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Elango M, Subramanian V, Rahalkar AP, Gadre SR, Sathyamurthy N. Structure, energetics, and reactivity of boric acid nanotubes: a molecular tailoring approach. J Phys Chem A 2008; 112:7699-704. [PMID: 18652434 DOI: 10.1021/jp802723e] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Cardinality guided molecular tailoring approach (CG-MTA) [Ganesh et al. J. Chem. Phys. 2006, 125, 104019] has been effectively employed to perform ab initio calculations for large molecular clusters of boric acid. It is evident from the results that boric acid forms nanotubes, structurally similar to carbon nanotubes, with the help of an extensive hydrogen-bonding (H-bonding) network. Planar rosette-shaped hexamer of boric acid is the smallest repeating unit in such nanotubes. The stability of these tubes increases due to enhancement in the number of H-bonding interactions as the diameter increases. An analysis of molecular electrostatic potential (MESP) of these systems provides interesting features regarding the reactivity of these tubes. It is predicted that due to alternate negative and positive potentials on O and B atoms, respectively, boric acid nanotubes will interact favorably with polar systems such as water and can also form multiwalled tubes.
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Affiliation(s)
- M Elango
- Chemical Laboratory, Central Leather Research Institute, Council of Scientific and Industrial Research, Adyar, Chennai, India 600 020
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152
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Raman SS, Vijayaraj R, Parthasarathi R, Subramanian V. Helix forming tendency of valine substituted poly-alanine: a molecular dynamics investigation. J Phys Chem B 2008; 112:9100-4. [PMID: 18597521 DOI: 10.1021/jp7119813] [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] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
In this study, classical molecular dynamics simulations have been carried out on the valine (guest) substituted poly alanine (host) using the host-guest peptide approach to understand the role of valine in the formation and stabilization of helix. Valine has been substituted in the host peptide starting from N terminal to C terminal. Various structural parameters have been obtained from the molecular dynamics simulation to understand the tolerance of helical motif to valine. Depending on the position of valine in the host peptide, it stabilizes (or destabilizes) the formation of the helical structure. The substitution of valine in the poly alanine at some positions has no effect on the helix formation (deformation). It is interesting to observe the coexistence of 3 10 and alpha-helix in the peptides due to the dynamical nature of the hydrogen bonding interaction and sterical interactions.
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Affiliation(s)
- S Sundar Raman
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020 India
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Singh UK, Kumar M, Chauhan R, Jha PK, Ramanathan A, Subramanian V. Assessment of the impact of landfill on groundwater quality: a case study of the Pirana site in western India. Environ Monit Assess 2008; 141:309-21. [PMID: 17899419 DOI: 10.1007/s10661-007-9897-6] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2006] [Accepted: 08/27/2007] [Indexed: 05/17/2023]
Abstract
In present study focus has been given on estimating quality and toxicity of waste with respect to heavy metals and its impact on groundwater quality, using statistical and empirical relationships between different hydrochemical data, so that easy monitoring may be possible which in turn help the sustainable management of landfill site and municipal solid waste. Samples of solid waste, leachate and groundwater were analyzed to evaluate the impact of leachates on groundwater through the comparison of their hydrochemical nature. Results suggest the existence of an empirical relationship between some specific indicator parameters like heavy metals of all three above mentioned sample type. Further, K/Mg ratio also indicates three groundwater samples heavily impacted from leachate contamination. A good number of samples are also showing higher values for NO(3)(-) and Pb than that of World Health Organization (WHO) drinking water regulation. Predominance of Fe and Zn in both groundwater and solid waste samples may be due to metal plating industries in the area. Factor analysis is used as a tool to explain observed relation between numerous variables in term of simpler relation, which may help to deduce the strength of relation. Positive loading of most of the factors for heavy metal clearly shows landfill impact on ground water quality especially along the hydraulic gradient. Cluster analysis, further substantiates the impact of landfill. Two major groups of samples obtained from cluster analysis suggest that one group comprises samples that are severely under the influence of landfill and contaminated leachates along the groundwater flow direction while other assorted with samples without having such influence.
