Showing papers by "Jadavpur University published in 2004"

Role of modified Chaplygin gas in accelerated universe

Abstract: In this paper, we have considered a model of modified Chaplygin gas and its role in the accelerating phase of the universe We have assumed that the equation of state of this modified model is valid from the radiation era to the ΛCDM model We have used recently developed statefinder parameters in characterizing different phases of the universe diagrammatically

Groundwater arsenic contamination and its health effects in the Ganga-Meghna-Brahmaputra plain.

Abstract: School of Environmental Studies, Jadavpur University, Kolkata, India Department of Neurology, Medical College, Kolkata, India Department of Obstetrics and Gynaecology, Institute of Post Graduate Medical Education and Research, S.S.K.M. Hospital, Kolkata, India Retired Professor of Dermatology, School of Tropical Medicine, Kolkata Department of Dermatology, Institute of Post Graduate Medical Education and Research, S.S.K.M. Hospital, Kolkata, India Dhaka Community Hospital, Dhaka, Bangladesh

Advancement in electrochemical micro-machining

Abstract: Electrochemical micro-machining (EMM) appears to be very promising as a future micro-machining technique, since in many areas of applications it offers several advantages, which include higher machining rate, better precision and control, and a wide range of materials that can be machined. In this paper, a review is presented on current research, development and industrial practice in micro-ECM. This paper highlights the influence of various predominant factors of EMM such as controlled material removal, machining accuracy, power supply, design and development of microtool, role of inter-electrode gap and electrolyte, etc. EMM can be effectively used for high precision machining operations, that is, for accuracies of the order of ±1 μm on 50 μm. Some industrial applications of EMM have also been reported. Further research into EMM will open up many challenging opportunities of improvement towards greater machining accuracy, new materials machining and generation of complex shapes for effective utilization of ECM in the micro-machining domain.

Formulation design of self-microemulsifying drug delivery systems for improved oral bioavailability of celecoxib.

Abstract: Celecoxib is a hydrophobic and highly permeable drug belonging to class II of biopharmaceutics classification system. Low aqueous solubility of celecoxib leads to high variability in absorption after oral administration. Cohesiveness, low bulk density and compressibility, and poor flow properties of celecoxib impart complications in it's processing into solid dosage forms. To improve the solubility and bioavailability and to get faster onset of action of celecoxib, the self-microemulsifying drug delivery system (SMEDDS) was developed. Composition of SMEDDS was optimized using simplex lattice mixture design. Dissolution efficiency, t85%, absorbance of diluted SMEDDS formulation and solubility of celecoxib in diluted formulation were chosen as response variables. The SMEDDS formulation optimized via mixture design consisted of 49.5% PEG-8 caprylic/capric glycerides, 40.5% mixture of Tween20 and Propylene glycol monocaprylic ester (3 : 1) and 10% celecoxib, which showed significantly higher rate and extent of absorption than conventional capsule. The relative bioavailability of the SMEDDS formulation to the conventional capsule was 132%. The present study demonstrated the suitability of mixture design to optimize the compositions for SMEDDS. The developed SMEDDS formulations have the potential to minimize the variability in absorption and to provide rapid onset of action of celecoxib.

Inverted metamorphic sequence in the Sikkim Himalayas: crystallization history, P–T gradient and implications

Abstract: The metapelitic rocks of the Sikkim Himalayas show an inverted metamorphic sequence (IMS) of the complete Barrovian zones from chlorite to sillimanite + K-feldspar, with the higher grade rocks appearing at progressively higher structural levels. Within the IMS, four groups of major planar structures, S1 ,S 2 and S3 were recognised. The S2 structures are pervasive throughout the Barrovian sequence, and are sub-parallel to the metamorphic isograds. The mineral growth in all zones is dominantly syn-S2. The disposition of the metamorphic zones and structural features show that the zones were folded as a northerly plunging antiform. Significant bulk compositional variation, with consequent changes of mineralogy, occurs even at the scale of a thin section in some garnet zone rocks. The results of detailed petrographic and thermobarometric studies of the metapelites along a roughly E-W transect show progressive increase of both pressure and temperature with increasing structural levels in the entire IMS. This is contrary to all models that call for thermal inversion as a possible reason for the origin of the IMS. Also, the observation of the temporal relation between crystallization and S2 structures is problematic for models of post-/late-metamorphic tectonic inversion by recumbent folding or thrusting. A successful model of the IMS should explain the petrological coherence of the Barrovian zones and the close relationship of crystallization in each zone with S2 planar structures along with the observed trend(s) of P-T variation in Sikkim and in other sections. A discussion is presented of some of the available models that, with some modifications, seem to be capable of explaining these observations.

Antitumor activity and antioxidant role of Bauhinia racemosa against Ehrlich ascites carcinoma in Swiss albino mice [corrected].

