Produção de biodiesel a partir de matéria-prima do sector oleíco

Dada a crescente procura de matérias-primas alternativas para a produção de biodiesel testou-se, neste trabalho, a viabilidade de utilização de produtos ligados ao sector oleícola, nomeadamente azeite lampante e óleo de bagaço de azeitona. Numa primeira fase, este material glicerídico foi caracterizado em termos de parâmetros que têm influência no processo de transformação em biodiesel e na qualidade deste produto. Observou-se, por exemplo, que ambas as matérias-primas possuem um indíce de iodo bastante mais favorável (78-85) do que óleos vegetais como a soja ou o girassol, que apresentam valores para este parâmetro superiores aos permitidos pela norma europeia de qualidade do biodiesel. Por outro lado, os valores determinados para o indíce de acidez quer no azeite lampante (7 mg KOH/g) quer no óleo de bagaço de azeitona (22 mg KOH/g) foram bastante elevados e mostraram que a produção de biodiesel não devia ser realizada pelo processo tecnológico mais tradicional. Por este facto, um primeiro passo de catálise ácida foi optimizado, através da metodologia do desenho factorial, em termos de concentração de catalisador, tempo de reacção e razão molar metanol/ácidos gordos livres, de modo a determinar quais as condições que conduziam a uma diminuição do teor em ácidos gordos livres, para valores que permitissem prosseguir com a reacção de transesterificação por catálise básica (< 2 mg KOH/g). Esta última foi depois realizada em condições previamente definidas para outros óleos (razão molar metanol:óleo de 6:1, 1 % catalisador, 55ºC e 500 rpm), e o biocombustível obtido foi caracterizado de acordo com as especificações da norma EN 14214. Os resultados obtidos mostraram que estas matérias-primas podem constituir uma alternativa para o fabrico de biodiesel, o que corresponderá também a apresentar alternativas de utilização para o sector oleícola, fomentando o consumo de produtos de melhor qualidade para fins alimentares

Descrição e Análise Crítica do Regime de Fruta Escolar em Portugal

A alimentação saudável é um factor determinante para a promoção e protecção da saúde. Os hortofrutícolas, enquanto componentes de uma alimentação saudável, parecem exercer um efeito protector num vasto leque de doenças crónicas. Porém, vários estudos demonstram consumos, em crianças, inferiores às recomendações. O objectivo deste trabalho é descrever e analisar criticamente o percurso da estratégia portuguesa para a promoção do consumo de hortofrutícolas a nível escolar, o Regime de Fruta Escolar, e ao mesmo tempo fazer uma revisão da literatura no que diz respeito ao impacto de outros programas semelhantes implementados noutros países. Este programa é co-financiado através de ajuda comunitária para aquisição e distribuição de produtos hortofrutícolas a crianças, em idade escolar, que frequentem estabelecimentos de ensino público, englobando dois tipos de medidas: distribuição gratuita de hortofrutícolas e medidas de acompanhamento para promover o consumo. Diversos estudos sugerem que estes programas são eficazes no aumento do consumo de hortofrutícolas em crianças emidade escolar, contribuindo ainda para o desenvolvimento e melhoria dos conhecimentos acerca dos seus benefícios para a saúde. Pode também ser uma estratégia eficaz na redução das desigualdades sociais na saúde. Justifica-se o investimento neste tipo de programas como medida de saúde pública para o combate à obesidade e ao baixo consumo de hortofrutícolas.A healthy diet is a determinant factor for health promotion and protection. Fruit and vegetables, as a part of a healthy diet, seem to play an important protective role in a large number of chronic diseases. However, several studies show that, in children, the fruit and vegetable intake is below the recommended levels. The main objective of this work is to describe and critically analyze the Portuguese strategy for the promotion of fruit and vegetables consumption at school environment, the School Fruit Scheme. This program is co-financed by European Commission for fruit and vegetables acquisition and supplying for school-aged children, attending public schools, including two different types of measures: free fruit and vegetables supply and accompanying measures to promote consumption. Several studies suggest that these programs are effective at increasing fruit and vegetables intake in school-aged children, contributing also to the development and improvement of health benefits' knowledge. It can also be an efficient strategy to reduce the social inequalities in health. The investment in these kind of programs as a public health measure to fight obesity and low fruit and vegetables intake is thus justified