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Affiliation(s)
- Umesh Kumar Singh
- School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110 067, India
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De Proft F, Chattaraj PK, Ayers PW, Torrent-Sucarrat M, Elango M, Subramanian V, Giri S, Geerlings P. Initial Hardness Response and Hardness Profiles in the Study of Woodward–Hoffmann Rules for Electrocyclizations. J Chem Theory Comput 2008; 4:595-602. [DOI: 10.1021/ct700289p] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- F. De Proft
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels, Belgium, Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India, Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
| | - P. K. Chattaraj
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels, Belgium, Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India, Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
| | - P. W. Ayers
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels, Belgium, Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India, Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
| | - M. Torrent-Sucarrat
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels, Belgium, Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India, Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
| | - M. Elango
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels, Belgium, Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India, Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
| | - V. Subramanian
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels, Belgium, Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India, Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
| | - S. Giri
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels, Belgium, Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India, Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
| | - P. Geerlings
- Eenheid Algemene Chemie (ALGC), Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels, Belgium, Department of Chemistry and Center for Theoretical Studies, Indian Institute of Technology, Kharagpur 721302, India, Department of Chemistry, McMaster University, Hamilton, Ontario, Canada L8S 4M1, and Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
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156
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Affiliation(s)
- R. Parthasarathi
- a Chemical Laboratory , Central Leather Research Institute , Chennai, India
| | - V. Subramanian
- a Chemical Laboratory , Central Leather Research Institute , Chennai, India
| | - N. Sathyamurthy
- b Department of Chemistry , Indian Institute of Technology Kanpur , Kanpur, India
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157
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Rawat M, Singh UK, Mishra AK, Subramanian V. Methane emission and heavy metals quantification from selected landfill areas in India. Environ Monit Assess 2008; 137:67-74. [PMID: 17457681 DOI: 10.1007/s10661-007-9729-8] [Citation(s) in RCA: 3] [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] [Subscribe] [Scholar Register] [Received: 03/07/2006] [Accepted: 03/29/2007] [Indexed: 05/15/2023]
Abstract
In this study, an attempt has been made to study methane flux and quantification of heavy metals from Municipal Solid Waste (MSW) landfill areas of selected cities in India. During the period of study, the average value of methane flux was estimated from these landfill areas varied from 146-454 mg/m2/h. Methane emission from landfill is of serious environmental global concern as it accounts for approximately 15 percentages of current Greenhouse gas emissions. It has been estimated that methane emission, from landfill areas in the world, in next two decades would be same as that what is emitted from paddy fields presently. Besides, the estimation of methane flux, quantification of some heavy metals was conducted to analyse the suitability of using MSW as compost. The average values for metals were observed to be both within the range of USEPA and Indian standards for MSW disposal in landfill areas and to be used as compost respectively.
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Affiliation(s)
- Manju Rawat
- Lab No. 216/221, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
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158
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Raman SS, Vijayaraj R, Parthasarathi R, Subramanian V, Ramasami T. A molecular dynamics analysis of ion pairs formed by lysine in collagen: Implication for collagen function and stability. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.theochem.2007.11.030] [Citation(s) in RCA: 9] [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: 11/30/2022]
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159
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Chattaraj PK, Roy DR, Giri S, Mukherjee S, Subramanian V, Parthasarathi R, Bultinck P, Van Damme S. An atom counting and electrophilicity based QSTR approach. J CHEM SCI 2008. [DOI: 10.1007/s12039-007-0061-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [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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160
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Affiliation(s)
- S. Sundar Raman
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India, and Department of Science and Technology, New Mehrauli Road, New Delhi 110 016, India
| | - R. Parthasarathi
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India, and Department of Science and Technology, New Mehrauli Road, New Delhi 110 016, India
| | - V. Subramanian
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India, and Department of Science and Technology, New Mehrauli Road, New Delhi 110 016, India
| | - T. Ramasami
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India, and Department of Science and Technology, New Mehrauli Road, New Delhi 110 016, India
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161
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Vishwam T, Subramanian V, Subbaiah D, Murthy V. Conformational and microwave dielectric relaxation studies of hydrogen bonded polar binary mixtures of propionaldehyde with isopropyl amine. Mol Phys 2008. [DOI: 10.1080/00268970701832371] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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162
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Vishwam T, Chitra M, Subramanian V, Murthy V. Conformational and dielectric analysis of hydrogen bonded polar binary mixtures of propan-1-ol with isopropyl amine. J Mol Struct 2008. [DOI: 10.1016/j.molstruc.2007.02.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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163
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Parthasarathi R, Subramanian V, Sathyamurthy N. Hydrogen Bonding in Protonated Water Clusters: An Atoms-in-Molecules Perspective. J Phys Chem A 2007; 111:13287-90. [DOI: 10.1021/jp0775909] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- R. Parthasarathi
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India, and Indian Institute of Science Education and Research Mohali, MGSIPA Complex, Sector 26, Chandigarh 160 019, India
| | - V. Subramanian
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India, and Indian Institute of Science Education and Research Mohali, MGSIPA Complex, Sector 26, Chandigarh 160 019, India
| | - N. Sathyamurthy
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India, Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016, India, and Indian Institute of Science Education and Research Mohali, MGSIPA Complex, Sector 26, Chandigarh 160 019, India
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164
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Roy DR, Pal N, Mitra A, Bultinck P, Parthasarathi R, Subramanian V, Chattaraj PK. An atom counting strategy towards analyzing the biological activity of sex hormones. Eur J Med Chem 2007; 42:1365-9. [PMID: 17416442 DOI: 10.1016/j.ejmech.2007.01.028] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Revised: 01/25/2007] [Accepted: 01/29/2007] [Indexed: 12/01/2022]
Abstract
A simple and effective molecular descriptor, viz., the number of atoms in a molecule (N(A)) is made use of in the development of the quantitative structure-activity relationship (QSAR). A series of testosterone derivatives with various biological activities and estrogen derivatives with the activities in terms of relative binding affinity (RBA) are considered to find out the potential of N(A) in predicting the activities of those molecules. It is heartening to note that N(A) along with the electrophilicity index (omega) is capable of explaining the biological activities of the male and female hormones.
