781 research outputs found
Low temperature matrix-isolation and solid state vibrational spectra of tetrazole
Infrared spectra of tetrazole (CN isolated in an argon matrix (T \10 K) and in the solid state (at room 4H2) temperature) were investigated. In the crystalline phase, tetrazole exists in its 1H-tautomeric form and new assignments of the vibrational spectra (both infrared and Raman) of this phase are presented. The infrared spectrum of the matrix-isolated monomeric form of tetrazole is now reported and assigned for the Ðrst time, showing essentially the expected signature of the 2H-tetrazole tautomer. From relative intensities of the
infrared bands ascribable to the two tautomers, the amount of the 1H-tautomer in the argon matrix was estimated to be ca. 10% of the most stable tautomer. Assuming that gas-phase relative populations of the two
tautomers could be efficiently trapped in the argon matrix during deposition, the energy di erence between 1H- and 2H-tetrazole (*E was then obtained. The experimental value, kJ mol~1, 1Hh2H) *E1Hh2H\6.95^1.50 now determined for the Ðrst time, compares fairly well with the theoretical predictions for the molecule in
vacuum (e.g., the zero point vibrational energy corrected energy di erence obtained at the B3LYP/6È31G* level of theory is 9.96 kJ mol~1)
UCP2 and ANT differently modulate proton-leak in brain mitochondria of long-term hyperglycemic and recurrent hypoglycemic rats
A growing body of evidence suggests that mitochondrial
proton-leak functions as a regulator of reactive
oxygen species production and its modulation may limit
oxidative injury to tissues. The main purpose of this work
was to characterize the proton-leak of brain cortical mitochondria
from long-term hyperglycemic and insulininduced
recurrent hypoglycemic rats through the modulation
of the uncoupling protein 2 (UCP2) and adenine nucleotide
translocator (ANT). Streptozotocin-induced diabetic
rats were treated subcutaneously with twice-daily insulin
injections during 2 weeks to induce the hypoglycemic episodes.
No differences in the basal proton-leak, UCP2 and
ANT protein levels were observed between the experimental
groups. Mitochondria from recurrent hypoglycemic rats
presented a decrease in proton-leak in the presence of
GDP, a specific UCP2 inhibitor, while an increase in
proton-leak was observed in the presence of linoleic acid,
a proton-leak activator, this effect being reverted by the
simultaneous addition of GDP. Mitochondria from longterm
hyperglycemic rats showed an enhanced susceptibility
to ANT modulation as demonstrated by the complete inhibition
of basal and linoleic acid-induced proton-leak caused
by the ANT specific inhibitor carboxyatractyloside. Our
results show that recurrent-hypoglycemia renders mitochondria
more susceptible to UCPs modulation while the protonleak
of long-term hyperglycemic rats is mainly modulated
by ANT, which suggest that brain cortical mitochondria
have distinct adaptation mechanisms in face of different
metabolic insults.The authors’ work is supported by the Fundação
para a Ciência e a Tecnologia (FCT) (PTDC/SAU-NEU/103325/2008)
co-funded by Fundo Europeu de Desenvolvimento Regional (FEDER)
via Programa Operacional Factores de Competitividade (COMPETE).
Susana Cardoso has a PhD fellowship from the Portuguese Foundation
for Science and Technology (SFRH/BD/43968/2008)
Characterization of several hazelnut (Corylus avellana L.) cultivars based in chemical, fatty acid and sterol composition
Nineteen cultivars of hazelnuts (Corylus avellana L.) collected during the 2001 crop, from Vila Real, Portugal, were analysed for chemical composition, including
moisture, total oil content, crude protein, ash, carbohydrates
and nutritional value. Fat was the predominant
component, ranging from 59.3 to 69.0%. Total oil was extracted
and analysed for fatty acid and sterol compositions
and oxidative stability. Fatty acid and sterol compositions
were determined by Gas–Liquid Chromatography coupled
to a Flame Ionisation Detector (GLC/FID). Monounsaturated
fatty acids, particularly oleic acid, were predominant
(78.7–84.6%). Total phytosterol content ranged from 133.8
to 263.0 mg/100 g of oil. Among the nine sterols identified and quantified, β-sitosterol was the major one with
a mean percentage of 83.6%, while Δ5-avenasterol and
campesterol were the second and the third components of
the group with mean values of 6.1 and 5.8%, respectively.
