Reduced mechanism for combustion of hydrogen and methane with nitrogen chemistry

A reduced chemical kinetic reaction mechanism that could be used in computational fluid dynamics (CFD) software was developed to describe the formation of nitrogen oxides and their subsequent destruction in hydrogen and/or hydrocarbon flames with or without seeding of nitrogen compounds. The research work presented here will describe the numerical work done with the application "CHEMKIN" in order to verify the quality of the reduced mechanism. The mechanism was validated through comparisons between computational data from a variety of different sources. In addition, numerical experiments were carried out to examine features of methane combustion in which the detailed mechanisms can be used to compare their response. The proposed reduced mechanism provides reasonable agreement with the studied detailed mechanisms, mainly in the species produced from the hydrocarbon oxidation process. Regarding the produced nitrogen species, the proposed reduced mechanism showed the same tendencies as the detailed mechanisms, but there is a need for a better agreement regarding the quantities

Meningite Tuberculosa. Revisão de 7 Anos

A meningite tuberculosa é uma complicação grave da infecção pelo Mycobacterium tuberculosis. Entre 1 de Janeiro 1989 e 31 de Dezembro de 1995 foram internadas 14 crianças na Unidade de Doenças Infecciosas do Serviço 2 do Hospital D. Estefânia (HDE), por meningite tuberculosa, enquanto nos 6 anos anteriores, tinham sido admitidas 22 crianças, com a mesma patologia. A maioria das crianças tinha idade superior a 5 anos (64%). A fonte de contágio foi identificada em 35,7% dos casos e 79% tinham sido vacinadas com BCG. Em 78,5% foi detectado compromisso neurológico focal. Todas fizeram tratamento com 4 antibacilares. Houve necessidade de intervenção neurocirúrgica em 21% dos doentes. Em 57% dos casos persistiram sequelas neurológicas no final do tratamento. Não se registaram casos de morte

Synthesis of sub-5 nm Co-doped SnO2_2 nanoparticles and their structural, microstructural, optical and photocatalytic properties

A swift chemical route to synthesize Co-doped SnO$_2$ nanopowders is described. Pure and highly stable Sn$_{1-x}$Co$_x$O$_{2-\delta}$ (0 $\le$ x $\le$ 0.15) crystalline nanoparticles were synthesized, with mean grain sizes < 5 nm and the dopant element homogeneously distributed in substitutional sites of the SnO$_2$ matrix. The UV-visible diffuse reflectance spectra of the Sn$_{1-x}$Co$_x$O$_{2-\delta}$ samples reveal red shifts, the optical bandgap energies decreasing with increasing Co concentration. The Urbach energies of the samples were calculated and correlated with their bandgap energies. The photocatalytic activity of the Sn$_{1-x}$Co$_x$O$_{2-\delta}$ samples was investigated for the 4-hydroxylbenzoic acid (4-HBA) degradation process. A complete photodegradation of a 10 ppm 4-HBA solution was achieved using 0.02% (w/w) of Sn$_{0.95}$Co$_{0.05}$O$_{2-\delta}$ nanoparticles in 60 min of irradiation.Comment: 29 pages, 2 tables, 10 figure

Phenolic Acids, Phenolic Aldehydes and Furanic Derivatives in Oak Chips: American vs. French Oaks

Phenolic acids (gallic, vanillic, syringic and ellagic acids), phenolic aldehydes (vanillin, syringaldehyde,coniferaldehyde and sinapaldehyde) and furanic derivatives (furfural, 5-methylfurfural and5-hydroxymethylfurfural) were quantified in commercial American and French oak chips. Chips withdifferent sizes and toast degrees were used. Compounds were extracted directly from the wood samples inorder to determine possible differences among woods as well as toast degree. Likewise, the compounds wereextracted from a synthetic wine solution to which the chip woods had been added. The results show thatFrench wood chips are generally richer than the American ones. The total amount of phenolic compoundsincreases with toasting level, with the non-toasted chips being the poorest ones. The degree of extractionfrom the synthetic wine solution seems to be related to the shape of the chips, rather than to the wood typeor toast degree

Thermodynamics of co-translational folding and ribosome–nascent chain interactions