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Affiliation(s)
- D R Roy
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India
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165
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166
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Abstract
Children aged 6-15 years old experience more injuries to their teeth and the injuries sustained are more serious as evidenced by a higher percentage of luxations, avulsions, fractures and dislocations. The mandible is the most frequently fractured facial bone and mandibular alveolar injuries have been reported to range between 8.1-50.6%. Those with mandibular or midface fractures have a higher incidence of associated chest, extremity, abdomen and cervical spine injuries. The growing patient with facial injuries presents the clinician with a series of thought-provoking circumstances. Dentoalveolar and mandibular injuries are especially important to understand because of the potential complications related to tooth eruption, alveolar development, occlusion and facial growth. However, the principles involved in the treatment for children need to be modified by certain anatomical, physiological and psychological factors specifically related to childhood. This case report documents the trauma, management and follow-up care of an 11-year-old boy who sustained undisplaced infraorbital, nasal fractures and mandibular dentoalveolar fracture along with other associated injuries of the extremities.
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Affiliation(s)
- U M Das
- Department of Pedodontics and Preventive Dentistry, VS Dental College and Hospital, KR Road, VV Puram, Bangalore 560 004, Karnataka, India.
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167
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Vishwam T, Chitra M, Subramanian V, Murthy VRK. Conformational and dielectric analysis of hydrogen bonded polar binary mixtures of propan-1-ol with propionaldehyde. Mol Phys 2007. [DOI: 10.1080/00268970701684608] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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168
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Padmanabhan J, Parthasarathi R, Elango M, Subramanian V, Krishnamoorthy BS, Gutierrez-Oliva S, Toro-Labbé A, Roy DR, Chattaraj PK. Multiphilic Descriptor for Chemical Reactivity and Selectivity. J Phys Chem A 2007; 111:9130-8. [PMID: 17715901 DOI: 10.1021/jp0718909] [Citation(s) in RCA: 106] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In line with the local philicity concept proposed by Chattaraj et al. (Chattaraj, P. K.; Maiti, B.; Sarkar, U. J. Phys. Chem. A. 2003, 107, 4973) and a dual descriptor derived by Morell, Grand and Toro-Labbé, (J. Phys. Chem. A 2005, 109, 205), we propose a multiphilic descriptor. It is defined as the difference between nucleophilic (omega(k)+) and electrophilic (omega(k)-) condensed philicity functions. This descriptor is capable of simultaneously explaining the nucleophilicity and electrophilicity of the given atomic sites in the molecule. Variation of these quantities along the path of a soft reaction is also analyzed. Predictive ability of this descriptor has been successfully tested on the selected systems and reactions. Corresponding force profiles are also analyzed in some representative cases. Also, to study the intra- and intermolecular reactivities another related descriptor, namely, the nucleophilicity excess (Deltaomega(g)-/+) for a nucleophile over the electrophilicity in it, has been defined and tested on all-metal aromatic compounds.
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Affiliation(s)
- J Padmanabhan
- Department of Chemistry, Indian Institute of Technology, Kharagpur 721302, India
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169
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Elango M, Parthasarathi R, Subramanian V, Sathyamurthy N. Bowls, balls and sheets of boric acid clusters: the role of pentagon and hexagon motifs. J Phys Chem A 2007; 109:8587-93. [PMID: 16834258 DOI: 10.1021/jp053382+] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [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: 11/30/2022]
Abstract
Ab initio calculations suggest the possibility of forming boric acid clusters in the laboratory. The most stable form of the boric acid dimer contains two hydrogen bonds, similar to the carboxylic acid dimers. Though the trimer and the tetramer form extensions of this geometry, the pentamer prefers a bowl shape. Any addition of boric acid molecules to this geometry leads to bowl-shaped structures with the 15-mer forming a (3/4)buckyball and the 20-mer a full-fledged buckyball. The hexamer, on the other hand, prefers to stay planar as a hexagon-centered rosette. Any further extension of this geometry leads to planar structures as long as a pentagon is not included.
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Affiliation(s)
- M Elango
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai, India 600 020
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170
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Parthasarathi R, Raman SS, Subramanian V, Ramasami T. Bader's Electron Density Analysis of Hydrogen Bonding in Secondary Structural Elements of Protein. J Phys Chem A 2007; 111:7141-8. [PMID: 17602540 DOI: 10.1021/jp071513w] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [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: 11/28/2022]
Abstract
The hydrogen-bonding (H-bonding) interactions in alpha-helical and beta-sheet model peptides have been studied by using the atoms-in-molecule (AIM) approach. The relative importance of NH...O and CH...O H-bonding interactions in the different secondary elements such as alpha-helix, parallel, and antiparallel beta-sheets have been assessed. The electron density values at the NH...O bond are higher than those of the CH...O bonds in the alpha-helical conformation. The electron density values at the H-bonded critical points (HBCPs) corresponding to NH...O and CH...O interactions are nearly equal in the parallel beta-sheet of the order of 10(-3) au, whereas in the case of antiparallel beta-sheets, rho(rc) values for NH...O and CH...O interactions are of the order of 10(-2) and 10(-3) au, respectively. It is interesting to point out here that the weakening of NH...O interactions in the parallel beta-sheet arrangement is evident from the AIM analysis. This is concomitant with the increase in the NH...O distance in the parallel beta-sheet conformation. In addition to the clear description of H-bonding by electron density at the HBCP, possible good linear relationships between the electron density at ring critical points (RCP) and stabilization energy (SE) have been observed corresponding to the various beta-sheet conformations.
