WorldWideScience

Sample records for nouvelles molecules extractantes

  1. Study of the selectivity of poly-nitrogenous extracting molecules in the complexation of actinides (III) and lanthanides (III) in solution in anhydrous pyridine; Etude de la selectivite de molecules extractantes polyazotees dans la complexation des actinides (III) et des lanthanides (III) en solution dans la pyridine anhydre

    Energy Technology Data Exchange (ETDEWEB)

    Riviere, Ch

    2000-10-05

    The aim of this work is to better understand the factors which contribute to the separation of lanthanides(III) and actinides(III). Polydentate nitrogenous molecules present an interesting selectivity. A thermodynamic study of the complexation in pyridine of lanthanide and uranium by the bipyridine ligand (bipy) has been carried out. The formation constants and the thermodynamic values of the different complexes have been determined. It has been shown that the bipy complexes formation is controlled by the enthalpy and unfavored by the entropy. The conductometry has revealed too a significant difference in the uranium and lanthanides complexation by the bipyridine ligand. The use of the phenanthroline ligand induces a better complexation of the metallic ions but the selectivity is not improved. On the other hand, the decrease of the basicity and the increase of the ligand denticity (for instance in the case of the use of ter-pyridine) favour the selectivity without improving the complexation. The selectivity difference for the complexation of actinides(III) and lanthanides(III) by the different studied ligands (independent systems) has been confirmed by experiments of inter-metals competition. (O.M.)

  2. Separation by liquid-liquid extraction of actinides(III) from lanthanides(III) using new molecules: the picolinamides; Separation par extraction liquide-liquide des actinides(III) des lanthanides(III) par de nouvelles molecules: les picolinamides

    Energy Technology Data Exchange (ETDEWEB)

    Cordier, P Y [CEA Marcoule, Departement de Recherche en Retraitement et en Vitrification, 30 - Bagnols-sur-Ceze (France); [Clermont-Ferrand-2 Univ., 63 - Aubiere (France)

    1996-07-01

    In the field of long-lived radionuclides separation from waste generated during spent fuel reprocessing, the picolinamides have been chosen as potential extractants for the selective extraction of actinides (III) from lanthanides (III). The first studies initiated on the most simple molecule of the picolinamide family, namely 2-pyridinecarboxamide, pointed out that in an aqueous media the complexation stability constant between this ligand and Am(III) is roughly 10 times higher than the ones corresponding to Ln(III). The synthesis of lipophilic derivatives of 2-pyridinecarboxamide leaded to extraction experiments. The extraction of metallic cation by lipophilic picolinamides, according to a solvatation mechanism, is strongly dependent on the nature of the amide function: a primary amide function (group I) leads to a good extraction; on the contrary, there is a decrease for secondary (group II) and tertiary (group III) amide functions. From a theoretical point of view, this work leads finally to the following conclusions: confirmation of the importance of the presence of soft donor atoms within the extractants (nitrogen in our case) for An(III)/Ln(III). Also, sensitivity of this soft donor atom regarding the protonation reaction; prevalence in our case of the affinity of the extractant for the metallic cation over the lipophilia of the extractant to ensure good distribution coefficients. The extraction and Am(III)/Ln(III) separation performances of the picolinamides from pertechnetic media leads to the design of a possible flowsheet for the reprocessing of high level liquid waste, with the new idea of an integrated technetium reflux. (author) 105 refs.

  3. La nouvelle-tableau (2

    Directory of Open Access Journals (Sweden)

    Géraldine Jenvrin

    2012-06-01

    Full Text Available La nouvelle « Frémissante, la feuille se flétrit » met en scène le trouble d'un détenu qui par les seuls objets dont il dispose, lutte pour s'échapper intérieurement. L'usage du regard cinématographique porté sur les détails infimes de la matérialité carcérale, leur exposition sous forme de tableaux se faisant échos, les techniques de l’anonymat et du brouillage des repères objectifs, portent à son comble les dimensions énigmatiques et l'esthétique de la  brièveté propre à la nouvelle tout en permettant de  représenter la résistance de l'homme à l'enfermement et à la persécution.

  4. EDF Energies Nouvelles - 2010 Registration Document

    International Nuclear Information System (INIS)

    2011-01-01

    EDF Energies Nouvelles is a world leader in renewable energy electricity. The company develops, builds and operates clean energy power plants both for its own account and for third parties. Historically, EDF Energies Nouvelles primarily developed its business in two geographical areas, Europe and North America (U.S., Canada and Mexico). EDF Energies Nouvelles is a subsidiary of EDF, helping the Group to achieve its renewable energy goals. The EDF Group generates low-carbon electricity around the world and actively participates in the energy transition. EDF Energies Nouvelles prioritizes development of wind and photovoltaic solar capacity. As an integrated operator with global reach, EDF Energies Nouvelles covers the entire renewable energy chain, from development to operation and maintenance, and manages all project phases in-house. This document is EDF Energies Nouvelles' registration document for the year 2010. It contains information about Group profile, governance, business, investments, property, plant and equipment, management, financial position, employees, shareholders, etc. The document includes the half-year and full year financial reports

  5. EDF Energies Nouvelles. Financial report at June 30, 2011

    International Nuclear Information System (INIS)

    2011-01-01

    EDF Energies Nouvelles is a world leader in renewable energy electricity. The company develops, builds and operates clean energy power plants both for its own account and for third parties. Historically, EDF Energies Nouvelles primarily developed its business in two geographical areas, Europe and North America (U.S., Canada and Mexico). EDF Energies Nouvelles is a subsidiary of EDF, helping the Group to achieve its renewable energy goals. The EDF Group generates low-carbon electricity around the world and actively participates in the energy transition. EDF Energies Nouvelles prioritizes development of wind and photovoltaic solar capacity. As an integrated operator with global reach, EDF Energies Nouvelles covers the entire renewable energy chain, from development to operation and maintenance, and manages all project phases in-house. This document is EDF Energies Nouvelles's half-year financial report for 2011. It contains a half-year activity report, the consolidated financial statements at June 30, 2011 and the report drafted by the Statutory Auditors

  6. EDF Energies Nouvelles. Consolidated financial statements at 30 June 2009

    International Nuclear Information System (INIS)

    2010-01-01

    EDF Energies Nouvelles is a world leader in renewable energy electricity. The company develops, builds and operates clean energy power plants both for its own account and for third parties. Historically, EDF Energies Nouvelles primarily developed its business in two geographical areas, Europe and North America (U.S., Canada and Mexico). EDF Energies Nouvelles is a subsidiary of EDF, helping the Group to achieve its renewable energy goals. The EDF Group generates low-carbon electricity around the world and actively participates in the energy transition. EDF Energies Nouvelles prioritizes development of wind and photovoltaic solar capacity. As an integrated operator with global reach, EDF Energies Nouvelles covers the entire renewable energy chain, from development to operation and maintenance, and manages all project phases in-house. This document is EDF Energies Nouvelles's registration document for the year 2009. It contains information about Group profile, governance, business, investments, property, plant and equipment, management, financial position, employees, shareholders, etc. The document includes the group's consolidated financial statements at 31 December 2008

  7. La nouvelle vague in polarized neutron scattering

    International Nuclear Information System (INIS)

    Mezei, F.

    1986-01-01

    Polarized neutron research, like many other subjects in neutron scattering developed in the footsteps of Cliff Shull. The classical polarized neutron technique he pioneered was generalized around 1970 to vectorial beam polarizations and this opened up the way to a ''nouvelle vague'' of neutron scattering experiments. In this paper I will first reexamine the old controversy on the question whether the nature of the neutron magnetic moment is that of a microscopic dipole or of an Amperian current loop. The problem is not only of historical interest, but also of relevance to modern applications. This will be followed by a review of the fundamentals on spin coherence effects in neutron beams and scattering, which are the basis of vectorial beam polarization work. As an example of practical importance, paramagnetic scattering will be discussed. The paper concludes with some examples of applications of the vector polarization techniques, such as study of ferromagnetic domains by neutron beam depolarization and Neutron Spin Echo high resolution inelastic spectroscopy. The sample results presented demonstrate the new opportunities this novel approach opened up in neutrons scattering research. (orig.)

  8. Nouvelles et activités | Page 6 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Consultez les nouvelles et les activités. Utilisez cet outil de recherche pour trouver des nouvelles ou des activités précis dans le site Web du CRDI. Content type. Tout. Activités. Avis aux médias. Bulletins. Communiqués. Nouvelle ...

  9. Nouvelles et activités | Page 2 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Consultez les nouvelles et les activités. Utilisez cet outil de recherche pour trouver des nouvelles ou des activités précis dans le site Web du CRDI. Content type. Tout. Activités. Avis aux médias. Bulletins. Communiqués. Nouvelle ...

  10. Nouvelles et activités | Page 7 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Consultez les nouvelles et les activités. Utilisez cet outil de recherche pour trouver des nouvelles ou des activités précis dans le site Web du CRDI. Content type. Tout. Activités. Avis aux médias. Bulletins. Communiqués. Nouvelle ...

  11. Nouvelles et activités | Page 5 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Consultez les nouvelles et les activités. Utilisez cet outil de recherche pour trouver des nouvelles ou des activités précis dans le site Web du CRDI. Content type. Tout. Activités. Avis aux médias. Bulletins. Communiqués. Nouvelle ...

  12. Access. Challenge for Change/Societe Nouvelle Number Twelve.

    Science.gov (United States)

    Prinn, Elizabeth, Ed.; Henaut, Dorothy Todd, Ed.

    This issue of Access, the journal issued periodically by Challenge for Change/Societe Nouvelle, contains two groups of articles. The first focuses upon the Skyriver Project, relating how a project was developed which used film and video tape as a means of helping Alaskan communities to assess their own needs and to advocate for themselves the…

  13. Access. Challenge for Change/Societe Nouvelle Number Eleven.

    Science.gov (United States)

    Prinn, Elizabeth, Ed.

    Access is a journal published three or four times a year by Challenge for Change/Societe Nouvelle (CCSN). CCSN is an experimental program established by the Government of Canada as a cooperative effort between the National Film Board of Canada and certain of the Government's departments. Its purposes are to improve communications, create greater…

  14. Jean Gadrey, Nouvelle économie, nouveau mythe ?

    Directory of Open Access Journals (Sweden)

    Diane-Gabrielle Tremblay

    2002-10-01

    Full Text Available La « nouvelle économie » est partout dans les médias nord-américains, comme européens. L’ouvrage de Jean Gadrey est rafraîchissant, car il présente une critique et une analyse minutieuse du concept, de son apparition, des développements qui y sont associés, des thèses et idées défendues au nom de la « nouvelle économie ».Comme il le note bien « les mythes mobilisateurs fleurissent, mais la réflexion sur les contours de cet âge et sur les risques sociaux à prévenir est inexistante : les formul...

  15. La hernie ombilicale africaine : nouvelle classification et revue de 30 ...

    African Journals Online (AJOL)

    L'objectif de ce travail était de proposer une nouvelle classification de la hernie ombilicale de l'enfant africain et d'évaluer les résultats du traitement chirurgical.Il s'agit d'une étude prospective portant sur 30 patients porteurs de hernie ombilicale, qui s'est déroulée sur une période de un an et demi dans les services de ...

  16. Nouvelle espèce des Syntomides (Lepidoptera Heterocera)

    NARCIS (Netherlands)

    Snellen, P.C.T.

    1886-01-01

    Quatre mâles frais et bien conservés de 58—64 millim. d’envergure. Cette nouvelle espèce, gigantesque pour une Syntomide, appartient au genre Automolis, tel qu’il a été défini par Herrich-Schäffer, dans son ouvrage »Sammlung aussereuropäischer Schmetterlinge” (p. 21); le nom est emprunté au bien

  17. La viticulture bio, une nouvelle modernité

    OpenAIRE

    Raphaël Schirmer

    2004-01-01

    Les difficultés d'expansion de la viticulture biologique en France proviennent avant tout de la rupture conséquente qu'elle introduit en ce qui concerne notre rapport à l'espace. La place de l'agriculteur dans la société est refondée, les paysages tels que nous les entendions sont bouleversés. Il semble bien qu'une nouvelle modernité soit en train de se développer, à côté de tant d'autres il est vrai.

  18. LHC 2008 lectures "Une nouvelle vision du monde"

    CERN Multimedia

    2008-01-01

    The history of the science of the Universe and the science of matter have been marked by a small number of "revolutions" that have turned our understanding of the infinitesimally large and the infinitesimally small on its head. New ways of looking at the world have come about sometimes through conceptual advances and sometimes through innovations in scientific instrumentation. How do things stand at the beginning of the 21st century? Will today’s large-scale machine projects like the LHC and gravitational wave detectors pave the way for a new scientific revolution? Thursday, 15 May 2008 at 8.00 p.m. Une nouvelle vision du monde Jean-Pierre Luminet, Research Director at the CNRS The Globe, first floor No specialist knowledge required. Entrance free. To reserve call + 41 (0) 22 767 76 76 http://www.cern.ch/globe

  19. NOUVELLES PERSPECTIVES EN ONCOLOGIE MEDICALE MEDECINE MOLECULAIRE ET SES PERSPECTIVES

    Directory of Open Access Journals (Sweden)

    Jean-Yves BLAY

    2017-05-01

    Full Text Available La médecine  moléculaire du cancer  s’appuie sur l’identification d’anomalies génomique de  l’ADN des cellules tumorales, permettant de guider le traitement des patients, en choisissant des inhibiteurs agissant sur les protéines mutées codées par les gènes mutés. Cependant, on assiste depuis 10 ans à l’émergence très rapide d’un nouveau corpus de connaissance décrivant les anomalies génomiques des cellules cancéreuses au sein des programmes internationaux  comme ICGC ou TCGA, permettant de déboucher sur de nouvelles classifications nosologiques mais démontrant aussi l’extrème  complexité et variabilité clonale des cellules cancéreuses  chez le patient humain. Il s’agit désormais d’utiliser ces données  nouvelles de manière  efficace. Ceci requiert la constitution de plateformes de diagnostic  explorant progressivement avec  une plus grande profondeur  les anomalies moléculaire de chaque patient individuel, et l’organisation de réunions de concertation pluridisciplinaires moléculaire permettant d’intégrer ces données au contexte  clinique et global du patient, et requérant la  contribution  croissante des bio-informaticiens. Ce  court article  fait le point  sur l’évolution de cette médecine moléculaire.

  20. EDF Energies Nouvelles. Consolidated financial statements at 31 December 2008 Prepared in accordance with IFRSs

    International Nuclear Information System (INIS)

    2009-01-01

    EDF Energies Nouvelles is a world leader in renewable energy electricity. The company develops, builds and operates clean energy power plants both for its own account and for third parties. Historically, EDF Energies Nouvelles primarily developed its business in two geographical areas, Europe and North America (U.S., Canada and Mexico). EDF Energies Nouvelles is a subsidiary of EDF, helping the Group to achieve its renewable energy goals. The EDF Group generates low-carbon electricity around the world and actively participates in the energy transition. EDF Energies Nouvelles prioritizes development of wind and photovoltaic solar capacity. As an integrated operator with global reach, EDF Energies Nouvelles covers the entire renewable energy chain, from development to operation and maintenance, and manages all project phases in-house. This document is EDF Energies Nouvelles's registration document for the year 2008. It contains information about Group profile, governance, business, investments, property, plant and equipment, management, financial position, employees, shareholders, etc. The document includes the group's consolidated financial statements at 31 December 2008

  1. EDF Energies Nouvelles. Consolidated financial statements at 31 December 2007 Prepared in accordance with IFRSs

    International Nuclear Information System (INIS)

    2008-01-01

    EDF Energies Nouvelles is a world leader in renewable energy electricity. The company develops, builds and operates clean energy power plants both for its own account and for third parties. Historically, EDF Energies Nouvelles primarily developed its business in two geographical areas, Europe and North America (U.S., Canada and Mexico). EDF Energies Nouvelles is a subsidiary of EDF, helping the Group to achieve its renewable energy goals. The EDF Group generates low-carbon electricity around the world and actively participates in the energy transition. EDF Energies Nouvelles prioritizes development of wind and photovoltaic solar capacity. As an integrated operator with global reach, EDF Energies Nouvelles covers the entire renewable energy chain, from development to operation and maintenance, and manages all project phases in-house. This document is EDF Energies Nouvelles's registration document for the year 2007. It contains information about Group profile, governance, business, investments, property, plant and equipment, management, financial position, employees, shareholders, etc. The document includes the group's consolidated financial statements at 31 December 2007

  2. EDF Energies Nouvelles. Consolidated financial statements at 31 December 2006 Prepared in accordance with IFRSs

    International Nuclear Information System (INIS)

    2007-01-01

    EDF Energies Nouvelles is a world leader in renewable energy electricity. The company develops, builds and operates clean energy power plants both for its own account and for third parties. Historically, EDF Energies Nouvelles primarily developed its business in two geographical areas, Europe and North America (U.S., Canada and Mexico). EDF Energies Nouvelles is a subsidiary of EDF, helping the Group to achieve its renewable energy goals. The EDF Group generates low-carbon electricity around the world and actively participates in the energy transition. EDF Energies Nouvelles prioritizes development of wind and photovoltaic solar capacity. As an integrated operator with global reach, EDF Energies Nouvelles covers the entire renewable energy chain, from development to operation and maintenance, and manages all project phases in-house. This document is EDF Energies Nouvelles's registration document for the year 2006. It contains information about Group profile, governance, business, investments, property, plant and equipment, management, financial position, employees, shareholders, etc. The document includes the group's Consolidated financial statements at 31 December 2006

  3. Nouvelles et activités | Page 6 | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Jean Lebel, président du CRDI, et Andrew Campbell, premier dirigeant de l'. CRDI. NOUVELLES ACTIVITÉS. Le CDRI renouvelle son partenariat avec ACIAR en matière de sécurité alimentaire. Le CRDI et le Australian Centre for International Agricultural Research, ont conclu un accord en... Vous voulez en savoir plus Le ...

  4. Synthèse, étude toxicologique et activité psychotrope de nouvelles ...

    African Journals Online (AJOL)

    Hilaire

    Pharmacology. Synthèse, étude toxicologique et activité psychotrope de nouvelles arylidènpyridazin-. 3-ones N-substituées. Adnane BENMOUSSA1*, Pascal Manuele KANYONGA2,3, M'Hammed ANSAR1, Amina ZELLOU2, J EL. HARTI1, Jamal LAMSAOURI1, My Abbes FAOUZI2 , Ahmed ZAHIDI1, Hamid BENZIANE1, ...

  5. Une nouvelle vision pour AfricaAdapt – Entrevue avec Moussa Na ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    24 févr. 2011 ... Réseau panafricain lancé en mai 2009, AfricaAdapt vient de recevoir le feu vert pour l'exécution d'une nouvelle phase d'activités de deux ans, qu'appuie le programme Adaptation aux changements climatiques en Afrique.

  6. Performances d'une nouvelle approche dans l'estimation au champ

    African Journals Online (AJOL)

    ACSS

    Elle possède cependant des limitations, dues à l'organisation temporaire d'une .... Performances d'une nouvelle approche dans l'estimation au champ utilisant le principe de la ... différents types de résidus (soja, luzerne, haricot et maïs) et ...

  7. Régler les conflits locaux en Amérique latine : de nouvelles ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Au cours de la dernière décennie, les conflits locaux se sont répandus dans toute ... conjuguées à de nouvelles façons de concevoir la nature des conflits locaux. ... En partenariat avec l'Organization for Women in Science for the Developing ...

  8. IFP Energies Nouvelles. 2014 Activity report - Innovating for energy

    International Nuclear Information System (INIS)

    2015-01-01

    As part of the public-interest mission with which it has been tasked by the public authorities, IFP Energies Nouvelles (IFPEN) focuses on: - providing solutions to take up the challenges facing society in terms of energy and the climate, promoting the emergence of a sustainable energy mix, - creating wealth and jobs by supporting French and European economic activity, and the competitiveness of related industrial sectors. Despite the current economic environment, 2014 was a good year for IFPEN. In the field of renewable energies, major milestones were reached in two significant projects dedicated to the production of second generation biofuels in which IFPEN is very actively involved: processes developed in Futurol TM are already in the pre-marketing phase, while the construction of the two pilot units for the BioTfueL project has just been launched. In the field of ocean energies, IFPEN research has led to the first partnership agreements relating to floating wind turbines anchor technologies and command control systems for wind energy and wave energy conversion. In the transport sector, game-changing concepts are beginning to emerge, such as smart battery charging and a Rankine cycle system for an internal combustion engine transforming combustion heat into energy. In addition, IFPEN have joined forces with innovative SMEs to boost their research in the fields of electric power-trains and power electronics. Finally, IFPEN launched an eco-driving application that has proved extremely popular with the public. Turning now to oil and gas, IFPEN continued to expand its range of basin and reservoir simulation, modeling and characterization software, and it signed several contracts in the field of chemical enhanced recovery solutions with its EOR (Enhanced Oil Recovery) Alliance TM partners. IFPEN also developed new generations of high-performance catalysts and improved the conversion rate of its processes to enable refiners to convert increasingly heavy crudes and

  9. IFP Energies nouvelles. 2016 Activity Report - Innovating for energy

    International Nuclear Information System (INIS)

    2017-01-01

    IFP Energies Nouvelles is a major research and training player in the fields of energy, transport and the environment. From research to industry, technological innovation is central to all its activities, structured around three strategic priorities: sustainable mobility, new energies and responsible oil and gas. As part of the public-interest mission with which it has been tasked by the public authorities, IFPEN focuses on: - providing solutions to take up the challenges facing society in terms of energy and the climate, promoting the transition towards sustainable mobility and the emergence of a more diversified energy mix; - creating wealth and jobs by supporting French and European economic activity, and the competitiveness of related industrial sectors. An integral part of IFPEN, its graduate engineering school - IFP School - prepares future generations to take up these challenges. IFPEN has proven expertise across the entire value chain, from fundamental research to innovation. It is funded both by a state budget and by its own resources provided by industrial partners. The latter account for over 50% of IFPEN's total budget, a configuration that is quasi unique in France. The aim of IFPEN's R and I programs is to overcome existing scientific and technological challenges in order to develop innovations that can be used by industry. IFPEN's fundamental research program aims to create a bedrock of knowledge essential for the development of innovations. The scientific expertise of IFPEN's researchers is internationally recognized and they are regularly consulted by the public authorities to provide their insight in their specific fields to inform the decision-making process. IFPEN's economic model is based on the transfer to industry of the technologies developed by its researchers. This technology transfer to industry generates jobs and business, fostering the economic development of fields and approaches related to the mobility, energy and eco-industry sectors

  10. Molecule nanoweaver

    Science.gov (United States)

    Gerald, II; Rex, E [Brookfield, IL; Klingler, Robert J [Glenview, IL; Rathke, Jerome W [Homer Glen, IL; Diaz, Rocio [Chicago, IL; Vukovic, Lela [Westchester, IL

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  11. Toxoplasmose : une nouvelle approche vaccinale à base de nanoparticules d’amidon donne des résultats prometteurs

    OpenAIRE

    Le Rouzic, Jacques

    2015-01-01

    Pour lutter contre la toxoplasmose chez les ovins, des chercheurs de l’INRA, de l’Université de Tours et de la Faculté de Médecine de Lille ont développé une nouvelle approche vaccinale, utilisant des nanoparticules d’amidon et une administration par voie muqueuse. Cette approche ouvre de nouvelles perspectives vers des vaccins plus sûrs et plus efficaces.

  12. L’Observatoire numérique Nouvelle-Calédonie

    Directory of Open Access Journals (Sweden)

    Charlotte Ullmann

    2013-06-01

    Full Text Available Ses missions consistent à observer le développement numérique et favoriser l’animation territoriale des acteurs en Nouvelle-Calédonie. Parrainée par l’association calédonienne pour les technologies de l’information et de la communication (ACTIC et le ministère en charge de l’économie numérique du Gouvernement de Nouvelle-Calédonie nommé depuis mai 2009, une mission d’étude a été menée depuis juin 2010 pour définir les contours d’un Observatoire numérique. A travers cette étude, il s’agissai...

  13. Description d’une espèce nouvelle du genre Ectatorhinus (Coleoptera: fam. Curculionidae)

    NARCIS (Netherlands)

    Roelofs, W.

    1890-01-01

    Monsieur Neervoort van de Poll ayant reçu récemment avec d’autres insectes une nouvelle espèce d’ Ectatorhinus, capturée dans l’intérieur de Bedagei (Deli, Sumatra orient.) par M. J. Z. Kannegieter, m’a invité de la décrire, ce que je fais avec d’autant plus de plaisir que j’avais décrit dans le

  14. Une Cyathura cavernicole nouvelle de Sarawak – Kalimantan du Nord (Isopoda, Anthuridae)

    NARCIS (Netherlands)

    Andreev, Stoitze

    1982-01-01

    A l’occasion d’une expédition spéléologique effectuée en 1978 à Sarawak et organisée par la Royal Geographical Society, le biospéléologue anglais Dr. Ph. Chapman a recueilli quelques exemplaires d’un Isopode des eaux douces souterraines, appartenant à une nouvelle espèce du genre Cyathura. La

  15. Nouvelles et activités | CRDI - Centre de recherches pour le ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Restez informé. Soyez au courant des toutes dernières nouvelles au sujet des programmes et des activités du CRDI, de ses réalisations et de celles des chercheurs que nous subventionnons. Apprenez-en plus sur les événements à venir au Canada et dans nos régions ou obtenez des renseignements sur les conférences, ...

  16. Une nouvelle vision de la transition en Syrie | CRDI - Centre de ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Une nouvelle vision de la transition en Syrie. 07 juin 2016. Bénéficiaire : Syrian Center for Political and Strategic Studies (SCPSS) Période visée : de juillet 2012 à août 2013. État : en cours de clôture. Financement accordé : 441 000 CAD. La Coalition nationale syrienne a officiellement donné son aval à une feuille de route ...

  17. Nouvelles de l'Italie sur la linguistique et l'education

    Directory of Open Access Journals (Sweden)

    Raffaele Simone

    1984-12-01

    Full Text Available L'auteur donne. des informations sur l'état actuel des débats concernant le développement du langage dans l'école italienne d'aujourd'hui, et prop6se U:ne "nouvelle" notion de linguistique appliquée, considérée en tant que confrontation de systèmes de sens, plutôt de systèmes de formes.

  18. DESIGNOR: une méthode nouvelle d'aide à la conception des produits industriels

    OpenAIRE

    Choffray, Jean-Marie

    1980-01-01

    Cet article présente une méthode nouvelle, appelée DESIGNOR, d'aide à la décision marketing. Son objectif est d'accroître la créativité au cours du processus de développement d'un nouveau produit industriel et de réduire les risques d'échec commercial.

  19. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 4. Molecule Matters – van der Waals Molecules - History and Some Perspectives on Intermolecular Forces. E Arunan. Feature Article Volume 14 Issue 4 April 2009 pp 346-356 ...

  20. Atkins' molecules

    CERN Document Server

    Atkins, Peters

    2003-01-01

    Originally published in 2003, this is the second edition of a title that was called 'the most beautiful chemistry book ever written'. In it, we see the molecules responsible for the experiences of our everyday life - including fabrics, drugs, plastics, explosives, detergents, fragrances, tastes, and sex. With engaging prose Peter Atkins gives a non-technical account of an incredible range of aspects of the world around us, showing unexpected connections, and giving an insight into how this amazing world can be understood in terms of the atoms and molecules from which it is built. The second edition includes dozens of extra molecules, graphical presentation, and an even more accessible and enthralling account of the molecules themselves.

  1. Interstellar Molecules

    Science.gov (United States)

    Solomon, Philip M.

    1973-01-01

    Radioastronomy reveals that clouds between the stars, once believed to consist of simple atoms, contain molecules as complex as seven atoms and may be the most massive objects in our Galaxy. (Author/DF)

  2. Adhesion molecules

    CERN Document Server

    Preedy, Victor R

    2016-01-01

    This book covers the structure and classification of adhesion molecules in relation to signaling pathways and gene expression. It discusses immunohistochemical localization, neutrophil migration, and junctional, functional, and inflammatory adhesion molecules in pathologies such as leukocyte decompression sickness and ischemia reperfusion injury. Highlighting the medical applications of current research, chapters cover diabetes, obesity, and metabolic syndrome; hypoxia; kidney disease; smoking, atrial fibrillation, and heart disease, the brain and dementia; and tumor proliferation. Finally, it looks at molecular imaging and bioinformatics, high-throughput technologies, and chemotherapy.

  3. LE SENTIMENT DE LA NATURE DANS LA NOUVELLE HELOISE DE ROUSSEAU

    OpenAIRE

    YÖNTEN, Yrd.Doç.Dr.Uğur

    2002-01-01

    Yrd.Doç.Dr.Uğur YÖNTEN D.Ü.Eğitim Fakültesi Fransız Dili Eğitimi A.B.D Bu çalışmamızda Jean-Jacques Rousseau'nun Julie ou La Nouvelle Héloïse (Julie Ya da Yeni Héloïse) adlı romanında "doğa tutkusunu" incelemeye çalıştık. Romandaki doğa yansımalarını ele almadan önce yazardaki bu duygunun nasıl ve ne zam...

  4. La nouvelle bourgeoisie islamique. Le modèle turc, de Dilek Yankaya

    OpenAIRE

    Lelandais, Gülçin Erdi

    2016-01-01

    De nombreux travaux sur la Turquie contemporaine ont été réalisés ces dernières années en France. La plus grande partie d’entre eux se focalise sur le champ politique et ses évolutions, les minorités ethniques — notamment les Kurdes –, et sur des mobilisations sociales, politiques et environnementales comme la mobilisation autour du parc Gezi. Le livre de Dilek Yankaya ouvre un nouveau champ d’analyse avec sa recherche, pionnière en son genre en France, qui étudie l’émergence d’une nouvelle é...

  5. Le méga-fichier TES dans une nouvelle architecture de surveillance

    OpenAIRE

    Vitalis, André

    2017-01-01

    La récente création du méga-fichier biométrique TES de tous les Français, répond, même s’il n’est pas mis en avant, à un souci sécuritaire. Si l’on veut véritablement comprendre les raisons et la portée de cette création, il faut la replacer dans la nouvelle architecture de surveillance en cours de construction depuis plus d’une décennie.

  6. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Molecule Matters - Dinitrogen. A G Samuelson J Jabadurai. Volume 16 Issue 12 ... Author Affiliations. A G Samuelson1 J Jabadurai1. Department of Inroganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India.

  7. Molecule Matters

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 9. Molecule Matters - A Chromium Compound with a Quintuple Bond. K C Kumara Swamy. Feature Article Volume 11 Issue 9 September 2006 pp 72-75. Fulltext. Click here to view fulltext PDF. Permanent link:

  8. Living on the mall : patterning and place making in the case study of Nouvelle

    Energy Technology Data Exchange (ETDEWEB)

    Gillies-Smith, S.; Ring, H. [Martha Schwartz, Inc., Cambridge, MA (United States)

    2007-07-01

    One of the largest habitable green roofs in the New England area was designed by Martha Schwartz Inc. The green roof spans 1.5 acres of mall rooftop that will be accessible by two connected condominium towers. A condominium complex associated with the expansion of the Natick Mall entitled Nouvelle, offers a new type of housing, in which a private, residential apartment complex adjoins a suburban, upscale indoor shopping mall. There are many new opportunities to use the expansive area of the mall complex roof to function as a productive, multi-use, shared private park. As an art-based landscape architectural practice, the office has adapted bold and graphic qualities as a model for its green roof design. The Nouvelle green roof offers dynamic circulation, enjoyable social space and recreation, intersecting a continuous coverage of patterned sedum and river stone that spans an entire roofscape. The green roof demonstrates an innovative combination of intensive and extensive plantings that create a system of legible and visually pleasing patterning from above. This case study addressed these innovations and implementation challenges within the context of mall architecture and green roof technologies. In addition, it also identified the social uses of roof spaces, and the aesthetics and sustainability of patterning in intensive and extensive planting design.

  9. The Function of the Medieval in Jean-Jacques Rousseau's Nouvelle Heloise : A Rereading of the Abelard and Heloise Motif

    NARCIS (Netherlands)

    Montoya, Alicia C.

    2010-01-01

    Jean-Jacques Rousseau's critical rewriting in his Nouvelle H,lo

  10. Nouvelle cuisine

    CERN Document Server

    2007-01-01

    Diners at CERN's Restaurant No. 1 have been adjusting to some temporary arrangements while building work takes place in the main service area. The essential renovation will bring many improvements in the near future. The restaurant before restoration. A huge white marquee erected on a green lawn greets the eye. The sight is familiar in the summer months, but the sharp chill in the air disrupts the scene. Instead of a mid-summer's day, it's actually the middle of January. This apparently strange reversal of seasons is a way of providing an additional dining and service area outside Restaurant No. 1. As renovations get underway inside, the mysterious hum of drills and the hollow echo of hammering behind scaffold boards raise our curiosity about what is in-store. 'Everything will be better,' says Mario Zanolini, head waiter of Restaurant No. 1. 'It will be more comfortable for the customers. The free-flow area will be bigger and there will be 7 tills instead of the previous 5.' These are just for starters. ...

  11. Une Nouvelle Orientation Psychophysique dans la Pédagogie Théâtrale Contemporaine

    Directory of Open Access Journals (Sweden)

    Vezio Ruggieri

    2015-09-01

    Full Text Available Cet article a pour but de présenter comment les apports du modèle psychophysiologique bio-existentialiste élaboré par Vezio Ruggieri et ses collaborateurs peuvent jeter une lumière nouvelle sur les processus sous-jacents le jeu de l’acteur tels que la présence scénique, le processus d’identification avec un personnage et le complexe mécanisme de la prosodie. Cet encadrement théorique, qui voit le rapport corps-esprit dans une relation circulaire, éclairera le lecteur sur les bases physiologiques de la perception et de l’imagination ainsi que sur le rôle fondamental que la structure musculaire joue dans la construction de ces phénomènes.

  12. Securite, dangerosite, biopolitique: trois versants d'une nouvelle pratique de pouvoir sur les individus

    Directory of Open Access Journals (Sweden)

    Jean-François Bert

    2012-01-01

    Full Text Available Le questionnement de Foucault sur la judiciarisation des sociétés contemporaines renvoie à plusieurs controverses qui, entre 1974 et 1976, ont spécifiquement concerné la question du vivant comme de son rapport au champ du droit et des institutions politiques. Ces polémiques se sont cristallisées autour d'affaires judiciaires retentissantes mais également autour d'un discours technique et politique qui donne une place nouvelle aux notions de dangerosité, de sécurité et à la question plus générale de la gestion du vivant. Trois discours qui, pour Foucault, sont révélateur d'un profond changement de société et de mode de gouvernement des individus.

  13. Qui sera le nouvel Einstein ? Vers une nouvelle theorie de la gravitation

    Science.gov (United States)

    Bonnet-Bidaud, J. M.

    1999-10-01

    Un debat de plus d'un siecle a resurgi ces toutes dernieres annees avec une vigueur nouvelle. L'enjeu ? Mettre fin, ni plus ni moins, a l'une des contradictions les plus inouies de la physique fondamentale, en reconciliant mecanique quantique et relativite generale. En effet, a l'heure ou la gravitation semble enfin sur le point de fusionner avec les trois autres forces de la nature. il est certain que la relativite d'Einstein doit etre bientot remplacer par une autre theorie... Reste quye tous les physiciens sont loin de s'accorder sur la marche a suivree. Gravitation quantique, relativite d'echelle, supersymetrie, les candidates ne manquent pas.

  14. La « nouvelle modernité » urbaine.

    Directory of Open Access Journals (Sweden)

    Alexis Salanson

    2003-01-01

    Full Text Available Président du conseil scientifique de l'Institut « Pour la ville en mouvement » et professeur à l'Institut français d'urbanisme (Paris 8, François Ascher résume dans cet ouvrage les thèses qu'il a défendues tout au long de ses précédentes publications 1  : la société dans laquelle nous vivons s'éloigne irrémédiablement de ce qu'elle fut pendant la révolution industrielle pour basculer dans une « nouvelle modernité ». Celle-ci conduit à repenser ...

  15. Karl Polanyi, la Nouvelle sociologie économique et les forces du marché

    Directory of Open Access Journals (Sweden)

    Ronan Le Velly

    2008-12-01

    Full Text Available Cet article montre en quoi plusieurs auteurs de la Nouvelle sociologie économique tendent à adopter un regard incomplet sur les forces du marché. Pour cela, l’auteur distingue deux notions d’encastrement renvoyant pour la première à un cadre méthodologique institutionnaliste et pour la seconde à l’observation du poids variable des forces du marché. Il établit qu’autant des sociologues classiques comme Weber ou Polanyi ont su coupler ces deux approches, autant plusieurs travaux majeurs de la Nouvelle sociologie économique, notamment ceux de Zelizer, de Fligstein et de Biggart, adoptent la première perspective mais ne traitent que de façon partielle de la seconde. L’auteur met particulièrement en cause les objets de recherche retenus par ces derniers auteurs, dès lors que sont systématiquement privilégiées des situations où les forces du marché sont tenues à l’écart.This article shows how many authors of the New Economic Sociology tend to adopt an incomplete view of market forces. The author distinguishes two notions of embeddedness, one related to the institutionalist theories and the second to the observation of the variable weight of market forces. It is established that classical sociologists such as Weber or Polanyi have joined these two approaches, while manyu works of the New sociological economy, for examle those of Zelizer, Fligstein or Biggart adopt the first perspective, but only treat the second partially. The author particularly questions the research objects chosen by these authors, since he considers that they generally refer to situations where market forces are held at bay.

  16. La nouvelle donne de la santé globale : dynamiques et écueils

    Directory of Open Access Journals (Sweden)

    Marine Buissonnière

    2012-04-01

    Full Text Available Les quinze dernières années ont été marquées par l’avènement de nouveaux acteurs dans le champ de la santé globale et l’augmentation de l’aide au développement en faveur de la santé. Ces acteurs ont capté une partie importante des ressources privées et publiques supplémentaires disponibles et se sont imposés comme les pièces maîtresses de ce nouvel échiquier, aux dépens des institutions traditionnelles qui ont graduellement perdu leur prépondérance et ont vu leur leadership s’affaiblir. Les choix et politiques de santé ont peu à peu échappé à la seule autorité des institutions qui en avaient jusqu’alors le mandat et en assumaient la charge. Certains pans entiers de la santé sont désormais dominés par des financeurs privés, devenus de facto prescripteurs d’orientations de santé publique. Cette nouvelle donne pose des questions essentielles de gouvernance et de responsabilité. Qui décide des orientations ? Comment les décisions sont-elles prises ? Les pays destinataires de l’aide doivent encore trop souvent subir le manque de coordination des donateurs et l’absence d’alignement des agendas. Dans ce contexte, et en prenant acte de cette nouvelle réalité, quelques pistes mériteraient d’être explorées afin de garantir que les orientations en matière de santé globale reflètent au mieux la réalité des besoins et les aspirations des pays.

  17. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 14; Issue 12. Molecule Matters van der Waals Molecules - Noble Gas Clusters are London Molecules! E Arunan. Feature Article Volume 14 Issue 12 December 2009 pp 1210-1222 ...

  18. Discours rationnel vs discours passionnel. Analyse sémiotique d’un fragment de la Nouvelle Héloïse

    Directory of Open Access Journals (Sweden)

    Alexandrina Mustăţea

    2007-05-01

    Full Text Available Roman sentimental, La Nouvelle Héloïse double son parcours narratif d’un parcours émotionnel et sensoriel qui dessine ce que l’on pourrait nommer la configuration passionnelle de l’ensemble textuel. Roman épistolaire, La Nouvelle Héloïse situe le foyer de la passion dans le corps même du scripteur de la lettre, à la fois être du monde sensible et instance discursive.

  19. Energy and greenhouse gas profile of the Nouvelle Aquitaine region. Release 2017

    International Nuclear Information System (INIS)

    Rousset, Alain; Poitevin, Lionel; Loeb, Amandine; Philippot, Herve; Rebouillat, Lea; Jacquelin, Antoine

    2017-06-01

    This publication first proposes graphs and comments characterising final energy consumption of the Nouvelle Aquitaine region: regional situation in 2015 (analysis per sector and per energy), primary resources, social-economic analysis (energy bill, level of energy poverty, burden due to old housing and commuting for households), evolution of energy consumption between 2005 and 2015 (per sector, per source of energy, evolution of energy intensity and of the energy bill). The next part addresses greenhouse gas emissions: regional situation in 2015 (distribution in terms of emission type and per gas), evolutions between 1990 and 2015, evolutions per sector. The third part addresses renewable energies: regional situation for the different types of renewable energy, comparison with final energy consumption, comparison with national data, production evolutions, focus per sector (wood and wood by-products, heat pumps in the housing sector, urban waste valorisation units, biogas valorisation, bio-fuels, wind energy, hydroelectricity, solar photovoltaic). The last part recalls national objectives related to energy, to greenhouse gas emissions for France and for the region, in relationship with the law on energy transition and for a green growth

  20. Nouvelle application de control des cavités 200 MHz RF du PS (CERN)

    CERN Document Server

    Cotte, D

    2011-01-01

    Le système Radio Fréquence (RF) 200MHz du PS est un outil essentiel pour la préparation des faisceaux haute intensité du PS. Dans l’anneau PS on trouve 6 cavités 200 MHz utilisées pour contrôler : • l’émittance longitudinale des « bunches » • le processus de « Rebunching » du faisceau avant de l’envoyer au SPS. Chaque cavité est pilotée par des événements appelés « timing » et suit une fonction de tension programmée. Cependant, l’électronique utilisée pour piloter les cavités 200 MHz du PS est obsolète et sa fiabilité non garantie pour cause du manque de pièces de rechange. Ce document décrit le fonctionnement du nouveau programme d’application qui fait abstraction de l’ancienne matrice hardware. Elle suit les recommandations décrites dans l’étude d’une nouvelle structure pour le système RF 200MHz du PS. [1

  1. SEMINAIRE DE L'ENSEIGNEMENT TECHNIQUE Nouvelles Technologies en Tuyauteries Multicouches - French version only

    CERN Multimedia

    Davide Vitè

    2002-01-01

    Mardi 28 mai, mercredi 29 mai 28 mai, 9:30 - 12:00 - Training Centre Auditorium, Room 11, bldg. 593 28 mai, 14:00 - 17:00; 29 mai, 9:00 - 12:00 - Training Centre Rooms 13 and 15, bldg. 593 Nouvelles Technologies en Tuyauteries Multicouches Jacques Dougoud / GEBERIT SA, Lausanne, Suisse Mario Bettini / GEORG FISCHER PFCI S.r.l., Peschiera del Garda, Brescia, Italie Christian Tacco / VALSIR S.P.A., Vestone, Brescia, Italie Depuis quelques années l'apparition de tubes multicouches a changé radicalement la conception des tuyauteries, tant pour les applications industrielles que domestiques. Les utilisations au CERN concernent pratiquement tous les fluides, c'est-à-dire eau sanitaire, eau déminéralisée, air comprimé, fluorocarbones liquides ou gazeux, et tous les gaz, depuis l'hélium jusqu'au xénon. Ce séminaire de l'Enseignement Technique est adressé à toute personne concern&eac...

  2. Molecule Matters van der Waals Molecules

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 7. Molecule Matters van der Waals Molecules - Rg•••HF Complexes are Debye Molecules! E Arunan. Feature Article Volume 15 Issue 7 July 2010 pp 667-674. Fulltext. Click here to view fulltext PDF. Permanent link:

  3. How the Nouvelle Vague Invented the DVD: Cinephilia, new waves and film culture in the age of digital dissemination

    Directory of Open Access Journals (Sweden)

    Malte Hagener

    2014-01-01

    Full Text Available Whereas the currently emerging configurations of audiovisualcy in the age of digital networks are often addressed in terms of absolute novelty and innovation, this article wishes to shift the focus slightly, articulating instead the new in terms of the old. This essay proposes the argument that it was within the Nouvelle Vague and the French film culture of the 1960s that the DVD was “invented”. Obviously, this is a contrafactual argument, but if we understand the DVD as a discursive construction articulating a specific perspective on film, then the DVD simulates and emulates some key features of 1960s cinephilia that emerged within the context of the new waves. On the other hand, the Nouvelle Vague is understood as a broad discursive movement encompassing all segments of the institution cinema rather than five auteur-directors — Truffaut, Godard, Chabrol, Rohmer and Rivette — and their respective films. By arguing for the continuing importance of film history and culture, this article wishes to underline the fact that technological as well as aesthetic transformations are central to our understanding of media culture.

  4. Elaboration de nouvelles approches micromecaniques pour l'optimisation des performances mecaniques des materiaux heterogenes

    Science.gov (United States)

    Aboutajeddine, Ahmed

    Les modeles micromecaniques de transition d'echelles qui permettent de determiner les proprietes effectives des materiaux heterogenes a partir de la microstructure sont consideres dans ce travail. L'objectif est la prise en compte de la presence d'une interphase entre la matrice et le renforcement dans les modeles micromecaniques classiques, de meme que la reconsideration des approximations de base de ces modeles, afin de traiter les materiaux multiphasiques. Un nouveau modele micromecanique est alors propose pour tenir compte de la presence d'une interphase elastique mince lors de la determination des proprietes effectives. Ce modele a ete construit grace a l'apport de l'equation integrale, des operateurs interfaciaux de Hill et de la methode de Mori-Tanaka. Les expressions obtenues pour les modules globaux et les champs dans l'enrobage sont de nature analytique. L'approximation de base de ce modele est amelioree par la suite dans un nouveau modele qui s'interesse aux inclusions enrobees avec un enrobage mince ou epais. La resolution utilisee s'appuie sur une double homogeneisation realisee au niveau de l'inclusion enrobee et du materiau. Cette nouvelle demarche, permettra d'apprehender completement les implications des approximations de la modelisation. Les resultats obtenus sont exploites par la suite dans la solution de l'assemblage de Hashin. Ainsi, plusieurs modeles micromecaniques classiques d'origines differentes se voient unifier et rattacher, dans ce travail, a la representation geometrique de Hashin. En plus de pouvoir apprecier completement la pertinence de l'approximation de chaque modele dans cette vision unique, l'extension correcte de ces modeles aux materiaux multiphasiques est rendue possible. Plusieurs modeles analytiques et explicites sont alors proposee suivant des solutions de differents ordres de l'assemblage de Hashin. L'un des modeles explicite apparait comme une correction directe du modele de Mori-Tanaka, dans les cas ou celui ci echoue a

  5. Entre Classicisme et Modernité : La Nouvelle Revue Française dans le champ littéraire de la Belle Epoque

    NARCIS (Netherlands)

    Koffeman-Bijman, M.N.

    2003-01-01

    The literary review La Nouvelle Revue Française enjoys an enormous prestige in France. In Entre Classicisme et Modernité, Maaike Koffeman explores the origins of this legend of French literary life by means of a historical, literary and sociological analysis of the first years of the review s

  6. IFP Energies nouvelles - 2013 Activity Report. 2013 financial report. Innovating for energy

    International Nuclear Information System (INIS)

    2014-01-01

    IFP Energies nouvelles (IFPEN) is a public research and training player. It has an international scope, covering the fields of energy, transport and the environment. From research to industry, technological innovation is central to all its activities. As part of the public-interest mission with which it has been tasked by the public authorities, IFPEN focuses on: - providing solutions to take up the challenges facing society in terms of energy and the climate, promoting the emergence of a sustainable energy mix; - creating wealth and jobs by supporting French and European economic activity, and the competitiveness of related industrial sectors. IFPEN has proven expertise across the entire value chain, from fundamental research to industrial research and innovation. It is funded both by a state budget and by resources provided by French and foreign international partners. The aim of IFPEN's R and D programs is to overcome existing scientific and technological barriers in order to develop innovations that can be used by industry. Through its research and resulting innovations, IFPEN fosters the economic development of fields related to the energy, transport and eco-industry sectors. In so doing, it also contributes to creating wealth and jobs. IFPEN's innovations are developed industrially through close partnerships with industrial players and IFP Group subsidiaries. In both emerging and mature markets, IFPEN creates companies or acquires stakeholdings in companies of significant potential, either directly or via capital funds. In addition, IFPEN supports the development of SMEs and SMIs as part of collaboration agreements, contributing its technical and legal expertise. Representing over 50 professions, from geological engineers to power-train engineers, IFPEN's employees form a unique body of globally recognized scientific specialists and an unparalleled network of expertise. In order to carry out their research work at the cutting edge of innovation, they have

  7. 'Grenelle de l'environnement ' : peut-on se passer d'une nouvelle fiscalité écologique ?

    OpenAIRE

    Eloi Laurent; Jacques Le Cacheux

    2007-01-01

    Contrairement à ce qu'a affirmé Al Gore quand il a appris la nouvelle de son Prix Nobel de la paix, la lutte contre le changement climatique n'est pas avant tout une affaire morale, mais bien un enjeu politique, et plus précisément d'économie politique. C'est le problème des moyens, des instruments et des incitations que doit désormais poser et résoudre l'action publique, les travaux des lauréats du " Prix Nobel d'économie " pouvant d'ailleurs se révéler fort utiles dans cette optique pratiqu...

  8. Le télé-achat : finalité ou usage par défaut des nouvelles convergences ?

    OpenAIRE

    Lenoir , Christophe

    2000-01-01

    HAL : hal-00558853; International audience; Le télé-achat relève-t-il d'une finalité ou d'un usage par défaut des nouvelles convergences ? A partir des questions de détermination technologique et d'indétermination des usages, cet article propose, au vu de l'évolution économique du secteur et de l'information économique véhiculée par ses agents, de s'interroger sur les conditions énonciatives de ces processus de communication et leurs conséquences sur le médium télévisuel.

  9. Literaire strategieën: de drie satellieten van La Nouvelle Revue Française (1910-1914

    Directory of Open Access Journals (Sweden)

    Maaike Koffeman

    2000-12-01

    Full Text Available La Nouvelle Revue Française, opgericht in 1908 door een groep schrijvers rond André Gide, is het belangrijkste Franse literaire maandblad van het interbellum geweest. In de jaren voorafgaand aan de Eerste Wereldoorlog is de reputatie van het tijdschrift nog relatief bescheiden, maar er is al wel een duidelijke progressie te constateren. Deze is niet alleen toe te schrijven aan de inhoudelijke kwaliteit van de bijdragen, maar vooral ook aan de manier waaorp de redactie het tijdschrift promoot. De oprichters bedienen zich van een 'mutimedia-strategie': zij ontwikkelen rond de NRF verschillende nevenactiviteiten om de naamsbekendheid van het tijdschrift te vergroten en zijn literatuuropvattingen onder een breder publiek te verspreiden. 

  10. Nouvelle procédure pour l'augmentation du temps d'usinage simulé en coupe orthogonale

    OpenAIRE

    Guediche , Mayssa; Mabrouki , Tarek; Donnet , Christophe; Bergheau , Jean-Michel; Hamdi , Hedi

    2015-01-01

    International audience; Cette étude présente une nouvelle méthodologie visant à augmenter le temps d'usinage simulé en coupe orthogonale .Le but est d'étudier ultérieurement l'évolution de l'usure des outils de coupe dans le cas de l'usinage de l'acier 42CD4. Un modèle lagrangien est donc développé sous le code de calcul ABAQUS simulant la formation du copeau. Une approche baptisée de « modélisation verticale » est développée dans le but d'augmenter le temps de coupe simulé tout en gardant un...

  11. Test des photomultiplicateurs en silicium couplés à un scintillateur plastique pour la nouvelle Tape Station

    CERN Document Server

    sekal, Smain

    2014-01-01

    L’une des parties essentielles de la l’installation ISOLDE est la tape Station (contrôleur de bandes), qui permet la vérification de la qualité du faisceau délivré aux expériences. On prévoit à ISOLDE de remplacer l’ancienne Tape Station, par une nouvelle Tape station; et l’un des paramètres essentiels pour la performance de la tape Station est l’efficacité de détection. Le but de ce travail est de vérifier l’efficacité des détecteurs de particules bêta, composés par l’association des photomultiplicateurs en Silicium à un scintillateur plastique pour differentes distances.

  12. Les théosophes et l’organisation internationale de l’éducation nouvelle (1911-1921

    Directory of Open Access Journals (Sweden)

    Sylvain Wagnon

    2017-01-01

    Full Text Available The historic importance of Theosophy within the realm of education is due to their presence in their reflexions and educational endeavours are at the origins of that nebulous movement called the New Education (éducation nouvelle. Their presence at the beginning of the organization of the New Education has been explored by several pioneering papers, but remains the blind spot in this area. In fact Theosophy’s influence has been felt but rarely analysed as the matrix of the nebulous international organization of new education. If the Theosophists’ influence were to be recognised, we think that their role, their persistent work that brought on not only the rise of new education, more specifically, the constitution of the International League of New Education but was also the making of educators of Theosophy teachings such as María Montessori and Rudolf Steiner who were not only the roots of the new education but also its main components.

  13. Formation of Ultracold Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Cote, Robin [Univ. of Connecticut, Storrs, CT (United States)

    2016-01-28

    Advances in our ability to slow down and cool atoms and molecules to ultracold temperatures have paved the way to a revolution in basic research on molecules. Ultracold molecules are sensitive of very weak interactions, even when separated by large distances, which allow studies of the effect of those interactions on the behavior of molecules. In this program, we have explored ways to form ultracold molecules starting from pairs of atoms that have already reached the ultracold regime. We devised methods that enhance the efficiency of ultracold molecule production, for example by tuning external magnetic fields and using appropriate laser excitations. We also investigates the properties of those ultracold molecules, especially their de-excitation into stable molecules. We studied the possibility of creating new classes of ultra-long range molecules, named macrodimers, thousand times more extended than regular molecules. Again, such objects are possible because ultra low temperatures prevent their breakup by collision. Finally, we carried out calculations on how chemical reactions are affected and modified at ultracold temperatures. Normally, reactions become less effective as the temperature decreases, but at ultracold temperatures, they can become very effective. We studied this counter-intuitive behavior for benchmark chemical reactions involving molecular hydrogen.

  14. The status of molecules

    International Nuclear Information System (INIS)

    Barnes, T.; Oak Ridge National Lab., TN; Tennessee Univ., Knoxville, TN

    1994-06-01

    This report summarizes the experimental and theoretical status of hadronic molecules, which are weakly-bound states of two or more hadrons. We begin with a brief history of the subject and discuss a few good candidates, and then abstract some signatures for molecules which may be of interest in the classification of possible molecule states. Next we argue that a more general understanding of 2 → 2 hadron-hadron scattering amplitudes will be crucial for molecule searches, and discuss some of our recent work in this area. We conclude with a discussion of a few more recent molecule candidates (notably the f o (1710)) which are not well established as molecules but satisfy some of the expected signatures. (Author)

  15. Cold Rydberg molecules

    Science.gov (United States)

    Raithel, Georg; Zhao, Jianming

    2017-04-01

    Cold atomic systems have opened new frontiers at the interface of atomic and molecular physics. These include research on novel types of Rydberg molecules. Three types of molecules will be reviewed. Long-range, homonuclear Rydberg molecules, first predicted in [1] and observed in [2], are formed via low-energy electron scattering of the Rydberg electron from a ground-state atom within the Rydberg atom's volume. The binding mostly arises from S- and P-wave triplet scattering. We use a Fermi model that includes S-wave and P-wave singlet and triplet scattering, the fine structure coupling of the Rydberg atom and the hyperfine structure coupling of the 5S1/2 atom (in rubidium [3]). The hyperfine structure gives rise to mixed singlet-triplet potentials for both low-L and high-L Rydberg molecules [3]. A classification into Hund's cases [3, 4, 5] will be discussed. The talk further includes results on adiabatic potentials and adiabatic states of Rydberg-Rydberg molecules in Rb and Cs. These molecules, which have even larger bonding length than Rydberg-ground molecules, are formed via electrostatic multipole interactions. The leading interaction term of neutral Rydberg-Rydberg molecules is between two dipoles, while for ionic Rydberg molecules it is between a dipole and a monopole. NSF (PHY-1506093), NNSF of China (61475123).

  16. Molecule of the Month

    Indian Academy of Sciences (India)

    Atoms in a molecule generally prefer, particularly among the neighbouring ones, certain optimmn geometrical relationships. These are manifested in specific ranges of bond lengths, bond angles, torsion angles etc. As it always happens, chemists are interested in making molecules where these 'standard relationships' are ...

