Publications by authors named "Poulomi Roy"

17 Publications

  • Page 1 of 1

Epidemiological Characteristics, Ventilator Management, and Clinical Outcome in Patients Receiving Invasive Ventilation in Intensive Care Units from 10 Asian Middle-Income Countries (PRoVENT-iMiC): An International, Multicenter, Prospective Study.

Am J Trop Med Hyg 2021 01 11. Epub 2021 Jan 11.

Nuffield Department of Medicine, University of Oxford, Oxford, United Kingdom.

Epidemiology, ventilator management, and outcome in patients receiving invasive ventilation in intensive care units (ICUs) in middle-income countries are largely unknown. PRactice of VENTilation in Middle-income Countries is an international multicenter 4-week observational study of invasively ventilated adult patients in 54 ICUs from 10 Asian countries conducted in 2017/18. Study outcomes included major ventilator settings (including tidal volume [ ] and positive end-expiratory pressure [PEEP]); the proportion of patients at risk for acute respiratory distress syndrome (ARDS), according to the lung injury prediction score (LIPS), or with ARDS; the incidence of pulmonary complications; and ICU mortality. In 1,315 patients included, median was similar in patients with LIPS < 4 and patients with LIPS ≥ 4, but lower in patients with ARDS (7.90 [6.8-8.9], 8.0 [6.8-9.2], and 7.0 [5.8-8.4] mL/kg Predicted body weight; = 0.0001). Median PEEP was similar in patients with LIPS < 4 and LIPS ≥ 4, but higher in patients with ARDS (five [5-7], five [5-8], and 10 [5-12] cmHO; < 0.0001). The proportions of patients with LIPS ≥ 4 or with ARDS were 68% (95% CI: 66-71) and 7% (95% CI: 6-8), respectively. Pulmonary complications increased stepwise from patients with LIPS < 4 to patients with LIPS ≥ 4 and patients with ARDS (19%, 21%, and 38% respectively; = 0.0002), with a similar trend in ICU mortality (17%, 34%, and 45% respectively; < 0.0001). The capacity of the LIPS to predict development of ARDS was poor (ROC AUC of 0.62, 95% CI: 0.54-0.70). In Asian middle-income countries, where two-thirds of ventilated patients are at risk for ARDS according to the LIPS and pulmonary complications are frequent, setting of is globally in line with current recommendations.
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http://dx.doi.org/10.4269/ajtmh.20-1177DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7941813PMC
January 2021

T cell repertoire analysis suggests a prominent bystander response in human cardiac allograft vasculopathy.

Am J Transplant 2021 04 26;21(4):1465-1476. Epub 2020 Oct 26.

Columbia Center for Translational Immunology, Columbia University Irving Medical Center, New York, New York.

T cells are implicated in the pathogenesis of cardiac allograft vasculopathy (CAV), yet their clonality, specificity, and function are incompletely defined. Here we used T cell receptor β chain (TCRB) sequencing to study the T cell repertoire in the coronary artery, endomyocardium, and peripheral blood at the time of retransplant in four cases of CAV and compared it to the immunoglobulin heavy chain variable region (IGHV) repertoire from the same samples. High-dimensional flow cytometry coupled with single-cell PCR was also used to define the T cell phenotype. Extensive overlap was observed between intragraft and blood TCRBs in all cases, a finding supported by robust quantitative diversity metrics. In contrast, blood and graft IGHV repertoires from the same samples showed minimal overlap. Coronary infiltrates included CD4 and CD8 memory T cells expressing inflammatory (IFNγ, TNFα) and profibrotic (TGFβ) cytokines. These were distinguishable from the peripheral blood based on memory, activation, and tissue residency markers (CD45RO, CTLA-4, and CD69). Importantly, high-frequency rearrangements were traced back to endomyocardial biopsies (2-6 years prior). Comparison with four HLA-mismatched blood donors revealed a repertoire of shared TCRBs, including a subset of recently described cross-reactive sequences. These findings provide supportive evidence for an active local intragraft bystander T cell response in late-stage CAV.
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http://dx.doi.org/10.1111/ajt.16333DOI Listing
April 2021

Bismuth iron molybdenum oxide solid solution: a novel and durable electrocatalyst for overall water splitting.

