1,720,955 research outputs found
ESTUDIO TEÓRICO DE NANOTUBOS DE CARBONO FUNCIONALIZADOS
No full textLos nanotubos de carbono son considerados acarreadores biológicos es por
ello que son funcionalizados para transportar moléculas de interés biológico,
incluyendo, proteínas y antibióticos, entre otras. En el presente estudio se
analizaron dos vías de funcionalización: a través de enlaces directos y por
medio de moléculas intermedias o “puente”, utilizando la teoría de funcionales
de la densidad y con una metodología B3LYP/ 6-31G. Se analizaron las
moléculas intermedias: N-BOC-2,2 dioxietileno dietilamina, N-BOC-2,
2´iminodietilamina, BOC-β-Homolgn-OH, (N-BOC-β-amino)-Ala-OH, N-boc-
1,2-fenilenediamina, N-BOC-1,6-hexanediamina,(BOC-D-Gln-ONp,BOCGln,OSu),
nanotubos de carbono y una secuencia de aminoácidos específicas
de la lectina. Por medio de cálculos de energía se determinaron sitios reactivos
utilizando funciones de Fukui condensadas, además propiedades de
reactividad química para las diferentes moléculas intermedias o “puentes”,
encontrándose que el puente BOC-D-Gln-ONp es el único con una afinidad
electrónica positiva, menor dureza química y mayor electrofilicidad. Además se
calcularon energías de formación dando como resultado que en ambos tipos de
funcionalización ya sea por medio de enlaces directos o por moléculas
intermedias o puentes, se requiere administrarles energía para que se lleven a
cabo las reacciones y por ello se podría prescindir del uso de moléculas
intermedias.Carbon nanotubes are considered biological carriers, is why we are
functionalized to transport biological molecules, including proteins and
antibiotics, among others. This study considered two ways of functionalization:
through direct links and through intermediate molecules or “linkers”, using the
theory of density functional and methodology B3LYP/6-31G. Intermediate
molecules were analyzed: N-BOC-2, 2 dioxyethylene diethylamine, N-BOC-2,
2'iminodiethylamine, BOC-β-Homolgn-OH, (N-BOC-β-amino)-Ala-OH, N-boc-1
,2-phenylenediamine, N-BOC-1 ,6-hexanediamine, BOC-D-Gln-ONp, (BOC-Gln,
OSu), carbon nanotubes and specific amino acid sequence of the lectin.
Through energy calculations reactive sites were determined using condensed
Fukui functions, in addition to chemical reactivity properties of the different
intermediate molecules or “linkers” finding that the bridge BOC-D-Gln_ONp is
the only one with a positive electron affinity, lower hardness and greater
electrophilicity chemistry. Moreover formation energies were calculated with
the result that in both types of functionalization either through direct lionks or
intermediate molecules or linkers, administering energy required for the
carrying out reactions and therefore could dispense with the use of
intermediate molecules
ESTUDIO TEÓRICO-EXPERIMENTAL DE FUNCIONALIZACIÓN DE NANOTUBOS DE CARBONO CON MOLÉCULAS BIOLÓGICAS POR MÉTODO DE AMIDACIÓN UTILIZANDO DIFERENTES ACTIVADORES
Get PDFLa funcionalización de nanotubos de carbono (NTC) se basa en la modificación de la estructura ya sea por medio de interacciones covalentes y no covalentes incluyendo ocasionalmente el llenado de la cavidad de los NTC. Las reacciones de amidación en NTC han sido ampliamente usadas ya que ofrecen alta estabilidad al complejo formado. Sin embargo, estas reacciones no son favorecidas termodinámicamente por lo que es necesario el uso de activadores como las carbodiimidas. En este trabajo se propone el estudio de otras carbodiimidas existentes así como el uso de nuevos activadores como ligasas C-N ya que estas actúan como catalizadores naturales. Además se propone el uso del anhídrido propilfosfonico (T3P), el cual es utilizado en la síntesis de péptidos al igual que las carbodiimidas, sin embargo, el T3P presenta mayores ventajas en comparación con las carbodiimidas, al ser un reactivo verde ya que no es tóxico, no alergénico y no sensible, además el subproducto se obtiene en forma de sal y completamente soluble en agua. La propuesta de trabajo consiste en un estudio teórico, el cual se llevó a cabo empleando Gaussian 09 con un visualizador gráfico Gauss View 5.0.Se utilizó DFT con el funcional B3LYP y el conjunto de base 6-31G (d). Se obtuvieron energías de formación de las reacciones de amidación utilizando las diferentes carbodiimidas, T3P, NTC, arginina y un péptido (estructura conservada de Lectina). Por otra parte se usó el programa AutoDock para identificar los acoplamientos tanto del NTC como del péptido propuestos con diferentes enzimas de tipo ligasa C-N. La parte experimental se llevó a cabo después de obtener los resultados teóricos. Se realizó la síntesis y purificación NTC y los activadores empleados para las reacciones de amidación fueron: 1-etil-3-(3-dimetilaminopropil) carbodiimida) (EDC)-(CD4) y N, N'-diciclohexilcarbodiimida (DCC)-(CD8) y el anhídrido propilfosfonico (T3P), además del uso de arginina como molécula de interés biológico. Los resultados teóricos encontrados muestran que las diferentes carbodiimidas son buenos candidatos como activadores para llevar a cabo la reacción de amidación, sin embargo, las reacciones de amidación donde se utiliza el activador T3P son reacciones no espontáneas, por lo que será necesario adminístrales energía. La enzima se adsorberá sobre la superficie del NTC, mientras que el péptido propuesto no tiene afinidad de unirse a las enzimas. Los resultados experimentales muestran que todas las reacciones de amidación se llevaron a cabo, sin embargo, para la reacción donde interviene el T3P como activador presenta el mayor porcentaje de nitrógeno, lo que la hace la reacción más eficiente
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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