Papers by purushottam jha
The objective of the present study was to inhibit experimental autoimmune anterior uveitis (EAAU)... more The objective of the present study was to inhibit experimental autoimmune anterior uveitis (EAAU) by establishing antigen specific immune tolerance in animals pre-sensitized with melanin associated antigen (MAA). Intravenous administration of MAA on day 6, 7, 8 and 9 post-immunization induced tolerance and inhibited EAAU in all Lewis rats. Number of cells (total T cells, CD4+ T cells and CD8+ T cells) undergoing apoptosis dramatically increased in the popliteal lymph nodes (LNs) of the tolerized animals compared to non-tolerized animals. Additionally, FasL, TNFR1 and caspase-8 were upregulated in tolerized rats. Proliferation of total lymphocytes, CD4+T cells and CD8+ T cells (harvested from the popliteal LNs) in response to antigenic stimulation was drastically reduced in the state of tolerance compared to the cells from non-tolerized animals. Level of IFN-γ and IL-2 decreased while TGF-β2 was elevated in the state of tolerance. Furthermore, the number of CD4+CD25+FoxP3+ Tregs incr...
In this paper we introduce and study a new class of generalized closed sets called, Dβ-closed set... more In this paper we introduce and study a new class of generalized closed sets called, Dβ-closed sets, which are the generalization of Dα-closed sets defined in O.R. Sayed, A.M. Khalil, Some applications of Dα-closed sets in topological spaces, 3(2016), 26–34 [25], pre∗-closed set defined in T.Selvi, A. Punitha Dharani, Some new class of nearly closed and open sets, Asian Jour. of current engineering and maths, 5(2012), 305-307 [26] and semi∗-closed sets defined in A. Robert, S. Pious Missier, On semi∗-closed sets, Asian journal of current engineering and maths, 4(2012), 173–176 [23]. We establish the relationship of Dβ-closed sets with some already existing generalized closed sets. We define Dβ-continuous and Dβ-irresolute functions and obtain their basic properties. AMS subject classification: Primary 54A05, 54C05, 54C08; Secondary 54C10, 54D10, 54C99.
ABSTRACT We demonstrate a dye sensitized solar cell (DSSC) using a new organic dye (i.e. rhodamin... more ABSTRACT We demonstrate a dye sensitized solar cell (DSSC) using a new organic dye (i.e. rhodamine 19 perchlorate) sensitized TiO2 electrode. The power conversion efficiency of the cell was found to be 1.1% under white light illumination. The binding modes of the dye to TiO2 electrode as well as the mechanism of the cell are discussed.
RSC Advances, 2013
ABSTRACT Free standing polypyrrole-silver nanocomposite films were prepared by interfacial photop... more ABSTRACT Free standing polypyrrole-silver nanocomposite films were prepared by interfacial photopolymerization of pyrrole (in DCM) using AgNO3 (aqueous) as photosensitizer. During the photopolymerization process, film formation starts first at the DCM–water interface and later at the air–water interface. The films prepared at the air–water interface are thin (<1 μm), flexible, having a very low content of uniformly distributed metallic Ag nanoparticles and exhibiting high electrical conductivity 14.8 S cm−1. The thick films (200 μm) prepared at the DCM–water interface are porous, mechanically weak, contain a very high amount of Ag micro and nanoparticles and exhibit two orders of magnitude lower conductivity 0.1 S cm−1. High conductivity of PPy-Ag films formed at the air–water interface is attributed to controlled polymerization due to the limited availability of pyrrole and Ag+ ions at this interface.
ABSTRACT The performance of dye-sensitized solar cells is improved by simple formic acid treatmen... more ABSTRACT The performance of dye-sensitized solar cells is improved by simple formic acid treatment of TiO2 photoanodes. The treatment increases number of hydroxyl groups at TiO2 surface and thereby result in enhanced dye-loading and device efficiency. The best device showed an open circuit voltage of 0.62V, short-circuit current density 6.34mA/cm2, fill factor of 60%, and a power conversion efficiency of ~12 % under 20mW/cm2 white light illumination.