Chem Commun (Camb) 2020 Jul;56(53):7293-7296

Materials Processing & Microsystems Laboratory, CSIR - Central Mechanical Engineering Research Institute (CMERI), Mahatma Gandhi Avenue, Durgapur 713209, West Bengal, India. and Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, Uttar Pradesh, India.

The drive for finding active bifunctional electrocatalysts for efficient overall water splitting continues in order to extract energy in the form of hydrogen as a clean fuel. Bismuth iron molybdenum oxide solid solution, composed of orthorhombic Bi2MoO6 as the major component and monoclinic Bi3(FeO4)(MoO4)2 as the minor component, has been identified as a potential electrocatalyst for the first time.
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http://dx.doi.org/10.1039/d0cc01931cDOI Listing
July 2020

Ammonia-Assisted Growth of CoSn(OH) Nanostructures and Their Electrochemical Performances for Supercapacitor.

J Nanosci Nanotechnol 2019 May;19(5):2755-2761

Department of Chemistry, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India.

In this work, ammonia-assisted one step growth of SnO₂ and mixed metal hydroxide CoSn(OH) on Ni foam is illustrated. The nanostructured films grown on Ni foam are highly porous in nature. The CoSn(OH) nanostructures were deposited using three different molar ratios of Sn/Co precursors i.e., 1:1, 1:2 and 2:1 and their performances as supercapacitor have been investigated and compared with pristine SnO₂. Interestingly, the CoSn(OH) thin films prepared with 1:2 molar ratio of Sn/Co showed remarkably high areal capacitance and good cyclic stability. It is believed that the presence of different metal cations and their valence states along with the porous nanostructure makes the material outstanding as supercapacitor. The highest areal capacitance of 4189 mF cm was obtained at a current density of 2 mA cm for CoSn(OH) thin films offering an excellent cyclic stability with a capacity retention of 90.3% after 2000 cycles.
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http://dx.doi.org/10.1166/jnn.2019.15829DOI Listing
May 2019

Facile synthesis of flower-like morphology CuCoO for a high-performance supercapattery with extraordinary cycling stability.

Chem Commun (Camb) 2018 Oct;54(87):12400-12403

Department of Chemistry, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkhand, India.

The partial replacement of Co by Cu in cobaltite to give Cu0.27Co2.73O4 with unique flower-like morphology is found to be very beneficial for supercapacitor-battery hybrid applications. The 3D architecture of the material on a conductive substrate resulted in outstanding supercapattery performance. Asymmetric assembly of the material with activated carbon in a two-electrode system delivered high energy and power densities as well as a high specific capacity. The device also showed excellent cycling stability over 20 000 cycles, with a capacity retention value of 86.9%.
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http://dx.doi.org/10.1039/c8cc04625eDOI Listing
October 2018

Deposition of Tin Oxide Thin Films by Successive Ionic Layer Adsorption Reaction Method and Its Characterization.

J Nanosci Nanotechnol 2018 Apr;18(4):2569-2575

Department of Chemistry, Birla Institute of Technology, Mesra, Ranchi 835215, Jharkand, India.

Tin oxide thin films were uniformly deposited by successive ionic layer adsorption reaction (SILAR) method on glass substrates using ethylene diamine as a complexing agent. The proper annealing treatment in air converts as-deposited amorphous films into crystalline and removes defects, reducing strain in the crystal lattice. The films were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Atomic Force Microscopy (AFM), Fourier Transform Infrared (FTIR) spectroscopy. The film shows good optical transparency in the range of 200-1000 nm wavelength and electrical resistivity decreases upon annealing.
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http://dx.doi.org/10.1166/jnn.2018.14301DOI Listing
April 2018

Nb doped TiO2 nanotubes for enhanced photoelectrochemical water-splitting.

Nanoscale 2011 Aug 14;3(8):3094-6. Epub 2011 Jul 14.

Department of Materials Science, LKO, University of Erlangen-Nuremberg, Martensstr. 7, 91058 Erlangen, Germany.

