1,720,966 research outputs found
Spontaneous formation of gold nanostructures in aqueous microdroplets
Get PDFAbstractThe synthesis of gold nanostructures has received widespread attention owing to many important applications. We report the accelerated synthesis of gold nanoparticles (AuNPs), as well as the reducing-agent-free and template-free synthesis of gold nanoparticles and nanowires in aerosol microdroplets. At first, the AuNP synthesis are carried out by fusing two aqueous microdroplet streams containing chloroauric acid and sodium borohydride. The AuNPs (~7 nm in diameter) are produced within 60 µs at the rate of 0.24 nm µs−1. Compared to bulk solution, microdroplets enhance the size and the growth rate of AuNPs by factors of about 2.1 and 1.2 × 105, respectively. Later, we find that gold nanoparticles and nanowires (~7 nm wide and >2000 nm long) are also formed in microdroplets in the absence of any added reducing agent, template, or externally applied charge. Thus, water microdroplets not only accelerate the synthesis of AuNPs by orders of magnitude, but they also cause spontaneous formation of gold nanostructures.</jats:p
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Engineered Artificial Enzymes for Biosensor Applications
Get PDFFunctional nucleic acids (FNAs) have revolutionized the fields of chemical measurements and imaging, particularly through their catalytic properties which have facilitated the highly sensitive detection of various analytes in complex environments. Despite the rapid increase in the capabilities of catalytic FNAs, their applications in sensing and imaging technologies lag behind those of traditional enzymes. This research focuses on narrowing this gap to explore and enhance the catalytic capabilities of FNAs, including DNA-functionalized cofactors. One of the central challenges in this field is the intricate task of designing catalysts that emulate the complex three-dimensional structure of natural enzyme active sites. This endeavor has led to innovative strategies, including the optimization of the hemin-iron catalytic center found in Horse Radish Peroxidase (HRP). A notable advancement involves the integration of G-quadruplex structures with Hemin, providing a conducive environment for the cofactor. This "self-assembly" method enhances hemin's catalytic activity by protecting it from environmental factors, such as optimal temperature and pH ranges, that typically lead to enzymatic deactivation. By exploring the integration of novel functionalities and enhancing the catalytic efficiency of these artificial enzymes, we pave the way for broader applications that could revolutionize biotechnological processes and medical diagnostics. DNA-Hemin’s enhanced performance and versatility therefore opens new avenues for the sensitive detection of biomarkers and new paradigms in disease diagnosis, bioengineering, and synthetic biology. This research exemplifies the dynamic and evolving nature of bioengineering, promising a future where synthetic biocatalysts play a pivotal role in a wide array of industrial and healthcare solutions.Chemistr
UNCONVENTIONAL SUPERHALOGENS: DESIGN AND APPLICATIONS
Get PDFElectron affinity is one of the most important parameters that guide chemical reactivity. Halogens have the highest electron affinities among all elements. A class of molecules called superhalogens has electron affinities even greater than that of Cl, the element with the largest electron affinity (3.62 eV). Traditionally, these are metal-halogen complexes which need one electron to close their electronic shell. Superhalogens have been known to chemistry for the past 30 years and all superhalogens investigated in this period are either based on the 8-electron rule or the 18-electron rule. In this work, we have studied two classes of unconventional superhalogens: borane-based superhalogens designed using the Wade-Mingo’s rule that describes the stability of closo-boranes, and pseudohalogen based superhalogens. In addition, we have shown that superhalogens can be utilized to build hyperhalogens, which have electron affinities exceeding that of the constituent superhalogens, and also to stabilize unusually high oxidation states of metals
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
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