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Fang H, Mahalingam H, Li X, Han X, Qiu Z, Han Y, Noori K, Dulal D, Chen H, Lyu P, Yang T, Li J, Su C, Chen W, Cai Y, Neto AHC, Novoselov KS, Rodin A, Lu J. Atomically precise vacancy-assembled quantum antidots. Nat Nanotechnol 2023; 18:1401-1408. [PMID: 37653051 DOI: 10.1038/s41565-023-01495-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 08/01/2023] [Indexed: 09/02/2023]
Abstract
Patterning antidots, which are regions of potential hills that repel electrons, into well-defined antidot lattices creates fascinating artificial periodic structures, leading to anomalous transport properties and exotic quantum phenomena in two-dimensional systems. Although nanolithography has brought conventional antidots from the semiclassical regime to the quantum regime, achieving precise control over the size of each antidot and its spatial period at the atomic scale has remained challenging. However, attaining such control opens the door to a new paradigm, enabling the creation of quantum antidots with discrete quantum hole states, which, in turn, offer a fertile platform to explore novel quantum phenomena and hot electron dynamics in previously inaccessible regimes. Here we report an atomically precise bottom-up fabrication of a series of atomic-scale quantum antidots through a thermal-induced assembly of a chalcogenide single vacancy in PtTe2. Such quantum antidots consist of highly ordered single-vacancy lattices, spaced by a single Te atom, reaching the ultimate downscaling limit of antidot lattices. Increasing the number of single vacancies in quantum antidots strengthens the cumulative repulsive potential and consequently enhances the collective interference of multiple-pocket scattered quasiparticles inside quantum antidots, creating multilevel quantum hole states with a tunable gap from the telecom to far-infrared regime. Moreover, precisely engineered quantum hole states of quantum antidots are geometry protected and thus survive on oxygen substitutional doping. Therefore, single-vacancy-assembled quantum antidots exhibit unprecedented robustness and property tunability, positioning them as highly promising candidates for advancing quantum information and photocatalysis technologies.
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Affiliation(s)
- Hanyan Fang
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Harshitra Mahalingam
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
| | - Xinzhe Li
- School of Energy and Power Engineering, Xi'an Jiaotong University, Xi'an, China
| | - Xu Han
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Zhizhan Qiu
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
| | - Yixuan Han
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Keian Noori
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore, Singapore
| | | | - Hongfei Chen
- Joint Key Laboratory of Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, China
| | - Pin Lyu
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Tianhao Yang
- Department of Chemistry, National University of Singapore, Singapore, Singapore
| | - Jing Li
- Key Laboratory of Bio-inspired Smart Interfacial Science and Technology of Ministry of Education, School of Chemistry, Beihang University, Beijing, China
| | - Chenliang Su
- International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen, China
| | - Wei Chen
- Department of Chemistry, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore, Singapore
| | - Yongqing Cai
- Joint Key Laboratory of Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, China
| | - A H Castro Neto
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore, Singapore
| | - Kostya S Novoselov
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore, Singapore
| | - Aleksandr Rodin
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore, Singapore.
- Yale-NUS College, Singapore, Singapore.
- Materials Science and Engineering, National University of Singapore, Singapore, Singapore.
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, Singapore, Singapore.
- Institute for Functional Intelligent Materials, National University of Singapore, Singapore, Singapore.
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore, Singapore.
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Biswas H, Mahalingam H, Rodin A. Numerical package for QFT calculations of defect-induced phenomena in graphene. J Phys Condens Matter 2022; 51:025902. [PMID: 36327462 DOI: 10.1088/1361-648x/aca002] [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: 09/14/2022] [Accepted: 11/03/2022] [Indexed: 06/16/2023]
Abstract
We introduce a computationally efficient method based on the path integral formalism to describe defect-modified graphene. By taking into account the entire Brillouin zone, our approach respects the lattice symmetry and can be used to investigate both short-range and long-range effects. The proposed method's key advantage is that the computational complexity does not increase with the system size, scaling, instead, with the number of defects. Our aim is to make the quantum-field calculations in graphene accessible to the experimental community. We demonstrate our method's capabilities by exploring the well-known graphene-mediated Ruderman-Kittel-Kasuya-Yoshida interaction and by performing a detailed study of the atomic collapse in the presence of defects.
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Affiliation(s)
- Hillol Biswas
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, 117546, Singapore
| | - Harshitra Mahalingam
- Institute for Functional Intelligent Materials, National University of Singapore, 4 Science Drive 2, 117544, Singapore
| | - Aleksandr Rodin
- Centre for Advanced 2D Materials, National University of Singapore, 6 Science Drive 2, 117546, Singapore
- Yale-NUS College, 16 College Avenue West, 138527, Singapore
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Telychko M, Noori K, Biswas H, Dulal D, Chen Z, Lyu P, Li J, Tsai HZ, Fang H, Qiu Z, Yap ZW, Watanabe K, Taniguchi T, Wu J, Loh KP, Crommie MF, Rodin A, Lu J. Gate-Tunable Resonance State and Screening Effects for Proton-Like Atomic Charge in Graphene. Nano Lett 2022; 22:8422-8429. [PMID: 36214509 DOI: 10.1021/acs.nanolett.2c02235] [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] [Indexed: 06/16/2023]
Abstract
The ability to create a robust and well-defined artificial atomic charge in graphene and understand its carrier-dependent electronic properties represents an important goal toward the development of graphene-based quantum devices. Herein, we devise a new pathway toward the atomically precise embodiment of point charges into a graphene lattice by posterior (N) ion implantation into a back-gated graphene device. The N dopant behaves as an in-plane proton-like charge manifested by formation of the characteristic resonance state in the conduction band. Scanning tunneling spectroscopy measurements at varied charge carrier densities reveal a giant energetic renormalization of the resonance state up to 220 meV with respect to the Dirac point, accompanied by the observation of gate-tunable long-range screening effects close to individual N dopants. Joint density functional theory and tight-binding calculations with modified perturbation potential corroborate experimental findings and highlight the short-range character of N-induced perturbation.
