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Heron JT, Trassin M, Ashraf K, Gajek M, He Q, Yang SY, Nikonov DE, Chu YH, Salahuddin S, Ramesh R. Electric-field-induced magnetization reversal in a ferromagnet-multiferroic heterostructure. PHYSICAL REVIEW LETTERS 2011; 107:217202. [PMID: 22181917 DOI: 10.1103/physrevlett.107.217202] [Citation(s) in RCA: 112] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Indexed: 05/12/2023]
Abstract
A reversal of magnetization requiring only the application of an electric field can lead to low-power spintronic devices by eliminating conventional magnetic switching methods. Here we show a nonvolatile, room temperature magnetization reversal determined by an electric field in a ferromagnet-multiferroic system. The effect is reversible and mediated by an interfacial magnetic coupling dictated by the multiferroic. Such electric-field control of a magnetoelectric device demonstrates an avenue for next-generation, low-energy consumption spintronics.
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202
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Yokoyama T, Tam J, Kuroda S, Scott AW, Aaron J, Larson T, Shanker M, Correa AM, Kondo S, Roth JA, Sokolov K, Ramesh R. EGFR-targeted hybrid plasmonic magnetic nanoparticles synergistically induce autophagy and apoptosis in non-small cell lung cancer cells. PLoS One 2011; 6:e25507. [PMID: 22087216 PMCID: PMC3210119 DOI: 10.1371/journal.pone.0025507] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Accepted: 09/05/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND The epidermal growth factor receptor (EGFR) is overexpressed in 80% of non-small cell lung cancer (NSCLC) and is associated with poor survival. In recent years, EGFR-targeted inhibitors have been tested in the clinic for NSCLC. Despite the emergence of novel therapeutics and their application in cancer therapy, the overall survival rate of lung cancer patients remains 15%. To develop more effective therapies for lung cancer we have combined the anti-EGFR antibody (Clone 225) as a molecular therapeutic with hybrid plasmonic magnetic nanoparticles (NP) and tested on non-small cell lung cancer (NSCLC) cells. METHODOLOGY/PRINCIPAL FINDINGS Cell viability was determined by trypan-blue assay. Cellular protein expression was determined by Western blotting. C225-NPs were detected by electron microscopy and confocal microscopy, and EGFR expression using immunocytochemistry. C225-NP exhibited a strong and selective antitumor effect on EGFR-expressing NSCLC cells by inhibiting EGFR-mediated signal transduction and induced autophagy and apoptosis in tumor cells. Optical images showed specificity of interactions between C225-NP and EGFR-expressing NSCLC cells. No binding of C225-NP was observed for EGFR-null NSCLC cells. C225-NP exhibited higher efficiency in induction of cell killing in comparison with the same amount of free C225 antibody in tumor cells with different levels of EGFR expression. Furthermore, in contrast to C225-NP, free C225 antibody did not induce autophagy in cells. However, the therapeutic efficacy of C225-NP gradually approached the level of free antibodies as the amount of C225 antibody conjugated per nanoparticle was decreased. Finally, attaching C225 to NP was important for producing the enhanced tumor cell killing as addition of mixture of free C225 and NP did not demonstrate the same degree of cell killing activity. CONCLUSIONS/SIGNIFICANCE We demonstrated for the first time the molecular mechanism of C225-NP induced cytotoxic effects in lung cancer cells that are not characteristic for free molecular therapeutics thus increasing efficacy of therapy against NSCLC.
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Zhang JX, He Q, Trassin M, Luo W, Yi D, Rossell MD, Yu P, You L, Wang CH, Kuo CY, Heron JT, Hu Z, Zeches RJ, Lin HJ, Tanaka A, Chen CT, Tjeng LH, Chu YH, Ramesh R. Microscopic origin of the giant ferroelectric polarization in tetragonal-like BiFeO(3). PHYSICAL REVIEW LETTERS 2011; 107:147602. [PMID: 22107234 DOI: 10.1103/physrevlett.107.147602] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2011] [Indexed: 05/12/2023]
Abstract
We report direct experimental evidence for a room-temperature, ∼130 μC/cm(2) ferroelectric polarization from the tetragonal-like BiFeO(3) phase. The physical origin of this remarkable enhancement of ferroelectric polarization has been investigated by a combination of x-ray absorption spectroscopy, scanning transmission electron microscopy, and first principles calculations. A large strain-induced Fe-ion displacement relative to the oxygen octahedra, combined with the contribution of Bi 6s lone pair electrons, is the mechanism driving the large ferroelectric polarization in this tetragonal-like phase.
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Krishnamoorthy P, Sathyadevi P, Senthilkumar K, Muthiah PT, Ramesh R, Dharmaraj N. Copper(I) hydrazone complexes: Synthesis, structure, DNA binding, radical scavenging and computational studies. INORG CHEM COMMUN 2011. [DOI: 10.1016/j.inoche.2011.05.004] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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205
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Jayakumari VG, Shamsudeen RK, Ramesh R, Mukundan T. Modeling and validation of polyurethane based passive underwater acoustic absorber. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2011; 130:724-730. [PMID: 21877787 DOI: 10.1121/1.3605670] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The acoustic behavior of an acoustically transparent polyurethane and an interpenetrating polymer network of polyurethane with polydimethyl siloxane were studied using dynamic mechanical analysis, finite element modeling, and experimental evaluation of acoustic properties in a water-filled pulse tube setup. Dynamic mechanical measurements in the temperature range -50 °C to +70 °C were carried out, and the data were used for time temperature superposition to generate material behavior at high frequencies. These inputs were used for modeling the acoustic behavior of these materials using ATILA, which is a commercial finite element code, capable of computing transmission and reflection characteristics of materials. From this data, absorption characteristics were computed. The results were compared with the experimental results obtained using a water-filled pulse tube facility.
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Ma LL, Tam JO, Willsey BW, Rigdon D, Ramesh R, Sokolov K, Johnston KP. Selective targeting of antibody conjugated multifunctional nanoclusters (nanoroses) to epidermal growth factor receptors in cancer cells. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2011; 27:7681-90. [PMID: 21591638 PMCID: PMC3242479 DOI: 10.1021/la200659z] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The ability of smaller than 100 nm antibody (Ab) nanoparticle conjugates to target and modulate the biology of specific cell types may enable major advancements in cellular imaging and therapy in cancer. A key challenge is to load a high degree of targeting, imaging, and therapeutic functionality into small, yet stable particles. A versatile method called thin autocatalytic growth on substrate (TAGs) has been developed in our previous study to form ultrathin and asymmetric gold coatings on iron oxide nanocluster cores producing exceptional near-infrared (NIR) absorbance. AlexaFluor 488 labeled Abs were used to correlate the number of Abs conjugated to iron oxide/gold nanoclusters (nanoroses) with the hydrodynamic size. A transition from submonolayer to multilayer aggregates of Abs on the nanorose surface was observed for 54 Abs and an overall particle diameter of ∼60-65 nm. The hydrodynamic diameter indicated coverage of a monolayer of 54 Abs, in agreement with the prediction of a geometric model, by assuming a circular footprint of 16.9 nm diameter per Ab molecule. The targeting efficacy of nanoclusters conjugated with monoclonal Abs specific for epidermal growth factor receptor (EGFR) was evaluated in A431 cancer cells using dark field microscopy and atomic absorbance spectrometry (AAS) analysis. Intense NIR scattering was achieved from both high uptake of nanoclusters in cells and high intrinsic NIR absorbance of individual nanoclusters. Dual mode imaging with dark field reflectance microscopy and fluorescence microscopy indicates the Abs remained attached to the Au surfaces upon the uptake by the cancer cells. The ability to load intense multifunctionality, specifically strong NIR absorbance, conjugation of an Ab monolayer in addition to a strong r2 MRI contrast that was previously demonstrated in a total particle size of only 63 nm, is an important step forward in development of theranostic agents for combined molecular specific imaging and therapy.