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Affiliation(s)
- R Parthasarathi
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India
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171
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Abstract
It is shown that the electron density at the hydrogen bond critical point increases approximately linearly with increasing stabilization energy in going from weak hydrogen bonds to moderate and strong hydrogen bonds, thus serving as an indicator of the nature and gradual change of strength of the hydrogen bond for a large number of test intermolecular complexes.
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172
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Vishwam T, Chitra M, Subramanian V, Murthy V. Experimental and theoretical analysis of hydrogen bonded polar system of isobutanol and isobutyraldehyde. J Mol Liq 2007. [DOI: 10.1016/j.molliq.2006.10.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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173
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Vishwam T, Subramanian V, Murthy VRK. Microwave dielectric absorption studies of hydrogen bonded polar binary mixtures of isobutanol with tertiary butyl amine. Mol Phys 2007. [DOI: 10.1080/00268970701250293] [Citation(s) in RCA: 2] [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: 10/23/2022]
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174
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175
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Sundaray B, Subramanian V, Natarajan TS. Preparation and characterization of polystyrene-multiwalled carbon nanotube composite fibers by electrospinning. J Nanosci Nanotechnol 2007; 7:1793-5. [PMID: 17654941 DOI: 10.1166/jnn.2007.717] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
Electrospinning is a simple technique to prepare polymer fibers in nanometer diameters using very high electrostatic fields. These nanofibers are useful in many applications since the surface area to volume ratio in these fibers is very high. Here we have prepared nanofibers of composites of Polystyrene (PS) with different concentrations (0.05% to 2% w/w) of multi-walled carbon nanotubes (MWCNT) by electrospinning. The fibers are characterized by SEM, TEM, Raman spectra, and TGA. The room temperature electrical conductivity of single fibers of these composites are measured and found to show dramatic improvement in the conductivity due to the addition of MWCNT to the polymer matrix compared to the pure PS.
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176
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Padmanabhan J, Parthasarathi R, Subramanian V, Chattaraj P. Philicity based site activation model towards understanding the Markovnikov regioselectivity rule. ACTA ACUST UNITED AC 2007. [DOI: 10.1016/j.theochem.2006.09.022] [Citation(s) in RCA: 11] [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: 10/24/2022]
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177
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Subramanian V, Banerjee A, Beharry N, Farthing MJG, Pollok RCG. Determining the proximal extent of ulcerative colitis: white cell scan correlates well with histological assessment. Aliment Pharmacol Ther 2007; 25:441-6. [PMID: 17269999 DOI: 10.1111/j.1365-2036.2006.03222.x] [Citation(s) in RCA: 3] [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] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND Assessing the extent of ulcerative colitis determines therapeutic strategies and provides prognostic information. Colonoscopy with mucosal biopsy is considered unsafe in patients with severe disease. AIM To assess the correlation between proximal extent of ulcerative colitis as determined by Technitium-99-m hexamethylpropylene amine oxime labelled leucocyte scan (white cell scan) with that determined by histological assessment. METHODS One hundred and thirty-five patients, with histologically-confirmed ulcerative colitis, who had a white cell scan and histological assessment of colonic inflammation within 6 months of each other, during the years 1991-2004, were included. Overall agreement, quadratic-weighted kappa (kappa) and polychoric correlations (rho) were calculated to estimate the inter-rater reliability. RESULTS The correlation between white cell scan and histological extent was excellent (kappa = 0.7 rho = 0.8). Macroscopic appearance on colonoscopy did not correlate as well with histological extent (kappa = 0.62 and rho = 0.67). White cell scans correlated significantly better in patients with extensive disease (P = 0.02). Colonoscopy predicted disease extent more accurately in patients with limited colitis (P = 0.002). CONCLUSIONS Proximal extent of ulcerative colitis determined by white cell scans correlates well with histological assessment especially in patients with more extensive disease. White cell scans offer a reasonable alternative to colonoscopy with mucosal biopsies in determining the proximal extent of colitis.
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Affiliation(s)
- V Subramanian
- Departments of Gastroenterology, St george's Healthcae NHS Trust, Blackshaw Road, London, UK.
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178
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Abstract
In line with the charge transfer (DeltaNmax = -mu/eta) proposed by Parr et al. (Parr, R. G.; Szentpály, L. V.; Liu, S. J. Am. Chem. Soc. 1999, 121, 1922), we propose an electrophilicity-based charge transfer (ECT) descriptor in this paper and validate it through the interaction between a series of chlorophenols and DNA bases. Application of ECT can be extended to the interaction of any toxin with the biosystem.
