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Kiruthika S, Sundar P, Ravindran P. Structural phase stability and thermodynamical properties of transition metal complex hydrides Na2MgTMH7 (TM=Sc−Cu) for hydrogen storage applications. J SOLID STATE CHEM 2023. [DOI: 10.1016/j.jssc.2023.123867] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Parthasarathy D, Chandragiri S, Thampi SP, Ravindran P, Basavaraj MG. An experimental and theoretical study of the inward particle drift in contact line deposits. Soft Matter 2022; 18:2414-2421. [PMID: 35266493 DOI: 10.1039/d2sm00142j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The coffee ring effect, which refers to the formation of a ring-like deposit along the periphery of a dried particle laden sessile drop, is a commonly observed phenomenon. The migration of particles from the interior to the edge of a drying drop as a result of evaporation driven flow directed outwards, is well studied. In this article, we document the inward drift of a coffee stain, which is governed by the descent of the water-air interface of the drying drop due to solvent evaporation. A combination of experimental study and model predictions is undertaken to elucidate the effect of the diameter of particles in the drying drop, the wettability of the substrate on which the drop resides, and the concentration of particles on the inward drift of the coffee stain. This work also suggests a novel method to estimate the coefficient of friction between the particles and the substrate.
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Affiliation(s)
- Dinesh Parthasarathy
- Polymer Engineering and Colloid Science Laboratory (PECS), Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India.
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India.
| | - Santhan Chandragiri
- Polymer Engineering and Colloid Science Laboratory (PECS), Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India.
| | - Sumesh P Thampi
- Polymer Engineering and Colloid Science Laboratory (PECS), Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India.
| | - Parag Ravindran
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India.
| | - Madivala G Basavaraj
- Polymer Engineering and Colloid Science Laboratory (PECS), Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai - 600036, India.
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Parthasarathy D, Thampi SP, Ravindran P, Basavaraj MG. Further Insights into Patterns from Drying Particle Laden Sessile Drops. Langmuir 2021; 37:4395-4402. [PMID: 33797915 DOI: 10.1021/acs.langmuir.1c00512] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The evaporation of colloidal dispersions is an elegant and straightforward route to controlled self-assembly of particles on a solid surface. In particular, the evaporation of particle laden drops placed on solid substrates has received considerable attention for more than two decades. Such particle filled drops upon complete evaporation of the solvent leave behind a residue, commonly called particulate deposit pattern. In these patterns, typically, more particles accumulate at the edge compared to the interior, a feature observed when coffee drops evaporate. Consequently, such evaporative patterns are called coffee stains. In this article, the focus is on the evaporation of highly dilute suspension drops containing particles of larger diameters ranging from 3 to 10 μm drying on solid substrates. This helps us to investigate the combined role of gravity-driven settling of particles and capillary flow-driven particle transport on pattern formation in drying drops. In the highly dilute concentration limit, the evaporative patterns are found to show a transition, from a monolayer deposit that consists of a single layer of particles, to a multilayer deposit as a function of particle diameter and initial concentration of particles in the drying drop. Moreover, the spatial distribution of particles as well as the ordering of particles in the deposit patterns are found to be particle size dependent. It is also seen that the order-disorder transition, a feature associated with the organization of particles at the edge of the deposit, observed typically at moderate particle concentrations, disappears at the highly dilute concentrations considered here. The evaporation of drops containing particles of 10 μm diameter, where the effect of gravity on the particle becomes significant, leads to uniform deposition of particles, i.e, suppression of the coffee-stain effect and to the formation of two-dimensional percolating networks.
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Affiliation(s)
- Dinesh Parthasarathy
- Polymer Engineering and Colloid Science(PECS) Laboratory, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
| | - Sumesh P Thampi
- Polymer Engineering and Colloid Science(PECS) Laboratory, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
| | - Parag Ravindran
- Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
| | - Madivala G Basavaraj
- Polymer Engineering and Colloid Science(PECS) Laboratory, Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai 600036, Tamil Nadu, India
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Augustine AM, Ravindran P. Role of W-site substitution on mechanical and electronic properties of cubic tungsten carbide. J Phys Condens Matter 2020; 32:145701. [PMID: 31855859 DOI: 10.1088/1361-648x/ab6428] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In order to understand the role of W-site substitution on properties of cubic tungsten carbide ([Formula: see text]-WC), we have investigated the structural, mechanical, and electronic properties of WXC2 (X = Si, Sc, Ti, V, Cr, Ge, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, Sn, Hf, Ta, Re, Os, Ir, Pt, Th, U) using first principles calculations based on density functional theory, within generalized gradient approximation. The structural optimization has carried out for all these compounds using force as well as stress minimization. The optimized structural parameters for experimentally known compounds are in good agreement with the available x-ray diffraction measurements and structural parameters for nineteen WXC2 compounds are newly predicted. The W-site substitution of the above-listed elements into [Formula: see text]-WC reduces the symmetry of the primitive lattice to tetragonal structure. The heat of formation ([Formula: see text]) and the mechanical stability studies are carried out to investigate the stability of these systems. The single-crystal elastic constants c ij , elastic moduli of the polycrystalline aggregates, anisotropy in elastic constants and related properties of the WXC2 materials have calculated and discussed in detail. The hardness of the above materials is predicted using two different criteria, based on the softest elastic mode as well as the Pugh's modulus ratio. There is a correlation in the hardness predicted from these two approaches except in the case of [Formula: see text]-WC. The chemical bonding interaction between the constituents is analysed using the density of states, crystal orbital Hamiltonian population, and charge density for selected systems. All these compounds are predicted to be metal and our calculations suggest that W-site substitutions do not improve the hardness of [Formula: see text]-WC. However, from the heat of formation studies, we have identified five new stable compounds such as CrWC2, NbWC2, ScWC2, YWC2, and UWC2 with reasonably good hardness and those need experimental verifications.
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Affiliation(s)
- Anu Maria Augustine
- Department of Physics, Central University of Tamil Nadu, Thiruvarur 610005, India. Simulation Center for Atomic and Nanoscale MATerials, Central University of Tamil Nadu, Thiruvarur, 610005, India
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Abstract
Two dimensional nitrogenated holey graphene (2D-C2N) is often considered as an ideal material for hydrogen storage applications owing to its lower mass density and high surface-to-volume ratio. As the interaction between H2 and pristine 2D-C2N is very weak with an adsorption energy of only 0.10 eV per H2, it is important to improve it through appropriate materials design. Using density functional theory calculations, we investigated the hydrogen storage properties of metal (M = Mg, Ca, Ti, V, Mn, Fe, Co, Ni, Cu, and Zn) decorated 2D-C2N. From this study, we found that M binding energy on 2D-C2N is greater than the cohesive energy of the respective bulk metals, indicating that the metal is strongly bonded with the 2D-C2N, which rules out the metal clustering issue. In particular, 2D-C2N with Mg decoration leads to 6.79 wt% hydrogen storage capacity with a desirable adsorption energy which is above the Department of Energy's target. The electronic structure analyses show that the Mg decoration leads to a semiconductor-to-metallic transition in 2D-C2N. Our chemical bonding analyses through partial density of states, charge density, electron localization function, charge transfer, and Bader effective charge confirm the presence of an iono-covalent character for Mg decorated 2D-C2N. This indicates that the H2 molecules are adsorbed by a polarization mechanism. Overall, our results suggest that Mg decorated 2D-C2N is a promising candidate for potential hydrogen storage applications.