Nanostructured titanium dioxide is one of the classic materials for photoelectrochemical water splitting. In the present work we dope TiO(2) nanotube anodes. For this, various low concentration bulk-Nb-doped TiO(2) nanotube layers were grown by self-organizing anodization of Ti-Nb alloys. At Nb-contents around 0.1 at%, and after an adequate heat-treatment, a strongly increased and stable photoelectrochemical water-splitting rate is obtained.
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http://dx.doi.org/10.1039/c1nr10539fDOI Listing
August 2011

Oxide nanotubes on Ti-Ru alloys: strongly enhanced and stable photoelectrochemical activity for water splitting.

J Am Chem Soc 2011 Apr 29;133(15):5629-31. Epub 2011 Mar 29.

Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Martensstrasse 7, D-91058 Erlangen, Germany.

The present work shows a significant enhancement of the photoelectrochemical water-splitting performance of anodic TiO(2) nanotube layers grown on low concentration (0.01-0.2 at% Ru) Ti-Ru alloys. Under optimized preparation conditions (0.05 at% Ru, 450 °C annealing) the water splitting rate of the oxide tubes could be 6-fold increased. Moreover, the beneficial effect is very stable with illumination time; this is in contrast to other typical doping approaches of TiO(2).
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http://dx.doi.org/10.1021/ja110638yDOI Listing
April 2011

TiO2 nanotubes: synthesis and applications.

Angew Chem Int Ed Engl 2011 Mar 10;50(13):2904-39. Epub 2011 Mar 10.

Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Erlangen, Germany.

TiO(2) is one of the most studied compounds in materials science. Owing to some outstanding properties it is used for instance in photocatalysis, dye-sensitized solar cells, and biomedical devices. In 1999, first reports showed the feasibility to grow highly ordered arrays of TiO(2) nanotubes by a simple but optimized electrochemical anodization of a titanium metal sheet. This finding stimulated intense research activities that focused on growth, modification, properties, and applications of these one-dimensional nanostructures. This review attempts to cover all these aspects, including underlying principles and key functional features of TiO(2), in a comprehensive way and also indicates potential future directions of the field.
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http://dx.doi.org/10.1002/anie.201001374DOI Listing
March 2011

Anodic mesoporous TiO2 layer on Ti for enhanced formation of biomimetic hydroxyapatite.

Acta Biomater 2011 Apr 12;7(4):1873-9. Epub 2010 Nov 12.

Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Erlangen, Germany.

Ti surfaces can be very efficiently coated by a robust (μm thick) mesoporous titania layer (MTL). These coatings are produced by anodization of Ti at elevated temperature in a glycerol/K(2)HPO(4) electrolyte, followed by an appropriate etching process. In the present work we examine these layers with regard to their ability to form hydroxyapatite. Immersion tests in two types of simulated body fluids (Kokubo SBF and Bohner and Lemaitre SBF) combined with scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy investigations show that these MTL layers lead to a significant enhancement of HAp formation and anchoring in the structure compared with non-coated or even nanotubular Ti surface coatings (these were recently reported to be the most efficient in terms of HAp formation).
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http://dx.doi.org/10.1016/j.actbio.2010.11.011DOI Listing
April 2011

TiO2 nanotubes and their application in dye-sensitized solar cells.

Nanoscale 2010 Jan 4;2(1):45-59. Epub 2009 Dec 4.

Department of Materials Science, University of Erlangen-Nürnberg, Martensstrasse 7, Erlangen, Germany.

The present article reviews the current status of using TiO(2) nanotubes in Grätzel-type, dye-sensitized solar cells and extends the overview with the latest results and findings. Critical factors in tube geometry (length, diameter, top morphology), crystal structure (amorphous, anatase, rutile) as well as factors affecting dye loading or electron mobility are addressed. The highest solar cell efficiencies today for pure nanotube systems reach approximately 4% while for some mixed systems, around 7% has been reported. For both systems significant room for enhancement is anticipated and some key points and strategies for improvement are outlined.
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http://dx.doi.org/10.1039/b9nr00131jDOI Listing
January 2010

Size-selective separation of macromolecules by nanochannel titania membrane with self-cleaning (declogging) ability.

J Am Chem Soc 2010 Jun;132(23):7893-5

Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany.