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Affiliation(s)
- J Padmanabhan
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India
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180
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Prathab B, Subramanian V, Aminabhavi T. Computation of surface energy and surface segregation phenomena of perfluorinated copolymers and blends – A molecular modeling approach. POLYMER 2007. [DOI: 10.1016/j.polymer.2006.10.043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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181
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Murthy DVB, Subramanian V, Pavan Kumar VS, Natarajan TS, Raghuraman GK, Dhamodharan R, Murthy VRK. Microwave hall mobility studies on polymer–metal oxide nanocomposites. J Appl Polym Sci 2007. [DOI: 10.1002/app.27240] [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: 11/06/2022]
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Parthasarathi R, Subramanian V, Sathyamurthy N, Leszczynski J. Solvation of H3O+ by Phenol: Hydrogen Bonding vs π Complexation. J Phys Chem A 2006; 111:2-5. [PMID: 17201380 DOI: 10.1021/jp066574t] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ab initio calculations at the second-order Møller-Plesset perturbation theoretic level have been carried out to study the solvation of protonated water by phenol molecules. The results show that in addition to classical O-H...O hydrogen bonds, C-H...O, pi...H-O, and pi...H-C bonds are also formed, thus stabilizing the H3O+(C(6)H(5)OH)3 complex.
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Padmanabhan J, Parthasarathi R, Subramanian V, Chattaraj P. Chemical information insights into the series of chloroanisoles – A theoretical approach. ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.theochem.2006.06.027] [Citation(s) in RCA: 8] [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: 10/24/2022]
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Yadav JS, Doddapaneni H, Subramanian V. P450ome of the white rot fungus Phanerochaete chrysosporium: structure, evolution and regulation of expression of genomic P450 clusters. Biochem Soc Trans 2006; 34:1165-9. [PMID: 17073777 DOI: 10.1042/bst0341165] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.8] [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: 11/17/2022]
Abstract
The model white rot fungus Phanerochaete chrysosporium has the extraordinary ability to degrade (to CO2) lignin and detoxify a variety of chemical pollutants. Whole genome sequencing of this fungus has revealed the presence of the largest P450ome in fungi comprising approx. 150 P450 genes, most of which have unknown function. On the basis of our genome-wide structural and evolutionary analysis, these P450 genes could be classified into 12 families and 23 subfamilies and under 11 fungal P450 clans. The analysis further revealed an extensive gene clustering with a total of 16 P450 clusters constituted of up to 11 members per cluster. In particular, evidence and role of gene duplications and horizontal gene transfer in the evolution of these P450 clusters have been discussed using two of the P450 families [CYP63 and CYP505 (where CYP is cytochrome P450)] as examples. In addition, the observed differential transcriptional induction of the clustered members of the CYP63 gene family, in response to different xenobiotic chemicals and carbon sources, indicated functional divergence within the P450 clusters, of this basidiomycete fungus.
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Affiliation(s)
- J S Yadav
- Molecular Toxicology Division, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH 45267-0056, USA.
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Raman SS, Parthasarathi R, Subramanian V, Ramasami T. Role of Aspartic Acid in Collagen Structure and Stability: A Molecular Dynamics Investigation. J Phys Chem B 2006; 110:20678-85. [PMID: 17034259 DOI: 10.1021/jp0625715] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [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: 11/28/2022]
Abstract
A molecular dynamics (MD) simulation study has been carried out to understand the stability of the triple helical collagen models. The calculations show that the presence of the aspartic acid residue in different positions leads to the local variation in the structure. Analyses of root-mean-square deviation (RMSD), radial distribution function (RDF), puckering effect, dihedral angle variation, hydrogen bond (H-bond), and conformational changes during molecular dynamics simulation reveal that the local perturbation in the sequences, increase in chain flexibility due to removal of five membered rings in the collagen by aspartic acid, change of intermolecular H-bonding pattern, and differences in the association of water are mainly influencing the nature of stabilization of collagen by aspartic acid.
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Affiliation(s)
- S Sundar Raman
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India
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186
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Subramanian V. 146 Asbestos problems in India: A revisit. Lung Cancer 2006. [DOI: 10.1016/s0169-5002(07)70222-2] [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: 11/16/2022]
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187
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Prathab B, Aminabhavi TM, Parthasarathi R, Manikandan P, Subramanian V. Molecular modeling and atomistic simulation strategies to determine surface properties of perfluorinated homopolymers and their random copolymers. POLYMER 2006. [DOI: 10.1016/j.polymer.2006.07.034] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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188
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Southerland EM, Milhorn DM, Foreman RD, Linderoth B, DeJongste MJL, Armour JA, Subramanian V, Singh M, Singh K, Ardell JL. Preemptive, but not reactive, spinal cord stimulation mitigates transient ischemia-induced myocardial infarction via cardiac adrenergic neurons. Am J Physiol Heart Circ Physiol 2006; 292:H311-7. [PMID: 16920800 DOI: 10.1152/ajpheart.00087.2006] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Our objective was to determine whether electrical neuromodulation using spinal cord stimulation (SCS) mitigates transient ischemia-induced ventricular infarction and, if so, whether adrenergic neurons are involved in such cardioprotection. The hearts of anesthetized rabbits, subjected to 30 min of left anterior descending coronary arterial occlusion (CAO) followed by 3 h of reperfusion (control), were compared with those with preemptive SCS (starting 15 min before and continuing throughout the 30-min CAO) or reactive SCS (started at 1 or 28 min of CAO). For SCS, the dorsal C8-T2 segments of the spinal cord were stimulated electrically (50 Hz, 0.2 ms, 90% of motor threshold). For preemptive SCS, separate groups of animals were pretreated 15 min before SCS onset with 1) vehicle, 2) prazosin (alpha(1)-adrenoceptor blockade), or 3) timolol (beta-adrenoceptor blockade). Infarct size (IS), measured with tetrazolium, was expressed as a percentage of risk zone. In controls exposed to 30 min of CAO, IS was 36.4 +/- 9.5% (SD). Preemptive SCS reduced IS to 21.8 +/- 6.8% (P < 0.001). Preemptive SCS-mediated infarct reduction was eliminated by prazosin (36.6 +/- 8.8%) and blunted by timolol (29.4 +/- 7.5%). Reactive SCS did not reduce IS. SCS increased phosphorylation of cardiac PKC. SCS did not alter blood pressure or heart rate. We conclude that preemptive SCS reduces the size of infarcts induced by transient CAO; such cardioprotection involves cardiac adrenergic neurons.
