Chemical bonding effects in Sc compounds studied using X-ray absorption and X-ray photoelectron spectroscopies

Advances on understanding the nature of the chemical bonding and electron correlation effects during the X-ray absorption process in ionic–covalent metal complexes has been achieved for most of the transition elements, except for scandium, due to the lack of a systematic series of spectroscopic reference spectra and the shortage of standard crystallographic data on scandium compounds. To close the gap, the chemical bonding effects in eight Sc compounds are studied using X-ray absorption spectroscopy (XAS) at Sc K and L2,3 absorption edges and X-ray photoelectron spectroscopy (XPS). Indeed, the fine structure of the XAS Sc K edge reflects the chemical sp3-like bond formed between scandium and the ligand while the L2,3 edge and the pre-edge features of the K-edge provide a direct insight into the crystal field parameters at the Sc site in the coordination compound. The XPS data provide the information on binding energies of the core electrons involved in the electron transitions caused by the absorption of high energy X-rays. XAS and XPS complement each other by accessing the information on Sc structure on bulk and the surface. Herein, comprehensive information on the electronic structure of well-known crystalline materials based on Sc is given with spectroscopic fingerprints X-ray data. This will help to predict the formation of chemical bonds in the unknown components via the systematic evaluation of the available spectroscopic fingerprints

Article hydrogen separation performance of UiO-66-NH2_{2} membranes grown via liquid-phase epitaxy layer-by-layer deposition and one-pot synthesis

The quality assurance of hydrogen fuel for mobile applications is assessed by the guidelines and directives given in the European and international standards. However, the presence of impurities in the hydrogen fuel, in particular nitrogen, water, and oxygen, is experienced in several refueling stations. Within this work, metal-organic framework (MOF)-based membranes are investigated as a fine-purification stage of the hydrogen fuel. Three H$_{2}$2/N$_{2}$ concentrations have been used to analyze the separation factor of UiO-66-NH$_{2}$ membranes prepared using the layer-by-layer (LBL) and the one-pot (OP) synthesis methods. It is shown that the separation factor for an equimolar ratio is 14.4% higher for the LBL sample compared to the OP membrane, suggesting a higher orientation and continuity of the LBL surface-supported metal-organic framework (SURMOF). Using an equimolar ratio of H$_{2}$/N$_{2}$, it is shown that selective separation of hydrogen over nitrogen occurs with a separation factor of 3.02 and 2.64 for the SURMOF and MOF membrane, respectively. To the best of our knowledge, this is the highest reported performance for a single-phase UiO-66-NH$_{2}$ membrane. For higher hydrogen concentrations, the separation factor decreases due to reduced interactions between pore walls and N$_{2}$ molecules

Synthesis and Properties of Magnesium Tetrahydroborate, Mg(BH4)2

Mg(BH4)2 is one of the few complex hydrides which have the potential to meet the requirements for hydrogen storage materials, because it contains 14.9 mass% H and has suitable thermodynamic properties. It has not been investigated for hydrogen storage applications yet. In this study, several ways to synthesize solvated and desolvated magnesium tetrahydroborate by wet chemical and mechanochemical methods were tested and compared. A direct synthesis by a reaction of MgH2 with aminoboranes yields magnesium tetrahydroborate quantitatively and in pure form. The method is also applicable to the synthesis of other tetrahydroborates. The products were characterized by elemental analysis, in situ X-ray diffraction (XRD), infrared spectroscopy (FTIR), and thermal analysis methods, such as thermogravimetric analysis (TGA-DSC) and high-pressure calorimetry under a hydrogen atmosphere (HP-DSC)

Hydrogen Road Transport Analysis in the Energy System: A Case Study for Germany through 2050

Carbon-free transportation is envisaged by means of fuel cell electric vehicles (FCEV) propelled by hydrogen that originates from renewably electricity. However, there is a spatial and temporal gap in the production and demand of hydrogen. Therefore, hydrogen storage and transport remain key challenges for sustainable transportation with FCEVs. In this study, we propose a method for calculating a spatially resolved highway routing model for Germany to transport hydrogen by truck from the 15 production locations (source) to the 9683 fueling stations (sink) required by 2050. We consider herein three different storage modes, namely compressed gaseous hydrogen (CGH2), liquid hydrogen (LH2) and liquid organic hydrogen carriers (LOHC). The model applies Dijkstra’s shortest path algorithm for all available source-sink connections prior to optimizing the supply. By creating a detailed routing result for each source-sink connection, a detour factor is introduced for “first and last mile” transportation. The average detour factor of 1.32 is shown to be necessary for the German highway grid. Thereafter, the related costs, transportation time and travelled distances are calculated and compared for the examined storage modes. The overall transportation cost result for compressed gaseous hydrogen is 2.69 €/kgH2, 0.73 €/kgH2 for liquid hydrogen, and 0.99 €/kgH2 for LOHCs. While liquid hydrogen appears to be the most cost-efficient mode, with the integration of the supply chain costs, compressed gaseous hydrogen is more convenient for minimal source-sink distances, while liquid hydrogen would be suitable for distances greater than 130 km

Can human biomonitoring studies contribute to improve public health decisions?

