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Search Results: 1 - 10 of 239 matches for " Marine Kvaraia "
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Quantum-Chemical Description of Influence of the R-Groups on Formation of Peptide Bond  [PDF]
Jumber Kereselidze, Marine Kvaraia, George Mikuchadze
Computational Molecular Bioscience (CMB) , 2014, DOI: 10.4236/cmb.2014.42004
Abstract: The description of influence of the R-groups on formation of the peptide bond by quantum-chemical method of density functional theory (DFT) is carried out. The criterion of probability of formation of the peptide bond has been constructed. In particular it is shown that the propensity to formation of the peptide bond is increased as a result of 1) decrease of the CO and NH bond orders (PCO and PNH) and of activation energy (ΔE#), 2) increase of OH and CN bond orders (POH and PCN), 3) exothermic property of this reaction (ΔE < 0).
Chemical Bonds between Charged Atoms in the Even-Odd Rule and a Limitation to Eight Covalent Bonds per Atom in Centered-Cubic and Single Face-Centered-Cubic Crystals  [PDF]
Geoffroy Auvert, Marine Auvert
Open Journal of Physical Chemistry (OJPC) , 2015, DOI: 10.4236/ojpc.2015.54010
Abstract: A crystal is a highly organized arrangement of atoms in a solid, wherein a unit cell is periodically repeated to form the crystal pattern. A unit cell is composed of atoms that are connected to some of their first neighbors by chemical bonds. A recent rule, entitled the even-odd rule, introduced a new way to calculate the number of covalent bonds around an atom. It states that around an uncharged atom, the number of bonds and the number of electrons have the same parity. In the case of a charged atom on the contrary, both numbers have different parity. The aim of the present paper is to challenge the even-odd rule on chemical bonds in well-known crystal structures. According to the rule, atoms are supposed to be bonded exclusively through single-covalent bonds. A distinctive criterion, only applicable to crystals, states that atoms cannot build more than 8 chemical bonds, as opposed to the classical model, where each atom in a crystal is connected to every first neighbor without limitation. Electrical charges can be assigned to specific atoms in order to compensate for extra or missing bonds. More specifically the article considers di-atomic body-centered-cubic, tetra-atomic and dodeca-atomic single-face-centered-cubic crystals. In body-centered crystals, atoms are interconnected by 8 covalent bonds. In face-centered crystal, the unit cell contains 4 or 12 atoms. For di-element crystals, the total number of bonds for both elements is found to be identical. The neutrality of the unit cell is obtained with an opposite charge on the nearest or second-nearest neighbor. To conclude, the even-odd rule is applicable to a wide number of compounds in known cubic structures and the number of chemical bonds per atom is not related to the valence of the elements in the periodic table.
The Even-Odd and the Isoelectronicity Rules Applied to Single Covalent Bonds in Ionic, Double-Face-Centered Cubic and Diamond-Like Crystals  [PDF]
Geoffroy Auvert, Marine Auvert
Open Journal of Physical Chemistry (OJPC) , 2016, DOI: 10.4236/ojpc.2016.62002
Abstract: Although atom configuration in crystals is precisely known thanks to imaging techniques, there is no experimental way to know the exact location of bonds or charges. Many different representations have been proposed, yet no theory to unify conceptions. The present paper describes methods to derive bonds and charge location in double-face-centered cubic crystals with 4 and 6 atoms per unit cell using two novel rules introduced in earlier works: the even-odd and the isoelectronicity rules. Both of these rules were previously applied to ions, molecules and some solids, and the even-odd rule was also tested on two covalent crystal structures: centered-cubic and single-face-centered cubic crystals. In the present study, the diamond-like structure was subjected to the isoelectronicity rule in order to derive Zinc-blende structures. Rock-salt-like crystals were derived from each other using both rules. These structures represent together more than 230 different crystals. Findings for these structures are threefold: both rules describe a very sure method to obtain valid single covalent-bonded structures; single covalent structures can be used in every case instead of the classical ionic model; covalent bonds and charges positions do not have any relation with the valence number given in the periodic table.