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Sundarapandiyan S, Brutto PE, Siddhartha G, Ramesh R, Ramanaiah B, Saravanan P, Mandal AB. Enhancement of chromium uptake in tanning using oxazolidine. JOURNAL OF HAZARDOUS MATERIALS 2011; 190:802-809. [PMID: 21536383 DOI: 10.1016/j.jhazmat.2011.03.117] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2010] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 05/30/2023]
Abstract
Monocyclic and bicyclic oxazolidines were offered at three different junctures of chrome tanning process viz. prior to BCS offer, along with BCS and after basification. It was found that oxazolidine when offered after basification brought about better chromium uptake and reduction of chromium load in the wastewater. Offer of oxazolidine was also varied. Increase in offer of oxazolidine from 0.25% to 1% was found to enhance the chromium uptake and decrease the chromium load in wastewater. But the increase in uptake was not proportionate to the increase in oxazolidine offer more than 0.75%. Offer of 1% Zoldine ZA 78 (monocyclic oxazolidine) and Zoldine ZE (bicyclic oxazolidine) after basification brought about 63.4% and 73.1% enhancement in chrome content in leather compared to control where oxazolidine was not offered. The tone of the wetblue was found to be altered moderately. However this did not call for any process adjustments in wet-finishing. The oxazolidine treated leathers were found to be immensely fuller and tighter. It was found experimentally that offer of 1% of oxazolidine facilitated reduction in the offer of syntans administered for filling and grain tightening by around 46%. Oxazolidine could bring about significant reduction in cost of chemicals apart from resulting environmental benefits due to enhancement of chromium uptake during tanning.
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Du AY, Das S, Gopal RD, Ramesh R. Risk hedging in storage grid markets. ACM TRANSACTIONS ON MANAGEMENT INFORMATION SYSTEMS 2011. [DOI: 10.1145/1985347.1985351] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Internet storage services allow businesses to move away from maintaining their own internal storage networks. Service providers currently follow a utility pricing model which translates to them absorbing all the risk that arises from the fluctuating storage needs of their customers. The risk borne by the Internet storage service providers has large revenue implications as Internet startups and smaller companies, which face significant demand stochasticity, constitute an important segment of their clientele. We develop an option pricing mechanism to hedge against this risk and evaluate its effectiveness vis-à-vis forward contracts. We obtain the conditions under which options dominate forward contracts and the trade-offs involved when the provider has to decide on appropriate pricing mechanisms. Our empirical study uses publicly obtainable traffic data of Amazon S3 clients to validate the analytical results. We show that providers can significantly benefit from including options in their risk-hedging portfolio, especially when there is less variation in the costs faced by the buyers in building their own data networks as opposed to using cloud services.
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209
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Zhou SY, Zhu Y, Langner MC, Chuang YD, Yu P, Yang WL, Cruz Gonzalez AG, Tahir N, Rini M, Chu YH, Ramesh R, Lee DH, Tomioka Y, Tokura Y, Hussain Z, Schoenlein RW. Ferromagnetic enhancement of CE-type spin ordering in (Pr,Ca)MnO3. PHYSICAL REVIEW LETTERS 2011; 106:186404. [PMID: 21635110 DOI: 10.1103/physrevlett.106.186404] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Indexed: 05/30/2023]
Abstract
We present resonant soft x-ray scattering results from small bandwidth manganites (Pr,Ca)MnO(3), which show that the CE-type spin ordering (SO) at the phase boundary is stabilized only below the canted antiferromagnetic transition temperature and enhanced by ferromagnetism in the macroscopically insulating state (FM-I). Our results reveal the fragility of the CE-type ordering that underpins the colossal magnetoresistance effect in this system, as well as an unexpected cooperative interplay between FM-I and CE-type SO which is in contrast to the competitive interplay between the ferromagnetic metallic state and CE-type ordering.
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Mandal PK, Gao F, Lu Z, Ren Z, Ramesh R, Birtwistle JS, Kaluarachchi KK, Chen X, Bast RC, Liao WS, McMurray JS. Potent and selective phosphopeptide mimetic prodrugs targeted to the Src homology 2 (SH2) domain of signal transducer and activator of transcription 3. J Med Chem 2011; 54:3549-63. [PMID: 21486047 DOI: 10.1021/jm2000882] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Signal transducer and activator of transcription 3 (Stat3), a target for anticancer drug design, is activated by recruitment to phosphotyrosine residues on growth factor and cytokine receptors via its SH2 domain. We report here structure-activity relationship studies on phosphopeptide mimics targeted to the SH2 domain of Stat3. Inclusion of a methyl group on the β-position of the pTyr mimic 4-phosphocinnamide enhanced affinity 2- to 3-fold. Bis-pivaloyloxymethyl prodrugs containing β-methylcinnamide, dipeptide scaffolds Haic and Nle-cis-3,4-methanoproline, and glutamine surrogates were highly potent, completely inhibiting phosphorylation of Stat3 Tyr705 at 0.5-1 μM in a variety of cancer cell lines. The inhibitors were selective for Stat3 over Stat1, Stat5, Src, and p85 of PI3K, indicating ability to discriminate individual SH2 domains in intact cells. At concentrations that completely inhibited Stat3 phosphorylation, the prodrugs were not cytotoxic to a panel of tumor cells, thereby showing clear distinction between cytotoxicity and effects downstream of activated Stat3.
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211
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Lu C, Stewart DJ, Ji L, Ramesh R, Jayachandran G, Nunez MI, Wistuba II, Erasmus JJ, Lee JJ, McMannis JD, Templeton NS, Roth JA. Abstract 5391: Systemic gene therapy with tumor suppressor TUSC2/FUS1 nanoparticles for recurrent/metastatic lung cancer. Cancer Res 2011. [DOI: 10.1158/1538-7445.am2011-5391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Background: The tumor suppressor gene TUSC2/FUS1 (TUSC2) is frequently inactivated early in lung cancer development. TUSC2 mediates apoptosis in cancer cells but not normal cells by upregulation of the Apaf-1-dependent apoptotic pathway. DOTAP:cholesterol nanoparticles encapsulating a TUSC2 expression plasmid (DOTAP:chol-TUSC2) showed preferential uptake by cancer cells and prolonged survival in mouse xenograft metastatic lung cancer models.
Methods: Patients with recurrent and/or metastatic lung cancer previously treated with platinum-based chemotherapy were treated with escalating doses of intravenous DOTAP:chol-TUSC2 every 3 weeks. The primary end point was assessment of DOTAP:chol-TUSC2 toxicity and determination of the MTD. TUSC2 plasmid expression in pretreatment and 24 hour posttreatment tumor specimens from subjects consenting to tumor biopsies was analyzed with quantitative RT-PCR analysis using a TUSC2 plasmid sequence-specific probe, in situ proximity ligation assay for TUSC2 protein, and apoptosis signaling nanoscale PCR array.