Abstract publicado em: J Clin Toxicol 2017, 7:3 (suppl)., 66. Doi: 10.4172/2161-0495-C1-025-005: Disponível em: https://www.omicsonline.org/conference-proceedings/2161-0495-C1-025-005.pdfStatement of the Problem: Our previous work has shown the presence of the hazardous chemicals within a complex mixture of contaminants (e.g., metals, pesticides, polycyclic aromatic hydrocarbons) trapped in sediments of a Portuguese estuary. In that case-study, an epidemiological survey confirmed the exposure of the local population mainly through food chain, suggesting the need of a biomonitoring study that includes the quantification of contaminants in biological fluids as well as biomarkers of early biological effects (e.g., biochemical, genetic and omics-based endpoints) in the target population. Recognizing the knowledge gap between exposure to hazardous substances and health outcomes, not only in Portuguese population, but also throughout Europe, the project European Human Biomonitoring Initiative (HBM4EU) has just started, with the overarching goal of generating knowledge towards the safe management of chemicals. Methodology & Theoretical Orientation: Human biomonitoring will be used to understand the human exposure to chemicals and resulting health impacts. The first steps rely on harmonizing procedures for human biomonitoring across countries, to provide policy makers with comparable data on human internal exposure to chemicals and mixtures of chemicals at EU level. Then, linking data on internal exposure with the hazardous chemicals, will allow to aggregate external exposure and identifying exposure pathways and upstream sources. Conclusion & Significance: By generating scientific evidence on the causal links between human exposure to chemicals and negative health outcomes, an evidence-base will be established to allow the use of human biomonitoring in chemical risk assessment methodologies to data. The risk management and communication with stakeholders and policy makers will ensure that results are applied in the design of new regulations for chemicals and for supporting public health protection policies.HBM4EU project, Grant agreement No: 733032info:eu-repo/semantics/publishedVersio

Atividades de monitoria por meio de plataformas virtuais em tempos de pandemia: um relato de experiência

RESUMO: As atividades de monitoria, amplamente desenvolvidas no meio universitário brasileiro, podem ser definidas como um processo por meio do qual discentes-monitores auxiliam seus colegas de curso no processo de ensino-aprendizagem, sob orientação direta de um docente. O objetivo do presente trabalho consiste em relatar as experiências dos monitores da disciplina de Medicina de Família e Comunidade de uma instituição de ensino superior privada, na cidade de Anápolis, Goiás, que assistem os alunos do sexto período do curso. As atividades desenvolvidas foram realizadas por meio de plataformas virtuais, devido ao isolamento social requerido durante a pandemia pelo novo coronavírus (COVID-19). Notou-se, por meio dos relatos dos monitores, assim como pela avaliação dos discentes assistidos, que, apesar de realizado à distância, o ensino de monitoria foi de grande importância para o esclarecimento das atividades realizadas, além de ter possuído caráter bastante satisfatório. A monitoria, desenvolvida por meio de plataformas virtuais, mostrou-se, assim, de fundamental importância para o processo ensino-aprendizagem dos discentes-monitores e dos acadêmicos auxiliados. &nbsp

Riscos cardiovasculares em idosos hipertensos

RESUMO: Este estudo procura avaliar a incidência de doenças cardiovasculares (DCV) em idosos hipertensos, por meio da análise conjunta de artigos que abordam a temática. Caracteriza-se por um resumo expandido em que foram considerados estudos que correlacionam a presença da hipertensão ao aparecimento de DCV, com foco na terceira idade da população brasileira. A partir da discussão dos resultados, percebeu-se a indispensabilidade do acompanhamento realizado por equipes multidisciplinares de atenção básica para a promoção e prevenção de saúde no grupo de idosos em estudo. Conclui-se, então, que é necessária a criação de estratégias que visem diminuir os riscos provenientes da hipertensão não controlada.Palavras-chave:Idosos. Hipertensão. Riscos cardiovasculares. Prevenção

Ansiedade, depressão e ideação suicida entre estudantes de medicina: uma revisão de literatura

Conceito fundamental e intrínseco à prática médica psiquiátrica, a saúde mental pode ser definida como termo de significado substancialmente subjetivo, com vistas ao nível de qualidade de vida emocional e cognitiva. Em meio a um ambiente de constante exposição ao estresse, tem-se observado, entre os estudantes de medicina, a ocorrência de um grande número de afecções psiquiátricas, entre as quais se destacam a ansiedade, a depressão e a ideação suicida. O presente estudo tem, por objetivo, analisar as diferentes modalidades de transtornos mentais entre estes estudantes, relacionandoos com seus respectivos fatores predisponentes. Metodologicamente, foi realizado um estudo descritivo, baseado em uma revisão de literatura, com o uso de vinte e quatro artigos publicados entre os anos de 2008 e 2019, que abrangem os critérios epidemiológicos, clínicos e preventivos das afecções em questão. Conclui-se, desta maneira, que a grande exposição a fontes estressoras – sejam elas internas ou externas –, constantes no meio acadêmico médico, são fundamentais para o desenvolvimento dos transtornos mentais aqui expostos. É possível, porém, que, por meio de ações interventivas, o número de desfechos potencialmente fatais e desfavoráveis sejam evitados, configurando os transtornos em questão como preveníveis e passíveis de identificação e tratamento