Extractive Desulfurization of Liquid Fuels by Energy Efficient Green Thiazolium based Ionic Liquids

Dharaskar, Swapnil A.,Wasewar, Kailas L.,Varma, Mahesh N.,Shende, Diwakar Z.,Yoo, Chang Kyoo American Chemical Society 2014 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.53 No.51

<P>In the present paper, experimental data on extractive desulfurization of liquid fuel using 3-butyl-4-methylthiazolium thiocyanate [BMTH]SCN is presented. The Fourier transform infrared (FTIR), <SUP>1</SUP>H NMR, and <SUP>13</SUP>C NMR analyses have been discussed for the molecular confirmation of synthesized [BMTH]SCN. Further, conductivity, solubility, and viscosity analyses of [BMTH]SCN were performed. The effects of reaction time, reaction temperature, sulfur compounds, ultrasonication, and recycling of [BMTH]SCN without regeneration on removal of dibenzothiophene from liquid fuel were also investigated. In the extractive desulfurization process, the removal of dibenzothiophene in octane was 81.2% for mass ratio of 1:1 in 30 min at 30 °C under the mild reaction conditions. Thiazolium ionic liquids could be reused five times without a significant decrease in activity. Also, the desulfurization of real fuels, multistage extraction was examined. The data and results provided in present paper explore the significant insights of thiazolium based ionic liquids as novel extractant for extractive desulfurization of liquid fuels.</P>

Synthesis, characterization, and application of novel trihexyl tetradecyl phosphonium bis (2,4,4-trimethylpentyl) phosphinate for extractive desulfurization of liquid fuel

Dharaskar, S.A.,Wasewar, K.L.,Varma, M.N.,Shende, D.Z.,Tadi, K.K.,Yoo, C.K. Elsevier Scientific Pub. Co 2014 Fuel processing technology Vol.123 No.-

In present paper experimental data on extractive desulfurization of liquid fuel using trihexyl tetradecyl phosphonium bis (2,4,4-trimethyl pentyl) phosphinate has been presented. The FTIR, <SUP>1</SUP>H NMR, <SUP>13</SUP>C NMR, <SUP>31</SUP>P NMR, and ESR have been discussed for the molecular confirmation of synthesized phosphonium based ionic liquid. Further, conductivity, solubility, and viscosity analyses of phosphonium ionic liquids were carried out. The effects of reaction time, reaction temperature, sulfur compounds, ultrasonication, and recycling of ionic liquid without regeneration on removal of dibenzothiophene from liquid fuel were also investigated. In extractive desulfurization process, the removal of dibenzothiophene in n-dodecane was 79.5% for mass ratio of 1:1 in 30min at 30<SUP>o</SUP>C under the mild reaction conditions. Phosphonium ionic liquids could be reused five times without a significant decrease in activity. Also, the desulfurization of real fuels, multistage extraction was examined. The data and results provided in present paper explore the significant insights of phosphonium based ionic liquids as novel extractant for extractive desulfurization of liquid fuels.

Synthesis, characterization and application of 1-butyl-3-methylimidazolium tetrafluoroborate for extractive desulfurization of liquid fuel

Dharaskar, S.A.,Wasewar, K.L.,Varma, M.N.,Shende, D.Z.,Yoo, C. Elsevier ; King Saud University 2016 Arabian journal of chemistry Vol.9 No.4

<P>In the present paper the experimental data of extractive desulfurization of liquid fuel using 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM]BF4 have been presented. The data of FTIR, 1 H NMR and C-13 NMR have been discussed for the molecular confirmation of synthesized [BMIM]BF4. Further, the thermal properties, conductivity, solubility, and viscosity analysis of the [BMIM]BF4 were carried out. The effects of reaction time, reaction temperature, sulfur compounds, and recycling of ionic liquid without regeneration on dibenzothiophene removal of liquid fuel were presented. In extractive desulfurization process, the removal of dibenzothiophene in n-dodecane was 73.02% for mass ratio of 1: 1 in 30 min at 30 degrees C under the mild reaction conditions. The ionic liquids could be reused four times without a significant decrease in activity. Also, the desulfurizations of real fuels, multistage extraction were presented. The data and results provided in the present paper explore the significant insights of imidazoled ILs for extractive desulfurization of liquid fuels. (C) 2013 Production and hosting by Elsevier B.V. on behalf of King Saud University.</P>

Intracranial Metastasis of Extracranial Chondrosarcoma: Systematic Review With Illustrative Case