Results: Thirty-one patients were treated at 6 dose levels ranging from 0.01 to 0.09 mg/kg and 7 had paired pre- and posttreatment biopsies. RT-PCR analysis detected high TUSC2 plasmid expression in 6 of 7 posttreatment tumor specimens but not in pretreatment specimens and negative controls. Immunohistochemical staining has been performed on 1 paired specimen, demonstrating low background TUSC2 protein staining in the pretreatment tissue compared with high intense TUSC2 protein staining in the posttreatment tissue. RT-PCR gene expression profiling analysis of apoptotic pathway genes in one paired specimen demonstrated significant upregulation and downregulation of genes involved in both the intrinsic and extrinsic apoptotic pathways. Among 4 patients treated without premedications, all 4 developed grade 2 or 3 fever. Among the 27 patients premedicated with dexamethasone and diphenhydramine, the highest fever was grade 2, which occurred in 2 subjects. The only dose-limiting toxicities were 2 episodes of transient grade 3 hypophosphatemia, resulting in an MTD of 0.06 mg/kg. Twenty-three patients who received 2 or more doses were evaluable for response, with 5 achieving stable disease (2.6-10.8 months) and 18 progressing. One patient with stable disease had evidence of a durable metabolic response on positron emission tomography imaging. The pretreatment apoptotic index was predictive of disease stability. Median survival time was 9.1 months. Conclusions: DOTAP:chol-TUSC2 can be safely administered intravenously in lung cancer patients and results in demonstrable gene and protein expression in tumors. It appears to regulate apoptotic pathway genes with evidence of antitumor activity. The MTD for phase II testing is 0.06 mg/kg every 3 weeks. Based on promising preclinical data, a trial in combination with erlotinib is planned.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5391. doi:10.1158/1538-7445.AM2011-5391
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Li Y, Efferson CL, Ramesh R, Peoples GE, Hwu P, Ioannides CG. A peptidoglycan monomer with the glutamine to serine change and basic peptides bind in silico to TLR-2 (403-455). Cancer Immunol Immunother 2011; 60:515-24. [PMID: 21188584 PMCID: PMC11028711 DOI: 10.1007/s00262-010-0959-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2010] [Accepted: 12/08/2010] [Indexed: 12/30/2022]
Abstract
Bacterial cell wall polysaccharides, such as PGN, bind and activate TLR-2, NOD2 and PGRP on monocytes/macrophages and activate inflammation. We found that the peptides containing basic amino acids (cations) at N -terminus and tyrosine at C-terminus interfered with activating ability of PGN. This finding is significant because the ECD of TLR-2 in vivo encounters a large number of proteins or peptides. Some should bind ECD and "pre-form" TLR-2 to respond or not to its activators, although they cannot activate TLR-2 alone. TLR-2 is receptor for a large number of ligands, including lipopeptides and bacterial cell wall glycoproteins. A binding site for lipopeptides has been identified; however, a binding site for soluble or multimeric PGN has not been proposed. To identify the candidate binding sites of peptides and PGN on TLR-2, we modeled docking of peptides and of the PGN monomer (PGN-S-monomer) to extracellular domain (ECD-TLR-2) of the unbound TLR-2. Quantification, in silico, of free energy of binding (DG) identified 2 close sites for peptides and PGN. The PGN-S-monomer binding site is between amino acids TLR-2, 404-430 or more closely TLR-2, 417-428. The peptide-binding site is between amino acids TLR-2, 434-455. Molecular models show PGN-S-monomer inserts its N -acetyl-glucosamine (NAG) deep in the TLR-2 coil, while its terminal lysine interacts with inside (Glu(403)) and outside pocket (Tyr(378)). Peptides insert their two N -terminal arginines or their C-terminal tyrosines in the TLR-2 coil. PGN did not bind the lipopeptide-binding site in the TLR-2. It can bind the C-terminus, 572-586 (DG = 0.026 kcal), of "lipopeptide-bound" TLR-2. An additional, low-affinity PGN-binding site is TLR-2 (227-237). MTP, MDP, and lysine-less PGN bind to TLR-2, 87-113. This is the first report identifying candidate binding sites of monomer PGN and peptides on TLR-2. Experimental verification of our findings is needed to create synthetic adjuvant for vaccines. Such synthetic PGN can direct both adjuvant and cancer antigen to TLR-2.
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Ganpule CS, Roytburd AL, Nagarajan V, Stanishevsky A, Melngailis J, Williams ED, Ramesh R. Nanoscale electromechanical phenomena in ferroelectric thin films. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-655-cc1.5.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractFocused ion beam milling was used to fabricate ferroelectric islands in Pb-Zr-Ti-O thin films. The islands ranged in size from 200μm×200μm to 0.3μm×0.3μm. The inverse piezoelectric effect was studied in these islands as a function of their size by tracking the surface displacement of the top electrode of the island (under an applied electric field) using an atomic force microscope (AFM). It was found that there was a substantial increase in the piezoresponse as the size of the island decreased below 100μm×100μm. This increase was attributed to the elastic deformation of the substrate.
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214
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Sands T, Harbison J, Palmstrøm C, Ramesh R, Keramidas V. A Template Approach to Metal/III-V Semiconductor Epitaxy. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-221-271] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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215
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Tarascon JM, LePage Y, McKinnon WR, Tselepis E, Barboux P, Bagley B, Ramesh R. On the Origin of the Structural Modulation in the Bi Cuprates As Derived from 3d-Metal Substituted Phases. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-156-317] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTA substitution for Cu by a 3d-metal (Fe, Co, Mn) in the superconducting Bi phases (Bi2Sr2Can−1CunOy; n = 1,2 and 3) has led to the discovery of new phases. These 3d-metal substituted phases are non-superconducting and, in contrast to the Cu-based phases, they exhibit a structural modulation that is commensurate. Single crystal x-ray studies were performed on the Bi2Sr3Fe2Oy, Bi2Sr2CoOy and Bi2Sr2MnOy compounds. A result, in common, is that the modulation is caused by the periodic insertion of a row of oxygen atoms in the Bi layers and this results in a corrugated-like slab structure. The Bi-O layers can be described as composed of alternating rocksalt-type and oxygen deficient perovskite-type blocks. For the Fe (n=2) phase the Bi atoms form ribbons (chains) in the ab plane. This is in contrast to the n=1 Co or Mn phases for which a disorder at the oxygen position is observed. Although the extra oxygen in the Bi-O layer could account for the doping mechanism in the high Tc Bi-phases, cation non-stoichiometry may also beimportant.
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216
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Wu XD, Venkatesan T, Inam A, Xi XX, Li Q, McLean WL, Chang CC, Hwang DM, Ramesh R, Nazar L, Wilkens B, Schwarz SA, Ravi RT, Martinez JA, England P, Tarascon JM, Muenchausen RE, Foltyn S, Estler RC, Dye RC, Garcia AR, Nogar NS. Pulsed Laser Deposition of High Tc Superconducting thin Films: Present and Future. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-191-129] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTPulsed laser deposition (PLD) has been widely used for deposition of high Tc superconducting thin films, and is recognized as one of the best physical vapor techniques for the preparation of these films. The most important advantage of this technique is stoichiometric deposition; films can be made with the same composition as the target. Utilizing PLD, not only thin films but also multilayers and superlattices of high Tc superconductors have been fabricated. In this paper, the performance of the technique will be reviewed, and speculations regarding the future would be made.