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Affiliation(s)
- R Varunaa
- Department of Physics, Central University of Tamil Nadu, Thiruvarur, Tamil Nadu 610005, India. and Simulation Center for Atomic and Nanoscale MATerials (SCANMAT), Central University of Tamil Nadu, Thiruvarur, Tamil Nadu 610005, India
| | - P Ravindran
- Department of Physics, Central University of Tamil Nadu, Thiruvarur, Tamil Nadu 610005, India. and Simulation Center for Atomic and Nanoscale MATerials (SCANMAT), Central University of Tamil Nadu, Thiruvarur, Tamil Nadu 610005, India and Center for Materials Science and Nanotechnology and Department of Chemistry, University of Oslo, Box 1033 Blindern, N-0315 Oslo, Norway
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Singh R, Gupta V, Malhotra B, Singh S, Ravindran P, Meena D, Gupta J, Mathur VK, Mathur RP, Singh S, Sharma P, Sharma H, Bhandari S, Gupta N, Sapkal G, Mourya DT, Speer MD. Cluster containment strategy: addressing Zika virus outbreak in Rajasthan, India. BMJ Glob Health 2019; 4:e001383. [PMID: 31565402 PMCID: PMC6747920 DOI: 10.1136/bmjgh-2018-001383] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2018] [Revised: 05/25/2019] [Accepted: 06/01/2019] [Indexed: 01/04/2023] Open
Abstract
India is at risk of Zika virus transmission due to high prevalence of its vector Aedes aegypti. Rajasthan, a state in the north-west region of India, has also high prevalence of Aedes mosquito. First laboratory confirmed case of Zika virus disease in Rajasthan was reported on 21 September 2018 in Jaipur. The Government of Rajasthan quickly implemented a containment strategy to contain the outbreak and prevent further spread of this disease. Strategy included active human and mosquito surveillance, laboratory testing and sequencing of the virus, integrated vector control measures, intersectoral coordination, risk communication and social mobilisation, all in a predefined geographic area around the epicentre. Timely action with appropriate coordination at all levels with multiple stakeholders contained the outbreak successfully. In all, 159 confirmed cases were reported from in and around the 3 km containment zone in Shastri Nagar area of Jaipur City and routine surveillance. Following this, a specially developed laboratory-based surveillance strategy was put in place to ensure that the disease does not spread beyond the containment zone. No fresh case was reported subsequently within or beyond the containment zone.
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Affiliation(s)
- Ruchi Singh
- Medical & Health GOR, State Microbiologist IDSP Directorate, Medical & Health Services, Jaipur, India
| | - Veenu Gupta
- Medical & Health, Government of Rajasthan, Jaipur, India
| | - Bharti Malhotra
- Microbiology, SMS Medical College and Hospital, Jaipur, India
| | - Sujeet Singh
- National Centre for Disease Control, Ministry of Health and Family Welfare, Government of India, Delhi, India
| | - P Ravindran
- Emergency Medical Relief, Union Government, New Delhi, India
| | - Deepa Meena
- Directorate Medical & Health, Government of Rajasthan, Jaipur, India
| | - Jyoti Gupta
- Directorate Medical & Health, Government of Rajasthan, Jaipur, India
| | - V K Mathur
- Directorate Medical & Health, Government of Rajasthan, Jaipur, India
| | | | - Sunil Singh
- Directorate Medical & Health, Government of Rajasthan, Jaipur, India
| | - Pratibha Sharma
- Microbiology, SMS Medical College and Hospital, Jaipur, India
| | - Himanshu Sharma
- Microbiology, SMS Medical College and Hospital, Jaipur, India
| | | | - Nivedita Gupta
- Epidemiology & communicable diseases, Indian Council of Medical Research, Government of India, Delhi, India
| | | | | | - Maclane Davis Speer
- Directorate Medical & Health, Government of Rajasthan, Jaipur, India.,Public Health, Dickinson College, Carlisle, Pennsylvania, USA
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Mythravaruni P, Ravindran P. The effect of oxidation on the mechanical response of isolated elastin and aorta. J Biomech Eng 2019; 141:2730404. [PMID: 30942830 DOI: 10.1115/1.4043355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2018] [Indexed: 11/08/2022]
Abstract
Oxidation of aorta by hydroxyl radicals produces structural changes in arterial proteins like elastin and collagen, which results in change in the mechanical response of aorta. In this paper, with a view to understand the effect of oxidation on the mechanical behavior of aorta and isolated elastin, a thermodynamically consistent constitutive model is developed within the framework of mixture theory to describe the changes in aorta and isolated elastin with oxidation. The model is then studied under uniaxial extension using experimental data from literature.
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Affiliation(s)
- Pulela Mythravaruni
- Department of Mechanical Engineering, IIT Madras, Chennai 600036; Faculty of Civil and Environmental Engineering, Technion, Israel
| | - Parag Ravindran
- Department of Mechanical Engineering, IIT Madras, Chennai 600036
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Patra L, Pan Z, Chen J, Azuma M, Ravindran P. Metamagnetism stabilized giant magnetoelectric coupling in ferroelectric xBaTiO 3-(1 - x)BiCoO 3 solid solution. Phys Chem Chem Phys 2018; 20:7021-7032. [PMID: 29469917 DOI: 10.1039/c7cp07677k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
In order to establish the correlation between the magnetoelectric coupling and magnetic instability, we have studied the structural, magnetic, and ferroelectric properties of BaTiO3 modified BiCoO3i.e. xBaTiO3-(1 - x)BiCoO3 as a function of BaTiO3 concentration (x) and volume from a series of general-gradient-corrected (GGA), GGA plus onsite Coulomb repulsion (U), full potential, spin-density-functional band-structure calculations within the framework of density functional theory along with synchrotron X-ray diffraction and magnetic measurement studies. G-type antiferromagnetic ordering was found to be energetically favorable among all the considered magnetic configurations for x < 0.45 and higher concentrations stabilize with nonmagnetic (NM) states. We observe metamagnetic spin state transitions associated with paraelectric to ferroelectric transitions as a function of volume and x using synchrotron diffraction and computational studies, indicating a strong magnetoelectric coupling. Specifically for x = 0.33 composition, a pressure induced high spin (HS) to low spin (LS) transition occurs when the volume is compressed below 2.5%. Our orbital-projected density of states show a HS state for Co3+ in the ferroelectric ground state for x < 0.45 and the corresponding paraelectric phase is stable in the NM state due to the stabilization of LS state as evident from our fixed-spin-moment calculations and magnetic measurements. The nature of chemical bonding has been studied using partial density of states, electron localization function, and Born effective charge analysis. High values of spontaneous ferroelectric polarizations are predicted for lower x values which inversely vary with x because of the reduction of tetragonality (c/a) with increase in x which indicates the presence of both spin-lattice and ferroelectricity-lattice coupling. Our partial polarization analysis shows that not only the lone pair at Bi sites but also the d0-ness of Ti4+ ions contribute to the net polarization. Moreover, we find that the HS-LS transition point and magnetoelectric coupling strength can be varied by x.
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Affiliation(s)
- Lokanath Patra
- Department of Physics, Central University of Tamil Nadu, Thiruvarur 610101, India.