Introducing an Extended Covalent Bond between Oxygen Atoms with an OXO-Shape in Ions and Molecules: Compatibility with the Even-Odd and the Isoelectronicity Rules  [PDF]
Geoffroy Auvert, Marine Auvert
Open Journal of Physical Chemistry (OJPC) , 2016, DOI: 10.4236/ojpc.2016.63007
Abstract: Building on the recent success of the even-odd rule, the present paper explores its implications by studying the very specific case of OXO compounds. These compounds are usually represented with double bonds linking two oxygen atoms to a central atom—as in carbon dioxyde—yet can sometimes be drawn in a triangular structure, such as in calcium dioxyde. Measurement data moreover indicate that most OXO compounds have an angle around 120° between oxygen atoms, although that seems incompatible with triangular representations. The aim here is to unify these commonly admitted representations by linking oxygen atoms through a single bond that is longer than usual covalent bonds: an “elongated bond”. This elongated bond has the interesting effect of suppressing the need for double bonds between oxygen and the central atom. The elongated bond concept is applied to about a hundred of molecules and ions and methodically compared to classical representations. It is shown that this new representation, associated to the even-odd rule, is compatible with all studied compounds and can be used in place of their classical drawings. Its usage greatly simplifies complex concepts like resonance and separated charges in gases. Elongated bonds are also shown to be practicable with the isoelectronic rule as well as isomers, and throughout chemical reactions. This study of an especially long and wide angle bond confirms the versatility of the even-odd rule: it is not limited to compounds with short covalent bonds and can include OO covalent bond lengths of more than 200 pm and with OXO angles above 90°.
The Citizen, the Culture and European Union
Marine Imberechts
Acta Universitatis Danubius : Relationes Internationales , 2009,
Abstract: From the beginning of its work (1988), the European Centre of Culture tried to attract theattention of the European institutions on the urgent need to bring in the greatest number of citizens asense of belonging to a new space and a common destiny based on a common culture.
Habiter un quartier RDP
Marine Suteau
EchoGéo , 2010,
Abstract: Cet article porte sur les processus de différentiation et d’appropriation socio-spatiale dans un quartier d’habitat social issu des programmes de Reconstruction et de Développement (RDP) post-apartheid. Situé dans lesplaines sableuses du Cap, le quartier périphérique de Delft South pose le débat de l’évolution des quartiers RDP dans les villes sud-africaines. Dans le contexte post-apartheid, les stratégies d’accès à la propriété et les résistances locales participent à la production de territoires appropriés, différenciés et revendiqués. Les communautés de rues, fondées sur les solidarités mixtes de voisinage, illustrent les recompositions socio-spatiales en quartier RDP. This article focuses on a socio-spatial analysis of territorial change in Cape Town over timewith the study of Delft South as a post-apartheid low-cost housing development program. It asks how successful or not RDP programs have been in South African cities. It argues that social differentiation is in process. In the post-apartheid, strategies to access housing and social movements are producing socio-spatial territories. Through housing and socio-spatial networks inherited from street committees, Delft South may constitute a complex peripheral space with the creation of specific racially mixed neighborhoods.
Tsidy, Repahaka sy Fotsife: 15 years research on nocturnal lemurs in the Ankarafantsika National Park, Madagascar Tsidy, Repahaka sy Fotsife :15 ans de recherche sur les lémuriens nocturnes dans le Parc National d′Ankarafantsika, Madagascar
Marine Joly
Revue de Primatologie , 2011, DOI: 10.4000/primatologie.758
Abstract: Tsidy, Repahaka sy Fotsife from the Malagasy: Mouse lemur, sportive lemur and woolly lemur. "The Ankarafantsika Lemur Project", is based at the field station of Ampijoroa in the National Park of Ankarafantsika in the North-West of Madagascar and is conducted by the Institute of Zoology from the University of Veterinary Medicine Hanover (Germany) in close collaboration with the local universities of Antananarivo, of Mahajanga and Madagascar National Parks (authorities for the management of protected areas in Madagascar). The project started in 1996. The goal is to enhance our knowledge on the adaptation and evolution of a previously neglected group of primates, the nocturnal lemurs, and to contribute to their conservation. Thus, researchers study the diversity, ecology, communication and socio-biology of the nocturnal lemurs. They discovered one new mouse lemur species (Microcebus ravelobensis) in this area. They characterised aspects of the morphometry, genetics, communication, ecology, social traits and recently, cognitive abilities of sympatrically living mouse-sized (Microcebus murinus and M. ravelobensis) and cat-sized lemur species (Lepilemur edwardsi and Avahi occidentalis). Some major results are presented in this article showing the importance of exchanging experience, educating Malagasy students and field guides and joint work with Malagasy partners in order to deepen our knowledge on the biology of endemic species. This knowledge is crucial to establish efficient management plans and thus contribute to the conservation of threatened