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217
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Warren WL, Dimos D, Tuttle BA, Pike GE, Raymond MV, Nasby RD, Ramesh R, Evans JT. Mechanism(s) for the Suppression of the Switchable Polarization in PZT and BaTiO3. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-361-51] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTSwitchable polarization can be significantly suppressed in ferroelectric (FE) materials by optical, thermal, and electrical processes. The thermal process can occur by either annealing the FE in a reducing environment or by heating it in air to 100°C while impressing a bias near the switching threshold. The optical process occurs while biasing the FE near the switching threshold and illuminating with bandgap light. And the electrical suppression effect occurs by subjecting the FE to repeated polarization reversals. Using electron paramagnetic resonance, polarization-vol tage measurements, and charge injection scenarios, we have been able to elucidate both electronic and ionic trapping effects that lead to a suppression in the amount of switchable polarization in FE materials. The relative roles of electronic and ionic effects in the same material can depend on the stress condition. For instance, in oxidized BaTiO3 crystals, optical and thermal suppressions occur by electronic domain pinning; electrical fatigue in the BaTiO3 crystals also appears to involve electronic charge trapping, however, it is suggested that these electronic traps are further stabilized by nearby ionic defects. In sol-gel PZT thin films with either Pt, RuO2, or La-Sr-Co-O electrodes it appears that the polarization suppression induced by electrical fatigue, a temperature/bias combination, or a light/bias combination are all primarily due to the trapping of electronic charge carriers to first order.
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Eatough MO, Dimos D, Tuttle BA, Warren WL, Ramesh R. A Study of Switching Behavior in Pb(Zr,Ti) O3 Thin Films Using X-Ray Diffraction. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-361-111] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTPb(Zr,Ti)O3 (PZT) thin films are being developed for use in optical and electronic memory devices. To study ferroelectric switching behavior, we have produced relatively untextured PZT thin films on Si substrates. We have developed a method for using x-ray diffraction to observe domain switching in situ. Our study involved the use of a micro-diffractometer to monitor the switching behavior in relatively small (0.7mm diameter) electroded areas. Diffraction analyses were done while DC voltages were applied and removed, representing several places in the hysteresis loop. In particular, we were looking for relative intensity changes in the [h 00],[00l] diffraction peaks as a function of position in the hysteresis loop. Our study indicates that the 90° domain switching exhibited by bulk ferroelectrics, is very limited in films on Si when grain sizes are less than about 1 μm.
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Alpay SP, Prakash AS, Aggarwal S, Ramesh R, Roytburd AL, Shuk P, Greenblatt M. Polydomain Structure of Epitaxial PbTiO3 films on MgO. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-493-111] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTA PbTiO3(001) film grown on MgO(001) by pulsed laser deposition is examined as an example to demonstrate the applications of the domain stability map for epitaxial perovskite films which shows regions of stable domains and fractions of domains in a polydomain structure. X-ray diffraction studies indicate that the film has a …c/a/c/a… domain structure in a temperature range of °C to 400°C with the fraction of c-domains decreasing with increasing temperature. These experimental results are in excellent agreement with theoretical predictions based on the stability map.
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220
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Gruverman A, Prakash SA, Aggarwal S, Ramesh R, Auciello O, Tokumoto H. Nanoscale Investigation of Polarization Retention Loss in Ferroelectric Thin Films VIA Scanning Force Microscopy. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-493-53] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTScanning force microscopy (SFM) was applied to direct nanoscale investigation of the mechanism of retention loss in ferroelectric thin films. Experiments were conducted by performing local polarization reversal within an individual grain with subsequent imaging of a resulting domain structure at various time intervals. A conductive SFM tip was used for domain switching and imaging in the SFM piezoresponse mode.
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Zhang JX, Xiang B, He Q, Seidel J, Zeches RJ, Yu P, Yang SY, Wang CH, Chu YH, Martin LW, Minor AM, Ramesh R. Large field-induced strains in a lead-free piezoelectric material. NATURE NANOTECHNOLOGY 2011; 6:98-102. [PMID: 21240285 DOI: 10.1038/nnano.2010.265] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2010] [Accepted: 11/30/2010] [Indexed: 05/30/2023]
Abstract
Piezoelectric materials exhibit a mechanical response to electrical inputs, as well as an electrical response to mechanical inputs, which makes them useful in sensors and actuators. Lead-based piezoelectrics demonstrate a large mechanical response, but they also pose a health risk. The ferroelectric BiFeO(3) is an attractive alternative because it is lead-free, and because strain can stabilize BiFeO(3) phases with a structure that resembles a morphotropic phase boundary. Here we report a reversible electric-field-induced strain of over 5% in BiFeO(3) films, together with a characterization of the origins of this effect. In situ transmission electron microscopy coupled with nanoscale electrical and mechanical probing shows that large strains result from moving the boundaries between tetragonal- and rhombohedral-like phases, which changes the phase stability of the mixture. These results demonstrate the potential of BiFeO(3) as a substitute for lead-based materials in future piezoelectric applications.
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Lee JS, Arena DA, Yu P, Nelson CS, Fan R, Kinane CJ, Langridge S, Rossell MD, Ramesh R, Kao CC. Hidden magnetic configuration in epitaxial La(1-x) Sr(x) MnO3 films. PHYSICAL REVIEW LETTERS 2010; 105:257204. [PMID: 21231622 DOI: 10.1103/physrevlett.105.257204] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2010] [Indexed: 05/30/2023]
Abstract
We present an unreported magnetic configuration in epitaxial La(1-x) Sr(x) MnO3 (x ∼ 0.3) (LSMO) films grown on strontium titanate (STO). X-ray magnetic circular dichroism indicates that the remanent magnetic state of thick LSMO films is opposite to the direction of the applied magnetic field. Spectroscopic and scattering measurements reveal that the average Mn valence varies from mixed Mn(3+)/Mn(4+) to an enriched Mn3+ region near the STO interface, resulting in a compressive lattice along the a, b axis and a possible electronic reconstruction in the Mn e(g) orbital (d(3)z(2)-r(2). This reconstruction may provide a mechanism for coupling the Mn3+ moments antiferromagnetically along the surface normal direction, and in turn may lead to the observed reversed magnetic configuration.
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Seidel J, Maksymovych P, Batra Y, Katan A, Yang SY, He Q, Baddorf AP, Kalinin SV, Yang CH, Yang JC, Chu YH, Salje EKH, Wormeester H, Salmeron M, Ramesh R. Domain wall conductivity in La-doped BiFeO3. PHYSICAL REVIEW LETTERS 2010; 105:197603. [PMID: 21231197 DOI: 10.1103/physrevlett.105.197603] [Citation(s) in RCA: 106] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2010] [Indexed: 05/30/2023]
Abstract
The transport physics of domain wall conductivity in La-doped bismuth ferrite (BiFeO3) has been probed using variable temperature conducting atomic force microscopy and piezoresponse force microscopy in samples with arrays of domain walls in the as-grown state. Nanoscale current measurements are investigated as a function of bias and temperature and are shown to be consistent with distinct electronic properties at the domain walls leading to changes in the observed local conductivity. Our observation is well described within a band picture of the observed electronic conduction. Finally, we demonstrate an additional degree of control of the wall conductivity through chemical doping with oxygen vacancies, thus influencing the local conductive state.
