105,818 research outputs found
Macrocyclization under kinetic control - a theoretical study and its application to the synthesis of macrocyclic poly(THIOLACTONES)
No full textA kinetic model for macrocyclization reactions of bifunctional chains undergoing simple and double ring closure reactions has been proposed. Numerical integration of the proper set of differential rate equations allows yields and distributions of cyclic oligomers to be calculated as a function of initial concentrations of reactants and effective molarities (EM(i)) of the rings being formed. In terms of computer time the present model is less demanding than analogous models previously published, in that a high degree of accuracy is obtained without taking into account explicitly linear oligomers with high polymerization degree. The model has been successfully applied to the synthesis of macrocyclic poly(thiolactones) via irreversible reaction of 2,2-dibutyl-1,2,3-dithiastannolane with glutaryl and pimeloyl chlorides. The best fits of the experimental oligomer distributions to the general equations gave the effective molarities from monomer to tetramer in both series
Survey of qualitative traits of European sea bass cultivated in different rearing systems
No full textThe purpose of this study was to evaluate the main qualitative traits of European sea bass fattened in farms adopting different rearing techniques (offshore cages, inshore cages, land-based basins) but fed the same diets in each production cycle, in a three year survey (2006, 2007, 2008). Three farms were chosen for each rearing technique and two sampling sessions of ten fish each were carried out for each rearing cycle. The proximate composition, the fatty acid profile and the cholesterol content were evaluated in the fillet of marketable size fish as well as the morpho-biometric parameters and the most important indices. Diets administered in 2008 had higher amounts of lipids, lower proportions of n-3 polyunsaturated fatty acids (PUFA) and higher proportions of n-6 PUFA compared to 2006 and 2007 diets. The chemical and fatty acid composition of the fish fillet was affected by the diet composition: fish fattened in 2008 exhibited statistically higher amounts of fat and cholesterol, lower proportions of n-3 PUFA and higher proportions of n-6 PUFA in comparison with fish cultivated in 2006 and 2007. Fish cultivated in cages, both offshore and inshore cages, exhibited leaner fillets, lower amounts of cholesterol and higher proportions of n-3 PUFA than fish cultivated in basins
On the aqueous acid catalyzed intramolecular aldol condensation of 3-(formylmethyl)cyclohexan-1-ones
No full textStudi sulla formazione diastereoselettiva dei 6-endo-idrossibiciclo[2.2.2]ottan-2-oni mediante condensazione aldolica intramolecolare di 3-(formilmetil)cicloesan-1-oni
No full textOn the Diastereoselectivity of the Aqueous-Acid-Catalized Intramolecular Aldol Condensation of 3-Oxocyclohexaneacetaldehydes."
No full textFatty acid profile and proximate composition of fillets from Engraulis encrasicholus, Mullus barbatus, Merluccius merluccius and Sarda sarda caught in Tyrrhenian, Adriatic and Ionian seas
No full textThis study examined the proximate composition, cholesterol content and fatty acid profile of fillet of the most important species captured in Italian seas and commonly consumed in the European Union, such as anchovy (Engraulis encrasicholus L.), red mullet (Mullus barbatus L.), European hake (Merluccius merluccius L.) and Atlantic bonito (Sarda sarda L.). The fish were caught in three different geographic areas of the Italian seas: south Tyrrhenian (ST), south Adriatic (SA) and Ionian (IO).
Anchovy from the ST sea had the highest lipid content (2.27%) compared to fish captured in the SA (1.81%) and IO seas (1.91%) (P < 0.01). Red mullet captured in the SA exhibited the highest amount of lipid content (7.54%) compared to fish from the ST (1.82%) and IO seas (3.23%) (P< 0.01). The total content of cholesterol of fish did not show significant differences from one geographic area to the other, particularly for European hake (from 98 to 66 mg/100 g).
The fatty acid profile of anchovy species was not affected by the geographic area of the fish catch. European hake caught in the ST sea showed the highest proportion of DHA (29.13%) in comparison with those captured in the SA (19.98%) and IO seas (19.84%). Atlantic bonito from the ST sea had the highest proportions of DHA (24.94%), compared to those from the SA (12.08%) and IO seas (13.83%). The SA bonitos contained a significantly lower proportion of EPA (3.31%) in comparison with fish from both the ST and IO seas (5.66 and 5.17% respectively). The red mullet captured in the ST sea exhibited the highest proportions of DHA, n-3 PUFA, total PUFA and significantly lower proportions of oleic acid and MUFA.
The fish coming from the ST sea showed better nutritional traits than those from other geographical areas although they all have excellent nutritional traits due to the low fat content and very high n-3 PUFA proportion
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
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
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Intercalibration exercise and fatty acid profile of two fish oil samples of different origin.
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