  17. Molecule of the Month

    Indian Academy of Sciences (India)

    Cyclo bu tadiene (1) has been one of the most popular molecules for experimentalists and theoreticians. This molecule is unstable as . it is antiaromatic ( 4,n electrons in a cyclic array). Even though some highly substituted cyclobutadienes, for example, compound 2 and the Fe(CO)3 complex of cyclobutadiene (3) are ...

  18. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 20; Issue 2. Single-Molecule Spectroscopy: Every Molecule is Different! Kankan Bhattacharyya. General Article Volume 20 Issue 2 February 2015 pp 151-164. Fulltext. Click here to view fulltext PDF. Permanent link:

  19. Single molecule conductance

    NARCIS (Netherlands)

    Willems, R.

    2008-01-01

    This thesis represents an excursion into the world of molecular electronics, i.e. the field of research trying to use individual (organic) molecules as electronic components; in this work various experimental methods have been explored to connect individual molecules to metallic contacts and

  20. Molecules in stars

    International Nuclear Information System (INIS)

    Tsuji, T.

    1986-01-01

    Recently, research related to molecules in stars has rapidly expanded because of progress in related fields. For this reason, it is almost impossible to cover all the topics related to molecules in stars. Thus, here the authors focus their attention on molecules in the atmospheres of cool stars and do not cover in any detail topics related to circumstellar molecules originating from expanding envelopes located far from the stellar surface. However, the authors do discuss molecules in quasi-static circumstellar envelopes (a recently discovered new component of circumstellar envelopes) located near the stellar surface, since molecular lines originating from such envelopes show little velocity shift relative to photospheric lines, and hence they directly affect the interpretation and analysis of stellar spectra

  1. La banque de la Nouvelle-Calédonie. Existence éphémère, expérience oubliée (1874-1877)

    OpenAIRE

    Buttet, Catherine

    2009-01-01

    La Nouvelle-Calédonie, colonie pénale peu peuplée, était en 1870 tributaire des commerçants et du Trésor public pour l'ensemble des opérations bancaires. Née d'une société de colonisation d'initiative privée, la Banque de la Nouvelle-Calédonie fut une expérience distincte des anciennes banques coloniales et dont le nouveau cadre statutaire servit ensuite à la Banque d'Indochine. La banque reçut l'aval du gouvernement sous la forme d'une autorisation puis d'un privilège. Rapidement, la banque ...

  2. L’hybridation interspécifique chez les champignons phytopathogènes à l’origine de nouvelles maladies

    OpenAIRE

    Frey, Pascal

    2009-01-01

    Mécanisme évolutif bien connu chez les plantes, l’hybridation interspécifique a été relativement peu étudiée dans certains groupes taxonomiques, comme les champignons. Chez les champignons phytopathogènes, l’hybridation entre une espèce indigène et une espèce exotique peut pourtant conduire à l’émergence de nouvelles maladies des plantes.

  3. Crenicichla tigrina, Une nouvelle espèce de cichlidae (Pisces, Perciformes) du Rio Trombetas, Pará, Brésil

    NARCIS (Netherlands)

    Ploeg, Alex; Jégu, Michael; Ferreira, Efrem

    1991-01-01

    Une nouvelle espèce de Cichlidae, Crenicichla tigrina, est décrite et illustrée. La coloration sur le vivant et quelques remarques relatives à l’Pecologie de cette espèce sont présentée. Les relations de C. tigrina avec les autres espèces de Crenicichla à petites écailles et le mode de distribution

  4. Dynamics of Activated Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Mullin, Amy S. [Univ. of Maryland, College Park, MD (United States)

    2016-11-16

    Experimental studies have been performed to investigate the collisional energy transfer processes of gas-phase molecules that contain large amounts of internal energy. Such molecules are prototypes for molecules under high temperature conditions relevant in combustion and information about their energy transfer mechanisms is needed for a detailed understanding and modeling of the chemistry. We use high resolution transient IR absorption spectroscopy to measure the full, nascent product distributions for collisions of small bath molecules that relax highly vibrationally excited pyrazine molecules with E=38000 cm-1 of vibrational energy. To perform these studies, we developed new instrumentation based on modern IR light sources to expand our experimental capabilities to investigate new molecules as collision partners. This final report describes our research in four areas: the characterization of a new transient absorption spectrometer and the results of state-resolved collision studies of pyrazine(E) with HCl, methane and ammonia. Through this research we have gained fundamental new insights into the microscopic details of relatively large complex molecules at high energy as they undergo quenching collisions and redistribute their energy.

  5. Dissociation in small molecules

    International Nuclear Information System (INIS)

    Dehmer, P.M.

    1982-01-01

    The study of molecular dissociation processes is one of the most interesting areas of modern spectroscopy owing to the challenges presented bt even the simplest of diatomic molecules. This paper reviews the commonly used descriptions of molecular dissociation processes for diatomic molecules, the selection rules for predissociation, and a few of the principles to be remembered when one is forced to speculate about dissociation mechanisms in a new molecule. Some of these points will be illustrated by the example of dissociative ionization in O 2

  6. The English Democrats Party ou l’émergence d’une nouvelle mouvance : le nationalisme autonomiste anglais

    Directory of Open Access Journals (Sweden)

    Claude BARBANTI

    2011-03-01

    Full Text Available La réforme dite de dévolution (décentralisation, votée en 1997, a entraîné de multiples conséquences et transformations dans la vie politique britannique. Le système traditionnellement unitaire de Westminster s’en est trouvé profondément bouleversé. Pourtant, tandis que de nombreuses études furent menées sur les divers nouveaux aspects d’une Grande-Bretagne dévolue, peu se sont penchées sur les conséquences de cette nouvelle asymétrie constitutionnelle sur l’Angleterre. Lorsque des députés de circonscriptions « celtiques » (en Écosse ou au pays de Galles arrivent à influencer le résultat de votes sur des affaires exclusivement anglaises, certains députés d’Angleterre, à Westminster, ne peuvent que se sentir désarmés face au manque de dispositions constitutionnelles garantissant un statut particulier pour ce territoire. Dès lors, de cette « question anglaise » (« English Question », naîtra toute une nouvelle mouvance autonomiste entièrement dédiée à l’obtention d’un Parlement anglais.Devolution at the end of the 1990s has led to numerous consequences and transformations in British politics. The traditional and centralised Westminster system has been turned upside down, and many studies have been carried out on the various aspects of this new “devolved Britain”.Yet, few have paid attention to the English case. However, the constitutional asymmetry thus created has indeed also affected England. When Celtic MPs succeed to influence the outcome of votes on exclusively English matters, one can realise that there is no such thing as an English government. Therefore, some English MPs have felt the need to ask for an option of “English Votes on English Laws”. This article tries to demonstrate that a feeling of “resentment” emerges from this situation and leads to the birth of a new “English” nationalism, entirely dedicated to obtaining an English Parliament.

  7. La mosquée en Algérie.Figures nouvelles et pratiques reconstituées

    Directory of Open Access Journals (Sweden)

    Abderrahmane Moussaoui

    2012-07-01

    Full Text Available La « globalisation » des discours de la mosquée casse les frontières érigées historiquement par les différentes écoles, et tend à réduire la fracture inaugurale entre sunnisme et chiisme. Aujourd’hui il y a un retour à la Salafiya qui ne reconnaît que les fondamentaux. Tout le reste est considéré comme de l’ordre de l’historique et donc non sacré et à ce titre susceptible d’être laissé de côté ou changé. La Salafiya continue cependant à être divisée entre djâmida et djihâdiya.Les pratiques au sein de la mosquée procèdent également par pluralisation où l’individu cherche à la fois à signaler son individualité mais aussi à s’inscrire dans des tendances plus globales. Les récits de vie de différents imams laisse transparaître une sorte de sécularisation interne de la mosquée et une plus grande latitude dans la ré interprétation de l’initial.Les changements sont perceptibles également au niveau des acteurs De nouvelles figures concurrencent celle classique de l’imam. Le prédicateur, sans être une figure tout à fait nouvelle, ni une invention récente, demeure une figure réinventée. Au Maghreb, on connaît l’imam, le mufti, le taleb, mais moins le dâ`îya que les chaînes de télévision à thématique religieuse ont fini par imposer.Ce sont toutes ces transformations qui se déroulent au cœur de l’institution la plus significative de l’Islam que tente d’examiner cette contribution.

  8. Single molecules and nanotechnology

    CERN Document Server

    Vogel, Horst

    2007-01-01

    This book focuses on recent advances in the rapidly evolving field of single molecule research. These advances are of importance for the investigation of biopolymers and cellular biochemical reactions, and are essential to the development of quantitative biology. Written by leading experts in the field, the articles cover a broad range of topics, including: quantum photonics of organic dyes and inorganic nanoparticles their use in detecting properties of single molecules the monitoring of single molecule (enzymatic) reactions single protein (un)folding in nanometer-sized confined volumes the dynamics of molecular interactions in biological cells The book is written for advanced students and scientists who wish to survey the concepts, techniques and results of single molecule research and assess them for their own scientific activities.

  9. Electron-molecule collisions

    CERN Document Server

    Takayanagi, Kazuo

    1984-01-01

    Scattering phenomena play an important role in modern physics. Many significant discoveries have been made through collision experiments. Amongst diverse kinds of collision systems, this book sheds light on the collision of an electron with a molecule. The electron-molecule collision provides a basic scattering problem. It is scattering by a nonspherical, multicentered composite particle with its centers having degrees of freedom of motion. The molecule can even disintegrate, Le., dissociate or ionize into fragments, some or all of which may also be molecules. Although it is a difficult problem, the recent theoretical, experimental, and computational progress has been so significant as to warrant publication of a book that specializes in this field. The progress owes partly to technical develop­ ments in measurements and computations. No less important has been the great and continuing stimulus from such fields of application as astrophysics, the physics of the earth's upper atmosphere, laser physics, radiat...

  10. Molecules to Materials

    Indian Academy of Sciences (India)

    evolved as a new line of thinking wherein a single molecule or perhaps a collection .... In photonic communication processes, laser light has to be modulated and .... The author wishes to thank G Rajaram for a critical reading of the manuscript.

  11. Single-Molecule Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    overall absorption spectrum of a molecule is a superposition of many such sharp lines .... dilute solution of the enzyme and the substrate over few drops of silicone oil placed ..... Near-field Scanning Optical Microscopy (NSOM): Development.

  12. Quantum dot molecules

    CERN Document Server

    Wu, Jiang

    2014-01-01

    This book reviews recent advances in the exciting and rapidly growing field of quantum dot molecules (QDMs). It offers state-of-the-art coverage of novel techniques and connects fundamental physical properties with device design.

  13. Molecule of the Month

    Indian Academy of Sciences (India)

    Molecule of the Month - Adamantane - A Plastic Piece of Diamond. J Chandrasekhar. Volume 16 Issue 12 ... Keywords. Adamantane; diamondoid systems; plastic crystals. ... Resonance – Journal of Science Education | News. © 2017 Indian ...

  14. New methods and applications in emission spectroscopy (1960); Methodes et applications nouvelles en spectroscopie d'emission (1960)

    Energy Technology Data Exchange (ETDEWEB)

    Baudin, G [Commissariat a l' Energie Atomique, Grenoble (France).Centre d' Etudes Nucleaires

    1960-07-01

    Emission spectroscopy, are already well-established instrumental analytical technique, has in recent years known important developments. Two mains factors are responsible; firstly the demands of metallurgy for purer and purer materials or alloys which are increasingly complex and difficult to analyse by chemical means; secondly, progress in optics, especially in the production of gratings, and in electronics in the field of photomultiplier tubes. We will not here catalogue all the new applications and methods, but we will consider a few amongst the most representative outside the conventional field. (author) [French] La spectroscopie d'emission, technique analytique instrumentale deja ancienne, a pris, depuis quelques annees, une extension notable. Deux facteurs principaux ont contribue a ce succes: d'une part, l'exigence de la metallurgie en materiaux de plus en plus pur ou en alliages de plus en plus complexes, difficiles a analyser chimiquement, d'autre part, les progres realises en optique, principalement dans la fabrication des reseaux, et en electronique dans le domaine des tubes photomultiplicateurs. Nous ne ferons pas ici le recensement de toutes les applications ou methodes nouvelles, mais nous en choisirons quelques unes des plus representatives hors du domaine classique. (auteur)

  15. Electron-molecule collisions

    International Nuclear Information System (INIS)

    Shimamura, I.; Takayanagi, K.

    1984-01-01

    The study of collision processes plays an important research role in modern physics. Many significant discoveries have been made by means of collision experiments. Based on theoretical, experimental, and computational studies, this volume presents an overview detailing the basic processes of electron-molecule collisions. The editors have collected papers-written by a group of international experts-that consider a diverse range of phenomena occurring in electronmolecule collisions. The volume discusses first the basic formulation for scattering problems and then gives an outline of the physics of electron-molecule collisions. The main topics covered are rotational transitions, vibrational transitions, dissociation of molecules in slow collisions, the electron-molecule collision as a spectroscopic tool for studying molecular electronic structures, and experimental and computational techniques for determining the cross sections. These well-referenced chapters are self-contained and can be read independently or consecutively. Authoritative and up-to-date, Electron-Molecule Collisions is a useful addition to the libraries of students and researchers in the fields of atomic, molecular, and chemical physics, and physical chemistry

  16. MODIFICACION QUIMICA DEL POLIPROPILENO Y SU POTENCIAL USO COMO AGENTE EXTRACTANTE DE IONES METALICOS.

    OpenAIRE

    PEREZ AMARO, LUCIA GABRIELA; PEREZ AMARO, LUCIA GABRIELA

    2008-01-01

    Es de interés en la presente tesis doctoral ampliar el campo de aplicación del polipropileno isotáctico homopolímero (PP) basándose en las propiedades mecánicas, químicas y el bajo costo de producción del polímero. Las excelentes propiedades mecánicas car 176p.

  17. MOLECULES IN η CARINAE

    International Nuclear Information System (INIS)

    Loinard, Laurent; Menten, Karl M.; Güsten, Rolf; Zapata, Luis A.; Rodríguez, Luis F.

    2012-01-01

    We report the detection toward η Carinae of six new molecules, CO, CN, HCO + , HCN, HNC, and N 2 H + , and of two of their less abundant isotopic counterparts, 13 CO and H 13 CN. The line profiles are moderately broad (∼100 km s –1 ), indicating that the emission originates in the dense, possibly clumpy, central arcsecond of the Homunculus Nebula. Contrary to previous claims, CO and HCO + do not appear to be underabundant in η Carinae. On the other hand, molecules containing nitrogen or the 13 C isotope of carbon are overabundant by about one order of magnitude. This demonstrates that, together with the dust responsible for the dimming of η Carinae following the Great Eruption, the molecules detected here must have formed in situ out of CNO-processed stellar material.

  18. Electron Accumulative Molecules.

    Science.gov (United States)

    Buades, Ana B; Sanchez Arderiu, Víctor; Olid-Britos, David; Viñas, Clara; Sillanpää, Reijo; Haukka, Matti; Fontrodona, Xavier; Paradinas, Markos; Ocal, Carmen; Teixidor, Francesc

    2018-02-28

    With the goal to produce molecules with high electron accepting capacity and low reorganization energy upon gaining one or more electrons, a synthesis procedure leading to the formation of a B-N(aromatic) bond in a cluster has been developed. The research was focused on the development of a molecular structure able to accept and release a specific number of electrons without decomposing or change in its structural arrangement. The synthetic procedure consists of a parallel decomposition reaction to generate a reactive electrophile and a synthesis reaction to generate the B-N(aromatic) bond. This procedure has paved the way to produce the metallacarboranylviologen [M(C 2 B 9 H 11 )(C 2 B 9 H 10 )-NC 5 H 4 -C 5 H 4 N-M'(C 2 B 9 H 11 )(C 2 B 9 H 10 )] (M = M' = Co, Fe and M = Co and M' = Fe) and semi(metallacarboranyl)viologen [3,3'-M(8-(NC 5 H 4 -C 5 H 4 N-1,2-C 2 B 9 H 10 )(1',2'-C 2 B 9 H 11 )] (M = Co, Fe) electron cumulative molecules. These molecules are able to accept up to five electrons and to donate one in single electron steps at accessible potentials and in a reversible way. By targeted synthesis and corresponding electrochemical tests each electron transfer (ET) step has been assigned to specific fragments of the molecules. The molecules have been carefully characterized, and the electronic communication between both metal centers (when this situation applies) has been definitely observed through the coplanarity of both pyridine fragments. The structural characteristics of these molecules imply a low reorganization energy that is a necessary requirement for low energy ET processes. This makes them electronically comparable to fullerenes, but on their side, they have a wide range of possible solvents. The ET from one molecule to another has been clearly demonstrated as well as their self-organizing capacity. We consider that these molecules, thanks to their easy synthesis, ET, self-organizing capacity, wide range of solubility, and easy processability, can

  19. Molecule of the Month

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 1; Issue 2. Molecule of the Month Isomers of Benzene - Still Pursuing Dreams. J Chandrasekhar. Feature Article Volume 1 Issue 2 February 1996 pp 80-83. Fulltext. Click here to view fulltext PDF. Permanent link:

  20. Atoms, Molecules, and Compounds

    CERN Document Server

    Manning, Phillip

    2007-01-01

    Explores the atoms that govern chemical processes. This book shows how the interactions between simple substances such as salt and water are crucial to life on Earth and how those interactions are predestined by the atoms that make up the molecules.

  1. Electrons in Molecules

    Indian Academy of Sciences (India)

    structure and properties (includingreactivt'ty) - both static (independent of time) and ... Furthermore, since the energy of H2 + in the ground state must be lower than that of .... (Figure 2b); note also that dp is positive in parts of the antibinding regions behind the two ... But, now both the sizes and shapes of molecules enter into.

  2. Molecule of the Month

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Molecule of the Month - A Stable Dibismuthene - A Compound with a Bi-Bi Double Bond. V Chandrasekhar. Volume 16 ... Author Affiliations. V Chandrasekhar1. Department of Chemistry, Indian Institute of Technology, Kanpur 208 016, India.

  3. OMG: Open molecule generator

    NARCIS (Netherlands)

    Peironcely, J.E.; Rojas-Chertó, M.; Fichera, D.; Reijmers, T.; Coulier, L.; Faulon, J.-L.; Hankemeier, T.

    2012-01-01

    Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG), which for a given elemental composition produces all non-isomorphic chemical

  4. Molecule-based magnets

    Indian Academy of Sciences (India)

    Administrator

    Employing self-assembly methods, it is possible to engineer a bulk molecular material ... synthesis of molecular magnets in 1986, a large variety of them have been synthesized, which can be catego- ... maintained stably per organic molecule, stabilization of a ..... rotating freely under an applied field because it is a magne-.

  5. Molecule of the Month

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 5. Molecule of the Month Molecular–Chameleon: Solvatochromism at its Iridescent Best! Photon Rao. Feature Article Volume 2 Issue 5 May 1997 pp 69-72. Fulltext. Click here to view fulltext PDF. Permanent link:

  6. Exotic helium molecules

    International Nuclear Information System (INIS)

    Portier, M.

    2007-12-01

    We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range 4 He 2 (2 3 S 1 -2 3 P 0 ) molecule, or a 4 He 2 (2 3 S 1 -2 3 S 1 ) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 ± 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range 4 He 2 (2 3 S 1 -2 3 S 1 ) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime τ = (1.4 ± 0.3) μs is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

  7. OMG: Open Molecule Generator.

    Science.gov (United States)

    Peironcely, Julio E; Rojas-Chertó, Miguel; Fichera, Davide; Reijmers, Theo; Coulier, Leon; Faulon, Jean-Loup; Hankemeier, Thomas

    2012-09-17

    Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG), which for a given elemental composition produces all non-isomorphic chemical structures that match that elemental composition. Furthermore, this structure generator can accept as additional input one or multiple non-overlapping prescribed substructures to drastically reduce the number of possible chemical structures. Being open source allows for customization and future extension of its functionality. OMG relies on a modified version of the Canonical Augmentation Path, which grows intermediate chemical structures by adding bonds and checks that at each step only unique molecules are produced. In order to benchmark the tool, we generated chemical structures for the elemental formulas and substructures of different metabolites and compared the results with a commercially available structure generator. The results obtained, i.e. the number of molecules generated, were identical for elemental compositions having only C, O and H. For elemental compositions containing C, O, H, N, P and S, OMG produces all the chemically valid molecules while the other generator produces more, yet chemically impossible, molecules. The chemical completeness of the OMG results comes at the expense of being slower than the commercial generator. In addition to being open source, OMG clearly showed the added value of constraining the solution space by using multiple prescribed substructures as input. We expect this structure generator to be useful in many fields, but to be especially of great importance for metabolomics, where identifying unknown metabolites is still a major bottleneck.

  8. OMG: Open Molecule Generator

    Directory of Open Access Journals (Sweden)

    Peironcely Julio E

    2012-09-01

    Full Text Available Abstract Computer Assisted Structure Elucidation has been used for decades to discover the chemical structure of unknown compounds. In this work we introduce the first open source structure generator, Open Molecule Generator (OMG, which for a given elemental composition produces all non-isomorphic chemical structures that match that elemental composition. Furthermore, this structure generator can accept as additional input one or multiple non-overlapping prescribed substructures to drastically reduce the number of possible chemical structures. Being open source allows for customization and future extension of its functionality. OMG relies on a modified version of the Canonical Augmentation Path, which grows intermediate chemical structures by adding bonds and checks that at each step only unique molecules are produced. In order to benchmark the tool, we generated chemical structures for the elemental formulas and substructures of different metabolites and compared the results with a commercially available structure generator. The results obtained, i.e. the number of molecules generated, were identical for elemental compositions having only C, O and H. For elemental compositions containing C, O, H, N, P and S, OMG produces all the chemically valid molecules while the other generator produces more, yet chemically impossible, molecules. The chemical completeness of the OMG results comes at the expense of being slower than the commercial generator. In addition to being open source, OMG clearly showed the added value of constraining the solution space by using multiple prescribed substructures as input. We expect this structure generator to be useful in many fields, but to be especially of great importance for metabolomics, where identifying unknown metabolites is still a major bottleneck.

  9. Nouvelles Techniques d'Intervention sur la Corrosion des Armatures du Béton Armé

    CERN Document Server

    Colloca, C

    1999-01-01

    Les principaux dégâts constatés dans les armatures passives du béton armé sont la corrosion généralisée et la corrosion locale. Ces dégradations sont provoquées soit par la carbonatation du béton soit par le contact avec l'eau pure ou l'eau chargée de chlorures pénétrant dans les pores et dans les fissures de surface. Ce document présente de nouvelles techniques d'intervention, fondées sur d'anciens principes, introduites pour le traitement électrochimique des zones altérées liées aux différentes conditions. La réalcalinisation (dans le cas de béton carbonaté) permet d'augmenter le pH du béton et de rétablir un niveau de basicité garantissant la passivation de l'armature. La désalification (dans le cas de béton entamé par les chlorures) provoque l'élimination des ions chlorure à travers la surface du béton. Les avantages de ces traitements, par rapport aux anciennes techniques, sont appréciables si l'on considère la durée d'exécution et leur coût moins élevé.

  10. New method of determining the thermal utilization factor of a cell; Nouvelle methode de determination du facteur d'utilisation thermique d'une cellule

    Energy Technology Data Exchange (ETDEWEB)

    Amouyal, A; Benoist, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1956-07-01

    A new formula for the thermal utilization factor is derived, which, while comparable in simplicity to the formula given by elementary diffusion theory, furnishes much more precise results. This is clearly brought out by comparison with the results given by the S{sub n} and spherical harmonics methods. (author) [French] Une nouvelle expression du facteur d'utilisation thermique, d'une simplicite comparable a celle de Ia theorie elementaire, est etablie. La comparaison avec les resultats fournis par la methode S{sub n} et les methodes d'harmoniques spheriques montre que la precision obtenue par cette formule est tres superieure a celle que donne la theorie elementaire. (auteur)

  11. Yankaya Dilek, La nouvelle bourgeoisie islamique. Le modèle turc, Presses universitaires de France, coll. Proche Orient, 2013, 216 p.

    OpenAIRE

    Özatalay , Cem

    2014-01-01

    International audience; Paru en mars 2013, le livre de Dilek Yankaya intitulé La nouvelle bourgeoisie islamique. Le modèle turc apporte une contribution remarquable pour comprendre les dynamiques sociales qui sous-tendent la polarisation politique et culturelle qui marque tout autant l’histoire récente de la Turquie que les événements de Gezi. En mettant en lumière les aspirations et la conscience de classe de la bourgeoisie islamique en formation, Yankaya essaie de montrer dans son ouvrage c...

  12. MOOCs et mobilités étudiantes : vers une nouvelle circulation des connaissances ? Observations au regard de l&8217;Afrique francophone

    OpenAIRE

    Meyer, Jean-Baptiste

    2017-01-01

    Les discours actuels sur l'internationalisation de l'enseignement supérieur font grand cas des cours à distance en diffusion libre et massive. Ils offrent des possibilités nouvelles de transmettre des connaissances élaborées, à un grand nombre de personnes, et sans recours à d'autres supports qu'un ordinateur connecté. Ces modalités en font un outil prometteur de transfert ou de partage international, puisque les frontières des pays sont effacées par la transmission numérique. Elles peuvent d...

  13. Single-Molecule Nanomagnets

    Science.gov (United States)

    Friedman, Jonathan R.; Sarachik, Myriam P.

    2010-04-01

    Single-molecule magnets straddle the classical and quantum mechanical worlds, displaying many fascinating phenomena. They may have important technological applications in information storage and quantum computation. We review the physical properties of two prototypical molecular nanomagnets, Mn12-acetate and Fe8: Each behaves as a rigid, spin-10 object and exhibits tunneling between up and down directions. As temperature is lowered, the spin-reversal process evolves from thermal activation to pure quantum tunneling. At low temperatures, magnetic avalanches occur in which the magnetization of an entire sample rapidly reverses. We discuss the important role that symmetry-breaking fields play in driving tunneling and in producing Berry-phase interference. Recent experimental advances indicate that quantum coherence can be maintained on timescales sufficient to allow a meaningful number of quantum computing operations to be performed. Efforts are under way to create monolayers and to address and manipulate individual molecules.

  14. Superexcited states of molecules

    International Nuclear Information System (INIS)

    Nakamura, Hiroki; Takagi, Hidekazu.

    1990-01-01

    The report addresses the nature and major features of molecule's superexcited states, focusing on their involvement in dynamic processes. It also outlines the quantum defect theory which allows various processes involving these states to be treated in a unified way. The Rydberg state has close relation with an ionized state with a positive energy. The quantum defect theory interprets such relation. Specifically, the report first describes the quantum defect theory focusing on its basic principle. The multi-channel quantum defect theory is then outlined centering on how to describe a Rydberg-type superexcited state. Description of a dissociative double-electron excited state is also discussed. The quantum defect theory is based on the fact that the physics of the motion of a Rydberg electron vary with the region in the electron's coordinate space. Finally, various molecular processes that involve a superexcited state are addressed focusing on autoionization, photoionization, dissociative recombination and bonding ionization of diatomic molecules. (N.K.)

  15. Atoms, molecules & elements

    CERN Document Server

    Graybill, George

    2007-01-01

    Young scientists will be thrilled to explore the invisible world of atoms, molecules and elements. Our resource provides ready-to-use information and activities for remedial students using simplified language and vocabulary. Students will label each part of the atom, learn what compounds are, and explore the patterns in the periodic table of elements to find calcium (Ca), chlorine (Cl), and helium (He) through hands-on activities.

  16. Photonic Molecule Lasers Revisited

    Science.gov (United States)

    Gagnon, Denis; Dumont, Joey; Déziel, Jean-Luc; Dubé, Louis J.

    2014-05-01

    Photonic molecules (PMs) formed by coupling two or more optical resonators are ideal candidates for the fabrication of integrated microlasers, photonic molecule lasers. Whereas most calculations on PM lasers have been based on cold-cavity (passive) modes, i.e. quasi-bound states, a recently formulated steady-state ab initio laser theory (SALT) offers the possibility to take into account the spectral properties of the underlying gain transition, its position and linewidth, as well as incorporating an arbitrary pump profile. We will combine two theoretical approaches to characterize the lasing properties of PM lasers: for two-dimensional systems, the generalized Lorenz-Mie theory will obtain the resonant modes of the coupled molecules in an active medium described by SALT. Not only is then the theoretical description more complete, the use of an active medium provides additional parameters to control, engineer and harness the lasing properties of PM lasers for ultra-low threshold and directional single-mode emission. We will extend our recent study and present new results for a number of promising geometries. The authors acknowledge financial support from NSERC (Canada) and the CERC in Photonic Innovations of Y. Messaddeq.

  17. Interstellar molecules and masers

    International Nuclear Information System (INIS)

    Nguyen-Q-Rieu; Guibert, J.

    1978-01-01

    The study of dense and dark clouds, in which hydrogen is mostly in molecular form, became possible since the discovery of interstellar molecules, emitting in the centimeter and millimeter wavelengths. The molecular lines are generally not in local thermal equilibrium (LTE). Their intensity can often be explained by invoking a population inversion mechanism. Maser emission lines due to OH, H 2 O and SiO molecules are among the most intense molecular lines. The H 2 CO molecule, detected in absorption in front of the cold cosmic background radiation of 2.7 K, illustrates the inverse phenomenon, the antimaser absorption. For a radio transition of frequency v, the inversion rate Δn (relative population difference between the upper and lower level) as well as the maser gain can be determined from the radio observations. In the case of the OH lines in the 2 PIsub(3/2), J=3/2 state, the inversion rates approximately 1 to 2% derived from the observations, are comparable with those obtained in the laboratory. The determination of the excitation mechanisms of the masers, through the statistical equilibrium and radiative transfer equations, implies the knowledge of collisional and radiative transition probabilities. A pumping model, which can satisfactorily explain the radio observations of some interstellar OH clouds, will be discussed [fr

  18. Tecnologie dell’informazione e nuovi processi di vittimizzazione / Nouvelles technologies et processus de victimisation / Information technologies and new processes of victimisation

    Directory of Open Access Journals (Sweden)

    Marotta Gemma

    2012-08-01

    Full Text Available New technologies, on the one hand, have produced undeniable positive effects, from the acceleration of cultural diffusion to the communication between "worlds" previously unknown; on the other hand, they have become now an instrument to commit new crimes and deviants acts.In the article we will discuss the processes of victimization related to specific offenses (digital identity theft, online paedopornography, cyberstalking and to new forms of addiction due to the new media. The aim is to highlight the dangers of the misuse or abuse of new technologies.S'il est vrai que les nouvelles technologies de communication ont produit des effets positifs indéniables, comme l'accélération de la diffusion culturelle et l'échange entre « mondes » jusque-là inconnus, elles n'en sont pas moins devenues un moyen de commettre des actes déviants et criminels nouveaux.Cet article expose les processus de victimisation liés à certains crimes (comme l'usurpation d'identité, la pédopornographie en ligne, le cyber-harcèlement, et de nouvelles formes de dépendance, afin de mettre en évidence les dangers d'un usage pervers ou délictueux des nouveaux médias.

  19. Un littoral sableux en progradation : le lido entre Leucate et Port-la-Nouvelle (Aude, Golfe du Lion, France

    Directory of Open Access Journals (Sweden)

    Jean-Pierre Larue

    2009-11-01

    Full Text Available L'étude multichronique de photographies aériennes révèle que le lido entre Leucate et Port-la-Nouvelle (Aude a progradé d'environ 15 % en largeur, entre 1952 et 2008. L'analyse sédimentologique permet de montrer que cette progradation exceptionnelle en période d'élévation du niveau marin est due à la présence de barres pré-littorales volumineuses et bien alimentées par la dérive littorale et le transport éolien effectué par les vents de terre. Cependant, du fait de la montée actuelle du niveau marin (2,5 à 3 mm/an et malgré la poursuite de l'accrétion, le lido subit des inondations de plus en plus fréquentes entre le cordon actuel et l'ancien cordon romain.A kinematic study of vertical aerial photos taken between 1952 and 2008 reveals that the Leucate-Port-la-Nouvelle lido (Aude has prograded of about 15 % in width. A sedimentological analysis allows us to explain this accretion caused by drift and wind which supply abundant nearshore bars. In spite of this progradation, frequent floodings, favoured by sea level rise (2.5 to 3 mm-1.year, occur between the present coastal bar and the Roman barrier.

  20. Quark chemistry: charmonium molecules

    International Nuclear Information System (INIS)

    De Rujula, A.; Jaffe, R.L.

    1977-01-01

    The theoretical and experimental evidence for two quark-two antiquark hadrons is reviewed. Concentration is placed on predictions for S-wave ''charmonium molecules,'' built of a c anti c charmonium pair and a light quark-antiquark pair. Their spectrum and quantum numbers are predicted and an estimate of their decay couplings and their prediction in monochromatic pion decays from charmonium resonances produced in e + e - -annihilation is given. Some S-wave charmonium resonances should be detectable in these decays, but typical branching ratios are only at the 1% level. 19 references

  1. Une Nouvelle Forme d’Autobiographie dans Les Années d’Annie Ernaux: Autobiographie Impersonnelle

    Directory of Open Access Journals (Sweden)

    Seçil Yücedağ

    2017-12-01

    Full Text Available Annie Ernaux, considérée comme l’une des femmes écrivaines les plus célèbres du XXIe siècle, a exprimé l’angoisse commune de son âge et de son passé en rédigeant Les Années. Elle n’avait pas non seulement le but de décrire sa vie, mais aussi d’esquisser l’histoire de la société française à laquelle elle appartient. Lorsqu’elle est venue au monde en 1940, le monde était au seuil de la Seconde Guerre mondiale. Etant élevée dans cette atmosphère chaotique, elle a appris beaucoup de choses de sa société, de sa famille et de son environnement. Annie Ernaux a découvert le monde comme une jeune fille, une mère, une épouse et une grand-mère. Ses expériences sociales et familiales l’ont beaucoup mûrie et elle a commencé à rédiger ses pensées. Ses souvenirs ont fait partie de ses écritures autobiographiques. Dans Les Années, Annie Ernaux a profité de toutes ses expériences personnelles et sociales avec de différents moyens. Elle a essayé d’établir des liens entre l’histoire de sa vie et celle de la société. Elle a accordé une importance à la vie sociale plutôt que sa propre vie dans Les Années. Elle y a développé des propres techniques d’écriture en se servant des photos familiales et personnelles, d’un film, d’une vidéo, des marques de publicité, des chansons, d’un tableau, des notes de journal ainsi que des événements sociologiques et historiques. Elle a ainsi créé une nouvelle forme d’autobiographie : autobiographie impersonnelle.

  2. Nouvelle manga, mon amour. Reflexiones sobre la narración gráfica de historias cotidianas

    Directory of Open Access Journals (Sweden)

    Olalla Hernández Ranz

    2010-03-01

    Full Text Available Desde sus primeras manifestaciones hace más de un siglo, el cómic se ha ido consolidando como un género popular sobretodo dirigido a un lector juvenil. Su evidente atractivo entre los lectores ha hecho que algunos padres, educadores y profesionales del ámbito de la promoción de la lectura se plantearan el por qué de dicha afición, llegando a conclusiones erróneas como la creencia de que se trata de una lectura menor, dirigida esencialmente a la pura distracción de quien los lee. El manga, en concreto, es el género dentro del cómic que más se consume en occidente. Se ha convertido en un fructífero producto de mercado que deriva en videojuegos, series de televisión, películas de cine… Su gran acogida entre el público infantil y juvenil preocupa a mediadores por la supuesta carga violenta y sexual y la baja calidad literaria de sus obras. El presente propuesta tratará de deshacer algunos tópicos en relación con la concepción errónea la historieta nipona, a partir del estudio de un corpus de obras creadas por autores japoneses y europeos que quieren aportar un cómic de calidad tanto en su forma como en el contenido, abriendo así las puertas a nuevas investigaciones de gran interés. La Novelle manga es un nuevo género dentro del cómic nipón que aúna las estrategias comunicativas más destacables de las novelas gráficas japonesas, el valor estético del cómic francés y la sencillez y el tono de las películas de cine francés dentro de la Nouvelle Vague para crear un cómic que narra historias cotidianas de gran valor literario y estético, muy recomendable para lectores juveniles y adultos.

  3. Ultra-cold molecule production

    International Nuclear Information System (INIS)

    Ramirez-Serrano, Jamie; Chandler, David W.; Strecker, Kevin; Rahn, Larry A.

    2005-01-01

    The production of Ultra-cold molecules is a goal of many laboratories through out the world. Here we are pursuing a unique technique that utilizes the kinematics of atomic and molecular collisions to achieve the goal of producing substantial numbers of sub Kelvin molecules confined in a trap. Here a trap is defined as an apparatus that spatially localizes, in a known location in the laboratory, a sample of molecules whose temperature is below one degree absolute Kelvin. Further, the storage time for the molecules must be sufficient to measure and possibly further cool the molecules. We utilize a technique unique to Sandia to form cold molecules from near mass degenerate collisions between atoms and molecules. This report describes the progress we have made using this novel technique and the further progress towards trapping molecules we have cooled

  4. Passing Current through Touching Molecules

    DEFF Research Database (Denmark)

    Schull, G.; Frederiksen, Thomas; Brandbyge, Mads

    2009-01-01

    The charge flow from a single C-60 molecule to another one has been probed. The conformation and electronic states of both molecules on the contacting electrodes have been characterized using a cryogenic scanning tunneling microscope. While the contact conductance of a single molecule between two...

  5. Nouvelles techniques de mise en valeur des ressources d'hydrocarbures New Techniques for Valorising Hydrocarbon Resources

    Directory of Open Access Journals (Sweden)

    Boy De la Tour X.

    2006-11-01

    Full Text Available Après avoir montré l'importance des réserves de pétrole non conventionnel et l'enjeu que représente pour l'humanité la mise en exploitation de ces ressources, cette étude examine les axes actuels de recherches et l'état de la technologie pour chacune des sources de nouveau pétrole retenues : mers profondes, récupération assistée, huiles lourdes et sables asphaltiques, schistes bitumineux et conversion du charbon. Il en ressort que si les ressources de nouveau pétrole sont considérables, leur mise en valeur nécessitera des investissements très lourds, et le coût du pétrole ainsi produit restera élevé, comparé au coût actuel du pétrole conventionnel. Compte tenu des délais de mise en oeuvre, des problèmes technologiques restant à résoudre et de la nécessité de réaliser des pilotes semi-industriels très coûteux pour expérimenter les nouvelles techniques, il convient de consentir sans attendre un effort important de recherche technologique, impliquant un accroissement sensible des budgets de R&D, mais aussi des incitations financières appropriées. Cet effort de mise au point de technologies adaptées à ces sources d'hydrocarbures sera favorisé par les nouvelles conditions économiques créées par la rareté relative des réserves d'hydrocarbures classiques, à condition que les Etats, par leur politique, favorisent la production de ressources d'hydrocarbures à coût élevé. A l'heure actuelle, on peut évaluer la production de pétrole difficile à environ 100 Mt, l'essentiel étant réalisé dans le domaine des huiles lourdes et de la récupération assistée ; on estime que la production de nouveau pétrole pourrait représenter 200 à 350 Mt en 1990 et se situer entre 600 et 900 Mt en 2000, soit 5 à 8 % de la production de pétrole en 1990 et 15 à 20 % en 2000. Un tel objectif nécessiterait des investissements de l'ordre de 500 à 750 milliards de dollars 1980. After pointing out the importance of

  6. Lanthanide single molecule magnets

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Jinkui; Zhang, Peng [Chinese Academy of Sciences, Changchun (China). Changchun Inst. of Applied Chemistry

    2015-10-01

    This book begins by providing basic information on single-molecule magnets (SMMs), covering the magnetism of lanthanide, the characterization and relaxation dynamics of SMMs and advanced means of studying lanthanide SMMs. It then systematically introduces lanthanide SMMs ranging from mononuclear and dinuclear to polynuclear complexes, classifying them and highlighting those SMMs with high barrier and blocking temperatures - an approach that provides some very valuable indicators for the structural features needed to optimize the contribution of an Ising type spin to a molecular magnet. The final chapter presents some of the newest developments in the lanthanide SMM field, such as the design of multifunctional and stimuli-responsive magnetic materials as well as the anchoring and organization of the SMMs on surfaces. In addition, the crystal structure and magnetic data are clearly presented with a wealth of illustrations in each chapter, helping newcomers and experts alike to better grasp ongoing trends and explore new directions.

  7. Lanthanide single molecule magnets

    CERN Document Server

    Tang, Jinkui

    2015-01-01

    This book begins by providing basic information on single-molecule magnets (SMMs), covering the magnetism of lanthanide, the characterization and relaxation dynamics of SMMs, and advanced means of studying lanthanide SMMs. It then systematically introduces lanthanide SMMs ranging from mononuclear and dinuclear to polynuclear complexes, classifying them and highlighting those SMMs with high barrier and blocking temperatures – an approach that provides some very valuable indicators for the structural features needed to optimize the contribution of an Ising type spin to a molecular magnet. The final chapter presents some of the newest developments in the lanthanide SMM field, such as the design of multifunctional and stimuli-responsive magnetic materials as well as the anchoring and organization of the SMMs on surfaces. In addition, the crystal structure and magnetic data are clearly presented with a wealth of illustrations in each chapter, helping newcomers and experts alike to better grasp ongoing trends and...

  8. Molecules in the Spotlight

    Energy Technology Data Exchange (ETDEWEB)

    Cryan, James

    2010-01-26

    SLAC has just unveiled the world's first X-ray laser, the LCLS. This machine produces pulses of X-rays that are ten billion times brighter than those from conventional sources. One of the goals of this machine is to make movies of chemical reactions, including reactions necessary for life and reactions that might power new energy technologies. This public lecture will show the first results from the LCLS. As a first target, we have chosen nitrogen gas, the main component of the air we breathe. Using the unprecedented power of the LCLS X-rays as a blasting torch, we have created new forms of this molecule and with unique electronic arrangements. Please share with us the first insights from this new technology.

  9. Magnetic field modification of ultracold molecule-molecule collisions

    International Nuclear Information System (INIS)

    Tscherbul, T V; Suleimanov, Yu V; Aquilanti, V; Krems, R V

    2009-01-01

    We present an accurate quantum mechanical study of molecule-molecule collisions in the presence of a magnetic field. The work focuses on the analysis of elastic scattering and spin relaxation in collisions of O 2 ( 3 Σ g - ) molecules at cold (∼0.1 K) and ultracold (∼10 -6 K) temperatures. Our calculations show that magnetic spin relaxation in molecule-molecule collisions is extremely efficient except at magnetic fields below 1 mT. The rate constant for spin relaxation at T=0.1 K and a magnetic field of 0.1 T is found to be as large as 6.1x10 -11 cm -3 s -1 . The magnetic field dependence of elastic and inelastic scattering cross sections at ultracold temperatures is dominated by a manifold of Feshbach resonances with the density of ∼100 resonances per Tesla for collisions of molecules in the absolute ground state. This suggests that the scattering length of ultracold molecules in the absolute ground state can be effectively tuned in a very wide range of magnetic fields. Our calculations demonstrate that the number and properties of the magnetic Feshbach resonances are dramatically different for molecules in the absolute ground and excited spin states. The density of Feshbach resonances for molecule-molecule scattering in the low-field-seeking Zeeman state is reduced by a factor of 10.

  10. URGENCES NOUVELLE VERSION

    CERN Multimedia

    Medical Service

    2002-01-01

    The table of emergency numbers that appeared in Bulletin 10/2002 is out of date. The updated version provided by the Medical Service appears on the following page. Please disregard the previous version. URGENT NEED OF A DOCTOR GENEVAPATIENT NOT FIT TO BE MOVED: Call your family doctor Or SOS MEDECINS (24H/24H) 748 49 50 Or ASSOC. OF GENEVA DOCTORS (7H-23H) 322 20 20 PATIENT CAN BE MOVED: HOPITAL CANTONAL 24 Micheli du Crest 372 33 11 382 33 11 CHILDREN'S HOSPITAL 6 rue Willy Donzé 382 68 18 382 45 55 MATERNITY 24 Micheli du Crest 382 68 16 382 33 11 OPHTALMOLOGY 22 Alcide Jentzer 382 84 00 HOPITAL DE LA TOUR Meyrin 719 61 11 CENTRE MEDICAL DE MEYRIN Champs Fréchets 719 74 00 URGENCES : FIRE BRIGADE 118 FIRE BRIGADE CERN 767 44 44 BESOIN URGENT D'AMBULANCE (GENEVE ET VAUD) : 144 POLICE 117 ANTI-POISON CENTRE 24H/24H 01 251 51 510 EUROPEAN EMERGENCY CALL: 112 FRANCE PATIENT NOT FIT TO BE MOVED: call your family doctor PATIENT CAN BE MOVED: ST. JULIE...

  11. Vie-Nouvelle

    African Journals Online (AJOL)

    Chrystelle ATINKPAHOUN

    influent of wastewater treatment plant, greywater, etc. (Kafi et al. ... pollutant loadings related to suspended solids, bound metal ... treatment system for the domestic wastewater. (greywater and ...... thesis, Polytechnic Institute of Lorraine,. Nancy ...

  12. Tradition et innovations esthétiques dans la nouvelle yéménite contemporaine Tradition and aesthetic innovations in contemporary Yemeni short stories

    Directory of Open Access Journals (Sweden)

    Géraldine Jenvrin

    2008-04-01

    Full Text Available Le nouveau recueil de Mu/hammad ‘Abd al-Wakîl Jâzim témoigne d’une transformation capitale dans la littérature yéménite contemporaine :  le passage d’une forme expérimentale en rupture avec les règles de la nouvelle traditionnelle et avec la réalité yéménite, à une autre forme plus accomplie dans laquelle les principes traditionnels de la nouvelle sont ici associés sans complexe aux formes renouvelées du genre.  La nouvelle intitulée Le maître des vautours, présente, dans une structure narrative traditionnelle, un conte fantastique moderne qui mêle réalisme, symbolisme et poésie, et dans lequel l’auteur traite à sa manière les thèmes littéraires contemporains de la dualité du rêve et de la réalité, du désenchantement et de l’enfermement perpétuel.  C’est notamment en s’inspirant de la langue, des pratiques orales, des croyances et de l’imaginaire populaire, que l’auteur, soucieux de donner un ancrage au texte dans la réalité yéménite, transfigure cette expérience existentielle moderne.The latest collection of short stories by Mu/hammad 'Abd al-Wakîl signals a major shift in contemporary Yemeni literature: from an experimental form, breaking away from both traditional short story conventions and Yemeni reality, to another, more accomplished form, unabashedly mixing traditional short story principles with renewed genre forms. The short story entitled The Vulture Master presents us, from within a traditional narrative structure, with a modern fantasy tale blending in realism, symbolism and poetry, and where the writer deals in his own way with such contemporary literary themes as disenchantment, perpetual captivity, and the duality of dream and reality. Drawing his inspiration from language itself, oral practices, beliefs and popular imagery, the writer, seeking to set his tale firmly in Yemeni reality, manages to transfigure this modern existential experiment.

  13. Electron-excited molecule interactions

    International Nuclear Information System (INIS)

    Christophorou, L.G.; Tennessee Univ., Knoxville, TN

    1991-01-01

    In this paper the limited but significant knowledge to date on electron scattering from vibrationally/rotationally excited molecules and electron scattering from and electron impact ionization of electronically excited molecules is briefly summarized and discussed. The profound effects of the internal energy content of a molecule on its electron attachment properties are highlighted focusing in particular on electron attachment to vibrationally/rotationally and to electronically excited molecules. The limited knowledge to date on electron-excited molecule interactions clearly shows that the cross sections for certain electron-molecule collision processes can be very different from those involving ground state molecules. For example, optically enhanced electron attachment studies have shown that electron attachment to electronically excited molecules can occur with cross sections 10 6 to 10 7 times larger compared to ground state molecules. The study of electron-excited molecule interactions offers many experimental and theoretical challenges and opportunities and is both of fundamental and technological significance. 54 refs., 15 figs

  14. Organic Molecules in Meteorites

    Science.gov (United States)

    Martins, Zita

    2015-08-01

    Carbonaceous meteorites are primitive samples from the asteroid belt, containing 3-5wt% organic carbon. The exogenous delivery of organic matter by carbonaceous meteorites may have contributed to the organic inventory of the early Earth. The majority (>70%) of the meteoritic organic material consist of insoluble organic matter (IOM) [1]. The remaining meteoritic organic material (meteorites contain soluble organic molecules with different abundances and distributions, which may reflect the extension of aqueous alteration or thermal metamorphism on the meteorite parent bodies. Extensive aqueous alteration on the meteorite parent body may result on 1) the decomposition of α-amino acids [5, 6]; 2) synthesis of β- and γ-amino acids [2, 6-9]; 3) higher relative abundances of alkylated polycyclic aromatic hydrocarbons (PAHs) [6, 10]; and 4) higher L-enantiomer excess (Lee) value of isovaline [6, 11, 12].The soluble organic content of carbonaceous meteorites may also have a contribution from Fischer-Tropsch/Haber-Bosch type gas-grain reactions after the meteorite parent body cooled to lower temperatures [13, 14].The analysis of the abundances and distribution of the organic molecules present in meteorites helps to determine the physical and chemical conditions of the early solar system, and the prebiotic organic compounds available on the early Earth.[1] Cody and Alexander (2005) GCA 69, 1085. [2] Cronin and Chang (1993) in: The Chemistry of Life’s Origin. pp. 209-258. [3] Martins and Sephton (2009) in: Amino acids, peptides and proteins in organic chemistry. pp. 1-42. [4] Martins (2011) Elements 7, 35. [5] Botta et al. (2007) MAPS 42, 81. [6] Martins et al. (2015) MAPS, in press. [7] Cooper and Cronin (1995) GCA 59, 1003. [8] Glavin et al. (2006) MAPS. 41, 889. [9] Glavin et al. (2011) MAPS 45, 1948. [10] Elsila et al. (2005) GCA 5, 1349. [11] Glavin and Dworkin (2009) PNAS 106, 5487. [12] Pizzarello et al. (2003) GCA 67, 1589. [13] Chan et al. (2012) MAPS. 47, 1502

  15. Tunnelling of a molecule

    International Nuclear Information System (INIS)

    Jarvis, P.D.; Bulte, D.P.

    1998-01-01

    A quantum-mechanical description of tunnelling is presented for a one-dimensional system with internal oscillator degrees of freedom. The 'charged diatomic molecule' is frustrated on encountering a barrier potential by its centre of charge not being coincident with its centre of mass, resulting in transitions amongst internal states. In an adiabatic limit, the tunnelling of semiclassical coherent-like oscillator states is shown to exhibit the Hartman and Bueuttiker-Landauer times t H and t BL , with the time dependence of the coherent state parameter for the tunnelled state given by α(t) = α e -iω(t+Δt) , Δt = t H - it BL . A perturbation formalism is developed, whereby the exact transfer matrix can be expanded to any desired accuracy in a suitable limit. An 'intrinsic' time, based on the oscillator transition rate during tunnelling, transmission or reflection, is introduced. In simple situations the resulting intrinsic tunnelling time is shown to vanish to lowest order. In the general case a particular (nonzero) parametrisation is inferred, and its properties discussed in comparison with the literature on tunnelling times for both wavepackets and internal clocks. Copyright (1998) CSIRO Australia

  16. Single molecule tracking

    Science.gov (United States)

    Shera, E. Brooks

    1988-01-01

    A detection system is provided for identifying individual particles or molecules having characteristic emission in a flow train of the particles in a flow cell. A position sensitive sensor is located adjacent the flow cell in a position effective to detect the emissions from the particles within the flow cell and to assign spatial and temporal coordinates for the detected emissions. A computer is then enabled to predict spatial and temporal coordinates for the particle in the flow train as a function of a first detected emission. Comparison hardware or software then compares subsequent detected spatial and temporal coordinates with the predicted spatial and temporal coordinates to determine whether subsequently detected emissions originate from a particle in the train of particles. In one embodiment, the particles include fluorescent dyes which are excited to fluoresce a spectrum characteristic of the particular particle. Photones are emitted adjacent at least one microchannel plate sensor to enable spatial and temporal coordinates to be assigned. The effect of comparing detected coordinates with predicted coordinates is to define a moving sample volume which effectively precludes the effects of background emissions.

  17. Les nouvelles perspectives d'analyse spatiale des nuisances sonores. Le projet SIGAUR (Système d'Information Géographique et Acoustique URbaine

    Directory of Open Access Journals (Sweden)

    Erwan Quesseveur

    1999-06-01

    Full Text Available Ce rapport présente un projet de recherche sur l’intégration d’une couche d’information de nuisances acoustiques dans un système d’information géographique.Après un développement sur l’état de la pollution et des moyens aujourd’hui en vigueur pour la combattre, on va montrer les nouvelles perspectives offertes pour l’analyse spatiale du bruit. En confrontant cette nuisance aux enjeux du territoire, elle peut devenir un véritable critère de décision en aménagement du territoire.Ce projet résulte d’une collaboration entre le Centre Scientifique et Technique du Bâtiment C.S.T.B. et l’équipe " S.I.G. " de l'Institut de Géographie Alpine (IGA

  18. L'auteure mise en scène et mise à nu. Sur les fausses confessions de La nouvelle pornographie

    Directory of Open Access Journals (Sweden)

    Joëlle Papillon

    2010-11-01

    Full Text Available L'inclusion dans La nouvelle pornographie (2000 du nom propre de l'auteure est perçue comme une implication qui la met en danger. La métalepse est utilisée pour inscrire le roman dans la mouvance des confessions sexuelles et se jouer de leurs codes. Comme le discours publicitaire, Marie Nimier utilise la rhétorique pornographique afin de « vendre » un contenu domestique : la pornographie de surface dissimule un récit qui réinscrit l'amour comme moteur du désir féminin. Nimier joue de la métalepse pour déjouer les scènes pornographiques et séduire le lecteur par l'intelligence de ses manipulations plutôt que par ses dévoilements.

  19. Nouvelle méthodologie de synthèse de molécules à potentiel diurétique

    OpenAIRE

    Ouellet, Simon

    2007-01-01

    [Synthèse combinatoire ]. Le présent mémoire propose l'élaboration d'une nouvelle méthodologie de synthèse de molécules ayant un potentiel diurétique, et ciblant plus particulièrement les cotransporteurs cations-chlorures, responsables du mouvement couplé des ions sodium et/ou potassium avec celui du chlorure dans plusieurs types de cellules dont celles des néphrons. La première partie est consacrée à une description de la chimie combinatoire, aux travaux antérieurs effectués dans notre la...

  20. Développement des compétences interprofessionnelles de la nouvelle infirmière diplômée: revue de littérature

    OpenAIRE

    Meyer, Agnès,; Hauser, Christine,; Bulliard Verville, Danielle

    2017-01-01

    La pénurie infirmière qui touche actuellement la Suisse sera comblée en grande partie par les nouvelles diplômées infirmières1, d’ici quelques années. Cependant, un taux important de turnover dans les équipes peut mettre en péril leur encadrement. Leur processus d’insertion étant particulièrement éprouvant dans les premiers mois de pratique, il en résulte que nombre d’entre elles quittent précocement la profession. Comme stratégie pour pallier ce problème, la littérature montre les effets pos...

  1. Theoretical Investigations Regarding Single Molecules

    DEFF Research Database (Denmark)

    Pedersen, Kim Georg Lind

    Neoclassical Valence Bond Theory, Quantum Transport, Quantum Interference, Kondo Effect, and Electron Pumping. Trap a single organic molecule between two electrodes and apply a bias voltage across this "molecular junction". When electrons pass through the molecule, the different electron paths can...... interfere destructively or constructively. Destructive interference effects in electron transport could potentially improve thermo-electrics, organic logic circuits and energy harvesting. We have investigated destructive interference in off-resonant transport through organic molecules, and have found a set...

