1,720,980 research outputs found
Preparation and Comparison of Hydrolase-Coated Plastics
Full text linkPolypropylene and polyethylene were coated with alpha-Chymotrypsin
(a-CT) or subtilisin Carlsberg (SubC) or Burkholderia
cepacia lipase (lipase BC) by different immobilization procedures,
such as physical adsorption and covalent linking. This
latter procedure was based on the chemical functionalization
of the plastic surface by oxygen gas plasma treatment. Immobilization
of the enzyme was carried out by using as cross-linking
agent i) glutaraldehyde (GA) or ii) N’-diisopropylcarbodiimide
(DIC) and N-hydroxysuccinimide (NHS). The effects of duration
of the plasma treatment and the type of the immobilization
procedure on the transesterification activity of the enzyme
were investigated. In general polypropylene resulted a better
support than polyethylene. Moreover, a-CT showed higher
transesterification activity when immobilized with GA, while for
SubC, DIC and NHS were better cross-linking agents than GA.
No activity was observed with these enzymes when immobilization
was carried out by physical adsorption. On the contrary,
lipase BC immobilized by physical adsorption was even more
active than the free enzyme. Concerning thermal stability, immobilized
SubC was less stable than the free enzyme. Overall,
these results show that plastics endowed with biocatalytic
properties could be obtained by simple immobilization protocols
and that optimal immobilization conditions depend on the
type of starting plastic, plasma treatment, cross-linking method,
and the nature of the enzyme
Electroless synthesis of metallic nanostructures for biomedical technologies
No full textThe electroless deposition of metals has emerged as one of the leading growth areas in surface engineering
and metal finishing, and, recently, it is gaining interest for the synthesis of metallic nanostructures
for biomedical technologies. In this perspective, the fundamental aspects underlying the autocatalytic
deposition (ACD) and immersion plating are briefly reviewed, establishing the unique identity of galvanic
displacement among electrochemical processes in general, and electroless processes in particular.
Numerous biological and biomedical phenomena occur at the nanometer level, and the current research
focus of many fields is nanotechnology. Nanostructured metallic systems can provide the ability to probe
the sub-optical, molecular level and are becoming powerful tools to study biomolecular processes. Metal
nanosystems also hold great promise for the field of nanomedicine, where nanostructures are designed
to diagnose and provide therapy at the single-cell level. The exploitation of the electroless methods as
an amazingly simple and effective route for generating metal nanostructures will be reviewed within
the frame of biomedical technologies, discussing the applications in sensors and microdevices, the
preparation and use of nanostructured metals for supporting and wiring biomolecules, for DNA analysis
and disease screening. The use of nanostructures such as nanorods and nanoparticles, as these structures show interesting optical, electrical, and mechanical properties, will be analyzed in view of their potential
applications in nanobiotechnology
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
Altered uterine contractility pattern in the periovulatory phase of womem with chronic endometritis
No full text
Purification and characterization of a novel recombinant highly enantioselective ,short-chain NAD(H)-dependent alcohol dehydrogenase from Thermus thermophilus
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