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Mohan M, Nayak S, Pal A, Murugavel P. Bipolar magnetic switching and large exchange-bias in Fe-substituted SmCrO 3. J Phys Condens Matter 2023; 35:475801. [PMID: 37595609 DOI: 10.1088/1361-648x/acf1ea] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 08/18/2023] [Indexed: 08/20/2023]
Abstract
Rare-earth orthochromite is an interesting system in the view of its complex magnetic ordering due to competing interaction between different magnetic ions. Here, Fe-substituted SmCrO3samples were prepared by solid-state route to investigate their intriguing magnetic properties towards exploring its application potential. The magnetic studies revealed antiferromagnetic (AFM) ordering at Nèel temperature (TN) ∼ 181 K, magnetic compensation temperatures (TCOMP) at ∼137 K and 50 K, and spin-reorientation temperature (TSR) at 64 K in SmCr0.8Fe0.2O3sample. Additionally, the system exhibited negative magnetization under field-cooled conditions which allowed the field as well as temperature controllable magnetization switching behavior. Notably, the Fe-substituted SmCrO3sample displayed a remarkable exchange bias (HEB) value of ∼1.39 T at 10 K due to the coexistence of ferromagnetic and AFM ordering at different cationic sites. TheM-Hloops recorded under positive and negative field-cooled conditions ruled out the minor-loop effect. Theoretical models applied on the training effect studies confirmed the observed exchange-bias effect.
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Affiliation(s)
- Manu Mohan
- Pervoskite Materials Laboratory, Functional Oxides Research Group (FORG), Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - Sanjib Nayak
- Pervoskite Materials Laboratory, Functional Oxides Research Group (FORG), Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - Arnab Pal
- Pervoskite Materials Laboratory, Functional Oxides Research Group (FORG), Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
| | - P Murugavel
- Pervoskite Materials Laboratory, Functional Oxides Research Group (FORG), Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
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Pal S, Mohan M, Priya KS, Murugavel P. Photoelectrocaloric effect in ferroelectric oxide. Sci Rep 2022; 12:6390. [PMID: 35430579 PMCID: PMC9013360 DOI: 10.1038/s41598-022-10331-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 04/04/2022] [Indexed: 11/27/2022] Open
Abstract
The enhanced electrocaloric (EC) effect in solid-state-based lead-free ferroelectric Ba0.875(Bi0.5Li0.5)0.125TiO3 system is investigated under light as an external stimulus. The sample exhibits an analogous value of maximum change in entropy at Curie temperature, extracted from the two different measurements process. Notably, the sample depicts maximum value of adiabatic change in temperature (ΔT) as 1.27 K and isothermal entropy change (ΔS) as 2.05 J/K kg along with the EC coefficient value of 0.426 K mm/kV, under dark conditions. In addition, the sample exhibits > 0.5 K adiabatic temperature change over a broad temperature range (~ 35 K). Remarkably, the EC parameters display ~ 27% enhancement upon 405 nm light illumination. The demonstrated photoelectrocaloric effect is found to be in accordance with theoretical formalism. The present work elucidates the light as an additional degree of freedom to widen the potential of solid-state-based technologies for advanced environment-friendly cooling devices.
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Priya K S, Kola L, Pal S, Biswas PP, Murugavel P. Physical vapor deposited organic ferroelectric diisopropylammonium bromide film and its self-powered photodetector characteristics. RSC Adv 2020; 10:25773-25779. [PMID: 35518576 PMCID: PMC9055340 DOI: 10.1039/d0ra03968c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Accepted: 06/28/2020] [Indexed: 11/21/2022] Open
Abstract
Organic diisopropylammonium bromide (DIPAB) is a promising material with superior ferroelectric characteristics. However, the DIPAB continuous film, which is essential to explore its application potential, is challenging because its crystallization kinetics favors island-like microcrystalline growth. In this work, the continuous and uniform deposition of organic ferroelectric DIPAB film on a single crystalline Si(100) substrate is demonstrated by a thermal evaporation process. Structural and optical studies reveal that the film is c-axis oriented with an optical bandgap of 3.52 eV. The topographic image displays well-connected grain-like surface morphology with ∼2 nm roughness. The ferroelectric domain studies illustrate the in-plane orientation of the domains, which is in accordance with c-axis oriented film where polarization is along the in-plane b-axis. The phase and amplitude responses of the domains display hysteresis and butterfly characteristics, respectively and thereby endorse the ferroelectric nature of the film. Importantly, it is demonstrated that the DIPAB film exhibits remarkable self-powered UV-Vis photodetector characteristics with responsivity of 0.66 mA W-1 and detectivity of 2.20 × 109 Jones at 11.45 mW cm-2 light intensity. The fabricated DIPAB film reported in this work can widen its application potential in self-powered photodetector and other optoelectronic devices.