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Kishore MA, Ravindran P. Back Cover: Enhanced Photocatalytic Water Splitting in a C2
N Monolayer by C-Site Isoelectronic Substitution (ChemPhysChem 12/2017). Chemphyschem 2017. [DOI: 10.1002/cphc.201700614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- M.R. Ashwin Kishore
- Department of Physics; Central University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
- Simulation Center for Atomic and Nanoscale MATerials (SCANMAT); Central University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
| | - P. Ravindran
- Department of Physics; Central University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
- Simulation Center for Atomic and Nanoscale MATerials (SCANMAT); Central University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
- Department of Materials Science, Central; University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
- Center for Materials Science and Nanotechnology and Department of Chemistry; University of Oslo; Box 1033 Blindern 0315 Oslo Norway
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Kishore MA, Ravindran P. Enhanced Photocatalytic Water Splitting in a C2N Monolayer by C-Site Isoelectronic Substitution. Chemphyschem 2017; 18:1526-1532. [DOI: 10.1002/cphc.201700165] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2017] [Indexed: 11/11/2022]
Affiliation(s)
- M.R. Ashwin Kishore
- Department of Physics; Central University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
- Simulation Center for Atomic and Nanoscale MATerials (SCANMAT); Central University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
| | - P. Ravindran
- Department of Physics; Central University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
- Simulation Center for Atomic and Nanoscale MATerials (SCANMAT); Central University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
- Department of Materials Science, Central; University of Tamil Nadu; Thiruvarur Tamil Nadu 610101 India
- Center for Materials Science and Nanotechnology and Department of Chemistry; University of Oslo; Box 1033 Blindern 0315 Oslo Norway
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Ravindran P, WuiAnn W, LIM Y. SU-F-T-526: A Comparative Study On Gating Efficiency of Varian RPM Device and Calypso System. Med Phys 2016. [DOI: 10.1118/1.4956711] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Kishore MRA, Okamoto H, Patra L, Vidya R, Sjåstad AO, Fjellvåg H, Ravindran P. Theoretical and experimental investigation on structural, electronic and magnetic properties of layered Mn5O8. Phys Chem Chem Phys 2016; 18:27885-27896. [DOI: 10.1039/c6cp04170a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Using density functional theory calculations and NPD measurements, we have identified that Mn5O8is a strongly correlated mixed valent antiferromagnetic metal.
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Affiliation(s)
| | - H. Okamoto
- Center for Materials Science and Nanotechnology and Department of Chemistry
- University of Oslo
- N-0315 Oslo
- Norway
| | - Lokanath Patra
- Department of Physics
- Central University of Tamil Nadu
- Thiruvarur
- India
| | - R. Vidya
- Department of Medical Physics
- Anna University
- Chennai
- India
| | - Anja O. Sjåstad
- Center for Materials Science and Nanotechnology and Department of Chemistry
- University of Oslo
- N-0315 Oslo
- Norway
| | - H. Fjellvåg
- Center for Materials Science and Nanotechnology and Department of Chemistry
- University of Oslo
- N-0315 Oslo
- Norway
| | - P. Ravindran
- Department of Physics
- Central University of Tamil Nadu
- Thiruvarur
- India
- Center for Materials Science and Nanotechnology and Department of Chemistry
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Kron T, Azhari HA, Voon EO, Cheung KY, Ravindran P, Soejoko D, Inamura K, Han Y, Ung NM, TsedenIsh B, Win UM, Srivastava R, Marsh S, Farrukh S, Rodriguez L, Kuo M, Baggarley S, DilipKumara AH, Lee CC, Krisanachinda A, Nguyen XC, Ng KH. Medical physics aspects of cancer care in the Asia Pacific region: 2014 survey results. Australas Phys Eng Sci Med 2015; 38:493-501. [DOI: 10.1007/s13246-015-0373-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 08/24/2015] [Indexed: 11/29/2022]
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Iozzi MF, Vajeeston P, Vidya R, Ravindran P, Fjellvåg H. Structural and electronic properties of transparent conducting delafossite: a comparison between the AgBO2 and CuBO2 families (B = Al, Ga, In and Sc, Y). RSC Adv 2015. [DOI: 10.1039/c3ra47531j] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The Ag-based delafossite transparent conducting oxides are potential p-type materials for transparent electronics. However, they have attracted less attention due to their difficult synthetic chemistry and relatively low conductivity.
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Affiliation(s)
- M. F. Iozzi
- Department of Chemistry
- Center for Materials Sciences and Nanotechnology
- University of Oslo
- N-0315 Oslo
- Norway
| | - P. Vajeeston
- Department of Chemistry
- Center for Materials Sciences and Nanotechnology
- University of Oslo
- N-0315 Oslo
- Norway
| | - R. Vidya
- Department of Chemistry
- Center for Materials Sciences and Nanotechnology
- University of Oslo
- N-0315 Oslo
- Norway
| | - P. Ravindran
- Department of Chemistry
- Center for Materials Sciences and Nanotechnology
- University of Oslo
- N-0315 Oslo
- Norway
| | - H. Fjellvåg
- Department of Chemistry
- Center for Materials Sciences and Nanotechnology
- University of Oslo
- N-0315 Oslo
- Norway
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Manimuthu P, Vidya R, Ravindran P, Fjellvåg H, Venkateswaran C. Observation of direct magneto-dielectric behaviour in Lu3Fe5O12−δ above room-temperature. Phys Chem Chem Phys 2015; 17:17688-98. [DOI: 10.1039/c5cp02719e] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Oxygen vacancy created an intrinsic magneto-dielectric effect in Lu3Fe5O12.
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Affiliation(s)
- P. Manimuthu
- Department of Nuclear Physics
- University of Madras
- Chennai-600 025
- India
| | - R. Vidya
- Institute of Mathematical Sciences
- Chennai-600 113
- India
- Centre for Materials Science and Nanotechnology
- Department of Chemistry
| | - P. Ravindran
- Centre for Materials Science and Nanotechnology
- Department of Chemistry
- University of Oslo
- N-0315 Oslo
- Norway
| | - H. Fjellvåg
- Centre for Materials Science and Nanotechnology
- Department of Chemistry
- University of Oslo
- N-0315 Oslo
- Norway
| | - C. Venkateswaran
- Department of Nuclear Physics
- University of Madras
- Chennai-600 025
- India
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Tan KK, Ravindran P, Young CJ, Solomon MJ. The extent of inflammation is a predictor for pouch-related complications in ileal pouches in patients with ulcerative or indeterminate colitis. Colorectal Dis 2014; 16:620-5. [PMID: 24635999 DOI: 10.1111/codi.12614] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/03/2013] [Accepted: 01/16/2014] [Indexed: 12/24/2022]
Abstract
AIM Limited data are available on the relationship between the histological features of the resected specimens in patients with ulcerative colitis (UC) or indeterminate colitis (IC) and the outcome of restorative proctocolectomy. The aim of our study was to determine if the histological features of the resected specimen in patients with UC and IC can predict ileal-pouch-related outcome. METHOD A review of all patients who had a restorative proctocolectomy created following completion proctectomy or proctocolectomy for UC and IC was performed. RESULTS Between 1992 and 2011, 142 patients (132 with UC and 10 with IC) were reviewed. After a median follow-up of 36 (3-149) months, 51 (35.9%) developed a pouch-related complication. Forty-two (29.7%) developed pouchitis while three (2.1%) developed a pouch-cutaneous fistula. Four (2.8%) had pouch failure, while stricture of the anastomosis was seen in three (2.1%) patients. The presence of extension of the inflammation into the muscularis propria of the resected specimen was associated with an increased risk of pouch-related complications (P = 0.01). The presence of submucosal oedema was also a significant risk factor (P = 0.03). CONCLUSION The extension of inflammation into the muscularis propria appears to predict pouch-related complications following restorative proctocolectomy for UC or IC.