Arabidopsis plasma membrane intrinsic protein (AtPIP2;1) is implicated in a salinity conditional influence on seed germination

Published Online 6/6/2023 OnlinePublDynamic changes in aquaporin gene expression occur during seed germination. One example is the ~30-fold increase in Arabidopsis thaliana PIP2;1 transcripts within 24 h of seed imbibition. To investigate whether AtPIP2;1 can influence seed germination wild-type Columbia-0, single (Atpip2;1) and double (Atpip2;1-Atpip2;2) loss-of-function mutants, along with transgenic 2x35S::AtPIP2;1 over-expressing (OE) lines and null-segregant controls, were examined. The various genotypes were germinated in control and saline (75 mM NaCl treatment) conditions and tested for germination efficiency, imbibed seed maximum cross sectional (MCS) area, imbibed seed mass, and seed Na+ and K+ content. Seed lacking functional AtPIP2;1 and/or AtPIP2;2 proteins or constitutively over-expressing AtPIP2;1, had delayed germination in saline conditions relative to wild-type and null-segregant seed, respectively. Exposure to saline germination conditions resulted in Atpip2;1 mutants having greater imbibed seed mass and less accumulated Na+ than wild-type, whereas lines over-expressing AtPIP2;1 had reduced imbibed seed mass and greater seed K+ content than null-segregant control seed. The results imply a role for AtPIP2;1 in seed germination processes, whether directly through its capacity for water and ion transport or H2O2 signalling, or indirectly through potentially triggering dynamic differential regulation of other aquaporins expressed during germination. Future research will aid in dissecting the aquaporin functions influencing germination and may lead to novel solutions for optimising germination in sub-optimal conditions, such as saline soils.Phan Thi Thanh Hoai, Jiaen Qiu, Michael Groszmann, Annamaria De Rosa, Stephen D. Tyerman and Caitlin S. Byr

On the Progenitors of Core-Collapse Supernovae

Theory holds that a star born with an initial mass between about 8 and 140 times the mass of the Sun will end its life through the catastrophic gravitational collapse of its iron core to a neutron star or black hole. This core collapse process is thought to usually be accompanied by the ejection of the star's envelope as a supernova. This established theory is now being tested observationally, with over three dozen core-collapse supernovae having had the properties of their progenitor stars directly measured through the examination of high-resolution images taken prior to the explosion. Here I review what has been learned from these studies and briefly examine the potential impact on stellar evolution theory, the existence of "failed supernovae", and our understanding of the core-collapse explosion mechanism.Comment: 7 Pages, invited review accepted for publication by Astrophysics and Space Science (special HEDLA 2010 issue

Probing the Biosafety of Implantable Artificial Secretory Granules for the Sustained Release of Bioactive Proteins

Altres ajuts: acords transformatius de la UABAmong bio-inspired protein materials, secretory protein microparticles are of clinical interest as self-contained, slow protein delivery platforms that mimic secretory granules of the human endocrine system, in which the protein is both the drug and the scaffold. Upon subcutaneous injection, their progressive disintegration results in the sustained release of the building block polypeptides, which reach the bloodstream for systemic distribution and subsequent biological effects. Such entities are easily fabricated in vitro by Zn-assisted cross-molecular coordination of histidine residues. Using cationic Zn for the assembly of selected pure protein species and in the absence of any heterologous holding material, these granules are expected to be nontoxic and therefore adequate for different clinical uses. However, such presumed biosafety has not been so far confirmed and the potential protein dosage threshold not probed yet. By selecting the receptor binding domain (RBD) from the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein as a model protein and using a mouse lab model, we have explored the toxicity of RBD-made secretory granules at increasing doses up to ∼100 mg/kg of animal weight. By monitoring body weight and biochemical blood markers and through the histological scrutiny of main tissues and organs, we have not observed systemic toxicity. Otherwise, the bioavailability of the material was demonstrated by the induction of specific antibody responses. The presented data confirm the intrinsic biosafety of artificial secretory granules made by recombinant proteins and prompt their further clinical development as self-contained and dynamic protein reservoirs