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Affiliation(s)
- E M Southerland
- Dept. of Pharmacology, East Tennessee State Univ., James H. Quillen College of Medicine, Johnson City, TN 37614-0577, USA.
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Prathab B, Aminabhavi TM, Parthasarathi R, Subramanian V. Computation of density of perfluoroalkyl methacrylates: a molecular modeling approach. Theor Chem Acc 2006. [DOI: 10.1007/s00214-006-0156-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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190
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Abstract
The environmental effects of chloroanilines depend on their physical and chemical properties, and it is therefore important to know their structure-property relationships that allow a complete understanding of their environmental consequences. The chemical reactivity profiles of all 19 chloroanilines have been investigated using the density functional theory for the first time. Global reactivity descriptors, such as hardness, chemical potential, electrophilicity index, and polarizability, and local reactivity descriptors, namely, local philicities, have been calculated in order to gain insights into the reactive nature and the reactive sites of the selected systems. Using AIM theory, the presence of hydrogen bond critical points (HBCPs) and the values of electron density and Laplacian of electron density at the HBCPs have been analyzed to appreciate the presence of intramolecular hydrogen bonding in the selected systems. Structure-toxicity analysis of the selected set of chloroanilines demonstrates the importance of the electrophilicity index in the prediction of reactivity/toxicity.
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Affiliation(s)
- J Padmanabhan
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
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Radhakrishnan S, Parthasarathi R, Subramanian V, Somanathan N. Molecular Orbital Calculations on Polythiophenes Containing Heterocyclic Substituents: Effect of Structure on Electronic Transitions. J Phys Chem B 2006; 110:14078-86. [PMID: 16854103 DOI: 10.1021/jp0566461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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: 11/28/2022]
Abstract
Molecular orbital calculations have been performed on thiophene oligomers bearing heterocyclic substituents at the third position in order to understand the interplay of effects such as the nature of substituent, skeletal substitution pattern, heteroatom identity, etc. on electronic transitions. The geometry optimization was carried out using the semiempirical AM1 method, and the electronic transitions predicted for the oligomers were extrapolated for polymers using an oligomeric approach. The experimentally determined optical transitions were found to follow the predicted trend of electronic transitions of monomers and polymers.
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Affiliation(s)
- S Radhakrishnan
- Central Leather Research Institute, Adyar, Chennai 600 020, India
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Padmanabhan J, Parthasarathi R, Subramanian V, Chattaraj PK. Group philicity and electrophilicity as possible descriptors for modeling ecotoxicity applied to chlorophenols. Chem Res Toxicol 2006; 19:356-64. [PMID: 16544939 DOI: 10.1021/tx050322m] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [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: 11/29/2022]
Abstract
The search for the best quantitative structure-activity relationship (QSAR) models in ecotoxicology is an ever-topical research activity. Hence, the development of new descriptors and applying them successfully in QSAR studies seems demanding in ecotoxicology. In the present work, group philicities are utilized for the first time in QSAR analysis for ecotoxicological studies on chlorophenols (CPs). It is important to point out that group philicities are capable of providing the best QSAR model for the toxicity of CPs against Daphnia magna. Furthermore, global electrophilicity and group philicities together give the best QSAR models for Brachydanio rerio and Bacillus with the maximum value of coefficient of determination and high internal predictive ability. The developed QSAR models clearly show the importance of the selected density functional reactivity indices as descriptors in ecotoxicological studies.