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Affiliation(s)
- K-K Tan
- Department of Colorectal Surgery, Royal Prince Alfred Hospital, Sydney, Australia; Surgical Outcomes Research Centre, Central Sydney Area Health Service and University of Sydney, Sydney, Australia
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Arjunan V, Senthilkumari S, Ravindran P, Mohan S. Synthesis, FTIR and FT-Raman spectral analysis and structure–activity relations of N-(4-bromophenyl)-2,2-dichloroacetamide by DFT studies. J Mol Struct 2014. [DOI: 10.1016/j.molstruc.2014.01.091] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Ravindran P, Ansari N, Young CJ, Solomon MJ. Definitive surgical closure of enterocutaneous fistula: outcome and factors predictive of increased postoperative morbidity. Colorectal Dis 2014; 16:209-18. [PMID: 24521276 DOI: 10.1111/codi.12473] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/26/2013] [Accepted: 08/16/2013] [Indexed: 12/12/2022]
Abstract
AIM Enterocutaneous fistula (ECF) presents a complex management problem with significant mortality and morbidity. The aim of this study was to assess the outcome of patients undergoing surgical cure for ECF and to predict factors that might relate to increased postoperative morbidity. METHOD Medical records of all patients who underwent definitive surgery for cure of an ECF within our colorectal surgery unit between 2000 and 2010 were reviewed. RESULTS Forty-one patients (18 male) were identified, in whom 44 definitive procedures were performed. The median age was 54 (17-81) years. The median postoperative length of stay in hospital was 14 (2-213) days. Half (50%) of the ECFs occurred as a postoperative complication followed by spontaneous fistulation in Crohn's disease (36%). The interval to definitive surgery was influenced by the aetiology of the fistula. The median time to surgery after formation of postoperative fistula was 240 days (7.9 months). There was no 30-day postoperative mortality. There were two (4.5%) recurrences at 3 months. Thirty-eight (86%) patients suffered postoperative morbidity as defined by the Clavien-Dindo classification. High-grade morbidity occurred in 32% of patients. On univariate analysis, factors identified as being significantly associated with high-grade morbidity included a fistula output of > 500 ml/day (P = 0.004) in patients with postoperative ECF, malnutrition at presentation (P = 0.04) and a serum albumin value of < 30 g/l (P = 0.02) in patients with spontaneous ECF due to Crohn's disease. CONCLUSION The majority of persistent complex ECFs can be cured surgically with low mortality and recurrence in a multidisciplinary setting. Postoperative morbidity, however, remains a significant burden.
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Affiliation(s)
- P Ravindran
- Surgical Outcomes Research Centre (SOURCE), Royal Prince Alfred Hospital, University of Sydney, Sydney, New South Wales, Australia; Department of Colorectal Surgery, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
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Arjunan V, Raj A, Ravindran P, Mohan S. Structure-activity relations of 2-(methylthio)benzimidazole by FTIR, FT-Raman, NMR, DFT and conceptual DFT methods. Spectrochim Acta A Mol Biomol Spectrosc 2014; 118:951-965. [PMID: 24184580 DOI: 10.1016/j.saa.2013.09.100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Revised: 09/11/2013] [Accepted: 09/26/2013] [Indexed: 06/02/2023]
Abstract
The vibrational fundamental modes of 2-(methylthio)benzimidazole (2MTBI) have been analysed by combining FTIR, FT-Raman and quantum chemical calculations. The structural parameters of the compound are determined from the optimised geometry by B3LYP with 6-31G(∗∗), 6-311++G(∗∗) and cc-pVTZ basis sets and giving energies, harmonic vibrational frequencies, depolarisation ratios, IR intensities and Raman activities. (1)H and (13)C NMR spectra have been analysed and (1)H and (13)C nuclear magnetic resonance chemical shifts are calculated using the gauge independent atomic orbital (GIAO) method. The structure-activity relationship of the compound is also investigated by conceptual DFT methods. The chemical reactivity and site selectivity of the molecule has been determined with the help of global and local reactivity descriptors.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605 008, India.
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Arjunan V, Govindaraja ST, Ravindran P, Mohan S. Exploring the structure-activity relations of N-carbethoxyphthalimide by combining FTIR, FT-Raman and NMR spectroscopy with DFT electronic structure method. Spectrochim Acta A Mol Biomol Spectrosc 2013; 120:473-488. [PMID: 24211807 DOI: 10.1016/j.saa.2013.10.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Revised: 09/29/2013] [Accepted: 10/02/2013] [Indexed: 06/02/2023]
Abstract
The complete vibrational assignment and analysis of N-carbethoxyphthalimide were carried out using the experimental FTIR and FT-Raman data in the range 4000-450 and 4000-100 cm(-1), respectively along with quantum chemical studies of the compound using DFT-B3LYP gradient calculations employing the 6-31G**, 6-311++G** and cc-pVDZ basis sets. The 1H (400 MHz; CDCl3) and 13C (100 MHz;CDCl3) nuclear magnetic resonance (NMR) spectra were also recorded. Due to the partial ionic nature of the carbonyl group, the carbon atoms C1 and C3 in NCEP show downfield effect and the corresponding observed chemical shift of both are observed at 163.76 ppm and the carbon atom C16 in the carbethoxy group also give signal in the downfield at 148.45 ppm. The active sites are determined by molecular electrostatic potential. The possible electronic transitions are determined by HOMO and LUMO orbital shapes and their energies. The structure-chemical reactivity relations of the compound were determined through chemical potential, global hardness, global softness, electronegativity, electrophilicity and local reactivity descriptors by conceptual DFT methods.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605 008, India.
| | | | - P Ravindran
- Department of Chemistry, Mahatma Gandhi Govt. Arts College, Mahe 673 310, India
| | - S Mohan
- School of Sciences and Humanities, Vel Tech University, Avadi, Chennai 600 062, India
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Ravindran P, Kumar S, Peace T. SU-E-J-162: Evaluation of the Geometric Accuracy and Image Quality of KV CBCT Based IGRT System. Med Phys 2013. [DOI: 10.1118/1.4814374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Ravindran P, Kumar S, Sharma S, John S. SU-E-J-161: In Vivo Dose Measurement During IGRT with KV Cone Beam CT. Med Phys 2013. [DOI: 10.1118/1.4814373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Arjunan V, Ravindran P, Santhanam R, Raj A, Mohan S. A comparative study on vibrational, conformational and electronic structure of 1,2-dimethyl-5-nitroimidazole and 2-methyl-5-nitroimidazole. Spectrochim Acta A Mol Biomol Spectrosc 2012; 97:176-188. [PMID: 22763322 DOI: 10.1016/j.saa.2012.05.072] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Revised: 05/12/2012] [Accepted: 05/29/2012] [Indexed: 06/01/2023]
Abstract
The FTIR and FT-Raman spectra of 1,2-dimethyl-5-nitroimidazole and 2-methyl-5-nitroimidazole have been recorded in the regions 4000-400 and 4000-100 cm(-1), respectively. The conformational analyses were performed and the energies of the different possible conformers were determined. The geometry of different conformers of the compounds were optimised with B3LYP and B3PW91 methods using 6-311++G and aug-cc-pVTZ basis sets to characterise all stationary points as minima. The optimised structural parameters of the most stable conformer were used in the vibrational frequency calculations. The Raman activities were also determined with B3LYP method using 6-311++G basis sets. The force constants obtained from the B3LYP/6-311++G method have been utilised in the normal coordinate analysis. The temperature dependence of the thermodynamic properties heat capacity at constant pressure (C(p)), entropy (S) and enthalpy change (ΔH(0→T)) for both the compounds were also determined by B3LYP/6-311++G method. The total electron density and MESP surfaces of the molecules were constructed by NBO analysis using B3LYP/6-311++G method to display electrostatic potential (electron+nuclei) distribution, molecular shape, size, and dipole moments of the molecule. The electronic properties HOMO and LUMO energies were measured. The influences of nitro and methyl groups on the skeletal modes have been investigated.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605 008, India.