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Affiliation(s)
- Mykola Telychko
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Keian Noori
- Institute for Functional Intelligent Materials, National University of Singapore, 117544, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
| | - Hillol Biswas
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
- Department of Physics, National University of Singapore, 2 Science Drive 3, 117542, Singapore
| | - Dikshant Dulal
- Yale-NUS College, 16 College Avenue West, 138527, Singapore
| | - Zhaolong Chen
- Institute for Functional Intelligent Materials, National University of Singapore, 117544, Singapore
| | - Pin Lyu
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Jing Li
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
| | - Hsin-Zon Tsai
- Department of Physics, University of California, Berkeley94720, California, United States
| | - Hanyan Fang
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Zhizhan Qiu
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Zhun Wai Yap
- Yale-NUS College, 16 College Avenue West, 138527, Singapore
| | - Kenji Watanabe
- Research Center for Functional Materials, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Takashi Taniguchi
- International Center for Materials Nanoarchitectonics, National Institute for Materials Science, 1-1 Namiki, Tsukuba305-0044, Japan
| | - Jing Wu
- Institute of Materials Research and Engineering, Agency for Science, Technology and Research, 08-03, 2 Fusionopolis Way, Singapore138634, Singapore
| | - Kian Ping Loh
- Department of Chemistry, National University of Singapore, 117543, Singapore
| | - Michael F Crommie
- Department of Physics, University of California, Berkeley94720, California, United States
| | - Aleksandr Rodin
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
- Yale-NUS College, 16 College Avenue West, 138527, Singapore
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, 117543, Singapore
- Institute for Functional Intelligent Materials, National University of Singapore, 117544, Singapore
- Centre for Advanced 2D Materials, National University of Singapore, 117543, Singapore
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Fang H, Gallardo A, Dulal D, Qiu Z, Su J, Telychko M, Mahalingam H, Lyu P, Han Y, Zheng Y, Cai Y, Rodin A, Jelínek P, Lu J. Electronic Self-Passivation of Single Vacancy in Black Phosphorus via Ionization. Phys Rev Lett 2022; 128:176801. [PMID: 35570438 DOI: 10.1103/physrevlett.128.176801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Revised: 02/28/2022] [Accepted: 03/11/2022] [Indexed: 06/15/2023]
Abstract
We report that monoelemental black phosphorus presents a new electronic self-passivation scheme of single vacancy (SV). By means of low-temperature scanning tunneling microscopy and noncontact atomic force microscopy, we demonstrate that the local reconstruction and ionization of SV into negatively charged SV^{-} leads to the passivation of dangling bonds and, thus, the quenching of in-gap states, which can be achieved by mild thermal annealing or STM tip manipulation. SV exhibits a strong and symmetric Friedel oscillation (FO) pattern, while SV^{-} shows an asymmetric FO pattern with local perturbation amplitude reduced by one order of magnitude and a faster decay rate. The enhanced passivation by forming SV^{-} can be attributed to its weak dipolelike perturbation, consistent with density-functional theory numerical calculations. Therefore, self-passivated SV^{-} is electrically benign and acts as a much weaker scattering center, which may hold the key to further enhance the charge mobility of black phosphorus and its analogs.
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Affiliation(s)
- Hanyan Fang
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Aurelio Gallardo
- Institute of Physics, Academy of Sciences of the Czech Republic, Prague 162 00, Czech Republic
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, Prague 180 00, Czech Republic
| | - Dikshant Dulal
- Yale-NUS College, 16 College Avenue West, Singapore 138527, Singapore
| | - Zhizhan Qiu
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Jie Su
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Mykola Telychko
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | | | - Pin Lyu
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Yixuan Han
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
| | - Yi Zheng
- Zhejiang Province Key Laboratory of Quantum Technology and Device, Department of Physics, Zhejiang University, Hangzhou 312007, China
| | - Yongqing Cai
- Joint Key Laboratory of Ministry of Education, Institute of Applied Physics and Materials Engineering, University of Macau, Taipa, Macau 999078, China
| | - Aleksandr Rodin
- Yale-NUS College, 16 College Avenue West, Singapore 138527, Singapore
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore 117543, Singapore
| | - Pavel Jelínek
- Institute of Physics, Academy of Sciences of the Czech Republic, Prague 162 00, Czech Republic
- Regional Centre of Advanced Technologies and Materials, Czech Advanced Technology and Research Institute (CATRIN), Palacký University Olomouc, Olomouc 78371, Czech Republic
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, Singapore 117543, Singapore
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore 117543, Singapore
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Peng X, Mahalingam H, Dong S, Mutombo P, Su J, Telychko M, Song S, Lyu P, Ng PW, Wu J, Jelínek P, Chi C, Rodin A, Lu J. Visualizing designer quantum states in stable macrocycle quantum corrals. Nat Commun 2021; 12:5895. [PMID: 34625542 PMCID: PMC8501084 DOI: 10.1038/s41467-021-26198-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 09/20/2021] [Indexed: 02/08/2023] Open
Abstract
Creating atomically precise quantum architectures with high digital fidelity and desired quantum states is an important goal in a new era of quantum technology. The strategy of creating these quantum nanostructures mainly relies on atom-by-atom, molecule-by-molecule manipulation or molecular assembly through non-covalent interactions, which thus lack sufficient chemical robustness required for on-chip quantum device operation at elevated temperature. Here, we report a bottom-up synthesis of covalently linked organic quantum corrals (OQCs) with atomic precision to induce the formation of topology-controlled quantum resonance states, arising from a collective interference of scattered electron waves inside the quantum nanocavities. Individual OQCs host a series of atomic orbital-like resonance states whose orbital hybridization into artificial homo-diatomic and hetero-diatomic molecular-like resonance states can be constructed in Cassini oval-shaped OQCs with desired topologies corroborated by joint ab initio and analytic calculations. Our studies open up a new avenue to fabricate covalently linked large-sized OQCs with atomic precision to engineer desired quantum states with high chemical robustness and digital fidelity for future practical applications.
