Bouncing off the walls : the influence of gas-kinetic and van der Waals effects in drop impact

A model is developed for liquid drop impact on a solid surface that captures the thin film gas flow beneath the drop, even when the film’s thickness is below the mean free path in the gas so that gas kinetic effects (GKE) are important. Simulation results agree with experiments, with the impact speed threshold between bouncing and wetting reproduced to within 5 least 50 mapped and provides experimentally verifiable predictions. There are two principal modes of contact leading to wetting and both are associated with a van der Waals driven instability of the film

Анализ параметров активной фазированной антенной решетки радиотелескопа ГУРТ

Представлены методика расчета и результаты численного анализа параметров активной фазированной антенной решетки (АФАР) Гигантского украинского радиотелескопа (ГУРТ) декаметрового и метрового диапазонов волн, который сооружается в настоящее время вблизи г. Харькова на территории Радиоастрономической обсерватории им. С. Я. Брауде Радиоастрономического института Национальной академии наук Украины. Методика базируется на матричной теории антенных решеток, сочетающей в себе электродинамический подход к анализу решетки излучателей с методами теории многополюсников СВЧ для описания фидерной схемы АФАР. Приведены и проанализированы результаты численного расчета эффективной площади АФАР и коэффициента передачи, который в случае пассивной ФАР ассоциируется с КПД, в широком секторе сканирования луча в диапазоне частот 10- 80 МГц.Надаються методика розрахунку та результати числового аналізу параметрів активної фазованої антенної решітки (АФАР) Гігантського українського радіотелескопу (ГУРТ) декаметрового та метрового діапазонів хвиль, що наразі споруджується поблизу м. Харкова на території Радіоастрономічної обсерваторії ім. С. Я. Брауде Радіоастрономічного інституту Національної академії наук України. Методика базується на матричній теорії антенних решіток, що поєднує електродинамічний підхід до аналізу решітки випромінювачів з методами теорії багатополюсників НВЧ для опису фідерної схеми АФАР. Наведені та проаналізовані результати числового розрахунку ефективної площі АФАР та коефіцієнту передачі, що в разі пасивної ФАР асоціюється з ККД, у широкому секторі сканування променя в діапазоні частот 10 - 80 МГц.The calculation technique results of numerical analysis of parameters of active phased antenna array (APAA) of the Giant Ukrainian Radio Telescope (GURT) of decameter and meter wavelengths which is being built now nearby Kharkiv at the area of S. Ya. Braude Radio Astronomy Observatory of the Institute of Radio Astronomy of the National Academy of Sciences of Ukraine are presented. The technique is based on the matrix theory of antenna arrays which combines an electromagnetic approach to analysis of radiators array with the methods of microwave multiport theory for the APAA feed network description. The results of numerical calculation of the APAA effective area and its gain, which in case of passive array is associated with its efficiency, are given and analyzed for a wide scan range within 10 to 80 MHz

Características del conflicto dependientes de la duración de la estadía en el lugar de trabajo.

The study of conflicts is one of the most dynamic areas of development of psychology, so the article presents a comprehensive and detailed analysis of the concept of conflict as a result of the comparison of the indicators obtained during the study of styles, patterns of behavior in situations of conflict and types of reactions in situations of stress. It was found that the members of the group, with a long stay in the workplace, have constructive models to face stressful situations, as well as that the types of reactions to conflict situations such as negativity and irritability were more pronounced. The results obtained can be used in the psychology of work, practical psychology, sociology, as well as for the theoretical development of this topic.El estudio de los conflictos es una de las áreas de desarrollo más dinámico de la psicología, por lo que el artículo presenta un análisis exhaustivo y detallado del concepto de conflicto como resultado de la comparación de los indicadores obtenidos durante el estudio de estilos, patrones de comportamiento en situaciones de conflicto y tipos de reacciones en situaciones de estrés. Se encontró que los miembros del grupo, con una larga permanencia en el lugar de trabajo, poseen modelos constructivos para enfrentar situaciones estresantes, así como que los tipos de reacciones a situaciones de conflicto como la negatividad y la irritabilidad eran más pronunciadas. Los resultados obtenidos se pueden utilizar en la psicología del trabajo, la psicología práctica, la sociología, así como para el desarrollo teórico de este tema.&nbsp

Droplet Reactors with Bioluminescent Enzymes for Real-Time Water Pollution Monitoring

