106 research outputs found
The filamentous fungi culture collection of the Department of Food Science (CCDCA), Federal University of Lavras, Brazil
Brazil has one of the highest levels of biological diversity due to its large geographical
area, high coverage by rainforests, and endemic biomes, such as the
Brazilian Atlantic Forest, Cerrado and Caatinga. Of the estimated 1.5 million
species of fungi only 5% are known. Much of this unknown biodiversity is in the
tropics, which is seriously threatened by some agricultural activities, reinforcing
the urgent need for biodiversity studies in these areas. The maintenance
and preservation of fungal cultures are important elements for such a requirment.
The establishment of a culture collection of filamentous fungi in the
Mycotoxins and Mycology Laboratory, Department of Food Science (CCDCA),
Federal University of Lavras (UFLA) commenced from the bases of species
maintenance, taxonomy, biotechnology and toxigenicity. The laboratory was established
in 2007 to preserve potentially mycotoxigenic fungi, especially ochratoxin
A and aflatoxins producers, which were isolated from food. Currently the
CCDCA has more than 1000 isolates of Aspergillus, Penicillium, Cladosporium,
Fusarium, Alternaria, Chaetomium, Mucor, Eurotium, and Neosartorya. A total
of 66 species are represented which were isolated from food, cave environments,
and soils of the Brazilian Atlantic Forest, Cerrado and Caatinga. A total of 328
cultures are preserved and maintained by periodic subculture, 137 by mineral
oil preservation, and 550 by filter paper preservation. The staff trains graduate
students in the taxonomy of major taxa of importance to agricultural research
and food science. Finally, the CCDCA and UFLA, Brazil, in collaboration with
the IBB-Biological Engineering Centre, Micoteca da Universidade do Minho,
Portugal, intend to develop a project on polyphasic studies of Aspergillus and
Penicillium isolated from various substrates, sources, and environments in Brazil.
To pursue this aim CCDCA intends to: a) preserve Aspergillus and Penicillium
strains for comparative studies between Brazilian regions and worldwide;
b) foster the study of Aspergillus and Penicillium for biotechnological and toxigenic
potential, and training in identification, preservation and distribution;
c) establish quality control of fungal assays; and d) establish the CCDCA as
a member of the global network of culture collections and participate in the
international forums and organisations related to culture collections
Correlated Mixture Between Adiabatic and Isocurvature Fluctuations and Recent CMB Observations
This work presents a reduced chi^2_nu test to search for non-gaussian signals
in the CMBR TT power spectrum of recent CMBR data, WMAP, ACBAR and CBI data
sets, assuming a mixed density field including adiabatic and isocurvature
fluctuations. We assume a skew positive mixed model with adiabatic inflation
perturbations plus additional isocurvature perturbations possibly produced by
topological defects. The joint probability distribution used in this context is
a weighted combination of Gaussian and non-Gaussian random fields. Results from
simulations of CMBR temperature for the mixed field show a distinct signature
in CMB power spectrum for very small deviations (~ 0.1%) from a pure Gaussian
field, and can be used as a direct test for the nature of primordial
fluctuations. A reduced chi^2_nu test applied on the most recent CMBR
observations reveals that an isocurvature fluctuations field is not ruled out
and indeed permits a very good description for a flat geometry Lambda-CDM
universe, chi^2_930 ~ 1.5, rather than the simple inflationary standard model
with chi^2_930 ~ 2.3. This result may looks is particular discrepant with the
reduced chi^2 of 1.07 obtained with the same model in Spergel et al. (2003) for
temperature only, however, our work is restricted to a region of the parameter
space that does not include the best fit model for TT only of Spergel et al.