species. Tsidy, Repahaka sy Fotsife en langue Malgache : Microcèbe, Lépilémur et Avahi. Le projet de recherche sur les lémuriens nocturnes d′Ankarafantsika est basé à la station d′Ampijoroa dans le Parc National d′Ankarafantsika dans le nord-ouest de Madagascar. Il est mené par l′Institut de Zoologie de l′Ecole Vétérinaire de Hanovre (Allemagne) en collaboration étroite avec les universités locales d'Antananarivo, Mahajanga ainsi que Madagascar National Parks (autorité chargée de gérer les aires protégées de l′ le). Le projet a débuté en 1996. Son but est d′améliorer les connaissances sur l′évolution et l′adaptation d′un groupe de primates souvent négligé, les lémuriens nocturnes, et de contribuer à leur conservation. Pour cela, les chercheurs ont mené de nombreuses études sur la diversité, l′écologie, la communication, la sociobiologie des lémuriens nocturnes dans cette région. Après avoir fait la découverte d′une nouvelle espèce de microcèbe (Microcebus ravelobensis), les chercheurs ont également caractérisé la m
Le journal humoristique El Papus (1973-1986). Contre-culture et transgression pendant la transition démocratique espagnole
Marine Lopata
Comicalités : études de Culture Graphique , 2012, DOI: 10.4000/comicalites.988
Abstract: Au sein de la presse humoristique qui voit le jour en Espagne au début des années soixante-dix, la revue El Papus (1973-1986) se démarque par son ton provocateur et son go t prononcé pour la provocation et la transgression de tous les tabous sociaux, politiques et culturels de l’époque. C’est à cet aspect inédit que nous consacrerons la première partie de la présente étude, nous verrons ainsi qu’aussi bien le projet de création, que l’équipe de rédaction, l’esthétique et les thématiques d’El Papus se caractérisent par leur dimension transgressive. L’analyse des deux sujets phares du journal : la politique et le sexe, nous permettra d’envisager la revue El Papus comme produit de contre-culture. Finalement, nous nous interrogerons sur l’impact du journal au sein de la société espagnole durant la Transition démocratique. Within the humoristic press that appeared in Spain at the beginning of the seventies, the El Papus journal (1973-1986) stands out for its taste for provocation and transgression of all social, political and cultural taboos of that time. It is precisely about this feature that the first part of this study will talk about – we shall see how the creation project, as well as the editorial board, the aesthetics and the topics of El Papus are defined by their destructive dimension. The analysis of the two main subjects of the review, politics and sex, will let us consider the review as a product of counter-culture. Finally, we will examine the impact of the review within the Spanish society of the democratic Transition.
Yémen nouveau, futur meilleur ? “New Yemen and a brighter future ?” Getting back to the 2006 presidential election
Marine Poirier
Chroniques Yéménites , 2008,
Abstract: Si l’élection présidentielle du 20 septembre 2006 reconduit ‘Al ‘Abd Allah /Sali/h au sommet de l’ état avec 77% des voix, elle ne marque pas moins une transformation majeure de la scène politique yéménite. Pour la première fois, le président est mis en situation de compétition électorale par une opposition qui, en se réunissant autour d’un candidat unique, parvient à transcender le clivage opposant traditionnellement les partisans de la gauche aux formations islamistes. Cependant, la rénovation de l’enjeu électoral n’éloigne pas significativement le Yémen de la norme institutionnelle arabe , le régime s’assurant du verrouillage autoritaire du scrutin. Quel est donc l’effet élection 2006 ? Dans quelle mesure le jeu politique a-t-il été durablement remodelé par l’introduction de la concurrence ? En offrant des horizons pluralistes sans toutefois contrarier les dynamiques de personnalisation du pouvoir, l’élection n’a-t-elle pas favorisé l’essor de nouvelles formes de contestation politique ? If the presidential election of September 2006 confirmed ‘Al ‘Abd Allah /Sali/h at the head of the State with 77% of the votes, it nonetheless represents a major transformation of Yemeni political scene. For the first time, the president was confronted to electoral contest, as the opposition, gathered around a unique candidate, succeeded in surpassing the traditional leftist - islamist antagonism. However, the renewal of the electoral stake has not really averted Yemen from the “Arab institutional norm”, the regime ensuring an authoritarian lock of the poll. What is, then, the “2006 election” effect? To which extent has the political game been durably remodelled? By offering pluralist prospects without challenging the dynamics of personalization of power, hasn’t the election encouraged the rise of new forms of political contestation?
Yemen’s Democracy Experiment in Regional Perspective. Patronage and Pluralized Authoritarianism, by Sarah Phillips.
Marine Poirier
Chroniques Yéménites , 2010,
Abstract: Si un certain nombre de publications récentes s’intéressent aux dynamiques politiques et partisanes dans le Yémen contemporain, peu s’attachent à explorer la bo te noire de l’état yéménite et notamment les processus d’ajustement et de maintien du régime de ‘Al ‘Abd Allah /Sali/h. Voici justement l’objet de l’ouvrage de Sarah Phillips, qui examine la nature des transformations des structures de pouvoir, des espaces politiques publics et des institutions politiques au Yémen depuis l’unité ...
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