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Laxmi Priya S, Senthilkumar B, Hariharan G, Paneer Selvam A, Purvaja R, Ramesh R. Bioaccumulation of heavy metals in mullet (Mugil cephalus) and oyster (Crassostrea madrasensis) from Pulicat lake, south east coast of India. Toxicol Ind Health 2010; 27:117-26. [DOI: 10.1177/0748233710381892] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The accumulation of six heavy metals (Cr, Cd, Cu, Zn, Pb and Ni) in sediment, water and in tissue parts of Mugil cephalus and Crassostrea madrasensis was studied in two locations of Pulicat lake, Southeast coast of India, which receives considerable quantity of effluents from industries located in North Chennai coastal region. The results reveal that the metal concentration in water is decreasing in the following order of Zn > Ni > Cu > Cr > Pb > Cd both in lake and barmouth and highest concentration was observed for Zn (32.5 μg L-1 in lake and 25.2 μg L-1 in bar mouth). Metals were highly concentrated in sediments when compared to water and biota. Metals abundance in sediments has following sequential order of Cr > Ni > Zn > Cu > Pb > Cd and the accumulation pattern in barmouth showed minor variation indicating the following pattern of Zn > Ni > Cr > Cu > Pb > Cd. The geoaccumulation index (Igeo) for Pulicat lake sediments indicate that the sediments are extremely contaminated with Cd and moderately contaminated with Cu and Ni. Bioaccumulation of heavy metals in Mugil cephalus and Crassostrea madrasensis showed marked differences in the accumulation patterns. It is observed that Zn, Cu and Pb are accumulated in elevated concentrations in various parts of the fish and oyster when compared with other metals.
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Chidambaram S, Ramanathan A, Prasanna MV, Karmegam U, Dheivanayagi V, Ramesh R, Johnsonbabu G, Premchander B, Manikandan S. Study on the hydrogeochemical characteristics in groundwater, post- and pre-tsunami scenario, from Portnova to Pumpuhar, southeast coast of India. ENVIRONMENTAL MONITORING AND ASSESSMENT 2010; 169:553-568. [PMID: 19859821 DOI: 10.1007/s10661-009-1196-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2009] [Accepted: 10/09/2009] [Indexed: 05/28/2023]
Abstract
Natural hazards cause great damage to humankind and the surrounding ecosystem. They can cast certain indelible changes on the natural system. One such tsunami event occurred on 26 December 2004 and caused serious damage to the environment, including deterioration of groundwater quality. This study addresses the groundwater quality variation before and after the tsunami from Pumpuhar to Portnova in Tamil Nadu coast using geochemical methods. As a part of a separate Ph.D. study on the salinity of groundwater from Pondicherry to Velankanni, water quality of this region was studied with the collection of samples during November 2004, which indicated that shallow aquifers were not contaminated by sea water in certain locations. These locations were targeted for post-tsunami sample collection during the months of January, March and August 2005 from shallow aquifers. Significant physical mixing (confirmed with mixing models) within the aquifer occurred during January 2005, followed by precipitation of salts in March and complete leaching and dissolution of these salts in the post-monsoon season of August. As a result, maximum impact of tsunami water was observed in August after the onset of monsoon. Tsunami water inundated inland water bodies and topographic lows where it remained stagnant, especially in the near-shore regions. Maximum tsunami inundation occurred along the fluvial distributary channels, and it was accelerated by topography to a certain extent where the southern part of the study area has a gentler bathymetry than the north.
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Sowmya M, Senthilkumar B, Seshan BRR, Hariharan G, Purvaja R, Ramkumar S, Ramesh R. Natural radioactivity and associated dose rates in soil samples from Kalpakkam, South India. RADIATION PROTECTION DOSIMETRY 2010; 141:239-247. [PMID: 20522563 DOI: 10.1093/rpd/ncq169] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The activity concentration of naturally occurring radioactive elements such as 226Ra, 232Th and 40K were measured for 46 soil samples collected in the vicinity of the Madras atomic power station, Kalpakkam, South India using gamma-ray spectroscopy. The average activity concentration of 226Ra, 232Th and 40K in soil samples were found to be 22.6 ± 12.6, 92.8 ± 44.3 and 434.1 ± 131.1 Bq kg(-1), respectively. The activity concentration of natural radionuclides is higher than the world average except for (226)Ra. The external absorbed gamma dose rates due to 226Ra, 232Th and 40K are observed to be 74.6 ± 30.8 nGy h(-1) with a corresponding annual effective dose of 91.5 ± 37.8 µSv y(-1), which are also above the world average. The values of radium equivalent activity and external hazard index are less than the world average. Whereas, the values of the radioactivity level index (I(γ)) and the total gamma dose rate were found to be above the required criterion.
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Sampath kumar R, Alagumurthi N, Ramesh R. Integrated total cost and Tolerance Optimization with Genetic Algorith. INT J COMPUT INT SYS 2010. [DOI: 10.1080/18756891.2010.9727703] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
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228
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Wu SM, Cybart SA, Yu P, Rossell MD, Zhang JX, Ramesh R, Dynes RC. Reversible electric control of exchange bias in a multiferroic field-effect device. NATURE MATERIALS 2010; 9:756-61. [PMID: 20657590 DOI: 10.1038/nmat2803] [Citation(s) in RCA: 175] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Accepted: 06/14/2010] [Indexed: 05/12/2023]
Abstract
Electric-field control of magnetization has many potential applications in magnetic memory storage, sensors and spintronics. One approach to obtain this control is through multiferroic materials. Instead of using direct coupling between ferroelectric and ferromagnetic order parameters in a single-phase multiferroic material, which only shows a weak magnetoelectric effect, a unique method using indirect coupling through an intermediate antiferromagnetic order parameter can be used. In this article, we demonstrate electrical control of exchange bias using a field-effect device employing multiferroic (ferroelectric/antiferromagnetic) BiFeO(3) as the dielectric and ferromagnetic La(0.7)Sr(0.3)MnO(3) as the conducting channel; we can reversibly switch between two distinct exchange-bias states by switching the ferroelectric polarization of BiFeO(3). This is an important step towards controlling magnetization with electric fields, which may enable a new class of electrically controllable spintronic devices and provide a new basis for producing electrically controllable spin-polarized currents.