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Affiliation(s)
- Shanmuga Priya K
- Department of Physics, Indian Institute of Technology Madras Chennai-600036 India
| | - Lakshmi Kola
- Department of Physics, Indian Institute of Technology Madras Chennai-600036 India
| | - Subhajit Pal
- Department of Physics, Indian Institute of Technology Madras Chennai-600036 India
| | | | - P Murugavel
- Department of Physics, Indian Institute of Technology Madras Chennai-600036 India
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Sahoo S, Ravindran T, Srihari V, Pandey K, Chandra S, Thirmal C, Murugavel P. Pressure induced phase transformations in diisopropylammonium bromide. J SOLID STATE CHEM 2019. [DOI: 10.1016/j.jssc.2019.03.025] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Abstract
The evolution of various spin structures in Yb doped GdMnO3 distorted orthorhombic perovskite system was investigated from their magnetic, dielectric and magnetodielectric characteristics. The Gd1-x Yb x MnO3 (0 ⩽ x ⩽ 0.15) revealed an enhanced magnetodielectric coupling when their magnetic structure is guided from ab to the bc-cycloidal spin structure upon Yb doping. The compounds exhibit magnetic field and temperature controlled spin-flop from c to a-axis. Additionally, magnetodielectric reversal is observed for the x = 0.1 sample which depends on both magnetic field and temperature. The resultant correlation between magnetic and electric orderings is discussed in the frame of symmetric and antisymmetric exchange interaction models. These findings provide further insight in understanding the magnetoelectric materials and importantly show a way to tune the magnetic and magnetodielectric properties towards better application potential.
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Affiliation(s)
- A Pal
- Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
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Pal A, Dhana Sekhar C, Venimadhav A, Murugavel P. Tailoring of magnetic orderings in Fe substituted GdMnO 3 bulk samples towards room temperature. J Phys Condens Matter 2017; 29:405803. [PMID: 28718778 DOI: 10.1088/1361-648x/aa8083] [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] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The evolution of various magnetic ordering has been studied for the orthorhombic perovskite GdMn1-x Fe x O3 (0 ⩽ x ⩽ 0.7) system to obtain its comprehensive magnetic phase diagram. We observed that the substitution of Fe in GdMnO3 increases the antiferromagnetic Neel temperature (T N) from 40 K to above 400 K and importantly induces a spin-reorientation transition (T SR) for x ⩾ 0.4. These transitions are close to room temperature at x = 0.5 and then gradually separated at a higher x value. The static orbital ordering induced by the Jahn-Teller distortion seems to play an important role in changing the T N. The variations of spin-reorientation ordering along with the competition between the magnetic orderings as a function of the composition were discussed with respect to antisymmetric exchange interactions and Mn3+ single-ion anisotropy in detail. In addition, the correlation between structural and magnetic properties suggests that the subtle structural change at composition x = 0.4 may affect the magnetic ordering. The observed tunable T SR and T N in GdMn1-x Fe x O3 could add a practical value for these compositions in fields like spintronics and sensors.
