The role of hydrogen bonding in the dehydration of bioalcohols in hydrophobic pervaporation membranes

The dehydration of bioalcohols is considered one of the major factors contributing to the cost of biofuel production. In this study, liquid phase separation of water from methanol and ethanol in a siliceous MFI pervaporation membrane was studied by performing concentration gradient driven molecular dynamic (CGD-MD) simulations. CGD-MD simulations work by imposing a higher concentration in the feed side and a lower concentration in the permeate side of the membrane. This creates a concentration gradient across the membrane that facilitates the diffusion of molecules from the feed to the permeate side, mimicking the experimental pervaporation membrane set up. Fluxes of methanol, ethanol and water were calculated in single component permeation simulations and in equimolar methanol–water and ethanol–water mixture separation simulations. It was found that water formed hydrogen bonds with the silanol (Si-OH) groups on the external surface of the MFI and did not enter the membrane in the single component permeation simulation. While this may suggest that MFI can be used to effectively dehydrate bioalcohols, our simulations showed that water permeated through the MFI membrane when it was in a mixture with either methanol or ethanol. Furthermore, in the alcohol-water mixture simulations, the fluxes of methanol and ethanol were significantly lower than that of expected based on their single component fluxes. A detailed analysis of hydrogen bonding in the alcohol-water mixture separation simulations revealed that water preferred making hydrogen bonds with methanol and ethanol rather than with the silanol groups. This resulted in drifting of water molecules along with permeating alcohol molecules in to the MFI membrane in mixture simulations, while slowing the permeation of methanol and ethanol fluxes. The hydrogen bonding between water and alcohol molecules indicates that it may not be possible to achieve complete alcohol selectivity even if defect-free membranes were manufactured; however, our findings also hint at the possibility of functionalizing membrane surfaces with chemical groups that will overcome water-alcohol hydrogen bonding and retain water molecules in order to approach complete selectivity

SL(2,R)SL(2,R) symmetry and quasi-normal modes in the BTZ black hole

With the help of two new intrinsic tensor fields associated with the $SL(2,R)$ quadratic Casimir of Killing fields, we uncover the $SL(2,R)$ symmetry satisfied by the solutions to the equations of motion for various fields in the BTZ black hole in a uniform way by performing tensor and spinor analysis without resorting to any specific coordinate system. Then with the standard algebraic method developed recently, we determine the quasi-normal modes for various fields in the BTZ black hole. As a result, the quasi-normal modes are given by the infinite tower of descendants of the chiral highest weight mode, which is in good agreement with the previous analytic result obtained by exactly solving equations of motion instead.Comment: JHEP style, 1+13 pages, version to appear in JHE

Chemical characterization of passion fruit (Passiflora edulis f. flavicarpa) seeds

The aim of this study was to determine the chemical characteristics of passion fruit seeds and their oil for possible use in human food and reduction of organic waste from fruit industrialization. Passion fruit seeds were analyzed for moisture, lipids, proteins, ash, fibers, titratable acidity, pH, soluble solids and antioxidant activity. The oil was characterized for parameters such as acid value, saponification, iodine and peroxide. The content of oil extracted demonstrates that it has good potential for  industrial utilization. According to analyses, the oil has characteristics similar to conventional edible oils such as soybean, and may be a new source of human consumption. Passion fruit seeds have high nutritional value, proving to be a promising product, mainly because it contains  significant amounts of proteinase. Therefore, passion fruit seeds and their oil should be used as raw material in the food, chemical and pharmaceutical industry, as they have beneficial features.Key words: Industrial utilization, characterization, by-products