  2. A new class of medicament: radioactivity isotopes (1962); Une nouvelle classe de medicaments: les isotopes radioactifs (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    Very many radioelement are used in medicine, either for diagnosis or as therapeutics. The development of medicine has entailed an increase in the number of application of radioactive isotopes. Firstly used in the form of simple inorganic molecules for diagnosis or as anticancer therapeutics, radioelements are now used for labelling organic molecules, allowing functional specific studies of any kind of nature. Their production is made difficult by their radio-active properties. Their pharmaceutical properties, determined by tests and controls, depend either from radiochemistry and from medicine. The author reminds, in this report, the methods for the preparation and analysis, and set out the medical application. (author) [French] De tres nombreux radioelements trouvent une application en medecine humaine, soit dans le diagnostic, soit en therapeutique. L'evolution de la medecine entraine un accroissement du champ d'application des isotopes radioactifs. D'abord utilises sous forme de molecules minerales simples, pour les diagnostics ou des therapeutiques anticancereuses, les radioelements sont maintenant introduits dans des molecules organiques qui permettent des etudes fonctionnelles specifiques de toute nature. Leur fabrication est compliquee par leurs proprietes radioactives. Leurs caracteristiques pharmaceutiques determinees par des essais et controles, sont liees d'une part a la radiochimie, d'autre part a la medecine. L'auteur rappelle, dans cet expose, les methodes de preparation et d'analyse et aborde les applications medicales. (auteur)

  3. A new class of medicament: radioactivity isotopes (1962); Une nouvelle classe de medicaments: les isotopes radioactifs (1962)

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Y [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1962-07-01

    Very many radioelement are used in medicine, either for diagnosis or as therapeutics. The development of medicine has entailed an increase in the number of application of radioactive isotopes. Firstly used in the form of simple inorganic molecules for diagnosis or as anticancer therapeutics, radioelements are now used for labelling organic molecules, allowing functional specific studies of any kind of nature. Their production is made difficult by their radio-active properties. Their pharmaceutical properties, determined by tests and controls, depend either from radiochemistry and from medicine. The author reminds, in this report, the methods for the preparation and analysis, and set out the medical application. (author) [French] De tres nombreux radioelements trouvent une application en medecine humaine, soit dans le diagnostic, soit en therapeutique. L'evolution de la medecine entraine un accroissement du champ d'application des isotopes radioactifs. D'abord utilises sous forme de molecules minerales simples, pour les diagnostics ou des therapeutiques anticancereuses, les radioelements sont maintenant introduits dans des molecules organiques qui permettent des etudes fonctionnelles specifiques de toute nature. Leur fabrication est compliquee par leurs proprietes radioactives. Leurs caracteristiques pharmaceutiques determinees par des essais et controles, sont liees d'une part a la radiochimie, d'autre part a la medecine. L'auteur rappelle, dans cet expose, les methodes de preparation et d'analyse et aborde les applications medicales. (auteur)

  4. Biofuels: from microbes to molecules

    National Research Council Canada - National Science Library

    Lu, Xuefeng

    2014-01-01

    .... The production of different biofuel molecules including hydrogen, methane, ethanol, butanol, higher chain alcohols, isoprenoids and fatty acid derivatives, from genetically engineered microbes...

  5. Labelled molecules, modern research implements

    International Nuclear Information System (INIS)

    Pichat, L.; Langourieux, Y.

    1974-01-01

    Details of the synthesis of carbon 14- and tritium-labelled molecules are examined. Although the methods used are those of classical organic chemistry the preparation of carbon 14-labelled molecules differs in some respects, most noticeably in the use of 14 CO 2 which requires very special handling techniques. For the tritium labelling of organic molecules the methods are somewhat different, very often involving exchange reactions. The following are described in turn: the so-called Wilzbach exchange method; exchange by catalysis in solution; catalytic hydrogenation with tritium; reductions with borotritides. Some applications of labelled molecules in organic chemistry, biochemistry and pharmacology are listed [fr

  6. Les nouvelles formes de la communication autour des projets urbains : modalités, impacts, enjeux pour un débat participatif

    Directory of Open Access Journals (Sweden)

    Hélène Bailleul

    2008-09-01

    Full Text Available Dans cet article, nous observons les évolutions que l’usage des nouvelles technologies implique dans la communication autour des projets urbains. Notre analyse des nouvelles modalités qu’Internet a pu importer dans la participation des habitants aux projets urbains (partie 1 nous pousse à observer, plus spécifiquement, les modifications qui ont trait, dans ce contexte, à la nature et au statut de l’information sur l’espace. La démocratisation des techniques de représentation de l’espace par ordinateur (3D, simulation entraîne le recours quasi systématique à des images virtuelles du projet, d’une grande qualité (partie 2, mais dont on ne connaît que très peu les impacts sur la perception et la réception que les habitants font du projet (partie 3.In this article, we observe the evolutions involved by the use of new technology in the communication around urban projects. Our analysis of the new modalities, Internet was able to import in the participation of inhabitants in urban projects (chapter 1 urges us to examine, more specifically, the modifications concerning the nature and the status of the information about space. The democratization of computer-based spatial representation’s tools (3D, simulation entails more and more systematic recourse to virtual images of the project, with high definition (chapter 2. But, nowadays, we still know little about their impacts on the perception and the reception, the inhabitants make of the project (chapter 3.

  7. Growing interstellar molecules with ion-molecule reactions

    International Nuclear Information System (INIS)

    Bohme, D.K.

    1989-01-01

    Laboratory measurements of gas-phase ion-molecule reactions continue to provide important insights into the chemistry of molecular growth in interstellar environments. It is also true that the measurements are becoming more demanding as larger molecules capture our interest. While some of these measurements are motivated by current developments in chemical models of interstellar environments or by new molecular observations by astronomers, others explore novel chemistry which can lead to predictions of new interstellar molecules. Here the author views the results of some recent measurements, taken in the Ion Chemistry Laboratory at York University with the SIFT technique, which address some of the current needs of modellers and observers and which also provide some new fundamental insight into molecular growth, particularly when it occurs in the presence of large molecules such as PAH molecules which are now thought to have a major influence on the chemistry of interstellar environments in which they are present

  8. Enzyme Molecules in Solitary Confinement

    Directory of Open Access Journals (Sweden)

    Raphaela B. Liebherr

    2014-09-01

    Full Text Available Large arrays of homogeneous microwells each defining a femtoliter volume are a versatile platform for monitoring the substrate turnover of many individual enzyme molecules in parallel. The high degree of parallelization enables the analysis of a statistically representative enzyme population. Enclosing individual enzyme molecules in microwells does not require any surface immobilization step and enables the kinetic investigation of enzymes free in solution. This review describes various microwell array formats and explores their applications for the detection and investigation of single enzyme molecules. The development of new fabrication techniques and sensitive detection methods drives the field of single molecule enzymology. Here, we introduce recent progress in single enzyme molecule analysis in microwell arrays and discuss the challenges and opportunities.

  9. Organizing and addressing magnetic molecules.

    Science.gov (United States)

    Gatteschi, Dante; Cornia, Andrea; Mannini, Matteo; Sessoli, Roberta

    2009-04-20

    Magnetic molecules ranging from simple organic radicals to single-molecule magnets (SMMs) are intensively investigated for their potential applications in molecule-based information storage and processing. The goal of this Article is to review recent achievements in the organization of magnetic molecules on surfaces and in their individual probing and manipulation. We stress that the inherent fragility and redox sensitivity of most SMM complexes, combined with the noninnocent role played by the substrate, ask for a careful evaluation of the structural and electronic properties of deposited molecules going beyond routine methods for surface analysis. Detailed magnetic information can be directly obtained using X-ray magnetic circular dichroism or newly emerging scanning probe techniques with magnetic detection capabilities.

  10. Ion-Molecule Reaction Dynamics.

    Science.gov (United States)

    Meyer, Jennifer; Wester, Roland

    2017-05-05

    We review the recent advances in the investigation of the dynamics of ion-molecule reactions. During the past decade, the combination of single-collision experiments in crossed ion and neutral beams with the velocity map ion imaging detection technique has enabled a wealth of studies on ion-molecule reactions. These methods, in combination with chemical dynamics simulations, have uncovered new and unexpected reaction mechanisms, such as the roundabout mechanism and the subtle influence of the leaving group in anion-molecule nucleophilic substitution reactions. For this important class of reactions, as well as for many fundamental cation-molecule reactions, the information obtained with crossed-beam imaging is discussed. The first steps toward understanding micro-solvation of ion-molecule reaction dynamics are presented. We conclude with the presentation of several interesting directions for future research.

  11. Gestion par projets et risques pour la santé psychologique au travail dans la nouvelle économie

    Directory of Open Access Journals (Sweden)

    Marie-Josée Legault

    2006-05-01

    Full Text Available Y a-t-il des problèmes de santé mentale propres au travail dans la nouvelle économie ? Quoiqu’on puisse constater que le modèle de demande psychologique - autonomie décisionnelle de Karasek et Theorell- trouve aussi son application dans les milieux de travail qui empruntent cette forme, on observe, en fait, des formes particulières de ces facteurs dans la forme d’organisation du travail propre à la gestion par projets. Assimilables à « l’hypersollicitation par le client » comme il a été repéré par Christophe Dejours, ces formes ont été observées lors d’une enquête menée récemment sur la conciliation entre la vie privée et la vie professionnelle dans sept organisations montréalaises. La recherche qualitative a recueilli en tout le discours de 88 répondants distribués également selon le sexe et exerçant des fonctions liées au génie informatique. Ces observations permettent d’envisager une nuance au modèle théorique de la santé mentale ci-haut mentionné, visant à tenir compte des effets délétères d’une très grande latitude décisionnelle assortie de très grandes responsabilités chez des travailleurs hautement qualifiés.Are there distinct mental health problems among workers in the new economy? Although we may observe that the psychological demand - decision latitude model of Karakek and Theorell is appropriate and also finds its application in this type of workplace, we also notice some particular forms that these factors take in the management-by-project work organization model. Akin to the so-called "client’s hyper-demanding activity" as identified by Christophe Dejours, these forms were observed during a recent field study about balancing work and family in seven Montreal organizations. The qualitative study collected data from 88 individual interviews of information technology engineers, evenly distributed by gender. These observations allow a nuance of the above-mentioned theoretical

  12. Single Molecule Electronics and Devices

    Science.gov (United States)

    Tsutsui, Makusu; Taniguchi, Masateru

    2012-01-01

    The manufacture of integrated circuits with single-molecule building blocks is a goal of molecular electronics. While research in the past has been limited to bulk experiments on self-assembled monolayers, advances in technology have now enabled us to fabricate single-molecule junctions. This has led to significant progress in understanding electron transport in molecular systems at the single-molecule level and the concomitant emergence of new device concepts. Here, we review recent developments in this field. We summarize the methods currently used to form metal-molecule-metal structures and some single-molecule techniques essential for characterizing molecular junctions such as inelastic electron tunnelling spectroscopy. We then highlight several important achievements, including demonstration of single-molecule diodes, transistors, and switches that make use of electrical, photo, and mechanical stimulation to control the electron transport. We also discuss intriguing issues to be addressed further in the future such as heat and thermoelectric transport in an individual molecule. PMID:22969345

  13. Une voix dans un chœur risque de n’être point entendue. André Gide et La Nouvelle Revue française, 1908-1914

    NARCIS (Netherlands)

    Koffeman, M.N.; Wittmann, Jean-Michel

    2017-01-01

    Cet article étudie la tension entre l’individualisme gidien et la collectivité littéraire que forme la première Nouvelle revue française. Entreprise commune par excellence, la revue gagne à être considérée dans son ensemble. Une lecture des sommaires de la NRF relativise le rôle de Gide et met en

  14. Spin tunneling in magnetic molecules

    Science.gov (United States)

    Kececioglu, Ersin

    In this thesis, we will focus on spin tunneling in a family of systems called magnetic molecules such as Fe8 and Mn12. This is comparatively new, in relation to other tunneling problems. Many issues are not completely solved and/or understood yet. The magnetic molecule Fe 8 has been observed to have a rich pattern of degeneracies in its magnetic spectrum. We focus on these degeneracies from several points of view. We start with the simplest anisotropy Hamiltonian to describe the Fe 8 molecule and extend our discussion to include higher order anisotropy terms. We give analytical expressions as much as we can, for the degeneracies in the semi-classical limit in both cases. We reintroduce jump instantons to the instanton formalism. Finally, we discuss the effect of the environment on the molecule. Our results, for all different models and techniques, agree well with both experimental and numerical results.

  15. Experimental decoherence in molecule interferometry

    International Nuclear Information System (INIS)

    Hackermueller, L.; Hornberger, K.; Stibor, A.; Zeilinger, A.; Arndt, M.; Kiesewetter, G.

    2005-01-01

    Full text: We present three mechanisms of decoherence that occur quite naturally in matter wave interferometer with large molecules. One way molecules can lose coherence is through collision with background gas particles. We observe a loss of contrast with increasing background pressure for various types of gases. We can understand this phenomenon quantitatively with a new model for collisional decoherence which corrects older models by a factor of 2 π;. The second experiment studies the thermal emission of photons related to the high internal energy of the interfering molecules. When sufficiently many or sufficiently short photons are emitted inside the interferometer, the fringe contrast is lost. We can continuously vary the temperature of the molecules and compare the loss of contrast with a model based on decoherence theory. Again we find good quantitative agreement. A third mechanism that influences our interference pattern is dephasing due to vibrations of the interference gratings. By adding additional vibrations we study this effect in more detail. (author)

  16. Photoionization of atoms and molecules

    International Nuclear Information System (INIS)

    Samson, J.A.R.

    1976-01-01

    A literature review on the present state of knowledge in photoionization is presented. Various experimental techniques that have been developed to study photoionization, such as fluorescence and photoelectron spectroscopy, mass spectroscopy, are examined. Various atoms and molecules were chosen to illustrate these techniques, specifically helium and xenon atoms and hydrogen molecules. Specialized photoionization such as in positive and negative ions, excited states, and free radicals is also treated. Absorption cross sections and ionization potentials are also discussed

  17. Low pressure tritiation of molecules

    International Nuclear Information System (INIS)

    Moran, T.F.; Powers, J.C.; Lively, M.O.

    1980-01-01

    A method is described of tritiating sensitive biological molecules by depositing molecules of the substance to be tritiated on a supporting substrate in an evacuated vacuum chamber near, but not in the path of, an electron beam which traverses the chamber, admitting tritium gas into the chamber, and subjecting the tritium to the electron beam. Vibrationally excited tritium gas species are generated which collide and react with the substance thus incorporating tritium atoms into the substance. (U.K.)

  18. Print Culture and the New Maritime Frontier in Rangoon and Penang Culture de l’imprimé et nouvelle frontière maritime à Rangoon et Penang

    Directory of Open Access Journals (Sweden)

    Su Lin Lewis

    2012-10-01

    Full Text Available From the mid-19th century, vast improvements in steamship and communication technology created an interlinked network of port-cities in the Indian Ocean and maritime Asia. Though Rangoon and Penang had starkly different relationships to colonial rule, they shared a lineage as multi-ethnic ports where various communities had existed side-by-side for centuries. The advent of the Victorian era fostered new class and racial divisions between them, yet also created a new feuilleton culture in the port-city with the mushrooming of newspapers, books, and a new reading public. Diverse ethnic and linguistic communities sought platforms to articulate their concerns and inform themselves of the affairs of the world, and their place within it. Burmese in Rangoon, imbued with a renewed sense of cultural pride, absorbed the rising tide of anticolonialism nationalism echoing throughout the world. Penangites transformed their society using the liberal, cosmopolitan tenants of imperial citizenship to make political and cultural claims for a multi-ethnic society. The vibrant, outward-looking atmosphere of the colonial port-city as a node of information and cultural exchange made Penang and Rangoon the intellectual staging grounds for new visions of the nation.À compter du milieu du xixe siècle, d’importantes améliorations dans la navigation à vapeur et les technologies des communications ont créé un réseau de villes portuaires dans l’Océan indien et l’Asie maritime. Même si Rangoon et Penang avaient des relations divergentes avec la puissance coloniale, elles participaient d’un type identique comme ports où cohabitaient depuis des siècles des communautés d’ethnies différentes. L’ère victorienne conduisit à de nouvelles divisions sociales et ethniques, mais suscita dans la ville portuaire une nouvelle culture littéraire avec le foisonnement des journaux, des livres et un nouveau lectorat. Les communautés ethniques et linguistiques

  19. Le programme ARTEMIS : nouvel outil pour la datation radiocarbone AMS (Spectromètre de Masse par Accélérateur et nouvelles problématiques

    Directory of Open Access Journals (Sweden)

    Cyrille Billard

    2012-04-01

    Full Text Available La mise en route du nouvel équipement ARTEMIS (Accélérateur pour la Recherche en sciences de la Terre, Environnement, Muséologie, Implanté à Saclay à partir de 2004 ouvre de nouvelles perspectives scientifiques et conduit à de nouvelles procédures de soumission des échantillons destinés à une datation 14C. Le MCC dispose aujourd’hui de droits alloués aux services régionaux de l'archéologie, services du ministère de la Culture, confrontés à ce type de demandes (musées, monuments historiques. Il impose désormais une nouvelle démarche de programmation scientifique des datations, associant une analyse critique des demandes.Since 2004, the availability at Saclay of a new ARTEMIS installation (Accélérateur pour la Recherche en sciences de la Terre, Environnement, Muséologie has opened new scientific perspectives and led to new procedures for submitting samples for carbon-14 dating. The French Ministry of Culture has the possibility of using this tool for radiocarbon dating at the request of its regional archaeological services or other services, such as museums and the historic monuments administration. This use now implies a new approach to the scientific planning for dating problems, associated with a critical analysis of the requests.

  20. Thermal ion-molecule reactions in oxygen-containing molecules

    International Nuclear Information System (INIS)

    Kumakura, Minoru

    1981-02-01

    The energetics of ions and the thermal ion-molecule reactions in oxygen-containing molecules have been studied with a modified time-of-flight mass spectrometer. It was found that the translational energy of ion can be easily obtained from analysis of the decay curve using the time-of-flight mass spectrometer. The condensation-elimination reactions proceeded via cross- and homo-elimination mechanism in which the nature of intermediate-complex could be correlated with the nature of reactant ion. It was elucidated that behavior of poly-atomic oxygen-containing ions on the condensation-elimination reactions is considerably influenced by their oxonium ion structures having functional groups. In addition, the rate constants of the condensation-elimination reactions have affected with the energy state of reactant ion and the dipole moment and/or the polarizability of neutral molecule. It was clarified that the rate constants of the ion-molecule clustering reactions in poly-atomic oxygen-containing molecules such as cyclic ether of six member rings are very large and the cluster ions are stable owing to the large number of vibrational degree of freedom in the cluster ions. (author)

  1. Relation de service, rapport social de service : Quelle grille d’analyse ? Analysing service relationships and service-based social relationships. Debate with the editors of the Nouvelle Revue du Travail Relación de servicio, vínculo social de servicio: ¿qué modelo analítico? Debate con la redacción de la Nouvelle Revue du Travail

    Directory of Open Access Journals (Sweden)

    Guillaume Tiffon

    2013-03-01

    Full Text Available Dans un échange avec la Nouvelle Revue du Travail, Pascal Ughetto et Philippe Zarifian prolongent la controverse sur les grilles d’analyse des services, en discutant les pré-requis sur lesquels reposent leurs postures respectives. Ce débat fait suite à leurs contributions dans le dossier Controverses de ce numéro « Relation de service, rapport social de service. Quelle grille d’analyse ? »In a conversation with the Nouvelle Revue du Travail, Pascal Ughetto and Philippe Zarifian address the controversy about service-related analytical grids, by focusing on the preconditions underlying each grid’s particular orientation. The debate follows their contributions to the Controverses special section found in a special issue called “Analysing service relationships and service-based social relationships”En una conversación con la Nouvelle Revue du Travail, Pascal Ughetto y Philippe Zarifian prolongan la controversia sobre los modelos analíticos de los servicios, debatiendo sobre los prerrequisitos en los cuales se apoyan sus respectivas posturas. Ese debate ha surgido tras sus contribuciones al número especial Controverses de esta edición “Relación de servicio, vínculo social de servicio. ¿Qué modelo analítico ?

  2. The Molecule Cloud - compact visualization of large collections of molecules

    Directory of Open Access Journals (Sweden)

    Ertl Peter

    2012-07-01

    Full Text Available Abstract Background Analysis and visualization of large collections of molecules is one of the most frequent challenges cheminformatics experts in pharmaceutical industry are facing. Various sophisticated methods are available to perform this task, including clustering, dimensionality reduction or scaffold frequency analysis. In any case, however, viewing and analyzing large tables with molecular structures is necessary. We present a new visualization technique, providing basic information about the composition of molecular data sets at a single glance. Summary A method is presented here allowing visual representation of the most common structural features of chemical databases in a form of a cloud diagram. The frequency of molecules containing particular substructure is indicated by the size of respective structural image. The method is useful to quickly perceive the most prominent structural features present in the data set. This approach was inspired by popular word cloud diagrams that are used to visualize textual information in a compact form. Therefore we call this approach “Molecule Cloud”. The method also supports visualization of additional information, for example biological activity of molecules containing this scaffold or the protein target class typical for particular scaffolds, by color coding. Detailed description of the algorithm is provided, allowing easy implementation of the method by any cheminformatics toolkit. The layout algorithm is available as open source Java code. Conclusions Visualization of large molecular data sets using the Molecule Cloud approach allows scientists to get information about the composition of molecular databases and their most frequent structural features easily. The method may be used in the areas where analysis of large molecular collections is needed, for example processing of high throughput screening results, virtual screening or compound purchasing. Several example visualizations of large

  3. Molecule-by-Molecule Writing Using a Focused Electron Beam

    DEFF Research Database (Denmark)

    Van Dorp, Willem F.; Zhang, Xiaoyan; Feringa, Ben L.

    2012-01-01

    atoms also be written with an electron beam? We verify this with focused electron-beam-induced deposition (FEBID), a direct-write technique that has the current record for the smallest feature written by (electron) optical lithography. We show that the deposition of an organometallic precursor...... on graphene can be followed molecule-by-molecule with FEBID. The results show that mechanisms that are inherent to the process inhibit a further increase in control over the process. Hence, our results present the resolution limit of (electron) optical lithography techniques. The writing of isolated...

  4. Physics of Complex Polymeric Molecules

    Science.gov (United States)

    Kelly, Joshua Walter

    The statistical physics of complex polymers with branches and circuits is the topic of this dissertation. An important motivation are large, single-stranded (ss) RNA molecules. Such molecules form complex ``secondary" and ``tertiary" structures that can be represented as branched polymers with circuits. Such structures are in part directly determined by the nucleotide sequence and in part subject to thermal fluctuations. The polymer physics literature on molecules in this class has mostly focused on randomly branched polymers without circuits while there has been minimal research on polymers with specific structures and on polymers that contain circuits. The dissertation is composed of three parts: Part I studies branched polymers with thermally fluctuating structure confined to a potential well as a simple model for the encapsidation of viral RNA. Excluded volume interactions were ignored. In Part II, I apply Flory theory to the study of the encapsidation of viral ss RNA molecules with specific branched structures, but without circuits, in the presence of excluded volume interaction. In Part III, I expand on Part II and consider complex polymers with specific structure including both branching and circuits. I introduce a method based on the mathematics of Laplacian matrices that allows me to calculate density profiles for such molecules, which was not possible within Flory theory.

  5. Quantum transport through organic molecules

    International Nuclear Information System (INIS)

    Maiti, Santanu K.

    2007-01-01

    We investigate the electronic transport for the model of benzene-1, 4-dithiolate (BDT) molecule and some other geometric models of benzene molecule attached with two semi-infinite metallic electrodes by the use of Green's function technique. An analytic approach for the electronic transport through the molecular bridges is presented, based on the tight-binding model. Transport of electrons in such molecular bridges is strongly affected by the geometry of the molecules and their coupling strength with the electrodes. Conductance (g) shows resonance peaks associated with the molecular energy eigenstates. In the weak molecule-to-electrodes coupling limit current (I) passing through the molecules shows staircase-like behavior with sharp steps, while, it varies quite continuously in the limit of strong molecular coupling with the applied bias voltage (V). In presence of the transverse magnetic field conductance gives oscillatory behavior with flux φ, threaded by the molecular ring, showing φ 0 ( = ch/e) flux-quantum periodicity. Though conductance changes with the application of transverse magnetic field, but the current-voltage characteristics remain same in presence of this magnetic field for these molecular bridge systems

  6. O inventário das curiosidades botânicas da Nouvelle France de Pierre-François-Xavier de Charlevoix (1744 The inventory of botanical curiosities in Pierre-François-Xavier de Charlevoix's Nouvelle France (1744

    Directory of Open Access Journals (Sweden)

    Michel Kobelinski

    2013-03-01

    Full Text Available Verifica a extensão dos aportes botânicos de Pierre-François-Xavier de Charlevoix em Histoire et description générale de la Nouvelle France em relação a trabalhos de pesquisadores anteriores, suas valorações das representações iconográficas e discursivas e aplicabilidade no projeto de colonização francesa. Investiga-se o que o levou a preterir o modelo taxionômico de Lineu e o que pretendia com seu catálogo de curiosidades botânicas. O desenlace de sua trajetória filosófico-religiosa permite compreender seu posicionamento no quadro de classificação da natureza, os sentidos das informações etnológicas, as formas de apropriação intelectual e os usos da iconografia botânica e do discurso como propaganda político-emotiva para incentivar a ocupação colonial.The article explores the botanical contributions of Pierre-François-Xavier de Charlevoix's book Histoire et description générale de la Nouvelle France vis-à-vis the contributions of previous researchers, his use of iconographic and discursive representations and its relevance to the project of French colonization. It investigates why he refused Linnaeus' taxonomic model and what he intended with his catalogue of botanical curiosities. The unfolding of his philosophical and religious trajectory allows to understand his stance regarding the classification of nature, the meanings of ethnological information, his forms of intellectual appropriation, and his use of discourse and botanical iconography as political and emotional propaganda to encourage colonial settlement.

  7. Dissociation and decay of ultracold sodium molecules

    International Nuclear Information System (INIS)

    Mukaiyama, T.; Abo-Shaeer, J.R.; Xu, K.; Chin, J.K.; Ketterle, W.

    2004-01-01

    The dissociation of ultracold molecules was studied by ramping an external magnetic field through a Feshbach resonance. The observed dissociation energies directly yielded the strength of the atom-molecule coupling. They showed nonlinear dependence on the ramp speed. This was explained by a Wigner threshold law which predicts that the decay rate of the molecules above threshold increases with the density of states. In addition, inelastic molecule-molecule and molecule-atom collisions were characterized

  8. IMPACT DE L’ORIENTATION SUR LE CONFORT THERMIQUE INTERIEUR DANS L’HABITATION COLLECTIVE : Cas de la nouvelle ville Ali Mendjeli, Constantine

    Directory of Open Access Journals (Sweden)

    S BELLARA LOUAFI

    2009-06-01

    Une étude est effectuée sur le site de la nouvelle ville ALI MENDJELI de Constantine afin de comparer et de chercher la relation entre les éléments du climat et l’orientation. Une investigation sur terrain (relevé des températures, humidité relatives, températures de surfaces est entreprise pour évaluer la réponse quantitative globale pour ce type de climat (semi aride. Parallèlement à cela une simulation à l’aide d’un logiciel TRNSYS (version 14.1 a été effectuée pour tester plusieurs possibilités d’orientations et d’améliorations afin de déterminer les éléments qui peuvent servir à des conditions meilleures. Les résultats montrent que la prise en compte du critère orientation fait participer le bâtiment à une conception plus performante thermiquement et plus économe énergétiquement.

  9. A new method for dosing uranium in biological media; Nouvelle methode de dosage de l'uranium dans les milieux biologiques

    Energy Technology Data Exchange (ETDEWEB)

    Henry, Ph; Kobisch, Ch [Commissariat a l' Energie Atomique, Centre de Production de Plutonium, Marcoule (France). Centre d' Etudes Nucleaires

    1964-07-01

    This report describes a new method for dosing uranium in biological media based on measurement of alpha activity. After treatment of the sample with a mineral acid, the uranium is reduced to the valency four by trivalent titanium and is precipitated as phosphate in acid solution. The uranium is then separated from the titanium by precipitation as UF{sub 4} with lanthanum as carrier. A slight modification, unnecessary in the case of routine analyses, makes it possible to eliminate other possible alpha emitters (thorium and transuranic elements). (authors) [French] Ce rapport decrit une nouvelle methode de dosage de l'uranium dans les milieux biologiques par mesure de l'activite alpha. Apres mineralisation de l'echantillon, l'uranium est reduit a la valence IV par le titane trivalent et precipite en milieu acide sous forme de phosphate. L'uranium est ensuite separe du titane par precipitation a l'etat d'UF{sub 4} avec du lanthane entraineur. Une legere modification, inutile dans le cas d'analyses de routine, permet d'effectuer l'elimination d'autres emetteurs alpha eventuels (thorium et transuraniens). (auteurs)

  10. La catalyse d'épuration des gaz d'échappement automobiles. Situation actuelle et nouvelles orientations Catalytic Automotive Exhaust Gas Depollution. Present Status and New Trends

    Directory of Open Access Journals (Sweden)

    Prigent M.

    2006-11-01

    Full Text Available Cet article passe en revue les différents systèmes catalytiques de post-traitement utilisés actuellement sur la plupart des automobiles pour limiter leurs rejets de polluants. Les systèmes sont différenciés par leur mode de fonctionnement, le type de moteur à dépolluer (deux-temps, quatre-temps, diesel ou essence ou par leur mode de réalisation. Les nouvelles orientations, prévues pour respecter les futures réglementations antipollution, sont également décrites. On montre que certains véhicules prototypes, équipés de moteurs à combustion interne, sont capables d'avoir des émissions très proches de zéro tout comme les véhicules électriques. A review is made of the various types of exhaust gas aftertreatment systems presently used on most vehicles to reduce pollutant emissions. The systems are differentiated by their mode of action, according to the engine type to be depolluted (two-stroke, four-stroke, diesel or spark-ignition, and by their type of make-up. The major developments foreseen in the future, in view of compliance with the new legislations, are described. It is shown that some prototype vehicles with internal combustion engines are able to emit pollutant quantities really close to zero, such as electric cars.

  11. Small molecule fluoride toxicity agonists.

    Science.gov (United States)

    Nelson, James W; Plummer, Mark S; Blount, Kenneth F; Ames, Tyler D; Breaker, Ronald R

    2015-04-23

    Fluoride is a ubiquitous anion that inhibits a wide variety of metabolic processes. Here, we report the identification of a series of compounds that enhance fluoride toxicity in Escherichia coli and Streptococcus mutans. These molecules were isolated by using a high-throughput screen (HTS) for compounds that increase intracellular fluoride levels as determined via a fluoride riboswitch reporter fusion construct. A series of derivatives were synthesized to examine structure-activity relationships, leading to the identification of compounds with improved activity. Thus, we demonstrate that small molecule fluoride toxicity agonists can be identified by HTS from existing chemical libraries by exploiting a natural fluoride riboswitch. In addition, our findings suggest that some molecules might be further optimized to function as binary antibacterial agents when combined with fluoride. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Double photoionisation spectra of molecules

    CERN Document Server

    Eland, John

    2017-01-01

    This book contains spectra of the doubly charged positive ions (dications) of some 75 molecules, including the major constituents of terrestrial and planetary atmospheres and prototypes of major chemical groups. It is intended to be a new resource for research in all areas of molecular spectroscopy involving high energy environments, both terrestrial and extra-terrestrial. All the spectra have been produced by photoionisation using laboratory lamps or synchrotron radiation and have been measured using the magnetic bottle time-of-flight technique by coincidence detection of correlated electron pairs. Full references to published work on the same species are given, though for several molecules these are the first published spectra. Double ionisation energies are listed and discussed in relation to the molecular electronic structure of the molecules. A full introduction to the field of molecular double ionisation is included and the mechanisms by which double photoionisation can occur are examined in detail. A p...

  13. Technetium-aspirin molecule complexes

    International Nuclear Information System (INIS)

    El-Shahawy, A.S.; Mahfouz, R.M.; Aly, A.A.M.; El-Zohry, M.

    1993-01-01

    Technetium-aspirin and technetium-aspirin-like molecule complexes were prepared. The structure of N-acetylanthranilic acid (NAA) has been decided through CNDO calculations. The ionization potential and electron affinity of the NAA molecule as well as the charge densities were calculated. The electronic absorption spectra of Tc(V)-Asp and Tc(V)-ATS complexes have two characteristic absorption bands at 450 and 600 nm, but the Tc(V)-NAA spectrum has one characteristic band at 450 nm. As a comparative study, Mo-ATS complex was prepared and its electronic absorption spectrum is comparable with the Tc-ATS complex spectrum. (author)

  14. Teaching lasers to control molecules

    International Nuclear Information System (INIS)

    Judson, R.S.; Rabitz, H.

    1992-01-01

    We simulate a method to teach a laser pulse sequences to excite specified molecular states. We use a learning procedure to direct the production of pulses based on ''fitness'' information provided by a laboratory measurement device. Over a series of pulses the algorithm learns an optimal sequence. The experimental apparatus, which consists of a laser, a sample of molecules and a measurement device, acts as an analog computer that solves Schroedinger's equation n/Iexactly, in real time. We simulate an apparatus that learns to excite specified rotational states in a diatomic molecule

  15. Exotic helium molecules; Molecules exotiques d'helium

    Energy Technology Data Exchange (ETDEWEB)

    Portier, M

    2007-12-15

    We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}P{sub 0}) molecule, or a {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 {+-} 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime {tau} = (1.4 {+-} 0.3) {mu}s is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

  16. Exotic helium molecules; Molecules exotiques d'helium

    Energy Technology Data Exchange (ETDEWEB)

    Portier, M

    2007-12-15

    We study the photo-association of an ultracold cloud of magnetically trapped helium atoms: pairs of colliding atoms interact with one or two laser fields to produce a purely long range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}P{sub 0}) molecule, or a {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) long range molecule. Light shifts in one photon photo-association spectra are measured and studied as a function of the laser polarization and intensity, and the vibrational state of the excited molecule. They result from the light-induced coupling between the excited molecule, and bound and scattering states of the interaction between two metastable atoms. Their analysis leads to the determination of the scattering length a = (7.2 {+-} 0.6) ruling collisions between spin polarized atoms. The two photon photo-association spectra show evidence of the production of polarized, long-range {sup 4}He{sub 2}(2{sup 3}S{sub 1}-2{sup 3}S{sub 1}) molecules. They are said to be exotic as they are made of two metastable atoms, each one carrying a enough energy to ionize the other. The corresponding lineshapes are calculated and decomposed in sums and products of Breit-Wigner and Fano profiles associated to one and two photon processes. The experimental spectra are fit, and an intrinsic lifetime {tau} = (1.4 {+-} 0.3) {mu}s is deduced. It is checked whether this lifetime could be limited by spin-dipole induced Penning autoionization. This interpretation requires that there is a quasi-bound state close to the dissociation threshold in the singlet interaction potential between metastable helium atoms for the theory to match the experiment. (author)

  17. Nucleic Acids as Information Molecules.

    Science.gov (United States)

    McInerney, Joseph D.

    1996-01-01

    Presents an activity that aims at enabling students to recognize that DNA and RNA are information molecules whose function is to store, copy, and make available the information in biological systems, without feeling overwhelmed by the specialized vocabulary and the minutia of the central dogma. (JRH)

  18. Small Molecule PET-Radiopharmaceuticals

    NARCIS (Netherlands)

    Elsinga, Philip H.; Dierckx, Rudi A. J. O.

    This review describes several aspects required for the development of small molecule PET-tracers. Design and selection criteria are important to consider before starting to develop novel PET-tracers. Principles and latest trends in C-11 and F-18-radiochemistry are summarized. In addition an update

  19. Hybrid molecule/superconductor assemblies

    International Nuclear Information System (INIS)

    McDevitt, J.T.; Haupt, S.G.; Riley, D.R.; Zhao, J.; Zhou, J.P., Jones, C.

    1993-01-01

    The fabrication of electronic devices from molecular materials has attracted much attention recently. Schottky diodes, molecular transistors, metal-insulator-semiconductor diodes, MIS field effect transistors and light emitting diodes have all been prepared utilizing such substances. The active elements in these devices have been constructed by depositing the molecular phase onto the surface of a metal, semiconductor or insulating substrate. With the recent discovery of high temperature superconductivity, new opportunities now exist for the study of molecule/superconductor interactions as well as for the construction of novel hybrid molecule/superconductor devices. In this paper, methods for preparing the initial two composite molecule/semiconductor devices will be reported. Consequently, light sensors based on dye-coated superconductor junctions as well as molecular switches fashioned from conductive polymer coated superconductor junctions as well as molecular switches fashioned from conductive polymer coated superconductor microbridges will be discussed. Moreover, molecule/superconductor energy and electron transfer phenomena will be illustrated also for the first time

  20. Mass spectrometry of large molecules

    International Nuclear Information System (INIS)

    Facchetti, S.

    1985-01-01

    The lectures in this volume were given at a course on mass spectrometry of large molecules, organized within the framework of the Training and Education programme of the Joint Research Centre of the European Communities. Although first presented in 1983, most of the lectures have since been updated by their authors. (orig.)

  1. WHAT ARE THE MOLECULES DOING?

    African Journals Online (AJOL)

    Temechegn

    University of the Witwatersrand, Johannesburg, South Africa ... [African Journal of Chemical Education—AJCE 6(2), July 2016] ... understand science concepts: in essence these are macroscopic (phenomena), microscopic .... than the simple freeing up of already-existing smaller molecules: this implies a high melting point.

  2. Fascinating Organic Molecules from Nature

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 5. Fascinating Organic Molecules from Nature - Using a Natural ... Road Banashankari 2nd Stage Bangalore 560 070, India. Department of Chemistry Sri Sathya Sai Institute of Higher Learning Brindavan Campus Bangalore 560 067, India.

  3. Fascinating Organic Molecules from Nature

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 18; Issue 7. Fascinating Organic Molecules from Nature - Sweet Stimulants of ... Road Banashankari 2nd Stage Bangalore 560 070, India. Department of Chemistry Sri Sathya Sai Institute of Higher Learning Brindavan Campus Bangalore 560 067, India.

  4. Multiphoton dissociation of polyatomic molecules

    International Nuclear Information System (INIS)

    Schulz, P.A.

    1979-10-01

    The dynamics of infrared multiphoton excitation and dissociation of SF 6 was investigated under collision free conditions by a crossed laser-molecular beam method. In order to understand the excitation mechanism and to elucidate the requirements of laser intensity and energy fluence, a series of experiments were carried out to measure the dissociation yield dependences on energy fluence, vibrational temperature of SF 6 , the pulse duration of the CO 2 laser and the frequency in both one and two laser experiments. Translational energy distributions of the SF 5 dissociation product measured by time of flight and angular distributions and the dissociation lifetime of excited SF 6 as inferred from the observation of secondary dissociation of SF 5 into SF 4 and F during the laser pulse suggest that the dynamics of dissociation of excited molecules is dominated by complete energy randomization and rapid intramolecular energy transfer on a nanosecond timescale, and can be adequately described by RRKM theory. An improved phenomenological model including the initial intensity dependent excitation, a rate equation describing the absorption and stimulated emission of single photons, and the unimolecular dissociation of excited molecules is constructed based on available experimental results. The model shows that the energy fluence of the laser determines the excitation of molecules in the quasi-continuum and the excess energy with which molecules dissociate after the laser pulse. The role played by the laser intensity in multiphoton dissociation is more significant than just that of overcoming the intensity dependent absorption in the lowest levels. 63 references

  5. Isotope separation using vibrationally excited molecules

    International Nuclear Information System (INIS)

    Woodroffe, J.A.; Keck, J.C.

    1979-01-01

    Vibrational excitation of molecules having components of a selected isotope type is used to produce a conversion from vibrational to translational excitation of the molecules by collision with the molecules of a heavy carrier gas. The resulting difference in translaton between the molecules of the selected isotope type and all other molecules of the same compound permits their separate collection. When applied to uranium enrichment, a subsonic cryogenic flow of molecules of uranium hexafluoride in combination with an argon carrier gas is directed through a cooled chamber that is illuminated by laser radiaton tuned to vibrationally excite the uranium hexafluoride molecules of a specific uranium isotope. The excited molecules collide with carrier gas molecules, causing a conversion of the excitation energy into a translation of the excited molecule, which results in a higher thermal energy or diffusivity than that of the other uranium hexafluoride molecules. The flowing molecules including the excited molecules directly enter a set of cryogenically cooled channels. The higher thermal velocity of the excited molecules increases the probability of their striking a collector surface. The molecules which strike this surface immediately condense. After a predetermined thickness of molecules is collected on the surface, the flow of uranium hexafluoride is interrupted and the chamber heated to the point of vaporization of the collected hexafluoride, permitting its removal. (LL)

  6. Preparation of translationally cold neutral molecules.

    Science.gov (United States)

    Di Domenicantonio, Giulia; Bertsche, Benjamin; Osterwalder, Andreas

    2011-01-01

    Efforts at EPFL to obtain translationally cold neutral molecules are described. Active deceleration of polar molecules is performed by confining the molecules in moving three-dimensional electrostatic traps, and by appropriately choosing the velocity of those traps. Alternatively, cold molecules can be obtained by velocity filtering. Here, the velocity of the molecules is not changed, but instead the cold molecules are extracted from a thermal sample by using the competition between the electrostatic force and the centrifugal force inside a bent electrostatic guide for polar molecules.

  7. Observing electron motion in molecules

    International Nuclear Information System (INIS)

    Chelkowski, S; Yudin, G L; Bandrauk, A D

    2006-01-01

    We study analytically the possibility for monitoring electron motion in a molecule using two ultrashort laser pulses. The first prepares a coherent superposition of two electronic molecular states whereas the second (attosecond pulse) photoionizes the molecule. We show that interesting information about electron dynamics can be obtained from measurement of the photoelectron spectra as a function of the time delay between two pulses. In particular, asymmetries in photoelectron angular distribution provide a simple signature of the electron motion within the initial time-dependent coherently coupled two molecular states. Both asymmetries and electron spectra show very strong two-centre interference patterns. We illustrate these effects using as an example a dissociating hydrogen molecular ion probed by the attosecond pulses

  8. Tunneling Ionization of Diatomic Molecules

    DEFF Research Database (Denmark)

    Svensmark, Jens Søren Sieg

    2016-01-01

    When a molecule is subject to a strong laser field, there is a probability that an electron can escape, even though the electrons are bound by a large potential barrier. This is possible because electrons are quantum mechanical in nature, and they are therefore able to tunnel through potential...... barriers, an ability classical particles do not possess. Tunnelling is a fundamental quantum mechanical process, a process that is distinctly non-classical, so solving this tunnelling problem is not only relevant for molecular physics, but also for quantum theory in general. In this dissertation the theory...... of tunneling ionizaion of molecules is presented and the results of numerical calculations are shown. One perhaps surprising result is, that the frequently used Born-Oppenheimer approximation breaks down for weak fields when describing tunneling ionization. An analytic theory applicable in the weak-field limit...

  9. Physics of atoms and molecules

    International Nuclear Information System (INIS)

    Bransden, B.H.; Joachain, C.J.

    1983-01-01

    This book presents a unified account of the physics of atoms and molecules at a level suitable for second- and third-year undergraduate students of physics and physical chemistry. Following a brief historical introduction to the subject the authors outline the ideas and approximation methods of quantum mechanics to be used later in the book. Six chapters look at the structure of atoms and the interactions between atoms and electromagnetic radiation. The authors then move on to describe the structure of molecules and molecular spectra. Three chapters deal with atomic collisions, the scattering of electrons by atoms and the scattering of atoms by atoms. The concluding chapter considers a few of the many important applications of atomic physics within astrophysics, laser technology, and nuclear fusion. Problems are given at the end of each chapter, with hints at the solutions in an appendix. Other appendices include various special topics and derivations together with useful tables of units. (author)

  10. Electrondriven processes in polyatomic molecules

    Energy Technology Data Exchange (ETDEWEB)

    McKoy, Vincent [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2017-03-20

    This project developed and applied scalable computational methods to obtain information about low-energy electron collisions with larger polyatomic molecules. Such collisions are important in modeling radiation damage to living systems, in spark ignition and combustion, and in plasma processing of materials. The focus of the project was to develop efficient methods that could be used to obtain both fundamental scientific insights and data of practical value to applications.

  11. Intersystem crossing in complex molecules

    International Nuclear Information System (INIS)

    Pappalardo, R.G.

    1980-01-01

    The general question of singlet-triplet intersystem crossing is addressed in the context of large organic molecules, i.e., ''complex'' molecules capable of self-relaxation in the absence of collisions. Examples of spectral properties of such molecules in the vapor phase are discussed, relying on extensive Russian literature in this area. Formal expressions for the relaxation rate in the electronic excited states are derived on the basis of the formalism of collision theory, and are applied to the specific case of intersystem crossing. The derivation of the ''energy-gap'' law for triplet-singlet conversion in aromatic hydrocarbons is briefly outlined. The steep rise of internal conversion rates as a function of excess excitation energy, and its competition with the intersystem crossing process, are reviewed for the case of naphthalene vapor. A general expression for the spin-orbit interaction Hamiltonian in molecular systems is outlined. Experimental observations on singlet-triplet conversion rates and the factors that can drastically affect such rates are discussed, with emphasis on the ''in- ternal'' and ''external'' heavy-atom effects. Basic relations of ESR spectroscopy and magnetophotoselection are reviewed. Technological implications of the singlet-triplet crossing in complex molecules are discussed in the context of chelate lasers, dye lasers and luminescent displays. Effects related to singlet-triplet crossing, and generally to excited-state energy-transfer in biological systems, are exemplified by the role of aromatic amino-acids in the phosphorescence of proteins, by some recent studies of energy-transfer in models of biomembranes, and by the clustering of triplet-energy donor-acceptor pairs in micelles

  12. Cellular Adhesion and Adhesion Molecules

    OpenAIRE

    SELLER, Zerrin

    2014-01-01

    In recent years, cell adhesion and cell adhesion molecules have been shown to be important for many normal biological processes, including embryonic cell migration, immune system functions and wound healing. It has also been shown that they contribute to the pathogenesis of a large number of common human disorders, such as rheumatoid arthritis and tumor cell metastasis in cancer. In this review, the basic mechanisms of cellular adhesion and the structural and functional features of adhes...

  13. Electron interactions with polar molecules

    International Nuclear Information System (INIS)

    Garrett, W.R.

    1981-01-01

    A description is given of a number of the features of discrete and continuous spectra of electrons interacting with polar molecules. Attention is focused on the extent to which theoretical predictions concerning cross sections, resonances, and bound states are strongly influenced by the various approximations that are so ubiquitous in the treatment of such problems. Similarly, threshold scattering and photodetachment processes are examined for the case of weakly bound dipole states whose higher members overlap the continuum

  14. A single-molecule diode

    Science.gov (United States)

    Elbing, Mark; Ochs, Rolf; Koentopp, Max; Fischer, Matthias; von Hänisch, Carsten; Weigend, Florian; Evers, Ferdinand; Weber, Heiko B.; Mayor, Marcel

    2005-01-01

    We have designed and synthesized a molecular rod that consists of two weakly coupled electronic π -systems with mutually shifted energy levels. The asymmetry thus implied manifests itself in a current–voltage characteristic with pronounced dependence on the sign of the bias voltage, which makes the molecule a prototype for a molecular diode. The individual molecules were immobilized by sulfur–gold bonds between both electrodes of a mechanically controlled break junction, and their electronic transport properties have been investigated. The results indeed show diode-like current–voltage characteristics. In contrast to that, control experiments with symmetric molecular rods consisting of two identical π -systems did not show significant asymmetries in the transport properties. To investigate the underlying transport mechanism, phenomenological arguments are combined with calculations based on density functional theory. The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current–voltage characteristics, similar to the phenomena in a semiconductor diode. PMID:15956208

  15. The largest molecules in space

    International Nuclear Information System (INIS)

    Greenberg, J.M.

    1983-01-01

    The bulk of complex molecules in the space between the stars is shown to be in the small frozen particles of interstellar dust. Each dust grain typically contains some 10 9 atoms of oxygen, carbon and nitrogen in an amorphous molecular mixture. As a result of chemical processing of the particles by ultraviolet photons over times spanning proportional10 8 -10 9 years a substantial portion of each dust grain is converted into complex organic molecules whose maximum molecular weight is limited only by the size of the grain. Laboratory studies of evolution of analog grain materials shows that molecular weights of the order of 500 are readily created and that there is an excellent probability of much more complex molecules being produced. The organic dust component constitutes about one tenth of a percent of the total mass of the Milky Way and far outweighs any estimates of the total mass of all the planets. A planet like the earth is continually accreting matter from space and there was a high probability that in the first five hundred million years after its crust formed it passed through several dark clouds and accreted from a hundred million to ten thousand million tonnes of the organic material of the interstellar dust during each passage. It is suggested that this rain of material could have provided the molecular templates for the origin of life. (orig.)

  16. Electric moments in molecule interferometry

    International Nuclear Information System (INIS)

    Eibenberger, Sandra; Gerlich, Stefan; Arndt, Markus; Tuexen, Jens; Mayor, Marcel

    2011-01-01

    We investigate the influence of different electric moments on the shift and dephasing of molecules in a matter wave interferometer. Firstly, we provide a quantitative comparison of two molecules that are non-polar yet polarizable in their thermal ground state and that differ in their stiffness and response to thermal excitations. While C 25 H 20 is rather rigid, its larger derivative C 49 H 16 F 52 is additionally equipped with floppy side chains and vibrationally activated dipole moment variations. Secondly, we elucidate the role of a permanent electric dipole momentby contrasting the quantum interference pattern of a (nearly) non-polar and a polar porphyrin derivative. We find that a high molecular polarizability and even sizeable dipole moment fluctuations are still well compatible with high-contrast quantum interference fringes. The presence of permanent electric dipole moments, however, can lead to a dephasing and rapid degradation of the quantum fringe pattern already at moderate electric fields. This finding is of high relevance for coherence experiments with large organic molecules, which are generally equipped with strong electric moments.

  17. Le décodage biologique. Diffusion d’une nouvelle médecine non-conventionnelle contre le cancer Biodecoding. Dissemination of a New Unconventional Therapy against Cancer

    Directory of Open Access Journals (Sweden)

    Aline Sarradon-Eck

    2011-05-01

    Full Text Available De nouvelles médecines alternatives, regroupées sous l’appellation « décodage biologique », reposent sur une conception psychosomatique du cancer. Elles sont apparues en Europe dans les années 1990. Dans une perspective critique, l’article tente de comprendre la diffusion de ces nouvelles thérapies. S’inspirant du travail de D. Fassin sur les réseaux de l’ethnopsychiatrie, il analyse la construction d’une légitimation du décodage biologique et de ses praticiens, en décrivant les réseaux qui diffusent les théories et favorisent l’adoption de la pratique. L’article montre l’enracinement de ces nouvelles thérapies dans des représentations sociales et des modèles culturels de l’étiologie du cancer et du “faire face” à la maladie qui permettent ou renforcent l’adoption et l’appropriation de la pensée psychosomatique alternative.New alternative therapy called « bio-decoding » based on a psychosomatic perception of cancer appeared in the 1990s. Using a critical approach, the article aims to understand the therapy’s growth. Drawing on D. Fassin’s work about ethnopsychiatric networks, this paper analyses the construction of bio-decoding and bio-therapist legitimacy, by unravelling the networks which allow for theory dissemination and enable the practice’s growth. The article shows that these new therapies are deeply rooted in social and cultural models of cancer etiology and coping, which allow or reinforce approval and appropriation of alternative psychosomatic thought.

  18. Adoption et retombées d'une nouvelle technologie de dépistage des infections à ERV en contexte hospitalier québécois

    OpenAIRE

    Attieh, Randa

    2015-01-01

    La « Polymerase Chain Reaction» (PCR) est une technologie moléculaire qui se veut performante pour détecter les entérocoques résistants à la vancomycine (ERV) en contexte hospitalier. La traduction de cette technologie dans les pratiques professionnelles des acteurs est conceptualisée comme un processus d’adaptation et d’ajustements des rôles entre la technologie et le milieu hospitalier. Par souci de mieux comprendre la traduction de la nouvelle technologie de dépistage PCR dans les pratique...

  19. Creation, synthesis and characterisation of nitrogenous poly-heterocyclic new molecules for specific complexation of metallic cations; Conception, synthese et caracterisation de molecules polyheterocycliques azotees pour la complexation specifique de cations metalliques

    Energy Technology Data Exchange (ETDEWEB)

    Dupont, C.

    2010-12-10

    radioelements a vie longue, pour reduire les quantites et la nocivite des dechets radioactifs ultimes. Ces dechets issus du retraitement du combustible nucleaire use sont actuellement vitrifies a La Hague. Ainsi, le projet 'separation poussee' vise a completer le procede industriel PUREX par le developpement de procedes permettant d'extraire les actinides mineurs des raffinats PUREX ou se trouvent egalement des produits de fission constitues principalement de lanthanides, neutrophages. Pour realiser la separation poussee, les actinides mineurs des raffinats PUREX doivent etre separes par des molecules specifiques. Les BTP ou bis-triazinyl-pyridines ont ete largement etudiees au CEA pour la separation actinides(III)/lanthanides(III). Elles complexent selectivement les actinides, mais l'origine de cette selectivite n'est pas completement expliquee: notamment l'influence des groupements (attaches a leur structure) sur la complexation ou la selectivite reste a demontrer. En outre, elles sont sensibles a l'hydrolyse et a la radiolyse. La premiere partie du travail presente la synthese de BTP ou de BTBP, differemment substituees pour ameliorer leur resistance face a l'hydrolyse ou a la radiolyse, et une nouvelle famille de ligands polyaromatiques azotes: les BPBT, presentant un enchainement original de cycles pyridine et triazine, different de toutes les structures decrites jusqu'a present dans la litterature. La seconde partie de ce travail est consacree a l'etude physico-chimique de nouvelles molecules obtenues, en determinant leurs constantes de protonation et de complexation, pour connaitre l'influence des differents groupements sur la complexation et la selectivite. Enfin, le troisieme volet concerne l'etude des proprietes de ces ligands en extraction liquide-liquide, utilises soit comme extractants lipophiles, soit comme complexants hydrophiles. (auteur)

  20. Single Molecule Nano-Metronome

    OpenAIRE

    Buranachai, Chittanon; McKinney, Sean A.; Ha, Taekjip

    2006-01-01

    We constructed a DNA-based nano-mechanical device called the nano-metronome. Our device is made by introducing complementary single stranded overhangs at the two arms of the DNA four-way junction. The ticking rates of this stochastic metronome depend on ion concentrations and can be changed by a set of DNA-based switches to deactivate/reactivate the sticky end. Since the device displays clearly distinguishable responses even with a single basepair difference, it may lead to a single molecule ...

  1. Single Molecule Nano-Metronome

    Science.gov (United States)

    Buranachai, Chittanon; McKinney, Sean A.; Ha, Taekjip

    2008-01-01

    We constructed a DNA-based nano-mechanical device called the nano-metronome. Our device is made by introducing complementary single stranded overhangs at the two arms of the DNA four-way junction. The ticking rates of this stochastic metronome depend on ion concentrations and can be changed by a set of DNA-based switches to deactivate/reactivate the sticky end. Since the device displays clearly distinguishable responses even with a single basepair difference, it may lead to a single molecule sensor of minute sequence differences of a target DNA. PMID:16522050

  2. XUV ionization of aligned molecules

    Energy Technology Data Exchange (ETDEWEB)

    Kelkensberg, F.; Siu, W.; Gademann, G. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Rouzee, A.; Vrakking, M. J. J. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Max-Born-Institut, Max-Born Strasse 2A, D-12489 Berlin (Germany); Johnsson, P. [FOM Institute AMOLF, Science Park 104, NL-1098 XG Amsterdam (Netherlands); Department of Physics, Lund University, Post Office Box 118, SE-221 00 Lund (Sweden); Lucchini, M. [Department of Physics, Politecnico di Milano, Istituto di Fotonica e Nanotecnologie CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Lucchese, R. R. [Department of Chemistry, Texas A and M University, College Station, Texas 77843-3255 (United States)

    2011-11-15

    New extreme-ultraviolet (XUV) light sources such as high-order-harmonic generation (HHG) and free-electron lasers (FELs), combined with laser-induced alignment techniques, enable novel methods for making molecular movies based on measuring molecular frame photoelectron angular distributions. Experiments are presented where CO{sub 2} molecules were impulsively aligned using a near-infrared laser and ionized using femtosecond XUV pulses obtained by HHG. Measured electron angular distributions reveal contributions from four orbitals and the onset of the influence of the molecular structure.

  3. ''Crown molecules'' for separating cesium

    International Nuclear Information System (INIS)

    Dozol, J.F.; Lamare, V.