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Affiliation(s)
- Xinnan Peng
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | | | - Shaoqiang Dong
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Pingo Mutombo
- Institute of Physics, Czech Academy of Sciences, Prague, 16200, Czech Republic
| | - Jie Su
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Mykola Telychko
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Shaotang Song
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Pin Lyu
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Pei Wen Ng
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Jishan Wu
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore
| | - Pavel Jelínek
- Institute of Physics, Czech Academy of Sciences, Prague, 16200, Czech Republic.
- Regional Centre of Advanced Technologies and Materials, Palacký University, Olomouc, 78371, Czech Republic.
| | - Chunyan Chi
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore.
| | - Aleksandr Rodin
- Yale-NUS College, 16 College Avenue West, Singapore, 138527, Singapore.
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore, 117543, Singapore.
| | - Jiong Lu
- Department of Chemistry, National University of Singapore, Singapore, 117543, Singapore.
- Centre for Advanced 2D Materials (CA2DM), National University of Singapore, Singapore, 117543, Singapore.
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Lin S, Carvalho A, Yan S, Li R, Kim S, Rodin A, Carvalho L, Chan EM, Wang X, Castro Neto AH, Yao J. Accessing valley degree of freedom in bulk Tin(II) sulfide at room temperature. Nat Commun 2018; 9:1455. [PMID: 29654301 PMCID: PMC5899090 DOI: 10.1038/s41467-018-03897-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [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: 01/08/2018] [Accepted: 03/21/2018] [Indexed: 11/09/2022] Open
Abstract
The field of valleytronics has promised greater control of electronic and spintronic systems with an additional valley degree of freedom. However, conventional and two-dimensional valleytronic systems pose practical challenges in the utilization of this valley degree of freedom. Here we show experimental evidences of the valley effect in a bulk, ambient, and bias-free model system of Tin(II) sulfide. We elucidate the direct access and identification of different sets of valleys, based primarily on the selectivity in absorption and emission of linearly polarized light by optical reflection/transmission and photoluminescence measurements, and demonstrate strong optical dichroic anisotropy of up to 600% and nominal polarization degrees of up to 96% for the two valleys with band-gap values 1.28 and 1.48 eV, respectively; the ease of valley selection further manifested in their non-degenerate nature. Such discovery enables a new platform for better access and control of valley polarization. Valleytronics leverages the valley degree of freedom to engineer light-matter interaction. Here, the authors demonstrate a room temperature, bias-free valley effect in bulk SnS by means of spectroscopic measurements, previously unattainable using atomically thin transition metal dichalcogenides.
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Affiliation(s)
- Shuren Lin
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA.,The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Alexandra Carvalho
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Shancheng Yan
- School of Geography and Biological Information, Nanjing University of Posts and Telecommunications, 210023, Nanjing, People's Republic of China
| | - Roger Li
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Sujung Kim
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Aleksandr Rodin
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Lídia Carvalho
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Emory M Chan
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Xi Wang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Antonio H Castro Neto
- Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore, 117546, Singapore
| | - Jie Yao
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA. .,Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.
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Rodin A, Soomere T, Parnell KE, Zaggia L. Numerical simulation of the propagation of ship-induced Riemann waves of depression into the Venice Lagoon. Proc Estonian Acad Sci 2015. [DOI: 10.3176/proc.2015.1.04] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Torsvik T, Herrmann H, Didenkulova I, Rodin A. Analysis of ship wake transformation in the coastal zone using time–frequency methods. Proc Estonian Acad Sci 2015. [DOI: 10.3176/proc.2015.3s.08] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Antonov A, Gaidarov M, Ivanov M, Kadrev D, Aïche M, Barreau G, Czajkowski S, Jurado B, Belier G, Chatillon A, Granier T, Taieb J, Doré D, Letourneau A, Ridikas D, Dupont E, Berthoumieux E, Panebianco S, Farget F, Schmitt C, Audouin L, Khan E, Tassan-Got L, Aumann T, Beller P, Boretzky K, Dolinskii A, Egelhof P, Emling H, Franzke B, Geissel H, Kelic-Heil A, Kester O, Kurz N, Litvinov Y, Münzenberg G, Nolden F, Schmidt KH, Scheidenberger C, Simon H, Steck M, Weick H, Enders J, Pietralla N, Richter A, Schrieder G, Zilges A, Distler M, Merkel H, Müller U, Junghans A, Lenske H, Fujiwara M, Suda T, Kato S, Adachi T, Hamieh S, Harakeh M, Kalantar-Nayestanaki N, Wörtche H, Berg G, Koop I, Logatchov P, Otboev A, Parkhomchuk V, Shatilov D, Shatunov P, Shatunov Y, Shiyankov S, Shvartz D, Skrinsky A, Chulkov L, Danilin B, Korsheninnikov A, Kuzmin E, Ogloblin A, Volkov V, Grishkin Y, Lisin V, Mushkarenkov A, Nedorezov V, Polonski A, Rudnev N, Turinge A, Artukh A, Avdeichikov V, Ershov S, Fomichev A, Golovkov M, Gorshkov A, Grigorenko L, Klygin S, Krupko S, Meshkov I, Rodin A, Sereda Y, Seleznev I, Sidorchuk S, Syresin E, Stepantsov S, Ter-Akopian G, Teterev Y, Vorontsov A, Kamerdzhiev S, Litvinova E, Karataglidis S, Alvarez Rodriguez R, Borge M, Fernandez Ramirez C, Garrido E, Sarriguren P, Vignote J, Fraile Prieto L, Lopez Herraiz J, Moya de Guerra E, Udias-Moinelo J, Amaro Soriano J, Lallena Rojo A, Caballero J, Johansson H, Jonson B, Nilsson T, Nyman G, Zhukov M, Golubev P, Rudolph D, Hencken K, Jourdan J, Krusche B, Rauscher T, Kiselev D, Trautmann D, Al-Khalili J, Catford W, Johnson R, Stevenson P, Barton C, Jenkins D, Lemmon R, Chartier M, Cullen D, Bertulani C, Heinz A. The electron–ion scattering experiment ELISe at the International Facility for Antiproton and Ion Research (FAIR)—A conceptual design study. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 2011. [DOI: 10.1016/j.nima.2010.12.246] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Rodin A, Mashiter G, Quartern R, Pistofidis G, Fogelman I, Maisey MN, Chapman MG, Clarke S. Thyroid function in normal pregnancy. J OBSTET GYNAECOL 2009. [DOI: 10.3109/01443618909151118] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Bertaux JL, Vandaele AC, Korablev O, Villard E, Fedorova A, Fussen D, Quémerais E, Belyaev D, Mahieux A, Montmessin F, Muller C, Neefs E, Nevejans D, Wilquet V, Dubois JP, Hauchecorne A, Stepanov A, Vinogradov I, Rodin A, Bertaux JL, Nevejans D, Korablev O, Montmessin F, Vandaele AC, Fedorova A, Cabane M, Chassefière E, Chaufray JY, Dimarellis E, Dubois JP, Hauchecorne A, Leblanc F, Lefèvre F, Rannou P, Quémerais E, Villard E, Fussen D, Muller C, Neefs E, Van Ransbeeck E, Wilquet V, Rodin A, Stepanov A, Vinogradov I, Zasova L, Forget F, Lebonnois S, Titov D, Rafkin S, Durry G, Gérard JC, Sandel B. A warm layer in Venus' cryosphere and high-altitude measurements of HF, HCl, H2O and HDO. Nature 2008; 450:646-9. [PMID: 18046397 DOI: 10.1038/nature05974] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2007] [Accepted: 05/22/2007] [Indexed: 11/09/2022]
Abstract
Venus has thick clouds of H2SO4 aerosol particles extending from altitudes of 40 to 60 km. The 60-100 km region (the mesosphere) is a transition region between the 4 day retrograde superrotation at the top of the thick clouds and the solar-antisolar circulation in the thermosphere (above 100 km), which has upwelling over the subsolar point and transport to the nightside. The mesosphere has a light haze of variable optical thickness, with CO, SO2, HCl, HF, H2O and HDO as the most important minor gaseous constituents, but the vertical distribution of the haze and molecules is poorly known because previous descent probes began their measurements at or below 60 km. Here we report the detection of an extensive layer of warm air at altitudes 90-120 km on the night side that we interpret as the result of adiabatic heating during air subsidence. Such a strong temperature inversion was not expected, because the night side of Venus was otherwise so cold that it was named the 'cryosphere' above 100 km. We also measured the mesospheric distributions of HF, HCl, H2O and HDO. HCl is less abundant than reported 40 years ago. HDO/H2O is enhanced by a factor of approximately 2.5 with respect to the lower atmosphere, and there is a general depletion of H2O around 80-90 km for which we have no explanation.
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Affiliation(s)
- Jean-Loup Bertaux
- Service d'Aéronomie du CNRS/IPSL, Verrières-le-Buisson 91371, France.
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Korablev O, Bertaux JL, Fedorova A, Fonteyn D, Stepanov A, Kalinnikov Y, Kiselev A, Grigoriev A, Jegoulev V, Perrier S, Dimarellis E, Dubois JP, Reberac A, Van Ransbeeck E, Gondet B, Montmessin F, Rodin A. SPICAM IR acousto-optic spectrometer experiment on Mars Express. ACTA ACUST UNITED AC 2006. [DOI: 10.1029/2006je002696] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Abstract
The minimum sum of branch lengths (S), or the minimum evolution (ME) principle, has been shown to be a good optimization criterion in phylogenetic inference. Unfortunately, the number of topologies to be analyzed is computationally prohibitive when a large number of taxa are involved. Therefore, simplified, heuristic methods, such as the neighbor-joining (NJ) method, are usually employed instead. The NJ method analyzes only a small number of trees (compared with the size of the entire search space); so, the tree obtained may not be the ME tree (for which the S value is minimum over the entire search space). Different compromises between very restrictive and exhaustive search spaces have been proposed recently. In particular, the "stepwise algorithm" (SA) utilizes what is known in computer science as the "beam search," whereas the NJ method employs a "greedy search." SA is virtually guaranteed to find the ME trees while being much faster than exhaustive search algorithms. In this study we propose an even faster method for finding the ME tree. The new algorithm adjusts its search exhaustiveness (from greedy to complete) according to the statistical reliability of the tree node being reconstructed. It is also virtually guaranteed to find the ME tree. The performances and computational efficiencies of ME, SA, NJ, and our new method were compared in extensive simulation studies. The new algorithm was found to perform practically as well as the SA (and, therefore, ME) methods and slightly better than the NJ method. For searching for the globally optimal ME tree, the new algorithm is significantly faster than existing ones, thus making it relatively practical for obtaining all trees with an S value equal to or smaller than that of the NJ tree, even when a large number of taxa is involved.