Assistência pré-natal à adolescente e os atributos da Atenção Primária à Saúde

OBJECTIVE: evaluate prenatal care for adolescents in health units, in accordance with the attributes of Primary Health Care (PHC) guidelines. METHOD: quantitative study conducted with health professionals, using the Primary Care Assessment Tool-Brazil to assess the presence and extent of PHC attributes. RESULTS: for all the participating units, the attribute Access scored =6.6; the attributes Longitudinality, Coordination (integration of care), Coordination (information systems) and Integrality scored =6.6, and the Essential Score =6.6. Comparing basic units with family health units, the attribute scores were equally distributed; Accessibility scored =6.6, the others attributes scored =6.6; however, in the basic units, the Essential Score was =6.6 and, in the family health units, =6.6. CONCLUSION: expanding the coverage of family health units and the training of professionals can be considered strategies to qualify health care.OBJETIVO: evaluar la atención prenatal a las adolescentes en unidades de salud, según los atributos de la Atención Primaria a la Salud. MÉTODO: estudio de abordaje cuantitativo, realizado con profesionales de la salud, utilizando el instrumento Primary Care Assessment Tool-Brasil para analizar la presencia y extensión de los atributos vinculados a la APS en las unidades de salud. RESULTADOS: para todas las unidades participantes, el atributo Acceso obtuvo un puntaje =6,6; los atributos Longitudinalidad, Coordinación (integración de cuidados), Coordinación (sistemas de información) e Integralidad obtuvieron puntajes =6,6 y el Puntaje Esencial fue =6,6. Comparando las unidades básicas de salud y las unidades de salud de la familia, los puntajes están igualmente distribuidos: Accesibilidad =6,6 y los demás atributos con puntajes =6,6; sin embargo, el puntaje Esencial en las unidades básicas fue =6,6 y el de las unidades de salud de la familia fue =6,6. CONCLUSIÓN: la ampliación de la cobertura de las unidades de salud de la familia y la capacitación profesional pueden ser estrategias para calificar la atención a la salud.OBJETIVO: avaliar a atenção pré-natal às adolescentes em unidades de saúde, segundo os atributos da Atenção Primária à Saúde. MÉTODO: estudo de abordagem quantitativa, realizado com profissionais de saúde, utilizando-se o instrumento Primary Care Assessment Tool-Brasil, para analisar a presença e extensão dos atributos. RESULTADOS: para todas as unidades participantes, o atributo acesso obteve escore =6,6; os atributos longitudinalidade, coordenação (integração de cuidados), coordenação (sistemas de informação) e integralidade obtiveram escores =6,6 e escore essencial =6,6. Comparando-se as unidades básicas e as unidades de saúde da família, os escores estão igualmente distribuídos: acessibilidade: =6,6 e os demais atributos com escores =6,6, no entanto, o escore essencial nas unidades básicas foi =6,6 e nas unidades de saúde da família foi =6,6. CONCLUSÃO: a ampliação da cobertura das unidades de saúde da família e a capacitação profissional podem ser estratégias para qualificar a atenção à saúde

Mathematics in Modern Immunology

Mathematical and statistical methods enable multi-disciplinary approaches that catalyse discovery. Together with experimental methods, they identify key hypotheses, de ne measurable observables and reconcile disparate results. We collect a representative sample of studies in cell biology that illustrate the benefits of modelling-experimental collaborations and that have proven valuable or even ground-breaking. We conclude that it is possible to nd excellent examples of synergy between mathematical modelling and experiment in Immunology, which have brought signi cant insight that would not be available without these collaborations, but that much remains to be discovered

On the General Kerr/CFT Correspondence in Arbitrary Dimensions

We study conformal symmetries on the horizon of a general stationary and axisymmetric black hole. We find that there exist physically reasonable boundary conditions that uniquely determine a set of symmetry generators, which form one copy of the Virasoro algebra. For extremal black holes, Cardy's formula reproduces exactly the Bekenstein-Hawking entropy.Comment: 17 page

Chemical physics: The standing of a mature discipline

It is always promising and enticing to start a new editorial task in the scientific arena and the launch of the Chemistry Central Journal is no exception. The different thematic sections making up this journal are quite representative of the whole chemistry enterprise. However, one of them has a special relevance. In fact, Chemical Physics (CP) is the most general and it embodies a wide diversity of issues. Of particular importance at the launch of this groundbreaking new journal is the confidence of the Section Editor in BioMed Central (owners of Chemistry Central) as publishers, and from Chemistry Central to its Editorial Board. I feel deeply grateful for this new assignment and I hope to be able to perform a thorough job in editing this section. Below, I make my request to you as potential authors and reviewers

Categorical Dimensions of Human Odor Descriptor Space Revealed by Non-Negative Matrix Factorization

In contrast to most other sensory modalities, the basic perceptual dimensions of olfaction remain unclear. Here, we use non-negative matrix factorization (NMF) – a dimensionality reduction technique – to uncover structure in a panel of odor profiles, with each odor defined as a point in multi-dimensional descriptor space. The properties of NMF are favorable for the analysis of such lexical and perceptual data, and lead to a high-dimensional account of odor space. We further provide evidence that odor dimensions apply categorically. That is, odor space is not occupied homogenously, but rather in a discrete and intrinsically clustered manner. We discuss the potential implications of these results for the neural coding of odors, as well as for developing classifiers on larger datasets that may be useful for predicting perceptual qualities from chemical structures