    2002-01-01

    After the minor actinides, the second category of radionuclides that must be isolated to optimize nuclear waste management concerns fission products, especially two cesium isotopes. If the cesium-135 isotope could be extracted, it could subsequently be transmuted or conditioned using a tailor-made process. Eliminating the 137 isotope from reprocessing and nuclear facility-dismantling waste would allow to dispose of most of this waste in near-surface facilities, and simply process the small remaining quantity containing long-lived elements. CEA research teams and their international partners have thought up crown molecules that could be used to pick out the cesium and meet these objectives. (authors)

  4. XUV ionization of aligned molecules

    International Nuclear Information System (INIS)

    Kelkensberg, F.; Siu, W.; Gademann, G.; Rouzee, A.; Vrakking, M. J. J.; Johnsson, P.; Lucchini, M.; Lucchese, R. R.

    2011-01-01

    New extreme-ultraviolet (XUV) light sources such as high-order-harmonic generation (HHG) and free-electron lasers (FELs), combined with laser-induced alignment techniques, enable novel methods for making molecular movies based on measuring molecular frame photoelectron angular distributions. Experiments are presented where CO 2 molecules were impulsively aligned using a near-infrared laser and ionized using femtosecond XUV pulses obtained by HHG. Measured electron angular distributions reveal contributions from four orbitals and the onset of the influence of the molecular structure.

  5. The neural cell adhesion molecule

    DEFF Research Database (Denmark)

    Berezin, V; Bock, E; Poulsen, F M

    2000-01-01

    During the past year, the understanding of the structure and function of neural cell adhesion has advanced considerably. The three-dimensional structures of several of the individual modules of the neural cell adhesion molecule (NCAM) have been determined, as well as the structure of the complex...... between two identical fragments of the NCAM. Also during the past year, a link between homophilic cell adhesion and several signal transduction pathways has been proposed, connecting the event of cell surface adhesion to cellular responses such as neurite outgrowth. Finally, the stimulation of neurite...

  6. The molecule-metal interface

    CERN Document Server

    Koch, Norbert; Wee, Andrew Thye Shen

    2013-01-01

    Reviewing recent progress in the fundamental understanding of the molecule-metal interface, this useful addition to the literature focuses on experimental studies and introduces the latest analytical techniques as applied to this interface.The first part covers basic theory and initial principle studies, while the second part introduces readers to photoemission, STM, and synchrotron techniques to examine the atomic structure of the interfaces. The third part presents photoelectron spectroscopy, high-resolution UV photoelectron spectroscopy and electron spin resonance to study the electroni

  7. Positron creation in superheavy quasi-molecules

    International Nuclear Information System (INIS)

    Mueller, B.

    1976-01-01

    The review of positron creation in superheavy quasi-molecules includes spontaneous positron emission from superheavy atoms, supercritical quasi-molecules, background effects, and some implications of the new ground state. 66 references

  8. Characterization of Interstellar Organic Molecules

    International Nuclear Information System (INIS)

    Gencaga, Deniz; Knuth, Kevin H.; Carbon, Duane F.

    2008-01-01

    Understanding the origins of life has been one of the greatest dreams throughout history. It is now known that star-forming regions contain complex organic molecules, known as Polycyclic Aromatic Hydrocarbons (PAHs), each of which has particular infrared spectral characteristics. By understanding which PAH species are found in specific star-forming regions, we can better understand the biochemistry that takes place in interstellar clouds. Identifying and classifying PAHs is not an easy task: we can only observe a single superposition of PAH spectra at any given astrophysical site, with the PAH species perhaps numbering in the hundreds or even thousands. This is a challenging source separation problem since we have only one observation composed of numerous mixed sources. However, it is made easier with the help of a library of hundreds of PAH spectra. In order to separate PAH molecules from their mixture, we need to identify the specific species and their unique concentrations that would provide the given mixture. We develop a Bayesian approach for this problem where sources are separated from their mixture by Metropolis Hastings algorithm. Separated PAH concentrations are provided with their error bars, illustrating the uncertainties involved in the estimation process. The approach is demonstrated on synthetic spectral mixtures using spectral resolutions from the Infrared Space Observatory (ISO). Performance of the method is tested for different noise levels.

  9. Double-valence-fluctuating molecules and superconductivity

    International Nuclear Information System (INIS)

    Hirsch, J.E.; Scalapino, D.J.

    1985-01-01

    We discuss the possibility of ''double-valence-fluctuating'' molecules, having two ground-state configurations differing by two electrons. We propose a possible realization of such a molecule, and experimental ways to look for it. We argue that a weakly coupled array of such molecules should give rise to a strong-coupling Shafroth-Blatt-Butler superconductor, with a high transition temperature

  10. Trapping molecules in two and three dimensions

    International Nuclear Information System (INIS)

    Pinkse, PW.H.; Junglen, T.; Rieger, T.; Rangwala, S.A.; Windpassinger, P.; Rempe, G.

    2005-01-01

    Full text: Cold molecules offer a new testing ground for quantum-physical effects in nature. For example, producing slow beams of large molecules could push experiments studying the boundary between quantum interference and classical particles up towards ever heavier particles. Moreover, cold molecules, in particular YbF, seem an attractive way to narrow down the constraints on the value of the electron dipole moment and finally, quantum information processing using chains of cold polar molecules or vibrational states in molecules have been proposed. All these proposals rely on advanced production and trapping techniques, most of which are still under development. Therefore, novel production and trapping techniques for cold molecules could offer new possibilities not found in previous methods. Electric traps hold promise for deep trap potentials for neutral molecules. Recently we have demonstrated two-dimensional trapping of polar molecules in a four-wire guide using electrostatic and electrodynamic trapping techniques. Filled from a thermal effusive source, such a guide will deliver a beam of slow molecules, which is an ideal source for interferometry experiments with large molecules, for instance. Here we report about the extension of this work to three-dimensional trapping. Polar molecules with a positive Stark shift can be trapped in the minimum of an electrostatic field. We have successfully tested a large volume electrostatic trap for ND3 molecules. A special feature of this trap is that it can be loaded continuously from an electrostatic guide, at a temperature of a few hundred mK. (author)

  11. La RSE : nouvelle forme de dé-marchandisation du monde ? CSR: a new way of de-marchanisation of the world?

    Directory of Open Access Journals (Sweden)

    Richard Sobel

    2010-12-01

    Full Text Available Le mouvement dit de « RSE » entend concilier l’actuel mode d’accumulation à dominante financière avec certaines exigences sociales et environnementales. Or, ce mouvement s’inscrit assez bien dans l’analyse historique et institutionnaliste que Karl Polanyi a faite des limites de la marchandisation du monde. En effet, ce mouvement consiste à revenir sur la trop forte marchandisation du rapport à la nature et au travail qu’aurait entraîné le développement d’un capitalisme financiarisé. En réaction, ce mouvement mobilise l’engagement volontaire des entreprises pour bâtir une nouvelle « grande transformation », c’est-à-dire une forme inédite d’articulation entre le juste et l’efficace visant à assurer la viabilité du capitalisme. Cela revient à élargir l’engagement économique à autre chose que la simple maximisation des intérêts individuels de court terme. Cet article vise à exploiter cette proximité entre le mouvement de la RSE et l’analyse polanyienne de la marchandisation, proximité selon nous fructueuse et qui n’a jamais fait l’objet d’une analyse systématique. L’enjeu est de déterminer dans quelle mesure la RSE constitue aujourd’hui une réponse pertinente à la nécessaire gestion collective de la fiction que constitue la marchandisation apparente de la monnaie, de la terre et du travail.The movement says about "CSR" tries to reconcile the current financial mode of accumulation with certain social and environmental requirements. This movement joins well enough in the historic and institutionnalist analysis which Karl Polanyi made of the limits of marchandisation of the world. Indeed, this movement consists in returning on excess strong marchandisation of the relationship with the nature and with the work which would have pulled the new capitalism. In reaction, this movement mobilizes the individual commitment to build a new "great transformation", that is new articulation

  12. Littérature arabe en Israël : vers une sensibilité nouvelle Arabic Literature in Israel: Towards a New Sensibility ספרות ערבית בישראל

    Directory of Open Access Journals (Sweden)

    Sobhi Boustani

    2011-10-01

    Full Text Available La cause palestinienne chez les poètes arabes israéliens. Le présent article s’évertue à montrer les mouvements marquant l'évolution de la poésie arabe en Israël, dans un contexte contradictoire. Il souligne trois tendances principales. La première, explicitement militante, développée dans le giron de la Rakah, parti communiste israélien. Destinée à un public particulier et animée par une idéologie de combat, elle sacrifie parfois la poétique au profit de la politique. La deuxième tendance semble d'une nouvelle esthétique poétique basée sur l'individualité et l'expérience personnelle. La troisième voix poétique, profondément intimiste, est représentée par la poétesse Nida Khoury. Son approche de la résistance et du militantisme, ainsi que son approche originale de la langue révèle la profondeur d'une déchirure personnelle et la finesse d'un engagement subtilement exprimé.Enfin, le tiraillement intérieur entre deux appartenances et la recherche identitaire constituent l'un des principaux thèmes qui unissent les poètes de ces trois tendances.The present article focuses on showing the movements marking the evolution of Arabic poetry in Israel in a conflicting context. It points out three main tendencies. The first one, explicitly militant, developed in the lap of the Israeli communist party Rakah. Intended for a general public and animated by an ideology of fight, it sometimes sacrifices the poetics for the benefit of politics. The second tendency looks for a new poetic aesthetics based on individuality and personal experience. The third poetic voice, profoundly intimist, is represented by the poet Nidâ 'Khoury. Its approach of the resistance and the militancy as well as its original approach of the language reveal the depth of a personal tearing and the finesse of a subtly expressed commitment.Finally, the interior tugging between two belongings and the identical seeking constitute one of the main themes

  13. A single-molecule diode

    Science.gov (United States)

    Elbing, Mark; Ochs, Rolf; Koentopp, Max; Fischer, Matthias; von Hänisch, Carsten; Weigend, Florian; Evers, Ferdinand; Weber, Heiko B.; Mayor, Marcel

    2005-06-01

    We have designed and synthesized a molecular rod that consists of two weakly coupled electronic π -systems with mutually shifted energy levels. The asymmetry thus implied manifests itself in a current-voltage characteristic with pronounced dependence on the sign of the bias voltage, which makes the molecule a prototype for a molecular diode. The individual molecules were immobilized by sulfur-gold bonds between both electrodes of a mechanically controlled break junction, and their electronic transport properties have been investigated. The results indeed show diode-like current-voltage characteristics. In contrast to that, control experiments with symmetric molecular rods consisting of two identical π -systems did not show significant asymmetries in the transport properties. To investigate the underlying transport mechanism, phenomenological arguments are combined with calculations based on density functional theory. The theoretical analysis suggests that the bias dependence of the polarizability of the molecule feeds back into the current leading to an asymmetric shape of the current-voltage characteristics, similar to the phenomena in a semiconductor diode. Author contributions: F.E., H.B.W., and M.M. designed research; M.E., R.O., M.K., M.F., F.E., H.B.W., and M.M. performed research; M.E., R.O., M.K., M.F., C.v.H., F.W., F.E., H.B.W., and M.M. contributed new reagents/analytic tools; M.E., R.O., M.K., C.v.H., F.E., H.B.W., and M.M. analyzed data; and F.E., H.B.W., and M.M. wrote the paper.This paper was submitted directly (Track II) to the PNAS office.Abbreviations: A, acceptor; D, donor; MCB, mechanically controlled break junction.Data deposition: The atomic coordinates have been deposited in the Cambridge Structural Database, Cambridge Crystallographic Data Centre, Cambridge CB2 1EZ, United Kingdom (CSD reference no. 241632).

  14. Dissociation Energies of Diatomic Molecules

    International Nuclear Information System (INIS)

    Qun-Chao, Fan; Wei-Guo, Sun

    2008-01-01

    Molecular dissociation energies of 10 electronic states of alkali molecules of KH, 7 LiD, 7 LiH, 6 LiH, NaK, NaLi and NaRb are studied using the highest three accurate vibrational energies of each electronic state, and an improved parameter-free analytical formula which is obtained starting from the LeRoy–Bernstein vibrational energy expression near the dissociation limit. The results show that as long as the highest three vibrational energies are accurate, the current analytical formula will give accurate theoretical dissociation energies D e theory , which are in excellent agreement with the experimental dissociation energies D e expt . (atomic and molecular physics)

  15. Generalizations of the Toda molecule

    Science.gov (United States)

    Van Velthoven, W. P. G.; Bais, F. A.

    1986-12-01

    Finite-energy monopole solutions are constructed for the self-dual equations with spherical symmetry in an arbitrary integer graded Lie algebra. The constraint of spherical symmetry in a complex noncoordinate basis leads to a dimensional reduction. The resulting two-dimensional ( r, t) equations are of second order and furnish new generalizations of the Toda molecule equations. These are then solved by a technique which is due to Leznov and Saveliev. For time-independent solutions a further reduction is made, leading to an ansatz for all SU(2) embeddings of the Lie algebra. The regularity condition at the origin for the solutions, needed to ensure finite energy, is also solved for a special class of nonmaximal embeddings. Explicit solutions are given for the groups SU(2), SO(4), Sp(4) and SU(4).

  16. Optoelectronics of Molecules and Polymers

    CERN Document Server

    Moliton, André

    2006-01-01

    Optoelectronic devices are being developed at an extraordinary rate. Organic light emitting diodes, photovoltaic devices and electro-optical modulators are pivotal to the future of displays, photosensors and solar cells, and communication technologies. This book details the theories underlying the relevant mechanisms in organic materials and covers, at a basic level, how the organic components are made. The first part of this book introduces the fundamental theories used to detail ordered solids and localised energy levels. The methods used to determine energy levels in perfectly ordered molecular and macromolecular systems are discussed, making sure that the effects of quasi-particles are not missed. The function of excitons and their transfer between two molecules are studied, and the problems associated with interfaces and charge injection into resistive media are presented. The second part details technological aspects such as the fabrication of devices based on organic materials by dry etching. The princ...

  17. Anti-cancer Lead Molecule

    KAUST Repository

    Sagar, Sunil

    2014-04-17

    Derivatives of plumbagin can be selectively cytotoxic to breast cancer cells. Derivative `A` (Acetyl Plumbagin) has emerged as a lead molecule for testing against estrogen positive breast cancer and has shown low hepatotoxicity as well as overall lower toxicity in nude mice model. The toxicity of derivative `A` was determined to be even lower than vehicle control (ALT and AST markers). The possible mechanism of action identified based on the microarray experiments and pathway mapping shows that derivative `A` could be acting by altering the cholesterol-related mechanisms. The low toxicity profile of derivative `A` highlights its possible role as future anti-cancer drug and/or as an adjuvant drug to reduce the toxicity of highly toxic chemotherapeutic drugs

  18. Anti-cancer Lead Molecule

    KAUST Repository

    Sagar, Sunil; Kaur, Mandeep; Esau, Luke E.

    2014-01-01

    Derivatives of plumbagin can be selectively cytotoxic to breast cancer cells. Derivative `A` (Acetyl Plumbagin) has emerged as a lead molecule for testing against estrogen positive breast cancer and has shown low hepatotoxicity as well as overall lower toxicity in nude mice model. The toxicity of derivative `A` was determined to be even lower than vehicle control (ALT and AST markers). The possible mechanism of action identified based on the microarray experiments and pathway mapping shows that derivative `A` could be acting by altering the cholesterol-related mechanisms. The low toxicity profile of derivative `A` highlights its possible role as future anti-cancer drug and/or as an adjuvant drug to reduce the toxicity of highly toxic chemotherapeutic drugs

  19. Hydride Molecules towards Nearby Galaxies

    Science.gov (United States)

    Monje, Raquel R.; La, Ngoc; Goldsmith, Paul

    2018-06-01

    Observations carried out by the Herschel Space Observatory revealed strong spectroscopic signatures from light hydride molecules within the Milky Way and nearby active galaxies. To better understand the chemical and physical conditions of the interstellar medium, we conducted the first comprehensive survey of hydrogen fluoride (HF) and water molecular lines observed through the SPIRE Fourier Transform Spectrometer. By collecting and analyzing the sub-millimeter spectra of over two hundred sources, we found that the HF J = 1 - 0 rotational transition which occurs at approximately 1232 GHz was detected in a total of 39 nearby galaxies both in absorption and emission. The analysis will determine the main excitation mechanism of HF in nearby galaxies and provide steady templates of the chemistry and physical conditions of the ISM to be used in the early universe, where observations of hydrides are more scarce.

  20. Modelling of energetic molecule-surface interactions

    International Nuclear Information System (INIS)

    Kerford, M.

    2000-09-01

    This thesis contains the results of molecular dynamics simulations of molecule-surface interactions, looking particularly at fullerene molecules and carbon surfaces. Energetic impacts of fullerene molecules on graphite create defect craters. The relationship between the parameters of the impacting molecule and the parameters of the crater axe examined and found to be a function of the energy and velocity of the impacting molecule. Less energetic fullerene molecules can be scattered from a graphite surface and the partitioning of energy after a scattering event is investigated. It is found that a large fraction of the kinetic energy retained after impact is translational energy, with a small fraction of rotational energy and a number of vibrational modes. At impact energies where the surface is not broken and at normal incidence, surface waves axe seen to occur. These waves axe used to develop a method of desorbing molecules from a graphite surface without damage to either the surface or the molecules being desorbed. A number of fullerene molecules are investigated and ways to increase the desorption yield are examined. It is found that this is a successful technique for desorbing large numbers of intact molecules from graphite. This technique could be used for desorbing intact molecules into a gas phase for mass spectrometric analysis. (author)

  1. Observation of pendular butterfly Rydberg molecules

    Science.gov (United States)

    Niederprüm, Thomas; Thomas, Oliver; Eichert, Tanita; Lippe, Carsten; Pérez-Ríos, Jesús; Greene, Chris H.; Ott, Herwig

    2016-01-01

    Engineering molecules with a tunable bond length and defined quantum states lies at the heart of quantum chemistry. The unconventional binding mechanism of Rydberg molecules makes them a promising candidate to implement such tunable molecules. A very peculiar type of Rydberg molecules are the so-called butterfly molecules, which are bound by a shape resonance in the electron–perturber scattering. Here we report the observation of these exotic molecules and employ their exceptional properties to engineer their bond length, vibrational state, angular momentum and orientation in a small electric field. Combining the variable bond length with their giant dipole moment of several hundred Debye, we observe counter-intuitive molecules which locate the average electron position beyond the internuclear distance. PMID:27703143

  2. A Mott-like State of Molecules

    International Nuclear Information System (INIS)

    Duerr, S.; Volz, T.; Syassen, N.; Bauer, D. M.; Hansis, E.; Rempe, G.

    2006-01-01

    We prepare a quantum state where each site of an optical lattice is occupied by exactly one molecule. This is the same quantum state as in a Mott insulator of molecules in the limit of negligible tunneling. Unlike previous Mott insulators, our system consists of molecules which can collide inelastically. In the absence of the optical lattice these collisions would lead to fast loss of the molecules from the sample. To prepare the state, we start from a Mott insulator of atomic 87Rb with a central region, where each lattice site is occupied by exactly two atoms. We then associate molecules using a Feshbach resonance. Remaining atoms can be removed using blast light. Our method does not rely on the molecule-molecule interaction properties and is therefore applicable to many systems

  3. Single-molecule dynamics in nanofabricated traps

    Science.gov (United States)

    Cohen, Adam

    2009-03-01

    The Anti-Brownian Electrokinetic trap (ABEL trap) provides a means to immobilize a single fluorescent molecule in solution, without surface attachment chemistry. The ABEL trap works by tracking the Brownian motion of a single molecule, and applying feedback electric fields to induce an electrokinetic motion that approximately cancels the Brownian motion. We present a new design for the ABEL trap that allows smaller molecules to be trapped and more information to be extracted from the dynamics of a single molecule than was previously possible. In particular, we present strategies for extracting dynamically fluctuating mobilities and diffusion coefficients, as a means to probe dynamic changes in molecular charge and shape. If one trapped molecule is good, many trapped molecules are better. An array of single molecules in solution, each immobilized without surface attachment chemistry, provides an ideal test-bed for single-molecule analyses of intramolecular dynamics and intermolecular interactions. We present a technology for creating such an array, using a fused silica plate with nanofabricated dimples and a removable cover for sealing single molecules within the dimples. With this device one can watch the shape fluctuations of single molecules of DNA or study cooperative interactions in weakly associating protein complexes.

  4. Bangalore, ville des nouvelles technologies

    Directory of Open Access Journals (Sweden)

    Clarisse Didelon

    2003-06-01

    Full Text Available Bangalore est devenue la Silicon Valley de l’Inde. Une partie de ses habitants y vit à l’occidentale mais le reste de la population souffre de la croissance spectaculaire de la ville. Face à l’insuffisance des infrastructures, Bangalore devient de moins en moins attractive pour les entreprises internationales.

  5. NMR of dielectrically oriented molecules

    International Nuclear Information System (INIS)

    Ruessink, B.H.

    1986-01-01

    General information on experimental aspects of EFNMR is given. It is shown that the complete 14 N quadrupole tensor (qct) of pyridine and pyrimidine in the liquid state is accessible to EFNMR. Information obtained about 17 O qct in liquid nitromethane, is compared with results from other techniques. The 33 S qct in liquid sulfolane is investigated. The EFNMR results, combined with those from spin-lattice relaxation time measurements and from Hartree-Fock-Slater MO calculations, allowed the complete assignment of the 33 S qct. The quadrupole coupling of both 10 B and 11 B in a carborane compound is investigated and, together with the results of spin-lattice relaxation time measurements, detailed information about the assignment of the boron qct's could be derived. EFNMR studies of apolar molecules are described. A limitation in EFNMR is the inhomogeneity (delta B) of the magnetic field, which is introduced by the use of non-spinning sample cells. A way out is the detection of zero quantum transitions, their widths being independent of delta B. The results and prospectives of this approach are shown for the simple three spin 1/2 system of acrylonitrile in which the small dipolar proton-proton couplings could be revealed via zero quantum transitions. (Auth.)

  6. Single-Molecule Stochastic Resonance

    Directory of Open Access Journals (Sweden)

    K. Hayashi

    2012-08-01

    Full Text Available Stochastic resonance (SR is a well-known phenomenon in dynamical systems. It consists of the amplification and optimization of the response of a system assisted by stochastic (random or probabilistic noise. Here we carry out the first experimental study of SR in single DNA hairpins which exhibit cooperatively transitions from folded to unfolded configurations under the action of an oscillating mechanical force applied with optical tweezers. By varying the frequency of the force oscillation, we investigate the folding and unfolding kinetics of DNA hairpins in a periodically driven bistable free-energy potential. We measure several SR quantifiers under varied conditions of the experimental setup such as trap stiffness and length of the molecular handles used for single-molecule manipulation. We find that a good quantifier of the SR is the signal-to-noise ratio (SNR of the spectral density of measured fluctuations in molecular extension of the DNA hairpins. The frequency dependence of the SNR exhibits a peak at a frequency value given by the resonance-matching condition. Finally, we carry out experiments on short hairpins that show how SR might be useful for enhancing the detection of conformational molecular transitions of low SNR.

  7. Laser spectroscopy on organic molecules.

    Science.gov (United States)

    Imasaka, T

    1996-06-01

    Various laser spectrometric methods have been developed until now. Especially, laser fluorometry is most sensitive and is frequently combined with a separation technique such as capillary electrophoresis. For non-fluorescent compounds, photothermal spectrometry may be used instead. A diode laser is potentially useful for practical trace analysis, because of its low cost and long-term trouble-free operation. On the other hand, monochromaticity of the laser is essential in high-resolution spectrometry, e.g. in low temperature spectrometry providing a very sharp spectral feature. Closely-related compounds such as isomers can easily be differentiated, and information for assignment is obtained from the spectrum. Multiphoton ionization mass spectrometry is useful for soft ionization, providing additional information concerned with molecular weight and chemical structure. A short laser pulse with a sufficient energy is suitable for rapid heating of the solid surface. A matrix-assisted laser desorption/ion-ization technique is recently employed for introduction of a large biological molecule into a vacuum for mass analysis. In the future, laser spectrometry will be developed by a combination with state-of-the-art laser technology. In the 21st century, new laser spectrometry will be developed, which may be based on revolutionary ideas or unexpected discoveries. Such studies will open new frontiers in analytical laser spectroscopy.

  8. Isotope separation using vibrationally excited molecules

    International Nuclear Information System (INIS)

    Woodroffe, J.A.; Keck, J.C.

    1977-01-01

    A system for isotope separation or enrichment wherein molecules of a selected isotope type in a flow of molecules of plural isotope types are vibrationally excited and collided with a background gas to provide enhanced diffusivity for the molecules of the selected isotope type permitting their separate collection. The system typically is for the enrichment of uranium using a uranium hexafluoride gas in combination with a noble gas such as argon. The uranium hexafluoride molecules having a specific isotope of uranium are vibrationally excited by laser radiation. The vibrational energy is converted to a translation energy upon collision with a particle of the background gas and the added translation energy enhances the diffusivity of the selected hexafluoride molecules facilitating its condensation on collection surfaces provided for that purpose. This process is periodically interrupted and the cryogenic flow halted to permit evaporation of the collected molecules to provide a distinct, enriched flow

  9. Individual Magnetic Molecules on Ultrathin Insulating Surfaces

    Science.gov (United States)

    El Hallak, Fadi; Warner, Ben; Hirjibehedin, Cyrus

    2012-02-01

    Single molecule magnets have attracted ample interest because of their exciting magnetic and quantum properties. Recent studies have demonstrated that some of these molecules can be evaporated on surfaces without losing their magnetic properties [M. Mannini et al., Nature 468, 417, (2010)]. This remarkable progress enhances the chances of real world applications for these molecules. We present STM imaging and spectroscopy data on iron phthalocyanine molecules deposited on Cu(100) and on a Cu2N ultrathin insulating surface. These molecules have been shown to display a large magnetic anisotropy on another thin insulating surface, oxidized Cu(110) [N. Tsukahara et al., Phys. Rev. Lett. 102, 167203 (2009)]. By using a combination of elastic and inelastic electron tunnelling spectroscopy, we investigate the binding of the molecules to the surface and the impact that the surface has on their electronic and magnetic properties.

  10. Single molecule detection, thermal fluctuation and life

    Science.gov (United States)

    YANAGIDA, Toshio; ISHII, Yoshiharu

    2017-01-01

    Single molecule detection has contributed to our understanding of the unique mechanisms of life. Unlike artificial man-made machines, biological molecular machines integrate thermal noises rather than avoid them. For example, single molecule detection has demonstrated that myosin motors undergo biased Brownian motion for stepwise movement and that single protein molecules spontaneously change their conformation, for switching to interactions with other proteins, in response to thermal fluctuation. Thus, molecular machines have flexibility and efficiency not seen in artificial machines. PMID:28190869

  11. Nuclei quadrupole coupling constants in diatomic molecule

    International Nuclear Information System (INIS)

    Ivanov, A.I.; Rebane, T.K.

    1993-01-01

    An approximate relationship between the constants of quadrupole interaction of nuclei in a two-atom molecule is found. It enabled to establish proportionality of oscillatory-rotation corrections to these constants for both nuclei in the molecule. Similar results were obtained for the factors of electrical dipole-quadrupole screening of nuclei. Applicability of these relationships is proven by the example of lithium deuteride molecule. 4 refs., 1 tab

  12. Carbon chain molecules in interstellar clouds

    International Nuclear Information System (INIS)

    Winnewisser, G.; Walmsley, C.M.

    1979-01-01

    A survey of the distribution of long carbon chain molecules in interstellar clouds shows that their abundance is correlated. The various formation schemes for these molecules are discussed. It is concluded that the ion-molecule type formation mechanisms are more promising than their competitors. They have also the advantage of allowing predictions which can be tested by observations. Acetylene C 2 H 2 and diacetylene HCCCCH, may be very abundant in interstellar clouds. (Auth.)

  13. Electron-molecule interactions and their applications

    CERN Document Server

    Christophorou, L G

    1984-01-01

    Electron-Molecule Interactions and Their Applications, Volume 2 provides a balanced and comprehensive account of electron-molecule interactions in dilute and dense gases and liquid media. This book consists of six chapters. Chapter 1 deals with electron transfer reactions, while Chapter 2 discusses electron-molecular positive-ion recombination. The electron motion in high-pressure gases and electron-molecule interactions from single- to multiple-collision conditions is deliberated in Chapter 3. In Chapter 4, knowledge on electron-molecule interactions in gases is linked to that on similar proc

  14. Conserved water molecules in bacterial serine hydroxymethyltransferases.

    Science.gov (United States)

    Milano, Teresa; Di Salvo, Martino Luigi; Angelaccio, Sebastiana; Pascarella, Stefano

    2015-10-01

    Water molecules occurring in the interior of protein structures often are endowed with key structural and functional roles. We report the results of a systematic analysis of conserved water molecules in bacterial serine hydroxymethyltransferases (SHMTs). SHMTs are an important group of pyridoxal-5'-phosphate-dependent enzymes that catalyze the reversible conversion of l-serine and tetrahydropteroylglutamate to glycine and 5,10-methylenetetrahydropteroylglutamate. The approach utilized in this study relies on two programs, ProACT2 and WatCH. The first software is able to categorize water molecules in a protein crystallographic structure as buried, positioned in clefts or at the surface. The other program finds, in a set of superposed homologous proteins, water molecules that occur approximately in equivalent position in each of the considered structures. These groups of molecules are referred to as 'clusters' and represent structurally conserved water molecules. Several conserved clusters of buried or cleft water molecules were found in the set of 11 bacterial SHMTs we took into account for this work. The majority of these clusters were not described previously. Possible structural and functional roles for the conserved water molecules are envisaged. This work provides a map of the conserved water molecules helpful for deciphering SHMT mechanism and for rational design of molecular engineering experiments. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  15. Energy storage and redistribution in molecules

    International Nuclear Information System (INIS)

    Hinze, J.

    1983-01-01

    This book presents information on the following topics: chemistry and spectroscopy of molecules at high levels of excitation; energy and phase randomization in large molecules as probed by laser spectroscopy; intramolecular processes in isolated polyatomic molecules; pulse-probe measurements in low-temperature, low-pressure SF 6 ; the photodissociation dynamics of H 2 S and CF 3 NO; photofragment spectroscopy of the NO 2 dissociation; preparation, laser spectroscopy and predissociation of alkali dimers in supersonic nozzle beams; excited states of small molecules - collisional quenching and photodissociation; quantum-state-resolved scattering of lithium hydride; and molecular negative ions

  16. Synthesis of amphiphilic macrocyclic molecules from family of aza-porphyrins and study in Langmuir-Blodgett films; Synthese de molecules macrocycliques amphiphiles de la famille des azaporphyrines et etude en films de Langmuir-Blodgett

    Energy Technology Data Exchange (ETDEWEB)

    Palacin, Serge

    1988-03-04

    The cellular automata, also called formal neurons, directly inspired by the knowledge concerning the nervous system, are able to mimic some basic processes of brain, as shape recognition, connecting memory, information sorting... This work aims to build a molecular structure able to fit the working rules of a bidimensional cellular automata. So, amphiphilic molecules belonging to the aza-porphyrin family are synthesized and organized into a planar paving by the Langmuir-Blodgett technique. The regular structure of the outcoming ultra-thin films is studied by linear dichroism and anisotropic electron spin resonance. The physico-chemical behaviour of the amphiphilic molecules is studied and brings about an explanation of the redox phenomena which are observed on the monomolecular film on the water surface. So are we able to outline the future chemical addressing ways of the bidimensional cellular automata. In the end of this dissertation, different ways likely to insure covalent bindings between the active sites and allow the transfer of information within the cellular network are discussed. (author) [French] Les reseaux d'automates, aussi appeles neurones formels, directement inspires par les connaissances nouvelles concernant le fonctionnement du systeme nerveux, sont a l'heure actuelle capables de reproduire certaines operations fondamentales du cerveau, telles que la reconnaissance de forme, la memoire associative, le tri d'information... Le travail a pour but de realiser une structure moleculaire susceptible d'obeir aux regles de fonctionnement d'un automate cellulaire bi-dimensionnel. Dans ce but, des molecules amphiphiles de la famille des azaporphyrines sont synthetisees et organisees en un pavage plan par la methode de Langmuir-Blodgett. La structure reguliere des films ultraminces obtenus est determinee par dichroisme lineaire et resonance paramagnetique electronique anisotrope. Les caracteristiques physico-chimiques des molecules amphiphiles sont etudiees

  17. Structure formation in bis(terpyridine) derivative adlayers: molecule-substrate versus molecule-molecule interactions.

    Science.gov (United States)

    Hoster, Harry E; Roos, Matthias; Breitruck, Achim; Meier, Christoph; Tonigold, Katrin; Waldmann, Thomas; Ziener, Ulrich; Landfester, Katharina; Behm, R Jürgen

    2007-11-06

    The influence of the substrate and the deposition conditions-vapor deposition versus deposition from solution-on the structures formed upon self-assembly of deposited bis(terpyridine) derivative (2,4'-BTP) monolayers on different hexagonal substrates, including highly oriented pyrolytic graphite (HOPG), Au(111), and (111)-oriented Ag thin films, was investigated by high-resolution scanning tunneling microscopy and by model calculations of the intermolecular energies and the lateral corrugation of the substrate-adsorbate interaction. Similar quasi-quadratic network structures with almost the same lattice constants obtained on all substrates are essentially identical to the optimum configuration expected from an optimization of the adlayer structure with C-H...N-type bridging bonds as a structure-determining factor, which underlines a key role of the intermolecular interactions in adlayer order. Slight distortions from the optimum values to form commensurate adlayer structures on the metal substrates and the preferential orientation of the adlayer with respect to the substrate are attributed to the substrate-adsorbate interactions, specifically, the lateral corrugation in the substrate-adsorbate interaction upon lateral displacement and rotation of the adsorbed BTP molecules. The fact that similar adlayer structures are obtained on HOPG under ultrahigh vacuum conditions (solid|gas interface) and on HOPG in trichlorobenzene (solid|liquid interface) indicates that the intermolecular interactions are not severely affected by the solvent.

  18. Spectroscopy and Chemistry of Cold Molecules

    Science.gov (United States)

    Momose, Takamasa

    2012-06-01

    Molecules at low temperatures are expected to behave quite differently from those at high temperatures because pronounced quantum effects emerge from thermal averages. Even at 10 K, a significant enhancement of reaction cross section is expected due to tunneling and resonance effects. Chemistry at this temperature is very important in order to understand chemical reactions in interstellar molecular clouds. At temperatures lower than 1 K, collisions and intermolecular interactions become qualitatively different from those at high temperatures because of the large thermal de Broglie wavelength of molecules. Collisions at these temperatures must be treated as the interference of molecular matter waves, but not as hard sphere collisions. A Bose-Einstein condensate is a significant state of matter as a result of coherent matter wave interaction. Especially, dense para-H_2 molecules are predicted to become a condensate even around 1 K. A convenient method to investigate molecules around 1 K is to dope molecules in cold matrices. Among various matrices, quantum hosts such as solid para-H_2 and superfluid He nano-droplets have been proven to be an excellent host for high-resolution spectroscopy. Rovibrational motion of molecules in these quantum hosts is well quantized on account of the weak interactions and the softness of quantum environment. The linewidths of infrared spectra of molecules in the quantum hosts are extremely narrow compared with those in other matrices. The sharp linewidths allow us to resolve fine spectral structures originated in subtle interactions between guest and host molecules. In this talk, I will describe how the splitting and lineshape of high-resolution spectra of molecules in quantum hosts give us new information on the static and dynamical interactions of molecules in quantum medium. The topics include dynamical response of superfluid environment upon rotational excitation, and possible superfluid phase of para-H_2 clusters. I will also

  19. « Société de l'information », deuxième époque ? Transformation du statut de l'usage des TIC au travers des nouvelles propriétés des objets communicants

    OpenAIRE

    Weygand, Félix

    2007-01-01

    Notre contribution présente brièvement ce qu'on décrit actuellement comme de nouvelles ruptures techniques en cours dans les TIC. Il s'agira d'une part de repérer les « effets de mode » contenus dans ces descriptions, qui reprennent des appréhensions ou des enthousiasmes récurrents dès que l'on est confronté à des ruptures techniques, d'autre part de s'interroger sur la pertinence de nos outils d'analyse des innovations face à ces éventuelles ruptures. En effet, indépendamment de l'opinion op...

  20. Nouvelles perspectives dans la littérature brésilienne contemporaine : Vozes-Mulheres et Quantos filhos Natalina teve ? de Conceição Evaristo

    OpenAIRE

    Champagnat, Pauline

    2017-01-01

    Cet article se propose d’analyser une des manifestations du féminisme brésilien contemporain dans les oeuvres Vozes-Mulheres (1990) et Quantos filhos Natalina teve ? (2015) de Conceição Evaristo sous le prisme des études de genre et des études post-coloniales. Dans un premier temps, nous questionnerons une nouvelle branche du féminisme brésilien : l’intersectionnalité. Après une brève définition du concept, nous expliquerons de quelle manière il s’insère dans le contexte du féminisme brésilie...

  1. Le commerce transnational « informel », vecteur d’une nouvelle hiérarchie de lieux. L’exemple de la périphérie urbaine de Salé (Maroc)

    OpenAIRE

    Bennafla, Karine

    2016-01-01

    Cet article examine les implications spatiales du commerce transnational dans les pays intermédiaires tel le Maroc. Si l’accentuation des réformes néo-libérales entraîne l’ouverture de grandes surfaces, de magasins franchisés ou de malls, elle ne signe pas la fin du commerce « informel », tout aussi globalisé. La nouvelle hiérarchisation de lieux sous l’effet du commerce transnational est peu abordée dans la littérature sur le commerce informel marocain. L’exemple d’une centralité marchande i...

  2. Une nouvelle orientation dans l’enseignement supérieur au vietnam: de la mémoire à la résolution de problèmes

    Directory of Open Access Journals (Sweden)

    TRƯƠNG Quang Dũng

    2016-12-01

    Full Text Available L’enseignement supérieur traditionnel est essentiellement basé sur la transmission du savoir et occasionnellement sur celle du savoir-faire. Il se réclame donc des disciplines universitaires (mathématiques, physique, chimie, géologie.... dispensées dans les universités et grandes écoles. Or, la réussite professionnelle et sociale dans le monde moderne exige d’autres acquis plus probants que des connaissances pures. Plusieurs recherches récentes ont ainsi montré que la résolution de bien des problèmes requiert des qualités pragmatiques d’efficacité indispensables pour l’accomplissement d’un travail créatif. Résoudre un problème revient alors à apprendre à maitriser une démarche méthodique composée de plusieurs phases, depuis l’identification du problème jusqu’à sa solution finale en passant par l’analyse judicieuse des causes. Il faut également maîtriser l’utilisation d’outils conceptuels et Méthodologiques tels que, entre autres, la « loi de Pareto », le questionnement systématique et le brainstorming . Au Vietnam on peut espérer la mise en application de ces nouvelles orientations dans un enseignement supérieur qui doit absolument se fixer comme objectif d’améliorer la qualité du travail social pour répondre aux nouvelles exigences de développement du pays.

  3. Etude de la formation de resonances electroniques et de leur role dans la fragmentation neutre de molecules d'interet biologique

    Science.gov (United States)

    Lepage, Martin

    1998-12-01

    Cette these est presentee a la Faculte de medecine de l'Universite de Sherbrooke en vue de l'obtention du grade de Ph.D. en Radiobiologie. Elle contient des resultats experimentaux enregistres avec un spectrometre d'electrons a haute resolution. Ces resultats portent sur la formation de resonances electroniques en phase condensee et de differents canaux pour leur decroissance. En premier lieu, nous presentons des mesures d'excitations vibrationnelles de l'oxygene dilue en matrice d'argon pour des energies des electrons incidents de 1 a 20 eV. Les resultats suggerent que le temps de vie des resonances de l'oxygene est modifie par la densite d'etats d'electrons dans la bande de conduction de l'argon. Nous presentons aussi des spectres de pertes d'energie d'electrons des molecules de tetrahydrofuranne (THF) et d'acetone. Dans les deux cas, la position en energie des pertes associees aux excitations vibrationnelles est en excellent accord avec les resultats trouves dans la litterature. Les fonctions d'excitation de ces modes revelent la presence de plusieurs nouvelles resonances electroniques. Nous comparons les resonances du THF et celles de la molecule de cyclopentane en phase gazeuse. Nous proposons une origine commune aux resonances ce qui implique qu'elles ne sont pas necessairement attribuees a l'excitation des electrons non-apparies de l'oxygene du THF. Nous proposons une nouvelle methode basee sur la spectroscopie par pertes d'energie des electrons pour detecter la production de fragments neutres qui demeurent a l'interieur d'un film mince condense a basse temperature. Cette methode se base sur la detection des excitations electroniques du produit neutre. Nous presentons des resultats de la production de CO dans un film de methanol. Le taux de production de CO en fonction de l'energie incidente des electrons est calibre en termes d'une section efficace totale de diffusion des electrons. Les resultats indiquent une augmentation lineaire du taux de production de

  4. Cavity sideband cooling of trapped molecules

    NARCIS (Netherlands)

    Kowalewski, Markus; Morigi, Giovanna; Pinkse, Pepijn Willemszoon Harry; de Vivie-Riedle, Regina

    2011-01-01

    The efficiency of cavity sideband cooling of trapped molecules is theoretically investigated for the case in which the infrared transition between two rovibrational states is used as a cycling transition. The molecules are assumed to be trapped either by a radiofrequency or optical trapping

  5. Hydrogen storage by polylithiated molecules and nanostructures

    NARCIS (Netherlands)

    Er, S.; de Wijs, Gilles A.; Brocks, G.

    2009-01-01

    We study polylithiated molecules as building blocks for hydrogen storage materials, using first-principles calculations. CLi4 and OLi2 bind 12 and 10 hydrogen molecules, respectively, with an average binding energy of 0.10 and 0.13 eV, leading to gravimetric densities of 37.8 and 40.3 wt % of H2.

  6. Transport through a Single Octanethiol Molecule

    NARCIS (Netherlands)

    Kockmann, D.; Poelsema, Bene; Zandvliet, Henricus J.W.

    2009-01-01

    Octanethiol molecules adsorbed on Pt chains are studied with scanning tunneling microscopy and spectroscopy at 77 K. The head of the octanethiol binds to a Pt atom and the tail is lying flat down on the chain. Open-loop current time traces reveal that the molecule wags its tail and attaches to the

  7. The First Quantum Theory of Molecules

    Indian Academy of Sciences (India)

    IAS Admin

    rotational energies of diatomic molecules. That theory was ... resent the intensity of light emitted by a black body as a function of ... by the vibrational motion of its parts”. Bjerrum was .... −1/4; despite the fact that no molecule is a rigid rotor,.

  8. The MHC molecules of nonmammalian vertebrates

    DEFF Research Database (Denmark)

    Kaufman, J; Skjoedt, K; Salomonsen, J

    1990-01-01

    class II distribution. The axolotl has a very poor immune response (as though there are no helper T cells), a wide class II distribution and, for most animals, no cell surface class I molecule. It would be enlightening to understand both the mechanisms for the regulation of the MHC molecules during...

  9. Controlled contact to a C-60 molecule

    DEFF Research Database (Denmark)

    Neel, N.; Kröger, J.; Limot, L.

    2007-01-01

    The tip of a low-temperature scanning tunneling microscope is approached towards a C-60 molecule adsorbed at a pentagon-hexagon bond on Cu(100) to form a tip-molecule contact. The conductance rapidly increases to approximate to 0.25 conductance quanta in the transition region from tunneling to co...

  10. Multiple photon infrared processes in polyatomic molecules

    International Nuclear Information System (INIS)

    Harrison, R.G.; Butcher, S.R.

    1980-01-01

    This paper reviews current understanding of the process of multiple photon excitation and dissociation of polyatomic molecules, whereby in the presence of an intense infrared laser field a molecule may absorb upwards of 30 photons. The application of this process to new photochemistry and in particular laser isotope separation is also discussed. (author)

  11. Molecule-oriented programming in Java

    NARCIS (Netherlands)

    Bergstra, J.A.

    2002-01-01

    Molecule-oriented programming is introduced as a programming style carrying some perspective for Java. A sequence of examples is provided. Supporting the development of the molecule-oriented programming style several matters are introduced and developed: profile classes allowing the representation

  12. A prototype storage ring for neutral molecules

    NARCIS (Netherlands)

    Crompvoets, F. M. H.; Bethlem, H. L.; Jongma, R.T.; Meijer, G.

    2001-01-01

    The ability to cool and manipulate atoms with light has yielded atom interferometry, precision spectroscopy, Bose-Einstein condensates and atom lasers. The extension of controlled manipulation to molecules is expected to be similarly rewarding, but molecules are not as amenable to manipulation by

  13. A storage ring for neutral molecules

    NARCIS (Netherlands)

    Crompvoets, F.M.H.

    2005-01-01

    Time-varying inhomogeneous electric fields can be used to manipulate the motion of neutral molecules in phase-space, i.e., position-momentum space, via their electric dipole moment. A theoretical background is given on the motion of the molecules in phase-space. As the forces exerted on the

  14. Extracting Models in Single Molecule Experiments

    Science.gov (United States)

    Presse, Steve

    2013-03-01

    Single molecule experiments can now monitor the journey of a protein from its assembly near a ribosome to its proteolytic demise. Ideally all single molecule data should be self-explanatory. However data originating from single molecule experiments is particularly challenging to interpret on account of fluctuations and noise at such small scales. Realistically, basic understanding comes from models carefully extracted from the noisy data. Statistical mechanics, and maximum entropy in particular, provide a powerful framework for accomplishing this task in a principled fashion. Here I will discuss our work in extracting conformational memory from single molecule force spectroscopy experiments on large biomolecules. One clear advantage of this method is that we let the data tend towards the correct model, we do not fit the data. I will show that the dynamical model of the single molecule dynamics which emerges from this analysis is often more textured and complex than could otherwise come from fitting the data to a pre-conceived model.

  15. Molecules cooled below the Doppler limit

    Science.gov (United States)

    Truppe, S.; Williams, H. J.; Hambach, M.; Caldwell, L.; Fitch, N. J.; Hinds, E. A.; Sauer, B. E.; Tarbutt, M. R.

    2017-12-01

    Magneto-optical trapping and sub-Doppler cooling have been essential to most experiments with quantum degenerate gases, optical lattices, atomic fountains and many other applications. A broad set of new applications await ultracold molecules, and the extension of laser cooling to molecules has begun. A magneto-optical trap (MOT) has been demonstrated for a single molecular species, SrF, but the sub-Doppler temperatures required for many applications have not yet been reached. Here we demonstrate a MOT of a second species, CaF, and we show how to cool these molecules to 50 μK, well below the Doppler limit, using a three-dimensional optical molasses. These ultracold molecules could be loaded into optical tweezers to trap arbitrary arrays for quantum simulation, launched into a molecular fountain for testing fundamental physics, and used to study collisions and chemistry between atoms and molecules at ultracold temperatures.

  16. Cold guided beams of polar molecules

    International Nuclear Information System (INIS)

    Motsch, Michael

    2010-01-01

    This thesis reports on experiments characterizing cold guided beams of polar molecules which are produced by electrostatic velocity filtering. This filtering method exploits the interaction between the polar molecules and the electric field provided by an electrostatic quadrupole guide to extract efficiently the slow molecules from a thermal reservoir. For molecules with large and linear Stark shifts such as deuterated ammonia (ND 3 ) or formaldehyde (H 2 CO), fluxes of guided molecules of 10 10 -10 11 molecules/s are produced. The velocities of the molecules in these beams are in the range of 10-200 m/s and correspond to typical translational temperatures of a few Kelvin. The maximum velocity of the guided molecules depends on the Stark shift, the molecular mass, the geometry of the guide, and the applied electrode voltage. Although the source is operated in the near-effusive regime, the number density of the slowest molecules is sensitive to collisions. A theoretical model, taking into account this velocity-dependent collisional loss of molecules in the vicinity of the nozzle, reproduces the density of the guided molecules over a wide pressure range. A careful adjustment of pressure allows an increase in the total number of molecules, whilst yet minimizing losses due to collisions of the sought-for slow molecules. This is an important issue for future applications. Electrostatic velocity filtering is suited for different molecular species. This is demonstrated by producing cold guided beams of the water isotopologs H 2 O, D 2 O, and HDO. Although these are chemically similar, they show linear and quadratic Stark shifts, respectively, when exposed to external electric fields. As a result, the flux of HDO is larger by one order of magnitude, and the flux of the individual isotopologs shows a characteristic dependence on the guiding electric field. The internal-state distribution of guided molecules is studied with a newly developed diagnostic method: depletion

  17. Single Molecule Spectroscopy of Electron Transfer

    International Nuclear Information System (INIS)

    Holman, Michael; Zang, Ling; Liu, Ruchuan; Adams, David M.

    2009-01-01

    The objectives of this research are threefold: (1) to develop methods for the study electron transfer processes at the single molecule level, (2) to develop a series of modifiable and structurally well defined molecular and nanoparticle systems suitable for detailed single molecule/particle and bulk spectroscopic investigation, (3) to relate experiment to theory in order to elucidate the dependence of electron transfer processes on molecular and electronic structure, coupling and reorganization energies. We have begun the systematic development of single molecule spectroscopy (SMS) of electron transfer and summaries of recent studies are shown. There is a tremendous need for experiments designed to probe the discrete electronic and molecular dynamic fluctuations of single molecules near electrodes and at nanoparticle surfaces. Single molecule spectroscopy (SMS) has emerged as a powerful method to measure properties of individual molecules which would normally be obscured in ensemble-averaged measurement. Fluctuations in the fluorescence time trajectories contain detailed molecular level statistical and dynamical information of the system. The full distribution of a molecular property is revealed in the stochastic fluctuations, giving information about the range of possible behaviors that lead to the ensemble average. In the case of electron transfer, this level of understanding is particularly important to the field of molecular and nanoscale electronics: from a device-design standpoint, understanding and controlling this picture of the overall range of possible behaviors will likely prove to be as important as designing ia the ideal behavior of any given molecule.

  18. Stability of matter-antimatter molecules

    International Nuclear Information System (INIS)

    Wong, Cheuk-Yin; Lee, Teck-Ghee

    2011-01-01

    Highlights: → We examine stability of matter-antimatter molecules with four constituents. → The binding of matter-antimatter molecules is a common phenomenon. → Molecules have bound states if ratio of constituent masses greater than ∼4. → We evaluate molecular binding energies and annihilation lifetimes. - Abstract: We examine the stability of matter-antimatter molecules by reducing the four-body problem into a simpler two-body problem with residual interactions. We find that matter-antimatter molecules with constituents (m 1 + ,m 2 - ,m-bar 2 + ,m-bar 1 - ) possess bound states if their constituent mass ratio m 1 /m 2 is greater than about 4. This stability condition suggests that the binding of matter-antimatter molecules is a rather common phenomenon. We evaluate the binding energies and eigenstates of matter-antimatter molecules (μ + e - )-(e + μ - ),(π + e - )-(e + π - ),(K + e - )-(e + K - ),(pe - )-(e + p-bar),(pμ - )-(μ + p-bar), and (K + μ - ) - (μ + K - ), which satisfy the stability condition. We estimate the molecular annihilation lifetimes in their s states.

  19. Single molecule microscopy and spectroscopy: concluding remarks.

    Science.gov (United States)

    van Hulst, Niek F

    2015-01-01

    Chemistry is all about molecules: control, synthesis, interaction and reaction of molecules. All too easily on a blackboard, one draws molecules, their structures and dynamics, to create an insightful picture. The dream is to see these molecules in reality. This is exactly what "Single Molecule Detection" provides: a look at molecules in action at ambient conditions; a breakthrough technology in chemistry, physics and biology. Within the realms of the Royal Society of Chemistry, the Faraday Discussion on "Single Molecule Microscopy and Spectroscopy" was a very appropriate topic for presentation, deliberation and debate. Undoubtedly, the Faraday Discussions have a splendid reputation in stimulating scientific debates along the traditions set by Michael Faraday. Interestingly, back in the 1830's, Faraday himself pursued an experiment that led to the idea that atoms in a compound were joined by an electrical component. He placed two opposite electrodes in a solution of water containing a dissolved compound, and observed that one of the elements of the compound accumulated on one electrode, while the other was deposited on the opposite electrode. Although Faraday was deeply opposed to atomism, he had to recognize that electrical forces were responsible for the joining of atoms. Probably a direct view on the atoms or molecules in his experiment would have convinced him. As such, Michael Faraday might have liked the gathering at Burlington House in September 2015 (). Surely, with the questioning eyes of his bust on the 1st floor corridor, the non-believer Michael Faraday has incited each passer-by to enter into discussion and search for deeper answers at the level of single molecules. In these concluding remarks, highlights of the presented papers and discussions are summarized, complemented by a conclusion on future perspectives.

  20. Etude de la cristallisation d’une nouvelle molécule à efficacité cardiotonique dans un mélange liquide ionique - eau

    OpenAIRE

    Resende de Azevedo , Jacqueline

    2014-01-01

    The anti-solvent crystallization allows obtaining micro/nanoparticles, but it presents some disadvantages. In the case of new pharmaceutical molecules, as the LASSBio-294, the solubility in water or organic solvents is very low limiting the application of this operation. The use of Ionic Liquids (ILs) as alternative solvents opens new perspectives in pharmaceutical processing through anti-solvent crystallization process. Unlike conventional solvents, ILs are entirely composed of ions. ILs are...

  1. Detecting high-density ultracold molecules using atom–molecule collision

    International Nuclear Information System (INIS)

    Chen, Jun-Ren; Kao, Cheng-Yang; Chen, Hung-Bin; Liu, Yi-Wei

    2013-01-01

    Utilizing single-photon photoassociation, we have achieved ultracold rubidium molecules with a high number density that provides a new efficient approach toward molecular quantum degeneracy. A new detection mechanism for ultracold molecules utilizing inelastic atom–molecule collision is demonstrated. The resonant coupling effect on the formation of the X 1 Σ + g ground state 85 Rb 2 allows for a sufficient number of more deeply bound ultracold molecules, which induced an additional trap loss and heating of the co-existing atoms owing to the inelastic atom–molecule collision. Therefore, after the photoassociation process, the ultracold molecules can be investigated using the absorption image of the ultracold rubidium atoms mixed with the molecules in a crossed optical dipole trap. The existence of the ultracold molecules was then verified, and the amount of accumulated molecules was measured. This method detects the final produced ultracold molecules, and hence is distinct from the conventional trap loss experiment, which is used to study the association resonance. It is composed of measurements of the time evolution of an atomic cloud and a decay model, by which the number density of the ultracold 85 Rb 2 molecules in the optical trap was estimated to be >5.2 × 10 11 cm −3 . (paper)

  2. Nano-manipulation of single DNA molecules

    International Nuclear Information System (INIS)

    Hu Jun; Shanghai Jiaotong Univ., Shanghai; Lv Junhong; Wang Guohua; Wang Ying; Li Minqian; Zhang Yi; Li Bin; Li Haikuo; An Hongjie

    2004-01-01

    Nano-manipulation of single atoms and molecules is a critical technique in nanoscience and nanotechnology. This review paper will focus on the recent development of the manipulation of single DNA molecules based on atomic force microscopy (AFM). Precise manipulation has been realized including varied manipulating modes such as 'cutting', 'pushing', 'folding', 'kneading', 'picking up', 'dipping', etc. The cutting accuracy is dominated by the size of the AFM tip, which is usually 10 nm or less. Single DNA fragments can be cut and picked up and then amplified by single molecule PCR. Thus positioning isolation and sequencing can be performed. (authors)

  3. H2 molecules and the intercloud medium

    International Nuclear Information System (INIS)

    Hill, J.K.; Hollenbach, D.J.

    1976-01-01

    We discuss expected column of densities of H 2 in the intercloud medium and the possible use of molecules as indicators of intercloud physical conditions. We treat molecule formation by the H - process and on graphite grains and show that the Barlow-Silk hypothesis of a 1 eV semichemical hydrogen-graphite bond leads to a large enhancement of the intercloud molecule formation rate. Rotational excitation calculations are presented for both cloud and intercloud conditions which show, in agreement with Jura, that the presently observed optically thin H 2 absorption components are more likely to originate in cold clouds than in the intercloud medium

  4. Tunable optical absorption in silicene molecules

    KAUST Repository

    Mokkath, Junais Habeeb; Schwingenschlö gl, Udo

    2016-01-01

    Two-dimensional materials with a tunable band gap that covers a wide range of the solar spectrum hold great promise for sunlight harvesting. For this reason, we investigate the structural, electronic, and optical properties of silicene molecules using time dependent density functional theory. We address the influence of the molecular size, buckling, and charge state as well as that of a dielectric environment. Unlike planar graphene molecules, silicene molecules prefer to form low-buckled structures with strong visible to ultraviolet optical response. We also identify molecular plasmons.

