1,720,959 research outputs found
Synthesis and characterizations of amorphous carbon nanotubes/cadmium selenide quantum dots hybrid materials / Tan Kim Han
Get PDFCarbon nanotubes (CNTs) have attracted great attention. Most of the works being
conducted in the past mainly focus on the crystalline CNTs. In this work, amorphous
CNTs (α-CNTs) were synthesized successfully via a simple chemical technique at
230 °C in a short period of time. Surface morphological studies revealed that the asprepared
nanotubes present in straight tubular structures with open ends, having certain
dimensions (80 - 110 nm for outer diameter; 45 - 65 nm for inner diameter; 8 - 10 μm
for length). Both structural and elemental studies confirmed that the nanotubes were
made of amorphous carbon. Acidic purification and oxidation treatment caused the
surface of nanotubes rougher and introduced defects in their structures. Oxidation also
increased dispersion stability of nanotubes in deionised water and ensured the
successful hybridization between the α-CNTs and cadmium selenide (CdSe) quantum
dots (QDs). The α-CNTs displayed π plasmon absorbance phenomenon in ultravioletvisible
absorption spectra and had high band gap of 4.65 eV. The hybrid material
exhibited size quantization effect due to the attachment of CdSe QDs on the nanotubes
surfaces, giving the least band gap of 3 eV among the other samples. The presence of
two identical bands (D and G bands) in Raman spectra deduced that both the oxidation
and hybridization reduced crystallinity of the nanotubes substantially and confirmed the
existence of defective walls of the nanotubes that were composed of disordered carbon.
The α-CNTs exhibited lower permittivity in frequency range of 500MHz - 4.5 GHz due
to quantum size effects. However, the oxidation increased the permittivity of the α-
CNTs via chemical functionalization. Highest permittivity was found in the hybrid
material and it was the most thermally stable sample compared to others
Fabrication and optical behaviour of nanocomposites from electrodeposited au nanoparticles in polymer microcavities / Tan Kim Han
No full textMetal composites and artificial electromagnetic materials might have unusual electromagnetic properties including negative refractive index, highly effective permittivity and permeability values that could be tuned by controlling meta-atoms arrangement, the smallest resonant unit cells in these materials. In this work, a composite of gold nanoparticles (Au NPs) deposited within the polymeric arrays of fringes was demonstrated. The fabrication procedure was suggested by exploiting distinct electromagnetic properties between the ordered polymer molecules and different sizes of Au NPs. The synthesized Au NPs were electrodeposited in the well-ordered square microcavities of positive photoresist (PR) that were formed under electrophoretic deposition (EPD) at 30 DV for 120 sec. The surface plasmon resonance (SPR) of Au NPs and the flexibility of the photoresist (PR) polymer serving as a dielectric made them be used in preparing metal-dielectric nanocomposites. The cavities were constructed from UV-patterning of the PR that was spin-coated on indium tin oxide (ITO) substrate with the assist of copper grids as a photomask. The optical constants become smaller which the highest gain (real permittivity) with the lowest losses (imaginary permittivity) were obtained due to the well-ordered cavities containing the Au NPs. By depositing the Au NPs with different sizes in a relatively ordered manner within the polymeric material, the optical constants and electromagnetic properties of the thin film could be tuned accordingly to suit in applications such as superlens (subwavelength imaging), flat panel displays, optical sensing, and absorbing media
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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