1
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Plett JM, Wojtalewicz D, Plett KL, Collin S, Kohler A, Jacob C, Martin F. Sesquiterpenes of the ectomycorrhizal fungus Pisolithus microcarpus alter root growth and promote host colonization. Mycorrhiza 2024; 34:69-84. [PMID: 38441669 PMCID: PMC10998793 DOI: 10.1007/s00572-024-01137-9] [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] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 02/01/2024] [Indexed: 04/07/2024]
Abstract
Trees form symbioses with ectomycorrhizal (ECM) fungi, maintained in part through mutual benefit to both organisms. Our understanding of the signaling events leading to the successful interaction between the two partners requires further study. This is especially true for understanding the role of volatile signals produced by ECM fungi. Terpenoids are a predominant class of volatiles produced by ECM fungi. While several ECM genomes are enriched in the enzymes responsible for the production of these volatiles (i.e., terpene synthases (TPSs)) when compared to other fungi, we have limited understanding of the biochemical products associated with each enzyme and the physiological impact of specific terpenes on plant growth. Using a combination of phylogenetic analyses, RNA sequencing, and functional characterization of five TPSs from two distantly related ECM fungi (Laccaria bicolor and Pisolithus microcarpus), we investigated the role of these secondary metabolites during the establishment of symbiosis. We found that despite phylogenetic divergence, these TPSs produced very similar terpene profiles. We focused on the role of P. microcarpus terpenes and found that the fungus expressed a diverse array of mono-, di-, and sesquiterpenes prior to contact with the host. However, these metabolites were repressed following physical contact with the host Eucalyptus grandis. Exposure of E. grandis to heterologously produced terpenes (enriched primarily in γ -cadinene) led to a reduction in the root growth rate and an increase in P. microcarpus-colonized root tips. These results support a very early putative role of fungal-produced terpenes in the establishment of symbiosis between mycorrhizal fungi and their hosts.
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Affiliation(s)
- Jonathan M Plett
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia.
| | - Dominika Wojtalewicz
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
| | - Krista L Plett
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, 2753, Australia
- Elizabeth Macarthur Agricultural Institute, NSW Department of Primary Industries, Menangle, NSW, 2568, Australia
| | - Sabrina Collin
- Université de Lorraine, CNRS, IMoPA, F-54000, Nancy, France
| | - Annegret Kohler
- Université de Lorraine, INRAE, UMR Interactions Arbres-Microorganismes, Centre INRAE Grand Est-Nancy, 54280, Champenoux, France
| | | | - Francis Martin
- Université de Lorraine, INRAE, UMR Interactions Arbres-Microorganismes, Centre INRAE Grand Est-Nancy, 54280, Champenoux, France
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2
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Minas HA, François RMM, Hemmerling F, Fraley AE, Dieterich CL, Rüdisser SH, Meoded RA, Collin S, Weissman KJ, Gruez A, Piel J. Modular Oxime Formation by a trans-AT Polyketide Synthase. Angew Chem Int Ed Engl 2023; 62:e202304481. [PMID: 37216334 DOI: 10.1002/anie.202304481] [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] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2023] [Revised: 05/16/2023] [Accepted: 05/22/2023] [Indexed: 05/24/2023]
Abstract
Modular trans-acyltransferase polyketide synthases (trans-AT PKSs) are enzymatic assembly lines that biosynthesize complex polyketide natural products. Relative to their better studied cis-AT counterparts, the trans-AT PKSs introduce remarkable chemical diversity into their polyketide products. A notable example is the lobatamide A PKS, which incorporates a methylated oxime. Here we demonstrate biochemically that this functionality is installed on-line by an unusual oxygenase-containing bimodule. Furthermore, analysis of the oxygenase crystal structure coupled with site-directed mutagenesis allows us to propose a model for catalysis, as well as identifying key protein-protein interactions that support this chemistry. Overall, our work adds oxime-forming machinery to the biomolecular toolbox available for trans-AT PKS engineering, opening the way to introducing such masked aldehyde functionalities into diverse polyketides.
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Affiliation(s)
- Hannah A Minas
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
| | - Romain M M François
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
- Université de Lorraine, CNRS, IMoPA, 54000, Nancy, France
| | - Franziska Hemmerling
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
| | - Amy E Fraley
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
| | - Cora L Dieterich
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
| | - Simon H Rüdisser
- Institute of Molecular Biology and Biophysics, Biomolecular NMR Spectroscopy Platform, Eidgenössische Technische Hochschule (ETH) Zürich, Hönggerbergring 64, 8093, Zürich, Switzerland
| | - Roy A Meoded
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
| | - Sabrina Collin
- Université de Lorraine, CNRS, IMoPA, 54000, Nancy, France
| | | | - Arnaud Gruez
- Université de Lorraine, CNRS, IMoPA, 54000, Nancy, France
| | - Jörn Piel
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH) Zürich, Vladimir-Prelog-Weg 4, 8093, Zürich, Switzerland
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3
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Brocart C, Beck J, Collin S, Lamy P, Sabouraud-Leclerc D. L’induction de tolérance orale à la noix de cajou et/ou à la pistache chez 50 patients : l’expérience rémoise. Revue Française d'Allergologie 2023. [DOI: 10.1016/j.reval.2022.103279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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4
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Raoult E, Bodeux R, Jutteau S, Rives S, Yaiche A, Blaizot A, Coutancier D, Rousset J, Collin S. Iterative method for optical modelling of perovskite-based tandem solar cells. Opt Express 2022; 30:9604-9622. [PMID: 35299384 DOI: 10.1364/oe.444698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 12/13/2021] [Indexed: 06/14/2023]
Abstract
We present an iterative method to model the optical properties of a complete semitransparent perovskite solar cell. It is based on spectroscopic characterizations and accounts for porosity and incoherence effects. We provide the complex refractive indices of each layer, and we identify the main sources of optical losses. The optical model is also coupled to an electrical model of 4T perovskite/silicon tandem solar cells. It allows to evaluate the interplay between the optical and electrical losses, and the balance between the efficiency of the top and bottom cells. These models provide an effective way to design future tandem devices.
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5
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Dusart A, Mertens B, Van Hoeck E, Simon M, Goscinny S, Collin S. Occurrence of (suspected) genotoxic flavoring substances in Belgian alcohol-free beers. Food Chem 2022; 369:130917. [PMID: 34464835 DOI: 10.1016/j.foodchem.2021.130917] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Revised: 08/11/2021] [Accepted: 08/17/2021] [Indexed: 11/04/2022]
Abstract
The regulatory landscape of flavorings is evolving, thereby putting pressure on control laboratories to develop analytical methods for a wide range of compounds in various types of food and drinks. In order to improve the monitoring of flavoring substances, a versatile and accurate analytical method using the solvent-assisted flavor evaporation (SAFE) technique coupled to GC-MS(SIM) was developed and validated. Focus was put on authorized flavoring substances requiring specific attention due to a genotoxic concern based on information from European risks assessment reports. Thirty-seven (suspected) genotoxic flavoring substances were analyzed in a selection of ten alcohol-free beers. Five suspected genotoxic compounds (i.e. 1-(2-furyl)-2-propanone, 2-acetylfuran, 2-acetyl-5-methylfuran, 2-acetyl-3,5-dimethylfuran, hex-2-eno-1,4-lactone) as well as two confirmed genotoxic flavoring substances (p-mentha-1,8-dien-7-al, 2,4-pentanedione) were identified and quantified among the selected samples. Low concentrations and natural occurrences of the identified compounds suggested that these were not added as such but rather originated from heat-treatments or from plant-based extracts.