A high-throughput yeast approach to characterize aquaporin permeabilities: Profiling the Arabidopsis PIP aquaporin sub-family

PUBLISHED 19 January 2023Introduction: Engineering membrane transporters to achieve desired functionality is reliant on availability of experimental data informing structure-function relationships and intelligent design. Plant aquaporin (AQP) isoforms are capable of transporting diverse substrates such as signaling molecules, nutrients, metalloids, and gases, as well as water. AQPs can act as multifunctional channels and their transport function is reliant on many factors, with few studies having assessed transport function of specific isoforms for multiple substrates. Methods: High-throughput yeast assays were developed to screen for transport function of plant AQPs, providing a platform for fast data generation and cataloguing of substrate transport profiles.We applied our high-throughput growth-based yeast assays to screen all 13 Arabidopsis PIPs (AtPIPs) for transport of water and several neutral solutes: hydrogen peroxide (H2O2), boric acid (BA), and urea. Sodium (Na+) transport was assessed using elemental analysis techniques. Results: All AtPIPs facilitated water and H2O2 transport, although their growth phenotypes varied, and none were candidates for urea transport. For BA and Na+ transport, AtPIP2;2 and AtPIP2;7 were the top candidates, with yeast expressing these isoforms having the most pronounced toxicity response to BA exposure and accumulating the highest amounts of Na+. Linking putative AtPIP isoform substrate transport profiles with phylogenetics and gene expression data, enabled us to align possible substrate preferences with known and hypothesized biological roles of AtPIPs. Discussion: This testing framework enables efficient cataloguing of putative transport functionality of diverse AQPs at a scale that can help accelerate our understanding of AQPbiology through big data approaches (e.g.association studies).The principles of the individual assays could be further adapted to test additional substrates. Data generated from this framework could inform future testing of AQP physiological roles, and address knowledge gaps in structure-function relationships to improve engineering efforts.Michael Groszmann, Annamaria De Rosa, Weihua Chen, Jiaen Qiu, Samantha A. McGaughey, Caitlin S. Byrt and John R. Evan

Validity of numerical trajectories in the synchronization transition of complex systems

We investigate the relationship between the loss of synchronization and the onset of shadowing breakdown {\it via} unstable dimension variability in complex systems. In the neighborhood of the critical transition to strongly non-hyperbolic behavior, the system undergoes on-off intermittency with respect to the synchronization state. There are potentially severe consequences of these facts on the validity of the computer-generated trajectories obtained from dynamical systems whose synchronization manifolds share the same non-hyperbolic properties.Comment: 4 pages, 4 figure

Hydrodynamic theory for granular gases

A granular gas subjected to a permanent injection of energy is described by means of hydrodynamic equations derived from a moment expansion method. The method uses as reference function not a Maxwellian distribution $f_{\sf M}$ but a distribution $f_0 = \Phi f_{\sf M}$, such that $\Phi$ adds a fourth cumulant $\kappa$ to the velocity distribution. The formalism is applied to a stationary conductive case showing that the theory fits extraordinarily well the results coming from our molecular dynamic simulations once we determine $\kappa$ as a function of the inelasticity of the particle-particle collisions. The shape of $\kappa$ is independent of the size $N$ of the system.Comment: 10 pages, 9 figures, more about our research in http://www.cec.uchile.cl/cinetica