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Affiliation(s)
- A Rodin
- Human Genetics Center, School of Public Health, University of Texas Health Science Center, Texas, Houston 77225, USA
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Walker BR, Rodin A, Taylor NF, Clayton RN. Endogenous inhibitors of 11beta-hydroxysteroid dehydrogenase type 1 do not explain abnormal cortisol metabolism in polycystic ovary syndrome. Clin Endocrinol (Oxf) 2000; 52:77-80. [PMID: 10651756 DOI: 10.1046/j.1365-2265.2000.00893.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE The aetiology of enhanced adrenal androgen secretion in polycystic ovary syndrome is poorly understood. Previous reports suggest that enhanced peripheral metabolism of cortisol results in decreased negative feedback suppression of ACTH secretion, either by enhanced inactivation of cortisol by 5alpha-reductase or impaired reactivation of cortisol by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). Endogenous inhibitors of hepatic 11beta-HSD1 can be extracted from urine. We have tested the hypothesis that these are increased in patients with polycystic ovary syndrome. DESIGN A case-control study. PATIENTS 57 patients with polycystic ovary syndrome and 27 healthy control women. MEASUREMENTS Aliquots from 24 h urine samples were extracted with Sep-Paks and incubated with rat liver microsomes in which 11beta-HSD1 activity was quantified by conversion of 3H-corticosterone to 3H-11-dehydrocorticosterone. RESULTS Inhibition of 11beta-HSD1 activity was not different in extracts from patients compared with controls (40.8 +/- 18.9 arbitrary units in patients vs. 42.7 +/- 16.6 in controls, mean (+/- SEM, P > 0.60) and did not correlate with ratios of cortisol metabolites in urine or with body mass index. CONCLUSIONS The altered cortisol metabolism in polycystic ovarian syndrome, which is consistent with impaired 11beta-HSD1 activity, cannot be accounted for by increased production of measurable endogenous inhibitors of this enzyme.
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Affiliation(s)
- B R Walker
- University of Edinburgh, Endocrinology Unit, Western General Hospital, Edinburgh, UK.
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16
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Sun H, Rodin A, Zhou Y, Dickinson DP, Harper DE, Hewett-Emmett D, Li WH. Evolution of paired domains: isolation and sequencing of jellyfish and hydra Pax genes related to Pax-5 and Pax-6. Proc Natl Acad Sci U S A 1997; 94:5156-61. [PMID: 9144207 PMCID: PMC24648 DOI: 10.1073/pnas.94.10.5156] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Pax proteins are a family of transcription factors with a highly conserved paired domain; many members also contain a paired-type homeodomain and/or an octapeptide. Nine mammalian Pax genes are known and classified into four subgroups: Pax-1/9, Pax-2/5/8, Pax-3/7, and Pax-4/6. Most of these genes are involved in nervous system development. In particular, Pax-6 is a key regulator that controls eye development in vertebrates and Drosophila. Although the Pax-4/6 subgroup seems to be more closely related to Pax-2/5/8 than to Pax-3/7 or Pax-1/9, its evolutionary origin is unknown. We therefore searched for a Pax-6 homolog and related genes in Cnidaria, which is the lowest phylum of animals that possess a nervous system and eyes. A sea nettle (a jellyfish) genomic library was constructed and two pax genes (Pax-A and -B) were isolated and partially sequenced. Surprisingly, unlike most known Pax genes, the paired box in these two genes contains no intron. In addition, the complete cDNA sequences of hydra Pax-A and -B were obtained. Hydra Pax-B contains both the homeodomain and the octapeptide, whereas hydra Pax-A contains neither. DNA binding assays showed that sea nettle Pax-A and -B and hydra Pax-A paired domains bound to a Pax-5/6 site and a Pax-5 site, although hydra Pax-B paired domain bound neither. An alignment of all available paired domain sequences revealed two highly conserved regions, which cover the DNA binding contact positions. Phylogenetic analysis showed that Pax-A and especially Pax-B were more closely related to Pax-2/5/8 and Pax-4/6 than to Pax-1/9 or Pax-3/7 and that the Pax genes can be classified into two supergroups: Pax-A/Pax-B/Pax-2/5/8/4/6 and Pax-1/9/3/7. From this analysis and the gene structure, we propose that modern Pax-4/6 and Pax-2/5/8 genes evolved from an ancestral gene similar to cnidarian Pax-B, having both the homeodomain and the octapeptide.
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Affiliation(s)
- H Sun
- Human Genetics Center, School of Public Health, University of Texas, P.O. Box 20334, Houston, TX 77225, USA
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17
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Abstract
A total of 1268 available (excluding mitochondrial) tRNA sequences was used to reconstruct the common consensus image of their acceptor domains. Its structure appeared as a 11-bp-long double-stranded palindrome with complementary triplets in the center, each flanked by the 3'-ACCD and NGGU-5' motifs on each strand (D, base determinator). The palindrome readily extends up to the modern tRNA-like cloverleaf passing through an intermediate hairpin having in the center the single-stranded triplet, in supplement to its double-stranded precursor. The latter might represent an original anticodon-codon pair mapped at 1-2-3 positions of the present-day tRNA acceptors. This conclusion is supported by the striking correlation: in pairs of consensus tRNAs with complementary anticodons, their bases at the 2nd position of the acceptor stem were also complementary. Accordingly, inverse complementarity was also evident at the 71st position of the acceptor stem. With a single exception (tRNA(Phe)-tRNA(Glu) pair), the parallelism is especially impressive for the pairs of tRNAs recognized by aminoacyl-tRNA synthetases (aaRS) from the opposite classes. The above complementarity still doubly presented at the key central position of real single-stranded anticodons and their hypothetical double-stranded precursors is consistent with our previous data pointing to the double-strand use of ancient RNAs in the origin of the main actors in translation- tRNAs with complementary anticodons and the two classes of aaRS.