  5. Single Molecule Biophysics Experiments and Theory

    CERN Document Server

    Komatsuzaki, Tamiki; Takahashi, Satoshi; Yang, Haw; Silbey, Robert J; Rice, Stuart A; Dinner, Aaron R

    2011-01-01

    Discover the experimental and theoretical developments in optical single-molecule spectroscopy that are changing the ways we think about molecules and atoms The Advances in Chemical Physics series provides the chemical physics field with a forum for critical, authoritative evaluations of advances in every area of the discipline. This latest volume explores the advent of optical single-molecule spectroscopy, and how atomic force microscopy has empowered novel experiments on individual biomolecules, opening up new frontiers in molecular and cell biology and leading to new theoretical approaches

  6. Tunable optical absorption in silicene molecules

    KAUST Repository

    Mokkath, Junais Habeeb

    2016-07-13

    Two-dimensional materials with a tunable band gap that covers a wide range of the solar spectrum hold great promise for sunlight harvesting. For this reason, we investigate the structural, electronic, and optical properties of silicene molecules using time dependent density functional theory. We address the influence of the molecular size, buckling, and charge state as well as that of a dielectric environment. Unlike planar graphene molecules, silicene molecules prefer to form low-buckled structures with strong visible to ultraviolet optical response. We also identify molecular plasmons.

  7. Molecular Wring Resonances in Chain Molecules

    DEFF Research Database (Denmark)

    Bohr, Henrik; Brunak, Søren; Bohr, Jakob

    1997-01-01

    It is shown that the eigenfrequency of collective twist excitations in chain molecules can be in the megahertz and gigahertz range. Accordingly, resonance states can be obtained at specific frequencies, and phenomena that involve structural properties can take place. Chain molecules can alter the...... their conformation and their ability to function, and a breaking of the chain can result. It is suggested that this phenomenon forms the basis for effects caused by the interaction of microwaves and biomolecules, e.g. microwave assisted hydrolysis of chain molecules....

  8. Aligning molecules with intense nonresonant laser fields

    DEFF Research Database (Denmark)

    Larsen, J.J.; Safvan, C.P.; Sakai, H.

    1999-01-01

    Molecules in a seeded supersonic beam are aligned by the interaction between an intense nonresonant linearly polarized laser field and the molecular polarizability. We demonstrate the general applicability of the scheme by aligning I2, ICl, CS2, CH3I, and C6H5I molecules. The alignment is probed...... by mass selective two dimensional imaging of the photofragment ions produced by femtosecond laser pulses. Calculations on the degree of alignment of I2 are in good agreement with the experiments. We discuss some future applications of laser aligned molecules....

  9. Nouvelles approches en theorie du champ moyen dynamique: le cas du pouvoir thermoelectrique et celui de l'effet orbital d'un champ magnetique

    Science.gov (United States)

    Arsenault, Louis-Francois

    , cette approche donne une bonne representation de S lorsque le systeme devient coherent. Les calculs montrent aussi que la formule Kelvin est precise lorsque la fonction spectrale des electrons devient incoherente, soit a plus haute temperature. Dans la limite Kelvin, S est essentiellement l'entropie par particule, tel que propose il y a longtemps. Nos resultats demontrent ainsi que la vision purement entropique de S est la bonne dans le regime incoherent, alors que dans le regime coherent, l'approche a frequence infinie est meilleure. Nous avons utilise une methode a la fine pointe, soit le Monte-Carlo quantique en temps continu pour resoudre la DMFT. Pour permettre une exploration rapide du diagramme de phase, nous avons du developper une nouvelle version de la methode des perturbations iterees pour qu'elle soit applicable aussi a forte interaction au-dela de la valeur critique de la transition de Mott. Un autre sujet a aussi ete aborde. L'effet orbital du champ magnetique dans les systemes electroniques fortement correles est une question tres importante et peu developpee. Cela est d'autant plus essentiel depuis la decouverte des oscillations quantiques dans les supraconducteurs a haute temperature (haut- Tc). Par desir de developper une methode la moins biaisee possible, nous avons derive la DMFT lorsqu'un champ se couplant a l'operateur energie cinetique par la substitution de Peierls est present. Ce type d'approche est necessaire pour comprendre entre autres l'effet de la physique de Mott sur des phenomenes tels que les oscillations quantiques. Nous avons obtenu un resultat tres important en demontrant rigoureusement que la relation d'auto-coherence de la DMFT et le systeme intermediaire d'impurete quantique restent les memes. L'effet du champ peut etre contenu dans la fonction de Green locale, ce qui constitue la grande difference avec le cas habituel. Ceci permet de continuer a utiliser les solutionneurs d'impuretes standards, qui sont de plus en plus puissants

  10. Interactions of electrons with biologically important molecules

    International Nuclear Information System (INIS)

    Pisklova, K.; Papp, P.; Stano, M.

    2012-01-01

    For the study of interactions of low-energy electrons with the molecules in the gas phase, the authors used electron-molecule cross-beam apparatus. The experiment is carried out in high vacuum, where molecules of the tested compound are inducted through a capillary. For purposes of this experiment the sample was electrically heated to 180 Deg C., giving a bundle of GlyGly molecules into the gas phase. The resulting signals can be evaluated in two different modes: mass spectrum - at continuous electron energy (e.g. 100 eV) they obtained the signal of intensity of the ions according to their mass to charge ratio; ionization and resonance spectra - for selected ion mass when the authors received the signal of intensity of the ions, depending on the energy of interacting electron.

  11. Molecules decreasing the amount of wastes

    International Nuclear Information System (INIS)

    Grumberg, P.

    1993-01-01

    This popularization paper reviews the separation of actinides from radioactive wastes by molecules such as crown ethers to reduce storage and the use of amides instead of TBP to reduce secondary wastes produced by combustion

  12. Final Report: Cooling Molecules with Laser Light

    International Nuclear Information System (INIS)

    Di Rosa, Michael D.

    2012-01-01

    Certain diatomic molecules are disposed to laser cooling in the way successfully applied to certain atoms and that ushered in a revolution in ultracold atomic physics, an identification first made at Los Alamos and which took root during this program. Despite their manipulation into numerous achievements, atoms are nonetheless mundane denizens of the quantum world. Molecules, on the other hand, with their internal degrees of freedom and rich dynamical interplay, provide considerably more complexity. Two main goals of this program were to demonstrate the feasibility of laser-cooling molecules to the same temperatures as laser-cooled atoms and introduce a means for collecting laser-cooled molecules into dense ensembles, a foundational start of studies and applications of ultracold matter without equivalence in atomic systems.

  13. Stochastic Models of Molecule Formation on Dust

    Science.gov (United States)

    Charnley, Steven; Wirstroem, Eva

    2011-01-01

    We will present new theoretical models for the formation of molecules on dust. The growth of ice mantles and their layered structure is accounted for and compared directly to observations through simulation of the expected ice absorption spectra

  14. Biological mechanisms, one molecule at a time

    Science.gov (United States)

    Tinoco, Ignacio; Gonzalez, Ruben L.

    2011-01-01

    The last 15 years have witnessed the development of tools that allow the observation and manipulation of single molecules. The rapidly expanding application of these technologies for investigating biological systems of ever-increasing complexity is revolutionizing our ability to probe the mechanisms of biological reactions. Here, we compare the mechanistic information available from single-molecule experiments with the information typically obtained from ensemble studies and show how these two experimental approaches interface with each other. We next present a basic overview of the toolkit for observing and manipulating biology one molecule at a time. We close by presenting a case study demonstrating the impact that single-molecule approaches have had on our understanding of one of life's most fundamental biochemical reactions: the translation of a messenger RNA into its encoded protein by the ribosome. PMID:21685361

  15. Small molecule probes for cellular death machines.

    Science.gov (United States)

    Li, Ying; Qian, Lihui; Yuan, Junying

    2017-08-01

    The past decade has witnessed a significant expansion of our understanding about the regulated cell death mechanisms beyond apoptosis. The application of chemical biological approaches had played a major role in driving these exciting discoveries. The discovery and use of small molecule probes in cell death research has not only revealed significant insights into the regulatory mechanism of cell death but also provided new drug targets and lead drug candidates for developing therapeutics of human diseases with huge unmet need. Here, we provide an overview of small molecule modulators for necroptosis and ferroptosis, two non-apoptotic cell death mechanisms, and discuss the molecular pathways and relevant pathophysiological mechanisms revealed by the judicial applications of such small molecule probes. We suggest that the development and applications of small molecule probes for non-apoptotic cell death mechanisms provide an outstanding example showcasing the power of chemical biology in exploring novel biological mechanisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. On theory of single-molecule transistor

    International Nuclear Information System (INIS)

    Tran Tien Phuc

    2009-01-01

    The results of the study on single-molecule transistor are mainly investigated in this paper. The structure of constructed single-molecule transistor is similar to a conventional MOSFET. The conductive channel of the transistors is a single-molecule of halogenated benzene derivatives. The chemical simulation software CAChe was used to design and implement for the essential parameter of the molecules utilized as the conductive channel. The GUI of Matlab has been built to design its graphical interface, calculate and plot the output I-V characteristic curves for the transistor. The influence of temperature, length and width of the conductive channel, and gate voltage is considered. As a result, the simulated curves are similar to the traditional MOSFET's. The operating temperature range of the transistors is wider compared with silicon semiconductors. The supply voltage for transistors is only about 1 V. The size of transistors in this research is several nanometers.

  17. Kinematic anharmonicity of internal rotation of molecules

    International Nuclear Information System (INIS)

    Bataev, V.A.; Pupyshev, V.I.; Godunov, I.A.

    2017-01-01

    The methods of analysis the strongly coupled vibrations are proposed for a number of molecules of aromatic and heterocyclic carbonyl (and some others) compounds. The qualitative principles are formulated for molecular systems with a significant kinematic anharmonicity.

  18. Analytic vibrational matrix elements for diatomic molecules

    International Nuclear Information System (INIS)

    Bouanich, J.P.; Ogilvie, J.F.; Tipping, R.H.

    1986-01-01

    The vibrational matrix elements and expectation values for a diatomic molecule, including the rotational dependence, are calculated for powers of the reduced displacement in terms of the parameters of the Dunham potential-energy function. (orig.)

  19. Evaluation of magnetic dipolar terms in molecules

    International Nuclear Information System (INIS)

    Muniz, R.B.; Brandi, H.S.; Maffeo, B.

    1977-01-01

    The magnetic dipolar parameter b for several values of the internuclear distance in the molecule F 2 - is evaluated. The difficulties appearing in the calculations are discussed and a manner to overcome them is presented [pt

  20. Multi-Excitonic Quantum Dot Molecules

    Science.gov (United States)

    Scheibner, M.; Stinaff, E. A.; Doty, M. F.; Ware, M. E.; Bracker, A. S.; Gammon, D.; Ponomarev, I. V.; Reinecke, T. L.; Korenev, V. L.

    2006-03-01

    With the ability to create coupled pairs of quantum dots, the next step towards the realization of semiconductor based quantum information processing devices can be taken. However, so far little knowledge has been gained on these artificial molecules. Our photoluminescence experiments on single InAs/GaAs quantum dot molecules provide the systematics of coupled quantum dots by delineating the spectroscopic features of several key charge configurations in such quantum systems, including X, X^+,X^2+, XX, XX^+ (with X being the neutral exciton). We extract general rules which determine the formation of molecular states of coupled quantum dots. These include the fact that quantum dot molecules provide the possibility to realize various spin configurations and to switch the electron hole exchange interaction on and off by shifting charges inside the molecule. This knowledge will be valuable in developing implementations for quantum information processing.

  1. Optics and molecules on atom chips

    International Nuclear Information System (INIS)

    Tscherneck, M; Holmes, M E; Quinto-Su, P A; Haimberger, C; Kleinert, J; Bigelow, N P

    2005-01-01

    In this paper we will report on four experiments which have been carried out in the last year in our group. All of these experiments are necessary steps towards the trapping and probing of ultracold molecules on a chip surface

  2. Coherent Bichromatic Force Deflection of Molecules

    Science.gov (United States)

    Kozyryev, Ivan; Baum, Louis; Aldridge, Leland; Yu, Phelan; Eyler, Edward E.; Doyle, John M.

    2018-02-01

    We demonstrate the effect of the coherent optical bichromatic force on a molecule, the polar free radical strontium monohydroxide (SrOH). A dual-frequency retroreflected laser beam addressing the X˜2Σ+↔A˜2Π1 /2 electronic transition coherently imparts momentum onto a cryogenic beam of SrOH. This directional photon exchange creates a bichromatic force that transversely deflects the molecules. By adjusting the relative phase between the forward and counterpropagating laser beams we reverse the direction of the applied force. A momentum transfer of 70 ℏk is achieved with minimal loss of molecules to dark states. Modeling of the bichromatic force is performed via direct numerical solution of the time-dependent density matrix and is compared with experimental observations. Our results open the door to further coherent manipulation of molecular motion, including the efficient optical deceleration of diatomic and polyatomic molecules with complex level structures.

  3. Electric dipole moment of diatomic molecules

    International Nuclear Information System (INIS)

    Rosato, A.

    1983-01-01

    The electric dipole moment of some diatomic molecules is calculated using the Variational Cellular Method. The results obtained for the molecules CO, HB, HF and LiH are compared with other calculations and with experimental data. It is shown that there is strong dependence of the electric dipole moment with respect to the geometry of the cells. It is discussed the possibility of fixing the geometry of the problem by giving the experimental value of the dipole moment. (Author) [pt

  4. Newly detected molecules in dense interstellar clouds

    Science.gov (United States)

    Irvine, William M.; Avery, L. W.; Friberg, P.; Matthews, H. E.; Ziurys, L. M.

    Several new interstellar molecules have been identified including C2S, C3S, C5H, C6H and (probably) HC2CHO in the cold, dark cloud TMC-1; and the discovery of the first interstellar phosphorus-containing molecule, PN, in the Orion "plateau" source. Further results include the observations of 13C3H2 and C3HD, and the first detection of HCOOH (formic acid) in a cold cloud.

  5. Electron affinities of atoms, molecules, and radicals

    International Nuclear Information System (INIS)

    Christodoulides, A.A.; McCorkle, D.L.; Christophorou, L.G.

    1982-01-01

    We review briefly but comprehensively the theoretical, semiempirical and experimental methods employed to determine electron affinities (EAs) of atoms, molecules and radicals, and summarize the EA data obtained by these methods. The detailed processes underlying the principles of the experimental methods are discussed very briefly. It is, nonetheless, instructive to recapitulate the definition of EA and those of the related quantities, namely, the vertical detachment energy, VDE, and the vertical attachment energy, VAE. The EA of an atom is defined as the difference in total energy between the ground state of the neutral atom (plus the electron at rest at infinity) and its negative ion. The EA of a molecule is defined as the difference in energy between the neutral molecule plus an electron at rest at infinity and the molecular negative ion when both, the neutral molecules and the negative ion, are in their ground electronic, vibrational and rotational states. The VDE is defined as the minimum energy required to eject the electron from the negative ion (in its ground electronic and nuclear state) without changing the internuclear separation; since the vertical transition may leave the neutral molecule in an excited vibrational/rotational state, the VDE, although the same as the EA for atoms is, in general, different (larger than), from the EA for molecules. Similarly, the VAE is defined as the difference in energy between the neutral molecule in its ground electronic, vibrational and rotational states plus an electron at rest at infinity and the molecular negative ion formed by addition of an electron to the neutral molecule without allowing a change in the intermolecular separation of the constituent nuclei; it is a quantity appropriate to those cases where the lowest negative ion state lies above the ground states of the neutral species and is less or equal to EA

  6. Electric dipole moment of diatomic molecules

    International Nuclear Information System (INIS)

    Rosato, A.

    1983-01-01

    The electric dipole moment of some diatomic molecules is calculated using the Variational Cellular Method. The results obtained for the CO, HB, HF and LiH molecules are compared with other calculations and with experimental data. It is shown that there is strong dependence of the electric dipole moment with respect to the geometry of the cells. The possibility of fixing the geometry of the problem by giving the experimental value of the dipole moment is discussed. (Author) [pt

  7. Bitter and sweet tasting molecules: It's complicated.

    Science.gov (United States)

    Di Pizio, Antonella; Ben Shoshan-Galeczki, Yaron; Hayes, John E; Niv, Masha Y

    2018-04-19

    "Bitter" and "sweet" are frequently framed in opposition, both functionally and metaphorically, in regard to affective responses, emotion, and nutrition. This oppositional relationship is complicated by the fact that some molecules are simultaneously bitter and sweet. In some cases, a small chemical modification, or a chirality switch, flips the taste from sweet to bitter. Molecules humans describe as bitter are recognized by a 25-member subfamily of class A G-protein coupled receptors (GPCRs) known as TAS2Rs. Molecules humans describe as sweet are recognized by a TAS1R2/TAS1R3 heterodimer of class C GPCRs. Here we characterize the chemical space of bitter and sweet molecules: the majority of bitter compounds show higher hydrophobicity compared to sweet compounds, while sweet molecules have a wider range of sizes. Importantly, recent evidence indicates that TAS1Rs and TAS2Rs are not limited to the oral cavity; moreover, some bitterants are pharmacologically promiscuous, with the hERG potassium channel, cytochrome P450 enzymes, and carbonic anhydrases as common off-targets. Further focus on polypharmacology may unravel new physiological roles for tastant molecules. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Sol-gel method for encapsulating molecules

    Science.gov (United States)

    Brinker, C. Jeffrey; Ashley, Carol S.; Bhatia, Rimple; Singh, Anup K.

    2002-01-01

    A method for encapsulating organic molecules, and in particular, biomolecules using sol-gel chemistry. A silica sol is prepared from an aqueous alkali metal silicate solution, such as a mixture of silicon dioxide and sodium or potassium oxide in water. The pH is adjusted to a suitably low value to stabilize the sol by minimizing the rate of siloxane condensation, thereby allowing storage stability of the sol prior to gelation. The organic molecules, generally in solution, is then added with the organic molecules being encapsulated in the sol matrix. After aging, either a thin film can be prepared or a gel can be formed with the encapsulated molecules. Depending upon the acid used, pH, and other processing conditions, the gelation time can be from one minute up to several days. In the method of the present invention, no alcohols are generated as by-products during the sol-gel and encapsulation steps. The organic molecules can be added at any desired pH value, where the pH value is generally chosen to achieve the desired reactivity of the organic molecules. The method of the present invention thereby presents a sufficiently mild encapsulation method to retain a significant portion of the activity of the biomolecules, compared with the activity of the biomolecules in free solution.

  9. Free and binary rotation of polyatomic molecules

    International Nuclear Information System (INIS)

    Konyukhov, V K

    2003-01-01

    A modification of the quantum-mechanical theory of rotation of polyatomic molecules (binary rotation) is proposed, which is based on the algebra and representations of the SO(4) group and allows the introduction of the concept of parity, as in atomic spectroscopy. It is shown that, if an asymmetric top molecule performing binary rotation finds itself in a spatially inhomogeneous electric field, its rotational levels acquire the additional energy due to the quadrupole moment. The existence of the rotational states of polyatomic molecules that cannot transfer to the free rotation state is predicted. In particular, the spin isomers of a water molecule, which corresponds to such states, can have different absolute values of the adsorption energy due to the quadrupole interaction of the molecule with a surface. The difference in the adsorption energies allows one to explain qualitatively the behaviour of the ortho- and para-molecules of water upon their adsorption on the surface of solids in accordance with experimental data. (laser applications and other topics in quantum electronics)

  10. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Lu, H. Peter [Bowling Green State Univ., Bowling Green, OH (United States). Dept. of Chemistry and Center for Photochemical Sciences

    2017-11-28

    This project is focused on the use of single-molecule high spatial and temporal resolved techniques to study molecular dynamics in condensed phase and at interfaces, especially, the complex reaction dynamics associated with electron and energy transfer rate processes. The complexity and inhomogeneity of the interfacial ET dynamics often present a major challenge for a molecular level comprehension of the intrinsically complex systems, which calls for both higher spatial and temporal resolutions at ultimate single-molecule and single-particle sensitivities. Combined single-molecule spectroscopy and electrochemical atomic force microscopy approaches are unique for heterogeneous and complex interfacial electron transfer systems because the static and dynamic inhomogeneities can be identified and characterized by studying one molecule at a specific nanoscale surface site at a time. The goal of our project is to integrate and apply these spectroscopic imaging and topographic scanning techniques to measure the energy flow and electron flow between molecules and substrate surfaces as a function of surface site geometry and molecular structure. We have been primarily focusing on studying interfacial electron transfer under ambient condition and electrolyte solution involving both single crystal and colloidal TiO2 and related substrates. The resulting molecular level understanding of the fundamental interfacial electron transfer processes will be important for developing efficient light harvesting systems and broadly applicable to problems in fundamental chemistry and physics. We have made significant advancement on deciphering the underlying mechanism of the complex and inhomogeneous interfacial electron transfer dynamics in dyesensitized TiO2 nanoparticle systems that strongly involves with and regulated by molecule-surface interactions. We have studied interfacial electron transfer on TiO2 nanoparticle surfaces by using ultrafast single-molecule

  11. Nouvelles applications des insaponifiables et des lipides de synthèse d’origine végétale en dermocosmétique

    Directory of Open Access Journals (Sweden)

    Piccardi Nathalie

    2004-11-01

    Full Text Available Lipid chemistry is the main know-how of the research and development Center of Laboratoires Expanscience. Our paper will be focused on this field with special emphasize on three different techniques molecular distillation, bio-enzymatic reaction and green chemistry. Each technique will be illustrated by an active molecule, namely Soline®, 5-_ Avocuta®, Cycloceramide®. The process, composition as well as the efficiency of the product will be presented. These data are illustrated by numerous patents and scientific communications.

  12. Single-Molecule Electronics with Cross- Conjugated Molecules: Quantum Interference, IETS and Non-Equilibrium "Temperatures"

    DEFF Research Database (Denmark)

    Jørgensen, Jacob Lykkebo

    Abstract The idea of using single-molecules as components in electronic devices is fas- cinating. For this idea to come into fruition, a number of technical and theo- retical challenges must be overcome. In this PhD thesis, the electron-phonon interaction is studied for a special class of molecules......, which is characterised by destructive quantum interference. The molecules are cross-conjugated, which means that the two parts of the molecules are conjugated to a third part, but not to each other. This gives rise to an anti-resonance in the trans- mission. In the low bias and low temperature regime......-conjugated molecules. We nd that the vibrational modes that would be expected to dominate, following the propensity, rules are very weak. Instead, other modes are found to be the dominant ones. We study this phenomenon for a number of cross-conjugated molecules, and link these ndings to the anti...

  13. Our Galactic Neighbor Hosts Complex Organic Molecules

    Science.gov (United States)

    Hensley, Kerry

    2018-03-01

    For the first time, data from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal the presence of methyl formate and dimethyl ether in a star-forming region outside our galaxy. This discovery has important implications for the formation and survival of complex organic compounds importantfor the formation of life in low-metallicity galaxies bothyoung and old.No Simple Picture of Complex Molecule FormationALMA, pictured here with the Magellanic Clouds above, has observed organic molecules in our Milky Way Galaxy and beyond. [ESO/C. Malin]Complex organic molecules (those with at least six atoms, one or more of which must be carbon) are the precursors to the building blocks of life. Knowing how and where complex organic molecules can form is a key part of understanding how life came to be on Earth and how it might arise elsewhere in the universe. From exoplanet atmospheres to interstellar space, complex organic molecules are ubiquitous in the Milky Way.In our galaxy, complex organic molecules are often found in the intense environments of hot cores clumps of dense molecular gas surrounding the sites of star formation. However, its not yet fully understood how the complex organic molecules found in hot cores come to be. One possibility is that the compounds condense onto cold dust grains long before the young stars begin heating their natal shrouds. Alternatively, they might assemble themselves from the hot, dense gas surrounding the blazing protostars.Composite infrared and optical image of the N 113 star-forming region in the LMC. The ALMA coverage is indicated by the gray line. Click to enlarge. [Sewio et al. 2018]Detecting Complexity, a Galaxy AwayUsing ALMA, a team of researchers led by Marta Sewio (NASA Goddard Space Flight Center) recently detected two complex organic molecules methyl formate and dimethyl ether for the first time in our neighboring galaxy, the Large Magellanic Cloud (LMC). Previous searches for organic molecules in the LMC detected

  14. New structural studies of liquid crystal by reflectivity and resonant X-ray diffraction; Nouvelles etudes structurales de cristaux liquides par reflectivite et diffraction resonante des rayons X

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, P

    2007-04-15

    This memory presents three structural studies of smectic Liquid Crystals by reflectivity and resonant diffraction of X-rays. It is divided in five chapters. In the first a short introduction to Liquid Crystals is given. In particular, the smectic phases that are the object of this study are presented. The second chapter is consecrated to the X-ray experimental techniques that were used in this work. The three last chapters present the works on which this thesis can be divided. Chapter three demonstrates on free-standing films of MHPOBC (historic liquid crystal that possesses the antiferroelectric sub-phases) the possibility to extend the technique of resonant X-ray diffraction to liquid crystals without resonant element. In the fourth chapter the structure of the B{sub 2} liquid crystal phase of bent-core molecules (or banana molecules) is elucidated by using resonant X-ray diffraction combined with polarization analysis of the diffracted beam. A model of the polarization of the resonant beam diffracted by four different structures proposed for the B{sub 2} phase is developed in this chapter. In the fifth chapter a smectic binary mixture presenting a very original critical point of phase separation is studied by X-ray reflectivity and optical microscopy. A concentration gradient in the direction perpendicular to the plane of the film seems to be induced by the free-standing film geometry. The results of a simplified model of the system are compatible with this interpretation.

  15. Nouvelles formes de gouvernance dans le domaine de l’eau. Apports et limites de la coopération décentralisée dans les pays en développement

    Directory of Open Access Journals (Sweden)

    Raoudha Makkaoui

    2010-09-01

    Full Text Available La problématique de cet article porte sur le rôle de la coopération décentralisée dans le domaine de l’eau, dans la mesure où celle-ci semble pouvoir apporter des réponses concrètes au problème de l’accès universel à l’eau et constituer une nouvelle option pour la communauté internationale. Dans une première partie, on présentera les problèmes rencontrés par les différents modes de gestion de l’eau dans les pays en développement et la façon dont ils ont successivement tenté de satisfaire à certains objectifs bien précis (accès universel à l’eau, réduction des coûts, prise en compte des besoins prioritaires. Dans une deuxième partie, sur la base d’une initiative de coopération décentralisée entre le Conseil régional de Seine-Saint-Denis et la ville marocaine de Figuig, on s’interrogera sur les apports et limites de cette nouvelle forme de partenariat participatif afin d’en évaluer la pérennité ainsi que la « soutenabilité sociale », montrant, de ce fait, sa proximité avec l’économie solidaire.Our paper builds on this issue of decentralized cooperation in the field of water management. Cooperation between decentralized entities in order to ensure the access to safe drinking water for all now constitutes in many places a preferred water governance option. Therefore, in the first part, we will provide an overview of the current difficulties encountered by the various forms of water management in developing countries, showing the solutions that they successively brought to specific issues (access for all, cost reduction, priority needs. In the second part, we will address the particular case of decentralized cooperation between the General Council of Seine-Saint-Denis in the suburbs of Paris, France, in partnership with the city of Figuig in Morocco. We review the insights and limits of such processes that refer to the people’s capabilities, at both individual and collective levels, in

  16. La « Nouvelle Mosquée » d’Alger. Le déroulement d’une procédure constructive au xviie siècle

    Directory of Open Access Journals (Sweden)

    Samia Chergui

    2012-01-01

    Full Text Available « La Nouvelle Mosquée » est érigée, à la fin du xviie siècle, dans la seule perspective de doter le rite hanéfite de sa propre Grande Mosquée. Cette nouvelle édification relève, à l’évidence, d’une procédure collective exceptionnelle, celle qu’entreprend la milice d’Alger, en l’occurrence le corps des janissaires, en puisant dans les fonds des Subul al-Khayrât. L’examen du livre de comptes qu’avait tenu cette institution ḥabûs, responsable de la gestion de la plupart des mosquées hanéfites et de leurs awqâf, aussitôt après le lancement du chantier, a permis de suivre le déroulement des travaux sur une période de presque dix années, soit de 1067/1656-1657 à 1076/1665-1666. Ce rôle de chantier apporte des éclairages significatifs notamment sur la nature, la provenance, la quantité et le coût des matériaux employés à la construction. Ils ne manquent pas non plus de documenter les aspects concernant leur fabrication, voire leur préparation, et quelque rares fois leur mise en œuvre ; une mise en œuvre qui, ici, revient à la dextérité de nombreux hommes, mobilisés dans le cadre corporatif. La comptabilité salariale, tenue en cette occasion, compte d’ailleurs parmi les rares initiatives de gestion qui ont permis, durant au moins une décennie, de consigner les plus amples détails non seulement sur le profil distinctif de l’ensemble de ces intervenants, mais également sur leur origine géographique, voire confessionnelle.

  17. Toward Generalization of Iterative Small Molecule Synthesis.

    Science.gov (United States)

    Lehmann, Jonathan W; Blair, Daniel J; Burke, Martin D

    2018-02-01

    Small molecules have extensive untapped potential to benefit society, but access to this potential is too often restricted by limitations inherent to the customized approach currently used to synthesize this class of chemical matter. In contrast, the "building block approach", i.e., generalized iterative assembly of interchangeable parts, has now proven to be a highly efficient and flexible way to construct things ranging all the way from skyscrapers to macromolecules to artificial intelligence algorithms. The structural redundancy found in many small molecules suggests that they possess a similar capacity for generalized building block-based construction. It is also encouraging that many customized iterative synthesis methods have been developed that improve access to specific classes of small molecules. There has also been substantial recent progress toward the iterative assembly of many different types of small molecules, including complex natural products, pharmaceuticals, biological probes, and materials, using common building blocks and coupling chemistry. Collectively, these advances suggest that a generalized building block approach for small molecule synthesis may be within reach.

  18. Capillary condensation of short-chain molecules.

    Science.gov (United States)

    Bryk, Paweł; Pizio, Orest; Sokolowski, Stefan

    2005-05-15

    A density-functional study of capillary condensation of fluids of short-chain molecules confined to slitlike pores is presented. The molecules are modeled as freely jointed tangent spherical segments with a hard core and with short-range attractive interaction between all the segments. We investigate how the critical parameters of capillary condensation of the fluid change when the pore width decreases and eventually becomes smaller than the nominal linear dimension of the single-chain molecule. We find that the dependence of critical parameters for a fluid of dimers and of tetramers on pore width is similar to that of the monomer fluid. On the other hand, for a fluid of chains consisting of a larger number of segments we observe an inversion effect. Namely, the critical temperature of capillary condensation decreases with increasing pore width for a certain interval of values of the pore width. This anomalous behavior is also influenced by the interaction between molecules and pore walls. We attribute this behavior to the effect of conformational changes of molecules upon confinement.

  19. Toward Generalization of Iterative Small Molecule Synthesis

    Science.gov (United States)

    Lehmann, Jonathan W.; Blair, Daniel J.; Burke, Martin D.

    2018-01-01

    Small molecules have extensive untapped potential to benefit society, but access to this potential is too often restricted by limitations inherent to the customized approach currently used to synthesize this class of chemical matter. In contrast, the “building block approach”, i.e., generalized iterative assembly of interchangeable parts, has now proven to be a highly efficient and flexible way to construct things ranging all the way from skyscrapers to macromolecules to artificial intelligence algorithms. The structural redundancy found in many small molecules suggests that they possess a similar capacity for generalized building block-based construction. It is also encouraging that many customized iterative synthesis methods have been developed that improve access to specific classes of small molecules. There has also been substantial recent progress toward the iterative assembly of many different types of small molecules, including complex natural products, pharmaceuticals, biological probes, and materials, using common building blocks and coupling chemistry. Collectively, these advances suggest that a generalized building block approach for small molecule synthesis may be within reach. PMID:29696152

  20. Stochastic models for surface diffusion of molecules

    Energy Technology Data Exchange (ETDEWEB)

    Shea, Patrick, E-mail: patrick.shea@dal.ca; Kreuzer, Hans Jürgen [Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia B3H 3J5 (Canada)

    2014-07-28

    We derive a stochastic model for the surface diffusion of molecules, starting from the classical equations of motion for an N-atom molecule on a surface. The equation of motion becomes a generalized Langevin equation for the center of mass of the molecule, with a non-Markovian friction kernel. In the Markov approximation, a standard Langevin equation is recovered, and the effect of the molecular vibrations on the diffusion is seen to lead to an increase in the friction for center of mass motion. This effective friction has a simple form that depends on the curvature of the lowest energy diffusion path in the 3N-dimensional coordinate space. We also find that so long as the intramolecular forces are sufficiently strong, memory effects are usually not significant and the Markov approximation can be employed, resulting in a simple one-dimensional model that can account for the effect of the dynamics of the molecular vibrations on the diffusive motion.

  1. Photodissociation and excitation of interstellar molecules

    International Nuclear Information System (INIS)

    Dishoeck, E.F. van.

    1984-01-01

    Apart from a rather long introduction containing some elementary astrophysics, quantum chemistry and spectroscopy and an incomplete, historical review of molecular observations, this thesis is divided into three sections. In part A, a rigorous quantum chemical and dynamical study is made of the photodissociation processes in the OH and HCl molecules. In part B, the cross sections obtained in part A are used in various astrophysical problems such as the study of the abundances of the OH and HCl molecules in interstellar clouds, the use of the OH abundance as a measure of the cosmic ray ionization rate, the lifetime of the OH radical in comets and the abundance of OH in the solar photosphere. Part C discusses the excitation of the C 2 molecule under interstellar conditions, its use as a diagnostic probe of the temperature, density and strength of the radiation field in interstellar clouds. Quadrupole moments and oscillator strengths are analyzed. (Auth.)

  2. Difference Raman spectroscopy of DNA molecules

    International Nuclear Information System (INIS)

    Anokhin, Andrey S; Yuzyuk, Yury I; Gorelik, Vladimir S; Dovbeshko, Galina I; Pyatyshev, Alexander Yu

    2015-01-01

    In this paper the micro-Raman spectra of calf DNA for different points of DNA sample have been recorded. The Raman spectra were made with help of difference Raman spectroscopy technique. Raman spectra were recorded with high spatial resolution from different points of the wet and dry samples in different spectral range (100÷4000cm −1 ) using two lasers: argon (514.5 nm) and helium -neon (632.8 nm). The significant differences in the Raman spectra for dry and wet DNA and for different points of DNA molecules were observed. The obtained data on difference Raman scattering spectra of DNA molecules may be used for identification of DNA types and for analysis of genetic information associated with the molecular structure of this molecule

  3. Torque Measurement at the Single Molecule Level

    Science.gov (United States)

    Forth, Scott; Sheinin, Maxim Y.; Inman, James; Wang, Michelle D.

    2017-01-01

    Methods for exerting and measuring forces on single molecules have revolutionized the study of the physics of biology. However, it is often the case that biological processes involve rotation or torque generation, and these parameters have been more difficult to access experimentally. Recent advances in the single molecule field have led to the development of techniques which add the capability of torque measurement. By combining force, displacement, torque, and rotational data, a more comprehensive description of the mechanics of a biomolecule can be achieved. In this review, we highlight a number of biological processes for which torque plays a key mechanical role. We describe the various techniques that have been developed to directly probe the torque experienced by a single molecule, and detail a variety of measurements made to date using these new technologies. We conclude by discussing a number of open questions and propose systems of study which would be well suited for analysis with torsional measurement techniques. PMID:23541162

  4. Molecule scattering from insulator and metal surfaces

    International Nuclear Information System (INIS)

    Moroz, Iryna; Ambaye, Hailemariam; Manson, J R

    2004-01-01

    Calculations are carried out and compared with data for the scattering of CH 4 molecules from a LiF(001) surface and for O 2 scattering from Al(111). The theory is a mixed classical-quantum formalism that includes energy and momentum transfers between the surface and projectile for translational and rotational motions as well as internal mode excitation of the projectile molecule. The translational and rotational degrees of freedom couple most strongly to multiphonon excitations of the surface and are treated with classical dynamics. Internal vibrational excitations of the molecules are treated with a semiclassical formalism with extension to arbitrary numbers of modes and arbitrary quantum numbers. Calculations show good agreement for the dependence on incident translational energy, incident beam angle and surface temperature when compared with data for energy-resolved intensity spectra and angular distributions

  5. Small molecule inhibitors of anthrax edema factor.

    Science.gov (United States)

    Jiao, Guan-Sheng; Kim, Seongjin; Moayeri, Mahtab; Thai, April; Cregar-Hernandez, Lynne; McKasson, Linda; O'Malley, Sean; Leppla, Stephen H; Johnson, Alan T

    2018-01-15

    Anthrax is a highly lethal disease caused by the Gram-(+) bacteria Bacillus anthracis. Edema toxin (ET) is a major contributor to the pathogenesis of disease in humans exposed to B. anthracis. ET is a bipartite toxin composed of two proteins secreted by the vegetative bacteria, edema factor (EF) and protective antigen (PA). Our work towards identifying a small molecule inhibitor of anthrax edema factor is the subject of this letter. First we demonstrate that the small molecule probe 5'-Fluorosulfonylbenzoyl 5'-adenosine (FSBA) reacts irreversibly with EF and blocks enzymatic activity. We then show that the adenosine portion of FSBA can be replaced to provide more drug-like molecules which are up to 1000-fold more potent against EF relative to FSBA, display low cross reactivity when tested against a panel of kinases, and are nanomolar inhibitors of EF in a cell-based assay of cAMP production. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. RNA as a small molecule druggable target.

    Science.gov (United States)

    Rizvi, Noreen F; Smith, Graham F

    2017-12-01

    Small molecule drugs have readily been developed against many proteins in the human proteome, but RNA has remained an elusive target for drug discovery. Increasingly, we see that RNA, and to a lesser extent DNA elements, show a persistent tertiary structure responsible for many diverse and complex cellular functions. In this digest, we have summarized recent advances in screening approaches for RNA targets and outlined the discovery of novel, drug-like small molecules against RNA targets from various classes and therapeutic areas. The link of structure, function, and small-molecule Druggability validates now for the first time that RNA can be the targets of therapeutic agents. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. Attosecond electron dynamics in molecules and liquids

    Science.gov (United States)

    WöRner, Hans Jakob

    The ultrafast motion of electrons and holes following light-matter interaction is fundamental to a broad range of chemical and biophysical processes. In this lecture, I will discuss some of our recent experiments that measure the atomic-scale motion of charge with attosecond temporal resolution (1 as = 10-18s). The first experiment is carried out on isolated, spatially oriented molecules in the gas phase. Using high-harmonic spectroscopy, we resolve the migration of an electron hole across the molecule with a resolution of 100 as and simultaneously demonstrate extensive control over charge migration. In the second class of experiments, we use an attosecond pulse train synchronized with a near-infrared laser pulse to temporally resolve the process of photoemission from molecules in the gas phase and from a liquid-water microjet, resolving electron transport through liquid water on the attosecond time scale.

  8. Protein Scaffolding for Small Molecule Catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Baker, David [Univ. of Washington, Seattle, WA (United States)

    2014-09-14

    We aim to design hybrid catalysts for energy production and storage that combine the high specificity, affinity, and tunability of proteins with the potent chemical reactivities of small organometallic molecules. The widely used Rosetta and RosettaDesign methodologies will be extended to model novel protein / small molecule catalysts in which one or many small molecule active centers are supported and coordinated by protein scaffolding. The promise of such hybrid molecular systems will be demonstrated with the nickel-phosphine hydrogenase of DuBois et. al.We will enhance the hydrogenase activity of the catalyst by designing protein scaffolds that incorporate proton relays and systematically modulate the local environment of the catalyticcenter. In collaboration with DuBois and Shaw, the designs will be experimentally synthesized and characterized.

  9. A Zeeman slower for diatomic molecules

    Science.gov (United States)

    Petzold, M.; Kaebert, P.; Gersema, P.; Siercke, M.; Ospelkaus, S.

    2018-04-01

    We present a novel slowing scheme for beams of laser-coolable diatomic molecules reminiscent of Zeeman slowing of atomic beams. The scheme results in efficient compression of the one-dimensional velocity distribution to velocities trappable by magnetic or magneto-optical traps. We experimentally demonstrate our method in an atomic testbed and show an enhancement of flux below v = 35 m s‑1 by a factor of ≈20 compared to white light slowing. 3D Monte Carlo simulations performed to model the experiment show excellent agreement. We apply the same simulations to the prototype molecule 88Sr19F and expect 15% of the initial flux to be continuously compressed in a narrow velocity window at around 10 m s‑1. This is the first experimentally shown continuous and dissipative slowing technique in molecule-like level structures, promising to provide the missing link for the preparation of large ultracold molecular ensembles.

  10. Collision data involving hydro-carbon molecules

    International Nuclear Information System (INIS)

    Tawara, H.; Itikawa, Y.; Nishimura, H.; Tanaka, H.; Nakamura, Y.

    1990-07-01

    Hydro-carbon molecules are abundantly produced when graphites are used as internal wall materials of hydrogen plasmas and strongly influence properties of low temperature plasmas near the edges as well as those of high temperature plasmas at the center. In this report, following simple description of the production mechanisms of hydro-carbon molecules under the interactions between graphite and hydrogen plasma, the present status of collision data for hydro-carbon molecules by electron impact is discussed and the relevant data are summarized in a series of figures and tables. It should also be noted that, in addition to fusion plasmas, these hydrocarbon data compiled here are quite useful in other applications such as plasma chemistry and material processing. (author)

  11. Single molecule transcription profiling with AFM

    International Nuclear Information System (INIS)

    Reed, Jason; Mishra, Bud; Pittenger, Bede; Magonov, Sergei; Troke, Joshua; Teitell, Michael A; Gimzewski, James K

    2007-01-01

    Established techniques for global gene expression profiling, such as microarrays, face fundamental sensitivity constraints. Due to greatly increasing interest in examining minute samples from micro-dissected tissues, including single cells, unorthodox approaches, including molecular nanotechnologies, are being explored in this application. Here, we examine the use of single molecule, ordered restriction mapping, combined with AFM, to measure gene transcription levels from very low abundance samples. We frame the problem mathematically, using coding theory, and present an analysis of the critical error sources that may serve as a guide to designing future studies. We follow with experiments detailing the construction of high density, single molecule, ordered restriction maps from plasmids and from cDNA molecules, using two different enzymes, a result not previously reported. We discuss these results in the context of our calculations

  12. Multiphoton processes in isolated atoms and molecules

    International Nuclear Information System (INIS)

    Sudbo, A.S.

    1979-11-01

    The theory of coherent excitation of a multilevel quantum mechanical system is developed. Damping of the system is taken into account by the use of a density matrix formalism. General properties of the wave function and/or the density matrix are discussed. The physical implications for the behavior of the system are described, together with possible applications of the formalism, including the infrared multiphoton excitation of molecules, and optical pumping in alkali atoms. Experimental results are presented on the infrared multiphoton dissociation of molecules, followed by a discussion of the general features of this process. The experimental results were obtained using a crossed laser and molecular beam method, and the emphasis is on determining the properties of the dissociating molecule and the dissociation products. The dissociation process is shown to be described very well by the standard statistical theory (RRKM theory) of unimolecular reactions, a brief presentation of which is also included

  13. Quantum Mechanical Study of Atoms and Molecules

    Science.gov (United States)

    Sahni, R. C.

    1961-01-01

    This paper, following a brief introduction, is divided into five parts. Part I outlines the theory of the molecular orbital method for the ground, ionized and excited states of molecules. Part II gives a brief summary of the interaction integrals and their tabulation. Part III outlines an automatic program designed for the computation of various states of molecules. Part IV gives examples of the study of ground, ionized and excited states of CO, BH and N2 where the program of automatic computation and molecular integrals have been utilized. Part V enlists some special problems of Molecular Quantum Mechanics are being tackled at New York University.

  14. Selective laser photolysis of simple molecules

    International Nuclear Information System (INIS)

    Golnabi, Hossein.

    1984-01-01

    A two-photon technique is reported for the measurement of relative cross section for the photolysis of simple molecules into particular product channels. In this method two independently tunable dye lasers were used to sequentially dissociate molecules of Cs 2 and Cs-Kr for the wavelengths in the range 420 to 660 nm, and then to excite the resulting products to determine the relative cross sections for the photolysis of Cs 2 and Cs-kr into each of the lowest four of the energetically possible product states

  15. Organic molecules with abnormal geometric parameters

    International Nuclear Information System (INIS)

    Komarov, Igor V

    2001-01-01

    Organic molecules, the structural parameters of which (carbon-carbon bond lengths, bond and torsion angles) differ appreciably from the typical most frequently encountered values, are discussed. Using many examples of 'record-breaking' molecules, the limits of structural distortions in carbon compounds and their unusual chemical properties are demonstrated. Particular attention is devoted to strained compounds not yet synthesised whose properties have been predicted using quantum-chemical calculations. Factors that ensure the stability of such compounds are outlined. The bibliography includes 358 references.

  16. Design of small-molecule epigenetic modulators

    Science.gov (United States)

    Pachaiyappan, Boobalan

    2013-01-01

    The field of epigenetics has expanded rapidly to reveal multiple new targets for drug discovery. The functional elements of the epigenomic machinery can be catagorized as writers, erasers and readers, and together these elements control cellular gene expression and homeostasis. It is increasingly clear that aberrations in the epigenome can underly a variety of diseases, and thus discovery of small molecules that modulate the epigenome in a specific manner is a viable approach to the discovery of new therapeutic agents. In this Digest, the components of epigenetic control of gene expression will be briefly summarized, and efforts to identify small molecules that modulate epigenetic processes will be described. PMID:24300735

  17. Molecular spintronics using single-molecule magnets

    Science.gov (United States)

    Bogani, Lapo; Wernsdorfer, Wolfgang

    2008-03-01

    A revolution in electronics is in view, with the contemporary evolution of the two novel disciplines of spintronics and molecular electronics. A fundamental link between these two fields can be established using molecular magnetic materials and, in particular, single-molecule magnets. Here, we review the first progress in the resulting field, molecular spintronics, which will enable the manipulation of spin and charges in electronic devices containing one or more molecules. We discuss the advantages over more conventional materials, and the potential applications in information storage and processing. We also outline current challenges in the field, and propose convenient schemes to overcome them.

  18. Abrupt relaxation in high-spin molecules

    International Nuclear Information System (INIS)

    Chang, C.-R.; Cheng, T.C.

    2000-01-01

    Mean-field model suggests that the rate of resonant quantum tunneling in high-spin molecules is not only field-dependent but also time-dependent. The relaxation-assisted resonant tunneling in high-spin molecules produces an abrupt magnetization change during relaxation. When the applied field is very close to the resonant field, a time-dependent interaction field gradually shifts the energies of different collective spin states, and magnetization tunneling is observed as two energies of the spin states coincide

  19. Raman Optical Activity of Biological Molecules

    Science.gov (United States)

    Blanch, Ewan W.; Barron, Laurence D.

    Now an incisive probe of biomolecular structure, Raman optical activity (ROA) measures a small difference in Raman scattering from chiral molecules in right- and left-circularly polarized light. As ROA spectra measure vibrational optical activity, they contain highly informative band structures sensitive to the secondary and tertiary structures of proteins, nucleic acids, viruses and carbohydrates as well as the absolute configurations of small molecules. In this review we present a survey of recent studies on biomolecular structure and dynamics using ROA and also a discussion of future applications of this powerful new technique in biomedical research.

  20. Hadronic molecules with hidden charm and bottom

    Directory of Open Access Journals (Sweden)

    Guo Feng-Kun

    2016-01-01

    Full Text Available Many of the new structures observed since 2003 in experiments in the heavy quarkonium mass region, such as the X(3872 and Zc (3900, are rather close to certain thresholds, and thus can be good candidates of hadronic molecules, which are loose bound systems of hadrons. We will discuss the consequences of heavy quark symmetry for hadronic molecules with heavy quarks. We will also emphasize that the hadronic molecular component of a given structure can be directly probed in long-distance processes, while the short-distance processes are not sensitive to it.

  1. A Circularly Arranged Sextuple Triptycene Gear Molecule.

    Science.gov (United States)

    Ube, Hitoshi; Yamada, Ryo; Ishida, Jun-Ichi; Sato, Hiroyasu; Shiro, Motoo; Shionoya, Mitsuhiko

    2017-11-22

    Herein we report the synthesis of a circularly arranged sextuple triptycene gear molecule, hexakis(10-dodecyloxy-9-triptycyl)ethynylbenzene, via the trimerization of the corresponding triyne with a cobalt catalyst. The six triptycene gears are closely engaged with each other as confirmed by single crystal X-ray structure analysis, and their motion in solution was established by NMR spectroscopy. Notably, when one bulky RuCp* complex was attached to one triptycene gear, the whole movement of the six gears was highly restricted via their mechanical engagement. Development of such a multigear molecule would provide a structural basis for molecular motion transmission systems with a switching function.

  2. Dissociation of Vertical Semiconductor Diatomic Artificial Molecules

    International Nuclear Information System (INIS)

    Pi, M.; Emperador, A.; Barranco, M.; Garcias, F.; Muraki, K.; Tarucha, S.; Austing, D. G.

    2001-01-01

    We investigate the dissociation of few-electron circular vertical semiconductor double quantum dot artificial molecules at 0T as a function of interdot distance. A slight mismatch introduced in the fabrication of the artificial molecules from nominally identical constituent quantum wells induces localization by offsetting the energy levels in the quantum dots by up to 2meV, and this plays a crucial role in the appearance of the addition energy spectra as a function of coupling strength particularly in the weak coupling limit

  3. Extracellular Molecules Involved in Cancer Cell Invasion

    International Nuclear Information System (INIS)

    Stivarou, Theodora; Patsavoudi, Evangelia

    2015-01-01

    Nowadays it is perfectly clear that understanding and eradicating cancer cell invasion and metastasis represent the crucial, definitive points in cancer therapeutics. During the last two decades there has been a great interest in the understanding of the extracellular molecular mechanisms involved in cancer cell invasion. In this review, we highlight the findings concerning these processes, focusing in particular on extracellular molecules, including extracellular matrix proteins and their receptors, growth factors and their receptors, matrix metalloproteinases and extracellular chaperones. We report the molecular mechanisms underlying the important contribution of this pool of molecules to the complex, multi-step phenomenon of cancer cell invasion

  4. Extracellular Molecules Involved in Cancer Cell Invasion

    Directory of Open Access Journals (Sweden)

    Theodora Stivarou

    2015-01-01

    Full Text Available Nowadays it is perfectly clear that understanding and eradicating cancer cell invasion and metastasis represent the crucial, definitive points in cancer therapeutics. During the last two decades there has been a great interest in the understanding of the extracellular molecular mechanisms involved in cancer cell invasion. In this review, we highlight the findings concerning these processes, focusing in particular on extracellular molecules, including extracellular matrix proteins and their receptors, growth factors and their receptors, matrix metalloproteinases and extracellular chaperones. We report the molecular mechanisms underlying the important contribution of this pool of molecules to the complex, multi-step phenomenon of cancer cell invasion.

  5. Nanoscale methods for single-molecule electrochemistry.

    Science.gov (United States)

    Mathwig, Klaus; Aartsma, Thijs J; Canters, Gerard W; Lemay, Serge G

    2014-01-01

    The development of experiments capable of probing individual molecules has led to major breakthroughs in fields ranging from molecular electronics to biophysics, allowing direct tests of knowledge derived from macroscopic measurements and enabling new assays that probe population heterogeneities and internal molecular dynamics. Although still somewhat in their infancy, such methods are also being developed for probing molecular systems in solution using electrochemical transduction mechanisms. Here we outline the present status of this emerging field, concentrating in particular on optical methods, metal-molecule-metal junctions, and electrochemical nanofluidic devices.

  6. Nonadiabatic transitions in electrostatically trapped ammonia molecules

    International Nuclear Information System (INIS)

    Kirste, Moritz; Schnell, Melanie; Meijer, Gerard; Sartakov, Boris G.

    2009-01-01

    Nonadiabatic transitions are known to be major loss channels for atoms in magnetic traps but have thus far not been experimentally reported upon for trapped molecules. We have observed and quantified losses due to nonadiabatic transitions for three isotopologues of ammonia in electrostatic traps by comparing the trapping times in traps with a zero and a nonzero electric field at the center. Nonadiabatic transitions are seen to dominate the overall loss rate even for the present samples that are at relatively high temperatures of 30 mK. It is anticipated that losses due to nonadiabatic transitions in electric fields are omnipresent in ongoing experiments on cold molecules.

  7. Rare earth(III) complexes for the development of new magnetic and luminescent probes; Complexes de lanthanides(III) pour le developpement de nouvelles sondes magnetiques et luminescentes

    Energy Technology Data Exchange (ETDEWEB)

    Nonat, A

    2007-10-15

    The simultaneous optimisation of the molecular parameters determining the relaxivity (number of coordinated water molecules, water-exchange, rotation dynamics of the whole complex, electronic relaxation, Gd(III)-proton distance) is essential to prepare efficient contrast agents. The aim of this work is on the one hand to design and study complexes with a high number of bound water molecules and to understand the influence of the coordination sphere on the stability and on the electronic relaxation and on the other hand, to use the ligand as a chromophore for the development of luminescent probes for biomedical imaging. We present the structure, the stability and the relaxivity of Gd(III) complexes of two series of tripodal ligands containing picolinate units based either on the 1,4,7-tri-aza-cyclononane ring or on a tertiary amine. These complexes show high relaxivity in water and in serum and can establish a non covalent interaction with serum albumin. The interpretation of the water proton relaxivity with the help of new relaxometric methods based on an auxiliary probe solute has allowed us to show that both the presence of the picolinate groups and the 1,4,7-tri-aza-cyclononane framework can lead to Gd(III) complexes with favourable electronic relaxation properties. This ligands have also been used for Eu(III) and Tb(III) complexation leading to strong luminescence in visible light. Other complexes derived from 8-hydroxyquinoline unit which display a very high luminescence in infrared are also studied. (author)

  8. The origin of small and large molecule behavior in the vibrational relaxation of highly excited molecules

    International Nuclear Information System (INIS)

    Gordon, R.J.

    1990-01-01

    An explanation is proposed for the qualitatively different types of behavior that have been reported for the vibrational relaxation of highly excited diatomic and polyatomic molecules. It is argued that all of the diatomic molecules that have been studied in bulk relax adiabatically at room temperature. In contrast, large polyatomic molecules have low frequency modes which act at ''doorway'' modes for the rest of the molecules, producing an impulsive relaxation mechanism. The theoretical work of Nesbitt and Hynes showed that impulsive collisions result in an exponential decay of the average vibrational energy of a Morse oscillator, whereas adiabatic collisions produce nonexponential power law behavior. We propose that this result explains a large body of data for the vibrational relaxation of small and large molecules

  9. Single Molecule Analysis Research Tool (SMART: an integrated approach for analyzing single molecule data.

    Directory of Open Access Journals (Sweden)

    Max Greenfeld

    Full Text Available Single molecule studies have expanded rapidly over the past decade and have the ability to provide an unprecedented level of understanding of biological systems. A common challenge upon introduction of novel, data-rich approaches is the management, processing, and analysis of the complex data sets that are generated. We provide a standardized approach for analyzing these data in the freely available software package SMART: Single Molecule Analysis Research Tool. SMART provides a format for organizing and easily accessing single molecule data, a general hidden Markov modeling algorithm for fitting an array of possible models specified by the user, a standardized data structure and graphical user interfaces to streamline the analysis and visualization of data. This approach guides experimental design, facilitating acquisition of the maximal information from single molecule experiments. SMART also provides a standardized format to allow dissemination of single molecule data and transparency in the analysis of reported data.