Early detection of pollutants in wastewater, water coming out of treatment facilities, drinking water, and water for agricultural needs is a challenging problem. Effective water quality monitoring requires development of new methods for express detection of pollutants. Enzymes from bioluminescent bacteria can be used for the development of new express enzyme-based bioassay systems. This work demonstrates, for the first time, a microfluidic chip to generate emulsion droplets containing two enzymes of the bacterial bioluminescent system (luciferase and NAD(P)H:FMN-oxidoreductase) with reaction substrates. The developed chip generated “water-in-oil” emulsion droplets with a volume of 0.1 μL and a frequency of up to 12 droplets per second. A portable photomultiplier tube (PMT) was used to measure the bioluminescent signal in each individual droplet; the signal-to-noise ratio was 3000/1. The intensity of luminescence in droplets depended on the concentration of copper ions. The limit of detection (LOD) for copper sulfate was 1 mg/L. We showed that bioluminescent enzymatic reactions can be carried out in droplet reactors that can be applied for online monitoring of water quality. Thus, the suggested method of biological measurements has a good perspective for biosensing in general

OmpC and OmpF Outer Membrane Proteins of Escherichia coli and Salmonella enterica Form Bona Fide Amyloids

Outer membrane proteins (Omps) of Gram-negative bacteria represent porins involved in a wide range of virulence- and pathogenesis-related cellular processes, including transport, adhesion, penetration, and the colonization of host tissues. Most outer membrane porins share a specific spatial structure called the β-barrel that provides their structural integrity within the membrane lipid bilayer. Recent data suggest that outer membrane proteins from several bacterial species are able to adopt the amyloid state alternative to their β-barrel structure. Amyloids are protein fibrils with a specific spatial structure called the cross-β that gives them an unusual resistance to different physicochemical influences. Various bacterial amyloids are known to be involved in host-pathogen and host-symbiont interactions and contribute to colonization of host tissues. Such an ability of outer membrane porins to adopt amyloid state might represent an important mechanism of bacterial virulence. In this work, we investigated the amyloid properties of the OmpC and OmpF porins from two species belonging to Enterobacteriaceae family, Escherichia coli, and Salmonella enterica. We demonstrated that OmpC and OmpF of E. coli and S. enterica form toxic fibrillar aggregates in vitro. These aggregates exhibit birefringence upon binding Congo Red dye and show characteristic reflections under X-ray diffraction. Thus, we confirmed amyloid properties for OmpC of E. coli and demonstrated bona fide amyloid properties for three novel proteins: OmpC of S. enterica and OmpF of E. coli and S. enterica in vitro. All four studied porins were shown to form amyloid fibrils at the surface of E. coli cells in the curli-dependent amyloid generator system. Moreover, we found that overexpression of recombinant OmpC and OmpF in the E. coli BL21 strain leads to the formation of detergent- and protease-resistant amyloid-like aggregates and enhances the birefringence of bacterial cultures stained with Congo Red. We also detected detergent- and protease-resistant aggregates comprising OmpC and OmpF in S. enterica culture. These data are important in the context of understanding the structural dualism of Omps and its relation to pathogenesis

β-Barrels and Amyloids: Structural Transitions, Biological Functions, and Pathogenesis

Insoluble protein aggregates with fibrillar morphology called amyloids and β-barrel proteins both share a β-sheet-rich structure. Correctly folded β-barrel proteins can not only function in monomeric (dimeric) form, but also tend to interact with one another—followed, in several cases, by formation of higher order oligomers or even aggregates. In recent years, findings proving that β-barrel proteins can adopt cross-β amyloid folds have emerged. Different β-barrel proteins were shown to form amyloid fibrils in vitro. The formation of functional amyloids in vivo by β-barrel proteins for which the amyloid state is native was also discovered. In particular, several prokaryotic and eukaryotic proteins with β-barrel domains were demonstrated to form amyloids in vivo, where they participate in interspecies interactions and nutrient storage, respectively. According to recent observations, despite the variety of primary structures of amyloid-forming proteins, most of them can adopt a conformational state with the β-barrel topology. This state can be intermediate on the pathway of fibrillogenesis (“on-pathway state”), or can be formed as a result of an alternative assembly of partially unfolded monomers (“off-pathway state”). The β-barrel oligomers formed by amyloid proteins possess toxicity, and are likely to be involved in the development of amyloidoses, thus representing promising targets for potential therapy of these incurable diseases. Considering rapidly growing discoveries of the amyloid-forming β-barrels, we may suggest that their real number and diversity of functions are significantly higher than identified to date, and represent only “the tip of the iceberg”. Here, we summarize the data on the amyloid-forming β-barrel proteins, their physicochemical properties, and their biological functions, and discuss probable means and consequences of the amyloidogenesis of these proteins, along with structural relationships between these two widespread types of β-folds