Since hazelnut oil can be used in olive oil adulteration,
the values obtained were compared with published mean
values of olive oils from different geographical origins
Low temperature matrix-isolation and solid state vibrational spectra of 5-chlorotetrazole
The vibrational spectra of 5-chlorotetrazole (CN4HCl) isolated in an argon matrix (T ¼ 8.5 K) and in the solid state (at room temperature) were studied. The infrared spectrum of monomers of 5-chlorotetrazole isolated in an argon matrix agrees well with the spectrum predicted theoretically (DFT(B3LYP)/6-31G*) for the 2Htautomer of the compound. The bands assigned to the 1H-tautomer appear in the experimental spectrum as very low intensity features. Based on the relative intensities of the bands in the spectra of the 1H- and 2Htautomers, the relative amount of the first tautomer in this matrix can be estimated as 1%. Three matrixes were deposited with different nozzle temperatures and the enthalpy difference between the tautomers DH ¼ 8.0 kJ
mol 1 was estimated using the Van’t Hoff relation. The internal energy difference between the two tautomers was predicted theoretically (DFT B3LYP/6-31G*) as 12.6 kJ mol 1. This is in reasonable agreement with
experimental observations. In the crystalline phase, this compound exists in its 1H-tautomeric form. Accordingly, the IR spectrum of polycrystalline 5-chlorotetrazole is well reproduced by the spectrum predicted theoretically for the 1H- tautomer
Difficulties inadaptationand academic performance in higher education: ananalysis in terms of vocational preferences and level of education
[Resumo] Assiste-se a urna maior sensibilidade por parte dos investigadores e autoridades académicas com as dificuldades de adaptaçao e de realizaçao dos estudantes do Ensino Superior. Tais dificuldades sao particularmente sentidas junto dos alunos do 10 ano. Um projecto de investigaçao neste dominio decorre na Universidade do Minho. Neste artigo apresentam- se alguns dados descritivos das dificuldades académicas de urna amostra portuguesa de estudantes do Ensino Superior (n=370), tomando-se quer o facto dos estudantes poderem ou nao estarem a frequentar o curso e estabelecimento de ensino correspondente a sua 1ª escolha vocacional, quer o ano escolar em que os estudantes se encontram. Os resultados sugerem que as dificuldades académicas nas áreas avaliadas nao se diferenciam de acordo com as opçoes vocacionais dos estudantes, muito embora algumas diferenzas sao encontradas quando comparamos os alunos dos anos iniciais e terminais do curso superior que frequentam
Mitochondrial Preconditioning: A Potential Neuroprotective Strategy
Mitochondria have long been known as the powerhouse of the cell. However, these organelles are also pivotal players in neuronal cell death. Mitochondrial dysfunction is a prominent feature of chronic brain disorders, including Alzheimer's disease (AD) and Parkinson's disease (PD), and cerebral ischemic stroke. Data derived from morphologic, biochemical, and molecular genetic studies indicate that mitochondria constitute a convergence point for neurodegeneration. Conversely, mitochondria have also been implicated in the neuroprotective signaling processes of preconditioning. Despite the precise molecular mechanisms underlying preconditioning-induced brain tolerance are still unclear, mitochondrial reactive oxygen species generation and mitochondrial ATP-sensitive potassium channels activation have been shown to be involved in the preconditioning phenomenon. This review intends to discuss how mitochondrial malfunction contributes to the onset and progression of cerebral ischemic stroke and AD and PD, two major neurodegenerative disorders. The role of mitochondrial mechanisms involved in the preconditioning-mediated neuroprotective events will be also discussed. Mitochondrial targeted preconditioning may represent a promising therapeutic weapon to fight neurodegeneration
Low water supply differentially affects the growth, yield and mineral profile of kabuli and desi chickpeas (cicer arietinum)
The climatic events predicted to increase in intensity and frequency in the near future, including drought, may influence the quality and productivity of several important crops for human nutrition, such as legumes. Herein, two chickpea genotypes (Cicer arietinum) were analysed for their resilience to low water supply: a commercial white chickpea (kabuli), and a black chickpea (desi) with marginal production in occidental countries. Plants were grown under four levels of water supplies (90, 75, 50 and 25% of field capacity), and biometric variables (root, shoot, pods and seeds), proxies of plant fitness (water content and oxidative stress) and the seed nutritional profile (protein and mineral concentrations) were analysed at plant maturity. Results show that water content in shoots and roots decreased with decreasing water supplies, with kabuli plants generally having higher water content in shoots and desi in roots. Shoot length was significantly higher in kabuli compared to desi, while root length increased up to 11% in both species with decreasing water supplies. The root-to-shoot ratio was higher in kabuli and increased with decreasing water supply, being negatively correlated with the number of pods and seeds per plant. Lipid peroxidation increased with decreasing water supply, having slight positive correlations with plant growth parameters while being negatively correlated with plant productivity. No significant effects of plant genotype and water supply were observed on seed K, Ca, and protein, but desi was able to sustain higher P, Mg, Zn, Fe, Mn and B than kabuli, including at lower water supplies. Results suggest that water stress negatively impacts plant growth and productivity and that the two chickpea genotypes have distinct biomass and water allocation strategies to cope with low water supply. These findings may be useful in strategies for improving the productivity and nutritional profile of chickpea crops under water-limited conditions.info:eu-repo/semantics/publishedVersio