Abstract: AIM: To study the antitumor effect and antioxidant role of Bauhinia racemosa. METHODS: Antitumor activity and antioxidant status of methanol extract (50, 100, and 200 mg/kg) of Bauhinia racemosa stem bark was evaluated against Ehrlich ascites carcinoma (EAC) tumor in mice. Acute and short-term toxicity studies were performed initially in order to ascertain the safety of methanol extract of Bauhinia racemosa (MEBR). After 24 h of tumor inoculation, the extract was administered daily for 14 d. After administration of the last dose followed by 18 h fasting, mice were then sacrificed for observation of antitumor activity. The effect of MEBR on the growth of transplantable murine tumor, life span of EAC bearing hosts and simultaneous alterations in the hematological profile and liver biochemical parameters (lipid peroxidation, antioxidant enzymes) were estimated. RESULTS: The MEBR showed decrease in tumor volume, packed cell volume and viable cell count, and increased the nonviable cell count and mean survival time thereby increasing life span of EAC tumor bearing mice. Hematological profile reverted to more or less normal levels in extract treated mice. Treatment with MEBR decreased the levels of lipid peroxidation and increased the levels of glutathione, superoxide dismutase and catalase. CONCLUSION: The methanol extract of Bauhinia racemosa stem bark exhibited antitumor effect by modulating lipid peroxidation and augmenting antioxidant defense system in EAC bearing mice.

1α, 25-dihydroxyvitamin D3 prevents DNA damage and restores antioxidant enzymes in rat hepatocarcinogenesis induced by diethylnitrosamine and promoted by phenobarbital

Abstract: AIM: To investigate the chemopreventive effects of 1α, 25-dihydroxyvitamin D3 in diethylnitrosamine induced, phenobarbital promoted rat hepatocarcinogenesis. METHODS: The rats were randomly divided into 6 different groups (A-F). Groups A, C and E rats received a single intraperitoneal (i.p) injection of diethylnitrosamine (DEN) at a dose of 200 mg/kg body mass in 9 g/L NaCl solution at 4 wk of age, while group B served as normal vehicle control received normal saline once. After a brief recovery of 2 wk, all the DEN treated rats were given phenobarbital (PB) at 0.5 g/L daily in the basal diet till wk 20. Group A was DEN control. Treatment of 1α, 25-(OH)2D3 in group C was started 4 wk prior to DEN injection and continued thereafter till wk 20 at a dose of 0.3 μg/100 μL propylene glycol per one single dose (os) twice a week. Group E received the treatment of 1α, 25-(OH)2D3 at the same dose mentioned as above for 15 wk. The rats in group D and F received 1α, 25-(OH)2D3 alone as in group C without DEN injection. RESULTS: The comet assay showed statistically higher mean values for length to width ratios (L: W) of DNA mass and tailed cells (P < 0.01; P < 0.01 respectively) in DEN treated rats as compared to their normal controls. Continuous supplementation of 1α, 25-dihydroxyvitaminD3 showed a significant (P < 0.01) decrease in L:W ratio of DNA mass tailed cells. Furthermore, 1α, 25-(OH)2D3 supplementations elevated the super oxide dismutase (SOD) activity, hepatic malondialdehyde (MDA) level, reduced glutathione (GSH) and glutathione S-transferase (GST) activity (P < 0.01, P < 0.05, P < 0.05 and P < 0.05 respectively). As an endpoint marker histological changes were observed to establish the chemopreventive effects of 1α, 25-dihydroxyvitaminD3. CONCLUSION: Supplementations of 1α, 25-(OH)2D3 has a marked protection against hepatic nodulogenesis, antioxidant enzymes and DNA damages in DEN induced rat hepatocarcinogenesis promoted by phenobarbital.

Oxidative Stress-Induced Ischemic Heart Disease: Protection by Antioxidants

Abstract: Heart disease is one of the major health problems of advanced as well as developing countries of the world. Extensive research through the last decade has shown beyond doubt that free radicals, particularly, reactive oxygen species play a cardinal role in the pathogenesis of oxidative myocardial damage with consequential cardiac malfunction. This review presents a comprehensive account of the present day knowledge regarding the oxygen free radicals involved in the genesis of ischemic heart disease, the mechanism(s) of oxidative myocardial damage and the endogenous as well as exogenous antioxidant defense systems. Furthermore, the role of ischemic pre-conditioning, some antioxidants and the ability of some cardioprotective drugs in providing protection against the ischemic myocardial damage are also discussed. The text of the article comes to an end with a commentary on the future research perspective in the concerned area, which throws a light on the development of combinatorial therapeutics in the treatment of ischemic myocardial disease.

