S. Chakraborty

Jadavpur University, Kolkata, Bengal, India

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Publications (35)54.09 Total impact

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    F.rahaman, S.chakraborty, J.bera
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    ABSTRACT: Exact solutions are obtained for an inhomogeneous cosmological model in normal gauge for Lyra's geometry. Some properties of the model have also been discussed.
    International Journal of Modern Physics D 01/2012; 11(09). DOI:10.1142/S0218271802001937 · 1.42 Impact Factor
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    F.rahaman, S.chakraborty, M.kalam
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    ABSTRACT: Using a 'Cut and Paste' technique, we develop a thin-shell wormhole in the heterotic string theory. We determine the surface stresses, which are localized in the shell, by using Darmois–Israel formalism. The linearized stability of this thin wormhole is also analyzed.
    International Journal of Modern Physics D 01/2012; 16(10). DOI:10.1142/S0218271807010924 · 1.42 Impact Factor
  • Talanta 10/2009; 79(5):1490-1490. DOI:10.1016/j.talanta.2009.04.055 · 3.51 Impact Factor
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    ABSTRACT: In this article, we describe a method used to prepare an in situ sodium-activated, organomodified bentonite clay/styrene–butadiene rubber nanocomposite master batch via a latex blending technique. The clay master batch was used for compound formulation. Octadecyl amine was used as an organic intercalate. The clay was purchased from local suppliers and was very cheap. Sodium chloride was used for in situ activation of the clay. The wide-angle X-ray diffraction data indicated that the in situ sodium activation helped to increase the intergallery distance from 1.28 to 1.88 nm. A transmission electron micrograph indicated intercalation and partial exfoliation. The thermal properties were relatively better in the case of the sodium-activated, organomodified bentonite-clay-containing compound. A substantial improvement in physical properties such as the modulus, tensile strength, tear strength, and elongation at break was observed in the case of the in situ sodium-activated compound. A cation-exchange capacity equivalent (of the clay) of 1.5 times the octadecyl amine was the optimum dose for the modification. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
    Journal of Applied Polymer Science 07/2009; 113(2):1316 - 1329. DOI:10.1002/app.30146 · 1.64 Impact Factor
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    ABSTRACT: In this article, a special static spherically symmetric perfect fluid solution of Einstein's equations is provided. Though pressure and density both diverge at the origin, their ratio remains constant. The solution presented here fails to give positive pressure but nevertheless, it satisfies all energy conditions. In this new spacetime geometry, the metric becomes singular at some finite value of radial coordinate although, by using isotropic coordinates, this singularity could be avoided, as has been shown here. Some characteristics of this solution are also discussed.
  • S. Chakraborty, R. Pyare
    Advances in Applied Ceramics 08/2008; 107(4):227-231. DOI:10.1179/174367508X289424 · 1.11 Impact Factor
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    ABSTRACT: According to the KEMI report, products with polycyclic aromatic compounds, PCA, levels exceeding 3% by weight must be labelled. The report pointed out that worn tyre tread material was being spread on the roadsides, introducing high amounts of PCA into the environment. PCA is having toxic effects on aquatic organisms. Polyaromatic-hydrocarbon-rich extender oils are to be banned by December 2009, which gives rise to challenges for the oil and rubber industries. In the present work, 10 types of naturally occurring oils and six types of petroleum-based oils were characterised in natural-rubber-based truck tyre tread cap compound. Compounds made with some of the naturally occurring oils showed better mechanical and dynamic mechanical properties.
    Polymer Testing 05/2008; 27(3-27):277-283. DOI:10.1016/j.polymertesting.2007.11.004 · 1.82 Impact Factor
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    ABSTRACT: Considering the short-term exposure limit of SO2 to be 5 ppm, we first time report that semiconductor sensors based on vanadium doped SnO2 can be used for SO2 leak detection because of their good sensitivity towards SO2 at concentrations down to 5 ppm. Such sensors are quite selective in presence of other gases like carbon monoxide, methane and butane. The high sensitivity of vanadium doped tin dioxide towards SO2 may be understood by considering the oxidation of sulfur dioxide to sulfur trioxide on SnO2 surface through redox cycles of vanadium-sulfur-oxygen adsorbed species.
    Talanta 05/2008; 75(2):385-9. DOI:10.1016/j.talanta.2007.11.010 · 3.51 Impact Factor