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Roure C, Khalakdina A, Ungchusak K, Yulizar M, Ravindran P, Watson J, Pinto A. Panel 2.2: Surveillance, Early Warning Alert, and Response: Communicable and Vector-Borne Diseases. Prehosp Disaster Med 2012; 20:399-403. [PMID: 16496622 DOI: 10.1017/s1049023x00002971] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
AbstractThis is a summary of the presentations and discussion of Surveillance, Early Warning Alert and Response at the Conference, Health Aspects of the Tsunami Disaster in Asia, convened by the World Health Organization (WHO)in Phuket, Thailand, 04–06 May 2005. The topics discussed included issues related to the surveillance, early warning alert, and response to communicable and vector-borne diseases as pertaining to the responses to the damage created bythe Tsunami. It is presented in the following major sections: (1) key questions; (2) needs assessment; (3) coordination(4) gap filling; and (5) capacity building. The key questions section is presented in six sub-sections: (1) communicable diseases; (2) early warning; (3) laboratory capacity and referral networking; (4) coordination of disease surveillance, early warning, and response; (5) health infrastructure rebuilding; and (6) using existing national surveillance plans toenhance disease surveillance and early warning systems.
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Affiliation(s)
- Collette Roure
- Prime Minister's Office, Tsunami Relief Coordination Task Force, France
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Singh PK, Ofrin R, Ravindran P, Paturussi I, Yasir I, Aung T, Kahandailyanage HAP, Kunaratanapruk S. Session 1.2: National Health Perspectives of the Tsunami Crisis. Prehosp Disaster Med 2012; 20:382-4. [PMID: 16496617 DOI: 10.1017/s1049023x00002922] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
AbstractThis is a summary of the presentations and discussion of Session 1.2 of the Conference, Health Aspects of the Tsunami Disaster in Asia, convened by the World Health Organization (WHO) in Phuket, Thailand, 04–06 May 2005. The topics discussed included issues related national health perspectives as pertaining to the responses to the damage created by the Tsunami. It is presented in the following major sections: (1) key questions; (2) discussion; (3) what was done well?; (4) what could have been done better?; and (5) what can be done to prepare for the future?.
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Arjunan V, Ravindran P, Balakrishnan K, Santhanam R, Mohan S. Combined spectroscopic and DFT studies on 2-chloro-4-nitrotoluene and 4-chloro-2-nitrotoluene. J Mol Struct 2012. [DOI: 10.1016/j.molstruc.2012.02.043] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Sebastian P, Balakrishnan R, Das S, Isiah R, Singh R, Ravindran P, John S. Radiotherapy for Pituitary Adenomas: A Single Institutional Experience. Int J Radiat Oncol Biol Phys 2011. [DOI: 10.1016/j.ijrobp.2011.06.1764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Vajeeston P, Ravindran P, Fjellvåg H. Phonon, IR, and Raman Spectra, NMR Parameters, and Elastic Constant Calculations for AlH3 Polymorphs. J Phys Chem A 2011; 115:10708-19. [DOI: 10.1021/jp2011342] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- P. Vajeeston
- Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Box 1033 Blindern N-0315, Oslo, Norway
| | - P. Ravindran
- Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Box 1033 Blindern N-0315, Oslo, Norway
| | - H. Fjellvåg
- Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Box 1033 Blindern N-0315, Oslo, Norway
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Arjunan V, Kalaivani M, Ravindran P, Mohan S. Structural, vibrational and quantum chemical investigations on 5-chloro-2-hydroxybenzamide and 5-chloro-2-hydroxybenzoic acid. Spectrochim Acta A Mol Biomol Spectrosc 2011; 79:1886-1895. [PMID: 21689976 DOI: 10.1016/j.saa.2011.05.082] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Revised: 05/21/2011] [Accepted: 05/25/2011] [Indexed: 05/30/2023]
Abstract
The Fourier transform infrared (FTIR) and FT-Raman spectra of 5-chloro-2-hydroxybenzamide (5CBA) and 5-chloro-2-hydroxybenzoic acid (5C2HBA) have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The complete vibrational fundamental modes of the compounds were assigned and analysed using the observed FTIR and FT-Raman data. The vibrational frequencies determined experimentally were compared with the theoretical wavenumbers calculated from ab initio HF and DFT-B3LYP gradient methods employing 6-31G** and 6-311++G** basis sets. The effect of halogen, hydroxyl groups and hydrogen bonding on the characteristic frequencies of the -COOH and -CONH2 group frequencies have been investigated. In 5CBA and 5C2HBA intramolecular hydrogen bond between a hydroxyl group and CO group makes a six membered ring, which causes the O⋯H interaction onto the resonance of the benzene ring. Comparison of the positions of the ν(OH) bands shows the ν(OH) band of 5CBA is located at considerably higher frequency which confirms a weaker hydrogen bond than in 5C2HBA.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605 008, India.
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32
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Horikawa Y, Tsuchiya N, Yuasa K, Narita S, Saito M, Takayama K, Nara T, Tsuruta H, Obara T, Numakura K, Satoh S, Habuchi T, Hu X, Guo J, Lin Z, Sun L, Xu Z, Cang C, Wang G, Kanda T, Sakamoto K, Matsuki A, Ohashi R, Hirota S, Fujimori Y, Matsuda Y, Yajima K, Kosugi S, Hatakeyama K, Kitahara K, Watanabe M, Nakazono S, Wada N, Kakizaki H, Li J, Gong FJ, Sun PN, Shen L, Li Q, Li N, Qiu M, Liu J, Yi C, Luo D, Li Z, Gou H, Yang Y, Cao D, Shen Y, Wang X, Xu F, Bi F, Li Q, Zhang X, Li N, Wei W, Luo HY, Wang ZQ, Wang FH, Qiu MZ, Teng KY, Ruan DY, He YJ, Li YH, Xu RH, Matsusaka S, Mizunuma N, Suenaga M, Shinozaki E, Mishima Y, Terui Y, Hatake K, Nara E, Kodaira M, Mishima Y, Yokoyama M, Saotome T, Terui Y, Takahashi S, Hatake K, Nishimura N, Nakano K, Kodaira M, Ueda K, Yamada S, Mishima Y, Yokoyama M, Saotome T, Takahashi S, Terui Y, Hatake K, Nozawa M, Mochida Y, Nishigaki K, Nagae S, Uemura H, Oh SY, Jeong CY, Hong SC, Lee WS, Kim HG, Lee GW, Hwang IG, Jang JS, Kwon HC, Kang JH, Ozaka M, Ogura M, Matsusaka S, Shinozaki E, Suenaga M, Chin K, Mizunuma N, Hatake K, Pua PF, Ganzon D, Chan V, Sailaja K, Vishnupriya S, Raghunadharao D, Markandeya G, Reddy PRK, Reddanna P, Praveen D, Sakamoto K, Kanda T, Matsuki A, Takano T, Hanyu T, Yajima K, Kosugi S, Hirota S, Hatakeyama K, Shigekawa T, Ijichi N, Takayama S, Tsuda H, Ikeda K, Horie K, Osaki A, Saeki T, Inoue S, Subhashini J, Rajesh B, Rajesh I, Ravindran P, Takagi K, Chin K, Oba M, Kuboki Y, Ichimura T, Oto M, Kawazoe Y, Watanabe T, Ozaka M, Ogura M, Suenaga M, Shinozaki E, Matsusaka S, Mizunuma N, Hatake K, Ueda K, Saotome T, Yamada S, Nishimura N, Nara E, Nakano K, Kodaira M, Katsube A, Mishima Y, Terui Y, Yokoyama M, Takahashi S, Hatake K, Yao X, Yang Q, Li C, Diao L, Chen X, Yu Z, Zuo W, Wang Y, He Y, Zhang X, Cai S, Wang Z, Xu J, Zhan W, Zhang YF, Misumi M, Takeuchi H, Nakamiya N, Shigekawa T, Matsuura K, Fujiuchi N, Osaki A, Saeki T. CLINICAL OUTCOMES. Jpn J Clin Oncol 2011. [DOI: 10.1093/jjco/hyq254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Abstract
Phase stability and chemical bonding of beta-NaBH4 and beta-KBH4 derived nano-structures and possible low energy surfaces of them from thin film geometry have been investigated using ab initio projected augmented plane wave method. Structural optimizations based on total energy calculations predicted that, for beta-NaBH4 and beta-KBH4 phases, the (011) and (101) surfaces are more stable among the possible low energy surfaces. The predicted critical size of the nano-cluster for beta-NaBH4 and beta-KBH4 is 1.35 and 1.8 nm, respectively. The corresponding critical diameter for the nano-whisker is 2.6 and 2.8 nm respectively for beta-NaBH4 and beta-KBH4. Structural optimization based on total energy calculations show that the bond distances in the surfaces of nano-whisker are found to be higher than that in the bulk material and the calculated H site energies and bond overlap population analysis suggesting that it is considerably easier to remove hydrogen from the surface of the clusters and nano-whiskers than that from the bulk crystals.
