1,720,976 research outputs found
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
Insight into zeta potential measurements in biopolymer film preparation
No full textMicro- and nano-particle charge is one of the main factors
determining the physical stability of both emulsions and suspensions
and can be quantified by measuring their so called “zeta potential”.
When all the particles have a large either negative or positive zeta
potential value, they will repel each other and, as a consequence, the
suspension becomes stable. By contrast, whether the zeta potential is
close to 0 mV, the tendency for flocculation increases. Zeta potential
is, however, a feature of the particle in its environment and not of
the particle itself. In fact, its net charge in solution affects the ion
distribution surrounding the particle, thus resulting in an increase in
the concentration of counter-ions. The region over which this influence
extends is called “electrical double layer” (EDL) and EDL splits into
two regions (Figure 1). In the first, called “stern layer”, the ions are of
opposite charge with respect to the particles and, being strongly bound
to them, move with them. The second layer, conversely, is a “diffuse
layer” where the ions are less strongly attached and, inside it, there is
a boundary line between the ions moving with the particles and the
not moving ones. This region, called “slipping plane”, is known as the
surface of hydrodynamic shear and the potential existing in the slipping
plane is called zeta potential
Immobilization of two endoglucanases from different sources
Full text linkCellulases are a important family of
hydrolytic enzymes which catalyze the bond of cellulose
and other related cello-oligosaccharide derivates.
Industrial applications require enzymes highly stable and
economically viable in terms of reusability. These costs
can be reduced by immobilizing the cellulases, offering a
potential solution through enzyme recycling and easy
recovery. The covalent immobilization of enzymes is
reported here: one is commercial cellulase from
Aspergillus niger and other one is recombinant enzyme,
named CelStrep it because was isolated from a new
cellulolytic strain, Streptomyces sp. G12,. The optimal pH
for binding is 4.6 for both cellulases and the optimal
enzyme concentrations are 1 mg/mL and 5 mg/mL
respectively. The support for immobilization is a
poliacrylic matrix. Experiments carried out in this work
show positive results of enzyme immobilization in terms
of efficiency and stability and confirm the economic and
biotechnical advantages of enzyme immobilization for a
wide range of industrial applications
Enzymatic milk clotting activity in artichoke (Cynara scolymus) leaves and alpine thistle (Carduus defloratus) flowers. Immobilization of alpine thistle aspartic protease
No full textTwo different milk clotting enzymes, belonging to the aspartic protease family, were extracted from both artichoke leaves and alpine thistle flowers, and the latter was covalently immobilized by using a poly- acrylic support containing polar epoxy groups. Our findings showed that the alpine thistle aspartic pro- tease was successfully immobilized at pH 7.0 on Immobeads IB-150P beads and that, under these experimental conditions, an immobilization yield of about 68% and a recovery of about 54% were obtained. Since the enzyme showed an optimal pH of 5.0, a value very similar to the one generally used for milk clotting during cheese making, and exhibited a satisfactory stability over time, the use of such immobilized vegetable rennet for the production of novel dairy products is suggested
Polyamines as new cationic plasticizers for pectin-based edible films
No full textZeta potential and particle size were determined on pectin aqueous solutions as a function of pH and the effects of calcium ions, putrescine and spermidine on pectin film forming solutions and derived films were studied. Ca(2+) and polyamines were found to differently influence pectin zeta potential as well as thickness and mechanical and barrier properties of pectin films prepared at pH 7.5 either in the presence or absence of the plasticizer glycerol. In particular, Ca(2+) was found to increase film tensile strength and elongation at break only in the presence of glycerol and did not affect film thickness and permeability to both water vapor and CO2. Conversely, increasing polyamine concentrations progressively reduced film tensile strength and markedly enhanced film thickness, elongation at break and permeability to water vapor and CO2, both in the presence and absence of glycerol. Our findings indicate that polyamines give rise to a structural organization of the heteropolysaccharide different from that determined by calcium ions, previously described as "egg box" model, and suggest their possible application as plasticizers to produce pectin-based "bioplastics" with different features
Fresh-cut fruit and vegetable coatings by transglutaminase-crosslinked whey protein/pectin edible films
No full textFresh cut apples, potatoes and carrots were coated by a blended whey protein/pectin film, prepared in the presence of transglutaminase, and several properties of the coated and uncoated fruit and vegetable samples were analyzed during their storage. The linear increase in apple weight loss observed during storage was significantly reduced after 10 days when the samples were coated by whey or soy protein isolate films (about 20 and 40%, respectively) but mostly (about 80%) by whey protein film grafted with pectin and transglutaminase. In addition, the latter film was able to totally prevent the weight loss of potato and carrot samples at least until the 6th day of sample storage. Coating by the crosslinked blended film prevented microbial growth in all samples analyzed, also preserving their phenolic content and carotenoid in carrots. Finally, a marked reduction of both hardness and chewiness, detected after ten days of storage in all the uncoated samples by a texture profile analysis, was shown to be effectively counteracted by coating, whereas no significant differences in the acceptability scores of the coated samples after storage, were recorded by a sensory panel with respect to all samples tested before storage
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
Application of Transglutaminase-Crosslinked Whey Protein/Pectin Films as Water Barrier Coatings in Fried and Baked Foods
No full textWhey protein/pectin edible films were prepared in the presence of transglutaminase and tested as water barrier coatings of both fried doughnuts and french fries as well as of baked food like “taralli” biscuits. Our results demonstrated an undoubted effect of the produced hydrocolloidal films, known to markedly reduce water vapor permeability, in decreasing moisture loss in both doughnuts and french fries when applied before food frying. At the same time, a significant decrease in oil content was observed in the coated fried foods (about 50 % in doughnuts and 25 % in french fries) with respect to both uncoated controls and whey/soy protein-coated samples. No difference was observed between uncoated and coated both doughnuts and french fries with regard to their texture properties and as confirmed by the data from sensory evaluation tests. Furthermore, since the coating by edible films endowed with low water vapor permeability could be useful to prevent moisture absorption by baked foods, we tested the whey protein/pectin film prepared in the presence of transglutaminase, which was also used to coat taralli biscuits. The proposed methodology resulted to be effective to hinder moisture absorption by biscuits during a long storage period, keeping water content constant from 0 to 50 days, thus preventing the food matrix conversion from a glassy state to a rubbery state which is the major cause of baked food rejection by consumers
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