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Affiliation(s)
- S Rodin
- Beckman Research Institute of the City of Hope, Duarte, CA 91010, USA
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18
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Abstract
Rectal and cervicovaginal mucosa are common routes of transmission of HIV, although the mechanism of transmission is unknown. We have investigated human rectal and cervicovaginal epithelia for the expression of complement receptors (CR) and cell adhesion molecules which may be involved in HIV and other infections. In rectal mucosa, CR3 was detected in the surface and crypt epithelial cells by immunohistology, using MoAbs to CD18 and CD11b in 10 out of 15 specimens. RNA transcripts encoding both CD11b and CD18 were also demonstrated in surface and crypt epithelial cells by in situ hybridization. Although CD11b was detected in the epithelial cells in three out of the 14 cervicovaginal specimens, we were unable to detect CD18. We suggest that expression of the CD11b/CD18 heterodimer might facilitate transmission of HIV by enhancing binding of HIV-antibody complexes in seminal fluid to epithelial cells. Alternatively, since intercellular adhesion molecule-1 (ICAM-1) is a receptor for CD11b/CD18, this may promote adhesion between epithelial cells and HIV-infected mononuclear cells in seminal fluid.
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Affiliation(s)
- L A Hussain
- Department of Immunology, United Medical School, Guy's Hospital, London, UK
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Oganwu SO, Sanusi FA, Ngui CF, Rodin A, Simanowitz MD. Ischaemic bowel secondary to Meckel's diverticulum co-existing with placental abruption. J OBSTET GYNAECOL 1995. [DOI: 10.3109/01443619509020692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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20
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Abstract
BACKGROUND Hyperandrogenemia is the hallmark of the polycystic ovary syndrome, yet the relative contributions of the adrenal cortex and ovary to the overproduction of androgen remain unclear. To identify possible causes of adrenocortical overactivity, we studied the metabolism of adrenal and ovarian steroid hormones in women with this disorder. METHODS We measured 24-hour urinary excretion of steroid hormone metabolites by high-resolution capillary gas chromatography in 65 women with the polycystic ovary syndrome and 45 normal women matched for body-mass index. RESULTS After adjustment for body-mass index, the urinary excretion of testosterone and androstenedione metabolites was 1.9 times higher in the women with the syndrome than in the normal women, and the excretion of dehydroepiandosterone metabolites (C19 steroid sulfates) and cortisol metabolites was 1.5 and 1.3 times higher, respectively (P < 0.01 for all comparisons). The affected women also had significantly higher ratios of 11-oxo (oxygenated) metabolites to 11-hydroxy metabolites of cortisol (1.4 times higher, P < 0.001) and of 11-oxo to 11-hydroxy metabolites of corticosterone (1.8 times higher, P < 0.001). In the group with the polycystic ovary syndrome, 55 percent of the nonobese women and 24 percent of the obese women had ratios above the upper limit of normal; the ratios in the obese women did not differ significantly from those in the nonobese women. CONCLUSIONS Adrenal secretion of cortisol and androgens is increased in women with the polycystic ovary syndrome. The increases may be explained by dysregulation of 11 beta-hydroxysteroid dehydrogenase causing increased oxidation of cortisol to cortisone, which cannot be accounted for by obesity.
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Affiliation(s)
- A Rodin
- Division of Biochemical Medicine, St. George's Hospital Medical School, London, United Kingdom
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21
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Abstract
Pairs of antiparallely oriented consensus tRNAs with complementary anticodons show surprisingly small numbers of mispairings within the 17-bp- long anticodon stem and loop region. Even smaller such complementary distances are shown by illegitimately complementary anticodons, i.e. those with allowed pairing between G and U bases. Accordingly, we suppose that transfer RNAs have emerged concertedly as complementary strands of primordial double helix-like RNA molecules. Replication of such molecules with illegitimately complementary anticodons might generate new synonymous codons for the same pair of amino acids. Logically, the idea of tRNA concerted origin dictates very ancient establishment of direct links between anticodons and the type of amino acids with which pre-tRNAs were to be charged. More specifically, anticodons (first of all, the 2nd base) could selectively target 'their' amino acids, reaction of acylating itself being performed by another non-specific site of pre-tRNA or even by another ribozyme. In all, the above findings and speculations are consistent to the hypercyclic concept (Eigen and Schuster, 1979), and throw new light on the genetic code origin and associated problems. Also favoring this idea are data on complementary codon usage patterns in different genomes.