(2003).Comment: Accepted for publication in Physical Review
Evaluation of antifungal activity of essential oils against potentially mycotoxigenic Aspergillus flavus and Aspergillus parasiticus
The antifungal activity of essential oils of fennel (Foeniculum vulgare Mill., Apiaceae), ginger (Zingiber officinale Roscoe, Zingiberaceae), mint (Mentha piperita L., Lamiaceae) and thyme (Thymus vulgaris L., Lamiaceae) was evaluated against mycotoxin producers Aspergillus flavus and A. parasiticus. High Resolution Gas Chromatography was applied to analyze chemical constituents of essential oils. The effect of different concentrations of essential oils was determined by solid medium diffusion assay. Mycelial growth and sporulation were determined for each essential oil at the concentrations established by solid medium diffusion assay. At the fifth, seventh and ninth days the mycelial diameter (Ø mm) and spore production were also determined. FUN-1 staining was performed to assess cell viability after broth macrodilution assay. Trans-anethole, zingiberene, menthol and thymol are the major component of essential oils of fennel, ginger, mint and thyme, respectively. The effective concentrations for fennel, ginger, mint and thyme were 50, 80, 50 and 50% (oil/DMSO; v/v), respectively. The four essential oils analysed in this study showed antifungal effect. Additionally, FUN-1 staining showed to be a suitable method to evaluate cell viability of potential mycotoxigenic fungi A. flavus and A. parasiticus after treatment with essential oils.The authors are grateful to the colleagues from Laboratory of EPAMIG and Microbiology DEB/UFLA and the Micoteca da Universidade do Minho, Center for Biological Engineering, UMINHO for their support to perform this work. A special aknowledgment is also due to the FAPEMIG and MUM-UMINHO for the financial support of bench work and to CAPES for granting the first author with a PhD scholarship
Probabilistic model for the representation of the reservoir water level of concrete dams during normal operation periods
The dam’s reservoir water level varies over the year according to the water inflow and outflow, as a function of environmental events but also of dam exploitation management policy and human decisions. In the Portuguese dam safety regulation (RSB 2007), the normal water level (NWL) is considered as the optimum exploitation level. However, as proved by the continuous monitoring over the lifetime of a set of dams, the NWL is occasionally exceeded for non-negligible time periods. The reservoir water level, to which the water pressure on the upstream face is related, is a fundamental parameter for the safety and reliability analysis of concrete dams. When water-induced actions are considering the leading loads, only the maximum reservoir water level, usually associated with a high-return-period flood, is relevant. However, for other combinations, in particular, earthquake scenarios, the consideration of the variability of the water level over time is crucial. In reliability analysis of concrete dams, the reservoir water level has been considered either as a deterministic variable, once the loading scenario analyzed assume water-induced actions as leading loads (Westberg 2010), or as a random variable defined using hydrological site information of a specific study case (Altarejos et al. Structural Safety 36-37:1–13 2012). This work proposes a probabilistic model of the reservoir water level of any new dam based only on its geometrical properties, which provides a low-cost alternative to in-depth hydrological analysis. The proposed model can be useful in two stages of the lifecycle of dams: (i) initial design and feasibility stages, and (ii) routine safety assessment of existing structures, as in both stages the costs of a complete hydrological analysis is too high for the level of detail required. For that, the recorded reservoir water level of 27 Portuguese large concrete dams is used. A normalized sinusoidal model, with annual period, is adjusted to the reservoir water level annual history of those dams by beta regression. Generally, a good agreement between observations and the proposed model, for most of the annual adjustments, was achieved. The distribution parameters of the random variables were estimated through the maximum likelihood estimation (MLE) method. The physical, model and statistical uncertainties were quantified and can now be included in a reliability analysis procedur
Biochemical and Molecular Profiling of Wild Edible Mushrooms from Huila, Angola
The harvesting, processing, and sale of wild edible mushrooms (WEM) is a relevant economic activity in Angola and a good example of the use of non-wood forest products for food. Although there is deep traditional knowledge about the general properties of WEMs, a huge gap remains in detailed scientific knowledge. Thus, this study aimed to investigate the socio-economic importance of the species sold at local markets in Huila, Angola, from their molecular identification to the assessment of their nutritional, chemical, and bioactive profiles. From the eight WEM morphotypes studied, five were identified based on phenotypical and molecular approaches (four Russula spp., and Amanita loosei). The studied mushrooms proved to be a rich source of carbohydrates, proteins, and ashes, also presenting low amounts of fat. Chemical analyses further revealed mannitol as the main free sugar in all samples, and organic acids, namely, oxalic, quinic, malic, citric, and fumaric acids in low amounts. Additionally, the α-tocopherol isoform and monounsaturated fatty acids were predominant. Regarding phenolic acids, protocatechuic, p-hydroxybenzoic, p-coumaric, and cinnamic acids were detected in all mushroom hydroethanolic extracts, being responsible for their antioxidant, antibacterial, and antifungal activities. Our investigation contributes to the identification and knowledge of WEMs as important complementary food sources in Angola, some of which were reported for the first time, promoting their utilization as a basis of nutritional and functional ingredients, as being able to be part of a balanced diet and to be used in new bio-based formulations.info:eu-repo/semantics/publishedVersio
Biochemical and Molecular Profiling of Wild Edible Mushrooms from Huila, Angola
The harvesting, processing, and sale of wild edible mushrooms (WEM) is a relevant economic
activity in Angola and a good example of the use of non-wood forest products for food.
