1,720,993 research outputs found
The outer membrane glycolipids of bacteria from cold environments: Isolation, characterization, and biological activity
No full textLipopolysaccharides (LPSs) are the main components of the external leaflet of the outer membrane of Gram-negative
bacteria. Microorganisms that colonize permanently or transiently cold habitats have evolved an array of structural
adaptations, some of which involve components of bacterial membranes. These adaptations assure the perfect
functionality of the membrane even at freezing or sub-freezing growth temperatures. This review summarizes the
state-of-the-art information concerning the structural features of the LPSs produced by cold-adapted bacteria. The LPS
structure has recently been elucidated from species mainly belonging to Gammaproteobacteria and Flavobacteriaceae.
Although the reported structural heterogeneity may arise from the phylogenetic diversity of the analyzed source strains,
some generalized trends can be deduced. For instance, it is clear that only a small portion of LPSs displays the O-chain. In
addition, the biological activity of the lipid A portion from several cold-adapted strains is reported
Controllo di qualità in vitro ed in vivo nella misura della massa ossea in differenti siti scheletrici
No full textO-specific polysaccharide structure isolated from the LPS of the Antarctic bacterium Pseudomonas ANT_J38B
No full textPseudomonas ANT_J38B is a Gram-negative bacterium isolated from an Antarctic island. LPS was extracted using the phenol/chloroform/petroleum ether method. A mild acid hydrolysis followed by a gel filtration purification afforded the O-chain. The polysaccharide was characterized by means of chemical analyses and NMR spectroscopy. The O-chain displays a disaccharide repeating unit with the following backbone: →4)-α-L-GulpNAc3OAcAN-(1 →3)-β-D-QuipNAc-(1→
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
Pectin Production from Tomato Seeds by Environment-friendly Extraction: Simulation and Discussion
Full text linkThe aim of this work is to model the extraction of pectin from tomato peels using different acids that could be more environmentally friendly. The AspenPlus® software is used to this end. Several cases, such as considering different extracting acids, the recycle of water and washing solvent streams are evaluated and compared. Tomato peels seasonally generated by factories in a local district, were considered as raw materials, as well as methanol and catalyst. Based on literature data and using Excel® worksheet, the mass and energy balances were set up for the extraction reactor and, hence, a pectin extraction yields up to 25 % and 17 %, for two different scenarios, was determined, while the washing and purification stages were simulated and optimized in AspenPlus®. The distillation tower for solvent recover was designed. The economic potential of these cases was calculated by considering utilities cost, product and by-product sales, wastewater treatment as well as raw material costs. Results show that tomato peels can be a feasible alternative for pectin production. Moreover, this work could be a basis for the development and design of a multi-product biorefinery based on tomato by-products produced by cannery industries in the frame of a circular economy approach
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
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