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Affiliation(s)
- A Pal
- Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India
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Sahoo S, Ravindran TR, Chandra S, Sarguna RM, Das BK, Sairam TN, Sivasubramanian V, Thirmal C, Murugavel P. Vibrational spectroscopic and computational studies on diisopropylammonium bromide. Spectrochim Acta A Mol Biomol Spectrosc 2017; 184:211-219. [PMID: 28499175 DOI: 10.1016/j.saa.2017.05.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Revised: 05/02/2017] [Accepted: 05/04/2017] [Indexed: 06/07/2023]
Abstract
Diisopropylammonium bromide (DIPAB) can be crystallized either in an orthorhombic (P212121) or in a monoclinic (P21) structure at room temperature depending on synthesis conditions. The non-polar orthorhombic structure exhibits a subtle, irreversible transformation into the ferroelectric monoclinic-II (m-II) phase above ~421K. At a slightly higher temperature of 426K this m-II (P21) phase reversibly transforms into a disordered, paraelectric monoclinic-I (P21/m) structure. We synthesized DIPAB in the orthorhombic structure, heated it to obtain the m-II phase and carried out a systematic study of their Raman and IR spectra. We obtained the phonon irreducible representations from factor group analysis of the orthorhombic and m-II structures based on the reported structural information. DIPAB is an organic molecular crystal, and the vibrational spectra in the intramolecular region (200-3500cm-1) of the two different phases are identical to each other, indicating weak inter-molecular interactions in both crystalline structures. In the low wavenumber region (10-150cm-1) the Raman spectra of the two phases are different due to their sensitivity to molecular environment. We also carried out first principles calculations using Gaussian 09 and CASTEP codes to analyze the vibrational frequencies. Mode assignments were facilitated by isolated molecule calculations that are also in good agreement with intramolecular vibrations, whereas CASTEP (solid state) results could explain the external modes.
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Affiliation(s)
- Shradhanjali Sahoo
- Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, Tamil Nadu 603102, India
| | - T R Ravindran
- Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, Tamil Nadu 603102, India.
| | - Sharat Chandra
- Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, Tamil Nadu 603102, India
| | - R M Sarguna
- Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, Tamil Nadu 603102, India
| | - B K Das
- Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, Tamil Nadu 603102, India
| | - T N Sairam
- Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, Tamil Nadu 603102, India
| | - V Sivasubramanian
- Materials Science Group, Indira Gandhi Centre for Atomic Research, HBNI, Kalpakkam, Tamil Nadu 603102, India
| | - C Thirmal
- Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu 60036, India
| | - P Murugavel
- Department of Physics, Indian Institute of Technology Madras, Chennai, Tamil Nadu 60036, India
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Ghude SD, Bhat GS, Prabhakaran T, Jenamani RK, Chate DM, Safai PD, Karipot AK, Konwar M, Pithani P, Sinha V, Rao PSP, Dixit SA, Tiwari S, Todekar K, Varpe S, Srivastava AK, Bisht DS, Murugavel P, Ali K, Mina U, Dharua M, Rao J, Padmakumari B, Hazra A, Nigam N, Shende U, Lal DM, Chandra BP, Mishra AK, Kumar A, Hakkim H, Pawar H, Acharja P, Kulkarni R, Subharthi C, Balaji B, Varghese M, Bera S, Rajeevan M. Winter Fog Experiment Over the Indo-Gangetic Plains of India. CURR SCI INDIA 2017. [DOI: 10.18520/cs/v112/i04/767-784] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [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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Abstract
The protective efficacy of diallyl tetrasulfide (DTS) from garlic on liver injury induced by cadmium (Cd) was investigated. In this study, Cd (3 mg/kg body weight) was administered subcutaneously for 3 weeks to induce toxicity. DTS was administered orally (10, 20 and 40 mg/kg body weight) for 3 weeks with subcutaneous (sc) injection of Cd. Cd-induced liver damage was evidenced from increased activities of serum hepatic enzymes, namely aspartate transaminase, alanine transaminase, alkaline phosphatase and lactate dehydrogenase, with significant elevation of lipid peroxidation indices (thiobarbituric acid reactive substances and hydroperoxides) and protein carbonyl groups in the liver. Rats subjected to Cd toxicity also showed a decline in the levels of total thiols, reduced glutathione (GSH), vitamin C and vitamin E, accompanied by an increased accumulation of Cd, and significantly decreased activities of superoxide dismutase, catalase (CAT), glutathione peroxidase, glutathione-S-transferase (GST), glutathione reductase, and glucose-6-phosphate dehydrogenase in the liver. Administration of DTS at 40 mg/kg body weight significantly normalised the activities of hepatic marker enzymes, compared to other doses of DTS (10 and 20 mg/kg body weight). In addition, DTS (40 mg/kg body weight) significantly reduced the accumulation of Cd and the level of lipid peroxidation, and restored the level of antioxidant defense in the liver. Histological studies also showed that administration of DTS to Cd-treated rats resulted in a marked improvement of hepatocytes morphology with mild portal inflammation. Our results suggest that DTS might play a vital role in protecting Cd-induced oxidative damage in the liver. Human & Experimental Toxicology(2007) 26, 527—534
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Affiliation(s)
- P Murugavel
- Department of Biochemistry, Faculty of Science, Annamalai University, Annamalainagar 608002, Tamil Nadu, India
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Tamilselvan A, Balakumar S, Sakar M, Nayek C, Murugavel P, Saravana Kumar K. Role of oxygen vacancy and Fe–O–Fe bond angle in compositional, magnetic, and dielectric relaxation on Eu-substituted BiFeO3 nanoparticles. Dalton Trans 2014; 43:5731-8. [DOI: 10.1039/c3dt52260a] [Citation(s) in RCA: 135] [Impact Index Per Article: 13.5] [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
The influence of oxygen vacancies on the dielectric relaxation behavior of pure and Eu-substituted BiFeO3 nanoparticles synthesized by a sol–gel technique has been studied using impedance spectroscopy in the temperature range of 90 °C to 180 °C.