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Ramesh Babu R, Ramesh R, Gopalakrishnan R, Ramamurthi K, Bhagavannarayana G. Growth, structural, spectral, mechanical and optical properties of pure and metal ions doped sulphamic acid single crystals. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 76:470-475. [PMID: 20493763 DOI: 10.1016/j.saa.2010.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2009] [Revised: 03/29/2010] [Accepted: 04/08/2010] [Indexed: 05/29/2023]
Abstract
Bulk single crystals of pure and metal ions (Mn(2+), Cu(2+) and Ni(2+)) doped sulphamic acid (SA) have been grown by conventional and unidirectional solution growth methods. Intensities of powder X-ray diffraction peaks of metal ions doped SA reveal that these dopants enhanced the crystallanity. The peak broadening and intensity variation in some frequency regions in FT-IR spectra show the incorporation of dopants in the SA lattice. Mn(2+) and Cu(2+) doped SA single crystals show high crystalline perfection (FWHM 5.5arcs) compared to pure and Ni(2+) metal ions doped SA crystals. The grown pure and Mn(2+), Cu(2+) and Ni(2+) ions doped SA crystals have transparency in the order SA>Mn:SA>Cu:SA>Ni:SA. The hardness value of Ni(2+) doped crystal is relatively less than that of the pure and other metal ions doped SA crystals. Pure and Ni(2+) ions doped SA crystals possess high dielectric constants than that of Cu(2+) and Mn(2+) ions doped crystals. From the SEM micrograph analyses, it is observed that the doping of these metal ions modify the surface morphology of the grown crystals.
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230
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Borisevich AY, Chang HJ, Huijben M, Oxley MP, Okamoto S, Niranjan MK, Burton JD, Tsymbal EY, Chu YH, Yu P, Ramesh R, Kalinin SV, Pennycook SJ. Suppression of octahedral tilts and associated changes in electronic properties at epitaxial oxide heterostructure interfaces. PHYSICAL REVIEW LETTERS 2010; 105:087204. [PMID: 20868130 DOI: 10.1103/physrevlett.105.087204] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2010] [Indexed: 05/29/2023]
Abstract
Epitaxial oxide interfaces with broken translational symmetry have emerged as a central paradigm behind the novel behaviors of oxide superlattices. Here, we use scanning transmission electron microscopy to demonstrate a direct, quantitative unit-cell-by-unit-cell mapping of lattice parameters and oxygen octahedral rotations across the BiFeO3-La0.7 Sr0.3 MnO3 interface to elucidate how the change of crystal symmetry is accommodated. Combined with low-loss electron energy loss spectroscopy imaging, we demonstrate a mesoscopic antiferrodistortive phase transition near the interface in BiFeO3 and elucidate associated changes in electronic properties in a thin layer directly adjacent to the interface.
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231
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Yu P, Lee JS, Okamoto S, Rossell MD, Huijben M, Yang CH, He Q, Zhang JX, Yang SY, Lee MJ, Ramasse QM, Erni R, Chu YH, Arena DA, Kao CC, Martin LW, Ramesh R. Interface ferromagnetism and orbital reconstruction in BiFeO3-La(0.7)Sr(0.3)MnO3 heterostructures. PHYSICAL REVIEW LETTERS 2010; 105:027201. [PMID: 20867733 DOI: 10.1103/physrevlett.105.027201] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Indexed: 05/12/2023]
Abstract
We report the formation of a novel ferromagnetic state in the antiferromagnet BiFeO3 at the interface with ferromagnet La(0.7)Sr(0.3)MnO3. Using x-ray magnetic circular dichroism at Mn and Fe L(2,3) edges, we discovered that the development of this ferromagnetic spin structure is strongly associated with the onset of a significant exchange bias. Our results demonstrate that the magnetic state is directly related to an electronic orbital reconstruction at the interface, which is supported by the linearly polarized x-ray absorption measurement at the oxygen K edge.
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Ramesh R, Ashok K, Bhalero GM, Ponnusamy S, Muthamizhchelvan C. Synthesis and properties of α-Fe2O3 nanorods. CRYSTAL RESEARCH AND TECHNOLOGY 2010. [DOI: 10.1002/crat.201000140] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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233
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Jin S, Tiefel TH, McCormack M, Fastnacht RA, Ramesh R, Chen LH. Thousandfold change in resistivity in magnetoresistive la-ca-mn-o films. Science 2010; 264:413-5. [PMID: 17836905 DOI: 10.1126/science.264.5157.413] [Citation(s) in RCA: 626] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
A negative isotropic magnetoresistance effect more than three orders of magnitude larger than the typical giant magnetoresistance of some superlattice films has been observed in thin oxide films of perovskite-like La(0.67)Ca(0.33)MnOx. Epitaxial films that are grown on LaAIO(3) substrates by laser ablation and suitably heat treated exhibit magnetoresistance values as high as 127,000 percent near 77 kelvin and approximately 1300 percent near room temperature. Such a phenomenon could be useful for various magnetic and electric device applications if the observed effects of material processing are optimized. Possible mechanisms for the observed effect are discussed.
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Lu C, Stewart DJ, Ji L, Ramesh R, Jayachandran G, Erasmus JJ, Lee J, Templeton NS, McMannis JD, Roth JA. Systemic gene therapy with tumor suppressor FUS1-nanoparticles for recurrent/metastatic lung cancer. J Clin Oncol 2010. [DOI: 10.1200/jco.2010.28.15_suppl.7582] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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235
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Shanker M, Willcutts D, Roth JA, Ramesh R. Drug resistance in lung cancer. LUNG CANCER (AUCKLAND, N.Z.) 2010; 1:23-36. [PMID: 28210104 PMCID: PMC5312467] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Resistance to chemotherapy drugs is a major problem in cancer treatment. Scientific advances made in the last two decades have resulted in the identification of genes and molecular signaling mechanisms that contribute to drug resistance. This has resulted in a better understanding of the biology of cancer cells and the way these cells adapt or undergo subtle molecular changes thereby protecting themselves from the cytotoxic effects of the anticancer drugs. Based on the knowledge gained to-date new molecularly targeted drugs are being developed and tested in clinical studies, in an attempt to overcome drug resistance and improve drug efficacy. Despite these attempts the overall 5-year survival of patients diagnosed with cancer, such as lung cancer, remains dismal and is less than 15%. It is evident that additional mechanisms contributing to drug resistance exist which are yet to be discovered. It is hoped that identification of new targets and understanding their contribution to drug resistance will provide opportunities for innovative therapies in overcoming drug resistance. In an attempt to broaden our knowledge and understanding on drug resistance we have, in this review article, summarized the most common mechanisms associated with drug resistance in lung cancer.