( Charles E. Mackel ),( Harry Rosenberg ),( Hemant Varma ),( Erik J. Uhlmann ),( Rafael A. Vega ),( Ron L. Alterman ) 대한뇌종양학회·대한신경종양학회·대한소아뇌종양학회 2023 Brain Tumor Research and Treatment Vol.11 No.2

Background Cerebral chondrosarcoma metastases are rare and aggressive neoplasms. The rarity of presentation has precluded rigorous analysis of diagnosis, risk factors, treatment, and survival. We analyzed every reported case through exhaustive literature review. We further present the first case with Maffucci syndrome. Methods Three databases, PubMed, Embase, and Google Scholar, and crossed references were queried for cerebral chondrosarcoma metastases. Extracted variables included demographics, risk factors, tumor characteristics, interventions, and outcomes. Univariate and multivariate analyses were performed. Results Fifty-six patients were included from 1,489 literature results. The average age at brain metastasis was 46.6±17.6 years and occurred at a median of 24±2.8 months from primary diagnosis. Primary tumor histology (dedifferentiated 5.0±1.5 months, mesenchymal 24±3.0 months, conventional 41±7.4 months, p<0.05) and grade (low grade 54±16.7 months vs. high-grade 10±6.4 months, p<0.001) correlated with time interval until brain metastasis. A multiple enchondromatosis syndrome occurred in 13.2% of cases. At time of brain metastases diagnosis, extracranial metastases were identified in 76.2% of cases. Median survival after the development of brain metastasis was 2.0±0.78 months with a 1-year survival of 10.0%. On regression analysis, surgery reduced brain metastasis mortality risk and radiation trended towards reduced mortality risk (surgery: hazard ratio [HR] 0.22, 95% confidence interval [CI] 0.064-0.763, p=0.017; radiation: HR 0.31, 95% CI 0.091-1.072, p=0.064). Conclusion We present a systematic review of cerebral chondrosarcoma metastases. Primary tumor histology and grade correlate with time until cerebral metastasis. Following cerebral metastasis, these tumors have poor prognosis and modestly benefit from surgery.

Oxide Scale Characterization and Study of Oxidation Kinetics in T91 Steel Exposed to Dry Air at High Temperatures (873–1073 K)

S. Das,S. Sanyal,P. Halder,A. Varma,Y. Ravi Kumar,S. Mandal 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

In this study, the oxidation response of a T91 steel in dry air environment has been investigated by performing cyclic oxidationtests at 873, 973 and 1073 K for a total duration of 1000 h with intermediate intervals. The temperature range for thisstudy is chosen to be higher than the operating temperature range of the alloy to accelerate the oxidation kinetics. Developinga comprehensive understanding of the mechanisms and kinetics involved at such accelerated oxidation environmentswould help to formulate better strategies for countering oxidation related failure events. The results of this study showedthat the oxidation rate is greatly influenced by temperature as well as exposure time, and follows a near-parabolic rate law. Characterization of the oxide scales revealed formation of dual oxide layers where the inner layer is primarily rich in Feand Cr, and the outer layer in Fe only. At 1073 K, formation of cracks can be observed in the oxide scales after 24 h, whichbecame more severe after 1000 h. The oxidation kinetics, when fitted to an Arrhenius type equation, can be associated withactivation energy (Q) and parabolic rate constant (kp) values. The Q values lie within 104–109 kJ/mol, whereas the kp valuesincrease with temperature due to increase in the reaction rate. The kinetic equation developed based on the Q and kp valuescan be used to predict the thickness (inner, outer and overall) of the oxide scales in T91 steel at any temperature and timewithin the studied ranges.

Comparison of Interferon-γ Release Assays and the Tuberculin Skin Test for Diagnosis of Tuberculosis in Human Immunodeficiency Virus: A Systematic Review

( Kristen Overton ),( B. Sc. ),( M. B. B. S. ),( M. P. H. T. M. ),( Rick Varma ),( Mb. Ch. B. ),( M. R. C. P. (u. K. ) ),( F. A. Ch. S. H. M. ),( Dip. Hiv ),( Dip. Gum,D. T. M. &h. ),( D. F. F. P. ),( 대한결핵 및 호흡기학회 2018 Tuberculosis and Respiratory Diseases Vol.81 No.1

