5,136 research outputs found
Plant extracts as biocontrol agents against Aspergillus carbonarius growth and ochratoxin A production in grapes
Aspergillus carbonarius (Bainier) Thom. is an important pathogen and ochratoxin A (OTA) producer in grapes that
can be controlled by adopting sustainable approaches. Here we evaluate the application of natural plant extracts
as an alternative to synthetic fungicides to reduce OTA contamination and to prevent infection of grapes by two
isolates of A. carbonarius. In a preliminary screening, natural extracts of chestnut flower, cistus, eucalyptus,
fennel, and orange peel were evaluated for their antifungal and anti-mycotoxigenic efficiency in a grape-based
medium at concentrations of 10 and 20 mg/mL. Cistus and orange peel extracts demonstrated the best anti-
fungal activity at both concentrations. Although the eucalyptus extract demonstrated no significant effect on
Aspergillus vegetative growth, it significantly reduced OTA by up to 85.75 % at 10 mg/mL compared to the
control. Chestnut flower, cistus, eucalyptus, and orange peel extracts were then tested at the lowest concen-
tration (10 mg/mL) for their antifungal activity in artificially inoculated grape berries. The cistus and orange peel
extracts demonstrated the greatest antifungal activity and significantly reduced mold symptoms in grapes.
Moreover, all tested natural extracts were able to reduce OTA content in grape berries (17.7 ± 8.3 % - 82.3 ±
3.85 % inhibition), although not always significantly. Eucalyptus extract was particularly efficient, inhibiting
OTA production by both strains of A. carbonarius by up to >80 % with no effects on fungal growth. The use of
natural eucalyptus extract represents a feasible strategy to reduce OTA formation without disrupting fungal
growth, apparently maintaining the natural microbial balance, while cistus and orange peel extracts appear
promising as inhibitors of A. carbonarius mycelial growth. Our findings suggest that plant extracts may be useful
sources of bioactive chemicals for preventing A. carbonarius contamination and OTA production. Nonetheless, it
will be necessary to evaluate their effect on the organoleptic properties of the grapes.This work was supported by the Foundation for Science and Tech-
nology (FCT, Portugal) #1 under Grant from national funds FCT/MCTES
(PIDDAC) to CIMO [number UIDB/00690/2020 and UIDP/00690/
2020] and SusTEC [number LA/P/0007/2020]; the European Regional
Development Fund (ERDF) through the Competitiveness and Interna-
tionalization Operational Program (CIOP) #2 under Grant dedicated to
the project “PreVineGrape - Development of a biofungicide to combat
grapevine diseases [number POCI-01-0247-FEDER-049695].info:eu-repo/semantics/publishedVersio
Ecophysiology of Penicillium expansum and patulin production in synthetic and olive-based media
Olives and their derivatives, in particular olive oil, represent one of the most significant agricultural products in the Mediterranean basin. Storage under inadequate conditions poses serious problems concerning fungal contamination, with consequent defects and potential mycotoxin production in olives and olive oils. Penicillium expansum represents one of the most significant postharvest pathogens in several fruits, including olives. Not only it causes blue mold but also is one of the most relevant patulin producing species of the genus Penicillium. The aim of this research was to evaluate the ecophysiological conditions governing growth and PAT production by P. expansum strains previously isolated from Tunisian olives. For this purpose, four P. expansum isolates were tested in a synthetic medium (Czapek Yeast Autolysate, CYA) and in olive-based medium (OM) for their ability to grow and produce PAT under different temperatures (4 °C, 15 °C and 25 °C) for 10 and 20 d. The mycotoxin was analysed by HPLC-UV. Results showed that all isolates were able to grow on tested media at different temperatures. Different PAT production profiles were found, showing that at 25 °C P. expansum isolates were able to produce PAT on CYA and OM medium. At 15 °C the production of PAT was only detected on CYA medium, while no PAT production was detected at 4 °C for the two media.The authors are grateful to the Foundation for Science and
Technology (FCT, Portugal) and FEDER under Programme PT2020
for financial support to CIMO (UID/AGR/00690/2019).info:eu-repo/semantics/publishedVersio
Exploratory study on maturation and competition level in young karate practitioners
Emparelhar crianças propicia sucesso e reduz lesões no desporto. Apesar das diferenças de maturação entre
crianças, a idade cronológica mantém-se o principal critério para equalizar os níveis de competição, mas com
uma eficiência limitada. No entanto, no karaté, o peso também é considerado. Fomos verificar se existe associação entre a idade cronológica e os indicadores maturacionais e, encontrar modelos simples que permitam colocar em reflexão novas formas de avaliação da maturação. Foram recolhidos dados em 54 jovens
praticantes de karaté (idade: 12,67 ± 2,49 anos; experiência: 4,99 ± 2,44 anos; altura: 150,45 ± 15,25cm; peso: 43,09 ± 14,17 kg, 20 raparigas). A idade correlacionou-se significativamente com auto-observação da maturação sexual (rho = 0,838; p < 0,01), e foi possível encontrar modelos de regressão simples que têm uma
explicação moderada na maturação, apenas utilizando variáveis de medição simples, tal como a altura, o peso e o perímetro do braço. Estes resultados devem levar as entidades competentes a refletir acerca do modo de
emparelhamento dos atletas nas competições de uma forma justa em termos de maturação.Paring children improve the chance for success and reduce injury in sport. Despite the maturity differences between children, chronological age remains the main criterion to equalize competition levels, but with limited efficiency. However, in Karate, weight is also considered. We went to investigate the association between chronological age and maturational indicators and find simple models to put on reflection new ways to assess the maturity. Data were collected in 54 young Karate practitioners (age: 12.67 ± 2.49 years, experience: 4.99 ± 2.44 years, height: 150.45 ± 15.25 cm, weight: 43.09 ± 14, 17 kg, 20 girls). Age correlated significantly with self-observation of sexual maturation (rho = 0.838; p < 0.01), and it was possible to find simple regression models that have a moderate explanation in maturation, using only simple measurable variables such as the height, weight and arm circumference. These results should lead the competent entities to reflect on the way of pairing of the athletes in the competitions, in a fair way in terms of maturation.info:eu-repo/semantics/publishedVersio
Effect of a static non-uniform magnetic field on the surface properties of acrylic resin
INTRODUCTION: The acrylic resin is a polymeric material with several applications in different
scientific and technological fields, especially in medicine and biotechnology. Its physical characteristics or
their possible modifications can imply new ways of utilization and applicability.