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Ulaganatha Raja M, Gowri N, Liu Y, Ramesh R. Erratum to “Synthesis, crystal structure and catalytic activity of ruthenium(II) carbonyl complexes containing ONO and ONS donor ligands” [Polyhedron 29 (2010) 3]. Polyhedron 2010. [DOI: 10.1016/j.poly.2010.03.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Kuroda S, Yokoyama T, Tam J, Scott AW, Shanker M, Correa AM, Roth JA, Sokolov K, Ramesh R. Abstract 3505: EGFR-targeted hybrid plasmonic magnetic nanoparticles induce autophagy and apoptosis through DNA damage in non-small cell lung cancer cells. Cancer Res 2010. [DOI: 10.1158/1538-7445.am10-3505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Nanoparticles represent a novel class of agents for cancer treatment. In the present study, we examined the effects of epidermal growth factor receptor (EGFR)-targeted hybrid plasmonic magnetic nanoparticles (NP) on non-small cell lung cancer (NSCLC) cells. The nanoparticles (NP) consisted of a paramagnetic iron core that is surrounded by a gold layer and is functionalized with monoclonal anti-EGFR antibody (C225) or control rabbit IgG antibody (IgG). The nanoparticles were tested against a panel of human lung cancer cells that were mutant (HCC827, H1819), wild-type (H1299) or null (H520) for EGFR and compared to EGFR-positive normal fibroblasts (MRC9, WI38) and normal human bronchial epithelial (NHBE) cells. Treatment of tumor cells with C225-NP resulted in a strong and significant inhibitory effect of cell growth compared to normal cells. C225-NP-mediated inhibitory effect was observed only in EGFR-positive tumor cells (HCC827, H1819, H1299) but not in EGFR-null H520 cells. EGFR-mutant cells (HCC827) were the most sensitive to C225-NP. No significant growth inhibitory effects were observed in IgG-NP-treated cells when compared to untreated cells. Molecular analysis showed C225-NP selectively inhibited phosphorylated p-EGFR protein expression and EGFR-mediated signal transduction resulting in induction of autophagy followed by apoptosis. Autophagy occurred as early as twenty-four hours after treatment with an increase in LC3-II content and autophagic vacuoles observed by Western blotting and electron microscopy respectively. Apoptosis as determined by flow cytometry and Western blotting showed an increase in the number of sub-G1 population cells and cleavage of caspase-3 and PARP in C225-NP-treated cells. Optical images determined by dark-field microscopy showed an increase in the concentration of C225-NP bound to EGFR-expressing NSCLC cells but not EGFR-null NSCLC cells. C225-NP exhibited 2-7 fold higher efficiency in induction of cell killing in comparison with the same amount of free C225 antibody. Free C225 antibody did not induce autophagy in cells. Investigation into how C225-NP but not C225 antibody or NP-alone triggers autophagy and initiates apoptosis showed induction of a DNA damage response as evidenced by the formation of γH2AX foci in C225-NP-treated cells. Minimal to no γH2AX foci were observed in cells that were untreated, treated with C225 antibody or NP-alone or treated with IgG-NP. Our data show that EGFR specific NP selectively induced cytotoxic effects in EGFR-expressing lung cancer cells via a novel cell-death mechanism that is not characteristic of the free antibody thus increasing efficacy of therapy.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 3505.
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Baek SH, Jang HW, Folkman CM, Li YL, Winchester B, Zhang JX, He Q, Chu YH, Nelson CT, Rzchowski MS, Pan XQ, Ramesh R, Chen LQ, Eom CB. Ferroelastic switching for nanoscale non-volatile magnetoelectric devices. NATURE MATERIALS 2010; 9:309-314. [PMID: 20190772 DOI: 10.1038/nmat2703] [Citation(s) in RCA: 150] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Accepted: 01/25/2010] [Indexed: 05/28/2023]
Abstract
Multiferroics, where (anti-) ferromagnetic, ferroelectric and ferroelastic order parameters coexist, enable manipulation of magnetic ordering by an electric field through switching of the electric polarization. It has been shown that realization of magnetoelectric coupling in a single-phase multiferroic such as BiFeO(3) requires ferroelastic (71 degrees, 109 degrees) rather than ferroelectric (180 degrees) domain switching. However, the control of such ferroelastic switching in a single-phase system has been a significant challenge as elastic interactions tend to destabilize small switched volumes, resulting in subsequent ferroelastic back-switching at zero electric field, and thus the disappearance of non-volatile information storage. Guided by our phase-field simulations, here we report an approach to stabilize ferroelastic switching by eliminating the stress-induced instability responsible for back-switching using isolated monodomain BiFeO(3) islands. This work demonstrates a critical step to control and use non-volatile magnetoelectric coupling at the nanoscale. Beyond magnetoelectric coupling, it provides a framework for exploring a route to control multiple order parameters coupled to ferroelastic order in other low-symmetry materials.
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Ulaganatha Raja M, Gowri N, Ramesh R. Synthesis, crystal structure and catalytic activity of ruthenium(II) carbonyl complexes containing ONO and ONS donor ligands. Polyhedron 2010. [DOI: 10.1016/j.poly.2009.12.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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242
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Raja N, Ramesh R. Mononuclear ruthenium(III) complexes containing chelating thiosemicarbazones: synthesis, characterization and catalytic property. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2010; 75:713-718. [PMID: 20044307 DOI: 10.1016/j.saa.2009.11.044] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2009] [Revised: 11/17/2009] [Accepted: 11/18/2009] [Indexed: 05/28/2023]
Abstract
Mononuclear ruthenium(III) complexes of the type [RuX(EPh(3))(2)(L)] (E=P or As; X=Cl or Br; L=dibasic terdentate dehydroacetic acid thiosemicarbazones) have been synthesized from the reaction of thiosemicarbazone ligands with ruthenium(III) precursors, [RuX(3)(EPh(3))(3)] (where E=P, X=Cl; E=As, X=Cl or Br) and [RuBr(3)(PPh(3))(2)(CH(3)OH)] in benzene. The compositions of the complexes have been established by elemental analysis, magnetic susceptibility measurement, FT-IR, UV-vis and EPR spectral data. These complexes are paramagnetic and show intense d-d and charge transfer transitions in dichloromethane. The complexes show rhombic EPR spectra at LNT which are typical of low-spin distorted octahedral ruthenium(III) species. All the complexes are redox active and display an irreversible metal centered redox processes. Complex [RuCl(PPh(3))(2)(DHA-PTSC)] (5) was used as catalyst for transfer hydrogenation of ketones in the presence of isopropanol/KOH and was found to be the active species.
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Yang SY, Seidel J, Byrnes SJ, Shafer P, Yang CH, Rossell MD, Yu P, Chu YH, Scott JF, Ager JW, Martin LW, Ramesh R. Above-bandgap voltages from ferroelectric photovoltaic devices. NATURE NANOTECHNOLOGY 2010; 5:143-7. [PMID: 20062051 DOI: 10.1038/nnano.2009.451] [Citation(s) in RCA: 441] [Impact Index Per Article: 31.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2009] [Accepted: 11/16/2009] [Indexed: 05/25/2023]
Abstract
In conventional solid-state photovoltaics, electron-hole pairs are created by light absorption in a semiconductor and separated by the electric field spaning a micrometre-thick depletion region. The maximum voltage these devices can produce is equal to the semiconductor electronic bandgap. Here, we report the discovery of a fundamentally different mechanism for photovoltaic charge separation, which operates over a distance of 1-2 nm and produces voltages that are significantly higher than the bandgap. The separation happens at previously unobserved nanoscale steps of the electrostatic potential that naturally occur at ferroelectric domain walls in the complex oxide BiFeO(3). Electric-field control over domain structure allows the photovoltaic effect to be reversed in polarity or turned off. This new degree of control, and the high voltages produced, may find application in optoelectronic devices.
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Zeches RJ, Rossell MD, Zhang JX, Hatt AJ, He Q, Yang CH, Kumar A, Wang CH, Melville A, Adamo C, Sheng G, Chu YH, Ihlefeld JF, Erni R, Ederer C, Gopalan V, Chen LQ, Schlom DG, Spaldin NA, Martin LW, Ramesh R. A strain-driven morphotropic phase boundary in BiFeO3. Science 2010; 326:977-80. [PMID: 19965507 DOI: 10.1126/science.1177046] [Citation(s) in RCA: 320] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Piezoelectric materials, which convert mechanical to electrical energy and vice versa, are typically characterized by the intimate coexistence of two phases across a morphotropic phase boundary. Electrically switching one to the other yields large electromechanical coupling coefficients. Driven by global environmental concerns, there is currently a strong push to discover practical lead-free piezoelectrics for device engineering. Using a combination of epitaxial growth techniques in conjunction with theoretical approaches, we show the formation of a morphotropic phase boundary through epitaxial constraint in lead-free piezoelectric bismuth ferrite (BiFeO3) films. Electric field-dependent studies show that a tetragonal-like phase can be reversibly converted into a rhombohedral-like phase, accompanied by measurable displacements of the surface, making this new lead-free system of interest for probe-based data storage and actuator applications.
