1,721,097 research outputs found
Methodologies for extraction, isolation, characterisation, and quantification of bioactive compounds.
No full textSince it is widely recognized that the beneficial influence of fruit on human health is linked with the presence of specific phytochemicals, determining the nature of these compounds in different commodities, and the influence of preharvest, postharvest and processing treatments, have been major areas ofresearch (Espin et al., 2007; Frankel, 2007). Antioxidants can be measured as individual compounds or as a total capacity, yet some methods used to quantify total antioxidant activity are thought to take into account compounds not classed as antioxidants, for instance, reducing sugars (Huang et al., 2005). This chapter summarizes the wide variety of extraction and characterization techniques used to quantify individual or total antioxidants, as well as other bioactive compounds.Fil: Cools, Katherine. University Of Cranfield; Reino UnidoFil: Vicente, Ariel Roberto. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; Argentina. University Of Cranfield; Reino UnidoFil: Terry, Leon. University Of Cranfield; Reino Unid
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Identification of volatile organic compounds (vocs) as biomarkers of potato rots during cold storage and ecophysiological study of the pathogens involved.
Get PDFPotato tubers are stored for up to ten months. Therefore, controlling the
conditions (temperature and relative humidity) in the storage environment is
essential to reduce the risk of appearance of potato diseases. Fluctuations in the
environmental conditions appear throughout the storage room, allowing the
development of potato rots. This work aimed to identify Volatile Organic
Compound (VOC) biomarkers of potato diseases to achieve an early
identification of potato rots under commercial storage conditions. Furthermore, to
achieve a deep understanding of the ecophysiology of the fungal and bacterial
pathogens involved. Some of the objectives of this study were the isolation of
fungal pathogens from potato tubers, the study of the mycotoxin production in the
presence of dry rot, the development of a methodology for the VOC sampling and
identification, and the study of the effect of storage time on the potato
susceptibility to dry rot and soft rot.
A method for the untargeted detection and identification of VOCs produced by
potatoes during storage was developed using Thermal Desorption-Gas
Chromatography-Time of Flight- Mass Spectrometry. A range of different TD
(Thermal desorption) tubes were evaluated, and the most suitable for the
adsorption of VOCs under the study conditions were selected.
An in vitro study of the pathogens responsible for gangrene and dry rot was
carried out using Natural Potato Dextrose Agar (PDA) and three different
temperatures (5,10 and 15ᴼC) and water activities (aw) (0.97, 0.98, 0.99). Higher
temperature and aw resulted in higher growth rate and lag time of both pathogens,
Fusarium spp. and Boeremia foveata. Furthermore, mycotoxins, such as T-2, HT-
2, diacetoxyscirpenol, beauvericin and neosolaniol, were detected in potato
tubers infected with dry rot.
An in vivo study of dry rot and soft rot was carried out at 8.5ᴼC, using two cultivars
with different susceptibility to these diseases (cvs. Record and Casablanca). The
internal and external lesions resulting from the infection were assessed over time
and the VOC fingerprint of each cultivar at each time point was determined. The
effect of storage time on the disease severity was also evaluated, demonstrating
that at 8.5ᴼC, only dry rot’s severity was affected by the longer storage time, while
no effect was observed in soft rot.
Several VOCs were detected in higher abundance in presence of the pathogen
in the in vivo and in vitro studies. They were selected as potential biomarkers of
dry rot, soft rot and gangrene. Ethanol, acetone, ethyl acetate and acetic acid
were detected in vitro as potential indicators of the presence of a fungal or
bacterial disease. Furthermore, 2-methylpropan-1-ol was selected as a potential
indicator of the presence of a fungal pathogen, such as Fusarium spp.,
responsible for dry rot in potato tubers. In vivo, 1-methoxy-3-methylbutane, 2-
butanone, dimethyl disulfide and hydrogen cyanide were detected as potential
biomarkers of dry rot or soft rot in potato tubers.
Lastly, based on the findings that have been achieved in this work, future
research should be focused on the study of the growth and VOC production of
Pectobacterium carotovorum spp. in vitro and the study of the disease severity
and VOC production of gangrene in vivo. Furthermore, a validation of the VOC
results achieved in this work under commercial storage conditions should be
carried out. These studies will confirm and enhance the findings achieved in this
work.Kourmpetli, Sofia (Associate)
Terry, Leon A. (Associate)PhD in Environment and Agrifoo
Chemical diversity of Moroccan medicinal and aromatic plants and their potential for agricultural bioproducts
No full textTerry, Leon A. - Associate Supervisor
Beale, Mike H. - Associate Supervisor
Sobeh, Mansour - Associate SupervisorBiostimulants and bioprotectants (bioproducts) have been recognised as potential
alternatives to synthetic agrochemicals, or as substances that could enhance their use
efficiency. Extracts from medicinal and aromatic plants, and their constituent secondary
metabolites are major sources of bioproducts. In arid areas of Morocco, medicinal and
aromatic plants are abundant and potentially contain rich and unique metabolites, but
they have not been widely assessed for their chemical composition as well as
biostimulant and bioprotectant potential.
In this work, phytochemical profiling of nine medicinal and aromatic plants from
Morocco was undertaken. The first report on the chemical profile of Vachellia
gummifera including the distribution of metabolites between its leaves and stems is
presented. Additionally, this work presents arguably the most comprehensive report on
the chemical profile of polar extracts from Ammodaucus leucotrichus that includes five
previously undescribed compounds comprising two terpenoids and three lignans, in
addition to 39 compounds that are reported from the plant for the first time. The novel
compound, 8-(1H-indol-3-yl-methyl)rutin, which is a methylene bridged 1H-indole-
flavonoid glycoside conjugate is also reported from the polar leaf extract of Capparis
spinosa.
Biostimulant assessments using a seed soaking treatment revealed only minor positive
effects as most polar extracts showed no significant stimulation of wheat growth.
Significant phytotoxicity was however shown with extracts of Peganum harmala and C.
spinosa. These inhibited the emergence and growth of wheat seedlings, with more
potent activity being observed with C. spinosa. This phytotoxicity could be beneficially
exploited in the development of bioherbicides. Bioprotectant assessments through
antifungal tests on pathogens relevant to major African crops did not produce any
significant results for extracts of all the plant species. The link between chemical
profiling and bioactivity, the beneficial exploitation of phytotoxicity, and the key
challenges for implementing bioactive extracts on a large scale are discussed.PhD in Environment and Agrifoo
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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