OBJECTIVE: To study the effect of a magnetic field on the surface physico-chemical properties usually
implied in bacterial adhesion, especially surface hydrophobicity.
METHODS: the hydrophobicity of the resin surface was determined by sessile drop contact angle
measurements, using van Oss (1994) methodology. Accordingly, a substance (i) is considered hydrophobic
when the variation of the free energy of interaction between two entities of substance (i) immersed in water
is negative (DGiwi<0). That is to say, the two entities of substance (i) interact preferentially between them
then with water. On the contrary, if DGiwi>0, substance (i) is hydrophilic.
Two types of resin samples were used: hydrated and non-hydrated ones. The hydrated samples were
obtained by autoclaving at 121ºC. Before contact angle measurements, the samples submitted to the
magnetic field were exposed during 24 hours to a field of 500gauss generated between to parallel magnetite
plates.
RESULTS AND DISCUSSION: The principal results are summarized in Table 1. As could be expected
the hydrated resin is hydrophilic, while the dehydrated is hydrophobic. However, when the hydrated resin is
submitted to the magnetic field it becomes even more hydrophobic than when dehydrated. This can be
explained by the effect of the magnetic field on the orientation of the water molecules of hydration.
Consequently, there is an evident alteration of surface properties promoted by the magnetic field
Root cause analysis of low throughput situations using boosting algorithms and the TreeShap analysis
Detecting and diagnosing the root cause of failures in mobile networks is an increasingly demanding and time consuming task, given its technological growing complexity. This paper focuses on predicting and diagnosing low User Downlink (DL) Average Throughput situations, using supervised learning and the Tree Shapley Additive Explanations (SHAP) method. To fulfill this objective, Boosting classification models are used to predict a failure/non-failure binary label. The influence of each counter on the overall model’s predictive performance is performed based on the TreeSHAP method. From the implemen tation of this technique, it is possible to identify the main causes of low throughput, based on the analysis of the most critical counters in fault detection. Furthermore, from the identification of these counters, it is possible to define a system for diagnosing the most probable throughput degradation cause. The described methodology allowed not only to identify and quantify low throughput situations in a live network due to the occurrence of misadjusted configuration parameters, radio problems and network capacity problems, but also to outline a process for solving them.info:eu-repo/semantics/publishedVersio
Pretreatments applied to microalgae residues to enhance anaerobic digestion
ABSTRACT: Biomass of microalga Chlorella protothecoides, grown under autotrophic and heterotrophic
conditions and subjected to pretreatments, were energetically valorized through anaerobic digestion process according to the substrates: autotrophic algae (A), heterotrophic algae (H), heterotrophic algae extracted (HE), autoclave pretreated heterotrophic algae (HPA), enzyme pretreated heterotrophic algae (HPE), ultrasound pretreated heterotrophic algae (HPU), and inoculum (I). Despite the application of pretreatments, the highest methane production was obtained in the algae extracted digestion with 172 mL CH4, against 153, 126 and 142 mL obtained in HPA, HPE and HPU, respectively. The COD removal capacity was higher in the HPA sample while the TS and VS removal reached higher values in the autotrophic alga.N/
A consistent scalar-tensor cosmology for inflation, dark energy and the Hubble parameter
The authors are grateful for financial support to the Cruickshank Trust (CW), EPSRC/GG-Top (CW, JR), Omani Government (MA), Science Without Borders programme, CNPq, Brazil (DR), and STFC/CfFP (CW, AM, RB, JM). CW and AM acknowledge the hospitality of CERN, where this work was started. The University of Aberdeen and University of Edinburgh are charitable bodies registered in Scotland, with respective registration numbers SC013683 and SC005336.Peer reviewedPostprin
Candida albicans enhanced phospholipase production after exposition to a static non-uniform magnetic field
INTRODUCTION: Microbial virulence factors are responsible for tissue damage in hosts. Candida
albicans is an opportunistic pathogen that constitutes an increasing risk of infection, especially for
immunosuppressed or immunocompromised patients.
OBJECTIVE: The objective of this study was to determine the effect of a static non-uniform magnetic
field on the phenotype expression of different strains of Candida albicans.
METHODS: The strains of Candida albicans were grown on phospholipase-agar, according to Shimizu et
al. (1996) and incubated at 37 ºC inside a magnetic field (except the assays used as blank). The magnetic
field was generated by two magnetite plates (Figure 1) and standardized as a function of distance versus
number of magnetic plates (Figure 2). The magnetic field was of 500 gauss in the central part between the
two magnetic plates.
RESULTS: The preliminary results show a visible increase in the halo formed due to phospholipase
production, suggesting that the exposition to a magnetic field can enhance the expression of this virulence
factor
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