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Affiliation(s)
- J Padmanabhan
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600020, India
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Roy DR, Sarkar U, Chattaraj PK, Mitra A, Padmanabhan J, Parthasarathi R, Subramanian V, Van Damme S, Bultinck P. Analyzing Toxicity Through Electrophilicity. Mol Divers 2006; 10:119-31. [PMID: 16763875 DOI: 10.1007/s11030-005-9009-x] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Accepted: 12/20/2005] [Indexed: 10/24/2022]
Abstract
The toxicological structure-activity relationships are investigated using conceptual DFT based descriptors like global and local electrophilicities. In the present work the usefulness of electrophilicity in predicting toxicity of several polyaromatic hydrocarbons (PAH) is assessed. The toxicity is expressed through biological activity data (pIC50) defined as molar concentration of those chemicals necessary to displace 50% of radiolabeled tetrachlorodibenzo-p-dioxin (TCDD) from the arylhydrocarbon (Ah) receptor. The experimental toxicity values (pIC50) for the electron acceptor toxin like polychlorinated dibenzofurans (PCDF) are taken as dependent variables and the DFT based global descriptor electrophilicity index (omega) is taken as independent variable in the training set. The same model is then tested on a test set of polychlorinated biphenyls (PCB). A good correlation is obtained which vindicates the importance of these descriptors in the QSAR studies on toxins. These toxins act as electron acceptors in the presence of biomolecules whereas aliphatic amines behave as electron donors some of which are also taken into account for the present work. The toxicity values of the aliphatic amines in terms of the 50% inhibitory growth concentration (IGC50) towards ciliate fresh-water protozoa Tetrahymena pyriformis are considered. Since there is no global nucleophilicity we apply local nucleophilicity (omegamax+) as the descriptor in this case of training set. The same regression model is then applied to a test set of amino alcohols. Although the correlation is very good the statistical analysis reflects some cross validation problem. As a further check the amines and amino alcohols are used together to form both the training and the test sets to provide good correlation. It is demonstrated that the toxicity of several toxins (both electron donors and acceptors) in the gas and solution phases can be adequately explained in terms of global and local electrophilicities. Amount of charge transfer between the toxin and the biosystem, simulated as nucleic acid bases and DNA base pairs, indicates the importance of charge transfer in the observed toxicity. The major strength of the present analysis vis-à-vis the existing ones rests on the fact that it requires only one descriptor having a direct relationship with toxicity to provide a better correlation. Importance of using the information from both the toxin and the biosystem is also analyzed.
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Affiliation(s)
- D R Roy
- Department of Chemistry, Indian Institute of Technology, Kharagpur, 721302, India
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Lahiri D, Subramanian V, Bunker BA, Kamat PV. Probing photochemical transformations at TiO2∕Pt and TiO2∕Ir interfaces using x-ray absorption spectroscopy. J Chem Phys 2006; 124:204720. [PMID: 16774377 DOI: 10.1063/1.2198193] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Structural transformations at the TiO2Pt and TiO2Ir interfaces during UV-irradiation have been probed by X-ray absorption spectroscopy. Oxidation by the photogenerated holes results in the intercalation of Pt and Ir into the Titania matrix. The structural transformations observed with Pt and Ir nanoparticles anchored on TiO2 is different than the clustering of gold atoms observed in the TiO2/Au system. Implications of such structural transformations on the photocatalytic activity of semiconductor photocatalyts are discussed.
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Affiliation(s)
- Debdutta Lahiri
- Synchrotron Radiation Section, Physics Group, Bhabha Atomic Research Centre, Mumbai 400085, India.
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Subramanian V, Pollok RCG, Kang JY, Kumar D. Systematic review of postoperative complications in patients with inflammatory bowel disease treated with immunomodulators. Br J Surg 2006; 93:793-9. [PMID: 16710880 DOI: 10.1002/bjs.5375] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [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: 11/11/2022]
Abstract
Abstract
Background
This systematic review examined the use of immunomodulators and the risk of postoperative complications after abdominal surgery in patients with inflammatory bowel disease.
Methods
Electronic databases (PubMed, Embase, Ingenta, Zetoc and Ovid) were searched and the reference lists in all articles identified were hand-searched for further relevant papers. Studies were included if they evaluated postoperative complications and defined exposure to individual immunomodulators.
Results
All 11 studies that met the inclusion criteria were observational studies; two were reported only in abstract form. Five studies reported risks associated with azathioprine, five reported risks associated with cyclosporin and three reported risks associated with infliximab. None showed an increased risk of either total or infectious complications associated with immunomodulator use. However, subgroup analysis in one study, published as an abstract, suggested increased rates of anastomotic complications and reoperation associated with azathioprine.
Conclusion
Available evidence does not suggest an increased rate of postoperative complications associated with immunomodulator use.
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Affiliation(s)
- V Subramanian
- Department of Gastroenterology, St George's Hospital NHS Trust, London, UK.
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196
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Abstract
Acid-base dissociation constants (pK(a) values) are important in understanding the chemical, environmental and toxicological properties of molecules. Though various methods have been developed to predict pK(a) by experimental and theoretical models, prediction of pK(a) is still complicated. Hence, a new approach for predicting pK(a) using the group philicity concept has been attempted. Presence of known functional groups in a molecule is utilized as the most important indicator to predict pK(a). The power of this descriptor in describing pK(a) for the series of carboxylic acids, various substituted phenols, anilines, phosphoric acids, and alcohols is probed. Results reveal that the group electrophilicity is suitable for effectively predicting the pK(a) values.
