXA). DESIGN: DXA and anthropometric data and their combinations were compared to the VAT area calculated from a computed tomography (CT) single scan. SUBJECTS: 71 overweight subjects (44 women, 27 men), age: 16–70 y, BMI: 27–52 kg/m2. MEASUREMENTS: Total body and segmental tissue composition, and new parameters obtained from DXA, in addition to waist and hip cicumferences and abdominal sagittal diameter measurements. RESULTS: The ratio measured at the umbilical level (sagittal diameter−subcutaneous fat width)×(transverse internal diameter)/(height) was closely related to VAT (r=0.94 for women and 0.88 for men). It gave the most predictive equation for VAT: y=79.6x (s.e. 3.9)−149 cm2 for the whole population (r2=0.86, P<0.0001, root mean square error=38.2 cm2. An independent relationship between lean mass or its index (r=0.52 and 0.72, P<0.001) and VAT was also found in women. CONCLUSION: This study demonstrates the potential usefulness of DXA to supply accurate measurements of VAT in addition to total body composition determination in obese subjects.
123 citations
TL;DR: Extracellular l -glutaminase production by Beauveria sp., isolated from marine sediment, was observed during solid state fermentation using polystyrene as an inert support as mentioned in this paper.
94 citations
TL;DR: In this article, the preparation of copper selenide thin films using chemical bath deposition (CBD) technique is observed that the pH of the final reacting mixture is the major factor controlling the composition of the film.
66 citations
TL;DR: In this paper, a microwave dielectric ceramic resonators based on BaCe2Ti5015 and Ba5Nb4O15 have been prepared by conventional solid state ceramic route.
65 citations
TL;DR: In this paper, the properties of natural rubber/reclaimed rubber blends were studied and the minimum torque values of the blends were lower than that of the gum compound and the cure rate was lower than those of the virgin compounds.
Abstract: Cure characteristics and mechanical properties of natural rubber/reclaimed rubber blends were studied. The minimum torque values of the blends were lower than that of the gum compound. The (maximum–minimum torque) and scorch time decreased with increasing reclaim content. The cure rate of the blends were lower than that of the virgin compounds. The tear strength was improved by the addition of reclaimed rubber. Tensile strength, elongation at break, and resilience decreased with increasing reclaim loading. The heat buildup was higher for the blends.
47 citations
TL;DR: A novel cavity perturbation technique using coaxial cavity resonators for the measurement of complex permittivity of liquids is presented and the dielectric parameters of water and nitrobenzene are measured.
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.
46 citations
TL;DR: HIV infection did not affect the alfa-interferon treatment response of chronic hepatitis C, and response could be achieved among HIV-coinfected patients, which suggests a need to study whether HIV infection is associated with a worsening course of Chronic hepatitis C.
40 citations
TL;DR: In this paper, the conversion of CBD Cu x S films into CuInS 2 films was reported and it was shown that when pure indium is evaporated over these films and the samples are subsequently annealed, the film improves in crystallinity and shows major peaks of CuS 2.
38 citations
TL;DR: The ability of bacterins and an extracellular glue an-producing yeast to increase the overall survival and metamorphosis of larvae in a hatchery, as well as to protect against an experimental challenge under laboratory conditions, was evaluated.
TL;DR: In this paper, the physical and optical properties of various free base and metallic phthalocyanine (Pc) doped glass matrix are reported for the first time, and the spectra obtained are analyzed in the 2.1-6.2 eV region to obtain the optical band gap and the width of the band tail.
Abstract: Physical and optical properties of various free base and metallic phthalocyanine (Pc) doped glass matrix are reported for the first time. Absorption spectral measurements of H2Pc, MnPc, NiPc, CoPc, CuPc, MoOPc, ZnPc and FePc doped borate glass matrix have been made in the 200–1100 nm region and the spectra obtained are analyzed in the 2.1–6.2 eV region to obtain the optical band gap (Eg) and the width of the band tail (Et). Other important optical and physical parameters viz. refractive index (n), molar extinction coefficient (∈), density (ρ), glass transition temperature (Tg), molecular concentration (N), polaron radius (rp), intermolecular separation (R), molar refractivity (Rm) are also reported.
TL;DR: In this paper, a simple and efficient method for determining the complex permittivity of dielectric materials from both reflected and transmitted signals is presented, which is implemented using two pyramidal horns without any focusing mechanisms.
Abstract: A simple and efficient method for determining the complex permittivity of dielectric materials from both reflected and transmitted signals is presented. It is also novel because the technique is implemented using two pyramidal horns without any focusing mechanisms. The dielectric constant of a noninteractive and distributive (NID) mixture of dielectrics is also determined. © 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 26: 117–119, 2000.
TL;DR: In this article, gravity anomalies constrained by seismic data have been used to examine the long-term mechanical properties of the lithosphere beneath the Krishna-Godavari basin, a deltaic sedimentary basin on the eastern continental margin of India.
TL;DR: In this paper, a mild and efficient method for the stereoselective dehydration of α-aldoximes to the corresponding nitriles is described which utilises methyl (carboxysulfamoyl)triethylammonium hydroxide inner salt (Burgess reagent) as the dehydrating agent.
