1,666 research outputs found
Mapping of Alternative Oilseeds from the Brazilian Caatinga and Assessment of Catalytic Pathways toward Biofuels Production
Biofuels are increasingly important renewable resources in the world's energy matrix that have challenged the scientific community as well as small and large farmers to develop alternatives to fossil fuels in order to achieve the aims of energy transition. In particular, Brazil's proven competitiveness in agribusiness together with its rich biodiversity put the country in a key position in the biofuels market. The semiarid Caatinga of northeastern Brazil, an exclusive biome rich in many oilseed species suitable for potential energy purposes, is of particular interest in this field. Nowadays, soybeans are the main feedstock used for the production of biodiesel, but, due to the increasing demand for biofuels, the search for alternative sources of oil from tropical flora with high productivity is crucial. Under this premise, this systematic review focuses on mapping Caatinga's vegetable oil crops that could be used as alternative raw materials for biofuels' production in Brazil, in addition to traditional soybeans and sugarcane. To gain more detailed insight into these matrices, their main properties, including oil content, fatty acid profile and physicochemical properties, are discussed. Moreover, an overview is provided of processes to synthesize different types of biofuels, particularly biodiesel and aviation biokerosene, including the routes employing homogeneous, enzymatic and mainly heterogeneous catalysts. Finally, future prospects and challenges for renewable biofuels and the Caatinga biome are addressed
Somites without a clock
The formation of body segments (somites) in vertebrate embryos is accompanied by molecular oscillations ("segmentation clock"). Interaction of this with a wave travelling along the body axis (the "clock-and-wavefront model") is generally believed to control somite number, size and axial identity. Here, we show that a clock-and-wavefront is unnecessary for somite formation. Non-somite mesoderm treated with Noggin generates many somites that form simultaneously, without cyclic expression of Notch-pathway genes, yet have normal size, shape and fate. These somites have axial identity: the Hox-code is fixed independently of somite fate. However they are not subdivided into rostral and caudal halves, necessary for neural segmentation. We propose that somites are self-organizing structures whose size and shape is controlled by local cell-cell interactions
Piezoelectric coefficients d(14), d(16), d(34) and d(36) of an L-arginine hydrochloride monohydrate crystal by X-ray three-beam diffraction
Previous work employed X-ray three-beam diffraction techniques to obtain part of the L-arginine hydrochloride monohydrate (L-AHCL. H2O) piezoelectric coefficients, namely d(21), d(22), d(23) and d(25). Those coefficients were obtained by measuring the shift in the angular position of a number of secondary reflections as a function of the electric field applied in the [ 010] piezoelectric direction. In this paper a similar procedure has been used to measure the remaining four piezoelectric coefficients in L-AHCL. H2O: with the electric field applied in the [100] direction, d(14) and d(16) were measured; with the electric field applied in the [001] direction, d(34) and d(36) were obtained. Therefore the entire piezoelectric matrix of the L-AHCL. H2O crystal has been successfully measured.13643543
Proposal to produce long-lived mesoscopic superpositions through an atom-driven field interaction
We present a proposal for the production of longer-lived mesoscopic
superpositions which relies on two requirements: parametric amplification and
squeezed vacuum reservoir for cavity-field states. Our proposal involves the
interaction of a two-level atom with a cavity field which is simultaneously
subjected to amplification processes.Comment: 12 pages, title changed, text improved and refences adde
Elimination of biliary stones through the urinary tract: a complication of the laparoscopic cholecystectomy
Conhecimento e uso de cigarros eletrônicos e percepção de risco no Brasil: resultados de um país com requisitos regulatórios rígidos
Changes in cigarette consumption patterns among Brazilian smokers between 1989 and 2008
Sialic Acid Glycobiology Unveils Trypanosoma cruzi Trypomastigote Membrane Physiology.