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Affiliation(s)
- A Dusart
- Department of Chemical and Physical Health Risks, Sciensano, Rue Juliette Wytsman 14, 1050 Ixelles, Belgium.
| | - B Mertens
- Department of Chemical and Physical Health Risks, Sciensano, Rue Juliette Wytsman 14, 1050 Ixelles, Belgium
| | - E Van Hoeck
- Department of Chemical and Physical Health Risks, Sciensano, Rue Juliette Wytsman 14, 1050 Ixelles, Belgium
| | - M Simon
- Unité de Brasserie et des Industries Alimentaires, Louvain Institute of Biomolecular Science and Technology (LIBST), Faculté des Bioingénieurs, Université catholique de Louvain, Croix du Sud 2, Box L7.05.07, 1348 Louvain-la-Neuve, Belgium
| | - S Goscinny
- Department of Chemical and Physical Health Risks, Sciensano, Rue Juliette Wytsman 14, 1050 Ixelles, Belgium
| | - S Collin
- Unité de Brasserie et des Industries Alimentaires, Louvain Institute of Biomolecular Science and Technology (LIBST), Faculté des Bioingénieurs, Université catholique de Louvain, Croix du Sud 2, Box L7.05.07, 1348 Louvain-la-Neuve, Belgium
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6
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Zhang H, Piazza V, Neplokh V, Guan N, Bayle F, Collin S, Largeau L, Babichev A, Julien FH, Tchernycheva M. Correlated optical and electrical analyses of inhomogeneous core/shell InGaN/GaN nanowire light emitting diodes. Nanotechnology 2021; 32:105202. [PMID: 33142273 DOI: 10.1088/1361-6528/abc70e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The performance of core-shell InGaN/GaN nanowire (NW) light emitting diodes (LEDs) can be limited by wire-to-wire electrical inhomogeneities. Here we investigate an array of core-shell InGaN/GaN NWs which are morphologically identical, but present electrical dissimilarities in order to understand how the nanoscale phenomena observed in individual NWs affect the working performance of the whole array. The LED shows a low number of NWs (∼20%) producing electroluminescence under operating conditions. This is related to a presence of a potential barrier at the interface between the NW core and the radially grown n-doped layer, which differently affects the electrical properties of the NWs although they are morphologically identical. The impact of the potential barrier on the performance of the NW array is investigated by correlating multi-scanning techniques, namely electron beam induced current microscopy, electroluminescence mapping and cathodoluminescence analysis. It is found that the main cause of inhomogeneity in the array is related to a non-optimized charge injection into the active region, which can be overcome by changing the contact architecture so that the electrons become injected directly in the n-doped underlayer. The LED with so-called 'front-n-contacting' is developed leading to an increase of the yield of emitting NWs from 20% to 65%.
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Affiliation(s)
- H Zhang
- School of Microelectronics, Dalian University of Technology, 116024 Dalian, People's Republic of China
- C2N-CNRS, Univ. Paris Saclay, F-91120 Palaiseau, France
| | - V Piazza
- C2N-CNRS, Univ. Paris Saclay, F-91120 Palaiseau, France
- Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - V Neplokh
- C2N-CNRS, Univ. Paris Saclay, F-91120 Palaiseau, France
- National Research Academic University of the Russian Academy of Sciences, 194021, Saint Petersburg, Russia
| | - N Guan
- C2N-CNRS, Univ. Paris Saclay, F-91120 Palaiseau, France
| | - F Bayle
- C2N-CNRS, Univ. Paris Saclay, F-91120 Palaiseau, France
| | - S Collin
- C2N-CNRS, Univ. Paris Saclay, F-91120 Palaiseau, France
| | - L Largeau
- C2N-CNRS, Univ. Paris Saclay, F-91120 Palaiseau, France
| | - A Babichev
- ITMO University, 197101, Saint Petersburg, Russia
| | - F H Julien
- C2N-CNRS, Univ. Paris Saclay, F-91120 Palaiseau, France
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7
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Dorival J, Risser F, Jacob C, Collin S, Dräger G, Paris C, Chagot B, Kirschning A, Gruez A, Weissman KJ. Author Correction: Insights into a dual function amide oxidase/macrocyclase from lankacidin biosynthesis. Nat Commun 2020; 11:683. [PMID: 31996686 PMCID: PMC6989693 DOI: 10.1038/s41467-020-14473-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
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8
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Risser F, Collin S, Dos Santos-Morais R, Gruez A, Chagot B, Weissman KJ. Towards improved understanding of intersubunit interactions in modular polyketide biosynthesis: Docking in the enacyloxin IIa polyketide synthase. J Struct Biol 2020; 212:107581. [DOI: 10.1016/j.jsb.2020.107581] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Revised: 07/14/2020] [Accepted: 07/16/2020] [Indexed: 12/26/2022]
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9
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Worrillow N, South J, Cole A, Collin S, Briggs M. The frequent user’s decision-making process when contacting urgent and/or emergency services. Eur J Public Health 2020. [DOI: 10.1093/eurpub/ckaa165.1192] [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] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Background
There is a lack of qualitative research that has been undertaken which has captured the perspective of frequent users to urgent and emergency healthcare services. Previous research has viewed and studied this population largely by using retrospective routine data, which focuses on the patient's demographic, presenting symptom or demand implication. Current research now advocates that these vulnerable and complex individuals are using these services due to their unmet needs or multiple comorbidities. The aim of this research was to explore the patient's decision-making process and their motivations for repeatedly contacting urgent and emergency services.
Methods
Semi-structured interviews were undertaken with a small cohort of six previously identified frequent users to urgent and emergency healthcare services. These participants were recruited into the study by a third sector organisation, due to the vulnerabilities and complexities of these individuals' lifestyles. A framework analysis was used to code and extract relevant themes and concepts from the interviews.
Results
Social prescribing through a named support worker enables navigation and re-engagement into a range of services that benefits this population and reduces their demand upon other services. The support given through social prescribing organisations can counteract the lack of personal support networks and resilience factors that these individuals experience. In addition, individuals who have been re-referred into substance misuse services should be offered alternative engagement programmes, which differ from their initial programme.
Conclusions
Current inequities of outcomes and access to services should be examined, in relation to vulnerable and complex individuals who have reduced support networks and limited resilience factors. Future research should be undertaken regarding the benefits for frequent users of social prescribing to support patient outcomes and re-integration into services.
Key messages
Social prescribing is the link that enables complex and vulnerable frequent users to navigate and re-engage into a range of health and social care services. Examining the inequities faced by frequent users to urgent and emergency healthcare services.
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Affiliation(s)
- N Worrillow
- School of Health and Community Studies, Leeds Beckett University, Leeds, UK
| | - J South
- School of Health and Community Studies, Leeds Beckett University, Leeds, UK
| | - A Cole
- NHS Leeds Clinical Commissioning Group, Leeds, UK
- Urgent Care, Barca-Leeds, Leeds, UK
| | - S Collin
- Urgent Care, Barca-Leeds, Leeds, UK
- NHS Leeds Clinical Commissioning Group, Leeds, UK
| | - M Briggs
- School of Health Sciences, The University of Manchester, Manchester, UK
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10
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Rouco V, Hage RE, Sander A, Grandal J, Seurre K, Palermo X, Briatico J, Collin S, Trastoy J, Bouzehouane K, Buzdin AI, Singh G, Bergeal N, Feuillet-Palma C, Lesueur J, Leon C, Varela M, Santamaría J, Villegas JE. Quasiparticle tunnel electroresistance in superconducting junctions. Nat Commun 2020; 11:658. [PMID: 32005810 PMCID: PMC6994500 DOI: 10.1038/s41467-020-14379-w] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [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: 06/26/2019] [Accepted: 12/30/2019] [Indexed: 11/13/2022] Open
Abstract
The term tunnel electroresistance (TER) denotes a fast, non-volatile, reversible resistance switching triggered by voltage pulses in ferroelectric tunnel junctions. It is explained by subtle mechanisms connected to the voltage-induced reversal of the ferroelectric polarization. Here we demonstrate that effects functionally indistinguishable from the TER can be produced in a simpler junction scheme—a direct contact between a metal and an oxide—through a different mechanism: a reversible redox reaction that modifies the oxide’s ground-state. This is shown in junctions based on a cuprate superconductor, whose ground-state is sensitive to the oxygen stoichiometry and can be tracked in operando via changes in the conductance spectra. Furthermore, we find that electrochemistry is the governing mechanism even if a ferroelectric is placed between the metal and the oxide. Finally, we extend the concept of electroresistance to the tunnelling of superconducting quasiparticles, for which the switching effects are much stronger than for normal electrons. Besides providing crucial understanding, our results provide a basis for non-volatile Josephson memory devices. The non-volatile switching of tunnel electroresistance in ferroelectric junctions provides the basis for memory and neuromorphic computing devices. Rouco et al. show tunnel electroresistance in superconductor-based junctions that arises from a redox rather than ferroelectric mechanism and is enhanced by superconductivity.
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Affiliation(s)
- V Rouco
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France.,Grupo de Física de Materiales Complejos, Dpto. Física de Materiales, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - R El Hage
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France
| | - A Sander
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France
| | - J Grandal
- Grupo de Física de Materiales Complejos, Dpto. Física de Materiales, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - K Seurre
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France
| | - X Palermo
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France
| | - J Briatico
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France
| | - S Collin
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France
| | - J Trastoy
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France
| | - K Bouzehouane
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France
| | - A I Buzdin
- Université de Bordeaux, LOMA UMR CNRS 5798, F-33405, Talence, France
| | - G Singh
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, Université PSL, CNRS, 75005, Paris, France
| | - N Bergeal
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, Université PSL, CNRS, 75005, Paris, France
| | - C Feuillet-Palma
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, Université PSL, CNRS, 75005, Paris, France
| | - J Lesueur
- Laboratoire de Physique et d'Etude des Matériaux, ESPCI Paris, Université PSL, CNRS, 75005, Paris, France
| | - C Leon
- Grupo de Física de Materiales Complejos, Dpto. Física de Materiales, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - M Varela
- Grupo de Física de Materiales Complejos, Dpto. Física de Materiales, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - J Santamaría
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France.,Grupo de Física de Materiales Complejos, Dpto. Física de Materiales, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Javier E Villegas
- Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France.