TL;DR: In this paper, a frequency-doubled Nd:YAG laser at 532 nm was used for optical limiting and thermal lensing studies in C70-toluene solutions.
Abstract: Optical limiting and thermal lensing studies are carried out in C70–toluene solutions. The measurements are performed using 9-ns pulses generated from a frequency-doubled Nd:YAG laser at 532 nm. Optical limiting studies in fullerene molecules lead to the conclusion that reverse saturable absorption is the major mechanism for limiting. Analysis of thermal lensing measurements showed a quadratic dependence of thermal lens signal on incident laser energy, which also supports the view that optical limiting in C70 arises due to sequential two-photon absorption via excited triplet state (reverse saturable absorption).
TL;DR: In this paper, the authors compared the performance of methanol and DMC as an alkylating agent for N-monomethylation of aniline using Zn-Co ferrites.
Abstract: The catalyst compositions of the Zn1 x Cox Fe2O4 (xD 0, 0.2, 0.5, 0.8 and 1.0) spiel series possessing ‘ x’ values, x0.5, are unique for selective N-monomethylation of aniline using methanol as the alkylating agent. Since dimethyl carbonate (DMC) is another potential non-toxic alkylating agent, alkylation of aniline was investigated over various Zn‐Co ferrites using DMC as the alkylating agent. The merits and demerits of the two alkylating agents are compared. Catalytic activity followed a similar trend with respect to the composition of the ferrospinel systems. DMC is active at comparatively low temperature, where methanol shows only mild activity. However, on the selectivity basis, DMC as an alkylating agent could not compete with methanol, since the former gave appreciable amounts of N,N-dimethylaniline (NNDMA) even at low temperature where methanol gave nearly 99% N-methylaniline (NMA) selectivity. As in the case of methanol, DMC also did not give any C-alkylated products. © 2000 Elsevier Science B.V. All rights reserved.
TL;DR: In this paper, the authors used the hypocentral data of shallow earthquakes (h≤70 km) for the period 1897-1995, a large number of focal mechanism solutions and other geophysical data in correlation with major morphotectonic features in the Burmese arc and the adjoining areas.
TL;DR: It is shown that coupled higher-order nonlinear Schrodinger (CHNLS) equations admit the Painleve property and Hirota bilinearizing the CHNLS equations for the integrable cases is succeeded.
Abstract: Using Painleve singularity structure analysis, we show that coupled higher-order nonlinear Schrodinger (CHNLS) equations admit the Painleve property. Using the results of the Painleve analysis, we succeed in Hirota bilinearizing the CHNLS equations for the integrable cases. Solving the Hirota bilinear equations, one soliton and two soliton solutions are explicitly obtained. Lax pairs are explicitly constructed.
TL;DR: In this article, the effect of stepwise increase in the coupling strength (C) on the synchronisation of the chaotic outputs of two directly modulated semiconductor lasers, using bi-directional coupling, is studied, with the help of parameter space plots, synchronisation error plots, phase diagrams and time series outputs.
01 Jul 2000
TL;DR: In this article, the correlation between long-term mean heat content and dynamic height was used to estimate the dynamic heights from the temperature profiles of the Indian Ocean, except the northern part of the Arabian Sea and the Indonesian throughflow region.
Abstract: The correlation between long-term mean heat content and dynamic height is used to estimate the dynamic heights from the temperature profiles of the Indian Ocean. Significant correlation is obtained for the whole Indian Ocean, except the northern part of the Arabian Sea and the Indonesian throughflow region. From the estimated dynamic heights, bimonthly means were computed, and maps were prepared to infer the circulation. The North Equatorial Current, South Equatorial Current, Equatorial Counter Current and the South Indian Ocean Current are clearly distinguished in the maps. Strong Indonesian throughflow is evident during July–August. The seasonal change of the Leeuwin Current off western Australia can also be observed in the dynamic height distribution. The equatorial Kelvin wave and the reflected Rossby waves at low latitudes can be identified in the time-latitude section of the steric height. An annual signal of a Rossby wave is obtained along 12°S.
TL;DR: In this article, the authors reported the alkylation of aniline with dimethyl carbonate (DMC) over Zn1−xCoxFe2O4 (x=0, 0.2, 0., 5, 0, 8 and 1.0) type systems prepared via coprecipitation route.
Abstract: The alkylation of aniline with dimethyl carbonate (DMC) is reported over Zn1−xCoxFe2O4 (x=0, 0.2, 0.5, 0.8 and 1.0) type systems prepared via. coprecipitation route. The influence of surface acid–base properties, cation distribution in the spinel lattice and various reaction parameters are discussed. It was observed that systems possessing low x values are highly selective and active for N-alkylation leading to N-methyl aniline as the major product. Since the authors have already reported the alkylation reaction using methanol as the alkylating agent over the same ferrospinel systems, in some cases both data are compared to highlight the merits and demerits of the choice of the two alkylating agents. DMC is acting as a better alkylating agent at comparatively low temperature, where methanol shows only mild activity. However, on the selectivity basis DMC as an alkylating agent could not compete with methanol, since the former executed appreciable amount of N,N-dimethylaniline (NNDMA) even at low temperature where methanol gave nearly 99% NMA selectivity. Cation distribution in the spinel lattice influences its acido-basic properties, and hence, these factors have been considered as helpful to evaluate the activity and stability of the systems.