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Affiliation(s)
- A. Tamilselvan
- National Centre for Nanoscience and Nanotechnology
- University of Madras
- Chennai 600 025, India
| | - S. Balakumar
- National Centre for Nanoscience and Nanotechnology
- University of Madras
- Chennai 600 025, India
| | - M. Sakar
- National Centre for Nanoscience and Nanotechnology
- University of Madras
- Chennai 600 025, India
| | - Chiranjib Nayek
- Department of Physics
- Indian Institute of Technology Madras
- Chennai 600 036, India
| | - P. Murugavel
- Department of Physics
- Indian Institute of Technology Madras
- Chennai 600 036, India
| | - K. Saravana Kumar
- Department of Nuclear Physics
- University of Madras
- Chennai 600 025, India
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Abstract
The toxic effect of chloroquine (CQ) has been attributed to oxidative stress with the consequences of lipid peroxidation. This study investigates the effects of alpha-lipoic acid (LA) on CQ-induced nephrotoxicity in rats. A single oral administration of CQ (970 mg/kg)-induced nephrotoxicity, manifested biochemically by a significant increase in serum creatinine and blood urea nitrogen concentrations. In addition, renal tissue from CQ-treated rats showed a significant increase in lipid peroxides measured as thiobarbituric acid reactive substances and hydroperoxides, along with significant decrease in nonenzymic antioxidants (vitamin C, vitamin E, and reduced glutathione) and enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase, and glutathione-S-transferase) levels. Oral administration of LA (10, 30, or 100 mg/kg) in different doses for 10 days produced a significant protection against nephrotoxicity induced by CQ. Treatment with LA markedly reduced the elevated lipid peroxidation, restored the depleted renal antioxidant defense system. LA at 100 mg/kg was effective when compared with other doses (10 and 30 mg/kg). This was accompanied by the histopathological observations in kidney tissue. The results suggest that LA ameliorate the lipid peroxidation and the loss of cellular antioxidants, thereby protecting the CQ-induced oxidative damage in kidney.
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Affiliation(s)
- P Murugavel
- Department of Biochemistry, Faculty of Science, Annamalai University, Tamil Nadu, India
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Pawar SD, Murugavel P, Lal DM. Effect of relative humidity and sea level pressure on electrical conductivity of air over Indian Ocean. ACTA ACUST UNITED AC 2009. [DOI: 10.1029/2007jd009716] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Cho DY, Kim JY, Park BG, Rho KJ, Park JH, Noh HJ, Kim BJ, Oh SJ, Park HM, Ahn JS, Ishibashi H, Cheong SW, Lee JH, Murugavel P, Noh TW, Tanaka A, Jo T. Ferroelectricity driven by Y d0-ness with rehybridization in YMnO3. Phys Rev Lett 2007; 98:217601. [PMID: 17677806 DOI: 10.1103/physrevlett.98.217601] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2006] [Indexed: 05/16/2023]
Abstract
We investigated electronic structure of hexagonal multiferroic YMnO3 using the polarization dependent x-ray absorption spectroscopy (XAS) at O K and Mn L(2,3) edges. The spectra exhibit strong polarization dependence at both edges, reflecting anisotropic Mn 3d orbital occupation. Moreover, the O K edge spectra show that Y 4d states are strongly hybridized with O 2p ones, resulting in large anomalies in Born effective charges on off-centering Y and O ions. These results manifest that the Y d(0)-ness with rehybridization is the driving force for the ferroelectricity, and suggest a new approach to understand the multiferroicity in the hexagonal manganites.