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11
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Himwas C, Collin S, Chen HL, Patriarche G, Oehler F, Travers L, Saket O, Julien FH, Harmand JC, Tchernycheva M. Correlated optical and structural analyses of individual GaAsP/GaP core-shell nanowires. Nanotechnology 2019; 30:304001. [PMID: 30965307 DOI: 10.1088/1361-6528/ab1760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report on the structural and optical properties of GaAs0.7P0.3/GaP core-shell nanowires (NWs) for future photovoltaic applications. The NWs are grown by self-catalyzed molecular beam epitaxy. Scanning transmission electron microscopy (STEM) analyses demonstrate that the GaAsP NW core develops an inverse-tapered shape with a formation of an unintentional GaAsP shell having a lower P content. Without surface passivation, this unintentional shell produces no luminescence because of strong surface recombination. However, passivation of the surface with a GaP shell leads to the appearance of a secondary peak in the luminescence spectrum arising from this unintentional shell. The attribution of the luminescence peaks is confirmed by correlated cathodoluminescence and STEM analyses of the same NW.
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Affiliation(s)
- C Himwas
- Centre de Nanosciences et de Nanotechnologies, UMR 9001 CNRS, Univ. Paris Sud, Univ. Paris-Saclay, 10 Boulevard Thomas Gobert, F-91120 Palaiseau Cedex, France. Semiconductor Device Research Laboratory, Department of Electrical Engineering, Faculty of Engineering, Chulalongkorn University, 254 Phayathai Road, Bangkok 10330, Thailand
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12
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Dorival J, Risser F, Jacob C, Collin S, Dräger G, Paris C, Chagot B, Kirschning A, Gruez A, Weissman KJ. Insights into a dual function amide oxidase/macrocyclase from lankacidin biosynthesis. Nat Commun 2018; 9:3998. [PMID: 30266997 PMCID: PMC6162330 DOI: 10.1038/s41467-018-06323-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [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: 03/26/2018] [Accepted: 08/20/2018] [Indexed: 11/21/2022] Open
Abstract
Acquisition of new catalytic activity is a relatively rare evolutionary event. A striking example appears in the pathway to the antibiotic lankacidin, as a monoamine oxidase (MAO) family member, LkcE, catalyzes both an unusual amide oxidation, and a subsequent intramolecular Mannich reaction to form the polyketide macrocycle. We report evidence here for the molecular basis for this dual activity. The reaction sequence involves several essential active site residues and a conformational change likely comprising an interdomain hinge movement. These features, which have not previously been described in the MAO family, both depend on a unique dimerization mode relative to all structurally characterized members. Taken together, these data add weight to the idea that designing new multifunctional enzymes may require changes in both architecture and catalytic machinery. Encouragingly, however, our data also show LkcE to bind alternative substrates, supporting its potential utility as a general cyclization catalyst in synthetic biology. The monoamine oxidase family member LkcE is an enzyme from the lankacidin polyketide biosynthetic pathway, where it catalyzes an amide oxidation followed by an intramolecular Mannich reaction, yielding the polyketide macrocycle. Here the authors characterize LkcE and present several of its crystal structures, which explains the unusual dual activity of LkcE.
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Affiliation(s)
- Jonathan Dorival
- UMR 7365, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, Campus Biologie Santé, 9 Avenue de la Forêt de Haye, BP 20199, 54505, Vandœuvre-lès-Nancy Cedex, France.,Sorbonne Universités, UPMC Univ. Paris 06, CNRS, UMR 8227, Integrative Biology of Marine Models, Station Biologique de Roscoff, CS 90074, Roscoff, Bretagne, France
| | - Fanny Risser
- UMR 7365, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, Campus Biologie Santé, 9 Avenue de la Forêt de Haye, BP 20199, 54505, Vandœuvre-lès-Nancy Cedex, France
| | - Christophe Jacob
- UMR 7365, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, Campus Biologie Santé, 9 Avenue de la Forêt de Haye, BP 20199, 54505, Vandœuvre-lès-Nancy Cedex, France
| | - Sabrina Collin
- UMR 7365, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, Campus Biologie Santé, 9 Avenue de la Forêt de Haye, BP 20199, 54505, Vandœuvre-lès-Nancy Cedex, France
| | - Gerald Dräger
- Institut für Organische Chemie, Leibniz Universität Hannover, Schneiderberg 1B, Hannover, 30167, Germany
| | - Cédric Paris
- Laboratoire d'Ingénierie des Biomolécules, Ecole Nationale Supérieure d'Agronomie et des Industries Alimentaires (ENSAIA), Université de Lorraine, 2 Avenue de la Fôret de Haye, BP 172, 54518, Vandœuvre-lès-Nancy Cedex, France
| | - Benjamin Chagot
- UMR 7365, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, Campus Biologie Santé, 9 Avenue de la Forêt de Haye, BP 20199, 54505, Vandœuvre-lès-Nancy Cedex, France
| | - Andreas Kirschning
- Institut für Organische Chemie, Leibniz Universität Hannover, Schneiderberg 1B, Hannover, 30167, Germany
| | - Arnaud Gruez
- UMR 7365, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, Campus Biologie Santé, 9 Avenue de la Forêt de Haye, BP 20199, 54505, Vandœuvre-lès-Nancy Cedex, France.
| | - Kira J Weissman
- UMR 7365, Ingénierie Moléculaire et Physiopathologie Articulaire (IMoPA), CNRS-Université de Lorraine, Biopôle de l'Université de Lorraine, Campus Biologie Santé, 9 Avenue de la Forêt de Haye, BP 20199, 54505, Vandœuvre-lès-Nancy Cedex, France.
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Parrot A, Collin S, Bruylants G, Reinaud O. The 3 rd degree of biomimetism: associating the cavity effect, Zn II coordination and internal base assistance for guest binding and activation. Chem Sci 2018; 9:5479-5487. [PMID: 30079177 PMCID: PMC6048688 DOI: 10.1039/c8sc01129j] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [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: 03/09/2018] [Accepted: 05/29/2018] [Indexed: 12/12/2022] Open
Abstract
The synthesis and characterization of a resorcinarene-based tetra(imidazole) ligand is reported. The properties of the corresponding ZnII complex are studied in depth, notably by NMR spectroscopy. In MeCN, acid-base titration reveals that one out of the four imidazole arms is hemi-labile and can be selectively protonated, thereby opening a coordination site in the exo position. Quite remarkably, the 4th imidazole arm promotes binding of an acidic molecule (a carboxylic acid, a β-diketone or acetamide), by acting as an internal base, which allows guest binding as an anion to the metal center in the endo position. Most importantly, the presence of this labile imidazole arm makes the ZnII complex active for the catalyzed hydration of acetonitrile. It is proposed that it acts as a general base for activating a water molecule in the vicinity of the metal center during its nucleophilic attack to the endo-bound MeCN substrate. This system presents a unique degree of biomimetism when considering zinc enzymes: a pocket for guest binding, a similar first coordination sphere, a coordination site available for water activation in the cis position relative to the substrate and finally an internal imidazole residue that plays the role of a general base.
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Affiliation(s)
- A Parrot
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques , CNRS UMR8601 , Université Paris Descartes , Sorbonne Paris Cité , 45 rue des Saints Pères , 75006 Paris , France .
| | - S Collin
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques , CNRS UMR8601 , Université Paris Descartes , Sorbonne Paris Cité , 45 rue des Saints Pères , 75006 Paris , France .
| | - G Bruylants
- Engineering of Molecular NanoSystems , Ecole Polytechnique de Bruxelles , Université Libre de Bruxelles (ULB) , Avenue F. D. Roosevelt 50, CP165/64 , B-1050 Brussels , Belgium
| | - O Reinaud
- Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques , CNRS UMR8601 , Université Paris Descartes , Sorbonne Paris Cité , 45 rue des Saints Pères , 75006 Paris , France .
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14
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McVitie S, Hughes S, Fallon K, McFadzean S, McGrouther D, Krajnak M, Legrand W, Maccariello D, Collin S, Garcia K, Reyren N, Cros V, Fert A, Zeissler K, Marrows CH. A transmission electron microscope study of Néel skyrmion magnetic textures in multilayer thin film systems with large interfacial chiral interaction. Sci Rep 2018; 8:5703. [PMID: 29632330 PMCID: PMC5890272 DOI: 10.1038/s41598-018-23799-0] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [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: 11/22/2017] [Accepted: 03/21/2018] [Indexed: 12/05/2022] Open
Abstract
Skyrmions in ultrathin ferromagnetic metal (FM)/heavy metal (HM) multilayer systems produced by conventional sputtering methods have recently generated huge interest due to their applications in the field of spintronics. The sandwich structure with two correctly-chosen heavy metal layers provides an additive interfacial exchange interaction which promotes domain wall or skyrmion spin textures that are Néel in character and with a fixed chirality. Lorentz transmission electron microscopy (TEM) is a high resolution method ideally suited to quantitatively image such chiral magnetic configurations. When allied with physical and chemical TEM analysis of both planar and cross-sectional samples, key length scales such as grain size and the chiral variation of the magnetisation variation have been identified and measured. We present data showing the importance of the grain size (mostly < 10 nm) measured from direct imaging and its potential role in describing observed behaviour of isolated skyrmions (diameter < 100 nm). In the latter the region in which the magnetization rotates is measured to be around 30 nm. Such quantitative information on the multiscale magnetisation variations in the system is key to understanding and exploiting the behaviour of skyrmions for future applications in information storage and logic devices.
