1,720,973 research outputs found
Chemoenzymatic Synthesis of Alkyl Glycoside Fatty Acid Esters and Investigation of their Emulsifying Properties
No full textSugar fatty acid esters (SFAEs) are non-ionic surfactants that are characterized by excellent surface and interfacial tension reduction capability, low toxicity, and biodegradability. These features make SFAEs extremely promising for industrial applications as emulsifiers in the cosmetic and food sectors.[1] Interestingly, SFAEs can be obtained from renewable resources (from industrial waste and biomass) by enzymatic and/or chemoenzymatic approaches, thus answering the need for evermore sustainable and circular chemistry.[2,3]
6-O-Lauroyl-, 6-O-palmitoyl- and 6-O-stearoyl-1-O-butyl glucopyranosides were enzymatically synthesized by reacting n-butyl glucoside with molten fatty acids in an easily scalable solvent-free system. Derivatization of glucose as an alkyl glucoside before the esterification reaction played a key role to circumvent the striking different solubility of glucose and fatty acids. The physico-chemical properties of these tensides, such as interfacial tension features, W/O emulsification capability and W/O stability over time were deeply investigated.[4]
References
1. N.S. Neta, J.A. Teixeira, L.R. Rodrigues, Crit. Rev. Food Sci. Nutr. 2015, 5, 595.
2. A.R. Alcántara, P. Domínguez de María, J.A. Littlechild, M. Schürmann, R.A. Sheldon, R. Wohlgemuth, ChemSusChem 2022, e202102709.
3. T. Keijer, Nat. Chem. 2019, 11, 190.
4. S. Sangiorgio, E. Pargoletti, M. Rabuffetti, M.S. Robescu, R. Semproli, D. Ubiali, G. Cappelletti, G. Speranza, under review
This work was financially supported by Cariplo Foundation (Italy) (call: “Circular Economy for a sustainable future 2020”, project BioSurf, ID 2020-1094)
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
A two-step enzymatic approach to cheese whey valorization: Synthesis of alkyl galactoside fatty acid esters as non-ionic biosurfactants
No full textCheese whey is the main wastestream of dairy industry. After protein recovery, the resulting whey permeate
contains a pool of carbohydrates (lactose as well as its hydrolysis products, i.e. glucose and galactose) that
can be exploited as feedstock for the synthesis of Sugar Fatty Acid Esters (SFAE), non-ionic surfactants
characterized by emulsifying, stabilizing, and detergency properties.1
In this work,2 an immobilization study of β-galactosidase from Aspergillus oryzae (GalAo) was carried out with
the aim to develop a robust biocatalyst for lactose upcycling. Several types of binding chemistry, chemical
activation of the support, and immobilization conditions were assayed. Glyoxyl-Sepabeads EC-EP resulted in
good immobilization yields (immobilized protein=65% and immobilized activity=58%) and moderate activity
recovery (20%). The immobilized GalAo was used for the synthesis of a library of alkyl-β-D-galactosides by
reacting lactose with naturally occurring alcohols 2a-2g through a transglycosylation reaction; compounds
(3a-3g) were isolated in moderate to good yields (20-45%) (Scheme 1A). n-Butyl β-D-galactopyranoside (3d)
was submitted to the esterification step with palmitic acid in a solvent-free system by using Novozym 435 as
the biocatalyst,3 affording 6-O-palmitoyl-1-O-butyl galactopyranoside (4d) (Scheme 1B).
Scheme 1. A) Transglycosylation of lactose (1) with natural aliphatic alcohols (2a-g) catalyzed by immobilized GalAo in buffer pH
4.3/alcohol/(acetone), r.t., 6 h. B) Esterification of 3d with palmitic acid catalyzed by Novozym 435 in a solvent-free system, 80 °C, 8
h, molecular sieves. n.o.=not optimized.
Interfacial features and W/O emulsifying properties of 4d together with W/O emulsion stability over time
were evaluated.
Acknowledgements
This work was financially supported by Cariplo Foundation (Italy) (call: “Circular Economy for a sustainable future 2020”,
project BioSurf, ID 2020-1094).
References
1. Ortiz, M.S.; Alvarado, J.G.; Zambrano, F.; Marquez, R. J. Surfact. Deter. 2022, 25, 147-183.
2. Semproli, R. et al., manuscript in preparation
3. Sangiorgio, S.; Pargoletti, E.; Rabuffetti, M.; Robescu, M.S.; Semproli, R.; Ubiali, D.; Cappelletti, G.;
Speranza, G. Colloids Interface Sci. Commun. 2022, 48 100630
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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