305,184 research outputs found
Interactions between heavy metals and photosynthetic materials studied by optical techniques
Get PDFIn this work studies on rapid inhibitory interactions between heavy metals and
photosynthetic materials at different organization levels were carried out by
optical assay techniques, investigating the possibility of applications in the
heavy metal detection field. Spinach chloroplasts, thylakoids and Photosystem II
proteins were employed as biotools in combination with colorimetric assays based
on dichlorophenol indophenole (DCIP) photoreduction and on fluorescence emission
techniques. It was found that copper and mercury demonstrated a strong and rapid
photosynthetic activity inhibition, that varied from proteins to membranes,
while other metals like nickel, cobalt and manganese produced only slight
inhibition effects on all tested photosynthetic materials. By emission
measurements, only copper was found to rapidly influence the photosynthetic
material signals. These findings give interesting information about the rapid
effects of heavy metals on isolated photosynthetic samples, and are in addition
to the literature data concerning the effects of growth in heavy metal enriched
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
Development of a sensor prepared by entrapment of MIP particles in electrosynthesised polymer films for electrochemical detection of ephedrine
No full textA voltammetric sensor for (−)-ephedrine has been prepared by a novel approach based on immobilisation of an imprinted polymer for ephedrine
(MIPE) in an electrosynthesised polypyrrole (PPY) film. Composite films were grown potentiostatically at 1.0V vs. Pt (QRE) on a glassy carbon
electrode using an unconventional “upside-down” (UD) geometry for the three-electrode cell. As a consequence, a high MIP loading was obtained,
as revealed by SEM. The sensor response was evaluated, after overoxidation of PPY matrix, by cyclic voltammetry after pre-concentration in
a buffered solution of analyte in 0.5–3mM concentration range. An ephedrine peak at ≈0.9V increasing with concentration and saturating at
high concentrations was evident. PPY-modified electrode showed a response, which was distinctly lower than the MIP response for the same
concentration of the template. The effect of potential interferences including compounds usually found in human fluids (ascorbic acid, uric acid,
urea, glucose, sorbitol, glycine, dopamine) was examined
Development of a new MIP-based sensor based on MIP particles entrapment in electrosynthetized polymer films
No full textDispelling 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
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
Get PDFThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
Surface functionalization of porous polypropylene membranes with polyaniline for protein immobilization
No full textCommercial porous polypropylene membranes were chemically modified with polyaniline (PANI) using ammonium persulfate as the oxidizer. The influence of polymerization conditions on the membrane properties was studied by adsorption analysis and membrane permeability. The PANI-coated polypropylene (PANI/PP) membranes possessed high affinity toward the proteins, which can be immobilized onto the membrane surface through physical adsorption or covalent immobilization. The quantity of immobilized horseradish peroxidase (HRP) and its activity depended on the quantity and quality (oxidation level) of PANI. The storage conditions for PANI/PP membranes containing immobilized HRP were studied. HRP immobilized on the PANI/PP membrane was shown to retain 70% of its activity after 3-month storage at +5°C, suggesting that this material can be used for practical application, such as in bioreactors as enzyme membranes
[Report to Chief J. E. Curry, by an unknown author #2]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
[Report to Chief J. E. Curry, by an unknown author #1]
No full textReport to Chief J. E. Curry, by an unknown author. The report contains a list of officers who gave depositions to the United States Attorney
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