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Affiliation(s)
- S McVitie
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
| | - S Hughes
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - K Fallon
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - S McFadzean
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - D McGrouther
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom
| | - M Krajnak
- Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.,Department of Materials Science and Engineering, Monash University, Clayton, Victoria, 3800, Australia
| | - W Legrand
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - D Maccariello
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - S Collin
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - K Garcia
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - N Reyren
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - V Cros
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - A Fert
- Unité Mixte de Physique, CNRS, Thales, Univ. Paris-Sud, Université Paris-Saclay, 91767, Palaiseau, France
| | - K Zeissler
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom
| | - C H Marrows
- School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, United Kingdom
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15
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Lermusieau G, Noël S, Liégeois C, Collin S. Nonoxidative Mechanism for Development of Trans-2-Nonenal in Beer. Journal of the American Society of Brewing Chemists 2018. [DOI: 10.1094/asbcj-57-0029] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- G. Lermusieau
- Unité de Brasserie et des Industries Alimentaires, Université Catholique de Louvain, Place Croix du sud 2/Bte 7, B-1348 Louvain-la-Neuve, Belgium
| | - S. Noël
- Unité de Brasserie et des Industries Alimentaires, Université Catholique de Louvain, Place Croix du sud 2/Bte 7, B-1348 Louvain-la-Neuve, Belgium
| | - C. Liégeois
- Unité de Brasserie et des Industries Alimentaires, Université Catholique de Louvain, Place Croix du sud 2/Bte 7, B-1348 Louvain-la-Neuve, Belgium
| | - S. Collin
- Unité de Brasserie et des Industries Alimentaires, Université Catholique de Louvain, Place Croix du sud 2/Bte 7, B-1348 Louvain-la-Neuve, Belgium
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16
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Himwas C, Collin S, Rale P, Chauvin N, Patriarche G, Oehler F, Julien FH, Travers L, Harmand JC, Tchernycheva M. In situ passivation of GaAsP nanowires. Nanotechnology 2017; 28:495707. [PMID: 29057754 DOI: 10.1088/1361-6528/aa9533] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report on the structural and optical properties of GaAsP nanowires (NWs) grown by molecular-beam epitaxy. By adjusting the alloy composition in the NWs, the transition energy was tuned to the optimal value required for tandem III-V/silicon solar cells. We discovered that an unintentional shell was also formed during the GaAsP NW growth. The NW surface was passivated by an in situ deposition of a radial Ga(As)P shell. Different shell compositions and thicknesses were investigated. We demonstrate that the optimal passivation conditions for GaAsP NWs (with a gap of 1.78 eV) are obtained with a 5 nm thick GaP shell. This passivation enhances the luminescence intensity of the NWs by 2 orders of magnitude and yields a longer luminescence decay. The luminescence dynamics changes from single exponential decay with a 4 ps characteristic time in non-passivated NWs to a bi-exponential decay with characteristic times of 85 and 540 ps in NWs with GaP shell passivation.
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Affiliation(s)
- C Himwas
- Centre de Nanosciences et de Nanotechnologies-site Orsay, UMR 9001 CNRS, Univ. Paris Sud, Univ. Paris-Saclay, Bât 220, rue André Ampère, F-91405 Orsay, France
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17
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Dorival J, Annaval T, Risser F, Collin S, Roblin P, Jacob C, Gruez A, Chagot B, Weissman KJ. Characterization of Intersubunit Communication in the Virginiamycin trans-Acyl Transferase Polyketide Synthase. J Am Chem Soc 2016; 138:4155-67. [DOI: 10.1021/jacs.5b13372] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Jonathan Dorival
- UMR
7365, Ingénierie Moléculaire et Physiopathologie Articulaire
(IMoPA), CNRS-Université de Lorraine, Biopôle de l’Université de Lorraine, Campus Biologie Santé, 9
Avenue de la Forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy CEDEX, France
| | - Thibault Annaval
- UMR
7365, Ingénierie Moléculaire et Physiopathologie Articulaire
(IMoPA), CNRS-Université de Lorraine, Biopôle de l’Université de Lorraine, Campus Biologie Santé, 9
Avenue de la Forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy CEDEX, France
| | - Fanny Risser
- UMR
7365, Ingénierie Moléculaire et Physiopathologie Articulaire
(IMoPA), CNRS-Université de Lorraine, Biopôle de l’Université de Lorraine, Campus Biologie Santé, 9
Avenue de la Forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy CEDEX, France
| | - Sabrina Collin
- UMR
7365, Ingénierie Moléculaire et Physiopathologie Articulaire
(IMoPA), CNRS-Université de Lorraine, Biopôle de l’Université de Lorraine, Campus Biologie Santé, 9
Avenue de la Forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy CEDEX, France
| | - Pierre Roblin
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin BP 48, 91192 Gif-sur-Yvette CEDEX, France
- UR1268 Biopolymères, Interactions Assemblages (BIA), INRA, Rue de la Géraudière
BP 71627, 44316 Nantes CEDEX 3, France
| | - Christophe Jacob
- UMR
7365, Ingénierie Moléculaire et Physiopathologie Articulaire
(IMoPA), CNRS-Université de Lorraine, Biopôle de l’Université de Lorraine, Campus Biologie Santé, 9
Avenue de la Forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy CEDEX, France
| | - Arnaud Gruez
- UMR
7365, Ingénierie Moléculaire et Physiopathologie Articulaire
(IMoPA), CNRS-Université de Lorraine, Biopôle de l’Université de Lorraine, Campus Biologie Santé, 9
Avenue de la Forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy CEDEX, France
| | - Benjamin Chagot
- UMR
7365, Ingénierie Moléculaire et Physiopathologie Articulaire
(IMoPA), CNRS-Université de Lorraine, Biopôle de l’Université de Lorraine, Campus Biologie Santé, 9
Avenue de la Forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy CEDEX, France
| | - Kira J. Weissman
- UMR
7365, Ingénierie Moléculaire et Physiopathologie Articulaire
(IMoPA), CNRS-Université de Lorraine, Biopôle de l’Université de Lorraine, Campus Biologie Santé, 9
Avenue de la Forêt de Haye, CS 50184, 54505 Vandœuvre-lès-Nancy CEDEX, France
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Collin S, Anselmi A, Verhoye J, Haigron P, Flecher E. Virtual positioning of ventricular assist device for implantation planning. Ing Rech Biomed 2015. [DOI: 10.1016/j.irbm.2015.09.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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19
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Chitty S, Ghani R, Roe J, Davidson H, Routledge M, Edwards T, Hateley C, Collin S, Ritchie A, Dzvova J, Buckley J, Davidson R, John L. P190 Drug Induced Liver Injury In The Treatment Of Tuberculosis In A Busy Uk Centre. Thorax 2014. [DOI: 10.1136/thoraxjnl-2014-206260.319] [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: 11/03/2022]
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20
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Krachmalnicoff V, Cao D, Cazé A, Castanié E, Pierrat R, Bardou N, Collin S, Carminati R, De Wilde Y. Towards a full characterization of a plasmonic nanostructure with a fluorescent near-field probe. Opt Express 2013; 21:11536-11545. [PMID: 23670010 DOI: 10.1364/oe.21.011536] [Citation(s) in RCA: 4] [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: 06/02/2023]
Abstract
We report on the experimental and theoretical study of the spatial fluctuations of the local density of states (EM-LDOS) and of the fluorescence intensity in the near-field of a gold nanoantenna. EM-LDOS, fluorescence intensity and topography maps are acquired simultaneously by scanning a fluorescent nanosource grafted on the tip of an atomic force microscope at the surface of the sample. The results are in good quantitative agreement with numerical simulations. This work paves the way for a full near-field characterization of an optical nanoantenna.
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Affiliation(s)
- V Krachmalnicoff
- Institut Langevin, ESPCI ParisTech & CNRS UMR 7587, 1 rue Jussieu, 75005 Paris, France.