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Ramesh R, Ioannides CG, Roth JA, Chada S. Adenovirus-mediated interleukin (IL)-24 immunotherapy for cancer. Methods Mol Biol 2010; 651:241-70. [PMID: 20686970 DOI: 10.1007/978-1-60761-786-0_14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Interleukin-24 (IL-24) is a member of the IL-10 cytokine family. IL-24, also known as melanoma differentiation associated gene 7 (mda-7), is a unique cytokine in that it has cytokine properties and functions as a novel tumor suppressor gene. Studies by us and other investigators using viral and non-viral vectors have demonstrated IL-24 overexpression in human cancer cells inhibited tumor growth both in vitro and in vivo. A majority of these studies using immunodeficient animal models have focused on demonstrating the direct anticancer properties of IL-24. Very few studies have focused on studying the immunotherapeutic properties of IL-24 despite it being reported to function as a Th1 cytokine. A phase I clinical trial using an adenovirus vector expressing IL-24 (Ad-IL24/INGN241) reported Ad-IL24 treatment of cancer patients resulted in changes in cytokines and T cells. However, well-designed and detailed preclinical studies to support the clinical findings are warranted. Demonstrating immune modulation by IL-24 will provide a rationale for developing IL-24-based immunotherapeutic approaches for cancer treatment.In the present chapter, we provide experimental details for conducting IL-24-based immunotherapy studies. As it is not possible for the authors to cover all of the information the authors recommend reading other immunology-based literature and procedures for a better understanding of conducting preclinical studies.
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Chidambara S, John Peter A, Prasanna M, Karmegam U, Balaji K, Ramesh R, Paramaguru P, Pethaperua S. A Study on the Impact of Landuse Pattern in the Groundwater Quality in and Around Madurai Region, South India-Using GIS Techniques. ACTA ACUST UNITED AC 2010. [DOI: 10.3923/ojesci.2010.27.31] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Balke N, Choudhury S, Jesse S, Huijben M, Chu YH, Baddorf AP, Chen LQ, Ramesh R, Kalinin SV. Deterministic control of ferroelastic switching in multiferroic materials. NATURE NANOTECHNOLOGY 2009; 4:868-75. [PMID: 19893529 DOI: 10.1038/nnano.2009.293] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2009] [Accepted: 09/03/2009] [Indexed: 05/22/2023]
Abstract
Multiferroic materials showing coupled electric, magnetic and elastic orderings provide a platform to explore complexity and new paradigms for memory and logic devices. Until now, the deterministic control of non-ferroelectric order parameters in multiferroics has been elusive. Here, we demonstrate deterministic ferroelastic switching in rhombohedral BiFeO(3) by domain nucleation with a scanning probe. We are able to select among final states that have the same electrostatic energy, but differ dramatically in elastic or magnetic order, by applying voltage to the probe while it is in lateral motion. We also demonstrate the controlled creation of a ferrotoroidal order parameter. The ability to control local elastic, magnetic and torroidal order parameters with an electric field will make it possible to probe local strain and magnetic ordering, and engineer various magnetoelectric, domain-wall-based and strain-coupled devices.
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Ramesh R, De Silva B, Atherton DJ. Congenital tufted angioma with persistent low-grade coagulopathy. Clin Exp Dermatol 2009; 34:e766-8. [DOI: 10.1111/j.1365-2230.2009.03488.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Sundaram S, Trivedi R, Durairaj C, Ramesh R, Ambati BK, Kompella UB. Targeted drug and gene delivery systems for lung cancer therapy. Clin Cancer Res 2009; 15:7299-308. [PMID: 19920099 DOI: 10.1158/1078-0432.ccr-09-1745] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
PURPOSE To evaluate the efficacy of a novel docetaxel derivative of deslorelin, a luteinizing hormone-releasing hormone (LHRH) agonist, and its combination in vivo with RGD peptide conjugated nanoparticles encapsulating an antiangiogenic, anti-vascular endothelial growth factor (VEGF) intraceptor (Flt23k; RGD-Flt23k-NP) in H1299 lung cancer cells and/or xenografts in athymic nude BALB/c mice. EXPERIMENTAL DESIGN The in vitro and in vivo efficacy of the deslorelin-docetaxel conjugate was evaluated in H1299 cells and xenografts in athymic nude mice. Coadministration of deslorelin-docetaxel conjugate and RGD-Flt23k-NP was tested in vivo in mice. Tumor inhibition, apoptosis, and VEGF inhibition were estimated in each of the treatment groups. RESULTS The conjugate enhanced in vitro docetaxel efficacy by 13-fold in H1299 cells compared with docetaxel at 24 hours, and this effect was inhibited following reduction of LHRH receptor expression by an antisense oligonucleotide. Combination of the conjugate with the RGD-Flt23k-NP in vivo resulted in an 82- and 15-fold tumor growth inhibition on day 39 following repeated weekly i.v. injections and a single intratumoral (i.t.) injection, respectively. These effects were significantly greater than individual targeted therapies or docetaxel alone. Similarly, apoptotic indices for the combination therapy were 14% and 10% in the i.v. and i.t. groups, respectively, and higher than the individual therapies. Combination therapy groups exhibited greater VEGF inhibition in both the i.v. and i.t. groups. CONCLUSIONS Docetaxel efficacy was enhanced by LHRH receptor-targeted deslorelin conjugate and further improved by combination with targeted antiangiogenic nanoparticle gene therapy. Combination of novel targeted therapeutic approaches described here provides an attractive alternative to the current treatment options for lung cancer therapy.
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de Silva R, Karunaratne K, Mendis LN, Ramesh R, Chow VTK. PCR detection and typing of human papilloma virus DNA in squamous carcinoma of the cervix in a cohort of Sri Lankan women. CEYLON MEDICAL JOURNAL 2009; 51:114-7. [PMID: 17315590 DOI: 10.4038/cmj.v51i3.1255] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
OBJECTIVE To determine the prevalence of human papilloma virus (HPV) types 16 and 18 in squamous carcinomas of the cervix in Sri Lanka. DESIGN Case control study. SETTING One gynaecological unit at the Cancer Institute, Maharagama, Sri Lanka. PATIENTS 15 patients with squamous carcinoma of the cervix, and 15 age matched controls with histologically normal cervices. MEASUREMENTS DNA was extracted from paraffin embedded cervical biopsies. Polymerase chain reaction was performed on extracted DNA employing primers specific for HPV types 16 and 18. RESULTS HPV 16 DNA was detected in 11 out of 15 cervical cancer biopsies (73.3%), in comparison with 3 out of 15 normal controls (20%). HPV 18 was detected in 3 out of 15 cervical cancer biopsies, but not in a single control biopsy. CONCLUSION Despite the limited number of cases in this cohort, this study supports the strong association between HPV 16 and squamous cancer of the cervix.
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