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Affiliation(s)
- P Vajeeston
- Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Box 1033 Blindern, N-0315 Oslo, Norway
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Arjunan V, Ravindran P, Rani T, Mohan S. FTIR, FT-Raman, FT-NMR, ab initio and DFT electronic structure investigation on 8-chloroquinoline and 8-nitroquinoline. J Mol Struct 2011. [DOI: 10.1016/j.molstruc.2010.12.032] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Arjunan V, Saravanan I, Ravindran P, Mohan S. FTIR, FT-Raman, ab initio and density functional studies on 4-methyl-1,3-dioxolan-2-one and 4,5-dichloro-1,3-dioxolan-2-one. Spectrochim Acta A Mol Biomol Spectrosc 2010; 77:28-35. [PMID: 20605517 DOI: 10.1016/j.saa.2010.04.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2010] [Revised: 04/11/2010] [Accepted: 04/14/2010] [Indexed: 05/29/2023]
Abstract
The Fourier transform infrared (FTIR) and FT-Raman spectra of 4-methyl-1,3-dioxolan-2-one and 4,5-dichloro-1,3-dioxolan-2-one have been recorded in the range 3700-400 and 3700-100 cm(-1), respectively. The complete vibrational assignment and analysis of the fundamental modes of the compounds were carried out using the observed FTIR and FT-Raman data. The vibrational frequencies determined experimentally were compared with those obtained theoretically from ab initio HF and DFT-B3LYP gradient calculations employing 6-311++G** and cc-pVTZ basis sets for the optimised geometries of the compounds. The geometries and normal modes of vibration obtained from the HF and DFT methods are in good agreement with the experimental data. The normal coordinate analysis was also carried out with ab initio force fields utilising Wilson's FG matrix method. The interactions of the skeletal vibrational modes were investigated.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Lawspet, Puducherry 605 008, India.
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Ravindran P, Narmatha M. SU-GG-T-343: Small Photon Field Dosimetry with Gel. Med Phys 2010. [DOI: 10.1118/1.3468740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Ravindran P, Balukrishna S, Viswanathan P. SU-GG-T-179: Dosimetric Analysis of Simultaneous Integrated Boost with Step and Shoot IMRT. Med Phys 2010. [DOI: 10.1118/1.3468569] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Ravindran P, Sloboda R. SU-GG-T-87: Seed Cloud Volume as Surrogate for Prostate Volume for Dosimetry of 125I Permanent Brachytherapy. Med Phys 2010. [DOI: 10.1118/1.3468475] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Abstract
The ground-state structure, equilibrium structural parameters, electronic structure, and thermodynamical properties of MCaH(3) (M=Li, Na, K, Rb, and Cs) phases have been investigated. From the 104 structural models used as inputs for structural optimization calculations, the ground-state crystal structures of MCaH(3) phases have been predicted. At ambient condition, LiCaH(3), NaCaH(3), and KCaH(3) crystallize in hexagonal, monoclinic, and orthorhombic structures, respectively. The remaining phases RbCaH(3) and CsCaH(3) crystallize in a cubic structure. The calculated phonon spectra indicate that all the predicted phases are dynamically stable. The formation energy for the MCaH(3) phases have been calculated along different reaction pathways. The electronic structures reveal that all these phases are insulators with an estimated band gap varying between 2.5 and 3.3 eV.
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Affiliation(s)
- P Vajeeston
- Department of Chemistry, Center for Materials Sciences and Nanotechnology, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, Norway.
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Karazhanov SZ, Ravindran P, Vajeeston P, Ulyashin AG, Fjellvåg H, Svensson BG. Phase stability and pressure-induced structural transitions at zero temperature in ZnSiO(3) and Zn(2)SiO(4). J Phys Condens Matter 2009; 21:485801. [PMID: 21832530 DOI: 10.1088/0953-8984/21/48/485801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Using density functional total energy calculations the structural phase stability and pressure-induced structural transition in different polymorphs of ZnSiO(3) and Zn(2)SiO(4) have been studied. Among the considered monoclinic phase with space groups (P 2(1)/c) and (C 2/c), rhombohedral [Formula: see text] and orthorhombic (Pbca) modifications the monoclinic phase (P 2(1)/c) of ZnSiO(3) is found to be the most stable one. At high pressure monoclinic ZnSiO(3) (C 2/c) can co-exist with orthorhombic (Pbca) modification. Differences in equilibrium volume and total energy of these two polymorphs are very small, which indicates that it is relatively easier to transform between these two phases by temperature, pressure or chemical composition. It can also explain the experimentally established result of metastability of the orthorhombic phase under all conditions. The following sequence of pressure-induced structural phase transitions is found for ZnSiO(3) polymorphs: monoclinic [Formula: see text] monoclinic [Formula: see text] rhombohedral [Formula: see text]. Among the rhombohedral ([Formula: see text]), tetragonal [Formula: see text], orthorhombic (Pbca), orthorhombic (Imma), cubic [Formula: see text] and orthorhombic (Pbnm) modifications of Zn(2)SiO(4), the rhombohedral phase is found to be the ground state. For this chemical composition of zinc silicate the following sequence of structural phase transitions is found: rhombohedral [Formula: see text] tetragonal [Formula: see text] orthorhombic [Formula: see text] orthorhombic (Imma) [Formula: see text] cubic [Formula: see text] orthorhombic (Pbnm). Based on the analogy of crystal structures of magnesium and zinc silicates and using the lattice and positional parameters of Mg(2)SiO(4) as input, structural properties of spinel Zn(2)SiO(4) have also been studied.
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Affiliation(s)
- S Zh Karazhanov
- Centre for Material Science and Nanotechnology, Department of Chemistry, University of Oslo, PO Box 1033 Blindern, N-0315 Oslo, Norway. Institute for Energy Technology, PO Box 40, N-2027 Kjeller, Norway. Physical-Technical Institute, 2B Mavlyanov Street, Tashkent 700084, Uzbekistan
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Arjunan V, Mohan S, Balamourougane PS, Ravindran P. Quantum chemical and spectroscopic investigations of 5-aminoquinoline. Spectrochim Acta A Mol Biomol Spectrosc 2009; 74:1215-1223. [PMID: 19854675 DOI: 10.1016/j.saa.2009.09.039] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2009] [Revised: 09/05/2009] [Accepted: 09/24/2009] [Indexed: 05/28/2023]
Abstract
The Fourier transform infrared (FTIR) and FT-Raman spectra of 5-aminoquinoline (5AQ) have been recorded in the range 4000-400 and 3500-100 cm(-1), respectively. The complete vibrational assignment and analysis of the fundamental modes of the compounds were carried out using the observed FTIR and FT-Raman data. (1)H and (13)C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by using the gauge independent atomic orbital (GIAO) method. UV-vis spectrum of the compound was recorded and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The geometric parameters, chemical shifts and absorption wavelengths were compared with the experimental data of the molecule. The vibrational frequencies which were determined experimentally are compared with those obtained theoretically from ab initio HF and DFT-B3LYP gradient calculations employing the 6-31G** and 6-311++G** basis sets for optimized geometries of the compound. The interactions of NH-pi and the influence of amino group on the skeletal modes are investigated.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605 008, India.