Mode of Action of Endotoxin: Role of Free Radicals and Antioxidants

Abstract: The pathogenetic sequence of reactions mediated by endotoxin (LPS) leading to the production of sepsis involves the oxygen radicals or reactive oxygen species, which has been evaluated in the present review. Among reactive oxygen species hydroxyl radical either singly or in combination with peroxynitrite, produces tissue damage often observed during septic injury. Inactivation of these damaging radicals by antioxidants or nitric oxide inhibitor(s) may be helpful for protecting sepsis mediated derangements but the application of these agents as drugs in humans has not been fully successful. Transcription factor NF-kappa B is reported to be the oxygen sensor in LPS induced endotoxemia. Polyphenols, especially the catechin group of compounds, are important therapeutic agents, which may be used for the treatment of endotoxin mediated sepsis.

End-to-end single cyanato and thiocyanato bridged Cu(II) polymers with a new tridentate Schiff base ligand: Crystal structure and magnetic properties

Abstract: A new tridentate Schiff base ligand HL (L = C14H19N2O), derived from the condensation of benzoylacetone and 2-dimethylaminoethylamine in a 1 ∶ 1 ratio, reacts with copper(II) acetate and cyanate, thiocyanate or azide, to give rise to several end-to-end polymeric complexes of formulae [CuL(µ1,3-NCO)]n1, [CuL(µ1,3-NCS)]n2 and the complex 3 has two crystallographically independent units of formula [CuL(N3)] in the asymmetric unit cell. Complex 3 exists in dimeric form rather than as a polymeric chain. Compound 1 is the first report of a singly end-to-end cyanate bridged polymeric chain of Cu(II) with a Schiff base as a co-ligand. There are many examples of double NCS bridged polymeric chains, but fewer singly bridged ones such as compound 2. We have characterized these complexes by analytical, spectroscopic, structural and variable temperature magnetic susceptibility measurements. The coordination geometry around the Cu(II) centers is distorted square pyramidal for 1 and 2 and square planar for complex 3. The magnetic susceptibility data show slight antiferromagnetic coupling for the polymers having J values −0.19 and −0.57 cm−1 for complexes 1 and 2 respectively. The low values of J are consistent with the equatorial–axial disposition of the bridges in the polymers.

In(OTf)3 catalysed simple one-pot synthesis of α-amino phosphonates

Abstract: A new efficient one-pot synthesis of α-amino phosphonates derived from nitro substituted anilines, aldehydes and diethyl phosphite has been carried out by employing 5 mol% of In(OTf) 3 . The method is equally effective for the generation of α-amino phosphonates from various carbonyl compounds and other amines.

In(OTf)3-catalysed one-pot synthesis of 3,4-dihydropyrimidin-2(lH)-ones

Abstract: A variety of aldehydes reacted in one-pot with ethyl or methyl acetoacetate and urea or thiourea in the presence of 2 mol% In(OTf) 3 furnishing the corresponding dihydropyrimidinones or their thio analogues in very good to excellent yields.

Contradictions of Democracy in a Workers’ Cooperative:

Abstract: Organizational democracy has become a key issue in current change-management programmes, such as restructuring, total quality management and Enterprise Resource Planning, and there has been a persistent quest for a post-Fordist model in recent times. The article emphasizes the need to study democratic processes per se, given that democracy faces significant odds vis-a-vis the larger context, even in those organizations that have been expressly initiated for democratic functioning. The contradictions with the context inevitably manifest themselves inside the organization as well. The present study makes a case for understanding organizational democracy as an evolving reality, based on participant observation of democratic functioning within a workers’ cooperative over seven years.

Virulence Characteristics and Molecular Epidemiology of Enteroaggregative Escherichia coli Isolates from Hospitalized Diarrheal Patients in Kolkata, India

Abstract: Enteroaggregative Escherichia coli (EAEC) is an important diarrheal enteropathogen defined by aggregative adherence to cultured epithelial cells. We have detected EAEC from 121 (6.6%) of 1,826 hospitalized patients admitted with diarrhea to the Infectious Diseases Hospital in Kolkata, India. Watery diarrhea was recorded significantly (P = 0.0142) more often in children. The majority of the EAEC isolates were not serotypeable (62%) and showed resistance to five or more antibiotics (76%). We studied different virulence genes and the molecular epidemiology of 121 EAEC isolates recovered from diarrheal patients. A PCR assay for detection of virulence genes, an assay for determination of clump formation in liquid culture, and a HeLa cell adherence assay were carried out to characterize the EAEC isolates. Investigations were also conducted to correlate the virulence gene profiles with diarrheal symptoms and molecular epidemiology by pulsed-field gel electrophoresis (PFGE). Two or more virulence genes were detected in 109 (90.1%) EAEC isolates. In the cluster analysis, some isolates with specific gene profiles and phenotypes formed a group or subcluster. This study highlights the comparative distributions of three fimbrial adhesins and other virulence genes among EAEC isolates. The diverse virulence gene and PFGE profiles, along with the existence of diverse serotypes and antibiograms, suggests that the EAEC isolates are genetically heterogeneous in Kolkata.