  10. Strategy to discover diverse optimal molecules in the small molecule universe.

    Science.gov (United States)

    Rupakheti, Chetan; Virshup, Aaron; Yang, Weitao; Beratan, David N

    2015-03-23

    The small molecule universe (SMU) is defined as a set of over 10(60) synthetically feasible organic molecules with molecular weight less than ∼500 Da. Exhaustive enumerations and evaluation of all SMU molecules for the purpose of discovering favorable structures is impossible. We take a stochastic approach and extend the ACSESS framework ( Virshup et al. J. Am. Chem. Soc. 2013 , 135 , 7296 - 7303 ) to develop diversity oriented molecular libraries that can generate a set of compounds that is representative of the small molecule universe and that also biases the library toward favorable physical property values. We show that the approach is efficient compared to exhaustive enumeration and to existing evolutionary algorithms for generating such libraries by testing in the NKp fitness landscape model and in the fully enumerated GDB-9 chemical universe containing 3 × 10(5) molecules.

  11. Nouvelle structure de capteur à courants de Foucault et algorithme associé pour la mesure des propriétés électrique et magnétique d'un métal

    Science.gov (United States)

    Lê, Minh-Quang; Placko, Dominique

    1995-06-01

    This paper describes a new structure for eddy-current transducers which improves sensitivity while maintaining high lateral resolution. We have developed an analytical model to allow a model-based inversion from transducers signals to estimate thick and homogeneous plates electrical conductivity, magnetic permeability and/or lift-off. The inversion procedure is described and shows the possibility of a precise simultaneous estimation of the three parameters. Experiments were conducted with magnetic and non magnetic metals. Cet article décrit une nouvelle structure de capteur à courants de Foucault qui permet d'améliorer la sensibilité du capteur tout en conservant sa résolution latérale. Nous avons développé un modèle analytique de ce capteur qui peut être inversé pour estimer la conductivité électrique, la perméabilité magnétique d'une cible homogène et/ou la distance capteur-cible. La procédure d'inversion a été décrite et montre une possibilité d'estimer ces trois paramètres avec précision. L'expérience a été effectuée sur des métaux magnétiques et amagnétiques.

  12. Hierarchical organization in aggregates of protein molecules

    DEFF Research Database (Denmark)

    Bohr, Henrik; Kyhle, Anders; Sørensen, Alexis Hammer

    1997-01-01

    of the solution and the density of protein are varied shows the existence of specific growth processes resulting in different branch-like structures. The resulting structures are strongly influenced by the shape of each protein molecule. Lysozyme and ribonuclease are found to form spherical structures...

  13. Writing with molecules on molecular printboards

    NARCIS (Netherlands)

    Crespo biel, O.; Ravoo, B.J.; Huskens, Jurriaan; Reinhoudt, David

    2006-01-01

    Nanotechnology aspires to create functional materials with characteristic dimensions of the order 1–100 nm. One requirement to make nanotechnology work is to precisely position molecules and nanoparticles on surfaces, so that they may be addressed and manipulated for bottom-up construction of

  14. Coupled Cluster Theory for Large Molecules

    DEFF Research Database (Denmark)

    Baudin, Pablo

    This thesis describes the development of local approximations to coupled cluster (CC) theory for large molecules. Two different methods are presented, the divide–expand–consolidate scheme (DEC), for the calculation of ground state energies, and a local framework denoted LoFEx, for the calculation...

  15. Photoelectron spectroscopy of heavy atoms and molecules

    International Nuclear Information System (INIS)

    White, M.G.

    1979-07-01

    The importance of relativistic interactions in the photoionization of heavy atoms and molecules has been investigated by the technique of photoelectron spectroscopy. In particular, experiments are reported which illustrate the effects of the spin-orbit interaction in the neutral ground state, final ionic states and continuum states of the photoionization target

  16. Kidney injury molecule-1 in renal disease

    NARCIS (Netherlands)

    Waanders, Femke; van Timmeren, Mirjan M.; Stegeman, Coen A.; Bakker, Stephan J. L.; van Goor, Harry

    Kidney injury molecule-1 (KIM-1) is a marker for renal proximal tubular damage, the hallmark of virtually all proteinuric, toxic and ischaemic kidney diseases. KIM-1 has gained increasing interest because of its possible pathophysiological role in modulating tubular damage and repair. In this

  17. Organic- and molecule-based magnets

    Indian Academy of Sciences (India)

    The discovery of organic- and molecule-based magnets has led to design and synthesis of several families with magnetic ordering temperatures as high as ∼ 125° C. Examples of soft and hard magnets with coercivities as high as 27 kOe have also been reported. Examples from our laboratory of organic-based magnets ...

  18. Controlled transport through a single molecule

    NARCIS (Netherlands)

    Kumar, Avijit; Heimbuch, Rene; Poelsema, Bene; Zandvliet, Henricus J.W.

    2012-01-01

    We demonstrate how an electrode–molecule–electrode junction can be controllably opened and closed by careful tuning of the contacts' interspace and voltage. The molecule, an octanethiol, flips to bridge a ~1 nm interspace between substrate and scanning tunnelling microscope tip when an electric

  19. The formation of molecules in protostellar winds

    International Nuclear Information System (INIS)

    Glassgold, A.E.; Mamon, G.A.; Huggins, P.J.

    1991-01-01

    The production and destruction processes for molecules in very fast protostellar winds are analyzed and modeled with a one-dimensional chemical kinetics code. Radial density and temperature distributions suggested by protostellar theory are explored as are a range of mass-loss rates. The efficiency of in situ formation of heavy molecules is found to be high if the wind temperature falls sufficiently rapidly, as indicated by theory. The degree of molecular conversion is a strong function of the mass-loss rate and of density gradients associated with the acceleration and collimation of the wind. Even in cases where essentially all of the heavy atoms are processed into molecules, a significant fraction of atomic hydrogen remains so that hghly molecular, protostellar winds are able to emit the 21-cm line. Although CO has a substantial abundance in most models relevant to very young protostars, high abundances of other molecules such as SiO and H2O signify more complete association characteristic of winds containing regions of very high density. Although the models apply only to regions close to the protostar, they are in qualitative accord with recent observations at much larger distances of both atomic and molecular emission from extremely high-velocity flow. 57 refs

  20. Cluster ions and van der Waals molecules

    CERN Document Server

    Smirnov, Boris M

    1992-01-01

    This review discusses current ideas in the physics and chemistry of cluster ions and Van der Waals molecules as well as presenting numerical data on their parameters and the processes involving them. It is also a detailed reference on basic data relating to many species.

  1. Optical Spectroscopy Of Charged Quantum Dot Molecules

    Science.gov (United States)

    Scheibner, M.; Bracker, A. S.; Stinaff, E. A.; Doty, M. F.; Gammon, D.; Ponomarev, I. V.; Reinecke, T. L.; Korenev, V. L.

    2007-04-01

    Coupling between two closely spaced quantum dots is observed by means of photoluminescence spectroscopy. Hole coupling is realized by rational crystal growth and heterostructure design. We identify molecular resonances of different excitonic charge states, including the important case of a doubly charged quantum dot molecule.

  2. Comprehensive Map of Molecules Implicated in Obesity.

    Directory of Open Access Journals (Sweden)

    Jaisri Jagannadham

    Full Text Available Obesity is a global epidemic affecting over 1.5 billion people and is one of the risk factors for several diseases such as type 2 diabetes mellitus and hypertension. We have constructed a comprehensive map of the molecules reported to be implicated in obesity. A deep curation strategy was complemented by a novel semi-automated text mining system in order to screen 1,000 full-length research articles and over 90,000 abstracts that are relevant to obesity. We obtain a scale free network of 804 nodes and 971 edges, composed of 510 proteins, 115 genes, 62 complexes, 23 RNA molecules, 83 simple molecules, 3 phenotype and 3 drugs in "bow-tie" architecture. We classify this network into 5 modules and identify new links between the recently discovered fat mass and obesity associated FTO gene with well studied examples such as insulin and leptin. We further built an automated docking pipeline to dock orlistat as well as other drugs against the 24,000 proteins in the human structural proteome to explain the therapeutics and side effects at a network level. Based upon our experiments, we propose that therapeutic effect comes through the binding of one drug with several molecules in target network, and the binding propensity is both statistically significant and different in comparison with any other part of human structural proteome.

  3. Photoinduced electron transfer in some photosensitive molecules ...

    Indian Academy of Sciences (India)

    Unknown

    redox reactions of substrates like biological molecules,11,12 dyes,13,14 alcohols15,16 etc. Colloidal ... state which is characterised by a phenomenon of dual fluorescence. In the present ... The dried solid was transferred to quartz cell under vacuum ... Recently Grätzel et al34 have developed the dye-sensitized meso-.

  4. Laser Control of Atoms and Molecules

    CERN Document Server

    Letkhov, V S

    2007-01-01

    This text treats laser light as a universal tool to control matter at the atomic and molecular level, one of the most exciting applications of lasers. Lasers can heat matter, cool atoms to ultra-low temperatures where they show quantum collective behaviour, and can act selectively on specific atoms and molecules for their detection and separation.

  5. On circumstellar molecules in the Pleiades.

    Science.gov (United States)

    Hobbs, L. M.

    1972-01-01

    Consideration of both old and new observations of the interstellar 4232-A line of CH(+) for the brightest members of the Pleiades. These observations suggest that the molecules are circumstellar in some sense, perhaps resembling in this respect the micron-sized grains inferred to be present in this region.

  6. Chemical reactivities of some interstellar molecules

    Energy Technology Data Exchange (ETDEWEB)

    Chadha, M S

    1980-01-01

    Work in the area of chemical evolution during the last 25 years has revealed the formation of a large number of biologically important molecules produced from simple starting materials under relatively simple experimental conditions. Much of this work has resulted from studies under atmospheres simulating that of the primitive earth or other planets. During the last decade, progress has also been made in the identification of chemical constituents of interstellar medium. A number of these molecules are the same as those identified in laboratory experiments. Even though the conditions of the laboratory experiments are vastly different from those of the cool, low-density interstellar medium, some of the similarities in composition are too obvious to go unnoticed. The present paper highlights some of the similarities in the composition of prebiotic molecules and those discovered in the interstellar medium. Also the chemical reactions which some of the common molecules e.g., NH3, HCN, H2CO, HC(triple bond)-C-CN etc. can undergo are surveyed.

  7. Single Molecule Conductance of Oligothiophene Derivatives

    Science.gov (United States)

    Dell, Emma J.

    This thesis studies the electronic properties of small organic molecules based on the thiophene motif. If we are to build next-generation devices, advanced materials must be designed which possess requisite electronic functionality. Molecules present attractive candidates for these ad- vanced materials since nanoscale devices are particularly sought after. However, selecting a molecule that is suited to a certain electronic function remains a challenge, and characterization of electronic behavior is therefore critical. Single molecule conductance measurements are a powerful tool to determine properties on the nanoscale and, as such, can be used to investigate novel building blocks that may fulfill the design requirements of next-generation devices. Combining these conductance results with strategic chemical synthesis allows for the development of new families of molecules that show attractive properties for future electronic devices. Since thiophene rings are the fruitflies of organic semiconductors on the bulk scale, they present an intriguing starting point for building functional materials on the nanoscale, and therefore form the structural basis of all molecules studied herein. First, the single-molecule conductance of a family of bithiophene derivatives was measured. A broad distribution in the single-molecule conductance of bithiophene was found compared with that of a biphenyl. This increased breadth in the conductance distribution was shown to be explained by the difference in 5-fold symmetry of thiophene rings as compared to the 6-fold symmetry of benzene rings. The reduced symmetry of thiophene rings results in a restriction on the torsion angle space available to these molecules when bound between two metal electrodes in a junction, causing each molecular junction to sample a different set of conformers in the conductance measurements. By contrast, the rotations of biphenyl are essentially unimpeded by junction binding, allowing each molecular junction

  8. Quantum interference experiments with complex organic molecules

    International Nuclear Information System (INIS)

    Eibenberger, S. I.

    2015-01-01

    Matter-wave interference with complex particles is a thriving field in experimental quantum physics. The quest for testing the quantum superposition principle with highly complex molecules has motivated the development of the Kapitza-Dirac-Talbot-Lau interferometer (KDTLI). This interferometer has enabled quantum interference with large organic molecules in an unprecedented mass regime. In this doctoral thesis I describe quantum superposition experiments which we were able to successfully realize with molecules of masses beyond 10 000 amu and consisting of more than 800 atoms. The typical de Broglie wavelengths of all particles in this thesis are in the order of 0.3-5 pm. This is significantly smaller than any molecular extension (nanometers) or the delocalization length in our interferometer (hundreds of nanometers). Many vibrational and rotational states are populated since the molecules are thermally highly excited (300-1000 K). And yet, high-contrast quantum interference patterns could be observed. The visibility and position of these matter-wave interference patterns is highly sensitive to external perturbations. This sensitivity has opened the path to extensive studies of the influence of internal molecular properties on the coherence of their associated matter waves. In addition, it enables a new approach to quantum-assisted metrology. Quantum interference imprints a high-contrast nano-structured density pattern onto the molecular beam which allows us to resolve tiny shifts and dephasing of the molecular beam. I describe how KDTL interferometry can be used to investigate a number of different molecular properties. We have studied vibrationally-induced conformational changes of floppy molecules and permanent electric dipole moments using matter-wave deflectometry in an external electric field. We have developed a new method for optical absorption spectroscopy which uses the recoil of the molecules upon absorption of individual photons. This allows us to

  9. Single Molecule Nanoelectrochemistry in Electrical Junctions.

    Science.gov (United States)

    Nichols, Richard J; Higgins, Simon J

    2016-11-15

    It is now possible to reliably measure single molecule conductance in a wide variety of environments including organic liquids, ultrahigh vacuum, water, ionic liquids, and electrolytes. The most commonly used methods deploy scanning probe microscopes, mechanically formed break junctions, or lithographically formed nanogap contacts. Molecules are generally captured between a pair of facing electrodes, and the junction current response is measured as a function of bias voltage. Gating electrodes can also be added so that the electrostatic potential at the molecular bridge can be independently controlled by this third noncontacting electrode. This can also be achieved in an electrolytic environment using a four-electrode bipotentiostatic configuration, which allows independent electrode potential control of the two contacting electrodes. This is commonly realized using an electrochemical STM and enables single molecule electrical characterization as a function of electrode potential and redox state of the molecular bridge. This has emerged as a powerful tool in modern interfacial electrochemistry and nanoelectrochemistry for studying charge transport across single molecules as a function of electrode potential and the electrolytic environments. Such measurements are possible in electrolytes ranging from aqueous buffers to nonaqueous ionic liquids. In this Account, we illustrate a number of examples of single molecule electrical measurements under electrode potential control use a scanning tunneling microscope (STM) and demonstrate how these can help in the understanding of charge transport in single molecule junctions. Examples showing charge transport following phase coherent tunneling to incoherent charge hopping across redox active molecular bridges are shown. In the case of bipyridinium (or viologen) molecular wires, it is shown how electrochemical reduction leads to an increase of the single molecule conductance, which is controlled by the liquid electrochemical

  10. Molecules for Fluorescence Detection of Specific Chemicals

    Science.gov (United States)

    Fedor, Steve

    2008-01-01

    A family of fluorescent dye molecules has been developed for use in on-off fluorescence detection of specific chemicals. By themselves, these molecules do not fluoresce. However, when exposed to certain chemical analytes in liquid or vapor forms, they do fluoresce (see figure). These compounds are amenable to fixation on or in a variety of substrates for use in fluorescence-based detection devices: they can be chemically modified to anchor them to porous or non-porous solid supports or can be incorporated into polymer films. Potential applications for these compounds include detection of chemical warfare agents, sensing of acidity or alkalinity, and fluorescent tagging of proteins in pharmaceutical research and development. These molecules could also be exploited for use as two-photon materials for photodynamic therapy in the treatment of certain cancers and other diseases. A molecule in this family consists of a fluorescent core (such as an anthracene or pyrene) attached to two end groups that, when the dye is excited by absorption of light, transfer an electron to the core, thereby quenching the fluorescence. The end groups can be engineered so that they react chemically with certain analytes. Upon reaction, electrons on the end groups are no longer available for transfer to the core and, consequently, the fluorescence from the core is no longer quenched. The chemoselectivity of these molecules can be changed by changing the end groups. For example, aniline end groups afford a capability for sensing acids or acid halides (including those contained in chemical warfare agents). Pyridine or bipyridyl end groups would enable sensing of metal ions. Other chemicals that can be selectively detected through suitable choice of end groups include glucose and proteins. Moreover, the fluorescent cores can be changed to alter light-absorption and -emission characteristics: anthracene cores fluoresce at wavelengths around 500 nm, whereas perylene cores absorb and emit at

  11. Molecular electronics: the single molecule switch and transistor

    NARCIS (Netherlands)

    Sotthewes, Kai; Geskin, Victor; Heimbuch, Rene; Kumar, Avijit; Zandvliet, Henricus J.W.

    2014-01-01

    In order to design and realize single-molecule devices it is essential to have a good understanding of the properties of an individual molecule. For electronic applications, the most important property of a molecule is its conductance. Here we show how a single octanethiol molecule can be connected

  12. Protection of a PWR nuclear power stations against corrosion using hydrogen molecules to capture oxygen molecules

    International Nuclear Information System (INIS)

    Nahili, M.

    2004-01-01

    A protection method for the primary loops metals of nuclear power plants from corrosion was investigated. Hydrogen molecules were added to the primary circuit to eliminate oxygen molecules produced by radiolysis of coolant at the reactor core. The hydrogen molecules were produced by electrolyses of water and then added when the coolant water was passing through the primary coolant circuit. Thermodynamical process and the protection methods from corrosion were discussed, the discussion emphasized on the removal of oxygen molecules as one of the protection methods, and compared with other methods. The amount of hydrogen molecules needed for complete removal of oxygen was estimated in two cases: in the case without passing the water through the oxygen removal system, and in the case of passing water through the system. A pressurized water reactor VVER was chosen to be investigated in this study. The amount of hydrogen molecules was estimated so as to eliminate completely the oxygen molecules from coolant water. The estimated value was found to be less than the permissible range for coolant water for such type of reactors. A simulation study for interaction mechanism between hydrogen and oxygen molecules as water flowing in a tube similar to that of coolant water was performed with different water flow velocities. The interaction between the molecules of hydrogen and oxygen was described. The gas diffusion at the surface of the tube was found to play a major role in the interaction. A mathematical model was found to give full description of the change of oxygen concentration through the tube, as well as, to calculate the length of the tube where the concentration of oxygen reduced to few order of magnitude. (Author)

  13. Preface: Special Topic on Single-Molecule Biophysics.

    Science.gov (United States)

    Makarov, Dmitrii E; Schuler, Benjamin

    2018-03-28

    Single-molecule measurements are now almost routinely used to study biological systems and processes. The scope of this special topic emphasizes the physics side of single-molecule observations, with the goal of highlighting new developments in physical techniques as well as conceptual insights that single-molecule measurements bring to biophysics. This issue also comprises recent advances in theoretical physical models of single-molecule phenomena, interpretation of single-molecule signals, and fundamental areas of statistical mechanics that are related to single-molecule observations. A particular goal is to illustrate the increasing synergy between theory, simulation, and experiment in single-molecule biophysics.

  14. Neutral molecules in tokamak edge plasma - role of vibrationally excited hydrogen molecules

    International Nuclear Information System (INIS)

    Cadez, I.; Cercek, M.; Pelicon, P.; Razpet, A.

    2003-01-01

    The role of neutral molecules in edge plasma is discussed with special emphasis on the vibrationally excited hydrogen. Neutral molecules are formed mostly by surface processes on the walls and then released to the edge plasma where they take part in volumetric reactions with other particles. Typically these molecules are formed in excited states and data are needed for their reactions on the wall and in the volume. Processes in edge plasma determine particle and energy flux what is especially critical issue in tokamak divertor region. Various cross sections and reaction rates are needed for modelling edge plasma and its interaction with walls. (author)

  15. Synthesis of single-molecule nanocars.

    Science.gov (United States)

    Vives, Guillaume; Tour, James M

    2009-03-17

    The drive to miniaturize devices has led to a variety of molecular machines inspired by macroscopic counterparts such as molecular motors, switches, shuttles, turnstiles, barrows, elevators, and nanovehicles. Such nanomachines are designed for controlled mechanical motion and the transport of nanocargo. As researchers miniaturize devices, they can consider two complementary approaches: (1) the "top-down" approach, which reduces the size of macroscopic objects to reach an equivalent microscopic entity using photolithography and related techniques and (2) the "bottom-up" approach, which builds functional microscopic or nanoscopic entities from molecular building blocks. The top-down approach, extensively used by the semiconductor industry, is nearing its scaling limits. On the other hand, the bottom-up approach takes advantage of the self-assembly of smaller molecules into larger networks by exploiting typically weak molecular interactions. But self-assembly alone will not permit complex assembly. Using nanomachines, we hope to eventually consider complex, enzyme-like directed assembly. With that ultimate goal, we are currently exploring the control of nanomachines that would provide a basis for the future bottom-up construction of complex systems. This Account describes the synthesis of a class of molecular machines that resemble macroscopic vehicles. We designed these so-called nanocars for study at the single-molecule level by scanning probe microscopy (SPM). The vehicles have a chassis connected to wheel-terminated axles and convert energy inputs such as heat, electric fields, or light into controlled motion on a surface, ultimately leading to transport of nanocargo. At first, we used C(60) fullerenes as wheels, which allowed the demonstration of a directional rolling mechanism of a nanocar on a gold surface by STM. However, because of the low solubility of the fullerene nanocars and the incompatibility of fullerenes with photochemical processes, we developed new

  16. Environmental effects on molecules immersed in liquids

    International Nuclear Information System (INIS)

    Sese, L.M.

    1990-01-01

    A methodology to study environmental effects is thoroughly discussed. It combines molecular quantum mechanics and classical statistical mechanics of molecular fluids. Pair distribution functions collecting statistical information appear quite naturally in the quantum equations describing a single molecule. As well as allowing the computation of any individual molecular property in a liquid phase, this approach satisfies a number of theoretical requirements (dependence on density and temperature, validity in the thermodynamic limit). In a sense, it can be regarded as a useful alternative to the well-known Monte Carlo averaging processes for calculating molecular properties. Numerical applications studying liquid carbon disulphide and liquid carbon tetrachloride at several state points are given. Results cover typical RHF information (CNDO/2) on molecules, and show the sensitivity of the presented methodology to structural changes in liquids. (orig.)

  17. Organization of central synapses by adhesion molecules.

    Science.gov (United States)

    Tallafuss, Alexandra; Constable, John R L; Washbourne, Philip

    2010-07-01

    Synapses are the primary means for transmitting information from one neuron to the next. They are formed during the development of the nervous system, and the formation of appropriate synapses is crucial for the establishment of neuronal circuits that underlie behavior and cognition. Understanding how synapses form and are maintained will allow us to address developmental disorders such as autism, mental retardation and possibly also psychological disorders. A number of biochemical and proteomic studies have revealed a diverse and vast assortment of molecules that are present at the synapse. It is now important to untangle this large array of proteins and determine how it assembles into a functioning unit. Here we focus on recent reports describing how synaptic cell adhesion molecules interact with and organize the presynaptic and postsynaptic specializations of both excitatory and inhibitory central synapses. © The Authors (2010). Journal Compilation © Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  18. Continuous centrifuge decelerator for polar molecules.

    Science.gov (United States)

    Chervenkov, S; Wu, X; Bayerl, J; Rohlfes, A; Gantner, T; Zeppenfeld, M; Rempe, G

    2014-01-10

    Producing large samples of slow molecules from thermal-velocity ensembles is a formidable challenge. Here we employ a centrifugal force to produce a continuous molecular beam with a high flux at near-zero velocities. We demonstrate deceleration of three electrically guided molecular species, CH3F, CF3H, and CF3CCH, with input velocities of up to 200  m s(-1) to obtain beams with velocities below 15  m s(-1) and intensities of several 10(9)  mm(-2) s(-1). The centrifuge decelerator is easy to operate and can, in principle, slow down any guidable particle. It has the potential to become a standard technique for continuous deceleration of molecules.

  19. Computational mass spectrometry for small molecules

    Science.gov (United States)

    2013-01-01

    The identification of small molecules from mass spectrometry (MS) data remains a major challenge in the interpretation of MS data. This review covers the computational aspects of identifying small molecules, from the identification of a compound searching a reference spectral library, to the structural elucidation of unknowns. In detail, we describe the basic principles and pitfalls of searching mass spectral reference libraries. Determining the molecular formula of the compound can serve as a basis for subsequent structural elucidation; consequently, we cover different methods for molecular formula identification, focussing on isotope pattern analysis. We then discuss automated methods to deal with mass spectra of compounds that are not present in spectral libraries, and provide an insight into de novo analysis of fragmentation spectra using fragmentation trees. In addition, this review shortly covers the reconstruction of metabolic networks using MS data. Finally, we list available software for different steps of the analysis pipeline. PMID:23453222

  20. Handbook of Single-Molecule Biophysics

    CERN Document Server

    Hinterdorfer, Peter

    2009-01-01

    The last decade has seen the development of a number of novel biophysical methods that allow the manipulation and study of individual biomolecules. The ability to monitor biological processes at this fundamental level of sensitivity has given rise to an improved understanding of the underlying molecular mechanisms. Through the removal of ensemble averaging, distributions and fluctuations of molecular properties can be characterized, transient intermediates identified, and catalytic mechanisms elucidated. By applying forces on biomolecules while monitoring their activity, important information can be obtained on how proteins couple function to structure. The Handbook of Single-Molecule Biophysics provides an introduction to these techniques and presents an extensive discussion of the new biological insights obtained from them. Coverage includes: Experimental techniques to monitor and manipulate individual biomolecules The use of single-molecule techniques in super-resolution and functional imaging Single-molec...

  1. Future Directions for Transuranic Single Molecule Magnets

    Directory of Open Access Journals (Sweden)

    Nicola Magnani

    2018-02-01

    Full Text Available Single Molecule Magnets (SMMs based on transition metals and rare earths have been the object of considerable attention for the past 25 years. These systems exhibit slow relaxation of the magnetization, arising from a sizeable anisotropy barrier, and magnetic hysteresis of purely molecular origin below a given blocking temperature. Despite initial predictions that SMMs based on 5f-block elements could outperform most others, the results obtained so far have not met expectations. Exploiting the versatile chemistry of actinides and their favorable intrinsic magnetic properties proved, indeed, to be more difficult than assumed. However, the large majority of studies reported so far have been dedicated to uranium molecules, thus leaving the largest part of the 5f-block practically unexplored. Here, we present a short review of the progress achieved up to now and discuss some options for a possible way forward.

  2. Design of small molecule epigenetic modulators.

    Science.gov (United States)

    Pachaiyappan, Boobalan; Woster, Patrick M

    2014-01-01

    The field of epigenetics has expanded rapidly to reveal multiple new targets for drug discovery. The functional elements of the epigenomic machinery can be categorized as writers, erasers and readers, and together these elements control cellular gene expression and homeostasis. It is increasingly clear that aberrations in the epigenome can underly a variety of diseases, and thus discovery of small molecules that modulate the epigenome in a specific manner is a viable approach to the discovery of new therapeutic agents. In this Digest, the components of epigenetic control of gene expression will be briefly summarized, and efforts to identify small molecules that modulate epigenetic processes will be described. Copyright © 2013 The Authors. Published by Elsevier Ltd.. All rights reserved.

  3. The X(3872) boson: Molecule or charmonium

    International Nuclear Information System (INIS)

    Suzuki, Mahiko

    2005-01-01

    It has been argued that the mystery boson X(3872) is a molecular state consisting of primarily D 0 (bar D)* 0 + (bar D) 0 D* 0 . In contrast, apparent puzzles and potential difficulties have been pointed out for the charmonium assignment of X(3872). They examine several aspects of these alternatives by semi-quantitative methods since quantitatively accurate results are often hard to reach on them. they point out that some of the observed properties of X(3872), in particular, the binding and the production rates are incompatible with the molecule interpretation. Despite puzzles and obstacles, X(3872) may fit more likely to the excited 3 P 1 charmonium than to the molecule after the mixing of c(bar c) with D(bar D)* + (bar D)D* is taken into account

  4. Spectroscopy of fractional Josephson vortex molecules

    Energy Technology Data Exchange (ETDEWEB)

    Goldobin, Edward; Gaber, Tobias; Buckenmaier, Kai; Kienzle, Uta; Sickinger, Hanna; Koelle, Dieter; Kleiner, Reinhold [Physikalisches Institut - Experimentalphysik II, Center for Collective Quantum Phenomena, Universitaet Tuebingen, Auf der Morgenstelle 14, D-72076 Tuebingen (Germany)

    2010-07-01

    Using tiny current injectors we create {kappa} discontinuities of the Josephson phase in a long Josephson junction. The junction reacts at the discontinuities by creating fractional Josephson vortices of size {lambda}{sub J} pinned at them. Such vortices carry the flux {phi}, which is a fraction of the magnetic flux quantum {phi}{sub 0}{approx}2.07 x 10{sup -15} Wb. Being pinned, a fractional vortex has an eigenfrequency (localized mode), which depends on {kappa} and applied bias current, and which lays within the plasma gap. If one considers a molecule consisting of several coupled fractional vortices, the eigenfrequency will split into several modes. We report on spectroscopy of a fractional vortex molecule performed in the thermal regime.

  5. Energy redistribution in diatomic molecules on surfaces

    International Nuclear Information System (INIS)

    Asscher, M.; Somorjai, G.A.

    1984-04-01

    Translational and internal degrees of freedom of a scattered beam of NO molecules from a Pt(111) single crystal surface were measured as a function of scattering angle and crystal temperature in the range 450 to 1250K. None of the three degrees of freedom were found to fully accommodate to the crystal temperature, the translational degree being the most accommodated and the rotational degree of freedom the least. A precursor state model is suggested to account for the incomplete accommodation of translational and vibrational degrees of freedom as a function of crystal temperature and incident beam energy. The vibrational accommodation is further discussed in terms of a competition between desorption and vibrational excitation processes, thus providing valuable information on the interaction between vibrationally excited molecules and surfaces. Energy transfer into rotational degrees of freedom is qualitatively discussed

  6. Field-free orientation of molecules

    DEFF Research Database (Denmark)

    Machholm, Mette; Henriksen, Niels Engholm

    2001-01-01

    The excitation of angular motion, in particular, the creation of a wave packet in the angular degrees of freedom via short-pulse, off-resonant excitation with respect to rotational transitions, was examined. The key result was that field-free time-dependent orientation for a molecule like LiH can...... be generated after the turn-off of a state-of-the-art electromagnetic half-cycle pulse.......The excitation of angular motion, in particular, the creation of a wave packet in the angular degrees of freedom via short-pulse, off-resonant excitation with respect to rotational transitions, was examined. The key result was that field-free time-dependent orientation for a molecule like LiH can...

  7. Formation and decomposition of astatine molecules

    International Nuclear Information System (INIS)

    Takahashi, Naruto; Ishikuro, Mituhiro; Baba Hiroshi

    1989-01-01

    A method determining the boiling points of elementary astatine and astatine iodide has been developed (K. Otozai and N. Takahashi, Radio. Chim. Acta 31, (1982) 201). Further, it was concluded from the simple rule among the boiling point of elementary halogens and interhalogen compounds that elementary astatine might exist in diatomic molecules as the other halogens. In the present work the reaction mechanisms of elementary astatine with radioactive iodine and organic solvents were studied by means of radiogaschromatography in order to obtain further experimental evidences for diatomic astaine molecules. The following conclusions were obtained by the analysis of reaction kinetics. Two astatine atoms are lost from the elementary astatine fraction per each radioactive decay of astatine. The astatine radical or hot atom liberated by the decay of the complementary astatine atom immediately reacts with iodine or organic solvents. Thus formed astatine compounds decompose in turn due to the decay of astatine

  8. Theory of Charged Quantum Dot Molecules

    Science.gov (United States)

    Ponomarev, I. V.; Scheibner, M.; Stinaff, E. A.; Bracker, A. S.; Doty, M. F.; Ware, M. E.; Gammon, D.; Reinecke, T. L.; Korenev, V. L.

    2006-03-01

    Recent optical spectroscopy of excitonic molecules in coupled quantum dots (CQDs) tuned by electric field reveal a richer diversity in spectral line patterns than in their single quantum dot counterparts. We developed a theoretical model that allows us to classify energies and intensities of various PL transitions. In this approach the electric field induced resonance tunneling of the electron and hole states occurs at different biases due to the inherent asymmetry of CQDs. The truncated many-body basis configurations for each molecule are constructed from antisymmetrized products of single-particle states, where the electron occupies only one ground state level in single QD and the hole can occupy two lowest levels of CQD system. The Coulomb interaction between particles is treated with perturbation theory. As a result the observed PL spectral lines can be described with a small number of parameters. The theoretical predictions account well for recent experiments.

  9. Structural characterization of some substituted azolidine molecules

    International Nuclear Information System (INIS)

    Andreocci, M.V.; Bossa, M.; Furlani, C.; Mattogno, G.; Zanoni, R.; Consiglio Nazionale delle Ricerche, Rome; Devillanova, F.A.; Verani, G.

    1981-01-01

    The electronic structure of a series of organic molecules of general formula RN - (CH 2 ) 2 - X - C = Y, which are also of interest in inorganic chemistry because of their properties as ligands towards metals, have been investigated by X-ray photoelectron spectroscopy. The results suggest a general picture of atomic charge distribution within the investigated molecules, and allow an assessment of the effect of the different substituent groups X, Y, R (X = NR', O, S, CH 2 ; Y = O, S, Se; R, R' = H, alkyl) on the electronic structure of the ligands. Satisfactory correlation is found between experimental binding energies and computed CNDO/2 atomic charges, after correction for intramolecular Madelung potentials. (orig.)

  10. Photochemical dynamics of surface oriented molecules

    International Nuclear Information System (INIS)

    Ho, W.

    1992-01-01

    The period 8/01/91-7/31/92 is the first year of a new project titled ''Photochemical Dynamics of Surface Oriented Molecules'', initiated with DOE Support. The main objective of this project is to understand the dynamics of elementary chemical reactions by studying photochemical dynamics of surface-oriented molecules. In addition, the mechanisms of photon-surface interactions need to be elucidated. The strategy is to carry out experiments to measure the translational energy distribution, as a function of the angle from the surface normal, of the photoproducts by time-of-flight (TOF) technique by varying the photon wavelength, intensity, polarization, and pulse duration. By choosing adsorbates with different bonding configuration, the effects of adsorbate orientation on surface photochemical dynamics can be studied

  11. Automated imaging system for single molecules

    Science.gov (United States)

    Schwartz, David Charles; Runnheim, Rodney; Forrest, Daniel

    2012-09-18

    There is provided a high throughput automated single molecule image collection and processing system that requires minimal initial user input. The unique features embodied in the present disclosure allow automated collection and initial processing of optical images of single molecules and their assemblies. Correct focus may be automatically maintained while images are collected. Uneven illumination in fluorescence microscopy is accounted for, and an overall robust imaging operation is provided yielding individual images prepared for further processing in external systems. Embodiments described herein are useful in studies of any macromolecules such as DNA, RNA, peptides and proteins. The automated image collection and processing system and method of same may be implemented and deployed over a computer network, and may be ergonomically optimized to facilitate user interaction.

  12. Intercellular adhesion molecules (ICAMs) and spermatogenesis

    Science.gov (United States)

    Xiao, Xiang; Mruk, Dolores D.; Cheng, C. Yan

    2013-01-01

    BACKGROUND During the seminiferous epithelial cycle, restructuring takes places at the Sertoli–Sertoli and Sertoli–germ cell interface to accommodate spermatogonia/spermatogonial stem cell renewal via mitosis, cell cycle progression and meiosis, spermiogenesis and spermiation since developing germ cells, in particular spermatids, move ‘up and down’ the seminiferous epithelium. Furthermore, preleptotene spermatocytes differentiated from type B spermatogonia residing at the basal compartment must traverse the blood–testis barrier (BTB) to enter the adluminal compartment to prepare for meiosis at Stage VIII of the epithelial cycle, a process also accompanied by the release of sperm at spermiation. These cellular events that take place at the opposite ends of the epithelium are co-ordinated by a functional axis designated the apical ectoplasmic specialization (ES)—BTB—basement membrane. However, the regulatory molecules that co-ordinate cellular events in this axis are not known. METHODS Literature was searched at http://www.pubmed.org and http://scholar.google.com to identify published findings regarding intercellular adhesion molecules (ICAMs) and the regulation of this axis. RESULTS Members of the ICAM family, namely ICAM-1 and ICAM-2, and the biologically active soluble ICAM-1 (sICAM-1) are the likely regulatory molecules that co-ordinate these events. sICAM-1 and ICAM-1 have antagonistic effects on the Sertoli cell tight junction-permeability barrier, involved in Sertoli cell BTB restructuring, whereas ICAM-2 is restricted to the apical ES, regulating spermatid adhesion during the epithelial cycle. Studies in other epithelia/endothelia on the role of the ICAM family in regulating cell movement are discussed and this information has been evaluated and integrated into studies of these proteins in the testis to create a hypothetical model, depicting how ICAMs regulate junction restructuring events during spermatogenesis. CONCLUSIONS ICAMs are crucial

  13. Novel polymerizable bent-shaped monomeric molecules

    Czech Academy of Sciences Publication Activity Database

    Kozmik, V.; Kovářová, A.; Kuchař, M.; Svoboda, Jiří; Novotná, Vladimíra; Glogarová, Milada; Kroupa, Jan

    2006-01-01

    Roč. 33, č. 1 (2006), s. 41-56 ISSN 0267-8292 R&D Projects: GA ČR(CZ) GA202/05/0431; GA MŠk(CZ) OC D14.50 Institutional research plan: CEZ:AV0Z10100520 Keywords : mesogens * polymerizable * bent-shaped molecules * liquid crystals * ferroelectricity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.417, year: 2006

  14. Single-Molecule Interfacial Electron Transfer

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Wilson [Univ. of California, Irvine, CA (United States)

    2018-02-03

    Interfacial electron transfer (ET) plays an important role in many chemical and biological processes. Specifically, interfacial ET in TiO2-based systems is important to solar energy technology, catalysis, and environmental remediation technology. However, the microscopic mechanism of interfacial ET is not well understood with regard to atomic surface structure, molecular structure, bonding, orientation, and motion. In this project, we used two complementary methodologies; single-molecule fluorescence spectroscopy, and scanning-tunneling microscopy and spectroscopy (STM and STS) to address this scientific need. The goal of this project was to integrate these techniques and measure the molecular dependence of ET between adsorbed molecules and TiO2 semiconductor surfaces and the ET induced reactions such as the splitting of water. The scanning probe techniques, STM and STS, are capable of providing the highest spatial resolution but not easily time-resolved data. Single-molecule fluorescence spectroscopy is capable of good time resolution but requires further development to match the spatial resolution of the STM. The integrated approach involving Peter Lu at Bowling Green State University (BGSU) and Wilson Ho at the University of California, Irvine (UC Irvine) produced methods for time and spatially resolved chemical imaging of interfacial electron transfer dynamics and photocatalytic reactions. An integral aspect of the joint research was a significant exchange of graduate students to work at the two institutions. This project bridged complementary approaches to investigate a set of common problems by working with the same molecules on a variety of solid surfaces, but using appropriate techniques to probe under ambient (BGSU) and ultrahigh vacuum (UCI) conditions. The molecular level understanding of the fundamental interfacial electron transfer processes obtained in this joint project will be important for developing efficient light harvesting

  15. Isatin, a versatile molecule: studies in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Barbara, E-mail: barbara.iq@gmail.com [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil)

    2013-05-15

    Isatin is a small, versatile and widely applicable pharmacological molecule. These characteristics make isatin and its derivatives attractive to many research groups as resources for chemical and pharmacological studies. Although it has a relatively simple structure, isatin is a useful chemical scaffold for a variety of chemical transformations. This article discusses several studies performed by Brazilian groups, including investigations of its structural changes, biological assay designs and new methods for the synthesis of isatin. (author)

  16. Electron correlation in molecules and condensed phases

    CERN Document Server

    March, N H

    1996-01-01

    This reference describes the latest research on correlation effects in the multicenter problems of atoms, molecules, and solids The author utilizes first- and second-order matrices, including the important observable electron density rho(r), and the Green function for discussing quantum computer simulations With its focus on concepts and theories, this volume will benefit experimental physicists, materials scientists, and physical and inorganic chemists as well as graduate students

  17. Hidden charm molecules in a finite volume

    International Nuclear Information System (INIS)

    Albaladejo, M.; Hidalgo-Duque, C.; Nieves, J.; Oset, E.

    2014-01-01

    In the present paper we address the interaction of charmed mesons in hidden charm channels in a finite box. We use the interaction from a recent model based on heavy quark spin symmetry that predicts molecules of hidden charm in the infinite volume. The energy levels in the box are generated within this model, and several methods for the analysis of these levels ("inverse problem") are investigated. (author)

  18. Circular Intensity Differential Scattering of chiral molecules

    Energy Technology Data Exchange (ETDEWEB)

    Bustamante, C.J.

    1980-12-01

    In this thesis a theory of the Circular Intensity Differential Scattering (CIDS) of chiral molecules as modelled by a helix oriented with respect to the direction of incidence of light is presented. It is shown that a necessary condition for the existence of CIDS is the presence of an asymmetric polarizability in the scatterer. The polarizability of the scatterer is assumed generally complex, so that both refractive and absorptive phenomena are taken into account.

  19. Pseudopotential theory of atoms and molecules

    International Nuclear Information System (INIS)

    Szasz, L.

    1985-01-01

    This book reviews the pseudopotential theory of atoms and molecules. It refers to the quantum mechanical technique in which the Pauli exclusion principle is replaced by operators and potential functions, jointly called pseudopotentials. The book describes the development of the theory up to the state-of-the-art techniques. It discusses exact pseudopotentials for one-valence electron systems, density-dependent pseudopotentials for one-valence electron systems, and model pseudopotentials for one-valence electron systems

  20. Sensing single electrons with single molecules

    International Nuclear Information System (INIS)

    Plakhotnik, Taras

    2007-01-01

    We propose a new methodology for probing transport of just one electron, a process of great importance both in nature and in artificial devices. Our idea for locating a single electron is analogues to the conventional GPS where signals from several satellites are used to locate a macro object. Using fluorescent molecules as tiny sensors, it is possible to determine 3D displacement vector of an electron

  1. Single molecule SERS: Perspectives of analytical applications

    Czech Academy of Sciences Publication Activity Database

    Vlčková, B.; Pavel, I.; Sládková, M.; Šišková, K.; Šlouf, Miroslav

    834-836, - (2007), s. 42-47 ISSN 0022-2860. [European Congress on Molecular Spectroscopy /28./. Istanbul, 03.09.2006-08.09.2006] R&D Projects: GA ČR GA203/04/0688 Institutional research plan: CEZ:AV0Z40500505 Keywords : surface-enhanced Raman scattering (SERS) * surface-enhanced resonance Raman (SERRS) * single molecule SERS Subject RIV: CD - Macromolecular Chemistry Impact factor: 1.486, year: 2007

  2. Small Talk: Children's Everyday `Molecule' Ideas

    Science.gov (United States)

    Jakab, Cheryl

    2013-08-01

    This paper reports on 6-11-year-old children's `sayings and doings' (Harré 2002) as they explore molecule artefacts in dialectical-interactive teaching interviews (Fleer, Cultural Studies of Science Education 3:781-786, 2008; Hedegaard et al. 2008). This sociocultural study was designed to explore children's everyday awareness of and meaning-making with cultural molecular artefacts. Our everyday world is populated with an ever increasing range of molecular or nanoworld words, symbols, images, and games. What do children today say about these artefacts that are used to represent molecular world entities? What are the material and social resources that can influence a child's everyday and developing scientific ideas about `molecules'? How do children interact with these cognitive tools when given expert assistance? What meaning-making is afforded when children are socially and materially assisted in using molecular tools in early chemical and nanoworld thinking? Tool-dependent discursive studies show that provision of cultural artefacts can assist and direct developmental thinking across many domains of science (Schoultz et al., Human Development 44:103-118, 2001; Siegal 2008). Young children's use of molecular artefacts as cognitive tools has not received much attention to date (Jakab 2009a, b). This study shows 6-11-year-old children expressing everyday ideas of molecular artefacts and raising their own questions about the artefacts. They are seen beginning to domesticate (Erneling 2010) the words, symbols, and images to their own purposes when given the opportunity to interact with such artefacts in supported activity. Discursive analysis supports the notion that using `molecules' as cultural tools can help young children to begin `putting on molecular spectacles' (Kind 2004). Playing with an interactive game (ICT) is shown to be particularly helpful in assisting children's early meaning-making with representations of molecules, atoms, and their chemical symbols.

  3. Advanced SPARQL querying in small molecule databases

    Czech Academy of Sciences Publication Activity Database

    Galgonek, Jakub; Hurt, T.; Michlíková, V.; Onderka, P.; Schwarz, J.; Vondrášek, Jiří

    2016-01-01

    Roč. 8, Jun 6 (2016), č. článku 31. ISSN 1758-2946 R&D Projects: GA MŠk(CZ) LM2015047 Institutional support: RVO:61388963 Keywords : Resource Description Framework * SPARQL query language * Database of small molecules Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.220, year: 2016 http://jcheminf.springeropen.com/articles/10.1186/s13321-016-0144-4

  4. Conducting single-molecule magnet materials.

    Science.gov (United States)

    Cosquer, Goulven; Shen, Yongbing; Almeida, Manuel; Yamashita, Masahiro

    2018-05-11

    Multifunctional molecular materials exhibiting electrical conductivity and single-molecule magnet (SMM) behaviour are particularly attractive for electronic devices and related applications owing to the interaction between electronic conduction and magnetization of unimolecular units. The preparation of such materials remains a challenge that has been pursued by a bi-component approach of combination of SMM cationic (or anionic) units with conducting networks made of partially oxidized (or reduced) donor (or acceptor) molecules. The present status of the research concerning the preparation of molecular materials exhibiting SMM behaviour and electrical conductivity is reviewed, describing the few molecular compounds where both SMM properties and electrical conductivity have been observed. The evolution of this research field through the years is discussed. The first reported compounds are semiconductors in spite being able to present relatively high electrical conductivity, and the SMM behaviour is observed at low temperatures where the electrical conductivity of the materials is similar to that of an insulator. During the recent years, a breakthrough has been achieved with the coexistence of high electrical conductivity and SMM behaviour in a molecular compound at the same temperature range, but so far without evidence of a synergy between these properties. The combination of high electrical conductivity with SMM behaviour requires not only SMM units but also the regular and as far as possible uniform packing of partially oxidized molecules, which are able to provide a conducting network.

  5. Coinhibitory molecules in cancer biology and therapy.

    Science.gov (United States)

    Mocellin, Simone; Benna, Clara; Pilati, Pierluigi

    2013-04-01

    The adaptive immune response is controlled by checkpoints represented by coinhibitory molecules, which are crucial for maintaining self-tolerance and minimizing collateral tissue damage under physiological conditions. A growing body of preclinical evidence supports the hypothesis that unleashing this immunological break might be therapeutically beneficial in the fight against cancer, as it would elicit an effective antitumor immune response. Remarkably, recent clinical trials have demonstrated that this novel strategy can be highly effective in the treatment of patients with cancer, as shown by the paradigmatic case of ipilimumab (a monoclonal antibody blocking the coinhibitory molecule cytotoxic T lymphocyte associated antigen-4 [CTLA4]) that is opening a new era in the therapeutic approach to a chemoresistant tumor such as cutaneous melanoma. In this review we summarize the biology of coinhibitory molecules, overview the experimental and clinical attempts to interfere with these immune checkpoints to treat cancer and critically discuss the challenges posed by such a promising antitumor modality. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Phase space structure of triatomic molecules

    International Nuclear Information System (INIS)

    Lu, Z.; Kellman, M.E.

    1997-01-01

    The bifurcation structure is investigated for a Hamiltonian for the three coupled nonlinear vibrations of a highly excited triatomic molecule. The starting point is a quantum Hamiltonian used to fit experimental spectra. This Hamiltonian includes 1:1 Darling endash Dennison resonance coupling between the stretches, and 2:1 Fermi resonance coupling between the stretches and bend. A classical Hamiltonian is obtained using the Heisenberg correspondence principle. Surfaces of section show a pronounced degree of chaos at high energies, with a mixture of chaotic and regular dynamics. The large-scale bifurcation structure is found semianalytically, without recourse to numerical solution of Hamilton close-quote s equations, by taking advantage of the fact that the spectroscopic Hamiltonian has a conserved polyad quantum number, corresponding to an approximate constant of the motion of the molecule. Bifurcation diagrams are analyzed for a number of molecules including H 2 O, D 2 O, NO 2 , ClO 2 , O 3 , and H 2 S. copyright 1997 American Institute of Physics

  7. Entangled photons from single atoms and molecules

    Science.gov (United States)

    Nordén, Bengt

    2018-05-01

    The first two-photon entanglement experiment performed 50 years ago by Kocher and Commins (KC) provided isolated pairs of entangled photons from an atomic three-state fluorescence cascade. In view of questioning of Bell's theorem, data from these experiments are re-analyzed and shown sufficiently precise to confirm quantum mechanical and dismiss semi-classical theory without need for Bell's inequalities. Polarization photon correlation anisotropy (A) is useful: A is near unity as predicted quantum mechanically and well above the semi-classic range, 0 ⩽ A ⩽ 1 / 2 . Although yet to be found, one may envisage a three-state molecule emitting entangled photon pairs, in analogy with the KC atomic system. Antibunching in fluorescence from single molecules in matrix and entangled photons from quantum dots promise it be possible. Molecules can have advantages to parametric down-conversion as the latter photon distribution is Poissonian and unsuitable for producing isolated pairs of entangled photons. Analytical molecular applications of entangled light are also envisaged.

  8. Small molecule-guided thermoresponsive supramolecular assemblies

    KAUST Repository

    Rancatore, Benjamin J.; Mauldin, Clayton E.; Frechet, Jean; Xu, Ting

    2012-01-01

    Small organic molecules with strong intermolecular interactions have a wide range of desirable optical and electronic properties and rich phase behaviors. Incorporating them into block copolymer (BCP)-based supramolecules opens new routes to generate functional responsive materials. Using oligothiophene- containing supramolecules, we present systematic studies of critical thermodynamic parameters and kinetic pathway that govern the coassemblies of BCP and strongly interacting small molecules. A number of potentially useful morphologies for optoelectronic materials, including a nanoscopic network of oligothiophene and nanoscopic crystalline lamellae, were obtained by varying the assembly pathway. Hierarchical coassemblies of oligothiophene and BCP, rather than macrophase separation, can be obtained. Crystallization of the oligothiophene not only induces chain stretching of the BCP block the oligothiophene is hydrogen bonded to but also changes the conformation of the other BCP coil block. This leads to an over 70% change in the BCP periodicity (e.g., from 31 to 53 nm) as the oligothiophene changes from a melt to a crystalline state, which provides access to a large BCP periodicity using fairly low molecular weight BCP. The present studies have demonstrated the experimental feasibility of generating thermoresponsive materials that convert heat into mechanical energy. Incorporating strongly interacting small molecules into BCP supramolecules effectively increases the BCP periodicity and may also open new opportunities to tailor their optical properties without the need for high molecular weight BCP. © 2012 American Chemical Society.

  9. Photoexcitation circular dichroism in chiral molecules

    Science.gov (United States)

    Beaulieu, S.; Comby, A.; Descamps, D.; Fabre, B.; Garcia, G. A.; Géneaux, R.; Harvey, A. G.; Légaré, F.; Mašín, Z.; Nahon, L.; Ordonez, A. F.; Petit, S.; Pons, B.; Mairesse, Y.; Smirnova, O.; Blanchet, V.

    2018-05-01

    Chiral effects appear in a wide variety of natural phenomena and are of fundamental importance in science, from particle physics to metamaterials. The standard technique of chiral discrimination—photoabsorption circular dichroism—relies on the magnetic properties of a chiral medium and yields an extremely weak chiral response. Here, we propose and demonstrate an orders of magnitude more sensitive type of circular dichroism in neutral molecules: photoexcitation circular dichroism. This technique does not rely on weak magnetic effects, but takes advantage of the coherent helical motion of bound electrons excited by ultrashort circularly polarized light. It results in an ultrafast chiral response and the efficient excitation of a macroscopic chiral density in an initially isotropic ensemble of randomly oriented chiral molecules. We probe this excitation using linearly polarized laser pulses, without the aid of further chiral interactions. Our time-resolved study of vibronic chiral dynamics opens a way to the efficient initiation, control and monitoring of chiral chemical change in neutral molecules at the level of electrons.

  10. Electron microscope autoradiography of isolated DNA molecules

    International Nuclear Information System (INIS)

    Delain, Etienne; Bouteille, Michel

    1980-01-01

    Autoradiographs of 3 H-thymidine-labelled DNA molecules were observed with an electron microscope. After ten months of exposure significant labelling was obtained with tritiated T7 DNA molecules which had a specific activity of 630,000 cpm/μg. Although isolated DNA molecules were not stretched out to such an extent that they could be rigorously compared to straight 'hot lines', the resolution was estimated and found to be similar to that obtained by autoradiography on thin plastic sections. The H.D. value was of the order of 1600A. From the known specific activity of the macromolecules, it was possible to compare the expected number of disintegrations from the samples to the number of grains obtained on the autoradiograms. This enabled us to calculate 1/ The absolute autoradiographic efficiency and 2/ The per cent ratio of thymidine residues labelled with tritium. These results throw some light on the resolution and sensitivity of electron microscope autoradiography of shadowed isolated macromolecules as compared to thin plastic sections

  11. Small molecule-guided thermoresponsive supramolecular assemblies

    KAUST Repository

    Rancatore, Benjamin J.

    2012-10-23

    Small organic molecules with strong intermolecular interactions have a wide range of desirable optical and electronic properties and rich phase behaviors. Incorporating them into block copolymer (BCP)-based supramolecules opens new routes to generate functional responsive materials. Using oligothiophene- containing supramolecules, we present systematic studies of critical thermodynamic parameters and kinetic pathway that govern the coassemblies of BCP and strongly interacting small molecules. A number of potentially useful morphologies for optoelectronic materials, including a nanoscopic network of oligothiophene and nanoscopic crystalline lamellae, were obtained by varying the assembly pathway. Hierarchical coassemblies of oligothiophene and BCP, rather than macrophase separation, can be obtained. Crystallization of the oligothiophene not only induces chain stretching of the BCP block the oligothiophene is hydrogen bonded to but also changes the conformation of the other BCP coil block. This leads to an over 70% change in the BCP periodicity (e.g., from 31 to 53 nm) as the oligothiophene changes from a melt to a crystalline state, which provides access to a large BCP periodicity using fairly low molecular weight BCP. The present studies have demonstrated the experimental feasibility of generating thermoresponsive materials that convert heat into mechanical energy. Incorporating strongly interacting small molecules into BCP supramolecules effectively increases the BCP periodicity and may also open new opportunities to tailor their optical properties without the need for high molecular weight BCP. © 2012 American Chemical Society.

  12. Fixman compensating potential for general branched molecules

    Energy Technology Data Exchange (ETDEWEB)

    Jain, Abhinandan, E-mail: Abhi.Jain@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, California 91109 (United States); Kandel, Saugat; Wagner, Jeffrey; Larsen, Adrien; Vaidehi, Nagarajan, E-mail: nvaidehi@coh.org [Division of Immunology, Beckman Research Institute of the City of Hope, Duarte, California 91010 (United States)

    2013-12-28

    The technique of constraining high frequency modes of molecular motion is an effective way to increase simulation time scale and improve conformational sampling in molecular dynamics simulations. However, it has been shown that constraints on higher frequency modes such as bond lengths and bond angles stiffen the molecular model, thereby introducing systematic biases in the statistical behavior of the simulations. Fixman proposed a compensating potential to remove such biases in the thermodynamic and kinetic properties calculated from dynamics simulations. Previous implementations of the Fixman potential have been limited to only short serial chain systems. In this paper, we present a spatial operator algebra based algorithm to calculate the Fixman potential and its gradient within constrained dynamics simulations for branched topology molecules of any size. Our numerical studies on molecules of increasing complexity validate our algorithm by demonstrating recovery of the dihedral angle probability distribution function for systems that range in complexity from serial chains to protein molecules. We observe that the Fixman compensating potential recovers the free energy surface of a serial chain polymer, thus annulling the biases caused by constraining the bond lengths and bond angles. The inclusion of Fixman potential entails only a modest increase in the computational cost in these simulations. We believe that this work represents the first instance where the Fixman potential has been used for general branched systems, and establishes the viability for its use in constrained dynamics simulations of proteins and other macromolecules.