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Affiliation(s)
- S Rodin
- Institute of Cytology & Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk
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22
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Rodin S, Ohno S, Rodin A. Transfer RNAs with complementary anticodons: could they reflect early evolution of discriminative genetic code adaptors? Proc Natl Acad Sci U S A 1993; 90:4723-7. [PMID: 8506325 PMCID: PMC46585 DOI: 10.1073/pnas.90.10.4723] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
In accordance with the hypercycle theory of M. Eigen and P. Schuster [(1979) Hypercycle: A Principle of Natural Self-Organization (Springer, New York)], the ancestors of modern tRNAs appear to have emerged via the shortest possible way, both complementary strands of a short symmetrical double helix serving as pre-tRNAs with complementary anticodons. This conclusion is based upon results of comparative sequence analysis of the 17-base-long anticodon loop and stem of tRNAs totaling 896 and especially of 22 pairs of consensus tRNAs with complementary or quasi-complementary anticodons. With regard to the anticodon loop and stem of pairs of consensus tRNAs, complementary distances were considerably less than direct distances--i.e., antiparallel pairing invariably yielded fewer mismatches than direct pairing. Furthermore, the smallest complementary distance was detected when two antiparallel sequences formed irregular G-U bonds in their anticodon triplets. The above implies that pre-tRNAs in peribiotic times were long hairpin structures having 73 bases or more, the middle base of an anticodon being the center of symmetry. Accordingly, each pair of pre-tRNAs with complementary anticodons should have been almost identical with each other except for their three central bases. The above situation appears to have dictated the early establishment of direct links between anticodons and the type of amino acids with which tRNAs are to be charged. This direct link is still maintained between modern aminoacyl-tRNA synthetases and anticodons. Replication of the double helices concertedly generated new codons for the same pair of amino acids. Thus, occurrence of synonymous as well as certain "palindromic" features of the genetic code table might have been determined by this mechanism.
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Affiliation(s)
- S Rodin
- Institute of Cytology and Genetics, Siberian Branch of Russian Academy of Sciences, Novosibirsk
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23
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Abstract
The influence of subject repositioning on the precision of bone mineral densitometry of the proximal femur using dual energy X-ray absorptiometry was estimated by determining the variation in the bone mineral density (BMD) of subjects scanned with their foot and leg position varying from that routinely used in clinical scanning. The mean variations in BMD of the femoral neck, Ward's triangle and trochanter were 2.7, 4.1 and 1.7%, respectively, in eight subjects scanned with the foot internally rotated by 0, 13 and 27 degrees. The mean variations in BMD in four subjects scanned with the leg in the customary position and abducted +/- 6 degrees from the conventionally used scanning position were 3.6, 2.8 and 1.6% for the same respective regions of interest. For diagnostic applications, the orientation of the leg and foot during scanning is relatively unimportant since the variations in BMD introduced by the different foot and leg orientations likely to be encountered in routine clinical scanning are small compared to the intrapopulation variation in BMD. However, for monitoring changes in BMD longitudinally, careful repositioning of the foot and leg will be necessary to achieve precision in vivo of less than 1%.
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Affiliation(s)
- C R Wilson
- Department of Radiology, Medical College of Wisconsin, Milwaukee 53226
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24
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Rodin A, Key J. Lazarus complex (Lazarus syndrome, near-death syndrome). Ohio Med 1991; 87:150-1. [PMID: 2030887] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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25
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Rodin A, Key J. Job's syndrome (granulomatous disease variant). Ohio Med 1990; 86:742, 708. [PMID: 2234765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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26
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Rodin A, Key J. Janiceps twins. Ohio Med 1990; 86:666. [PMID: 2234774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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27
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Rodin A, Key J. Hypnosis. Ohio Med 1990; 86:544-5. [PMID: 2288577] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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28
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Rodin A, Key J. Humpty Dumpty etymology. Ohio Med 1990; 86:480. [PMID: 2367055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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29
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Rodin A, Key J. Gargoylism. Ohio Med 1990; 86:397. [PMID: 2111006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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30
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Rodin A, Key J. Faust complex. Ohio Med 1990; 86:320, 322. [PMID: 2183116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
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31
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Rodin A, Key J. Electra complex. Ohio Med 1990; 86:147. [PMID: 2314814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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32
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Abstract
Dual photon absorptiometry enables measurement of bone mineral to be carried out at the clinically relevant sites of the spine and femur. Few would argue that it provides a powerful research tool, but defining its role in clinical practice has been somewhat more difficult. With the advent of X-ray based systems, studies can be rapidly carried out with improved precision, which has led to increased clinical interest. It is probable that this technology will be incorporated into routine use in the near future. In the present review we have addressed the role of dual photon absorptiometry in areas pertinent to osteoporosis and the direction in which recent developments are leading with regard to future research.
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Abstract
Two hundred and twenty-five premenopausal women were studied to evaluate age-related changes in trabecular bone mass. Measurements were made at the lumbar spine and femoral neck by dual photon absorptiometry. It was found that spinal bone density increased significantly from the 20s to reach a peak in the mid-30s. Identical trends were observed in total bone mass and bone mass normalized by length. Bone loss then proceeded at a rate of 1% per year, and by the early 50s, 10% of peak spinal density was lost. There was no peak in femoral neck density; loss commenced in the late 20s and continued at a rate of 0.4% per year. The cumulative premenopausal loss from the femur at 9% was comparable to that in the spine. It is concluded that significant amounts of trabecular bone are lost from both the spine and femoral neck before the menopause. The implications of these findings for the prevention of osteoporosis are discussed.
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Affiliation(s)
- A Rodin
- Department of Gynaecology, Guy's Hospital, London, England
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34
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Rodin A. Cinderella dermatosis. Ohio Med 1989; 85:889-90. [PMID: 2601937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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35
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Abstract
Dual photon absorptiometry (DPA) has been used to measure the effect of short and medium-term administration of tamoxifen on bone density in the axial skeleton of women with mastalgia. This provided a unique opportunity to monitor the effect of this 'anti-oestrogenic' agent in predominantly premenopausal women, not suffering from malignancy. In addition, plasma levels of calcium, phosphate, alkaline phosphatase and serum levels of oesteocalcin (GLA) have been assayed, both before and after 3 months of starting either tamoxifen or placebo treatment. No significant alterations in bone density were seen. Osteocalcin, alkaline phosphatase and electrolytes were unchanged and there was no dose response observed in women receiving either 10 mg or 20 mg of tamoxifen. Although possessing anti-oestrogenic properties, tamoxifen is also a partial agonist. Administration for the short periods does not measurably influence spinal or femoral bone density and thus the agent can probably be given safely for the short-term treatment of mastalgia.