TL;DR: In this article, three xanthate accelerators were used for room temperature curing of rubber compounds with different types of xanthates, from 30 to 150°C, and properties such as tensile strength, tear strength, crosslink density, elongation at break, and modulus at 300% elongation were evaluated.
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 tempera- tures 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. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1769-1775, 2000
TL;DR: A detailed ultrasonic study of the elastic properties of glycine phosphite single crystals has been carried out at room temperature as well as across the ferroelectric phase-transition temperature.
Abstract: A detailed ultrasonic study of the elastic properties of glycine phosphite single crystals has been carried out at room temperature as well as across the ferroelectric phase-transition temperature All 13 elastic stiffness moduli of this monoclinic crystal at room temperature have been determined by measuring the velocities of ultrasonic waves of different polarizations, propagating along different symmetry directions using the pulse echo overlap technique The anisotropy in elastic wave propagation is established employing polar plots of the phase velocity surfaces in the ab, ac, and bc planes Variation of selected mode velocities with temperature establishes the reported ferroelectric phase transition in this crystal at 224 K
TL;DR: In this article, the authors measured the longitudinal and shear elastic moduli of a glass with the general formula (Bi2O3)1 - x(CuO)x using ultrasonic wave velocities between 300 and 470 K, which are well below the glass transition temperature of this system.
Abstract: Oxide glasses with the general formula (Bi2O3)1 - x(CuO)x have been prepared by quick quenching technique. Their longitudinal and shear elastic moduli have been determined by measuring the corresponding ultrasonic wave velocities between 300 and 470 K, which are well below the glass transition temperature of this system. Temperature variation of ultrasonic velocity and attenuation exhibit anomalies around 435 K in glasses with x ≥ 0.3. A nonlinear behaviour is also reflected in the CuO concentration dependent dielectric constant curve around x = 0.3. These anomalies are interpreted in terms of a structural softening (or transformation) taking place in samples having CuO concentration above the critical value. The high dielectric constant of these glasses show very little increase with increase of temperature. Anomalies are also found in the temperature dependence of dielectric constant around 435 K. This behaviour is again considered to be associated with the softening of the glass network.
TL;DR: In this article, the authors used Thermally Stimulated Current (TSC) measurements in order to get a clear picture of the trap levels present in thin films and discussed a possible explanation for this phenomenon.
Abstract: CuInSe2 thin films, prepared using the Chemical Bath Deposition (CBD) technique, were analysed using Thermally Stimulated Current (TSC) measurements in order to get a clear picture of the different trap levels present in it. As-prepared samples showed two trap levels: the prominent one was due to the presence of a Se vacancy, while the weak one was due to the presence of a Cu vacancy. After annealing in air, the Se vacancy disappeared and a new level appeared which is suspected to be due to adsorbed oxygen. But annealing in air does not affect the Cu vacancy. On the other hand, annealing in vacuum does not affect Se vacancy, but the presence of an Fe impurity was detected in this case. A possible explanation for this phenomenon is also discussed. The dark conductivity measurements were also conducted on as-prepared as well as annealed CuInSe2 samples. These results are found to be in good agreement with the results obtained from TSC measurements.
01 Dec 2000
TL;DR: A new classifier based on Bayes' principle that assumes the clustering of attribute values while boosting the attribute differences is presented and is found to have optimal generalization ability on all the datasets.
Abstract: A new classifier based on Bayes' principle that assumes the clustering of attribute values while boosting the attribute differences is presented. The method considers the error produced by each example in the training set in turn and updates the connection weights associated to the probability P(U_{m}\mid C_{k}) of each attribute of that example. In this process the probability density of identical attribute values flattens out and the differences get boosted up. Using four popular datasets from the UCI repository, some of the characteristic features of the network are illustrated. The network is found to have optimal generalization ability on all the datasets. For a given topology, the network converges to the same classification accuracy and the training time as compared to other networks is less. One of the examples indicates the possibility that the optimization of the network may be done in parallel.
TL;DR: In this paper, a dual frequency dual-polarized square microstrip patch antenna with a slot is presented, which offers tunability of the frequency ratio between the two frequencies by adjusting the slot dimensions.
Abstract: A novel dual frequency dual-polarized square microstrip patchantenna embedded with a slot is presented. The proposed antenna offers tunability of the frequency ratio between the two frequencies by adjusting theslot dimensions. This configuration also provides a size reductionup to -51 and 35% for the two modes as compared to a square microstrip patch antenna. ® 2000 John Wiley & Sons, Inc. Microwave Opt Technol Lett 25: 395-397, 2000.
TL;DR: NiO-Al2O3 catalyst prepared by calcining a Ni-Al hydrotalcite precursor efficiently reduces nitro-arenes and carbonyl compounds in presence of propan-2-ol and KOH.