1,720,959 research outputs found
N-linked peptidoresorc[4]arene-based receptors designed for protein surface recognition. NMR analysis of Italian virgin olive oils and structural analysis of polysaccharides.
Full text linkThe first part of this work concerned the synthesis of N-linked peptideresorcarenes and the study of their surface interaction with enzymes. As known, an important class of protein surface receptors based on the attachment of four cyclic peptides to a calix[4]arene scaffold was developed by Hamilton and targeted to the serine protease α-chymotrypsin (ChT). Moving from Hamilton’s results and from some preliminary molecular modeling studies, valyl-leucine, leucyl-valine and valyl-aspartic peptidoresorc[4]arenes have been designed with the aim to target the predominantly cationic region surrounding the active site of ChT. By varying sequence, nature, and stereochemistry of the side chains, we prepared anionically functionalized N-linked peptidoresorc[4]arenes by hydrogenation of their precursor benzyl esters. From this family of receptors we have identified noncompetitive inhibitors of ChT, which function by binding to the surface of the enzyme in the neighborhood of the active site cleft (Ki values ranging from 13 to 0.8 µM).
The second topic of the work was the NMR characterization of the Italian virgin olive oils from the harvesting seasons 2009/10, 2010/11.
Following the experimental protocol established in the Annalaura Segre NMR Laboratory (CMI, CNR in Montelibretti, Rome), based on 1H-NMR and statistical multivariate analysis of the data (ANOVA, PCA and LDA), nearly 300 Italian virgin olive oil samples, produced in two harvesting years, 2009/10 and 2010/11, by certified chains in different italian regions have been studied.
The NMR results confirm that the chemical composition of olive oils, with regards to minor components, is influenced by geographical, ecological and genetic factors and depends also on the harvesting year.
We could also identify some oil components that remain stable in different harvesting years, representing seasonal-independent characteristics of the oil produced in each region.
A contemporary investigation, carried out at CNR, was focused on structural analysis of polysaccharides. Specificaly, we performed NMR characterization of a carboxy-methyl derivative of scleroglucan, a polysaccharide produced by fungi of the Sclerotium genus, to identify the position involved in the carboxymethylation; furthermore, a preliminary structural study has been performed on a set of polysaccharides obtained from the cultures of Hericium erinaceus, with the aim of identifying the configuration and the connections between the monosaccharidic units
Molecular recognition of natural products by resorc[4]arene receptors
No full textThis review is aimed at providing an overview of the up-to-now published literature on resorc[4]arene macrocycles exploited as artificial receptors for the molecular recognition of some classes of natural products. A concise illustration of the main synthetic strategies developed to afford the resorc[4]arene scaffold is followed by a report on the principles of the gas-phase investigation of recognition phenomena by mass spectrometry (MS). Emphasis is placed on gas-phase studies of diastereoisomeric complexes generated inside a Fourier transform-ion cyclotron resonance (FT-ICR) mass spectrometer by resorc[4]arene receptors towards a series of natural products, namely amino acids, amphetamine, ethanolamine neurotransmitters, dipeptides, vinca alkaloids and nucleosides. The literature outcomes discussed here, taken largely from our own revisited work, have been completed by references to other studies, in order to draw a broader picture of this rapidly evolving field of research
NMR Characterization of Carboxymethyl Scleroglucan
No full textHigh field NMR characterization of carboxymethyl scleroglucan (Scl-CM) recently synthesized through reaction of the native polymer (Scl) with chloroacetic acid in basic conditions is discussed, reporting the position of the carboxymethyl groups in the scleroglucan moiety. The comparison between the Scl-CM and the Scl structures can be useful to comprehend their different profiles in the viscosity-shear rate curves and their different ability to form physical gels
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
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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