1,720,968 research outputs found
Use of the black soldier fly Hermetia illucens L. (Diptera: Stratiomyidae) as an alternative source of chitin and chitosan for the production of biopolymeric films in agro-food applications
Full text linkChitin and chitosan are natural polymer of great technological and economic interest, finding
several applications in many different fields. Chitin is a structural component of the exoskeleton
of arthropods and the fungal cell wall, while chitosan is its main deacetylated derivative.
Currently, chitin is industrially extracted from fishery waste, mainly crustacean shells. The
debate on the sustainability of this resource and the constant increase in market demand for
chitin and chitosan have driven the search for alternative sources. In this context, insects are
gaining great interest. In recent decades, large-scale insect breeding facilities for feed
production and organic waste disposal have arisen all over the world. These farms generate
large amounts of insect waste biomass (i.e., exuviae left over from moulting processes and dead
insects) rich in chitin that could be exploited as a source for the extraction of this polymer.
The aim of this work was to investigate different insect biomasses (larvae, pupal exuviae and
adults) generated from the farming of the dipteran Hermetia illucens (the most widely bred
species in Europe) as sources of chitin and chitosan. Chitosan was produced with the purpose
of being used for the production of coatings for the preservation of fresh fruits. From the three
different sources of H. illucens, chitin with characteristics and purity similar to that
commercially available from crustaceans was extracted. The highest yield (23%) was obtained
from pupal exuviae. From the analysis of the composition of the material obtained after each
step of the chitin extraction process, it was possible to calculate the efficiency of the extraction
methods applied, which were suitable for removing components extraneous to chitin from the
raw insect sample. The chitosan obtained from the deacetylation of chitin had some different
characteristics than commercial chitosan, particularly a very low viscosity and molecular
weight. This, together with the presence of impurities found in one sample, suggests the need
to modify the deacetylation process or some parameters of the chitin extraction method.
Chitosan produced from larvae, pupal exuviae and adults of H. illucens was used to produce
coating solutions that were applied to cherry tomatoes, strawberries, apricots and nectarines.
The preservative effect of the insect-derived chitosan coating was evaluated by investigating
changes occurred in the weight, pH, titratable acidity and total soluble solids content of fruits
during the storage period. Preliminary promising results were obtained from this investigation:
chitosan from H. illucens had similar or, in some cases, better effects than commercial chitosan;
often no different effects were observed in coated fruits than in uncoated fruits, but coating with
chitosan had better effects than coating with only solvent solution (a non-optimal formulation
of the solvent is hypothesised); chitosan obtained by homogeneous deacetylation always had
worse effects than heterogeneous chitosan; it was observed that bleaching treatment applied to
chitin may negatively affect the performance of the resulting chitosan. Furthermore, the
chitosan coating was particularly effective in reducing and delaying spontaneous mould growth
on the fruit during storage.
This work has therefore highlighted the potential of H. illucens as a source of chitin and chitosan
to be used in the agri-food sector as an alternative packaging. The results obtained are
encouraging, although further studies are needed to fully optimise the extraction processes of
these polymers in order to obtain the best characteristics for the desired applications
Proline enriched diet effects on haemolymph amino acid composition in Osmia bicornis (L.) females and males
No full textThirty years of research on nectar biology at the University of Siena – much more than a reward for insects
No full textThis article outlines the most significant stages of research on nectaries, nectar, and plant-pollinator relationships at the University of Siena. The initial research began in the mid-1990s, focusing on the structure-ultrastructure and functioning of nectaries for approximately a decade. Results from these studies revealed the peculiar organization and development of nectaries and highlighted and clarified the process of nectar resorption and its functions. Subsequently, research progressed to studies on the chemistry and biochemistry of nectar, ultimately aiming to understand how these aspects influence plant-pollinator relationships. This part of the research highlighted that specific nectar secondary metabolites affect pollinator behaviours that are important in the pollination process including pollinator mobility, time spent on a flower, memory and learning ability. The chemistry of gymnosperm pollination drop was also indagated opening interesting hypotheses on the evolution of these secretions and of insect pollination in angiosperms. Future research aims to better understand plant-pollinator interactions investigating pollination networks and the role of microorganisms inhabiting nectar. The diversity and complexity of plant-pollinator interactions, as well as the challenges related to their increasing degradation, are topics of dissemination to the local community of citizens thanks to specific projects developed in very recent years
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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