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21
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Fischer B, Boutserin S, Mazon H, Collin S, Branlant G, Gruez A, Talfournier F. Catalytic properties of a bacterial acylating acetaldehyde dehydrogenase: evidence for several active oligomeric states and coenzyme A activation upon binding. Chem Biol Interact 2012; 202:70-7. [PMID: 23237860 DOI: 10.1016/j.cbi.2012.11.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Revised: 11/02/2012] [Accepted: 11/06/2012] [Indexed: 10/27/2022]
Abstract
Until the last decade, two unrelated aldehyde dehydrogenase (ALDH) superfamilies, i.e. the phosphorylating and non-phosphorylating superfamilies, were known to catalyze the oxidation of aldehydes to activated or non-activated acids. However, a third one was discovered by the crystal structure of a bifunctional enzyme 4-hydroxy-2-ketovalerate aldolase/acylating acetaldehyde dehydrogenase (DmpFG) from Pseudomonas sp. strain CF600 (Manjasetty et al., Proc. Natl. Acad. Sci. USA 100 (2003) 6992-6997). Indeed, DmpF exhibits a non-phosphorylating CoA-dependent ALDH activity, but is structurally related to the phosphorylating superfamily. In this study, we undertook the characterization of the catalytic and structural properties of MhpEF from Escherichia coli, an ortholog of DmpFG in which MhpF converts acetaldehyde, produced by the cleavage of 4-hydroxy-2-ketovalerate by MhpE, into acetyl-CoA. The kinetic data obtained under steady-state and pre-steady-state conditions show that the aldehyde dehydrogenase, MhpF, is active as a monomer, a unique feature relative to the phosphorylating and non-phosphorylating ALDH superfamilies. Our results also reveal that the catalytic properties of MhpF are not dependent on its oligomeric state, supporting the hypothesis of a structurally and catalytically independent entity. Moreover, the transthioesterification is shown to be rate-limiting and, when compared with a chemical model, its catalytic efficiency is increased 10(4)-fold. Therefore, CoA binding to MhpF increases its reactivity and optimizes its positioning relative to the thioacylenzyme intermediate, thus enabling the formation of an efficient deacylation complex.
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Affiliation(s)
- Baptiste Fischer
- Unité Mixte de Recherche CNRS-Université de Lorraine 7214 AREMS, ARN-RNP Structure-Fonction-Maturation, Enzymologie Moléculaire et Structurale, Faculté de médecine, Biopôle, Vandœuvre-lès-Nancy, France
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Bibes M, Reyren N, Lesne E, George JM, Deranlot C, Collin S, Barthélémy A, Jaffrès H. Towards electrical spin injection into LaAlO3-SrTiO3. Philos Trans A Math Phys Eng Sci 2012; 370:4958-4971. [PMID: 22987038 DOI: 10.1098/rsta.2012.0201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Future spintronics devices will be built from elemental blocks allowing the electrical injection, propagation, manipulation and detection of spin-based information. Owing to their remarkable multi-functional and strongly correlated character, oxide materials already provide such building blocks for charge-based devices such as ferroelectric field-effect transistors (FETs), as well as for spin-based two-terminal devices such as magnetic tunnel junctions, with giant responses in both cases. Until now, the lack of suitable channel materials and the uncertainty of spin-injection conditions in these compounds had however prevented the exploration of similar giant responses in oxide-based lateral spin transport structures. In this paper, we discuss the potential of oxide-based spin FETs and report magnetotransport data that suggest electrical spin injection into the LaAlO(3)-SrTiO(3) interface system. In a local, three-terminal measurement scheme, we analyse the voltage variation associated with the precession of the injected spin accumulation driven by perpendicular or longitudinal magnetic fields (Hanle and 'inverted' Hanle effects). The spin accumulation signal appears to be much larger than expected, probably owing to amplification effects by resonant tunnelling through localized states in the LaAlO(3). We give perspectives on how to achieve direct spin injection with increased detection efficiency, as well on the implementation of efficient top gating schemes for spin manipulation.
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Affiliation(s)
- M Bibes
- Unité Mixte de Physique CNRS-Thales, Palaiseau, France.
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Bröhan M, Jerkovic V, Wilmotte R, Collin S. Catechins and Derived Procyanidins in Red and White Sorghum: Their Contributions to Antioxidant Activity. Journal of the Institute of Brewing 2012. [DOI: 10.1002/j.2050-0416.2011.tb00510.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Reyren N, Bibes M, Lesne E, George JM, Deranlot C, Collin S, Barthélémy A, Jaffrès H. Gate-controlled spin injection at LaAlO3/SrTiO3 interfaces. Phys Rev Lett 2012; 108:186802. [PMID: 22681101 DOI: 10.1103/physrevlett.108.186802] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2011] [Indexed: 06/01/2023]
Abstract
We report results of electrical spin injection at the high-mobility quasi-two-dimensional electron system (2-DES) that forms at the LaAlO3/SrTiO3 interface. In a nonlocal, three-terminal measurement geometry, we analyze the voltage variation associated with the precession of the injected spin accumulation driven by perpendicular or transverse magnetic fields (Hanle and inverted Hanle effect). The influence of bias and back-gate voltages reveals that the spin accumulation signal is amplified by resonant tunneling through localized states in the LaAlO3 strongly coupled to the 2-DES by tunneling transfer.
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Affiliation(s)
- N Reyren
- Unité Mixte de Physique CNRS-Thales, 1 Av. A. Fresnel, 91767 Palaiseau, France
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Andriamiadamanana C, Ferrier A, Lombez L, Joudrier AL, Naghavi N, Ghenuche P, Bardou N, Pellouard JL, Collin S, Pelle F, Guillemoles JF. Plasmonic enhancement of up-conversion in ultrathin layers. ACTA ACUST UNITED AC 2012. [DOI: 10.1117/12.908541] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
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Suck SY, Collin S, Bardou N, De Wilde Y, Tessier G. Imaging the three-dimensional scattering pattern of plasmonic nanodisk chains by digital heterodyne holography. Opt Lett 2011; 36:849-51. [PMID: 21403705 DOI: 10.1364/ol.36.000849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Nanoantennas have the unique ability to affect the emission pattern of a dipole in free space. We present a technique based on full-field heterodyne holography for the mapping of the scattered field of plasmonic gold nanodisk chains in all three dimensions. A spectroscopic study allowed us to determine the resonant and nonresonant wavelengths at which we conducted a full characterization of the scattered field on a chosen nanodisk chain.
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Affiliation(s)
- S Y Suck
- Institut Langevin, ESPCI ParisTech, CNRS, Université Pierre et Marie Curie, Paris, France.
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27
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Levy B, Collin S, Sennoun N, Ducrocq N, Kimmoun A, Asfar P, Perez P, Meziani F. Vascular hyporesponsiveness to vasopressors in septic shock: from bench to bedside. Intensive Care Med 2010; 36:2019-29. [PMID: 20862451 DOI: 10.1007/s00134-010-2045-8] [Citation(s) in RCA: 147] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Accepted: 08/24/2010] [Indexed: 01/20/2023]
Abstract
PURPOSE To delineate some of the characteristics of septic vascular hypotension, to assess the most commonly cited and reported underlying mechanisms of vascular hyporesponsiveness to vasoconstrictors in sepsis, and to briefly outline current therapeutic strategies and possible future approaches. METHODS Source data were obtained from a PubMed search of the medical literature with the following MeSH terms: Muscle, smooth, vascular/physiopathology; hypotension/etiology; shock/physiopathology; vasodilation/physiology; shock/therapy; vasoconstrictor agents. RESULTS Nitric oxide (NO) and peroxynitrite are crucial components implicated in vasoplegia and vascular hyporeactivity. Vascular ATP-sensitive and calcium-activated potassium channels are activated during shock and participate in hypotension. In addition, shock state is characterized by inappropriately low plasma glucocorticoid and vasopressin concentrations, a dysfunction and desensitization of alpha-receptors, and an inactivation of catecholamines by oxidation. Numerous other mechanisms have been individualized in animal models, the great majority of which involve NO: MEK1/2-ERK1/2 pathway, H(2)S, hyperglycemia, and cytoskeleton dysregulation associated with decreased actin expression. CONCLUSIONS Many therapeutic approaches have proven their efficiency in animal models, especially therapies directed against one particular compound, but have otherwise failed when used in human shock. Nevertheless, high doses of catecholamines, vasopressin and terlipressin, hydrocortisone, activated protein C, and non-specific shock treatment have demonstrated a partial efficiency in reversing sepsis-induced hypotension.
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Affiliation(s)
- B Levy
- Groupe Choc, Contrat Avenir INSERM 2006, Faculté de Médecine, Nancy Université, 9 Avenue de la Forêt de Haye, BP 184, Vandœuvre-lès-Nancy Cedex, 54505, France.
