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Elucidat ion of type of molecular interactions for the imprinting of shikimic acid
No full textDuring the preparation of shikimic acid imprinted polymer, the effect of rebinding solution water
content on the rebinding performance of shikimic acid (SA) imprinted polymer was studied. Result
showed that the highest affinity toward SA was in a 100% aqueous rebinding solution, suggesting
that the interactions occurred between SA and the polymer were ionic and/or hydrophobic in
nature. Further study on the effect of rebinding solution pH to the SA imprinted polymer rebinding
performance showed that the performance of the SA imprinted polymer depended on the rebinding
solution pH and the highest affinity occurred at pH 4.0this confirmed that ionic interaction
played an important role in the rebinding of SA. Taking into account the deductions made from
the combined results of the rebinding solution water content and effect of pH, together with
observation of the red shift in the SA spectral during ultraviolet-visible spectroscopic titration
experiments, suggest that the specificity shown by SA imprinted polymer in the aqueous solution
was due to both ionic and ??? hydrophobic interactions
Organizational Variables, Job Variables, And Job Stress: The Moderating Effect Of Personality Among Paiddealers Within The Stock Broking Firms In Penang
Get PDFThe purpose of this study is to determine whether organizational variables (formalization, centralization, and organizational climate) and job variables (role conflict, role ambiguity, and role overload) affect job stress. Additionally, two personality variables (Type A personality and self-efficacy) were examined whether they serve to moderate the relationship between the independent variables and the dependent variable
Preparation and evaluation of aqueous phase compatible molecularly imprinted polymers for shikimic acid
Get PDFShikimic acid (SA) is an important component in the production of several important
drugs particularly the anti-influenza drug, Oseltamivir. Naturally, SA exists as an
intermediate in the plant biosynthesis of aromatic compounds via shikimate pathway.
Commercially, SA is extracted from the Chinese star anise or produced through the
fermentation process by modified strain of Escherichia coli (E. coli). Regardless of the
method of production, SA needs to be purified before it can be used for the intended
purpose. Conventional method in the purification of SA usually involved the use of
non-specific adsorbents that are less effective in isolating the SA. Molecularly
imprinted polymer (MIP) being one of the latest adsorbents in separation science,
offers an alternative technique that is more selective and specific than the conventional
adsorption methods.
MIP is known to be not compatible to the aqueous phase with usually low or no
selectivity, making the preparation of MIP that work well in aqueous phase a challenge
to those in the field. Reported in this thesis are exploratory work carried out to prepare
non-covalent imprinted polymer for SA with the aim that the polymer prepared is
capable of working in highly aqueous environment in which the raw extract of SA is
usually in.
“Trial and error” approach was used as the preliminary tool in searching the right
formulation of template:monomer:cross-linker (TMX) ratio that produced a good
imprinted polymer judging from the imprinting factor (IF) scores of the polymer in
batch rebinding experiments. The optimized TMX ratio finally determined was 1:6:10 in 10 mL methanol and water (4:1, v/v) porogen system. The best template: monomer
(TM) ratio was also evaluated using ultraviolet (UV) spectroscopy approach, the
results obtained were in agreement with the preliminary “trial and error” results,
indicated that TM ratio of 1:6 was the optimal.
The polymer was physically characterized using Fourier transform infrared (FTIR)
spectroscopy and scanning electron microscopy (SEM) techniques. Results indicated
that complete polymerization was achieved and different morphologies observed
between imprinted and control polymers may be used to explain the imprinting effect
shown by the SA imprinted polymer. Optimization on the rebinding conditions
suggested that the SA imprinted polymer performed best in 100% aqueous
environment at pH 4.0.
Binding isotherm study suggested that the binding sites distribution was heterogeneous
in nature and it can be well described using Freundlich isotherm model. Study of the
polymer’s adsorption kinetic concluded that the adsorption process obeyed pseudo
second order kinetic with rate constant, K of 0.0047 gmg-1min and the experimental
maximum adsorption for SA imprinted polymer was determined as 38.8 mgg-1.
Cross-reactivity experiments results showed that the imprinted polymer having good
selectivity toward SA and the polymer was packed into cartridge and used for the
separation of SA from artificial mixture of SA, methyl shikimate (SE) and gallic acid
(GA) in tap water. A clean separation with three isolated peaks as shown in high
performance liquid chromatography (HPLC) chromatogram was obtained
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
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