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Affiliation(s)
- I S Fentiman
- Department of Clinical Oncology, Guy's Hospital, London, UK
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36
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Affiliation(s)
- A Rodin
- Department of Obstetrics, Guy's Hospital, London
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37
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Rodin A, Duncan A, Quartero HW, Pistofidis G, Mashiter G, Whitaker K, Crook D, Stevenson JC, Chapman MG, Fogelman I. Serum concentrations of alkaline phosphatase isoenzymes and osteocalcin in normal pregnancy. J Clin Endocrinol Metab 1989; 68:1123-7. [PMID: 2786001 DOI: 10.1210/jcem-68-6-1123] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
We measured serum alkaline phosphatase isoenzymes and osteocalcin levels in 40 healthy women at 4-week intervals throughout uncomplicated pregnancies and 6 weeks after delivery in 17 women. Serum bone alkaline phosphatase was significantly higher in the third trimester than in early pregnancy (P less than 0.001), and this elevation was still apparent at the end of the puerperium, suggesting increased bone turnover. Serum osteocalcin was not detected (less than 0.2 micrograms/L) after the first trimester in the majority of women, and it reappeared within 48 h after delivery. The disappearance of osteocalcin after the first trimester and its rapid reappearance after delivery suggest placental clearance of this peptide. We conclude that serum osteocalcin measurements cannot be used as a marker of bone metabolism during pregnancy.
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Affiliation(s)
- A Rodin
- Department of Obstetrics, Guy's Hospital, London, England
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38
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Rodin A, Rodin A. Thyroid disease in pregnancy. Br J Hosp Med (Lond) 1989; 41:234, 238-42. [PMID: 2653540] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Thyroid disease may be pre-existing or rarely may arise de novo during pregnancy. It may have profound effects on the feto-maternal unit. Diagnosis depends on clinical suspicion and confirmation by biochemical tests of thyroid function. However, pregnancy masks the signs of thyroid disease and may alter the interpretation of thyroid function tests.
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Affiliation(s)
- A Rodin
- Endocrinology Research Group, MRC Clinical Research Centre, Harrow, London
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39
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Abstract
The spinal and femoral bone mass of 32 hirsute women with oligomenorrhoea and androgen excess was measured using dual photon absorptiometry and compared with the bone mass of 32 control women with regular menstrual cycles. Despite significantly lower oestradiol levels in the hirsute population there was no significant difference in the bone mass. Furthermore there was no significant difference in bone mass in five hirsute women with undetectable levels of oestradiol. It is concluded that androgen excess can maintain normal bone mass in the face of low or undetectable oestradiol levels.
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Affiliation(s)
- J E Dixon
- Department of Obstetrics and Gynaecology, Guy's Hospital, London, UK
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40
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Adinolfi M, Cheetham M, Lee T, Rodin A. Ontogeny of human complement receptors CR1 and CR3: expression of these molecules on monocytes and neutrophils from maternal, newborn and fetal samples. Eur J Immunol 1988; 18:565-9. [PMID: 2835247 DOI: 10.1002/eji.1830180412] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Higher levels of the expression of CR1 and CR3 molecules were detected on the surface of monocytes and neutrophils from maternal and newborn (cord) blood samples than in adult controls. Chemotactic factors such as formyl-methionyl-leucyl-phenylalanine or leukotriene B4 induced an increase of the expression of CR1 and CR3 which was more pronounced on cells from maternal and cord samples than from nonpregnant adult controls. CR1 and CR3 molecules were detected in monocytes and neutrophils from peripheral blood obtained from fetuses more than 14 weeks old and on subpopulations of cells in bone marrow, spleen and thymus.
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Affiliation(s)
- M Adinolfi
- Paediatric Research Unit, United Medical School, Guy's Hospital, London, GB
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41
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Ritter JM, Farquhar C, Rodin A, Thom MH. Low dose aspirin treatment in late pregnancy differentially inhibits cyclo-oxygenase in maternal platelets. Prostaglandins 1987; 34:717-22. [PMID: 3124218 DOI: 10.1016/0090-6980(87)90294-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Eighteen pregnant women were treated with aspirin, 37.5 mg once daily by mouth. Treatment was started two weeks before the expected date of delivery, and continued until delivery. Seventeen untreated women were studied concurrently. Platelet thromboxane (TX) production was determined by radioimmunoassay of TXB2 in serum from blood incubated for one hour with thrombin at 37 degrees C. Maternal blood was studied before treatment and at delivery. Fetal blood, from the cord, was studied at delivery. Prostacyclin (PGI2) production by rings of umbilical artery incubated in Hanks' solution at 37 degrees C for one hour was determined by radio-immunoassay of its hydrolysis product, 6-oxo-prostaglandin (PG) F1 alpha. Maternal and fetal blood from untreated women produced similar amounts of TXB2. Aspirin, in the dose regimen used, significantly inhibited TXB2 production in maternal but not in fetal blood, and did not impair PGI2 synthesis by umbilical artery rings. This differential effect on the cyclo-oxygenase of maternal platelets is probably due to the unusual kinetic properties of aspirin, and may prove therapeutically useful.
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Affiliation(s)
- J M Ritter
- Department of Clinical Pharmacology, Royal Postgraduate Medical School, London
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42
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Markert RJ, Barton J, Rodin A. CME. How is it measuring up? Ohio State Med J 1982; 78:409-10, 415-9. [PMID: 7110650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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