ABSTRACT Bulk heterojunction solar cells of 3×3 array have been fabricated using a blend of PCDTB... more ABSTRACT Bulk heterojunction solar cells of 3×3 array have been fabricated using a blend of PCDTBT:PCBM as active layer. Among nine devices fabricated, the best device exhibited efficiency 5% with standard deviation ~ 20% in efficiency. Thermal annealing of the devices resulted in decrease of photovoltaic properties of all devices which was attributable to the change at the active layer/cathode interface of devices as supported by electrical and spectroscopic studies.
ABSTRACT Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-... more ABSTRACT Poly[N-9'-heptadecanyl-2,7-carbazole-alt-5,5-(4',7'-di-2-thienyl-2',1',3'-benzothiadiazole)] (PCDTBT) which is known to be air stable, has been used as active layer to fabricate flexible organic field effect transistor. Poly(methyl methacrylate) has been used as gate dielectric. The mobility and on-off ratio for these devices were found to be 7×10-4cm2V-1s-1 and 1.5×102, respectively.
ABSTRACT We have improved the efficiency of the dye sensitization solar cells (DSSCs) by adopting... more ABSTRACT We have improved the efficiency of the dye sensitization solar cells (DSSCs) by adopting an innovative and simpler methodology of oxalic acid treatment of TiO2. It is observed that the efficiency of the DSSC is improved to 2.3% after treatment. The improvement has been understood in terms of reduced dark current and enhanced dye loading as supported by UV-Visible, electrical and electrochemical impedance measurements.
The Journal of Physical Chemistry C, 2013
The anchoring mechanism of N719 dye molecules on oxalic acid treated TiO 2 (OA-TiO 2) electrodes ... more The anchoring mechanism of N719 dye molecules on oxalic acid treated TiO 2 (OA-TiO 2) electrodes has been investigated using extended X-ray absorption fine structure (EXAFS) measurements, Fourier transform infrared spectroscopy (FTIR), UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS). The FTIR spectroscopy of OA-TiO 2 electrodes revealed that the oxalic acid dissociates at the TiO 2 surface and binds through bidentate chelating and/or bidentate bridging. Analyses of EXAFS, FTIR, UV-Vis and XPS measurements of N719 dye loaded onto OA-TiO 2 revealed that the binding of N719 molecules takes place via interaction between Ru atom of the dye and Oof bidentate bridged oxalate ions at TiO 2 surface. This mechanism is quite different to the binding of N719 onto untreated TiO 2 (WO-TiO 2) surface, where-COOH and SCN groups of the dye directly bind to TiO 2 surface. The analyses of UV-Vis data show that the amount of N719 dye loading is much higher onto OA-TiO 2 surface as compared to the native TiO 2 surface. In addition, the incident photon to current conversion efficiency (IPCE) measurements show that presence of oxalate ions between dye and TiO 2 surface favors efficient electron transfer, and therefore, improvement in device efficiency. The dye sensitized solar cells fabricated using N719 dye sensitized onto OA-TiO 2 showed an efficiency of ~4.6%, which is significantly higher than that based on WO-TiO 2 electrode (~3.2%).
Immunology and Cell Biology, 2010
The objective of the present study was to inhibit experimental autoimmune anterior uveitis (EAAU)... more The objective of the present study was to inhibit experimental autoimmune anterior uveitis (EAAU) by establishing antigen specific immune tolerance in animals pre-sensitized with melanin associated antigen (MAA). Intravenous administration of MAA on day 6, 7, 8 and 9 postimmunization induced tolerance and inhibited EAAU in all Lewis rats. Number of cells (total T cells, CD4 + T cells and CD8 + T cells) undergoing apoptosis dramatically increased in the popliteal lymph nodes (LNs) of the tolerized animals compared to non-tolerized animals. Additionally, FasL, TNFR1 and caspase-8 were upregulated in tolerized rats. Proliferation of total lymphocytes, CD4 + T cells and CD8+ T cells (harvested from the popliteal LNs) in response to antigenic stimulation was drastically reduced in the state of tolerance compared to the cells from nontolerized animals. Level of IFN-γ and IL-2 decreased while TGF-β2 was elevated in the state of tolerance. Furthermore, the number of CD4 + CD25 + FoxP3 + Tregs increased in the popliteal LNs of tolerized animals compared to non-tolerized animals. In conclusion, our results suggest that deletion of antigen specific T cells via apoptosis and active suppression mediated by Tregs plays an important role in the induction of antigen specific immune tolerance in animals with an established immune response against MAA.