Background: It remains uncertain if interferon-γ release assays (IGRAs) are superior to the tuberculin skin test (TST) for the diagnosis of active tuberculosis (TB) or latent tuberculosis infection (LTBI) in immunosuppressed populations including people with human immunodeficiency virus (HIV) infection. The purpose of this study was to systematically review the performance of IGRAs and the TST in people with HIV with active TB or LTBI in low and high prevalence TB countries. Methods: We searched the MEDLINE database from 1966 through to January 2017 for studies that compared results of the TST with either the commercial QuantiFERON-TB Gold in Tube (QFTGT) assay or previous assay versions, the T-SPOT.TB assay or in-house IGRAs. Data were summarized by TB prevalence. Tests for concordance and differences in proportions were undertaken as appropriate. The variation in study methodology was appraised. Results: Thirty-two studies including 4,856 HIV subjects met the search criteria. Fourteen studies compared the tests in subjects with LTBI in low TB prevalence settings. The QFTGT had a similar rate of reactivity to the TST, although the first-generation version of that assay was reactive more commonly. IGRAs were more frequently positive than the TST in HIV infected subjects with active TB. There was considerable study methodology and population heterogeneity, and generally low concordance between tests. Both the TST and IGRAs were affected by CD4 T-cell immunodeficiency. Conclusion: Our review of comparative data does not provide robust evidence to support the assertion that the IGRAs are superior to the TST when used in HIV infected subjects to diagnose either active TB or LTBI.

The influence of in situ deposition techniques on PbS seeded CdS/CdSe for enhancing the photovoltaic performance of quantum dot sensitized solar cells

Punnoose, D.,Suh, S.M.,Kim, B.J.,kim, S.k.,Kumar, Ch.S.S.P.,Rao, S.S.,Thulasi-Varma, C.V.,Reddy, A.E.,Chung, S.H.,Kim, H.J. Elsevier Sequoia 2016 Journal of Electroanalytical Chemistry Vol.773 No.-

<P>The deposition techniques of quantum dots (QDs) have great influence on the photovoltaic performances of quantum dot sensitised solar cells (QDSSCs). In this study, we report CdS/CdSe sensitised TiO2 solar cells focussing on the influence of two commonly used in situ QD deposition techniques (SILAR: successive ionic layer adsorption and reaction and CBD: chemical bath deposition). In addition to this, the QDSSC performance is enhanced due to better light harvesting capability of PbS quantum dots and makes large accumulation of photo-injected electrons in the conduction band of TiO2. When compared to power conversion efficiency (PCE) of 4.58% was obtained for PbS/CBD-CdS/CBD-CdSe cells when compared to PbS/SILAR-CdS/SILAR-CdSe. With chemical bath deposition, we achieved high surface coverage of QDs, which contributes to the increase in photocurrent,open circuit voltage and fill factor. Impedance spectroscopy revealed that the PbS/CBD-CdS/CBD-CdSe reduces recombination and increases charge collection efficiency and a long electron lifetime was achieved. To associate the assembling of QDs with the performance of QDSSCs a methodical characterization of morphology, optical and electro-chemical properties and its stability has been studied. We achieved PbS seeded CBD highlighting its robust consequences for the performance of QDSSCs. (C) 2016 Elsevier B.V. All rights reserved.</P>

Influence of ion implantation on depth dependent phase transition in TiO2 films, anatase nanostructures and photo-absorption behavior

Manna Ashis K.,Joshi Shalik R.,Satpati B.,Dash P.,Chattaraj Ananya,Srivastava S.K.,Kanjilal A.,Kanjilal D.,Varma Shikha 한국물리학회 2022 Current Applied Physics Vol.43 No.-

The present study explores the role of Ti ion implantation in structural phase transition in TiO2 thin films. Raman and TEM results reveal that after implantation Rutile phase in films increases at the expense of Anatase nanostructures. Though the as-deposited films display the presence of bigger anatase nanoparticles, after implantation, predominantly phonon confined smaller (~ 8 nm in size) anatase nanostructures are observed. GIXRD and Raman results further reflect presence of a critical fluence, 1 × 1013 ions/cm2, where the initial transformation from anatase to Rutile phase is observed. The role of Oxygen vacancies, in this transformation, has been explored here by XPS. Modifications in UV–Vis and Bandgap results show rich behavior which also reflects phase transformation at the critical fluence. Results further indicate that the phase transition gets first initiated deeper in the film and later on the surface. Interestingly, aggregation of larger Anatase nano-particles appears to be responsible for the structural transformation as observed here.