Trypanosoma cruzi, the flagellate protozoan agent of Chagas disease or American trypanosomiasis, is unable to synthesize sialic acids de novo. Mucins and trans-sialidase (TS) are substrate and enzyme, respectively, of the glycobiological system that scavenges sialic acid from the host in a crucial interplay for T. cruzi life cycle. The acquisition of the sialyl residue allows the parasite to avoid lysis by serum factors and to interact with the host cell. A major drawback to studying the sialylation kinetics and turnover of the trypomastigote glycoconjugates is the difficulty to identify and follow the recently acquired sialyl residues. To tackle this issue, we followed an unnatural sugar approach as bioorthogonal chemical reporters, where the use of azidosialyl residues allowed identifying the acquired sugar. Advanced microscopy techniques, together with biochemical methods, were used to study the trypomastigote membrane from its glycobiological perspective. Main sialyl acceptors were identified as mucins by biochemical procedures and protein markers. Together with determining their shedding and turnover rates, we also report that several membrane proteins, including TS and its substrates, both glycosylphosphatidylinositol-anchored proteins, are separately distributed on parasite surface and contained in different and highly stable membrane microdomains. Notably, labeling for α(1,3)Galactosyl residues only partially colocalize with sialylated mucins, indicating that two species of glycosylated mucins do exist, which are segregated at the parasite surface. Moreover, sialylated mucins were included in lipid-raft-domains, whereas TS molecules are not. The location of the surface-anchored TS resulted too far off as to be capable to sialylate mucins, a role played by the shed TS instead. Phosphatidylinositol-phospholipase-C activity is actually not present in trypomastigotes. Therefore, shedding of TS occurs via microvesicles instead of as a fully soluble form
Silvopastoral systems as a tool for territorial sustainability and biodiversity
Rural and livestock population evolution in the inner north of Portugal
has demonstrated a great regression with consequences for environment and nature
conservation. In this context, and taking into account that pastoral activity has
shaped the natural areas of mountain territories since its beginning and that territories
are currently part of Natura 2000 network, rethinking the importance of such
activity has become vital. The constraints affecting daily tasks performed by shepherds
and livestock breeders as well as the installed social segregation are a strong
limitation. However, current research developed in the context of nature conservation
has demonstrated the importance of the landscape mosaic promoted by grazing
in the preservation of priority habitats. In this way, it is urgent to assess the issue of
shepherds and livestock breeders’ image in terms of their roles, relationships and
concerns, as well as to assess pastoralism socioeconomics in regard to self-consumption,
market and rural self-sufficiency. In this perspective, this work
presents an analysis of the adaptation of grazing to current times, perceiving its
limitations and success potential.This work is supported by European Structural and Investment Funds,
FEDER component, through the Operational Competitiveness and Internationalization Programme
(COMPETE 2020) [Project No. 006971 (UID/SOC/04011)], and national funds, through FCT,
Portuguese Foundation for Science and Technology under project UID/SOC/04011/2013.info:eu-repo/semantics/publishedVersio
Development and content validity of the perceived barriers with antiretroviral treatment scale.
Introdu??o: Pessoas vivendo com HIV (PVHA) devem ser devidamente orientadas
para iniciar a terapia antirretroviral (TARV), sendo importante identificar as dificuldades
de PVHA com o tratamento, no intuito de realizar interven??es para prevenir uma
poss?vel falha terap?utica. Objetivos: Desenvolver uma escala para avaliar a percep??o
de dificuldades de PVHA com a TARV e analisar sua validade de conte?do. M?todos:
Uma escala contendo 47 itens foi proposta a partir de um estudo qualitativo pr?vio e,
entre junho e agosto de 2015, foi aplicada em 27 PVHA em tratamento no Hospital Eduardo
de Menezes para avaliar a compreens?o dos itens pela popula??o alvo (an?lise
sem?ntica). Os itens foram modificados e avaliados por tr?s ju?zes quanto ? relev?ncia,
adequa??o e dimensionalidade, utilizando-se o coeficiente de validade do conte?do e
coeficiente kappa. Resultados: Ap?s an?lise sem?ntica os itens foram reduzidos para
40. Nenhum item foi exclu?do ap?s an?lise de ju?zes, uma vez que todos foram considerados
relevantes. Apenas 30% dos itens foram modificados ap?s serem considerados
inadequados. A maior dificuldade dos ju?zes foi classificar itens sobre a adequa??o do
medicamento ? rotina entre as dimens?es. Conclus?es: Os resultados apontaram a
adequa??o da escala ao conte?do que ela pretende avaliar. A vers?o piloto da escala
est? sendo testada empiricamente e poder? ser usada no servi?o de sa?de, em n?vel
individual, identificando os casos nos quais ? necess?rio prover educa??o e aconselhamento
ao paciente, bem como instrumento de pesquisa, em n?vel coletivo, para o
planejamento de interven??es e de pol?ticas p?blicas.Introduction: People living with HIV (PLHIV) should be properly informed when starting
antiretroviral therapy (ART). It is important to identify the difficulties of PLHIV, in order to
implement interventions to prevent a possible treatment failure. Objectives: To develop a
scale to measure the perceived difficulty of PLHIV with ART and analyze its content validity.
Methods: A scale containing 47 items was proposed from previous qualitative study.
Between June and August 2015, it was applied to 27 PLHIV under treatment at Eduardo de
Menezes Hospital to assess the comprehension of items by the target population (semantic
analysis). The items were modified and evaluated by three judges regarding the relevance,
appropriateness and dimensionality, using the validity of the content and kappa coefficients.
Results: After semantic analysis the items were reduced to 40. No items were excluded after
analysis of judges, since all were considered relevant. Only 30% of the items were modified
after being considered unsuitable. The main difficulty of judges was to evaluate items
on their appropriateness of the medication use between dimensions. Conclusions: Results indicated the suitability of the scale to the content that it
intends to evaluate. The scale of the pilot version is being
tested empirically and can be used in the health service at
the individual level, identifying cases where it is necessary
to provide education and counseling to the patient,
as well as a research tool, at the collective level, to plan
interventions and public policies
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