We report on a simple and self-organizing process for the fabrication of TiO(2) nanochannel membranes with a channel width of 8-10 nm that can be used for size selective separation of macromolecules (proteins). The membrane, consisting of self-aligned oxide channels, is formed by complete anodization of a thin Ti foil under specific electrochemical conditions in a glycerol-phosphate electrolyte. Due to self-cleaning properties of TiO(2), clogged membranes (for example due to extended use) can easily be fully reopened and thus are reusable. As the TiO(2) after anodic formation directly contains anatase crystallites (the most photoactive TiO(2) crystal form) no thermal treatment of the membrane is required (avoiding the danger of thermally induced cracking).
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http://dx.doi.org/10.1021/ja102712jDOI Listing
June 2010

Anodic formation of thick anatase TiO2 mesosponge layers for high-efficiency photocatalysis.

J Am Chem Soc 2010 Feb;132(5):1478-9

Department of Materials Science, WW4-LKO, University of Erlangen-Nuremberg, Martensstrasse 7, D-91058 Erlangen, Germany.

We report a process for the fabrication of an anatase TiO(2) mesosponge (TMS) layer by an optimized Ti anodization process in a hot glycerol electrolyte followed by a suitable etching process. Such layers can easily be grown to >10 microm thickness and have regular channels and structural features in the 5-20 nm range. The layers show high photocatalytic activity and are mechanically very robust. The layers therefore open new pathways to the wide field of TiO(2)(anatase) applications.
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http://dx.doi.org/10.1021/ja910045xDOI Listing
February 2010

Voltage-induced payload release and wettability control on TiO2 and TiO2 nanotubes.

Angew Chem Int Ed Engl 2010 ;49(2):351-4

Department of Material Science WW-4, LKO, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany.

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http://dx.doi.org/10.1002/anie.200905111DOI Listing
March 2010

Formation of a non-thickness-limited titanium dioxide mesosponge and its use in dye-sensitized solar cells.

Angew Chem Int Ed Engl 2009 ;48(49):9326-9

Department of Materials Science and Engineering, WW4-LKO, University of Erlangen-Nuremberg, Martensstrasse 7, 91058 Erlangen, Germany.

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http://dx.doi.org/10.1002/anie.200904455DOI Listing
February 2010

Solvothermal growth of flower-like morphology from nanorods of copper sulfides.

J Nanosci Nanotechnol 2008 Mar;8(3):1523-7

Inorganic Materials and Nanocomposite Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India.

The present work reports the effect of reaction time on solvothermal synthesis of copper sulfides from CuCl2 x 2H2O and thiourea with various compositions and morphologies using ethylenediamine as solvent at 120 degrees C. X-ray diffraction patterns of the products at different durations shows the development of different stoichiometric composition of copper sulfides in where Cu:S ratio increases from 1.39 to 1.79 indicating transformation of Cu39S28 to Cu7S4. As inferred by EDX and XPS studies of the final products. SEM shows the growth of bundles of nanorods of length approximately 1 microm and diameter in nanometer range are observed after 6 h. On increasing the reaction duration to 9 h, nanorods tends to combines with each other and growth occurs in six directions and after 12 h leads to the formation of flower-like morphology of copper sulfide. The optical properties of these products also have been studied.
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March 2008

A simple hydrothermal method for the growth of Bi2Se3 nanorods.

Nanotechnology 2006 Mar 27;17(6):1700-5. Epub 2006 Feb 27.

Inorganic Materials and Nanocomposite Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur-721302, India.

Bi2Se3 nanorods have been synthesized through a simple hydrothermal reduction approach. The nanorods formed were ≈10 nm in diameter and 100-200 nm in length. XRD characterization suggested that the product consisted of the hexagonal phase of pure Bi2Se3. EDX and XPS studies further confirmed the composition and purity of the product. A possible mechanism for the reaction is proposed, where Bi2Se3 microsheets are presumed to be the intermediate for the formation of the nanorods. The effect of solvent on the morphology of the final product is discussed, where, in the presence of aprotic solvent DMF, nanoparticle formation is observed. A bandgap of 2.25 eV is observed from the UV-visible absorption spectra.
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http://dx.doi.org/10.1088/0957-4484/17/6/026DOI Listing
March 2006
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