1,721,450 research outputs found
Bi@C nanoparticles synthesized by laser ablation of solid in liquids
No full textEn este trabajo se presenta por primera vez, según la información disponible en la literatura, la obtención de nanopartículas (NPs) tipo núcleo-coraza de Bi@C, a partir de un blanco de bismuto inmerso en acetona, o en una solución coloidal de nanocebollas de carbono en agua destilada, mediante la técnica de ablación láser de sólidos en líquidos (ALSL). La síntesis de nanopartículas tipo núcleo-coraza (core-shell, en inglés) de bismuto (semi-metal) y carbono tanto cristalino como amorfo, es propuesta mediante un método rápido y eficiente a través de una ruta óptica. Estas NPs tipo Bi@C se desean utilizar como tratamiento a cáncer de mama. La fuente empleada fue un láser de estado sólido Nd:YAG de nanosegundos (Minilite II, Continuum) que produce pulsos de 7 ns, con frecuencia de repetición variable de 1 a 15 Hz y elección de longitud de onda entre el fundamental, el segundo, y el tercer armónico. En este trabajo se utilizaron dos longitudes de onda, con el propósito de comparar su influencia en las características de las nanopartículas obtenidas. Se muestra que existen diferencias significativas en las NPs que se obtuvieron, mediante la síntesis con las longitudes de onda 1064 nm (fundamental) y 532 nm (segundo armónico), principalmente en dos aspectos: el tipo de recubrimiento de carbono (cristalino o amorfo) y en las características de luminiscencia de las soluciones coloidales. Se utilizaron dos medios de inmersión (acetona y solución coloidal de carbono) para la síntesis de las NPs, con el propósito de determinar cuál de estos aporta de mejor manera la fuente de carbono para recubrir el núcleo de bismuto. Se demostró que la acetona produce un recubrimiento ya sea cristalino o amorfo en las NPs, y se determinó que la síntesis en este medio es la que produce las nanopartículas de Bi@C con las características deseadas. Las características principales de las NPs son discutidas en función de los parámetros de irradiación. La morfología, distribución de tamaño y su constitución core-shell, así como sus propiedades fotoluminiscentes, son analizadas. Finalmente, se discuten las aplicaciones potenciales de las NPs de Bi@C en el campo de la biomedicina; en este contexto se realizaron pruebas preliminares de citotoxicidad en dos líneas celulares, una línea de células sanas (células de riñón embrionario 293T), y una línea celular de cáncer de mama (MDA-MB-231), donde se obtuvieron resultados prometedores para continuar el estudio de las NPs de Bi@C ...This work presents, for the first time to the best of our knowledge, the synthesis of Bi@C core-shell nanoparticles (NPs). We used a bismuth blank immersed in either acetone or a carbon nano-onion colloidal solution in distilled water, synthesizing the Bi@C nanoparticles by using the laser ablation of solids in liquids technique (ALSL). The synthesis of core-shell Bi@C nanoparticles using a fully optical path through a fast and efficient method, is proposed. These Bi@C NPs are intended to be used as a treatment for breast cancer. A solid-state Nd: YAG laser (Minilite II, Continuum) that produces pulses of 7 ns duration, with variable repetition rate of 1 up to 15Hz was used for ALSL. In this work, the fundamental 1064nm and second harmonic 532nm wavelengths were used for the NPs synthesis, with the purpose of studying their influence on the characteristics of the obtained nanoparticles. It is shown that significant differences associated to the irradiation wavelength affect the NPs in two main aspects: the type of carbon shell (either crystalline or amorphous) and the photoluminescence features of the colloidal solutions. Two immersion media (acetone and colloidal carbon nano-onion solution) were used for the synthesis of the NPs, in order to determine which of these provides better the carbon source for the NPs shell. It was shown that acetone produces either a crystalline or amorphous shell on the NPs, and it was through this immersion liquid that the Bi@C NPs with desired characteristics were obtained. The main characteristics of the Bi@C NPs are discussed based on the irradiation parameters. Its morphology, size distribution and its core-shell constitution are analyzed, as well as its photoluminescence properties. Finally, the potential applications of these Bi@C NPs in the field of biomedicine are discussed. In this context, preliminary cytotoxicity tests were performed on two cell lines, a healthy one (embryonic kidney cells 293T), and a breast cancer cell line (MDA-MB-231). These preliminary tests yielded promising results to continue the study of Bi@C NPs as a therapeutic agent in cancer treatment
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
Tamshui Estuary Ecosystem I. Dynamic Distribution of Nutrients and Variation of Environmental Factors in Chuwei Swamp
No full textkoamabayili/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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