Proteins can begin the conformational search for their native structure in parallel with biosynthesis on the ribosome, in a process termed co-translational folding. In contrast to the reversible folding of isolated domains, as a nascent chain emerges from the ribosome exit tunnel during translation the free energy landscape it explores also evolves as a function of chain length. While this presents a substantially more complex measurement problem, this review will outline the progress that has been made recently in understanding, quantitatively, the process by which a nascent chain attains its full native stability, as well as the mechanisms through which interactions with the nearby ribosome surface can perturb or modulate this process

Thermal restraint and fire resistance of columns

A proposal is made, based on the results of a series of tests and calculations, with the aim of being used as a simple method to correct the value of the critical temperature of steel columns free to elongate, in order to take into account the restraint effect of the structure to which they belong in a practical situation. To better illustrate the possible types of behaviour of heated steel columns with elastic restraint to the thermal elongation, and the reasons why the critical temperature of axially loaded slender steel columns with thermal restraint can sometimes be lower than the critical temperature of the same columns free to elongate, a simple model is presented and used in a qualitative analysis.http://www.sciencedirect.com/science/article/B6V37-46WW50B-1/1/139a30367738460772843d1279c4c32

Semen Cryopreservation in Brazilian Freshwater Fish: Advances and Main Challenges

Studies on semen cryopreservation in Brazilian freshwater fish have been growing in number of publications and investigated species. Despite this apparent increase in research, standardization of cryoprotocols is still missing, making it clear that the grounds on the quality of cryopreserved semen has not yet reached a level that guarantee satisfactory results for its replication. This chapter aims to make a critical and reflective analysis on the ways cryopreservation of freshwater fish semen has been conducted in Brazil. The difficulties in standardizing protocols, broodstock, and selection of genetically superior animals; the barriers in transferring technology from laboratory benches to the field and make feasible the use of cryopreserved semen on a commercial scale; the formation of germplasm banks and the responsible use of cryopreserved material are also discussed. We have no intention to point out the successes and mistakes that may have been committed in pursuing development of cryopreservation protocols, but a reflection on the future directions considering what should be pondered on this subject with objectivity and scientific consolidation

Nascent chain dynamics and ribosome interactions within folded ribosome-nascent chain complexes observed by NMR spectroscopy

The folding of many proteins can begin during biosynthesis on the ribosome and can be modulated by the ribosome itself. Such perturbations are generally believed to be mediated through interactions between the nascent chain and the ribosome surface, but despite recent progress in characterising interactions of unfolded states with the ribosome, and their impact on the initiation of co-translational folding, a complete quantitative analysis of interactions across both folded and unfolded states of a nascent chain has yet to be realised. Here we apply solution-state NMR spectroscopy to measure transverse proton relaxation rates for methyl groups in folded ribosome–nascent chain complexes of the FLN5 filamin domain. We observe substantial increases in relaxation rates for the nascent chain relative to the isolated domain, which can be related to changes in effective rotational correlation times using measurements of relaxation and cross-correlated relaxation in the isolated domain. Using this approach, we can identify interactions between the nascent chain and the ribosome surface, driven predominantly by electrostatics, and by measuring the change in these interactions as the subsequent FLN6 domain emerges, we may deduce their impact on the free energy landscapes associated with the co-translational folding process

The hydrogen roadmap in the Portuguese energy system : developing the P2G case

ABSTRACT: The planning and implementation of the Portuguese energy transition towards a decarbonized, energy secure and more sustainable economy is providing driving forces for significant challenges and opportunities on a country basis. The emergence of hydrogen (H2) within low-carbon pathways in the energy system requires to deal with the complexity of H2 carrier in its relationship with energy sources and end use sectors. In the frame of mainland Portugal energy system, different value chain configurations were analysed and assessed using energy analysis, lifecycle thinking and impacts assessment, as well as the technology and costs analysis, within an approach to the Hydrogen Economy. The Portuguese Roadmap for H2 was developed taking such an approach and therein the evolution of the selected value chains along time. Among these, ‘power-to-gas’ (P2G) combined with the gas grid is given an in-depth focus, as it was prioritized as the top value chain to answer the research question: how sustainable would be the hydrogen production and end use in Portugal within the P2G value chain? This P2G value chain with a particular focus on heating applications is discussed on the basis of the technology options and technology maturity identified in each main stage of the value chain, using analytical dimensions such as the energy efficiency and greenhouse gas emissions, among other impact categories, followed by a sensitivity analysis. The obtained results enable to show how case-sensitive that approach is and that a multi-decisional process is required to assist the planning stage.info:eu-repo/semantics/publishedVersio