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    ABSTRACT: Nanocrystalline gamma iron oxide (γ-Fe2O3) has been synthesized at room temperature through sonication-assisted precipitation technique. The key in obtaining γ-Fe2O3 at room temperature lies in exploiting high-power ultrasound (600W). The gas-sensing properties to n-butane of pure γ-Fe2O3 were investigated by studying the electrical properties of the sensor elements fabricated from the synthesized powder. The maximum response (∼90%) of the sensor to 1000ppm n-butane at 300°C can be explained on the basis of catalytic activity of the nanocrystallites. The response and recovery time of the sensor to 1000ppm n-butane were less than 12s and 120s, respectively.
    Sensors and Actuators B Chemical 03/2008; 130(2):882-888. DOI:10.1016/j.snb.2007.10.057 · 3.84 Impact Factor
  • S. Chakraborty, R. Pyare
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    ABSTRACT: Crystallisation behaviour of Li2O-Al2O3-SiO2 system (LAS) glass ceramics containing TiO2 doping and non-doping is investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The introduction of TiO2 decreases the crystallising peak temperature T-p and the crystallising activation energy E and improves the crystallisation stage to obtain fine crystal with a size of similar to 100 nm. A controlled surface reaction of the ceramic is an important factor governing the bioinert and biodegradation nature of the implanted ceramic. The addition of TiO2 improves the chemical durability of the glass ceramic, by reducing the number of non-bridging oxygens, suppressing the tendency for amorphous phase separation and provides a more dense and stable structure. This results in a decrease in the release rate of Li+, Al3+ and Si4+ ions in a simulated body fluid.
    Advances in Applied Ceramics 03/2008; 107(2):70-75. DOI:10.1179/174367607X228025 · 1.11 Impact Factor
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    ABSTRACT: Along with high sensitivity towards detecting gases, the response and recovery times of semiconductor gas sensors are of paramount importance for practical applications. In most of the cases, the recovery time is larger than the response time. Incidentally, water vapour present in the ambience is chemisorbed on the semiconductor oxide surface and the water molecules dissociate into hydroxyl species, which act as electron donors. In the present study on tin dioxide-based methane sensor, we find that if the interference of adsorbed moisture can be reduced by surface treatment with a dilute thiourea solution, the recovery time and stability of the sensor improve, which make them suitable for practical applications.
    Sensors and Actuators B Chemical 11/2007; 127(2):554-558. DOI:10.1016/j.snb.2007.05.005 · 3.84 Impact Factor
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    ABSTRACT: The invention of Nylon-6/clay nanocomposites by the Toyota Research Group of Japan heralded a new chapter in the field of polymer composites. This article highlights the work done in the field of rubber/clay nanocomposites. The preparations of rubber/clay nanocomposites by solution blending, latex compounding, and melt intercalation are covered and a thorough discussion of the mechanical properties of the various rubber/clay nanocomposite systems is presented. Other properties such as barrier, dynamic mechanical behavior, and thermal properties are also discussed. Finally, the future trends in the rubber/clay nanocomposites are mentioned. POLYM. ENG. SCI., 47:1956–1974, 2007. © 2007 Society of Plastics Engineers
    Polymer Engineering and Science 11/2007; 47(11):1956 - 1974. DOI:10.1002/pen.20921 · 1.44 Impact Factor
  • S. Chakraborty, R. K. Chaturvedi, R. Pyare
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    ABSTRACT: Glasses with compositions of (100?X?Y)Li2O.Al2O3.4SiO2+XB2O3+YP2O5 where X=0–2.5 and Y=0–10 (wt-%) were melted in a platinum crucible at 1500°C with air as the furnace atmosphere. The green compact pellets were prepared and fired at 500°C. The samples were sintered in air atmosphere at selected temperatures in the range of 750–900°C for up to 20 h. It has been found that the addition of B2O3 and P2O5 has a remarkable effect on the amount of ? spodumene (?-S), relative to high quartz solid solution (h-QSS). The glass ceramics that contain appropriate amounts of B2O3 and P2O5 promise good sinterability at temperature as low as 850°C. There were two major types of phase transformation in the present investigation: crystallisation of the present glass to a metastable h-QSS and subsequent transformation from h-QSS to a stable ?-S. In vitro test revealed that the spodumene glass ceramic is much more durable in human body fluid. It is further observed that the addition of B2O3 and P2O5 enhanced the chemical durability of glass ceramics.
    Advances in Applied Ceramics 09/2007; 106(5):216-221. DOI:10.1179/174367607X159356 · 1.11 Impact Factor
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    F. Rahaman, M. Kalam, B. C. Bhui, S. Chakraborty
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    ABSTRACT: In this article, we have found a series solution of 3D Einstein equations describing a wormhole for an inhomogeneous distribution of phantom energy. Here, we assume equation of state is linear but highly anistropic.