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Arjunan V, Ravindran P, Subhalakshmi K, Mohan S. Synthesis, structural, vibrational and quantum chemical investigations of N-(2-methylphenyl)-2,2-dichloroacetamide and N-(4-methylphenyl)-2,2-dichloroacetamide. Spectrochim Acta A Mol Biomol Spectrosc 2009; 74:607-616. [PMID: 19647479 DOI: 10.1016/j.saa.2009.07.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2009] [Revised: 06/25/2009] [Accepted: 07/07/2009] [Indexed: 05/28/2023]
Abstract
N-(2-Methylphenyl)-2,2-dichloroacetamide (2MPA) and N-(4-methylphenyl)-2,2-dichloroacetamide (4MPA) of the configuration X(y)C(6)H(5-y)-NHCO-CHCl(2) (where, X=CH(3) and y=1) were synthesised and an extensive spectroscopic investigations have been carried out by recording the Fourier transform infrared (FTIR) and FT-Raman spectra and subjecting them to normal co-ordinate analysis, in an effort to provide mixing of the fundamental modes with the help of potential energy distribution (PED). The ab initio and DFT studies were carried out with 6-311++G(d,p) basis set to determine the structural, thermodynamical and vibrational characteristics of the compounds and also to understand the steric influence of methyl group on the characteristic frequencies of amide (-CONH-) group.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry - 605 008, India.
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Arjunan V, Saravanan I, Ravindran P, Mohan S. Structural, vibrational and DFT studies on 2-chloro-1H-isoindole-1,3(2H)-dione and 2-methyl-1H-isoindole-1,3(2H)-dione. Spectrochim Acta A Mol Biomol Spectrosc 2009; 74:642-649. [PMID: 19660980 DOI: 10.1016/j.saa.2009.07.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 07/02/2009] [Accepted: 07/07/2009] [Indexed: 05/28/2023]
Abstract
The Fourier transform infrared (FTIR) and FT-Raman spectra of 2-chloro-1H-isoindole-1,3(2H)-dione and 2-methyl-1H-isoindole-1,3(2H)-dione have been measured in the range of 4000-400 and 4000-100 cm(-1), respectively. Complete vibrational assignment and analysis of the fundamental modes of the compounds were performed using the observed FTIR and FT-Raman data. The geometry was optimised without any symmetry constraints using the DFT/B3LYP method with 6-31G(d,p) and 6-311++G(d,p) basis sets. The vibrational frequencies determined experimentally are compared with those obtained theoretically from DFT gradient calculations employing the B3LYP/6-31G(d,p) and B3LYP/6-311++G(d,p) methods for the optimised geometry of the compounds. The structural parameters and normal modes of vibration obtained from DFT method are in good agreement with the experimental data. The force fields obtained from DFT method were utilised and the potential energy distributions of all the fundamental vibrations of the compounds were calculated.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Puducherry 605008, India.
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Arjunan V, Saravanan I, Ravindran P, Mohan S. Ab initio, density functional theory and structural studies of 4-amino-2-methylquinoline. Spectrochim Acta A Mol Biomol Spectrosc 2009; 74:375-384. [PMID: 19581121 DOI: 10.1016/j.saa.2009.06.028] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2008] [Revised: 05/25/2009] [Accepted: 06/08/2009] [Indexed: 05/28/2023]
Abstract
The Fourier transform infrared (FTIR) and FT-Raman spectra of 4-amino-2-methylquinoline (AMQ) have been recorded in the range 4000-400 and 4000-100 cm(-1), respectively. The experimental vibrational frequency was compared with the wavenumbers obtained theoretically by ab initio HF and DFT-B3LYP gradient calculations employing the standard 6-31 G** and high level 6-311 ++G** basis sets for optimised geometry of the compound. The complete vibrational assignment and analysis of the fundamental modes of the compounds were carried out using the experimental FTIR and FT-Raman data, and quantum mechanical studies. The geometry and normal modes of vibration obtained from the HF and DFT methods are in good agreement with the experimental data. The potential energy distribution of the fundamental modes was calculated with ab initio force fields utilising Wilson's FG matrix method. The NH-pi interactions and the influence of amino and methyl groups on the skeletal modes are investigated.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Lawspet, Puducherry 605008, India.
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Abstract
The phase stability and electronic structure of alpha- LiBH(4)-derived nanostructures and possible low energy surfaces of thin films have been investigated using the ab initio projected augmented plane wave method. Structural optimizations based on total energy calculations predicted that, for the alpha- LiBH(4) phase, the (010) surface is the most stable of the possible low-energy surfaces. The predicted critical sizes of the nano-cluster and nano-whisker for alpha- LiBH(4) are 1.75 and 1.5 nm, respectively. Similarly, the bond distances in the surfaces of a nano-whisker are found to be higher than that in the bulk material. The calculated hydrogen site energies suggest that it is relatively easier to remove hydrogen from the surface of the clusters and nano-whiskers than from bulk crystals.
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Affiliation(s)
- P Vajeeston
- Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Box 1033 Blindern, N-0315, Oslo, Norway.
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Arjunan V, Mohan S, Ravindran P, Mythili CV. Vibrational spectroscopic investigations, ab initio and DFT studies on 7-bromo-5-chloro-8-hydroxyquinoline. Spectrochim Acta A Mol Biomol Spectrosc 2009; 72:783-788. [PMID: 19112045 DOI: 10.1016/j.saa.2008.11.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2008] [Revised: 11/10/2008] [Accepted: 11/15/2008] [Indexed: 05/27/2023]
Abstract
The Fourier transform infrared (FTIR) and FT-Raman spectra of 7-bromo-5-chloro-8-hydroxyquinoline (BCHQ) have been measured in the range 4000-400 and 4000-100cm(-1), respectively. Complete vibrational assignment and analysis of the fundamental modes of the compound were carried out using the observed FTIR and FT-Raman data. The geometry was optimised without any symmetry constrains using the DFT/B3LYP and HF methods with 6-31G** basis set. The vibrational frequencies which were determined experimentally are compared with those obtained theoretically from ab initio HF and density functional theory (DFT) gradient calculations employing the HF/6-31G** and B3LYP/6-31G** methods for the optimised geometry of the compound. The structural parameters and normal modes of vibration obtained from HF and DFT methods are in good agreement with the experimental data. Normal coordinate analysis was also carried out with ab initio force fields utilising Wilson's FG matrix method.
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Affiliation(s)
- V Arjunan
- Department of Chemistry, Kanchi Mamunivar Centre for Post-Graduate Studies, Lawspet, Puducherry, India.
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Peace T, Subramanian B, Ravindran P. An experimental study on using a diagnostic computed radiography system as a quality assurance tool in radiotherapy. Australas Phys Eng Sci Med 2008; 31:226-34. [PMID: 18946982 DOI: 10.1007/bf03179349] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The advent of improved digital imaging modalities in diagnostic and therapy is fast making conventional films a nonexistent entity. However, several radiotherapy centers still persist with film for performing quality assurance (QA) tests. This paper investigates the feasibility of using a diagnostic computed radiography (CR) system as a QA tool in radiotherapy. QA tests such as light field congruence, field size verification, determination of radiation isocentre size, multileaf collimator (MLC) check and determination of isocentric shift for stereotactic radiosurgery (SRS) were performed and compared with film. The maximum variation observed between CR and film was 0.4 mm for field size verification, -0.13 mm for the radiation isocentre size check, 0.77 for MLC check and -0.1 mm for isocentric shift using the Winston Lutz test tool for SRS QA. From these results obtained with the CR it is concluded that a diagnostic CR system can be an excellent cost-effective digital alternative to therapy film as a tool for QA in radiotherapy.