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Affiliation(s)
- D-Y Cho
- CSCMR & School of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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Abstract
Cadmium (Cd) induces extensive membrane damage that contributes to the cytotoxic effect of Cd. We studied the effect of diallyl tetrasulfide (DTS) from garlic on Cd-induced changes in lipid peroxidation and membrane-bound enzymes in liver, kidney, and testis of rats. Cadmium exposure (3 mg/kg body weight, s.c) for 3 weeks induced a significant elevation in the levels of lipid peroxidation markers (thiobarbituric acid substances and lipid hydroperoxides) with a significant decrease in the activities of membrane bound ATPases (Na+/K+ ATPase, Ca2+ ATPase, Mg2+ ATPase), the indicators of membrane function in liver, kidney and testis. The oral administration of DTS (40 mg/kg body weight) along with Cd significantly decreased the level of lipid peroxidation and significantly restored the activities of membrane bound ATPases. The results of our study suggest that DTS attenuates lipid peroxidation in tissues and promotes the stability of the membrane by protecting it from Cd-induced alterations.
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Affiliation(s)
- P Murugavel
- Department of Biochemistry and Biotechnology, Faculty of Science, Annamalai University, Annamalainagar, Tamil Nadu 608 002, India
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Pari L, Murugavel P, Sitasawad SL, Kumar KS. Cytoprotective and antioxidant role of diallyl tetrasulfide on cadmium induced renal injury: An in vivo and in vitro study. Life Sci 2007; 80:650-8. [PMID: 17125799 DOI: 10.1016/j.lfs.2006.10.013] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2006] [Revised: 10/06/2006] [Accepted: 10/18/2006] [Indexed: 11/29/2022]
Abstract
Cadmium (Cd) is an environmental and industrial pollutant that affects various organs in humans and animals. A body of evidence has accumulated implicating the free radical generation with subsequent oxidative stress in the biochemical and molecular mechanisms of Cd toxicity. Since kidney is the critical target of Cd toxicity, we carried out this study to investigate the effects of diallyl tetrasulfide (DTS), an organosulfur compound derived from garlic on Cd induced toxicity in the kidney of rats and also in the kidney cell line (vero cells). In experimental rats, subcutaneous administration of Cd (3 mg/kg bw/day) for 3 weeks induced renal damage, which was evident from significantly increased levels of serum urea and creatinine with significant decrease in creatinine clearance. A markedly increased levels of lipid peroxidation markers (thiobarbituric acid reactive substances and lipid hydroperoxides) and protein carbonyl contents with significant decrease in nonenzymic antioxidants (total sulphydryl groups, reduced glutathione, vitamin C and vitamin E) and enzymic antioxidants (superoxide dismutase, catalase, glutathione peroxidase and glutathione-S-transferase) as well as glutathione metabolizing enzymes (glutathione reductase, and glucose-6-phosphate dehydrogenase) were also observed in Cd intoxicated rats. Coadministration of DTS (40 mg/kg bw/day) and Cd resulted in the reversal of the kidney function accompanied by a significant decrease in lipid peroxidation and increase in the antioxidant defense system. In vitro studies with vero cells showed that incubation of DTS (5-50 microg/ml) with Cd (10 microM) significantly reduced the cell death induced by Cd. DTS at 40 microg/ml effectively blocked the cell death and lipid peroxidation induced by Cd (10 microM) indicating its cytoprotective property. Further, the flow cytometric assessment on the level of intracellular reactive oxygen species using a fluorescent probe 2', 7'-dichlorofluorescein diacetate (DCF-DA) confirmed the Cd induced intracellular oxidative stress in vero cells, which was significantly suppressed by DTS (40 microg/ml). The histopathological studies in the kidney of rats also showed that DTS (40 mg/kg bw/day) markedly reduced the toxicity of Cd and preserved the architecture of renal tissue. The present study suggests that the cytoprotective potential of DTS in Cd toxicity might be due to its antioxidant and metal chelating properties, which could be useful for achieving optimum effects in Cd induced renal damage.