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Collin S, Baudoux G, Evrard G, Durant F. Molecular Structure Analysis of Benzamide Neuroleptics and Analogs. XII: (Exo)-2, 3-dimethoxy-N-[8]-(Phenylmethyl)-8 -AZA -Bicyclo [3.2.1] Oct - 3 - YL] Thiobenzamide, Hydrochloride. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/bscb.19870960806] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Callemien D, Collin S. Structure, Organoleptic Properties, Quantification Methods, and Stability of Phenolic Compounds in Beer—A Review. Food Reviews International 2009. [DOI: 10.1080/87559120903157954] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Barbara A, Le Perchec J, Collin S, Sauvan C, Pelouard JL, López-Ríos T, Quémerais P. Generation and control of hot spots on commensurate metallic gratings. Opt Express 2008; 16:19127-19135. [PMID: 19582005 DOI: 10.1364/oe.16.019127] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
We study the light localization on commensurate arrangements of deep metallic sub-wavelength grooves. We theoretically show that as the degree of commensuration tends to an irrational number new light localization states are produced. These have properties close to that reported for hot spots on disordered surfaces and are not permitted for simple period gratings. Existence of these new resonances is experimentally provided in the infra-red region by reflectivity measurements performed on two commensurate samples with respectively two and three slits per period. Manipulations of these hot spots which can be controlled from far-field could be used for high sensitivity spectroscopy applications.
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Affiliation(s)
- A Barbara
- Institut Néel, CNRS et Université Joseph Fourier, Grenoble, France.
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Abstract
BACKGROUND Surgery has been the treatment of choice for localized esophageal cancer. A number of studies have investigated whether preoperative chemotherapy followed by surgery leads to an improvement in cure rates but the individual reports have been conflicting. An explicit systematic update of the role of preoperative chemotherapy in the treatment of resectable thoracic esophageal cancer is, therefore, warranted. OBJECTIVES The objective of this review is to determine the role of preoperative chemotherapy on patients with resectable thoracic esophageal carcinomas. SEARCH STRATEGY Trials were identified by searching the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (1966 to 2006), EMBASE (1988 to 2006) and CANCERLIT (1993 to 2002). There were no language restrictions. SELECTION CRITERIA All trials of patients with potentially resectable carcinomas of the esophagus (of any histologic type) who were randomised to having either chemotherapy or no chemotherapy before surgery. DATA COLLECTION AND ANALYSIS The primary outcome was survival, which was assessed using hazard ratios. This is an amendment to the original review which used relative risks to assess survival at yearly intervals. Hazard ratios (HR) have now been introduced to summarise the complete survival experience in a single analysis. The risk ratio (relative risk; RR) was used to compare rates of resections, tumour recurrences and treatment morbidity and mortality. MAIN RESULTS There were eleven randomised trials involving 2019 patients. Eight trials (1729 patients) reported sufficient detail on survival to be included in a meta-analysis for the primary outcome. There was some evidence to suggest that preoperative chemotherapy improves survival, but this was inconclusive (HR 0.88; 95% CI 0.75 to 1.04). There was no evidence to suggest that the overall rate of resections (RR 0.96, 95% CI 0.92 to 1.01) or the rate of complete resections (R0) (RR 1.05; 95% CI 0.97 to 1.15) differ between the preoperative chemotherapy arm and surgery alone. There is no evidence that tumour recurrence (RR 0.81, 95% CI 0.54 to 1.22) or non-fatal complication rates (RR 0.90; 95% CI 0.76 to 1.06) differ for preoperative chemotherapy compared to surgery alone. Trials reported risks of toxicity with chemotherapy that ranged from 11% to 90%. AUTHORS' CONCLUSIONS In summary, preoperative chemotherapy plus surgery may offer a survival advantage compared to surgery alone for resectable thoracic esophageal cancer, but the evidence is inconclusive. There is some evidence of toxicity and preoperative mortality associated with chemotherapy.
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Affiliation(s)
- R A Malthaner
- University of Western Ontario, Division of Thoracic Surgery, London Health Sciences Centre, 375 South Street, Suite N345, London, Ontario, Canada N6A 4G5.
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Affiliation(s)
- I R Schwab
- University of California Davis, Sacramento, CA 95817, USA.
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Abstract
Polyfunctional thiols are known to have a strong impact on the overall aroma of many fermented foods. Surprisingly, very little data is available on their occurrence in beer. A specific extraction with p-hydroxymercuribenzoic acid was performed on four different fresh light-protected lager beers. gas chromatography-olfactometry, gas chromatography-mass spectrometry, and gas chromatography-pulsed-flame photometer detector analyses of the extracts revealed the presence of more than 10 polyfunctional thiols. All of them were absent from wort, suggesting a key role of the H(2)S excreted by yeasts. 3-Methyl-2-buten-1-thiol, 2-mercapto-3-methylbutanol, 3-mercapto-3-methylbutanol seem to be created from hop allylic alcohols via four different mechanisms: nucleophilic substitution, addition-elimination, and radical anti-Markovnikov or electrophilic Markovnikov additions. 1,4 Addition of hydrogen sulfide to wort alpha,beta-unsaturated aldehydes or ketones may explain the synthesis of 1-mercapto-3-pentanol, 3-mercaptohexanol, and 4-mercapto-4-methyl-2-pentanone through fermentation. Finally, 2-mercaptoethanol, 3-mercaptopropanol, and their corresponding acetates may derive from Ehrlich degradation of sulfur amino acids, while 2-methyl-3-furanthiol should be logically issued from Maillard reactions.
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Affiliation(s)
- C Vermeulen
- Université Catholique de Louvain, Unité de Brasserie et des Industries Alimentaires, Croix du Sud 2 Bte 7, B-1348 Louvain-la-Neuve, Belgium
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Dahdouh-Guebas F, Collin S, Lo Seen D, Rönnbäck P, Depommier D, Ravishankar T, Koedam N. Analysing ethnobotanical and fishery-related importance of mangroves of the East-Godavari Delta (Andhra Pradesh, India) for conservation and management purposes. J Ethnobiol Ethnomed 2006; 2:24. [PMID: 16681845 PMCID: PMC1475843 DOI: 10.1186/1746-4269-2-24] [Citation(s) in RCA: 7] [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] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2006] [Accepted: 05/08/2006] [Indexed: 05/09/2023]
Abstract
Mangrove forests, though essentially common and wide-spread, are highly threatened. Local societies along with their knowledge about the mangrove also are endangered, while they are still underrepresented as scientific research topics. With the present study we document local utilization patterns, and perception of ecosystem change. We illustrate how information generated by ethnobiological research can be used to strengthen the management of the ecosystem. This study was conducted in the Godavari mangrove forest located in the East-Godavari District of the state Andhra Pradesh in India, where mangroves have been degrading due to over-exploitation, extensive development of aquaculture, and pollution from rural and urbanized areas (Kakinada).One hundred interviews were carried out among the fisherfolk population present in two mangrove zones in the study area, a wildlife sanctuary with strong conservation status and an adjacent zone. Results from the interviews indicated that Avicennia marina (Forsk.) Vierh., a dominant species in the Godavari mangroves, is used most frequently as firewood and for construction. Multiple products of the mangrove included the bark of Ceriops decandra (Griff.) Ding Hou to dye the fishing nets and improve their durability, the bark of Aegiceras corniculatum (L.) Blanco to poison and catch fish, and the leaves of Avicennia spp. and Excoecaria agallocha L. as fodder for cattle. No medicinal uses of true mangrove species were reported, but there were a few traditional uses for mangrove associates. Utilization patterns varied in the two zones that we investigated, most likely due to differences in their ecology and legal status. The findings are discussed in relation with the demographic and socio-economic traits of the fisherfolk communities of the Godavari mangroves and indicate a clear dependency of their livelihood on the mangrove forest.Reported changes in the Godavari mangrove cover also differed in the two zones, with significantly less perceptions of a decrease in the protected area, as compared to the adjacent non-protected area. A posteriori comparisons between sequential satellite imagery (retrospective till 1977) and respondents that were at least 15 years back then, revealed a mangrove decrease which was however perceived to different extents depending on the area with which the fishermen were familiar. While local needs had not been incorporated in the existing policy, we created a framework on how data on ethnobotanical traditions, fishery-related activities and local people's perceptions of change can be incorporated into management strategies.