  13. Graphical models for inferring single molecule dynamics

    Directory of Open Access Journals (Sweden)

    Gonzalez Ruben L

    2010-10-01

    Full Text Available Abstract Background The recent explosion of experimental techniques in single molecule biophysics has generated a variety of novel time series data requiring equally novel computational tools for analysis and inference. This article describes in general terms how graphical modeling may be used to learn from biophysical time series data using the variational Bayesian expectation maximization algorithm (VBEM. The discussion is illustrated by the example of single-molecule fluorescence resonance energy transfer (smFRET versus time data, where the smFRET time series is modeled as a hidden Markov model (HMM with Gaussian observables. A detailed description of smFRET is provided as well. Results The VBEM algorithm returns the model’s evidence and an approximating posterior parameter distribution given the data. The former provides a metric for model selection via maximum evidence (ME, and the latter a description of the model’s parameters learned from the data. ME/VBEM provide several advantages over the more commonly used approach of maximum likelihood (ML optimized by the expectation maximization (EM algorithm, the most important being a natural form of model selection and a well-posed (non-divergent optimization problem. Conclusions The results demonstrate the utility of graphical modeling for inference of dynamic processes in single molecule biophysics.

  14. Stokes-attenuated tunneling ionization of molecules

    Science.gov (United States)

    Kornev, Aleksei S.; Zon, Boris A.

    2018-03-01

    We set forth the quantum theory of ionic vibrational-level population by means of tunneling ionization of a molecule. Specific calculations are carried out for the H2 molecule. The results are in qualitative agreement with the experimental data [X. Urbain et al., Phys. Rev. Lett. 92, 163004 (2004), 10.1103/PhysRevLett.92.163004]. Our account for the excited vibrational levels reveals an interplay of two tendencies which contribute to the ionization rate: (i) It decreases due to additional energy absorption needed to populate these states and (ii) it increases together with the Franck-Condon factors which are large for these states. We show that these two tendencies practically compensate each other. The average quantitative disagreement between the theory and experiment amounts to ˜30 %. The same disagreement takes place when using the frozen approximation for the description of the nuclei motion. We demonstrated that the light-dressing effect for H2 leads to the dependence of the ionization rate on the angle between the molecule axis and the polarization vector of the radiation.

  15. Electron attachment to the phthalide molecule

    Energy Technology Data Exchange (ETDEWEB)

    Asfandiarov, N. L. [Institute of Molecule and Crystal Physics, Ufa Research Centre, Russian Academy of Sciences, Prospect Oktyabrya 151, 450075 Ufa (Russian Federation); Bashkir State Pedagogical University, Oktyabrskoy Revolutsii St., 3a, 450000 Ufa (Russian Federation); Pshenichnyuk, S. A. [Institute of Molecule and Crystal Physics, Ufa Research Centre, Russian Academy of Sciences, Prospect Oktyabrya 151, 450075 Ufa (Russian Federation); St.-Petersburg State University, Uljanovskaja, 1, 198504 St.-Petersburg (Russian Federation); Vorob’ev, A. S.; Nafikova, E. P. [Institute of Molecule and Crystal Physics, Ufa Research Centre, Russian Academy of Sciences, Prospect Oktyabrya 151, 450075 Ufa (Russian Federation); Lachinov, A. N. [Bashkir State Pedagogical University, Oktyabrskoy Revolutsii St., 3a, 450000 Ufa (Russian Federation); Kraikin, V. A. [Institute of Organic Chemistry, Ufa Research Centre, Russian Academy of Sciences, Prospect Oktyabrya 59, 450075 Ufa (Russian Federation); Modelli, A. [Dipartimento di Chimica “G. Ciamician,” Universitá di Bologna, Via Selmi 2, 40126 Bologna (Italy); Centro Interdipartimentale di Ricerca in Scienze Ambientali (CIRSA), Universitá di Bologna, Via S. Alberto 163, 48123 Ravenna (Italy)

    2015-05-07

    Phthalide, the simplest chain of conductive polymer thin film, was investigated by means of Electron Transmission Spectroscopy, Negative Ion Mass Spectrometry, and density functional theory quantum chemistry. It has been found that formation of gas-phase long-lived molecular anions of phthalide around 0.7 eV takes place through cleavage of a C–O bond of the pentacyclic ring of the parent molecular anion to give a vibrationally excited (electronically more stable) open-ring molecular anion. The energy of the transition state for ring opening of the parent negative ion is calculated to be 0.65 eV above the neutral ground state of the molecule. The energy (2.64 eV) evaluated for the corresponding transition state in the neutral molecule is much higher, so that the process of electron detachment from the anion must lead to a neutral molecule with its initial pentacyclic structure. The average lifetime of the molecular negative ions formed at an electron energy of 0.75 eV and 80 °C is measured to be about 100 μs. The known switching effect of thin phthalide films could stem from the presence of a similar open/closed transition state also in the polymer.

  16. [Aerodynamic focusing of particles and heavy molecules

    International Nuclear Information System (INIS)

    de la Mora, J.F.

    1990-01-01

    By accelerating a gas containing suspended particles or large molecules through a converging nozzle, the suspended species may be focused and therefore used to write fine lines on a surface. Our objective was to study the limits on how narrow this focal region could be as a function of particle size. We find that, for monodisperse particles with masses m p some 3.6 x 10 5 times larger than the molecular mass m of the carrier gas (diameters above some 100 angstrom), there is no fundamental obstacle to directly write submicron features. However, this conclusion has been verified experimentally only with particles larger than 0.1 μm. Experimental, theoretical and numerical studies on the defocusing role of Brownian motion for very small particles or heavy molecules have shown that high resolution (purely aerodynamic) focusing is impossible with volatile molecules whose masses are typically smaller than 1000 Dalton. For these, the minimal focal diameter after optimization appears to be 5√(m/m p ) times the nozzle diameter d n . But combinations of focused lasers and aerodynamic focusing appear as promising for direct writing with molecular precursors. Theoretical and numerical schemes capable of predicting the evolution of the focusing beam, including Brownian motion effects, have been developed, although further numerical work would be desirable. 11 refs

  17. Structure and hydrodynamic properties of plectin molecules.

    Science.gov (United States)

    Foisner, R; Wiche, G

    1987-12-05

    Plectin is a cytoskeletal, high molecular weight protein of widespread and abundant occurrence in cultured cells and tissues. To study its molecular structure, the protein was purified from rat glioma C6 cells and subjected to chemical and biophysical analyses. Plectin's polypeptide chains have an apparent molecular weight of 300,000, as shown by one-dimensional sodium dodecyl sulfate/polyacrylamide electrophoresis. Cross-linking of non-denatured plectin in solution with dimethyl suberimidate and electrophoretic analyses on sodium dodecyl sulfate/agarose gels revealed that the predominant soluble plectin species was a molecule of 1200 X 10(3) Mr consisting of four 300 X 10(3) Mr polypeptide chains. Hydrodynamic properties of plectin in solution were obtained by sedimentation velocity centrifugation and high-pressure liquid chromatography analysis yielding a sedimentation coefficient of 10 S and a Stokes radius of 27 nm. The high f/fmin ratio of 4.0 indicated a very elongated shape of plectin molecules and an axial ratio of about 50. Shadowing and negative staining electron microscopy of plectin molecules revealed multiple domains: a rigid rod of 184 nm in length and 2 nm in diameter, and two globular heads of 9 nm diameter at each end of the rod. Circular dichroism spectra suggested a composition of 30% alpha-helix, 9% beta-structure and 61% random coil or aperiodic structure. The rod-like shape, the alpha-helix content as well as the thermal transition within a midpoint of 45 degrees C and the transition enthalpy (168 kJ/mol) of secondary structure suggested a double-stranded, alpha-helical coiled coil rod domain. Based on the available data, we favor a model of native plectin as a dumb-bell-like association of four 300 X 10(3) Mr polypeptide chains. Electron microscopy and turbidity measurements showed that plectin molecules self-associate into various oligomeric states in solutions of nearly physiological ionic strength. These interactions apparently involved

  18. La vente des biens nationaux à la fin du XVIIIe siècle, nouvelle donne pour la ville The sale of national assets at the end of the 18th century – a gift to the city

    Directory of Open Access Journals (Sweden)

    François Antoine

    2009-05-01

    Full Text Available À la fin de l’Ancien Régime, les villes des Pays-Bas gardaient les traits de villes médiévales sans ordre et faites d’entrelacs de rues et de ruelles. Le caractère corporatif de la production limitait la présence de grands ensembles industriels et les couvents et leurs jardins occupaient une grande partie de la superficie intra et extra muros des cités. Par ailleurs, l’Église était propriétaire d’un important parc immobilier de petites demeures adossées à des églises jusqu’aux importants refuges d’abbayes dominant dans les campagnes de vastes espaces fonciers. Durant la deuxième moitié du xviiie, les autorités habsbourgeoises menèrent une politique tendant à moderniser les villes en faisant, en autres, tomber les enceintes et en donnant une nouvelle affectation aux couvents contemplatifs supprimés. La Révolution française bouleversa ces ensembles urbains en libérant d’un coup une masse très importante de biens immobiliers qui appartenait à l’Église et en modifiant radicalement les modes de production par la suppression des corporations de métiers. La bourgeoisie principalement négociante réussi habilement tirer tous les profits de cette nouvelle donne. Cet effet d’aubaine contribua grandement à faire passer nos régions dans un nouveau stade de leur démarrage industriel.At the end of the Ancien Régime, the towns of the Netherlands retained the characteristics of medieval towns, without any order and consisting of warrens of streets and alleys. The corporative nature of production limited the presence of major industrial complexes and the monasteries and convents, together with their gardens, covered a large part of the urban areas both within and outside city walls. In addition, the church had important property holdings, ranging from small residential properties attached to churches to major abbey residences dominating vast countryside estates. During the second half of the 18th century, the

  19. La participation des acteurs locaux à l’élaboration et l’évaluation des politiques publiques de développement durable  en Nouvelle-Calédonie

    Directory of Open Access Journals (Sweden)

    Séverine Bouard

    2008-11-01

    Full Text Available L’objet de cet article est d’explorer les conditions et l’opérationnalité d’une réflexion participative sur le développement durable et ses implications pour élaborer et évaluer des politiques publiques de développement. Après une présentation succincte des controverses dont fait l’objet le concept de développement durable à l’échelle mondiale, nous tenterons de préciser les enjeux de durabilité dans le contexte de la Nouvelle-Calédonie. L’entrée privilégie les articulations entre les trois dimensions de la durabilité, en s’appuyant sur les formes localement perçues de la performance économique, de l’intégrité de l’environnement et de l’équité sociale. Pour illustrer ces enjeux, nous nous intéressons plus précisément à la gestion sociale des impacts d’un important projet industriel d’extraction et de traitement du nickel dans la province Nord de Nouvelle-Calédonie. L’article décrit ensuite les principes à respecter pour la mise en place d’un suivi évaluation concerté entre les différents acteurs, susceptible de faciliter la prise en charge de cette transversalité et la gestion sociale des impacts du projet. Nous partons pour cela des acquis d’un programme de recherche portant sur l’élaboration d’une méthode de suivi évaluation participatif des programmes de développement local en province Nord. Enfin, nous insisterons sur les contraintes à l’efficacité et à la pérennité de dispositifs réellement participatifs, mais aussi à l’application des principes du développement durable, notamment dans le contexte du Pacifique insulaire.The aim of this article is to investigate the conditions and the interests of a participatory reflexion on the sustainable development and its consequences to draw up and to assess development policies. After a brief display of the controversies carried out by the use and sense of the “sustainable development”, we explain what is at

  20. Study of new structures adapted to gas-graphite and gas-heavy water reactors; Etude de structures nouvelles adaptees aux reacteurs graphite-gaz et eau lourde-gaz

    Energy Technology Data Exchange (ETDEWEB)

    Martin, R; Roche, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    'EDF d'une part, les conclusions des etudes et essais effectues hors pile d'autre part, conduisent a un changement considerable de la physionomie des reacteurs de la filiere Graphite-Gaz, Les principales modifications envisagees sont analysees dans la communication. L'adoption d'un element combustible annulaire et d'un soufflage descendant permettront d'accroitre considerablement la puissance specifique et la puissance developpee par canal; il en resultera une reduction sensible du nombre des canaux et un accroissement correlatif de la maille du reseau - L'empilement de graphite devra etre adapte a ces nouvelles conditions - Des raisons de securite conduisent a generaliser l'emploi du beton precontraint pour la construction du caisson; elles pourront amener a integrer a l'interieur de celui-ci les echangeurs et l'appareil de manutention du combustible (dispositif dit: 'en grenier'). Une maquette en vraie grandeur de ce grenier a ete construite a Saclay avec la participation d'EURATOM; les resultats d'exploitation en sont presentes, ainsi que des idees de barres de controle de conception nouvelle. En ce qui concerne la filiere Eau-Lourde-Gaz, les etudes sont poursuivies dans deux voies principales; la premiere, qui conserverait l'usage de tubes de force horizontaux, tient compte de l'experience acquise au cours de la construction du reacteur EL4 dont elle constituerait une extrapolation; la seconde, inspiree des etudes poursuivies au titre de la filiere Graphite-Gaz, ferait appel a un caisson en beton precontraint pour tenir la pression, le moderateur etant sensiblement a la pression du fluide refrigerant et le combustible etant dispose dans des canaux verticaux. Les merites respectifs de ces deux variantes sont analyses dans la communication. (auteurs)

  1. The Importance of the Idealist Discourse in Defence of American Foreign Policy Initiatives: beyond rhetoric towards a new form of imperialism L’importance du discours idéaliste pour défendre la politique étrangère américaine : vers une nouvelle forme d’impérialisme

    Directory of Open Access Journals (Sweden)

    Andrew Ives

    2009-10-01

    Full Text Available Les États-Unis font rarement appel à un discours basé sur la défense de leurs propres intérêts nationaux pour défendre sa politique étrangère. Dans leur discours officiel, ils tentent plutôt de subordonner l’intérêt national aux objectifs plus nobles de défendre les droits de l’homme ou la démocratie. Cet article commence par retracer les origines de ce discours idéaliste américain. Puis, il tente d’analyser le rôle important joué par ce discours, suggérant qu’il est révélateur d’une nouvelle forme d’impérialisme. Elle est nouvelle dans la mesure où l’État-nation dominant se présente comme l’incarnation de la démocratie libérale faisant en sorte que ses propres intérêts coïncident avec ceux de la démocratie libérale. Le discours idéaliste serait, selon l’auteur, non pas une façade, mais plutôt un élément essentiel d’une nouvelle forme d’impérialisme car la relation étroite qui s’établit entre démocratie libérale et interventionnisme américain renforcerait les intérêts du capitalisme moderne.  

  2. Spectral simulations of polar diatomic molecules immersed in He clusters: application to the ICl (X) molecule

    International Nuclear Information System (INIS)

    Villarreal, P; Lara-Castells, M P de; Prosmiti, R; Delgado-Barrio, G; Lopez-Duran, D; Gianturco, F A; Jellinek, J

    2007-01-01

    A recently developed quantum-chemistry-like methodology to study molecules solvated in atomic clusters is applied to the ICl (iodine chloride) polar diatomic molecule immersed in clusters of He atoms. The atoms of the solvent clusters are treated as the 'electrons' and the solvated molecule as a structured 'nucleus' of the combined solvent-solute system. The helium-helium and helium-dopant interactions are represented by parametrized two-body and ab initio three-body potentials, respectively. The ground-state wavefunctions are used to compute the infrared (IR) spectra of the solvated molecule. In agreement with the experimental observations, the computed spectra exhibit considerable differences depending on whether the solvent cluster is comprised of bosonic ( 4 He) or fermionic ( 3 He) atoms. The source of these differences is attributed to the different spin-statistics of the solvent clusters. The bosonic versus fermionic nature of the solvent is reflected in the IR absorption selection rules. Only P and R branches with single state transitions appear in the spectrum when the molecule is solvated in a bosonic cluster. On the other hand, when the solvent represents a fermionic environment, quasi-degenerate multiplets of spin states contribute to each branch and, in addition, the Q-branch becomes also allowed. Combined, these two factors explain the more congested nature of the spectrum in the fermionic case

  3. Study of the electronic properties of organic molecules within a metal-molecule-metal junction

    International Nuclear Information System (INIS)

    Lambert, Mathieu

    2003-01-01

    This ph-D thesis is about electronic transport through organic molecules inserted in a metal molecule-metal junction. We describe first a simple process to prepare sub-3 nm gaps by controllable breakage (under an electrical stress) of gold wires lithographed on a SiO 2 Si substrate at low temperature (4.2 K). We show that the involved mechanism is thermally assisted electromigration. We observe that current-voltage (I-V) characteristics of resulting electrodes are stable up to ∼5 V. which gives access to the well-known Fowler-Nordheim regime in the I-V, allowing an accurate characterisation of the gap size. The average gap is found lo be between 1.5 nm in width and 2.5 eV in height. Molecules and nanoparticles have then been inserted in the junction in the case of nanoparticles for example. The resulting IV clearly shows the suppression of electrical current at low bias known as Coulomb blockade. Characteristic of single-electron tunnelling through nanometer-sized structures, finally we fabricated a single-electron tunneling device based on Au nanoparticles connected to the electrodes via terthiophene (T3) molecule. We use the silicon substrate, separated from the planar structure by a silicon oxide of 200 nm, as an electrostatic gate and observed clear current modulation with possible signature of the transport properties of the terthiophene molecules. (author) [fr

  4. Raman scattering mediated by neighboring molecules

    Science.gov (United States)

    Williams, Mathew D.; Bradshaw, David S.; Andrews, David L.

    2016-05-01

    Raman scattering is most commonly associated with a change in vibrational state within individual molecules, the corresponding frequency shift in the scattered light affording a key way of identifying material structures. In theories where both matter and light are treated quantum mechanically, the fundamental scattering process is represented as the concurrent annihilation of a photon from one radiation mode and creation of another in a different mode. Developing this quantum electrodynamical formulation, the focus of the present work is on the spectroscopic consequences of electrodynamic coupling between neighboring molecules or other kinds of optical center. To encompass these nanoscale interactions, through which the molecular states evolve under the dual influence of the input light and local fields, this work identifies and determines two major mechanisms for each of which different selection rules apply. The constituent optical centers are considered to be chemically different and held in a fixed orientation with respect to each other, either as two components of a larger molecule or a molecular assembly that can undergo free rotation in a fluid medium or as parts of a larger, solid material. The two centers are considered to be separated beyond wavefunction overlap but close enough together to fall within an optical near-field limit, which leads to high inverse power dependences on their local separation. In this investigation, individual centers undergo a Stokes transition, whilst each neighbor of a different species remains in its original electronic and vibrational state. Analogous principles are applicable for the anti-Stokes case. The analysis concludes by considering the experimental consequences of applying this spectroscopic interpretation to fluid media; explicitly, the selection rules and the impact of pressure on the radiant intensity of this process.

  5. Magnetic Molecules from Chemist's Point of View

    Science.gov (United States)

    Hendrickson, David

    2002-03-01

    A single-molecule magnet (SMM) is a molecule that functions as a nanoscale, single-domain magnetic particle that, below its blocking temperature, exhibits magnetization hysteresis [1]. SMMs have attracted considerable interest because they : (1) can serve as the smallest nanomagnet, monodisperse in size, shape and anisotropy; (2) exhibit quantum tunneling of magnetization (QTM); and (3) may function as memory devices in a quantum computer. SMM’s are synthetically designed nanomagnets, built from a core containing metal ion unpaired spin carriers bridged by oxide or other simple ions which is surrounded by organic ligands. Many systematic changes can be made in the structure of these molecular nanomagnets. Manganese-containing SMM’s are known with from Mn4 to Mn_30 compositions. The magnetic bistability, which is desirable for data storage applications, is achievable at temperatures below 3K. The largest spin of the ground state of a SMM is presently S = 13. Appreciable largely uniaxial magnetoanisotropy in the ground state leads to magnetic bistability. Rather than a continuum of higher energy states separating the “spin-up” and “spin-down” ground states, the quantum nature of the molecular nanomagnets result in a well defined ladder of discrete quantum states. Recent studies have definitively shown that, under conditions that can be controlled via the application of external perturbations, quantum tunneling may occur through the energy separating the “spin-up” and “spin-down” states. The tunneling is due to weak symmetry breaking perturbations that give rise to long-lived quantum states consisting of coherent superpositions of the “spin-up” and “spin-down” states. It is the ability to manipulate these coherent states that makes SMMs particularly attractive for quantum computation. Reference: [1] G. Christou, D. Gatteschi, D. N. Hendrickson, R. Sessoli, “Single-molecule Magnets”, M.R.S. Bull. 25, 66 (2001).

  6. Electron Impact Excitation-Ionization of Molecules

    Science.gov (United States)

    Ali, Esam Abobakr A.

    In the last few decades, the study of atomic collisions by electron-impact has made significant advances. The most difficult case to study is electron impact ionization of molecules for which many approximations have to be made and the validity of these approximations can only be checked by comparing with experiment. In this thesis, I have examined the Molecular three-body distorted wave (M3DW) or Molecular four-body distorted wave (M4DW) approximations for electron-impact ionization. These models use a fully quantum mechanical approach where all particles are treated quantum mechanically and the post collision interaction (PCI) is treated to all orders of perturbation. These electron impact ionization collisions play central roles in the physics and chemistry of upper atmosphere, biofuel, the operation of discharges and lasers, radiation induced damage in biological material like damage to DNA by secondary electrons, and plasma etching processes. For the M3DW model, I will present results for electron impact single ionization of small molecules such as Water, Ethane, and Carbon Dioxide and the much larger molecules Tetrahydrofuran, phenol, furfural, 1-4 Benzoquinone. I will also present results for the four-body problem in which there are two target electrons involved in the collision. M4DW results will be presented for dissociative excitation-ionization of orientated D2. I will show that M4DW calculations using a variational wave function for the ground state that included s- and p- orbital states give better agreement to the experimental measurements than a ground state approximated as a product of two 1s-type Dyson orbitals.

  7. Studies of interstellar vibrationally-excited molecules

    International Nuclear Information System (INIS)

    Ziurys, L.M.; Snell, R.L.; Erickson, N.R.

    1986-01-01

    Several molecules thus far have been detected in the ISM in vibrationally-excited states, including H 2 , SiO, HC 3 N, and CH 3 CN. In order for vibrational-excitation to occur, these species must be present in unusually hot and dense gas and/or where strong infrared radiation is present. In order to do a more thorough investigation of vibrational excitation in the interstellar medium (ISM), studies were done of several mm-wave transitions originating in excited vibrational modes of HCN, an abundant interstellar molecule. Vibrationally-excited HCN was recently detected toward Orion-KL and IRC+10216, using a 12 meter antenna. The J=3-2 rotational transitions were detected in the molecule's lowest vibrational state, the bending mode, which is split into two separate levels, due to l-type doubling. This bending mode lies 1025K above ground state, with an Einstein A coefficient of 3.6/s. The J=3-2 line mode of HCN, which lies 2050K above ground state, was also observed toward IRC+10216, and subsequently in Orion-KL. Further measurements of vibrationally-excited HCN were done using a 14 meter telescope, which include the observations of the (0,1,0) and (0,2,0) modes towards Orion-KL, via their J=3-2 transitions at 265-267 GHz. The spectrum of the J=3-2 line in Orion taken with the 14 meter telescope, is shown, along with a map, which indicates that emission from vibrationally-excited HCN arises from a region probably smaller than the 14 meter telescope's 20 arcsec beam

  8. Energy distribution in dissociations of polyatomic molecules

    International Nuclear Information System (INIS)

    Koernig, S.A.

    1989-01-01

    In this thesis studies are reported of fragmentation processes in polyatomic molecules. In order to find out which dessocaciation reactions take place, how they are brought about by the internal energy of the reactant, and to investigate the structure of the dissociating 'transition state', the fragment mass and the corresponding kinetic energy release (KER) are determined by differential translational spectroscopy using a position and time sensitive two-particle coincidence detector. The results are interpreted using the statistical theory of unimolecular dissociation. It turns out that the standard assumptions of the theory, especially in calculating KER-distributions, are not realistic in all molecules considered. Dissociation is induced by the neutralization with alkali metal vapour. In ch. 2 the experimental method and the analysis of the data (dissociation pathways, branching ratios and ε-d-distributions) are introduced and exemplified by measurements of cyclohexane, which represents the upper limit in precursor and fragment mass accessible in the apparatus. In ch. 3 a study is reported of the molecules methylchloride (CH 3 Cl) and the acetylradical (CH 3 CO). In spite of their similar geometric structures, completely different dissociation mechanisms have been found. Methylchloride dissociates via a repulsive state; acetyl radicals show energy scrambling. The energy distribution from dissociating acetyl exemplifies dynamical effects in the dissociation. In ch. 4 an investigation of a number of prototype hydrocarbons is presented. The dissociation pathways of several small linear alkanes indicate that neutralization takes place to unknown repulsive potentials, of which the position and steepness are determined from the kinetic energy release. (author). 118 refs.; 40 figs.; 5 tabs

  9. What are nuclear molecules?: past and present

    Energy Technology Data Exchange (ETDEWEB)

    Hess, P.O [Universidad Nacional Autonoma de Mexico, Mexico, D.F (Mexico)

    2001-04-01

    A brief history of nuclear molecules, which was discovered for the first time in 1960, is presented. A couple of simple models for their description are discussed, as the Double Resonance Mechanisms and the Two-Center Shell Model. These classical nuclear molecules live only about the order of 10{sup -2}1 seconds, barely sufficient to orbit once around each other. Recently, a new type of nuclear molecules was discovered, with three clusters, which live of the order of 10{sup -1}3 seconds. We discuss shortly the experiment and the conclusions of it. At the end, we present a geometric model and apply it to {sup 9}6Sr + {sup 1}0Be + {sup 1}46Ba observed in the cold fission decay of {sup 2}52 Cf. [Spanish] Se presenta una breve historia de moleculas nucleares, que fueron identificadas por primera vez en 1960. Unos modelos sencillos, para su descripcion, son discutidos, como el Mecanismo de Doble Resonancia y Modelo de Dos Centros. Estas moleculas clasicas solo viven un orden de 10{sup -2}1 segundos, apenas suficiente para dar una vuelta. Recientemente se han descubierto moleculas nucleares de tres cumulos que viven un orden de 10{sup -1}3 segundos. Se discute un poco el experimento y las conclusiones de el. Al final se presenta un modelo geometrico que aplicamos a {sup 9}6Sr + {sup 1}0Be + {sup 1}46Ba, observado en el decaimiento frio de {sup 2}52 Cf.

  10. Raman scattering mediated by neighboring molecules

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Mathew D.; Bradshaw, David S.; Andrews, David L., E-mail: david.andrews@physics.org [School of Chemistry, University of East Anglia, Norwich NR4 7TJ (United Kingdom)

    2016-05-07

    Raman scattering is most commonly associated with a change in vibrational state within individual molecules, the corresponding frequency shift in the scattered light affording a key way of identifying material structures. In theories where both matter and light are treated quantum mechanically, the fundamental scattering process is represented as the concurrent annihilation of a photon from one radiation mode and creation of another in a different mode. Developing this quantum electrodynamical formulation, the focus of the present work is on the spectroscopic consequences of electrodynamic coupling between neighboring molecules or other kinds of optical center. To encompass these nanoscale interactions, through which the molecular states evolve under the dual influence of the input light and local fields, this work identifies and determines two major mechanisms for each of which different selection rules apply. The constituent optical centers are considered to be chemically different and held in a fixed orientation with respect to each other, either as two components of a larger molecule or a molecular assembly that can undergo free rotation in a fluid medium or as parts of a larger, solid material. The two centers are considered to be separated beyond wavefunction overlap but close enough together to fall within an optical near-field limit, which leads to high inverse power dependences on their local separation. In this investigation, individual centers undergo a Stokes transition, whilst each neighbor of a different species remains in its original electronic and vibrational state. Analogous principles are applicable for the anti-Stokes case. The analysis concludes by considering the experimental consequences of applying this spectroscopic interpretation to fluid media; explicitly, the selection rules and the impact of pressure on the radiant intensity of this process.

  11. Studies of atmospheric molecules by multiphoton spectroscopy

    International Nuclear Information System (INIS)

    Johnson, P.M.

    1990-12-01

    Resonance ionization processes can play an important role in understanding molecules important in combustion processes. They are a reflection of the dynamic as well as the static properties of atomic and molecular species. Due to the sequential or quasisequential nature of photon absorption in resonant multiphoton events, the lifetimes of the intermediate states play an essential role in the overall cross-sections if they are short enough to be competitive with subsequent photon interactions. In molecules this is particularly important because there are many dissociative and other radiationless pathways which can contribute to a competitive channel. Under those conditions it should be possible to obtain information about the nature of the dynamics of the intermediate state form the multiphoton ionization process. This will involve looking at not only the ionization cross-section but also other observables such as the kinetic energy of the ejected electrons and possibly the distribution of fragment ions produced in the ionization event. Whether the ionization amplitude is affected or not, the time scales of the dynamic events which alter the ionization path can vary over a large range from the femtoseconds of dissociation to the microseconds of some radiationless transitions in large molecules. When the competing channel has a time scale shorter than the laser pulse length, the kinetics of the ionization are intimately tied into the precise nature of the laser pulse. For time scales longer than the laser pulse, pump-probe ionization schemes in which one laser prepares a state while another does the ionization provide a particularly simple method for investigating the dynamics of the intermediate state. Here the author discusses examples from each of these regimes. CO 2 and pyrazine are examined. 6 refs., 6 figs

  12. Deep learning for single-molecule science

    Science.gov (United States)

    Albrecht, Tim; Slabaugh, Gregory; Alonso, Eduardo; Al-Arif, SM Masudur R.

    2017-10-01

    Exploring and making predictions based on single-molecule data can be challenging, not only due to the sheer size of the datasets, but also because a priori knowledge about the signal characteristics is typically limited and poor signal-to-noise ratio. For example, hypothesis-driven data exploration, informed by an expectation of the signal characteristics, can lead to interpretation bias or loss of information. Equally, even when the different data categories are known, e.g., the four bases in DNA sequencing, it is often difficult to know how to make best use of the available information content. The latest developments in machine learning (ML), so-called deep learning (DL) offer interesting, new avenues to address such challenges. In some applications, such as speech and image recognition, DL has been able to outperform conventional ML strategies and even human performance. However, to date DL has not been applied much in single-molecule science, presumably in part because relatively little is known about the ‘internal workings’ of such DL tools within single-molecule science as a field. In this Tutorial, we make an attempt to illustrate in a step-by-step guide how one of those, a convolutional neural network (CNN), may be used for base calling in DNA sequencing applications. We compare it with a SVM as a more conventional ML method, and discuss some of the strengths and weaknesses of the approach. In particular, a ‘deep’ neural network has many features of a ‘black box’, which has important implications on how we look at and interpret data.

  13. Flavonoids – Small Molecules, High Hopes

    Directory of Open Access Journals (Sweden)

    Sandu Mariana

    2017-07-01

    Full Text Available This brief review takes a look at flavonoids, a wide class of polyphenols, which are regarded as plant secondary metabolites. Their roles in plants are diverse and little understood. They can act as growth hormone modulators, phytoalexins, they offer UV protection, contribute to pollen viability and can function as signaling molecules in establishing symbiotic relationships. Flavonoids were also found to have a range of beneficial effects for the human body. Their anticancer, antioxidant, anti-inflammatory and cardioprotective activity, as well as their antibacterial, antiviral and antihelmintic properties make them promising candidates for the design of new drugs.

  14. Excipients used in lyophilization of small molecules

    Directory of Open Access Journals (Sweden)

    Ankit Baheti

    2010-03-01

    Full Text Available This review deals with the excipients used in various lyophilized formulations of small molecules. The role of excipients such as bulking agents, buffering agents, tonicity modifiers, antimicrobial agents, surfactants and co-solvents has been discussed. Additionally, a decision making process for their incorporation into the formulation matrix has been proposed. A list of ingredients used in lyophilized formulations marketed in USA has been created based on a survey of the Physician Desk Reference (PDR and the Handbook on Injectable Drugs. Information on the recommended quantities of various excipients has also been provided, based on the details given in the Inactive Ingredient Guide (IIG.

  15. Molecular-beam spectroscopy of interhalogen molecules

    International Nuclear Information System (INIS)

    Sherrow, S.A.

    1983-08-01

    A molecular-beam electric-resonance spectrometer employing a supersonic nozzle source has been used to obtain hyperfine spectra of 79 Br 35 Cl. Analyses of these spectra and of microwave spectra published by other authors have yielded new values for the electric dipole moment and for the nuclear quadrupole coupling constants in this molecule. The new constants are significantly different from the currently accepted values. Van der Waals clusters containing chlorine monofluoride have been studied under various expansion conditions by the molecular-beam electric-deflection method. The structural possibilities indicated by the results are discussed, and cluster geometries are proposed

  16. Memory effects in single-molecule spectroscopy

    International Nuclear Information System (INIS)

    Schmitt, Daniel T.; Schulz, Michael; Reineker, Peter

    2007-01-01

    From the time series of LH2 optical single-molecule fluorescence excitation spectra of Rhodospirillum molischianum the memory function of the Mori-Zwanzig equation for the optical intensity is derived numerically. We show that the time dependence of the excited states is determined by at least three different non-Markovian stochastic processes with decay constants for the Mori-Zwanzig kernel on the order of 1-5min -1 . We suggest that this decay stems from the conformational motion of the protein scaffold of LH2

  17. Self-dual monopoles and toda molecules

    Science.gov (United States)

    Ganoulis, N.; Goddard, P.; Olive, D.

    1982-07-01

    Stable static solutions to a gauge field theory with a Higgs field in the adjoint representation and with vanishing self-coupling are self-dual in the sense of Bogomolny. Leznov and Saveliev showed that a specific form of spherical symmetry reduces these equations to a modified form of the Toda molecule equations associated with the overall gauge symmetry G. Values of the constants of integration are found in terms of the distant Higgs field, guaranteeing regularity of the solution at the origin. The expressions hold for any simple Lie group G, depending on G via its root system.

  18. Gaseous Electronics Tables, Atoms, and Molecules

    CERN Document Server

    Raju, Gorur Govinda

    2011-01-01

    With the constant emergence of new research and application possibilities, gaseous electronics is more important than ever in disciplines including engineering (electrical, power, mechanical, electronics, and environmental), physics, and electronics. The first resource of its kind, Gaseous Electronics: Tables, Atoms, and Molecules fulfills the author's vision of a stand-alone reference to condense 100 years of research on electron-neutral collision data into one easily searchable volume. It presents most--if not all--of the properly classified experimental results that scientists, researchers,

  19. Quantum theory of anharmonic effects in molecules

    CERN Document Server

    Kazakov, Konstantin V

    2012-01-01

    Presented in a clear and straightforward analysis, this book explores quantum mechanics and the application of quantum mechanics to interpret spectral phenomena. Specifically, the book discusses the relation between spectral features in mid or rear infrared regions, or in Raman scattering spectrum, and interactions between molecules or molecular species such as molecular ions, and their respective motions in gaseous or crystalline conditions. Beginning with an overview of conventional methods and problems which arise in molecular spectroscopy, the second half of the book suggests original t

  20. Matter-Wave Optics of Diatomic Molecules

    Science.gov (United States)

    2012-10-23

    81.013802 10/11/2012 32.00 Swati Singh , Pierre Meystre. Atomic probe Wigner tomography of a nanomechanical system, Physical Review A, (04 2010): 41804...PhysRevA.78.041801 10/11/2012 3.00 S. Singh , M. Bhattacharya, O. Dutta, P. Meystre. Coupling Nanomechanical Cantilevers to Dipolar Molecules...degenerate matter waves, Physical Review A, (02 2009): 0. doi: 10.1103/PhysRevA.79.023622 10/11/2012 10.00 M. Bhattacharya, S. Singh , P. -L. Giscard

  1. Structure of molecules and internal rotation

    CERN Document Server

    Mizushima, San-Ichiro

    1954-01-01

    Structure of Molecules and Internal Rotation reviews early studies on dihalogenoethanes. This book is organized into two parts encompassing 8 chapters that evaluate the Raman effect in ethane derivatives, the energy difference between rotational isomers, and the infrared absorption of ethane derivatives. Some of the topics covered in the book are the potential barrier to internal rotation; nature of the hindering potential; entropy difference between the rotational isomers; internal rotation in butane, pentane, and hexane; and internal rotation in long chain n-paraffins. Other chapters deal wi

  2. Thermally induced charge current through long molecules

    Science.gov (United States)

    Zimbovskaya, Natalya A.; Nitzan, Abraham

    2018-01-01

    In this work, we theoretically study steady state thermoelectric transport through a single-molecule junction with a long chain-like bridge. Electron transmission through the system is computed using a tight-binding model for the bridge. We analyze dependences of thermocurrent on the bridge length in unbiased and biased systems operating within and beyond the linear response regime. It is shown that the length-dependent thermocurrent is controlled by the lineshape of electron transmission in the interval corresponding to the HOMO/LUMO transport channel. Also, it is demonstrated that electron interactions with molecular vibrations may significantly affect the length-dependent thermocurrent.

  3. Small Molecules, Diversity and Great Expectations

    Indian Academy of Sciences (India)

    Small Molecules, Diversity and Great Expectations · PowerPoint Presentation · Slide 3 · Slide 4 · Slide 5 · Slide 6 · Slide 7 · Slide 8 · Slide 9 · Slide 10 · Slide 11 · Slide 12 · Slide 13 · Slide 14 · Slide 15 · Slide 16 · Slide 17 · Slide 18 · Slide 19 · Slide 20 · Slide 21 · Slide 22 · Slide 23 · Slide 24 · Slide 25 · Slide 26 · Slide 27.

  4. Aging-From molecules to populations

    DEFF Research Database (Denmark)

    Sander, Miriam; Avlund, Kirsten; Lauritzen, Martin

    2008-01-01

    of human aging. To foster interactions and collaboration between diverse scientists interested in the biochemical, physiological, epidemiological and psychosocial aspects of aging, The University of Copenhagen Faculty of Health Sciences recently organized and co-sponsored a workshop entitled Aging......-From Molecules to Populations. The following questions about human aging were discussed at the workshop: What is the limit of human life expectancy? What are the key indicators of human aging? What are the key drivers of human aging? Which genes have the greatest impact on human aging? How similar is aging...

  5. Bringing molecules back into molecular evolution.

    Directory of Open Access Journals (Sweden)

    Claus O Wilke

    Full Text Available Much molecular-evolution research is concerned with sequence analysis. Yet these sequences represent real, three-dimensional molecules with complex structure and function. Here I highlight a growing trend in the field to incorporate molecular structure and function into computational molecular-evolution work. I consider three focus areas: reconstruction and analysis of past evolutionary events, such as phylogenetic inference or methods to infer selection pressures; development of toy models and simulations to identify fundamental principles of molecular evolution; and atom-level, highly realistic computational modeling of molecular structure and function aimed at making predictions about possible future evolutionary events.

  6. Radiation produced by electrons incident on molecules

    International Nuclear Information System (INIS)

    Moehlman, G.R.

    1977-01-01

    The work described in this thesis deals with light intensity measurements of emission spectra (1850-9000 A) produced by a continuous or pulsed beam of monoenergetic electrons (0 - 2000 eV) incident on a variety of molecular gases like H 2 , D 2 , H 2 O, HCl, NH 3 and several hydrocarbons. The emission spectra are dominated by fluorescence from excited fragments produced via dissociative excitation, besides fluorescence from excited parent molecules themselves. The experimental results thus obtained are expressed in terms of emission cross sections and lifetimes

  7. Small organic molecule based flow battery

    Science.gov (United States)

    Huskinson, Brian; Marshak, Michael; Aziz, Michael J.; Gordon, Roy G.; Betley, Theodore A.; Aspuru-Guzik, Alan; Er, Suleyman; Suh, Changwon

    2018-05-08

    The invention provides an electrochemical cell based on a new chemistry for a flow battery for large scale, e.g., gridscale, electrical energy storage. Electrical energy is stored chemically at an electrochemical electrode by the protonation of small organic molecules called quinones to hydroquinones. The proton is provided by a complementary electrochemical reaction at the other electrode. These reactions are reversed to deliver electrical energy. A flow battery based on this concept can operate as a closed system. The flow battery architecture has scaling advantages over solid electrode batteries for large scale energy storage.

  8. The (e,2e) reaction in molecules

    International Nuclear Information System (INIS)

    Dey, S.; Dixon, A.; Teubner, P.J.O.; Weigold, E.

    1975-01-01

    The aplication of the (e,2e) technique is discussed in the framework of (e,2e) on molecular hydrogen. It is shown that the technique is sufficiently sensitive to distinguish between simple wavefunctions and those containing configuration interactions. By comparing the data on H 2 and D 2 is shown that the Born-Oppenheimer approximation is confirmed to an accuracy of about 3 per cent. The data is also used to contrast other methods of determining electron momentum distributions in molecules. Data on methane, carbon monoxide and molecular nitrogen is also presented. (author)

  9. Challenges for single molecule electronic devices with nanographene and organic molecules. Do single molecules offer potential as elements of electronic devices in the next generation?

    Science.gov (United States)

    Enoki, Toshiaki; Kiguchi, Manabu

    2018-03-01

    Interest in utilizing organic molecules to fabricate electronic materials has existed ever since organic (molecular) semiconductors were first discovered in the 1950s. Since then, scientists have devoted serious effort to the creation of various molecule-based electronic systems, such as molecular metals and molecular superconductors. Single-molecule electronics and the associated basic science have emerged over the past two decades and provided hope for the development of highly integrated molecule-based electronic devices in the future (after the Si-based technology era has ended). Here, nanographenes (nano-sized graphene) with atomically precise structures are among the most promising molecules that can be utilized for electronic/spintronic devices. To manipulate single small molecules for an electronic device, a single molecular junction has been developed. It is a powerful tool that allows even small molecules to be utilized. External electric, magnetic, chemical, and mechanical perturbations can change the physical and chemical properties of molecules in a way that is different from bulk materials. Therefore, the various functionalities of molecules, along with changes induced by external perturbations, allows us to create electronic devices that we cannot create using current top-down Si-based technology. Future challenges that involve the incorporation of condensed matter physics, quantum chemistry calculations, organic synthetic chemistry, and electronic device engineering are expected to open a new era in single-molecule device electronic technology.

  10. EDITORIAL: Focus on Cold and Ultracold Molecules FOCUS ON COLD AND ULTRACOLD MOLECULES

    Science.gov (United States)

    Carr, Lincoln D.; Ye, Jun

    2009-05-01

    Cold and ultracold molecules are the next wave of ultracold physics, giving rise to an exciting array of scientific opportunities, including many body physics for novel quantum phase transitions, new states of matter, and quantum information processing. Precision tests of fundamental physical laws benefit from the existence of molecular internal structure with exquisite control. The study of novel collision and reaction dynamics will open a new chapter of quantum chemistry. Cold molecules bring together researchers from a variety of fields, including atomic, molecular, and optical physics, chemistry and chemical physics, quantum information science and quantum simulations, condensed matter physics, nuclear physics, and astrophysics, a truly remarkable synergy of scientific explorations. For the past decade there have been steady advances in direct cooling techniques, from buffer-gas cooling to cold molecular beams to electro- and magneto-molecular decelerators. These techniques have allowed a large variety of molecules to be cooled for pioneering studies. Recent amazing advances in experimental techniques combining the ultracold and the ultraprecise have furthermore brought molecules to the point of quantum degeneracy. These latter indirect cooling techniques magnetically associate atoms from a Bose-Einstein condensate and/or a quantum degenerate Fermi gas, transferring at 90% efficiency highly excited Fano-Feshbach molecules, which are on the order of 10 000 Bohr radii in size, to absolute ground state molecules just a few Bohr across. It was this latter advance, together with significant breakthroughs in internal state manipulations, which inspired us to coordinate this focus issue now, and is the reason why we say the next wave of ultracold physics has now arrived. Whether directly or indirectly cooled, heteronuclear polar molecules offer distinct new features in comparison to cold atoms, while sharing all of their advantages (purity, high coherence

  11. Small molecules: the missing link in the central dogma.

    Science.gov (United States)

    Schreiber, Stuart L

    2005-07-01

    Small molecules have critical roles at all levels of biological complexity and yet remain orphans of the central dogma. Chemical biologists, working with small molecules, expand our understanding of these central elements of life.

  12. A Simplified Quantum Mechanical Model of Diatomic Molecules

    Science.gov (United States)

    Nielsen, Lars Drud

    1978-01-01

    Introduces a simple one-dimensional model of a diatomic molecule that can explain all the essential features of a real two particle quantum mechanical system and gives quantitative results in fair agreement with those of a hydrogen molecule. (GA)

  13. Nanodevices for generating power from molecules and batteryless sensing

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yinmin; Wang, Xianying; Hamza, Alex V.

    2017-01-03

    A nanoconverter or nanosensor is disclosed capable of directly generating electricity through physisorption interactions with molecules that are dipole containing organic species in a molecule interaction zone. High surface-to-volume ratio semiconductor nanowires or nanotubes (such as ZnO, silicon, carbon, etc.) are grown either aligned or randomly-aligned on a substrate. Epoxy or other nonconductive polymers are used to seal portions of the nanowires or nanotubes to create molecule noninteraction zones. By correlating certain molecule species to voltages generated, a nanosensor may quickly identify which species is detected. Nanoconverters in a series parallel arrangement may be constructed in planar, stacked, or rolled arrays to supply power to nano- and micro-devices without use of external batteries. In some cases breath, from human or other life forms, contain sufficient molecules to power a nanoconverter. A membrane permeable to certain molecules around the molecule interaction zone increases specific molecule nanosensor selectivity response.

  14. A single molecule switch based on two Pd nanocrystals linked

    Indian Academy of Sciences (India)

    Conducting molecule; nanocrystals; scanning tunneling microscopy; negative differential resistance. Abstract. Tunneling spectroscopy measurements have been carried out on a single molecule device formed by two Pd ... Current Issue : Vol.

  15. Magnetic trapping of NH molecules with 20 s lifetimes

    Energy Technology Data Exchange (ETDEWEB)

    Tsikata, E; Campbell, W C; Hummon, M T; Lu, H-I; Doyle, J M, E-mail: tsikata@fas.harvard.ed [Department of Physics, Harvard University, Cambridge, MA (United States)

    2010-06-15

    Buffer gas cooling is used to trap NH molecules with 1/e lifetimes exceeding 20 s. Helium vapor generated by laser desorption of a helium film is employed to thermalize 10{sup 5} molecules at a temperature of 500 mK in a 3.9 T magnetic trap. Long molecule trapping times are attained through rapid pumpout of residual buffer gas. Molecules experience a helium background gas density below 1x10{sup 12} cm{sup -3}.

  16. Recent advances in developing small molecules targeting RNA.

    Science.gov (United States)

    Guan, Lirui; Disney, Matthew D

    2012-01-20

    RNAs are underexploited targets for small molecule drugs or chemical probes of function. This may be due, in part, to a fundamental lack of understanding of the types of small molecules that bind RNA specifically and the types of RNA motifs that specifically bind small molecules. In this review, we describe recent advances in the development and design of small molecules that bind to RNA and modulate function that aim to fill this void.

  17. Nonempirical calculations of the LiBO molecule

    International Nuclear Information System (INIS)

    Nemukhin, A.V.; Stepanov, N.F.

    1987-01-01

    Problems of nonempirical calculations of molecule energies, related to the use of limited basis AO set and configurations were considered taking the LiBO molecule as an example. The version of optimizing parameters of basis functions of the base of the concept of ''atoms in molecules'' was suggested. It is shown that correct description of the potential surface of LiBO molecule is impossible without consideration of electron correlation; main contributions to correlation corrections were distinguished

  18. Electrode redox reactions with polarizable molecules

    Science.gov (United States)

    Matyushov, Dmitry V.

    2018-04-01

    A theory of redox reactions involving electron transfer between a metal electrode and a polarizable molecule in solution is formulated. Both the existence of molecular polarizability and its ability to change due to electron transfer distinguish this problem from classical theories of interfacial electrochemistry. When the polarizability is different between the oxidized and reduced states, the statistics of thermal fluctuations driving the reactant over the activation barrier becomes non-Gaussian. The problem of electron transfer is formulated as crossing of two non-parabolic free energy surfaces. An analytical solution for these free energy surfaces is provided and the activation barrier of electrode electron transfer is given in terms of two reorganization energies corresponding to the oxidized and reduced states of the molecule in solution. The new non-Gaussian theory is, therefore, based on two theory parameters in contrast to one-parameter Marcus formulation for electrode reactions. The theory, which is consistent with the Nernst equation, predicts asymmetry between the cathodic and anodic branches of the electrode current. They show different slopes at small electrode overpotentials and become curved at larger overpotentials. However, the curvature of the Tafel plot is reduced compared to the Marcus-Hush model and approaches the empirical Butler-Volmer form with different transfer coefficients for the anodic and cathodic currents.

  19. Quantum Monte Carlo for vibrating molecules

    International Nuclear Information System (INIS)

    Brown, W.R.; Lawrence Berkeley National Lab., CA

    1996-08-01

    Quantum Monte Carlo (QMC) has successfully computed the total electronic energies of atoms and molecules. The main goal of this work is to use correlation function quantum Monte Carlo (CFQMC) to compute the vibrational state energies of molecules given a potential energy surface (PES). In CFQMC, an ensemble of random walkers simulate the diffusion and branching processes of the imaginary-time time dependent Schroedinger equation in order to evaluate the matrix elements. The program QMCVIB was written to perform multi-state VMC and CFQMC calculations and employed for several calculations of the H 2 O and C 3 vibrational states, using 7 PES's, 3 trial wavefunction forms, two methods of non-linear basis function parameter optimization, and on both serial and parallel computers. In order to construct accurate trial wavefunctions different wavefunctions forms were required for H 2 O and C 3 . In order to construct accurate trial wavefunctions for C 3 , the non-linear parameters were optimized with respect to the sum of the energies of several low-lying vibrational states. In order to stabilize the statistical error estimates for C 3 the Monte Carlo data was collected into blocks. Accurate vibrational state energies were computed using both serial and parallel QMCVIB programs. Comparison of vibrational state energies computed from the three C 3 PES's suggested that a non-linear equilibrium geometry PES is the most accurate and that discrete potential representations may be used to conveniently determine vibrational state energies

  20. Electroluminescence from completely horizontally oriented dye molecules

    Energy Technology Data Exchange (ETDEWEB)

    Komino, Takeshi [Education Center for Global Leaders in Molecular System for Devices, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Center for Organic Photonics and Electronics Research, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Japan Science and Technology Agency, ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Sagara, Yuta [Center for Organic Photonics and Electronics Research, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Tanaka, Hiroyuki [Center for Organic Photonics and Electronics Research, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Department of Chemistry, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8601 (Japan); Oki, Yuji [Japan Science and Technology Agency, ERATO, Adachi Molecular Exciton Engineering Project, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Department of Electronics, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Nakamura, Nozomi [Center for Organic Photonics and Electronics Research, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); International Institute for Carbon Neutral Energy Research (WPI-I2CNER), Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Fujimoto, Hiroshi [Center for Organic Photonics and Electronics Research, Kyushu University, 744 Motooka, Nishi, Fukuoka 819-0395 (Japan); Fukuoka i" 3-Center for Organic Photonics and Electronics Research (i3-OPERA), Fukuoka 819-0388 (Japan); and others

    2016-06-13

    A complete horizontal molecular orientation of a linear-shaped thermally activated delayed fluorescent guest emitter 2,6-bis(4-(10Hphenoxazin-10-yl)phenyl)benzo[1,2-d:5,4-d′] bis(oxazole) (cis-BOX2) was obtained in a glassy host matrix by vapor deposition. The orientational order of cis-BOX2 depended on the combination of deposition temperature and the type of host matrix. Complete horizontal orientation was obtained when a thin film with cis-BOX2 doped in a 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) host matrix was fabricated at 200 K. The ultimate orientation of guest molecules originates from not only the kinetic relaxation but also the kinetic stability of the deposited guest molecules on the film surface during film growth. Utilizing the ultimate orientation, a highly efficient organic light-emitting diode with the external quantum efficiency of 33.4 ± 2.0% was realized. The thermal stability of the horizontal orientation of cis-BOX2 was governed by the glass transition temperature (T{sub g}) of the CBP host matrix; the horizontal orientation was stable unless the film was annealed above T{sub g}.

  1. Half collision resonance phenomena in molecules

    International Nuclear Information System (INIS)

    Maximo Garcia-Sucre; Raseev, G.; Ross, S.C.

    1991-01-01

    The Escuela Latinoamericana de Fisica (ELAF) is a series of meeting s that for 28 years has played an important role in research-level teaching of physics in Latin America. This book contains the proceedings of ELAF 90 which was held at the Instituto Venezolano de Investigaciones Cientificas (IVIC) in Caracas, Venezuela from July 23 to August 3, 1990, as part of the commemoration of the 30th anniversary of IVIC. In contrast to previous ELAF's that were of general scope, ELAF 90 centered on a particular subject matter: '' Half Collisional Resonance Phenomena in Molecules, Experimental and Theoretical Approaches. ''The term ''Half Collision'' refers to the fragmentation of a molecular system following is excitation by light. The lack of an incident fragmentation of a molecular system following is excitation by light. The lack of an incident particle (other than the photon) in the fragmentation process is what leads to the term. The purpose of this volume is to present current results in the experimental and theoretical study of half collisions and also to include pedagogical papers at an introductory or intermediate level. The contributions are grouped into several sections; light sources; ionization; dissociation-experimental; dissociation-theory; competition between ionization and dissociation; and particle-molecule collisions

  2. Quantum Effects in Molecule-Based Nanomagnets

    Science.gov (United States)

    Hill, Stephen

    2005-11-01

    Research into molecule-based-magnets has made immense strides in recent years, with the discoveries of all organic molecular magnets, room temperature 3D ordered permanent magnets, and single-molecule magnets (SMMs), the latter exhibiting a host of spectacular quantum phenomena; for a review, see ref. [1]. SMMs represent a molecular approach to nanoscale and sub-nanoscale magnetic particles. They offer all of the advantages of molecular chemistry as well as displaying the superparamagnetic properties of mesoscale magnetic particles of much larger dimensions. They also straddle the interface between classical and quantum behavior; for example, they exhibit quantum tunneling of their magnetization. I will give a general introduction to this area of research, followed by an overview of recent results obtained using high-frequency (40-800 GHz) electron paramagnetic resonance techniques developed at the University of Florida. These results include: an elucidation of the role of molecular symmetry in the magnetic quantum tunneling phenomenon [2]; and the observation of quantum entanglement between pairs of nanomagnets within a supramolecular dimer [3]. 1. D. Gatteschi and R. Sessoli, Angew. Chem. 42, 268 (2003). 2. E. del Barco et al., J. Low Temp. Phys. 140, 119-174 (2005). 3. S. Hill et al., Science 302, 1015 (2003).

  3. Triton - Stratospheric molecules and organic sediments

    Science.gov (United States)

    Thompson, W. Reid; Singh, Sushil K.; Khare, B. N.; Sagan, Carl

    1989-01-01

    Continuous-flow plasma discharge techniques show production rates of hydrocarbons and nitriles in N2 + CH4 atmospheres appropriate to the stratosphere of Titan, and indicate that a simple eddy diffusion model together with the observed electron flux quantitatively matches the Voyager IRIS observations for all the hydrocarbons, except for the simplest ones. Charged particle chemistry is very important in Triton's stratosphere. In the more CH4-rich case of Titan, many hydrocarbons and nitriles are produced in high yield. If N2 is present, the CH4 fraction is low, but hydrocarbons and nitriles are produced in fair yield, abundances of HCN and C2H2 in Triton's stratosphere exceed 10 to the 19th molecules/sq cm per sec, and NCCN, C3H4, and other species are predicted to be present. These molecules may be detected by IRIS if the stratosphere is as warm as expected. Both organic haze and condensed gases will provide a substantial UV and visible opacity in Triton's atmosphere.