Trehalose alleviates the phenotype of Machado–Joseph disease mouse models
Machado-Joseph disease (MJD), also known as spinocerebellar ataxia type 3, is the most common of the dominantly inherited ataxias worldwide and is characterized by mutant ataxin-3 aggregation and neuronal degeneration. There is no treatment available to block or delay disease progression. In this work we investigated whether trehalose, a natural occurring disaccharide widely used in food and cosmetic industry, would rescue biochemical, behavioral and neuropathological features of an in vitro and of a severe MJD transgenic mouse model.This work was funded by BioBlast Pharma, the ERDF through the Regional
Operational Program Center 2020, Competitiveness Factors Operational
Program (COMPETE 2020) and National Funds through FCT (Foundation
for Science and Technology) - SFRH/BD/87404/2012, BrainHealth2020
projects (CENTRO-01-0145-FEDER-000008), ViraVector (CENTRO-01-0145FEDER-022095), CortaCAGs (POCI-01-0145-FEDER-016719), SpreadSilenc‑ing POCI-01-0145-FEDER-029716 and POCI-01-0145-FEDER-007440, as well
as the SynSpread, ESMI and ModelPolyQ under the EU Joint ProgramNeurodegenerative Disease Research (JPND), the last two co-funded bythe European Union H2020 program, GA No. 643417; by National Ataxia
Foundation (USA), the American Portuguese Biomedical Research Fund
(APBRF) and the Richard Chin and Lily Lock Machado–Joseph Disease
Research Fund.info:eu-repo/semantics/publishedVersio
Maize open-pollinated populations physiological improvement: validating tools for drought response participatory selection
Participatory selection—exploiting specific adaptation traits to target environments—helps
to guarantees yield stability in a changing climate, in particular under low-input or organic production.
The purpose of the present study was to identify reliable, low-cost, fast and easy-to-use tools to
complement traditional selection for an e ective participatory improvement of maize populations
for drought resistance/tolerance. The morphological and eco-physiological responses to progressive
water deprivation of four maize open-pollinated populations were assessed in both controlled and
field conditions. Thermography and Chl a fluorescence, validated by gas exchange indicated that the
best performing populations under water-deficit conditions were ‘Fandango’ and to a less extent
‘Pigarro’ (both from participatory breeding). These populations showed high yield potential under
optimal and reduced watering. Under moderate water stress, ‘Bilhó’, originating from an altitude of
800 m, is one of the most resilient populations. The experiments under chamber conditions confirmed
the existence of genetic variability within ‘Pigarro’ and ‘Fandango’ for drought response relevant for
future populations breeding. Based on the easiness to score and population discriminatory power,
the performance index (PIABS) emerges as an integrative phenotyping tool to use as a refinement of
the common participatory maize selection especially under moderate water deprivationinfo:eu-repo/semantics/publishedVersio
Measuring the activity of European and African Countries using Social Accounting Matrices
Economic models at the micro, meso and macro levels presuppose the existence of consistent
databases that make it possible to quantify the activity of enterprises, sectors, regions, countries or
continents. Such models can also be important aids in the policy decision process, since they permit
the construction of scenarios resulting from the adoption of policy measures and the consequent
changes that they introduce.
When consistent with the United Nations System of National Accounts (SNA), the Social
Accounting Matrix (SAM) can include all the nominal flows of the measured part of the economy,
at the level of both production and the institutions, and therefore satisfies these requirements. Thus,
in its numerical version, a SAM constitutes a database and provides a snapshot of the measured
reality at a certain moment, whereas its possible algebraic versions, i.e. models that are based upon
it, permit the construction of the above-mentioned scenarios.
The possibility and usefulness of constructing SAMs for African countries consistent with the SNA
will be examined and experimented. The SAM’s basic structure and consistency within the whole
system will be studied, as well as any possible disaggregations, extensions, aggregates, indicators
and balances that can be calculated. Other aspects beyond that basic structure will also be examined
in order to show to what extent the SAM is capable of covering parts of the economy that are not
covered by the SNA.info:eu-repo/semantics/publishedVersio
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