Search results for "Ribb"
showing 10 items of 153 documents
HYDROIDS OF THE FAMILIY AGLAOPHENIIDAE FROM THE COLOMBIAN CARIBBEAN CONTINENTAL SHELF AND UPPER SLOPE
2010
Se realizó un estudio taxonómico de los hidrozoos de la familia Aglaopheniidae colectados sobre fondos blandos del Caribe colombiano entre 20 y 500 m de profundidad en marzo de 2001 por la expedición INVEMAR MACROFAUNA II. Fueron encontrados dos géneros y seis especies destacándose Aglaophenia elongata, A. lophocarpa y A. tridentata como nuevos registros para aguas colombianas y además se amplió la distribución batimétrica de Aglaophenia latecarinata y A. tridentata. En general los caracteres morfológicos de las especies estudiadas no presentaron diferencias significativas con respecto a las descripciones taxonómicas realizadas por otros autores En esta publicación se consignan las fichas t…
Efficient Approach for Simulating Distorted Materials
2010
The operation principles of nanoscale devices are based upon both electronic and mechanical properties of materials. Because these properties can be coupled, they need to be investigated simultaneously. At this moment, however, the electronic structure calculations with custom-made long-range mechanical distortions are impossible, or expensive at best. Here we present a unified formalism to solve exactly the electronic structures of nanomaterials with versatile distortions. We illustrate the formalism by investigating twisted armchair graphene nanoribbons with the least possible number of atoms. Apart from enabling versatile material distortions, the formalism is capable of reducing computa…
Graphene nanoribbons subject to gentle bends
2012
Since graphene nanoribbons are thin and flimsy, they need support. Support gives firm ground for applications, and adhesion holds ribbons flat, although not necessarily straight: ribbons with high aspect ratio are prone to bend. The effects of bending on ribbons' electronic properties, however, are unknown. Therefore, this article examines the electromechanics of planar and gently bent graphene nanoribbons. Simulations with density-functional tight-binding and revised periodic boundary conditions show that gentle bends in armchair ribbons can cause significant widening or narrowing of energy gaps. Moreover, in zigzag ribbons sizeable energy gaps can be opened due to axial symmetry breaking,…
Twisting graphene nanoribbons into carbon nanotubes
2011
Although carbon nanotubes consist of honeycomb carbon, they have never been fabricated from graphene directly. Here, it is shown by quantum molecular-dynamics simulations and classical continuum-elasticity modeling, that graphene nanoribbons can, indeed, be transformed into carbon nanotubes by means of twisting. The chiralities of the tubes thus fabricated can be not only predicted but also externally controlled. This twisting route is an opportunity for nanofabrication, and is easily generalizable to ribbons made of other planar nanomaterials.
Copper(II)–Thymine Coordination Polymer Nanoribbons as Potential Oligonucleotide Nanocarriers
2016
This is the peer reviewed version of the following article: Vegas, V. G., Lorca, R., Latorre, A., Hassanein, K., Gómez‐García, C. J., Castillo, O., ... & Amo‐Ochoa, P. (2017). Copper (II)–Thymine Coordination Polymer Nanoribbons as Potential Oligonucleotide Nanocarriers. Angewandte Chemie International Edition, 56(4), 987-991, which has been published in final form at https://doi.org/10.1002/anie.201609031. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions
Population status of the American crocodile, Crocodylus acutus (Reptilia: Crocodilidae) and the caiman, Caiman crocodilus (Reptilia: Alligatoridae), …
2019
Two species of crocodilians have been described in Costa Rica, American crocodile, Crocodylus acutus (Cuvier, 1807), and caiman, Caiman crocodilus (Linnaeus 1758). In Costa Rica, data has been generated on both species, but populations in the Pacific have received more attention from researchers; presumably due to the fact that the Pacific slope has a greater development, which brings greater social pressure on the attention of the incidents generated by the encounter between humans and crocodiles. This study, performed during 2017, was done in an area of approximately 400 km2, characterized by having a wide and dense network of water courses, which includes the Matina, Pacuare, Reventazón …
"Per via di levare". Scavare e sottrarre in architettura
2014
Scavare, dal latino excavare (ex-cavare), possiede etimologicamente il significato di “rendere cavo” mediante l’azione del subtrahĕre (sottrarre). Tuttavia il significato del termine all’interno della sua necessaria disambiguazione non può essere inteso limitatamente alla luce dell’etimologia latina. Si dirà allora che la tecnica dello scavo è opposta e complementare alla tecnica dell’accumulazione. È un procedere per sottrazione di volumi, un operare in negativo per asportazione di materiale, erodendo, cavando ed estraendo. Il saggio indaga, attraverso un intenso per quanto lacunoso excursus tra le esperienze della contemporaneità l'emergere del archetipico della dimensione ipogea dell’arc…
Una revisión histórico-política de la producción literaria puertorriqueña. Entrevista con Fernando Feliú Matilla / A historical and political review …
2017
Resumen: A lo largo de la siguiente entrevista, el profesor, historiador, crítico e investigador la de la Universidad de Puerto Rico, el catedrático en literatura puertorriqueña don Fernando Feliú Matilla, nos permite establecer una visión histórica de la génesis artística llevada a cabo en la Isla a través de los diferentes contextos socio-políticos que han tenido lugar en la misma desde la aparición de una literatura puertorriqueña propia y distintiva hasta la anexión de Puerto Rico a los Estados Unidos de América como Estado Libre Asociado en 1952 y su impronta en la génesis isleña. Si bien la entrevista tiene como objeto principal la literatura boricua, también se debaten en la misma el…
The Marvelous History of the Dominican Republic in Junot Diaz's The Brief Wondrous Life of Oscar Wao
2013
Few things are as noticeable in Junot Diaz’s The Brief Wondrous Life of Oscar Wao (2007) as its references to a wide variety of movies, TV series, comics, and most centrally to fantasy, the genre in which worlds are created that allow for the existence of magic, monsters, and other elements of the marvelous. Interweaving the story of the fictional Cabral family in the Dominican Republic and in the diaspora with the history of the dictatorship of Rafael Trujillo (1930–1961), the novel offers a sweeping reinterpretation of Caribbean history in a way that is completely intelligible only if one understands the relevance of its primary fantasy intertext, The Lord of the Rings (1954–55), both for…
Time-dependent Landauer-Büttiker formula: Application to transient dynamics in graphene nanoribbons
2014
In this work we develop a time-dependent extension of the Landauer-B\"uttiker approach to study transient dynamics in time-dependent quantum transport through molecular junctions. A key feature of the approach is that it provides a closed integral expression for the time-dependence of the density matrix of the molecular junction after switch-on of a bias or gate potential which can be evaluated without the necessity of propagating individual single-particle orbitals. This allows for the study of time-dependent transport in large molecular systems coupled to wide band leads. As an application of the formalism we study the transient dynamics of zigzag and armchair graphene nanoribbons of diff…