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Affiliation(s)
- T Peace
- Department of Radiotherapy, Christian Medical College, Vellore, India.
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Vidya R, Ravindran P, Knizek K, Kjekshus A, Fjellvåg H. Density functional theory studies of spin, charge, and orbital ordering in YBaT2O5 (T = Mn, Fe, Co). Inorg Chem 2008; 47:6608-20. [PMID: 18611004 DOI: 10.1021/ic702025c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Spin, charge, and orbital orderings are influenced by electron/hole doping, cation radii, oxygen stoichiometry, temperature, magnetic field, and so on. In order to understand the role of electron/hole doping, we have studied variations in spin, charge, and orbital ordering in terms of d-band filling for YBaT 2O 5 (T = Mn, Fe, Co). The calculations were performed using density functional theory as implemented in the full-potential linearized augmented-plane-wave method. We have carried out calculations for nonmagnetic, ferromagnetic, and antiferromagnetic configurations. A ferrimagnetic ground state was established for YBaMn 2O 5, whereas YBaFe 2O 5 and YBaCo 2O 5 have antiferromagnetic ground states; all of these results are in agreement with experimental findings. The effects of spin-orbit coupling, the Hubbard U parameter, and orbital polarization on the magnetic properties were also analyzed. The electronic band characteristics were analyzed using total as well as site- and orbital-projected densities of states. Inclusion of spin-orbit coupling and Coulomb correlation effects in the calculations was found to be important in order to reproduce the experimentally established semiconducting behaviors of YBaFe 2O 5 and YBaCo 2O 5. In order to quantify the charges at each atomic site, we made use of the Bader "atom-in-molecule" concept and Born effective-charge (BEC) analyses. The structural optimizations and BEC tensor calculations were performed using the VASP-PAW method. The different types of charge and orbital orderings in these compounds were visualized using the energy-projected density matrices of the d electrons. Substantial differences in ordering patterns with respect to d-band filling emerged. Ordering of the d z (2) orbital of Mn in YBaMn 2O 5 gave rise to G-type ferrimagnetic spin ordering along the c direction and checkerboard-type charge ordering, whereas ordering of the d x (2) - y (2) orbital of Fe in YBaFe 2O 5 caused Wollan-Koehler G-type antiferromagnetic spin ordering along the b direction and stripe-type charge ordering. Similarly, a complex pattern of orbital ordering in YBaCo 2O 5 activated spin and charge orderings similar to those in YBaFe 2O 5.
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Affiliation(s)
- R Vidya
- Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Box 1033 Blindern, N-0315 Oslo, Norway.
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Abstract
The phase stability, chemical bonding, and electronic structure of MgH(2) nanowires and possible low energy surfaces of α-MgH(2) thin films have been investigated using the ab initio projected augmented plane-wave method. Structural optimizations based on total energy calculations predicted that, for the α-MgH(2) phase, the (101) surface is more stable among the possible low energy surfaces. The electronic structure study reveals that the nanowires also have nonmetallic character similar to that of the bulk and thin film phases. Bonding analysis shows that the character of chemical bonding in nanowires has been considerably changed compared with that in bulk phases. Similarly, the bond distances in the surfaces of nanowires are found to be higher than in the bulk material, suggesting that it is possible to remove hydrogen from the nanowires considerably more easily than from bulk crystals.
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Affiliation(s)
- P Vajeeston
- Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Box 1033 Blindern, N-0315, Oslo, Norway
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Kron T, Cheung KY, Dai J, Ravindran P, Soejoko D, Inamura K, Song JY, Bold L, Srivastava R, Rodriguez L, Wong TJ, Kumara A, Lee CC, Krisanachinda A, Nguyen XC, Ng KH. Medical physics aspects of cancer care in the Asia Pacific region. Biomed Imaging Interv J 2008; 4:e33. [PMID: 21611001 PMCID: PMC3097731 DOI: 10.2349/biij.4.3.e33] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Accepted: 06/17/2008] [Indexed: 11/17/2022] Open
Abstract
Medical physics plays an essential role in modern medicine. This is particularly evident in cancer care where medical physicists are involved in radiotherapy treatment planning and quality assurance as well as in imaging and radiation protection. Due to the large variety of tasks and interests, medical physics is often subdivided into specialties such as radiology, nuclear medicine and radiation oncology medical physics. However, even within their specialty, the role of radiation oncology medical physicists (ROMPs) is diverse and varies between different societies. Therefore, a questionnaire was sent to leading medical physicists in most countries/areas in the Asia/Pacific region to determine the education, role and status of medical physicists.Answers were received from 17 countries/areas representing nearly 2800 radiation oncology medical physicists. There was general agreement that medical physicists should have both academic (typically at MSc level) and clinical (typically at least 2 years) training. ROMPs spent most of their time working in radiotherapy treatment planning (average 17 hours per week); however radiation protection and engineering tasks were also common. Typically, only physicists in large centres are involved in research and teaching. Most respondents thought that the workload of physicists was high, with more than 500 patients per year per physicist, less than one ROMP per two oncologists being the norm, and on average, one megavoltage treatment unit per medical physicist.There was also a clear indication of increased complexity of technology in the region with many countries/areas reporting to have installed helical tomotherapy, IMRT (Intensity Modulated Radiation Therapy), IGRT (Image Guided Radiation Therapy), Gamma-knife and Cyber-knife units. This and the continued workload from brachytherapy will require growing expertise and numbers in the medical physics workforce. Addressing these needs will be an important challenge for the future.
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Affiliation(s)
- T Kron
- Physical Sciences, Peter MacCallum Cancer Centre, and RMIT University, Melbourne, Australia
| | - KY Cheung
- Department of Clinical Oncology, Prince of Wales Hospital, Hong Kong, China
| | - J Dai
- Cancer Institute (Hospital), Chinese Academy of Medical Sciences, China
| | - P Ravindran
- Department of Radiation Oncology, Christian Medical College, Vellore, India
| | - D Soejoko
- Physics Department, University of Indonesia, Jakarta, Indonesia
| | - K Inamura
- Dept of Radiology & Medical Engineering, Kansai University of International Studies, Hyogo, Japan
| | - JY Song
- Department of Radiation Oncology, Chonnam National University Hospital, Republic of Korea
| | - L Bold
- Radiotherapy Department, National Cancer Center, Ulaanbaatar, Mongolia
| | - R Srivastava
- B.P.Koirala Memorial Cancer Hospital, Bharatpur, Chitwan, Nepal
| | - L Rodriguez
- Department of Radiation Oncology, Jose R. Reyes Memorial Medical Center, Manila, Philippines
| | - TJ Wong
- Department of Therapeutic Radiology, National Cancer Centre, Singapore
| | - A Kumara
- Division of Medical Physics, National Cancer Institute, Sri Lanka
| | - CC Lee
- Department of Medical Imaging and Radiological Sciences, Chang Gung University, Taiwan
| | - A Krisanachinda
- Department of Radiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - XC Nguyen
- K Hospital, National Cancer Institute, Hanoi, Vietnam
| | - KH Ng
- Department of Biomedical Imaging, University of Malaya, and Medical Physics Unit, University of Malaya Medical Centre, Kuala Lumpur, Malaysia
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