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Affiliation(s)
- F Dahdouh-Guebas
- Biocomplexity Research Team, c/o, Mangrove Management Group, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - S Collin
- Biocomplexity Research Team, c/o, Mangrove Management Group, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
| | - D Lo Seen
- Institut Français de Pondichéry, Rue St. Louis 11, BP 33, 605001 Pondicherry, India
| | - P Rönnbäck
- Department of Systems Ecology, University of Stockholm, Frescati Backe, S-106 91 Stockholm, Sweden
| | - D Depommier
- Institut Français de Pondichéry, Rue St. Louis 11, BP 33, 605001 Pondicherry, India
| | - T Ravishankar
- M.S. Swaminathan Research Foundation, Regional Office, 7-5A-2/1 Gopalakrishna Street, Ramaraopet, 533004 Kakinada, Andhra Pradesh, India
| | - N Koedam
- Laboratory of General Botany and Nature Management, Mangrove Management Group, Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels, Belgium
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Merano M, Sonderegger S, Crottini A, Collin S, Renucci P, Pelucchi E, Malko A, Baier MH, Kapon E, Deveaud B, Ganière JD. Probing carrier dynamics in nanostructures by picosecond cathodoluminescence. Nature 2005; 438:479-82. [PMID: 16306988 DOI: 10.1038/nature04298] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2005] [Accepted: 09/15/2005] [Indexed: 11/08/2022]
Abstract
Picosecond and femtosecond spectroscopy allow the detailed study of carrier dynamics in nanostructured materials. In such experiments, a laser pulse normally excites several nanostructures at once. However, spectroscopic information may also be acquired using pulses from an electron beam in a modern electron microscope, exploiting a phenomenon called cathodoluminescence. This approach offers several advantages. The multimode imaging capabilities of the electron microscope enable the correlation of optical properties (via cathodoluminescence) with surface morphology (secondary electron mode) at the nanometre scale. The broad energy range of the electrons can excite wide-bandgap materials, such as diamond- or gallium-nitride-based structures that are not easily excited by conventional optical means. But perhaps most intriguingly, the small beam can probe a single selected nanostructure. Here we apply an original time-resolved cathodoluminescence set-up to describe carrier dynamics within single gallium-arsenide-based pyramidal nanostructures with a time resolution of 10 picoseconds and a spatial resolution of 50 nanometres. The behaviour of such charge carriers could be useful for evaluating elementary components in quantum computers, optical quantum gates or single photon sources for quantum cryptography.
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Affiliation(s)
- M Merano
- Institute of Quantum Electronics and Photonics, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne-EPFL, Switzerland.
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Abstract
We describe the implementation of a glucose control protocol supported by a web-based insulin dose calculator in a 16-bedded intensive care unit. The protocol was introduced and then modified after 15 months' use. Glucose concentrations were retrospectively reviewed and compared for the 9-month period before introduction of the protocol (288 patients), for 15 months after its introduction (502 patients) and for a further 5 months after its modification to increase insulin dose (101 patients). The mean (SD) blood glucose concentrations decreased from 7.3 (1.8) mmol.l(-1) to 6.6 (1.6) mmol.l(-1) and then to 6.2 (1.3) mmol.l(-1). The proportion of values < 8.0 mmol.l(-1) increased from 69% to 81% and then to 89%. Blood glucose concentrations were increased by the use of intravenous nutrition and by vasoactive drugs but not by the administration of propofol. The odds ratio [95% CI] for death for glucose values > 8.0 mmol.l(-1) was 2.10 [1.19-3.73] compared to values < 6.1 mmol.l(-1). However, patient mortality remained constant during the study. Glycaemic control was improved outside a research setting using a protocol supported by a web-based insulin dose calculator.
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Affiliation(s)
- A N Thomas
- Intensive Care Unit, Hope Hospital, Stott Lane, Salford, M6 8HD, UK.
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Laroche M, Arnold C, Marquier F, Carminati R, Greffet JJ, Collin S, Bardou N, Pelouard JL. Highly directional radiation generated by a tungsten thermal source. Opt Lett 2005; 30:2623-5. [PMID: 16208920 DOI: 10.1364/ol.30.002623] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
We report the design of a tungsten thermal source with extraordinarily high directivity in the near infrared, comparable to the directivity of a CO2 laser. This high directivity is the signature of the long-range correlation of the electromagnetic field in the source plane. This phenomenon is due to the resonant thermal excitation of surface-plasmon polaritons.
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Affiliation(s)
- M Laroche
- Laboratoire d'Energétique Moléculaire et Macroscopique, Combustion, Ecole Centrale Paris, Centre National de la Recherche Scientifique, 92295 Châtenay-Malabry Cedex, France.
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Ustianowski A, Shaffer R, Collin S, Wilkinson RJ, Davidson RN. Prevalence and associations of vitamin D deficiency in foreign-born persons with tuberculosis in London. J Infect 2005; 50:432-7. [PMID: 15907552 DOI: 10.1016/j.jinf.2004.07.006] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/25/2004] [Indexed: 11/20/2022]
Abstract
OBJECTIVES The incidence of tuberculosis (TB) is high amongst foreign-born persons resident in developed countries. Vitamin D is important in the host defence against TB in vitro and deficiency may be an acquired risk factor for this disease. We aimed to determine the incidence and associations of vitamin D deficiency in TB patients diagnosed at an infectious diseases unit in London, UK. METHODS Case-note analysis of 210 unselected patients diagnosed with TB who had plasma vitamin D (25(OH)D3) levels routinely measured. Prevalence of 25(OH)D3 deficiency and its relationship to ethnic origin, religion, site of TB, sex, age, duration in the UK, month of 25(OH)D3 estimation and TB diagnosis were determined. RESULTS Of 210 patients 76% were 25(OH)D3 deficient and 56% had undetectable levels. 70/82 Indian, 24/28 East African Asian, 29/34 Somali, 14/19 Pakistani and Afghani, 16/22 Sri Lankan and 2/6 other African patients were deficient (with 58, 17, 23, 9, 6 and 1 having undetectable levels, respectively). Only 0/6 white Europeans and 1/8 Chinese/South East Asians had low plasma 25(OH)D3 levels. Muslims, Hindus and Sikhs all had equivalent rates of deficiency though Hindus were more likely to have undetectable levels (odds ratio 1.87, 95% CI 1.27-2.76). There was no significant association between 25(OH)D3 level and site of TB or duration of residence in the UK. There was no apparent seasonal variation in either TB diagnosis or 25(OH)D3 level. CONCLUSIONS 25(OH)D3 deficiency commonly associates with TB among all ethnic groups apart from white Europeans, and Chinese/South East Asians. Our data support a lack of sunlight exposure and potentially a vegetarian diet as contributors to this deficiency.
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Affiliation(s)
- A Ustianowski
- Department of Infection and Tropical Medicine, Lister Unit, Northwick Park Hospital, Harrow, Middlesex HA1 3UJ, UK.
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Marquier F, Greffet J, Collin S, Pardo F, Pelouard J. Resonant transmission through a metallic film due to coupled modes. Opt Express 2005; 13:70-76. [PMID: 19488328 DOI: 10.1364/opex.13.000070] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Enhanced transmission and absorption by a silver film with a periodic array of slits has been studied numerically. We find that transmission and absorption peaks coincide and can be attributed to resonances of the structure. We show that these modes can be viewed as a coupling between cavity modes and surface plasmon polaritons. A quantitative analysis shows that the coupled mode can have a cavity mode character or a surface plasmon character depending on the distance to the crossing point of their dispersion relation. Finally, we provide a simple model for the peak transmission value by introducing the concept of radiative yield.
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Falls D, Stevens J, Andersen M, Collin S, Dodd N, Fitzgerald E, Mitchell G, Ramsay A, Sheriden J, Weaver A, Wilson V. Carers' perceptions of pain in people with dementia: a grounded theory approach. Aust J Holist Nurs 2004; 11:4-11. [PMID: 19175252] [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] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The purpose of this Grounded Theory based study was to add to the limited understanding about the perception and observation of pain by the formal and informal carers of people with dementia. Thirty-one carers talked about how they know when their person with dementia has pain. Findings showed there is no one set of signs or behaviours that indicate pain in all people with dementia. However, a common pain assessment process amongst carers involved being able to detect deviation from normal behaviours based upon their intimate knowledge of what is normal for their person. A central hypothesis was thus generated from the data that considered that effective pain assessment for people with dementia is dependent on carers having an intimate knowledge of the individual's normal state of being with dementia. Implications for nursing practice are discussed.
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Affiliation(s)
- D Falls
- St Joseph's Aged Care Facility, Lismore
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Clasen T, Brown J, Suntura O, Collin S. Safe household water treatment and storage using ceramic drip filters: a randomised controlled trial in Bolivia. Water Sci Technol 2004; 50:111-115. [PMID: 15318495] [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] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A randomised controlled field trial was conducted to evaluate the effectiveness of ceramic drip filters to improve the microbiological quality of drinking water in a low-income community in rural Bolivia. In four rounds of water sampling over five months, 100% of the samples were free of thermotolerant (faecal) coliforms (TTC) compared to an arithmetic mean TTC count of 1517, 406, 167 and 245 among control households which continued to use their customary sources of drinking water. The filter systems produced water that consistently met WHO drinking-water standards despite levels of turbidity that presented a challenge to other low-cost POU treatment methods. The filter systems also demonstrated an ability to maintain the high quality of the treated water against subsequent re-contamination in the home.
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Affiliation(s)
- T Clasen
- London School of Hygiene & Tropical Medicine and First Water Ltd, Keppel St, London WC1E 7HT, UK.
