Concentrated protein solutions investigated using acoustic levitation and small-angle X-ray scattering

An acoustically levitated droplet has been used to collect synchrotron SAXS data on human serum albumin protein solutions up to a protein concentration of 400 mg ml−1. A careful selection of experiments allows for fast data collection of a large amount of data, spanning a protein concentration/solvent concentration space with limited sample consumption (down to 3 µL per experiment) and few measurements. The data analysis shows data of high quality that are reproducible and comparable with data from standard flow-through capillary-based experiments. Furthermore, using this methodology, it is possible to achieve concentrations that would not be accessible by conventional cells. The protein concentration and ionic strength parameter space diagram may be covered easily and the amount of protein sample is significantly reduced (by a factor of 100 in this work). Used in routine measurements, the benefits in terms of protein cost and time spent are very significant.

Human beings as islands of stability: Monitoring body states using breath profiles

By checking the reproducibility of conventional mid-infrared Fourier spectroscopy of human breath in a small test study (15 individuals), we found that a set of volatile organic compounds (VOC) of the individual breath samples remains reproducible at least for 18 months. This set forms a unique individual’s “island of stability” (IOS) in a multidimensional VOC concentration space. The IOS stability can simultaneously be affected by various life effects as well as the onset of a disease. Reflecting the body state, they both should have different characteristics. Namely, they could be distinguished by different temporal profiles: In the case of life effects (beverage intake, physical or mental exercises, smoking etc.), there is a non-monotonic shift of the IOS position with the return to the steady state, whereas a progressing disease corresponds to a monotonic IOS shift. As a first step of proving these dependencies, we studied various life effects with the focus on the strength and characteristic time of the IOS shift. In general, our results support homeostasis on a long time scale of months, allostasis on scales of hours to weeks or until smoke quitting for smokers, as well as resilience in the case of recovery from a disease.

Stretch-induced complexation reaction between poly(vinyl alcohol) and iodine: an in situ synchrotron radiation small- and wide-angle X-ray scattering study

A morphological and structural phase diagram of PVA and iodine is constructed in the strain–iodine concentration space.

Centralidade dos serviços de saúde na zona leste de Teresina (PI): uma análise de sua produção espacial / Centrality of the health services in the East region of Teresina, PI: an analysis of its space production

<p>Compreende-se a centralidade intraurbana como especializações funcionais de algumas frações espaciais da cidade que se singularizam a partir da concentração e geração de fluxos permanentes de pessoas e mercadorias. Nessa direção, a centralidade dos serviços de saúde de Teresina tem seu marco inicial com a instalação do Hospital Getúlio Vargas (1941) no centro histórico da cidade. Desde então, diversos hospitais, clínicas, laboratórios e atividades correlatas aí se instalaram, o que lhes configura como o espaço de maior concentração destes na cidade. Mas, a partir dos anos 2000 inicia-se um processo de descentralização dos serviços de saúde para outros espaços citadinos, notadamente para os bairros mais centrais da zona Leste. Nesse sentido, objetiva-se analisar a produção espacial da centralidade dos serviços de saúde na zona Leste de Teresina, pautado em depoimentos de profissionais e empreendedores dos bairros Fátima, Jóquei e São Cristóvão que lidam com os referidos serviços. Argumenta-se que a constituição dessa nova centralidade dos serviços de saúde de Teresina baseia-se na busca do segmento de renda alta da cidade, o qual exige serviços exclusivos e próximos aos seus locais de moradia ou de mais fácil acessibilidade quando comparados aos encontrados no centro principal.</p><p><strong>Palavras-chaves</strong>: Centralidade. Serviços de Saúde. Zona Leste de Teresina.</p><p><strong>Abstract</strong></p><p>The intraurban centrality is understood as the functional specializations of some space fractions of the city that singularize from the concentration of people and goods permanent flux generation. In this direction, the centrality of the health services of Teresina has its beginning with the installation of Getúlio Vargas Hospital (1941) in the historic center of the city. Since then, several hospitals, laboratories and related activities have been installed, which is configured as their greatest concentration space of this city. But, from 2000, a process of decentralization of health services has begun to other city places, mainly to the more central districts of the East region. This way, it is aimed to analyze the space production of the centrality of the health services in the least region of Teresina, based on the testimony of the professionals and entrepreneurs of the districts of Fátima, Jóquei and São Cristóvão that deal with such services. It argues that the constitution of this new centrality of health services in Teresina is based on the search for the high income population of the city, which demands exclusive services and near their living places or of easier accessibility when compared to the ones found in the main downtown. </p><p><strong>Keywords</strong>: Centrality. Health Services. East Region of Teresina.</p>

THE STRATEGY OF STUDYING THREE-LIQUID PHASE EQUILIBRIA IN THE CONCENTRATION SPACE OF QUATERNARY MIXTURES

When separating multicomponent heterogeneous mixtures in units consisting of a distillation column and a decanter, a fundamental question is the location of phase separation regions with different numbers of liquid phases in the concentration simplex. A solution of this issue is based on data on the vapor-liquid and liquid-liquid equilibria of the mixture and its components, as well as on the general laws of the formation of the topological structure of phase separation areas. A strategy of studying the three-liquid phase equilibrium area in quaternary mixtures is proposed. The strategy is based on the formula of a topological invariant of the separation region and on the mathematical concept of centroid - the intersection point of three medians. The presence of threeliquid phase areas of separation of open and closed types is shown. They differ in the absence (presence) of region of degeneracy via the critical node.

Varing chemical equilibrium gives kinetic parameters

We are interested in finding the kinetic parameters of a chemical reaction. Previous methods for finding these parameters rely on the dynamic behaviour of the system. This means that the methods are time-sensitive and often rely on non-linear curve fitting. In the same manner as previous techniques, we consider the concentrations of chemicals in a reaction. However, we investigate the static behaviour of the reaction at dynamic equilibrium, or steady state. Here too, the chemical concentrations depend on the kinetic parameters of the reaction. In an open reaction, the static concentrations also depends on the rate of input of the source of reacting chemical. Controlling this input rate slides the steady state along a curve in concentration space. This curve is determined by the kinetic parameters. The plane of this curve is sufficient to find the kinetic parameters. The new method we propose uses only the steady state concentration values to determine the kinetic parameters of the reaction. These values are constant once dynamic equilibrium is achieved, and so can be read accurately. Readings can be repeated readily to reduce error. Thus this new technique is simple and could produce accurate kinetic parameter estimates.

Mixing by random stirring in confined mixtures

We study the relaxation of initially segregated scalar mixtures in randomly stirred media, aiming to describe the overall concentration distribution of the mixture, its shape and rate of deformation as it evolves towards uniformity. A stirred scalar mixture can be viewed as a collection of stretched sheets, possibly interacting with each other. We consider a situation in which the interaction between the sheets is enforced by confinement and is the key factor ruling its evolution. It consists of following a mixture relaxing towards uniformity around a fixed average concentration while flowing along a constant cross-section channel. The interaction between the sheets is found to be of a random addition nature in concentration space, leading to concentration distributions that are stable by self-convolution. The resulting scalar field is naturally coarsened at a scale much larger than the dissipation scale. Consequences on the mixture entropy and scalar rate of dissipation are also examined.