Although there is deep traditional knowledge about the general properties of WEMs, a huge gap
remains in detailed scientific knowledge. Thus, this study aimed to investigate the socio-economic
importance of the species sold at local markets in Huila, Angola, from their molecular identification
to the assessment of their nutritional, chemical, and bioactive profiles. From the eight WEM
morphotypes studied, five were identified based on phenotypical and molecular approaches (four
Russula spp., and Amanita loosei). The studied mushrooms proved to be a rich source of carbohydrates,
proteins, and ashes, also presenting low amounts of fat. Chemical analyses further revealed mannitol
as the main free sugar in all samples, and organic acids, namely, oxalic, quinic, malic, citric, and
fumaric acids in low amounts. Additionally, the -tocopherol isoform and monounsaturated fatty
acids were predominant. Regarding phenolic acids, protocatechuic, p-hydroxybenzoic, p-coumaric,
and cinnamic acids were detected in all mushroom hydroethanolic extracts, being responsible for
their antioxidant, antibacterial, and antifungal activities. Our investigation contributes to the identification
and knowledge of WEMs as important complementary food sources in Angola, some of which
were reported for the first time, promoting their utilization as a basis of nutritional and functional
ingredients, as being able to be part of a balanced diet and to be used in new bio-based formulationsinfo:eu-repo/semantics/publishedVersio
Mathematics learning and assessment using MathE platform: a case study
Universities are encouraging the implementation of innovative methodologies and
teaching strategies to develop an interactive and appealing educational environment
where students are the focus of the learning process. In such a personalised learning
environment, an increase of the students’ engagement and the improvement of the
outcomes arise. MathE has been developed to help achieve this goal. Based on collaborative
procedures, internet resources – both pre-existing and freely available as
well as resources specifically conceived by the project team – and communities of
practices, MathE intends to be a tool to nurture and stimulate the learning of Mathematics
in higher education. This study introduces and describes the MathE platform,
which is divided into three sections: Student’s Assessment, Library and Community
of Practice. An in-depth description of the Student’s Assessment section is presented
and an analysis of the results obtained from students, when using this feature of the
platform, is also provided. After this, and based on the answers to an online survey,
the impact of the MathE platform among students and teachers of eight countries is
shown. Although the number of collected results is still scarce, it allows the recognition
of a trend regarding the use of the material of the Student’s Assessment section
for autonomous study. The results indicate the platform is well organized, with a
satisfactory amount and diversity of questions and good interconnection between
the various parts. Nevertheless, both teachers and students indicate that more questions
should be introduced. The overall opinion about the MathE platform is very
favourableThe authors are grateful to FCT for financial support through national funds UIDB/05757/2020.The authors are grateful to FCT for financial support through national funds UIDB/05757/2020info:eu-repo/semantics/publishedVersio
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