    Physica Scripta 06/2007; 76(1). DOI:10.1088/0031-8949/76/1/010 · 1.30 Impact Factor
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    F. Rahaman, M. Kalam, S. Chakraborty
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    ABSTRACT: It has been recently shown that Hoyle-Narlikar's C-field theory admits wormhole geometry. We derive the deflection angle of light rays caused by C-field wormhole in the strong field limit approach of gravitational lensing theory. The linearized stability of C-field wormhole under spherically symmetric perturbations about static equilibrium is also explored.
    Chinese Journal of Physics- Taipei- 06/2007; · 0.43 Impact Factor
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    ABSTRACT: Polyaromatic hydrocarbon-rich extender oils are to be banned by December 2009 which gives rise to challenges for the oil and rubber industries. In the present work, 10 types of naturally occurring oils and six types of petroleum-based oils were characterized for chemical and physical properties. The effect of these process oils in natural rubber-based truck-tyre tread cap compound was also studied. Some of the naturally occurring oils showed better processing properties, polymer–filler interaction and dispersion properties.
    Polymer Testing 06/2007; 26(4):489-500. DOI:10.1016/j.polymertesting.2007.01.007 · 1.82 Impact Factor
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    F. Rahaman, M. Kalam, S. Chakraborty
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    ABSTRACT: We propose wormholes solutions by assuming space dependent equation of state parameter. Our models show that the existence of wormholes is supported by arbitrary small quantities of averaged null energy condition (ANEC) violating phantom energy characterized by variable equation state parameter.
    Acta Physica Polonica Series B 02/2007; · 1.00 Impact Factor
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    ABSTRACT: Infrared spectroscopy can be used efficiently by polymer and rubber technologists for identification of polymer, polymer–blend ratio calculation, raw material evaluation, study of reaction mechanism, microstructure determination, etc. The present article represents a method to characterize nitrile rubber by Fourier-transformed infrared spectrophotometry (FTIR). The absorbance ratio of specific peaks of different grades of nitrile rubber was correlated with the acrylonitrile content measured by the Kjeldhal method. The acrylonitrile content of unknown acrylonitrile butadiene rubber (nitrile rubber, NBR) was calculated from a calibration graph.
    Polymer Testing 02/2007; 26(1-26):38-41. DOI:10.1016/j.polymertesting.2006.08.004 · 1.82 Impact Factor
  • S. Chakraborty, A. Sen, H. S. Maiti
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    ABSTRACT: Thick film methane sensors have been fabricated from nanosized tin dioxide powder containing antimony oxide and palladium. The powder has been prepared by sonication-assisted simultaneous precipitation and the sensors made with this powder showed optimum resistance for device applications and good sensitivity towards methane. This contrasts with the thick film sensors prepared with the powder synthesized without sonication, which showed very high resistance at the operating temperature. The complex plane impedance spectroscopy of the sensors (both in air and in the presence of gas) can be a good indicator of the sensor quality. It has been observed that the nature of the complex plane impedance plot of the sensors fabricated by using powders synthesized through sonication-assisted simultaneous precipitation matches well with that of high-quality imported Figaro (Japan) sensors.
    Sensors and Actuators B Chemical 12/2006; 119(2):431-434. DOI:10.1016/j.snb.2005.12.045 · 3.84 Impact Factor
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    ABSTRACT: In the present study, coagulated styrene-vinylpyridine-butadiene ter-polymer latex (VP latex) is used as a secondary accelerator to increase the cure rate in the sulfonamide—sulfur curing system in natural as well as synthetic rubber-based compounds. The activation energy is observed to be lower when coagulated VP latex is used as a secondary accelerator. All other physical properties are observed to be comparable. It is found that a small amount of coagulated VP ter-polymer is sufficient to increase the reaction rate. However, it is also found that coagulated VP latex alone is not a satisfactory accelerator.
    Journal of Elastomers and Plastics 07/2006; 38(3):249-260. DOI:10.1177/0095244306064236 · 0.71 Impact Factor

Publication Stats

434 Citations
54.09 Total Impact Points

Institutions

  • 2003–2012
    • Jadavpur University
      • Department of Mathematics
      Kolkata, Bengal, India
  • 2007–2008
    • Banaras Hindu University
      • Department of Ceramic Engineering
      Vārānasi, Uttar Pradesh, India
  • 2006–2008
    • Central Glass and Ceramics Research Institute
      • Nanostructured Materials Division (CGCRI)
      Kolkata, Bengal, India
  • 2006–2007
    • Meghnad Saha Institute of Technology
      Kolkata, Bengal, India