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Affiliation(s)
- R Parthasarathi
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India
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197
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Elango M, Parthasarathi R, Subramanian V, Ramachandran CN, Sathyamurthy N. Hydrogen Peroxide Clusters: The Role of Open Book Motif in Cage and Helical Structures. J Phys Chem A 2006; 110:6294-300. [PMID: 16686465 DOI: 10.1021/jp055818r] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [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: 01/27/2023]
Abstract
Hartree-Fock (HF) calculations using 6-31G*, 6-311++G(d,p), aug-cc-pVDZ, and aug-cc-pVTZ basis sets show that hydrogen peroxide molecular clusters tend to form hydrogen-bonded cyclic and cage structures along the lines expected of a molecule which can act as a proton donor as well as an acceptor. These results are reiterated by density functional theoretic (DFT) calculations with B3LYP parametrization and also by second-order Møller-Plesset perturbation (MP2) theory using 6-31G* and 6-311++G(d,p) basis sets. Trends in stabilization energies and geometrical parameters obtained at the HF level using 6-311++G(d,p), aug-cc-pVDZ, and aug-cc-pVTZ basis sets are similar to those obtained from HF/6-31G* calculation. In addition, the HF calculations suggest the formation of stable helical structures for larger clusters, provided the neighbors form an open book structure.
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Affiliation(s)
- M Elango
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai, India 600 020
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Abstract
OBJECTIVE To study the role of beta1 integrins in left ventricular (LV) remodelling after myocardial infarction (MI). METHODS AND RESULTS LV structural and functional alterations were determined in wild-type (WT) and beta1 integrin heterozygous knockout (hKO) mice one month after MI. MI increased beta1 integrin expression in both groups; however, the increase was lower in hKO. Infarct size was similar in WT and hKO mice, whereas lung wet weight to dry weight ratio was increased in the hKO-MI mice (5.17 (SE 0.13) v 4.60 (0.15) in WT-MI, p < 0.01). LV end systolic and end diastolic diameters were significantly higher and percentage fractional shortening was significantly lower in hKO-MI. The ratio of peak velocity of early LV filling (E wave) to that of the late LV filling (A wave) and the isovolumic relaxation time (IVRT) were increased in both MI groups but the increase in IVRT was significantly higher in hKO-MI group than in WT-MI mice. Langendorff perfusion analysis indicated reduced peak LV developed pressure and increased LV end diastolic pressure in both MI groups. The reduction in peak LV developed pressure (36.7 (2.2) v 53.4 (1.9) mm Hg, p < 0.05) and increase in LV end diastolic pressure was higher in hKO-MI than in WT-MI. Increase in fibrosis was not different between the two MI groups. The increase in myocyte circumference was higher in the hKO-MI group (p < 0.001 v WT-MI). The number of apoptotic myocytes was significantly higher in hKO-MI than in WT-MI mice (p < 0.005) three days after MI. The number of necrotic myocytes was not different between the two MI groups. CONCLUSION beta1 integrins are crucial in post-MI remodelling with effects on LV function, hypertrophy and apoptosis.
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Affiliation(s)
- P Krishnamurthy
- Department of Physiology, James H Quillen College of Medicine, James H Quillen Veterans Affairs Medical Center, East Tennessee State University, Johnson City, Tennessee 37614, USA
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Abstract
We demonstrate the high-rate capability of lithium ion insertion-deinsertion reactions in carbon nanofibers (CNFs). The morphology of CNFs with structural and surface defects, due to the mixed features of disordered and graphitic carbon, plays an important role in both the enhancement of the lithium ion storage and the rate-determining reactions during the topotactic process. The reversible specific capacity of the CNFs at a 0.1 C rate was 461 mA x h/g. The most promising property, which is expected to overcome the hurdles of lithium batteries for high-power applications, is that they deliver considerably high specific capacity even at a very high charge-discharge current, i.e., at a cycling rate of 10 C the reversible capacity is around 170 mA x h/g with a 95% Coulombic efficiency.
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Affiliation(s)
- V Subramanian
- Department of Electrical and Computer Engineering, and Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803, USA
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Padmanabhan J, Parthasarathi R, Subramanian V, Chattaraj PK. Chemical Reactivity Indices for the Complete Series of Chlorinated Benzenes: Solvent Effect. J Phys Chem A 2006; 110:2739-45. [PMID: 16494385 DOI: 10.1021/jp056630a] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [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: 11/28/2022]
Abstract
We present a comprehensive analysis to probe the effect of solvation on the reactivity of the complete series of chlorobenzenes through the conceptual density functional theory (DFT)-based global and local descriptors. We propose a multiphilic descriptor in this study to explore the nature of attack at a particular site in a molecule. It is defined as the difference between nucleophilic and electrophilic condensed philicity functions. This descriptor is capable of explaining both the nucleophilicity and electrophilicity of the given atomic sites in the molecule simultaneously. The predictive ability of this descriptor is tested on the complete series of chlorobenzenes in gas and solvent media. A structure-toxicity analysis of these entire sets of chlorobenzenes toward aquatic organisms demonstrates the importance of the electrophilicity index in the prediction of the reactivity/toxicity.
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Affiliation(s)
- J Padmanabhan
- Chemical Laboratory, Central Leather Research Institute, Adyar, Chennai 600 020, India
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