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Ehirchiou D, Zorzi W, Biemans R, Vanderbeeke A, Haumont M, Coumans B, Collin S, Jolois O, Bollen A, Heinen E, Antoine N. DNA immunisation. New histochemical and morphometric data. Eur J Histochem 2003; 46:215-22. [PMID: 12472116 DOI: 10.4081/1682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Splenic germinal center reactions were measured during primary response to a plasmidic DNA intramuscular injection. Cardiotoxin-pretreated Balb/c mice were immunized with DNA plasmids encodmg or not the SAG1 protein, a membrane antigen of Toxoplasma gondii. Specific anti-SAG1 antibodies were detected on days 16 and 36 after injection of coding plasmids. The results of ELISAs showed that the SAG1-specific antibodies are of the IgG2a class. Morphometric analyses were done on serial immunostained cryosections of spleen and draining or non-draining lymph nodes. This new approach made it possible to evaluate the chronological changes induced by DNA immunisation in the germinal centres (in number and in size). Significant increases in the number of germinal centres were measured in the spleen and only in draining lymph nodes after plasmid injection, the measured changes of the germinal centers appeared to result from the adjuvant stimulatory effect of the plasmidic DNA since both the coding and the noncoding plasmid DNA induced them. No measurable changes were recorded in the T-dependent zone of lymph organs.
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Affiliation(s)
- D Ehirchiou
- Laboratory of Human Histology, University of Liège, Belgium.
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Abstract
Spermine is a low molecular weight polyamine involved in the postnatal maturation of the gut. When it is administered orally to suckling rats, it induces maturation of the intestinal tract (liver, pancreas and small intestine). Here we show that this polyamine is able to induce precocious intestinal and splenic development in suckling mice. In fact, in 15-day-old mice which had received spermine orally twice daily for 3 days we observed an increase in the ratio of white pulp surface to total spleen surface in comparison with untreated mice. The two macrophage subsets of the marginal zone and the B-cell population were more developed and reached the development level of 5- or 10-week-old mice. The proliferation rate of B-cells was increased by spermine administration to pups. These observations suggest that spermine might play a role in immune system development; further investigation of its effects are intended, namely the evaluation of its capacity to enhance defence during the neonatal period.
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Affiliation(s)
- O Jolois
- Department of Human Histology, University of Liège, Rue de Pitteurs, 20, B-4020 Liège, Belgium.
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Abstract
Over the past few years, polyfunctional thiols present as trace components have been found to play a major role in many food flavors, due to their exceptionally low odor thresholds. Unfortunately, their presence in minute concentration (in ng/kg to a few microg/kg) and their high reactivity make it very difficult to extract and identify them. Furthermore, most of them are not yet commercially available. The aim of this work was to characterize the chromatographic and sensorial properties of 10 synthetic mercaptoketones and mercaptoalcohols. Combinatorial chemistry proved to be a very useful way to synthesize them rapidly. Sulfur-selective sulfur chemiluminescence detection chromatograms coupled with mass spectroscopy enabled the target compounds to be identified. Flavor profiles and best estimate gas chromatography lowest amount detected by sniffing (BE-GC-LOADS) values were further determined by GC-olfactometry. As expected, new, exceptionally odorant molecules (BE-GC-LOADS < 0.1 ng) were revealed by this unusual approach.
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Affiliation(s)
- C Vermeulen
- Unité de Brasserie et des Industries Alimentaires, Faculté d'Ingénierie biologique, agronomique et environnementale, Université Catholique de Louvain, Croix du Sud, 2 bte 7, 1348 Louvain-la-Neuve, Belgium
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Abstract
This paper describes a sensorial aroma extract dilution analysis (AEDA) approach to the analysis of beer aromas derived from hops. To obtain an extract with an odor representative of the original product, the XAD extraction procedure was applied and the experimental conditions were optimized. The aromagrams of three beers were compared: one brewed without hops, one brewed with Saaz hop pellets, and one brewed with Challenger hop pellets. One spicy/hoppy compound, unmodified from hop to beer, proved responsible for the most intense odor in both hopped beer extracts. Another flavoring compound in hops, linalool, also survives through the process to the final beer. Other compounds such as gamma-nonalactone and humuladienone, although not found in our extracts of hop, significantly modify beer aromagrams after hopping. Sulfur compounds characteristic of Challenger hops proved to be at least partially responsible for the unpleasant flavor found in the corresponding beer.
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Affiliation(s)
- G Lermusieau
- Unité de Brasserie et des Industries Alimentaires, Croix du Sud, 2/Bte7, B-1348 Louvain-la-Neuve, Belgium
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Gijs L, Perpète P, Timmermans A, Collin S. 3-methylthiopropionaldehyde as precursor of dimethyl trisulfide in aged beers. J Agric Food Chem 2000; 48:6196-6199. [PMID: 11312791 DOI: 10.1021/jf0007380] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Hop S-methylcysteine sulfoxide has previously been postulated as the precursor of dimethyl trisulfide (DMTS) in beers. The present data point to 3-methylthiopropionaldehyde, the Strecker aldehyde issued from methionine, as another potential precursor in aged beers. Spiking either fresh beer or wort before boiling leads in all cases to higher levels of DMTS after storage. Moreover, special malts with a high level of 3-methylthiopropionaldehyde also favor polysulfide synthesis. A higher pH should increase this onion-like off-flavor, whereas a low pH is unfortunately known to enhance the cardboard flavor of aged beers. 3-methylthiopropanol, issued from yeast reducing activity, can be considered as an additional DMTS source during aging.
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Affiliation(s)
- L Gijs
- Unité de Brasserie et des Industries Alimentaires, Faculté des Sciences Agronomiques, Université catholique de Louvain, Croix du Sud, 2 bte 7, B-1348 Louvain-la-Neuve, Belgium
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Guyot-Declerck C, Chevance F, Lermusieau G, Collin S. Optimized extraction procedure for quantifying norisoprenoids in honey and honey food products. J Agric Food Chem 2000; 48:5850-5855. [PMID: 11141257 DOI: 10.1021/jf000504g] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Norisoprenoids appear as promising compounds for authenticating unifloral honeys. So far, however, no method has been optimized for their isolation from a matrix so rich in sugars. In this framework, an original extraction procedure based on the use of Amberlite XAD-16 was developed. Recovery factors were determined and compared with those obtained with another resin (XAD-2). This was done for different model media and various norisoprenoids. In aqueous or alcoholic solutions, the efficiency of both resins proved very high. As expected, addition of honey decreased the adsorption of nonpolar compounds. This effect was much more pronounced with the lower-porosity XAD-2 support. Sugar addition markedly improved the recovery factors obtained with the XAD-16 resin in the case of more polar norisoprenoids.
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Affiliation(s)
- C Guyot-Declerck
- Université Catholique de Louvain, Unité de Brasserie et des Industries Alimentaires, Place Croix du Sud 2 / Bte 7, B-1348 Louvain-la-Neuve, Belgium
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Collin S, Sirard MA, Dufour M, Bailey JL. Sperm calcium levels and chlortetracycline fluorescence patterns are related to the in vivo fertility of cryopreserved bovine semen. J Androl 2000; 21:938-43. [PMID: 11105921] [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] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Cryopreserved bovine semen is less fertile than fresh semen for reasons that have not been fully elucidated. Cryopreservation is known to disrupt the sperm plasma membrane and it induces premature capacitation of a sperm subpopulation, which may be a result of the increased internal calcium levels after thawing. To test the hypothesis that sperm intracellular calcium level is correlated with in vivo fertility, we used the fluorescent calcium indicator, indo-1, and flow cytometry to assess intracellular calcium levels in frozen-thawed sperm from bulls of varying degrees of fertility. We also tested a second hypothesis that the physiological status of sperm, as assessed by the chlortetracycline (CTC) fluorescent assay, is correlated with fertility. As detected by indo-1 fluorescence, the intracellular calcium level is negatively correlated with bull fertility immediately after thawing (P = .0362; n = 3 ejaculates from each of 10 animals). Moreover, there was a significant difference between the 3 most and least fertile bulls over 4 hours of incubation (P < .05; n = 3 ejaculates per bull). Finally, there was a positive correlation between sperm displaying the CTC acrosome reaction pattern and fertility (P = .0014; n = 3 ejaculates from each of 10 bulls).
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Affiliation(s)
- S Collin
- Centre de Recherche en Biologie de la Reproduction, Département des Sciences Animales, Université Laval, Québec, Québec, Canada
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Abstract
A medium containing labeled leucine-d(10) has been used to show that Saccharomyces cerevisiae was able to produce deuterated 3-methylbutanal in a cold contact fermentation. Whereas residual unreduced Strecker aldehydes bound to polyphenols were considered until now as the main defect of alcohol-free beers, yeast emerges from this work as an additional source of worty flavor. When the same experiment was conducted without leucine, 3-methylbutanal excretion also occurred, indicating that valine could be used by yeast as precursor.
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Affiliation(s)
- P Perpète
- Laboratoire de Brasserie et des Industries Alimentaires, Université Catholique de Louvain, Louvain-la-Neuve, Belgium
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