FEBS letters, 2008
The objective of the present study was to investigate the effect of alcohol and nicotine consumpt... more The objective of the present study was to investigate the effect of alcohol and nicotine consumption on the pathogenesis of choroidal neovascularization (CNV) in rats after laser-photocoagulation. Confocal microscopic analysis demonstrated an increase in CNV complex size in rats fed with alcohol (2.3-fold), nicotine (1.9-fold), and the combination of alcohol and nicotine (2.7-fold) compared with the control groups.Immunohistochemical analysis revealed that alcohol and nicotine consumption increased MAC deposition and VEGF expression in laser spots. Expression of CD59 by RT-PCR and Western blot was drastically reduced in the animals that were fed with alcohol, nicotine and alcohol and nicotine compared to those fed with water alone and this was associated with exacerbation of CNV.
Applied Physics Letters, 2014
ABSTRACT The solution of thin graphene-sheets obtained from a simple ultrasonic exfoliation proce... more ABSTRACT The solution of thin graphene-sheets obtained from a simple ultrasonic exfoliation process was found to chemically interact with [6,6]-phenyl C71 butyric acid methyl ester (PCBM) molecules. The thinner graphene-sheets have significantly altered the positions of highest occupied molecular orbital and lowest unoccupied molecular orbital of PCBM, which is beneficial for the enhancement of the open circuit voltage of the solar cells. Flexible bulk heterojunction solar cells fabricated using poly 3-hexylthiophene (P3HT):PCBM-graphene exhibited a power conversion efficiency of 2.51%, which is a ∼2-fold increase as compared to those fabricated using P3HT:PCBM. Inclusion of graphene-sheets not only improved the open-circuit voltage but also enhanced the short-circuit current density owing to an improved electron transport.
The polycarbazole films deposited by Langmuir-Blodgett (LB) technique exhibit a decrease in resis... more The polycarbazole films deposited by Langmuir-Blodgett (LB) technique exhibit a decrease in resistance on exposure to NH 3 , which is exactly opposite to the usual response (i.e. increase in resistance) observed for p-type conducting polymers. We have investigated the mechanism of this uncharacteristic NH 3 sensing behavior of polycarbazole LB films by carrying out in situ Fourier transform infrared and ultraviolet-visible absorption spectroscopy. The results are compared with electropolymerized (EP) films. It is shown that EP film is p-doped, which gets reduced by interacting with NH 3 , and as a result, its resistance increases. On the other hand, LB film is found to be intrinsically undoped. Interaction with NH 3 makes LB film n-doped, which results in a decrease of its resistance. The n-doping of LB film has independently been confirmed by electrochemical reduction process.
ABSTRACT The performance of dye-sensitized solar cells is improved by simple formic acid treatmen... more ABSTRACT The performance of dye-sensitized solar cells is improved by simple formic acid treatment of TiO2 photoanodes. The treatment increases number of hydroxyl groups at TiO2 surface and thereby result in enhanced dye-loading and device efficiency. The best device showed an open circuit voltage of 0.62V, short-circuit current density 6.34mA/cm2, fill factor of 60%, and a power conversion efficiency of ~12 % under 20mW/cm2 white light illumination.
ABSTRACT Bulk-heterojunction Polymer solar cells (PSCs) have recently been emerged as promising c... more ABSTRACT Bulk-heterojunction Polymer solar cells (PSCs) have recently been emerged as promising candidates for harvesting solar energy on account of their unique abilities of electronic transport and absorption of light in the ultraviolet (UV)-Visible part of the solar spectrum. poly(3-hexylthiophene) is a promising candidate for PSC due to its stability and absorption in the red region. In this paper, we report polymer solar cells based on P3HT: PCBM (1: 1) weight-ratio blend and the effects of annealing temperature and active layer thickness on them. A polymer solar cell array of 9 cells each of area ~6mm2 was built on a single substrate and the variation in photovoltaic parameters were studied. Finally reproducible BHJ solar cells were demonstrated by optimizing active layer thickness and annealing conditions.
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Papers by purushottam jha