  4. Small molecule antagonists of integrin receptors.

    Science.gov (United States)

    Perdih, A; Dolenc, M Sollner

    2010-01-01

    The complex and widespread family of integrin receptors is involved in numerous physiological processes, such as tissue remodeling, angiogenesis, development of the immune response and homeostasis. In addition, their key role has been elucidated in important pathological disorders such as cancer, cardiovascular diseases, osteoporosis, autoimmune and inflammatory diseases and in the pathogenesis of infectious diseases, making them highly important targets for modern drug design campaigns. In this review we seek to present a concise overview of the small molecule antagonists of this diverse and highly complex receptor family. Integrin antagonists are classified according to the targeted integrin receptor and are discussed in four sections. First we present the fibrinogen alpha(IIb)beta3 and the vitronectin alpha (V)beta(3) receptor antagonists. The remaining selective integrin antagonists are examined in the third section. The final section is dedicated to molecules with dual or multiple integrin activity. In addition, the use of antibodies and peptidomimetic approaches to modulate the integrin receptors are discussed, as well providing the reader with an overall appreciation of the field.

  5. Proteinaceous molecules mediating Bifidobacterium-host interactions

    Directory of Open Access Journals (Sweden)

    Lorena Ruiz

    2016-08-01

    Full Text Available Bifidobacteria are commensal microoganisms found in the gastrointestinal tract.Several strains have been attributed beneficial traits at local and systemic levels, through pathogen exclusion or immune modulation, among other benefits. This has promoted a growing industrial and scientific interest in bifidobacteria as probiotic supplements. However, the molecular mechanisms mediating this cross-talk with the human host remain unknown. High-throughput technologies, from functional genomics to transcriptomics, proteomics and interactomics coupled to the development of both in vitro and in vivo models to study the dynamics of the intestinal microbiota and their effects on host cells, have eased the identification of key molecules in these interactions. Numerous secreted or surface-associated proteins or peptides have been identified as potential mediators of bifidobacteria-host interactions and molecular cross-talk, directly participating in sensing environmental factors, promoting intestinal colonization or mediating a dialogue with mucosa-associated immune cells. On the other hand, bifidobacteria induce the production of proteins in the intestine, by epithelial or immune cells, and other gut bacteria, which are key elements in orchestrating interactions among bifidobacteria, gut microbiota and host cells. This review aims to give a comprehensive overview on proteinaceous molecules described and characterized to date, as mediators of the dynamic interplay between bifidobacteria and the human host, providing a framework to identify knowledge gaps and future research needs.

  6. Magnetization reversal in single molecule magnets

    Science.gov (United States)

    Bokacheva, Louisa

    2002-09-01

    I have studied the magnetization reversal in single molecule magnets (SMMs). SMMs are Van der Waals crystals, consisting of identical molecules containing transition metal ions, with high spin and large uniaxial magnetic anisotropy. They can be considered as ensembles of identical, iso-oriented nanomagnets. At high temperature, these materials behave as superparamagnets and their magnetization reversal occurs by thermal activation. At low temperature they become blocked, and their magnetic relaxation occurs via thermally assisted tunneling or pure quantum tunneling through the anisotropy barrier. We have conducted detailed experimental studies of the magnetization reversal in SMM material Mn12-acetate (Mn12) with S = 10. Low temperature measurements were conducted using micro-Hall effect magnetometry. We performed hysteresis and relaxation studies as a function of temperature, transverse field, and magnetization state of the sample. We identified magnetic sublevels that dominate the tunneling at a given field, temperature and magnetization. We observed a crossover between thermally assisted and pure quantum tunneling. The form of this crossover depends on the magnitude and direction of the applied field. This crossover is abrupt (first-order) and occurs in a narrow temperature interval (tunneling mechanisms in Mn12.

  7. More loosely bound hadron molecules at CDF?

    CERN Document Server

    Bignamini, C; Piccinini, F; Polosa, A D; Riquer, V; Sabelli, C

    2010-01-01

    In a recent paper we have proposed a method to estimate the prompt production cross section of X(3872) at the Tevatron assuming that this particle is a loosely bound molecule of a D and a D*bar meson. Under this hypothesis we find that it is impossible to explain the high prompt production cross section found by CDF at sigma(X(3872)) \\sim 30-70 nb as our theoretical prediction is about 300 times smaller than the measured one. Following our work, Artoisenet and Braaten, have suggested that final state interactions in the DD*bar system might be so strong to push the result we obtained for the cross section up to the experimental value. Relying on their conclusions we show that the production of another very narrow loosely bound molecule, the X_s=D_s D_s*bar, could be similarly enhanced. X_s should then be detectable at CDF with a mass of 4080 MeV and a prompt production cross section of sigma(X_s) \\sim 1-3 nb.

  8. Filovirus tropism: Cellular molecules for viral entry

    Directory of Open Access Journals (Sweden)

    Ayato eTakada

    2012-02-01

    Full Text Available In human and nonhuman primates, filoviruses (Ebola and Marburg viruses cause severe hemorrhagic fever.Recently, other animals such as pigs and some species of fruit bats have also been shown to be susceptible to these viruses. While having a preference for some cell types such as hepatocytes, endothelial cells, dendritic cells, monocytes, and macrophages, filoviruses are known to be pantropic in infection of primates. The envelope glycoprotein (GP is responsible for both receptor binding and fusion of the virus envelope with the host cell membrane. It has been demonstrated that filovirus GP interacts with multiple molecules for entry into host cells, whereas none of the cellular molecules so far identified as a receptor/coreceptor fully explains filovirus tissue tropism and host range. Available data suggest that the mucin-like region (MLR on GP plays an important role in attachment to the preferred target cells, whose infection is likely involved in filovirus pathogenesis, whereas the MLR is not essential for the fundamental function of the GP in viral entry into cells in vitro. Further studies elucidating the mechanisms of cellular entry of filoviruses may shed light on the development of strategies for prophylaxis and treatment of Ebola and Marburg hemorrhagic fevers.

  9. Transport mirages in single-molecule devices

    Science.gov (United States)

    Gaudenzi, R.; Misiorny, M.; Burzurí, E.; Wegewijs, M. R.; van der Zant, H. S. J.

    2017-03-01

    Molecular systems can exhibit a complex, chemically tailorable inner structure which allows for targeting of specific mechanical, electronic, and optical properties. At the single-molecule level, two major complementary ways to explore these properties are molecular quantum-dot structures and scanning probes. This article outlines comprehensive principles of electron-transport spectroscopy relevant to both these approaches and presents a new, high-resolution experiment on a high-spin single-molecule junction exemplifying these principles. Such spectroscopy plays a key role in further advancing our understanding of molecular and atomic systems, in particular, the relaxation of their spin. In this joint experimental and theoretical analysis, particular focus is put on the crossover between the resonant regime [single-electron tunneling] and the off-resonant regime [inelastic electron (co)tunneling spectroscopy (IETS)]. We show that the interplay of these two processes leads to unexpected mirages of resonances not captured by either of the two pictures alone. Although this turns out to be important in a large fraction of the possible regimes of level positions and bias voltages, it has been given little attention in molecular transport studies. Combined with nonequilibrium IETS—four-electron pump-probe excitations—these mirages provide crucial information on the relaxation of spin excitations. Our encompassing physical picture is supported by a master-equation approach that goes beyond weak coupling. The present work encourages the development of a broader connection between the fields of molecular quantum-dot and scanning probe spectroscopy.

  10. Carbon Monoxide: An Essential Signalling Molecule

    Science.gov (United States)

    Mann, Brian E.

    Carbon monoxide (CO), like nitric oxide (NO), is an essential signalling molecule in humans. It is active in the cardiovascular system as a vasodilator. In addition, CO possesses anti-inflammatory, anti-apoptotic and anti-proliferative properties and protects tissues from hypoxia and reperfusion injury. Some of its applications in animal models include suppression of organ graft rejection and safeguarding the heart during reperfusion after cardiopulmonary bypass surgery. CO also suppresses arteriosclerotic lesions following angioplasty, reverses established pulmonary hypertension and mitigates the development of post-operative ileus in the murine small intestine and the development of cerebral malaria in mice as well as graft-induced intimal hyperplasia in pigs. There have been several clinical trials using air-CO mixtures for the treatment of lung-, heart-, kidney- and abdominal-related diseases. This review examines the research involving the development of classes of compounds (with particular emphasis on metal carbonyls) that release CO, which could be used in clinically relevant conditions. The review is drawn not only from published papers in the chemical literature but also from the extensive biological literature and patents on CO-releasing molecules (CO-RMs).

  11. Radical inactivation of a biological sulphydryl molecule

    International Nuclear Information System (INIS)

    Lin, W.S.; Lal, M.; Gaucher, G.M.; Armstrong, D.A.

    1977-01-01

    Reactive species produced from the free radical-induced chain oxidation of low molecular weight sulphydryl-containing molecules in aerated solutions deactivate the sulphydryl-containing enzyme papain, forming both reparable mixed disulphides and non-reparable products. This inactivation is highly efficient for penicillamine and glutathione, but almost negligible with cysteine, which is a protector of papain for [cysteine] / [papain] >= 5 under all conditions used. In the case of glutathione, superoxide dismutase caused only a small reduction in the inactivation and peroxide yields were small, implying that the deactivating species are not .O 2 - but RSOO. radicals or products from them. For penicillamine, however, dimutase was highly effective and the peroxide yields were relatively large, demonstrating that .O 2 - or a radical with similar capabilities for forming H 2 O 2 and being deactivated by dismutase was involved. Although in the presence of dismutase penicillamine is a better protector of non-reparable papain inactivation than glutathione, it suffers from a deficiency in that the papain-penicillamine mixed disulphide, which is always formed, cannot be repaired by spontaneous reaction with RSH molecules. (author)

  12. Atomic-Scale Control of Electron Transport through Single Molecules

    DEFF Research Database (Denmark)

    Wang, Y. F.; Kroger, J.; Berndt, R.

    2010-01-01

    Tin-phthalocyanine molecules adsorbed on Ag(111) were contacted with the tip of a cryogenic scanning tunneling microscope. Orders-of-magnitude variations of the single-molecule junction conductance were achieved by controllably dehydrogenating the molecule and by modifying the atomic structure...

  13. Molecular electronics with single molecules in solid-state devices

    DEFF Research Database (Denmark)

    Moth-Poulsen, Kasper; Bjørnholm, Thomas

    2009-01-01

    The ultimate aim of molecular electronics is to understand and master single-molecule devices. Based on the latest results on electron transport in single molecules in solid-state devices, we focus here on new insights into the influence of metal electrodes on the energy spectrum of the molecule...

  14. Optical probing of single fluorescent molecules and proteins

    NARCIS (Netherlands)

    Garcia Parajo, M.F.; Veerman, J.A.; Bouwhuis, R.; Bouwhuis, Rudo; van Hulst, N.F.; Vallée, R.A.L.

    2001-01-01

    Single-molecule detection and analysis of organic fluorescent molecules and proteins are presented, with emphasis o­n the underlying principles methodology and the application of single-molecule analysis at room temperature. This Minireview is mainly focused o­n the application of confocal and

  15. Bacterial Vaginosis Bacterial and Epithelial Cell Adhesion Molecules

    Directory of Open Access Journals (Sweden)

    Şayeste Demirezen

    2016-05-01

    molecules. The most important adhesion molecules of epithelium are cadherins, fibronectins, Toll like receptors and carbohydrates. In bacteria, pilis, lypopolysaccaharide and biofilm have primary importance. In this review, the adhesion molecules are discussed in detail and their roles in formation of clue cell are clarified.

  16. A brief introduction to single-molecule fluorescence methods

    NARCIS (Netherlands)

    Wildenberg, S.M.J.L.; Prevo, B.; Peterman, E.J.G.; Peterman, EJG; Wuite, GJL

    2011-01-01

    One of the more popular single-molecule approaches in biological science is single-molecule fluorescence microscopy, which is the subject of the following section of this volume. Fluorescence methods provide the sensitivity required to study biology on the single-molecule level, but they also allow

  17. A brief introduction to single-molecule fluorescence methods

    NARCIS (Netherlands)

    van den Wildenberg, Siet M.J.L.; Prevo, Bram; Peterman, Erwin J.G.

    2018-01-01

    One of the more popular single-molecule approaches in biological science is single-molecule fluorescence microscopy, which will be the subject of the following section of this volume. Fluorescence methods provide the sensitivity required to study biology on the single-molecule level, but they also

  18. selective excitation of vibrational modes of polyatomic molecule

    Indian Academy of Sciences (India)

    Abstract. Mode-selective dynamics of triatomic molecule in the electronic ground state under continuous wave laser pulse is investigated for the discrete vibrational bound states. A non-perturbative approach has been used to analyse the vibrational couplings and dynamics of the molecule. Keywords. Polyatomic molecule ...

  19. Filming the Birth of Molecules and Accompanying Solvent Rearrangement

    DEFF Research Database (Denmark)

    Lee, Jae Hyuk; Wulff, Michael; Bratos, Savo

    2013-01-01

    Molecules are often born with high energy and large-amplitude vibrations. In solution, a newly formed molecule cools down by transferring energy to the surrounding solvent molecules. The progression of the molecular and solute−solvent cage structure during this fundamental process has been elusiv...

  20. Entangled exciton states in quantum dot molecules

    Science.gov (United States)

    Bayer, Manfred

    2002-03-01

    Currently there is strong interest in quantum information processing(See, for example, The Physics of Quantum Information, eds. D. Bouwmeester, A. Ekert and A. Zeilinger (Springer, Berlin, 2000).) in a solid state environment. Many approaches mimic atomic physics concepts in which semiconductor quantum dots are implemented as artificial atoms. An essential building block of a quantum processor is a gate which entangles the states of two quantum bits. Recently a pair of vertically aligned quantum dots has been suggested as optically driven quantum gate(P. Hawrylak, S. Fafard, and Z. R. Wasilewski, Cond. Matter News 7, 16 (1999).)(M. Bayer, P. Hawrylak, K. Hinzer, S. Fafard, M. Korkusinski, Z.R. Wasilewski, O. Stern, and A. Forchel, Science 291, 451 (2001).): The quantum bits are individual carriers either on dot zero or dot one. The different dot indices play the same role as a "spin", therefore we call them "isospin". Quantum mechanical tunneling between the dots rotates the isospin and leads to superposition of these states. The quantum gate is built when two different particles, an electron and a hole, are created optically. The two particles form entangled isospin states. Here we present spectrocsopic studies of single self-assembled InAs/GaAs quantum dot molecules that support the feasibility of this proposal. The evolution of the excitonic recombination spectrum with varying separation between the dots allows us to demonstrate coherent tunneling of carriers across the separating barrier and the formation of entangled exciton states: Due to the coupling between the dots the exciton states show a splitting that increases with decreasing barrier width. For barrier widths below 5 nm it exceeds the thermal energy at room temperature. For a given barrier width, we find only small variations of the tunneling induced splitting demonstrating a good homogeneity within a molecule ensemble. The entanglement may be controlled by application of electromagnetic field. For

  1. Excitonic Coupling in Linear and Trefoil Trimer Perylenediimide Molecules Probed by Single-Molecule Spectroscopy

    KAUST Repository

    Yoo, Hyejin

    2012-10-25

    Perylenediimide (PDI) molecules are promising building blocks for photophysical studies of electronic interactions within multichromophore arrays. Such PDI arrays are important materials for fabrication of molecular nanodevices such as organic light-emitting diodes, organic semiconductors, and biosensors because of their high photostability, chemical and physical inertness, electron affinity, and high tinctorial strength over the entire visible spectrum. In this work, PDIs have been organized into linear (L3) and trefoil (T3) trimer molecules and investigated by single-molecule fluorescence microscopy to probe the relationship between molecular structures and interchromophoric electronic interactions. We found a broad distribution of coupling strengths in both L3 and T3 and hence strong/weak coupling between PDI units by monitoring spectral peak shifts in single-molecule fluorescence spectra upon sequential photobleaching of each constituent chromophore. In addition, we used a wide-field defocused imaging technique to resolve heterogeneities in molecular structures of L3 and T3 embedded in a PMMA polymer matrix. A systematic comparison between the two sets of experimental results allowed us to infer the correlation between intermolecular interactions and molecular structures. Our results show control of the PDI intermolecular interactions using suitable multichromophoric structures. © 2012 American Chemical Society.

  2. Small Molecule Agonists of Cell Adhesion Molecule L1 Mimic L1 Functions In Vivo.

    Science.gov (United States)

    Kataria, Hardeep; Lutz, David; Chaudhary, Harshita; Schachner, Melitta; Loers, Gabriele

    2016-09-01

    Lack of permissive mechanisms and abundance of inhibitory molecules in the lesioned central nervous system of adult mammals contribute to the failure of functional recovery after injury, leading to severe disabilities in motor functions and pain. Peripheral nerve injury impairs motor, sensory, and autonomic functions, particularly in cases where nerve gaps are large and chronic nerve injury ensues. Previous studies have indicated that the neural cell adhesion molecule L1 constitutes a viable target to promote regeneration after acute injury. We screened libraries of known drugs for small molecule agonists of L1 and evaluated the effect of hit compounds in cell-based assays in vitro and in mice after femoral nerve and spinal cord injuries in vivo. We identified eight small molecule L1 agonists and showed in cell-based assays that they stimulate neuronal survival, neuronal migration, and neurite outgrowth and enhance Schwann cell proliferation and migration and myelination of neurons in an L1-dependent manner. In a femoral nerve injury mouse model, enhanced functional regeneration and remyelination after application of the L1 agonists were observed. In a spinal cord injury mouse model, L1 agonists improved recovery of motor functions, being paralleled by enhanced remyelination, neuronal survival, and monoaminergic innervation, reduced astrogliosis, and activation of microglia. Together, these findings suggest that application of small organic compounds that bind to L1 and stimulate the beneficial homophilic L1 functions may prove to be a valuable addition to treatments of nervous system injuries.

  3. Single-Molecule Photocurrent at a Metal-Molecule-Semiconductor Junction.

    Science.gov (United States)

    Vezzoli, Andrea; Brooke, Richard J; Higgins, Simon J; Schwarzacher, Walther; Nichols, Richard J

    2017-11-08

    We demonstrate here a new concept for a metal-molecule-semiconductor nanodevice employing Au and GaAs contacts that acts as a photodiode. Current-voltage traces for such junctions are recorded using a STM, and the "blinking" or "I(t)" method is used to record electrical behavior at the single-molecule level in the dark and under illumination, with both low and highly doped GaAs samples and with two different types of molecular bridge: nonconjugated pentanedithiol and the more conjugated 1,4-phenylene(dimethanethiol). Junctions with highly doped GaAs show poor rectification in the dark and a low photocurrent, while junctions with low doped GaAs show particularly high rectification ratios in the dark (>10 3 for a 1.5 V bias potential) and a high photocurrent in reverse bias. In low doped GaAs, the greater thickness of the depletion layer not only reduces the reverse bias leakage current, but also increases the volume that contributes to the photocurrent, an effect amplified by the point contact geometry of the junction. Furthermore, since photogenerated holes tunnel to the metal electrode assisted by the HOMO of the molecular bridge, the choice of the latter has a strong influence on both the steady state and transient metal-molecule-semiconductor photodiode response. The control of junction current via photogenerated charge carriers adds new functionality to single-molecule nanodevices.

  4. Epithelial cell adhesion molecule - More than a carcinoma marker and adhesion molecule

    NARCIS (Netherlands)

    Trzpis, Monika; McLaughlin, Pamela M. J.; de Leij, Lou M. F. H.; Harmsen, Martin C.

    The epithetial cell adhesion molecule (EpCAM, CD326) is a glycoprotein of similar to 40 kd that was originally identified as a marker for carcinoma, attributable to its high expression on rapidly proliferating tumors of epithelial origin. Normal epithelia express EpCAM at a variable but generally

  5. Engineering and control of cold molecules. Making manipulating and exploiting ultra-cold polar molecules

    International Nuclear Information System (INIS)

    Bigelow, N.P.; Haimberger, C.; Kleinert, J.; Tscherneck, M.; Holmes, M.E.

    2005-01-01

    In the last 12 months several groups have demonstrated the use of photo association to create cold heteronuclear (polar) molecules. We report on the formation of translationally cold NaCs molecules starting from a laser-cooled atomic vapor of Na and Cs atoms. Colliding atoms are transferred into bound molecular states in a two-step photoactivated process. We find a translational temperature of T ≅ 260 mK. To increase the density and number of trapped atoms, dark-spot techniques are used on the MOT and a Zeeman slowed sodium beam is used to load the sodium atoms into the trap. Spectroscopy of these molecules is underway using time-of-flight ion detection and trap-loss. Initial REMPI measurements indicate that both singlet and triplet states are being populated by the spontaneous-decay driven process. We measure a rate constant for molecule formation of K NaCs = 7.43 · 10 15 cm 3 s -1 . (author)

  6. Excitonic Coupling in Linear and Trefoil Trimer Perylenediimide Molecules Probed by Single-Molecule Spectroscopy

    KAUST Repository

    Yoo, Hyejin; Furumaki, Shu; Yang, Jaesung; Lee, Ji-Eun; Chung, Heejae; Oba, Tatsuya; Kobayashi, Hiroyuki; Rybtchinski, Boris; Wilson, Thea M.; Wasielewski, Michael R.; Vacha, Martin; Kim, Dongho

    2012-01-01

    Perylenediimide (PDI) molecules are promising building blocks for photophysical studies of electronic interactions within multichromophore arrays. Such PDI arrays are important materials for fabrication of molecular nanodevices such as organic light-emitting diodes, organic semiconductors, and biosensors because of their high photostability, chemical and physical inertness, electron affinity, and high tinctorial strength over the entire visible spectrum. In this work, PDIs have been organized into linear (L3) and trefoil (T3) trimer molecules and investigated by single-molecule fluorescence microscopy to probe the relationship between molecular structures and interchromophoric electronic interactions. We found a broad distribution of coupling strengths in both L3 and T3 and hence strong/weak coupling between PDI units by monitoring spectral peak shifts in single-molecule fluorescence spectra upon sequential photobleaching of each constituent chromophore. In addition, we used a wide-field defocused imaging technique to resolve heterogeneities in molecular structures of L3 and T3 embedded in a PMMA polymer matrix. A systematic comparison between the two sets of experimental results allowed us to infer the correlation between intermolecular interactions and molecular structures. Our results show control of the PDI intermolecular interactions using suitable multichromophoric structures. © 2012 American Chemical Society.

  7. The instability of molecules in laser field and isotope separation

    International Nuclear Information System (INIS)

    Li, K.

    1981-01-01

    In the present paper the nonlinear differential equation describing the selective decomposition of a molecule as an unimolecular reaction has be deduced from the usual time dependent semi-classical Schroedinger equation. The selective conditions for the instability of a molecule are discussed. The thresholds of the required laser intensities for ICl and HCl diatomic molecules are estimated respectively, where on type of isotope molecules ought to be decomposed for hundred per cent in a laser pulse for different pulse widths. And possibly selective decomposition of the molecule without permanent dipole moment by Raman process is also discussed briefly. (orig.)

  8. Analysis of experimental positron-molecule binding energies

    International Nuclear Information System (INIS)

    Danielson, J R; Surko, C M; Young, J A

    2010-01-01

    Experiments show that positron annihilation on molecules frequently occurs via capture into vibrational Feshbach resonances. In these cases, the downshifts in the annihilation spectra from the vibrational mode spectra provide measures of the positron-molecule binding energies. An analysis of these binding energy data is presented in terms of the molecular dipole polarizability, the permanent dipole moment, and the number of π bonds in aromatic molecules. The results of this analysis are in reasonably good agreement with other information about positron-molecule bound states. Predictions for other targets and promising candidate molecules for further investigation are discussed.

  9. Slow neutron scattering by water molecules

    Energy Technology Data Exchange (ETDEWEB)

    Stancic, V [Boris Kidric Institute of Nuclear Sciences Vinca, Beograd (Yugoslavia)

    1970-07-01

    In this work some new, preliminary formulae for slow neutron scattering cross section calculation by heavy and light water molecules have been done. The idea was to find, from the sum which exists in well known Nelkin model, other cross sections in a more simple analytical form, so that next approximations may be possible. In order to sum a series it was starting from Euler-Mclaurin formula. Some new summation formulae have been derived there, and defined in two theorems. Extensive calculations, especially during the evaluation of residues, have been made at the CDC 3600 computer. validation of derived formulae was done by comparison with the BNL-325 results. Good agreement is shown. (author)

  10. The calculation of thermodynamic properties of molecules

    DEFF Research Database (Denmark)

    van Speybroeck, Veronique; Gani, Rafiqul; Meier, Robert Johan

    2010-01-01

    Thermodynamic data are key in the understanding and design of chemical processes. Next to the experimental evaluation of such data, computational methods are valuable and sometimes indispensable tools in obtaining heats of formation and Gibbs free energies. The major toolboxes to obtain such quan......Thermodynamic data are key in the understanding and design of chemical processes. Next to the experimental evaluation of such data, computational methods are valuable and sometimes indispensable tools in obtaining heats of formation and Gibbs free energies. The major toolboxes to obtain...... molecules the combination of group contribution methods with group additive values that are determined with the best available computational ab initio methods seems to be a viable alternative to obtain thermodynamic properties near chemical accuracy. New developments and full use of existing tools may lead...

  11. Special Issue: “Molecules against Alzheimer”

    Directory of Open Access Journals (Sweden)

    Michael Decker

    2016-12-01

    Full Text Available This Special Issue, entitled “Molecules against Alzheimer”, gathers a number of original articles, short communications, and review articles on recent research efforts toward the development of novel drug candidates, diagnostic agents and therapeutic approaches for Alzheimer’s disease (AD, the most prevalent neurodegenerative disorder and a leading cause of death worldwide. This Special Issue contains many interesting examples describing the design, synthesis, and pharmacological profiling of novel compounds that hit one or several key biological targets, such as cholinesterases, β-amyloid formation or aggregation, monoamine oxidase B, oxidative stress, biometal dyshomeostasis, mitochondrial dysfunction, serotonin and/or melatonin systems, the Wnt/β-catenin pathway, sigma receptors, nicotinamide phosphoribosyltransferase, or nuclear erythroid 2-related factor. The development of novel AD diagnostic agents based on tau protein imaging and the use of lithium or intranasal insulin for the prevention or the symptomatic treatment of AD is also covered in some articles of the Special Issue.

  12. Alkaline pH sensor molecules.

    Science.gov (United States)

    Murayama, Takashi; Maruyama, Ichiro N

    2015-11-01

    Animals can survive only within a narrow pH range. This requires continual monitoring of environmental and body-fluid pH. Although a variety of acidic pH sensor molecules have been reported, alkaline pH sensor function is not well understood. This Review describes neuronal alkaline pH sensors, grouped according to whether they monitor extracellular or intracellular alkaline pH. Extracellular sensors include the receptor-type guanylyl cyclase, the insulin receptor-related receptor, ligand-gated Cl- channels, connexin hemichannels, two-pore-domain K+ channels, and transient receptor potential (TRP) channels. Intracellular sensors include TRP channels and gap junction channels. Identification of molecular mechanisms underlying alkaline pH sensing is crucial for understanding how animals respond to environmental alkaline pH and how body-fluid pH is maintained within a narrow range. © 2015 Wiley Periodicals, Inc.

  13. Theoretical studies of the C4 molecule

    International Nuclear Information System (INIS)

    Ritchie, J.P.; King, H.F.; Young, W.S.

    1985-01-01

    Optimized geometries and relative energies for three states of the C 4 molecule have been obtained from single-reference configuration interaction (SRCI) calculations. At the SRCI level, a rhombic form is calculated to lie 1.1 kcal below the triplet form; consideration of the Davidson correction reduces this difference to 0.4 kcal, while more complete basis sets are expected to increase the difference only by about 0.2 kcal. Consideration of these effects and difference in zero-point energy leads to a final estimated splitting of 1.2 kcal, favoring the rhombus. To aid the determination of the ground state, preliminary estimates of the lowest optical transitions were obtained from SRCI calculations and vibrational frequencies were obtained from SCF calculations. Comparison of the calculated results with experimentally obtained spectra suggest the possibility that both the linear triplet and the rhombus may have already been observed. 19 refs., 4 figs., 4 tabs

  14. Relaxation of the magnetization in magnetic molecules

    Science.gov (United States)

    Carretta, S.; Bianchi, A.; Liviotti, E.; Santini, P.; Amoretti, G.

    2006-04-01

    Several mechanisms characterize the relaxation dynamics in magnetic molecules. We investigate two of them, spin-lattice coupling and incoherent quantum tunneling. The effect of the phonon heat bath is studied by analyzing the exponential time decay of the autocorrelation of the magnetization. We show that in ferromagnetic (Cu6) and antiferromagnetic (Fe6) molecular rings this decay is characterized by a single characteristic time. At very low temperature, relaxation through incoherent quantum tunneling may occur in nanomagnets such as Fe8 or Ni4. The mixing between levels with different values of the total spin (S mixing) greatly influences this mechanism. In particular, we demonstrate that a fourth-order anisotropy term O44, required to interpret experimental electron paramagnetic resonance and relaxation data in Ni4, naturally arises when S mixing is considered in calculations.

  15. Systemic Inflammatory Response and Adhesion Molecules

    Directory of Open Access Journals (Sweden)

    L. V. Molchanova

    2005-01-01

    Full Text Available The lecture presents the materials of foreign studies on the mechanisms responsible for the formation of a systemic inflammatory response syndrome (SIRS. The hypotheses accounting for the occurrence of SIRS in emergencies are described. Adhesion molecules (AM and endothelial dysfunction are apparent to be involved in the inflammatory process, no matter what the causes of SIRS are. The current classification of AM and adhesion cascades with altered blood flow is presented. There are two lines in the studies of AM. One line is to measure the concentration of AM in the plasma of patients with emergencies of various etiology. The other is to study the impact of antiadhesion therapy on the alleviation of the severity of terminal state and its outcome. The studies provide evidence for that an adhesive process is a peculiar prelude to a systemic inflammatory response.

  16. Small Molecule Library Synthesis Using Segmented Flow

    Directory of Open Access Journals (Sweden)

    Christina M. Thompson

    2011-11-01

    Full Text Available Flow chemistry has gained considerable recognition as a simple, efficient, and safe technology for the synthesis of many types of organic and inorganic molecules ranging in scope from large complex natural products to silicon nanoparticles. In this paper we describe a method that adapts flow chemistry to the synthesis of libraries of compounds using a fluorous immiscible solvent as a spacer between reactions. The methodology was validated in the synthesis of two small heterocycle containing libraries. The reactions were performed on a 0.2 mmol scale, enabling tens of milligrams of material to be generated in a single 200 mL reaction plug. The methodology allowed library synthesis in half the time of conventional microwave synthesis while maintaining similar yields. The ability to perform multiple, potentially unrelated reactions in a single run is ideal for making small quantities of many different compounds quickly and efficiently.

  17. Evolutionary game theory: molecules as players.

    Science.gov (United States)

    Bohl, Katrin; Hummert, Sabine; Werner, Sarah; Basanta, David; Deutsch, Andreas; Schuster, Stefan; Theissen, Günter; Schroeter, Anja

    2014-12-01

    In this and an accompanying paper we review the use of game theoretical concepts in cell biology and molecular biology. This review focuses on the subcellular level by considering viruses, genes, and molecules as players. We discuss in which way catalytic RNA can be treated by game theory. Moreover, genes can compete for success in replication and can have different strategies in interactions with other genetic elements. Also transposable elements, or "jumping genes", can act as players because they usually bear different traits or strategies. Viruses compete in the case of co-infecting a host cell. Proteins interact in a game theoretical sense when forming heterodimers. Finally, we describe how the Shapley value can be applied to enzymes in metabolic pathways. We show that game theory can be successfully applied to describe and analyse scenarios at the molecular level resulting in counterintuitive conclusions.

  18. hermal decomposition of irradiated casein molecules

    International Nuclear Information System (INIS)

    Ali, M.A.; Elsayed, A.A.

    1998-01-01

    NON-Isothermal studies were carried out using the derivatograph where thermogravimetry (TG) and differential thermogravimetry (DTG) measurements were used to obtain the activation energies of the first and second reactions for casein (glyco-phospho-protein) decomposition before and after exposure to 1 Gy γ-rays and up to 40 x 1 04 μg Gy fast neutrons. 25C f was used as a source of fast neutrons, associated with γ-rays. 137 Cs source was used as pure γ-source. The activation energies for the first and second reactions for casein decomposition were found to be smaller at 400 μGy than that at lower and higher fast neutron doses. However, no change in activation energies was observed after γ-irradiation. it is concluded from the present study that destruction of casein molecules by low level fast neutron doses may lead to changes of shelf storage period of milk

  19. Small-molecule AT2 receptor agonists

    DEFF Research Database (Denmark)

    Hallberg, Mathias; Sumners, Colin; Steckelings, U Muscha

    2018-01-01

    The discovery of the first selective, small-molecule ATR receptor (AT2R) agonist compound 21 (C21) (8) that is now extensively studied in a large variety of in vitro and in vivo models is described. The sulfonylcarbamate derivative 8, encompassing a phenylthiofen scaffold is the drug-like agonist...... with the highest affinity for the AT2R reported to date (Ki = 0.4 nM). Structure-activity relationships (SAR), regarding different biaryl scaffolds and functional groups attached to these scaffolds and with a particular focus on the impact of various para substituents displacing the methylene imidazole group of 8......, are discussed. Furthermore, the consequences of migration of the methylene imidazole group and presumed structural requirements for ligands that are aimed as AT2R agonists (e.g. 8) or AT2R antagonists (e.g. 9), respectively, are briefly addressed. A summary of the pharmacological actions of C21 (8) is also...

  20. Single molecule magnets from magnetic building blocks

    Science.gov (United States)

    Kroener, W.; Paretzki, A.; Cervetti, C.; Hohloch, S.; Rauschenbach, S.; Kern, K.; Dressel, M.; Bogani, L.; M&üLler, P.

    2013-03-01

    We provide a basic set of magnetic building blocks that can be rationally assembled, similar to magnetic LEGO bricks, in order to create a huge variety of magnetic behavior. Using rare-earth centers and multipyridine ligands, fine-tuning of intra and intermolecular exchange interaction is demonstrated. We have investigated a series of molecules with monomeric, dimeric and trimeric lanthanide centers using SQUID susceptometry and Hall bar magnetometry. A home-made micro-Hall-probe magnetometer was used to measure magnetic hysteresis loops at mK temperatures and fields up to 17 T. All compounds show hysteresis below blocking temperatures of 3 to 4 K. The correlation of the assembly of the building blocks with the magnetic properties will be discussed.

  1. Monitoring Molecules in Neuroscience Then and Now.

    Science.gov (United States)

    Rice, Margaret E

    2017-02-15

    The 16th International Conference on Monitoring Molecules in Neuroscience (MMiN) was held in Gothenburg, Sweden in late spring 2016. This conference originated as a methods meeting focused on in vivo voltammetric techniques and microdialysis. Over time, however, the scope has evolved to include a number of other methods for neurochemical detection that range from single-cell fluorescence in vitro and in vivo in animal models to whole-brain imaging in humans. Overall, MMiN provides a unique forum for introducing new developments in neurochemical detection, as well as for reporting exciting neurobiological insights provided by established and novel methods. This Viewpoint includes a brief history of the meeting, factors that have contributed its evolution, and some highlights of MMiN 2016.

  2. Double differential cross sections of ethane molecule

    Science.gov (United States)

    Kumar, Rajeev

    2018-05-01

    Partial and total double differential cross sections corresponding to various cations C2H6+, C2H4+, C2H5+, C2H3+, C2H2+, CH3+, H+, CH2+, C2H+, H2+, CH+, H3+, C2+ and C+ produced during the direct and dissociative electron ionization of Ethane (C2H6) molecule have been calculated at fixed impinging electron energies 200 and 500eV by using modified Jain-Khare semi empirical approach. The calculation for double differential cross sections is made as a function of energy loss suffered by primary electron and angle of incident. To the best of my knowledge no other data is available for the comparison.

  3. Mechanochemical synthesis of small organic molecules

    Directory of Open Access Journals (Sweden)

    Tapas Kumar Achar

    2017-09-01

    Full Text Available With the growing interest in renewable energy and global warming, it is important to minimize the usage of hazardous chemicals in both academic and industrial research, elimination of waste, and possibly recycle them to obtain better results in greener fashion. The studies under the area of mechanochemistry which cover the grinding chemistry to ball milling, sonication, etc. are certainly of interest to the researchers working on the development of green methodologies. In this review, a collection of examples on recent developments in organic bond formation reactions like carbon–carbon (C–C, carbon–nitrogen (C–N, carbon–oxygen (C–O, carbon–halogen (C–X, etc. is documented. Mechanochemical syntheses of heterocyclic rings, multicomponent reactions and organometallic molecules including their catalytic applications are also highlighted.

  4. Extracellular Matrix Molecules Facilitating Vascular Biointegration

    Directory of Open Access Journals (Sweden)

    Martin K.C. Ng

    2012-08-01

    Full Text Available All vascular implants, including stents, heart valves and graft materials exhibit suboptimal biocompatibility that significantly reduces their clinical efficacy. A range of biomolecules in the subendothelial space have been shown to play critical roles in local regulation of thrombosis, endothelial growth and smooth muscle cell proliferation, making these attractive candidates for modulation of vascular device biointegration. However, classically used biomaterial coatings, such as fibronectin and laminin, modulate only one of these components; enhancing endothelial cell attachment, but also activating platelets and triggering thrombosis. This review examines a subset of extracellular matrix molecules that have demonstrated multi-faceted vascular compatibility and accordingly are promising candidates to improve the biointegration of vascular biomaterials.

  5. Low energy ion-molecule reactions

    Energy Technology Data Exchange (ETDEWEB)

    Farrar, J.M. [Univ. of Rochester, NY (United States)

    1993-12-01

    This project is concerned with elucidating the dynamics of elementary ion-molecule reactions at collision energies near and below 1 eV. From measurements of the angular and energy distributions of the reaction products, one can infer intimathe details about the nature of collisions leading to chemical reaction, the geometries and lifetimes of intermediate complexes that govern the reaction dynamics, and the collision energy dependence of these dynamical features. The author employs crossed-beam low energy mass spectrometry technology developed over the last several years, with the focus of current research on proton transfer and hydrogen atom transfer reactions of te O{sup {minus}} ion with species such as HF, H{sub 2}O, and NH{sub 3}.

  6. Slow neutron scattering by water molecules

    International Nuclear Information System (INIS)

    Stancic, V.

    1970-01-01

    In this work some new, preliminary formulae for slow neutron scattering cross section calculation by heavy and light water molecules have been done. The idea was to find, from the sum which exists in well known Nelkin model, other cross sections in a more simple analytical form, so that next approximations may be possible. In order to sum a series it was starting from Euler-Mclaurin formula. Some new summation formulae have been derived there, and defined in two theorems. Extensive calculations, especially during the evaluation of residues, have been made at the CDC 3600 computer. validation of derived formulae was done by comparison with the BNL-325 results. Good agreement is shown. (author)

  7. Rotational partition functions for linear molecules

    International Nuclear Information System (INIS)

    McDowell, R.S.

    1988-01-01

    An accurate closed-form expression for the rotational partition function of linear polyatomic molecules in 1 summation electronic states is derived, including the effect of nuclear spin (significant at very low temperatures) and of quartic and sextic centrifugal distortion terms (significant at moderate and high temperatures). The proper first-order quantum correction to the classical rigid-rotator partition function is shown to yield Q/sub r/ ≅β -1 exp(β/3), where βequivalenthcB/kT and B is the rotational constant in cm -1 ; for β≥0.2 additional power-series terms in β are necessary. Comparison between the results of this treatment and exact summations are made for HCN and C 2 H 2 at temperatures from 2 to 5000 K, including separate evaluation of the contributions of nuclear spin and centrifugal distortion

  8. Formation of ultracold NaRb Feshbach molecules

    International Nuclear Information System (INIS)

    Wang, Fudong; He, Xiaodong; Li, Xiaoke; Zhu, Bing; Chen, Jun; Wang, Dajun

    2015-01-01

    We report the creation of ultracold bosonic 23 Na 87 Rb Feshbach molecules via magneto-association. By ramping the magnetic field across an interspecies Feshbach resonance (FR), at least 4000 molecules can be produced out of the near degenerate ultracold mixture. Fast loss due to inelastic atom–molecule collisions is observed, which limits the pure molecule number, after residual atoms removal, to 1700. The pure molecule sample can live for 21.8(8) ms in the optical trap, long enough for future molecular spectroscopy studies toward coherently transferring to the singlet ro-vibrational ground state, where these molecules are stable against chemical reaction and have a permanent electric dipole moment of 3.3 Debye. We have also measured the Feshbach molecule’s binding energy near the FR by the oscillating magnetic field method and found these molecules have a large closed-channel fraction. (paper)

  9. Single molecule force spectroscopy: methods and applications in biology

    International Nuclear Information System (INIS)

    Shen Yi; Hu Jun

    2012-01-01

    Single molecule measurements have transformed our view of biomolecules. Owing to the ability of monitoring the activity of individual molecules, we now see them as uniquely structured, fluctuating molecules that stochastically transition between frequently many substrates, as two molecules do not follow precisely the same trajectory. Indeed, it is this discovery of critical yet short-lived substrates that were often missed in ensemble measurements that has perhaps contributed most to the better understanding of biomolecular functioning resulting from single molecule experiments. In this paper, we give a review on the three major techniques of single molecule force spectroscopy, and their applications especially in biology. The single molecular study of biotin-streptavidin interactions is introduced as a successful example. The problems and prospects of the single molecule force spectroscopy are discussed, too. (authors)

  10. New Phase in the System Uranium-Molybdenum-Silicon; Nouvelle phase dans le systeme uranium-molybdene-silicium; Novaya faza v sisteme uran-molibden'-kremnij; Una fase nueva en el sistema uranio-molibdeno-silicio

    Energy Technology Data Exchange (ETDEWEB)

    Sikirica, M.; Ban, Z. [Rudjer Bokovic Institute, Zagreb, Yugoslavia (Croatia)

    1963-11-15

    During the investigation of the ternary system uranium-molybdenum-silicon, a new phase with the composition U{sub 4}Mo{sub 5}-Si{sub 3} was formed. Structure determination exclusively based on the powder data showed that the particular phase belongs to the hexagonal system. Space group P6/mmc or one of the sub-groups is indicated. Unit cell dimensions were found to be a = 5.37{sub 0}A, c = 8 . 58{sub 2}A. A comparison of calculated and observed intensities shows close resemblance to the structure of the Laves phases of the C14-type. (author) [French] Au cours de recherches sur le systeme ternaire uranium-molybdene-silicium, on a constate la formation d'une nouvelle phase, de composition U{sub 4}Mo{sub 5}Si{sub 3}. Une determination de la structure, exclusivement fondee sur des donnees relatives a la poudre, a revele que cette phase particuliere appartenait au systeme hexagonal. Les auteurs indiquent un groupe spatial P6/mmc ou un des sous-groupes. Les dimensions d'une maille individuelle sont donnees par a = 5,37{sub 0}A, c = 8,58{sub 2}A. La comparaison entre l'intensite calculee et Tintensite observee montre une ressemblance etroite avec la structure des phases de Laves du type C-14. (author) [Spanish] En-el curso del estudio del sistema temario uranio-molibdeno-silicio, los autores observaron la formacion de una fase cuya composicion responde a la formula U{sub 4}Mo{sub 5}Si{sub 3}. La determinacion de la estructura, basada exclusivamente en los datos referentes al material en polvo, demuestra que esa fase pertenece al sistema hexagonal. Se senalo la existencia de un grupo especial P6/mmc y se comprobo que las dimensiones de la celda elemental son a = 5,37{sub 0}A, c = 8,58{sub 2}A. La comparacion de las intensidades calculadas con las observadas indica que existe una analogia estrecha con la estructura de la fase de Laves del tipo C 14. (author) [Russian] Pri izuchenii trojnoj sistemy uran - molibden - kremnij obrazovalas' novaya faza sostava U{sub 4}Mo{sub 5

  11. Vibrations of a molecule in an external force field.

    Science.gov (United States)

    Okabayashi, Norio; Peronio, Angelo; Paulsson, Magnus; Arai, Toyoko; Giessibl, Franz J

    2018-05-01

    The oscillation frequencies of a molecule on a surface are determined by the mass distribution in the molecule and the restoring forces that occur when the molecule bends. The restoring force originates from the atomic-scale interaction within the molecule and with the surface, which plays an essential role in the dynamics and reactivity of the molecule. In 1998, a combination of scanning tunneling microscopy with inelastic tunneling spectroscopy revealed the vibrational frequencies of single molecules adsorbed on a surface. However, the probe tip itself exerts forces on the molecule, changing its oscillation frequencies. Here, we combine atomic force microscopy with inelastic tunneling spectroscopy and measure the influence of the forces exerted by the tip on the lateral vibrational modes of a carbon monoxide molecule on a copper surface. Comparing the experimental data to a mechanical model of the vibrating molecule shows that the bonds within the molecule and with the surface are weakened by the proximity of the tip. This combination of techniques can be applied to analyze complex molecular vibrations and the mechanics of forming and loosening chemical bonds, as well as to study the mechanics of bond breaking in chemical reactions and atomic manipulation.

  12. Molecules in strong laser fields. In depth study of H{sub 2} molecule

    Energy Technology Data Exchange (ETDEWEB)

    Awasthi, Manohar

    2009-10-29

    A method for solving the time-dependent Schroedinger equation (TDSE) describing the electronic motion of the molecules exposed to very short intense laser pulses has been developed. The time-dependent electronic wavefunction is expanded in terms of a superposition of field-free eigenstates. The field-free eigenstates are calculated in two ways. In the first approach, which is applicable to two electron systems like H{sub 2}, fully correlated field-free eigenstates are obtained in complete dimensionality using configuration-interaction calculation where the one-electron basis functions are built from B splines. In the second approach, which is even applicable to larger molecules, the field-free eigenstates are calculated within the single-active-electron (SAE) approximation using density functional theory. In general, the method can be divided into two parts, in the first part the field-free eigenstates are calculated and then in the second part a time propagation for the laser pulse parameters is performed. The H{sub 2} molecule is the testing ground for the implementation of both the methods. The reliability of the configuration interaction (CI) based method for the solution of TDSE (CI-TDSE) is tested by comparing results in the low-intensity regime to the prediction of lowest-order perturbation theory. Another test for the CI-TDSE method is in the united atom limit for the H{sub 2} molecule. By selecting a very small value of the internuclear distance close to zero for the H{sub 2} molecule, Helium atom is obtained. Once the functionality and the reliability of the method is established, it is used for obtaining accurate results for molecular hydrogen exposed to intense laser fields. The results for the standard 800 nm Titanium-Sapphire laser and its harmonics at 400 nm and 266 nm are shown. The results for a scan over a wide range of incident photon energies as well as dependence on the internuclear distance are presented. The photoelectron spectra including

  13. Molecules in strong laser fields. In depth study of H2 molecule

    International Nuclear Information System (INIS)

    Awasthi, Manohar

    2009-01-01

    A method for solving the time-dependent Schroedinger equation (TDSE) describing the electronic motion of the molecules exposed to very short intense laser pulses has been developed. The time-dependent electronic wavefunction is expanded in terms of a superposition of field-free eigenstates. The field-free eigenstates are calculated in two ways. In the first approach, which is applicable to two electron systems like H 2 , fully correlated field-free eigenstates are obtained in complete dimensionality using configuration-interaction calculation where the one-electron basis functions are built from B splines. In the second approach, which is even applicable to larger molecules, the field-free eigenstates are calculated within the single-active-electron (SAE) approximation using density functional theory. In general, the method can be divided into two parts, in the first part the field-free eigenstates are calculated and then in the second part a time propagation for the laser pulse parameters is performed. The H 2 molecule is the testing ground for the implementation of both the methods. The reliability of the configuration interaction (CI) based method for the solution of TDSE (CI-TDSE) is tested by comparing results in the low-intensity regime to the prediction of lowest-order perturbation theory. Another test for the CI-TDSE method is in the united atom limit for the H 2 molecule. By selecting a very small value of the internuclear distance close to zero for the H 2 molecule, Helium atom is obtained. Once the functionality and the reliability of the method is established, it is used for obtaining accurate results for molecular hydrogen exposed to intense laser fields. The results for the standard 800 nm Titanium-Sapphire laser and its harmonics at 400 nm and 266 nm are shown. The results for a scan over a wide range of incident photon energies as well as dependence on the internuclear distance are presented. The photoelectron spectra including above

  14. The iodine molecule insights into intra- and intermolecular perturbation in diatomic molecules

    CERN Document Server

    Lukashov, Sergey; Pravilov, Anatoly

    2018-01-01

    This book presents experimental and theoretical spectroscopic studies performed over the last 25 years on the iodine molecule’s excited states and their perturbations. It is going to be of interest to researchers who study intra- and intermolecular perturbations in diatomic molecules and more complex systems. The book offers a detailed treatment of the nonadiabatic perturbations of valence, ion pair and Rydberg states induced by intramolecular as well as intermolecular interactions in collisions or in weakly-bound complexes. It also provides an overview of current instrumentation and techniques as well as theoretical approaches describing intra- and intermolecular perturbations. The authors are experts in the use of spectroscopy for the study of intrinsic and collision-induced perturbations in diatomic iodine. They introduced new methods of two- and three-step optical population of the iodine ion-pair states. The iodine molecule has 23 valence states correlating with three dissociation limits, 20 so-called ...

  15. Dynamics of hadronic molecule in one-boson exchange approach and possible heavy flavor molecules

    International Nuclear Information System (INIS)

    Ding Guijun; Liu Jiafeng; Yan Mulin

    2009-01-01

    We extend the one pion exchange model at quark level to include the short distance contributions coming from η, σ, ρ and ω exchange. This formalism is applied to discuss the possible molecular states of DD*/DD*, BB*/BB*, DD*, BB*, the pseudoscalar-vector systems with C=B=1 and C=-B=1 respectively. The ''δ function'' term contribution and the S-D mixing effects have been taken into account. We find the conclusions reached after including the heavier mesons exchange are qualitatively the same as those in the one pion exchange model. The previous suggestion that 1 ++ BB*/BB* molecule should exist, is confirmed in the one-boson exchange model, whereas DD* bound state should not exist. The DD*/DD* system can accommodate a 1 ++ molecule close to the threshold, the mixing between the molecule and the conventional charmonium has to be considered to identify this state with X(3872). For the BB* system, the pseudoscalar-vector systems with C=B=1 and C=-B=1, near threshold molecular states may exist. These bound states should be rather narrow, isospin is violated and the I=0 component is dominant. Experimental search channels for these states are suggested.

  16. Energy transfers between N_2(A"3Σ) nitrogen metastable molecules and oxygen atoms and molecules

    International Nuclear Information System (INIS)

    De Souza, Antonio Rogerio

    1985-01-01

    This research thesis aims at determining reaction coefficients for energy transfers between nitrogen in its metastable status and oxygen atoms and molecules, the variation of these coefficients with respect to temperature (mainly in the 200-400 K range), products formed and more particularly branching rates of O("1S) oxygen and of NO_2. Reaction coefficients are experimentally determined by using the technique of post-discharge in flow. The experimental set-up is described and the study of the best operating conditions is reported. In the next part, the author reports the study of the energy transfer between nitrogen in its metastable status N_2(A) and oxygen molecules. Reaction coefficients are determined for the first three vibrational levels. The author then reports the study of the transfer of N_2(A) molecules on oxygen atoms in their fundamental status. Reactions coefficients and their variations are determined for the three first vibrational levels. The author describes the dissociation method and the method of detection of atomic oxygen. A kinetic model is proposed for the analysis of formed products during a post-discharge in flow, and the branching rate for the formation of O("1S) oxygen between 190 and 365 K is determined. The author finally discusses publications on the role of these reactions in the interpretation of some atmospheric phenomena

  17. Perspective: Mechanochemistry of biological and synthetic molecules

    Energy Technology Data Exchange (ETDEWEB)

    Makarov, Dmitrii E., E-mail: makarov@cm.utexas.edu [Department of Chemistry and Institute for Computational Engineering and Sciences, University of Texas at Austin, Austin, Texas 78712 (United States)

    2016-01-21

    Coupling of mechanical forces and chemical transformations is central to the biophysics of molecular machines, polymer chemistry, fracture mechanics, tribology, and other disciplines. As a consequence, the same physical principles and theoretical models should be applicable in all of those fields; in fact, similar models have been invoked (and often repeatedly reinvented) to describe, for example, cell adhesion, dry and wet friction, propagation of cracks, and action of molecular motors. This perspective offers a unified view of these phenomena, described in terms of chemical kinetics with rates of elementary steps that are force dependent. The central question is then to describe how the rate of a chemical transformation (and its other measurable properties such as the transition path) depends on the applied force. I will describe physical models used to answer this question and compare them with experimental measurements, which employ single-molecule force spectroscopy and which become increasingly common. Multidimensionality of the underlying molecular energy landscapes and the ensuing frequent misalignment between chemical and mechanical coordinates result in a number of distinct scenarios, each showing a nontrivial force dependence of the reaction rate. I will discuss these scenarios, their commonness (or its lack), and the prospects for their experimental validation. Finally, I will discuss open issues in the field.

  18. Electron transport through a diatomic molecule

    International Nuclear Information System (INIS)

    Imran, Muhammad

    2014-01-01

    Electron transport through a diatomic molecular tunnel junction shows wave like interference phenomenon. By using Keldysh non-equilibrium Green's function (NEGF) theory, we have explicitly presented current and differential conductance calculation for a diatomic molecular and two isolated atoms (two atoms having zero hybridization between their energy orbitals) tunnel junctions. In case of a diatomic molecular tunnel junction, Green's function propagators entering into current and differential conductance formula interfere constructively for a molecular anti-bonding state and destructively for bonding state. Consequently, conductance through a molecular bonding state is suppressed, and to conserve current, conductance through anti-bonding state is enhanced. Therefore, current steps and differential conductance peaks amplitude show asymmetric correspondence between molecular bonding and anti-bonding states. Interestingly, for a diatomic molecule, comprising of two atoms of same energy level, these propagators interfere completely destructively for molecular bonding state and constructively for molecular anti-bonding state. Hence under such condition, a single step or a single peak is shown up in current versus voltage or differential conductance versus voltage studies.

  19. Indexing molecules with chemical graph identifiers.

    Science.gov (United States)

    Gregori-Puigjané, Elisabet; Garriga-Sust, Rut; Mestres, Jordi

    2011-09-01

    Fast and robust algorithms for indexing molecules have been historically considered strategic tools for the management and storage of large chemical libraries. This work introduces a modified and further extended version of the molecular equivalence number naming adaptation of the Morgan algorithm (J Chem Inf Comput Sci 2001, 41, 181-185) for the generation of a chemical graph identifier (CGI). This new version corrects for the collisions recognized in the original adaptation and includes the ability to deal with graph canonicalization, ensembles (salts), and isomerism (tautomerism, regioisomerism, optical isomerism, and geometrical isomerism) in a flexible manner. Validation of the current CGI implementation was performed on the open NCI database and the drug-like subset of the ZINC database containing 260,071 and 5,348,089 structures, respectively. The results were compared with those obtained with some of the most widely used indexing codes, such as the CACTVS hash code and the new InChIKey. The analyses emphasize the fact that compound management activities, like duplicate analysis of chemical libraries, are sensitive to the exact definition of compound uniqueness and thus still depend, to a minor extent, on the type and flexibility of the molecular index being used. Copyright © 2011 Wiley Periodicals, Inc.

  20. Thermal decomposition of irradiated casein molecules

    Energy Technology Data Exchange (ETDEWEB)

    Aly, M A; Elsayed, A A [Biophysics Dept., Faculty of Science, Cairo University, Giza (Egypt)

    1997-12-31

    Non-isothermal studies were carried out using the derivatograph where thermogravimetry (TG), and differential thermogravimetry (DTG) measurements were used to obtain the activation energies of the first and second reactions for casein decomposition before and after exposure to gamma rays and fast neutrons. Cf- 252 was used as a source of fast neutrons associated with gamma rays. TG and DTG patterns were also recorded for casein samples before and after irradiation with 1 Gy gamma-rays of 0.662 MeV from Cs - 137. However, no change in a activation energies were observed after exposure to gamma-irradiation. On the other hand, the activation energies for first and second reactions were found to be smaller at 0.4 m Gy than that at lower and higher neutron doses. However, no change in activation energies was observed after {gamma} irradiation. It is concluded from the present study that destruction of casein molecules by low level fast neutron doses may lead to changes of shelf storage period milk. 3 figs., 1 tab.