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Affiliation(s)
- L Pari
- Department of Biochemistry, Faculty of Science, Annamalai University, Annamalainagar -- 608002, Tamilnadu, India.
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Kim MW, Moon SJ, Jung JH, Yu J, Parashar S, Murugavel P, Lee JH, Noh TW. Effect of orbital rotation and mixing on the optical properties of orthorhombic RMnO3 (R=La, Pr, Nd, Gd, and Tb). Phys Rev Lett 2006; 96:247205. [PMID: 16907278 DOI: 10.1103/physrevlett.96.247205] [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] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2005] [Indexed: 05/11/2023]
Abstract
We investigated the ab-plane absorption spectra of RMnO3 (R=La, Pr, Nd, Gd, and Tb) thin films. As the ionic radius of the R ion decreases, we observed a drastic suppression of the 2 eV peak, i.e., the intersite optical transition between spin- and orbital-aligned states across the Mott gap. We found that, in addition to orbital rotation, orbital mixing in the orbital-ordered state should play an important role in the suppression of 2 eV peak. We also found that the spectral weight of 2 eV peak is proportional to the A-type antiferromagnetic ordering temperature, which suggests that the magnetic interaction should be sensitively coupled to the orbital degree of freedom.
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Affiliation(s)
- M W Kim
- ReCOE & School of Physics, Seoul National University, Seoul 151-747, Korea
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Abstract
Oral administration of a-lipoic acid, a metavitamin, was investigated for its possible hepatoprotective effect in Wistar rats against chloroquine-induced toxicity. Rats were treated orally with alpha-lipoic acid (10, 30 and 100 mg x kg(-1) day(-1)) for 7 days before a single oral administration of chloroquine (970 mg x kg(-1) day(-1)) and alpha-lipoic acid treatment was continued for three more days. The increased level of serum enzymes (aspartate transaminase, alanine transaminase and alkaline phosphatase), bilirubin, lipids and plasma thiobarbituric acid-reactive substances (TBARS) and hydroperoxides observed in rats treated with chloroquine were very much reduced in rats treated with alpha-lipoic acid plus chloroquine. A significant decrease in plasma antioxidants such as reduced glutathione (GSH), vitamin C and vitamin E were observed in chloroquine-treated rats when compared with control rats. Administration of alpha-lipoic acid significantly improved the levels of plasma antioxidants GSH, vitamin C and vitamin E in chloroquine-treated rats. In the case of 100 mg x kg(-1) day(-1) the effect was highly significant compared with the other doses (10 and 30 mg x kg(-1) day(-1)). The results of the study revealed that alpha-lipoic acid could offer protection against chloroquine-induced hepatotoxicity. alpha-Lipoic acid had a better protective effect when compared with silymarin, a reference drug.
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Affiliation(s)
- L Pari
- Department of Biochemistry, Faculty of Science, Annamalai University, Annamalai Nagar, Tamil Nadu 608 002, India.
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Ita B, Murugavel P, Ponnambalam V, Raju AR. Magnetic properties of lanthanum orthoferrite fine powders prepared by different chemical routes. J CHEM SCI 2003. [DOI: 10.1007/bf02708243] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [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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Nagaraja K, Prasad B, Madhava M, Chandrashekara M, Paramesh L, Sannappa J, Pawar S, Murugavel P, Kamra A. Radon and its short-lived progeny: variations near the ground. RADIAT MEAS 2003. [DOI: 10.1016/s1350-4487(03)00162-8] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [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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Affiliation(s)
- A. K. Kamra
- Indian Institute of Tropical Meteorology; Pune India
| | - P. Murugavel
- Indian Institute of Tropical Meteorology; Pune India
| | - S. D. Pawar
- Indian Institute of Tropical Meteorology; Pune India
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Kamra AK, Murugavel P, Pawar SD, Gopalakrishnan V. Background aerosol concentration derived from the atmospheric electric conductivity measurements made over the Indian Ocean during INDOEX. ACTA ACUST UNITED AC 2001. [DOI: 10.1029/2001jd900178] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Murugavel P, Kalaiselvam M, Raju AR, Rao CNR. Sub-micrometre spherical particles of TiO2, ZrO2 and PZT by nebulized spray pyrolysis of metal–organic precursors. ACTA ACUST UNITED AC 1997. [DOI: 10.1039/a700301c] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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