Can hydrodynamic contact line paradox be solved by evaporation--condensation?

We investigate a possibility to regularize the hydrodynamic contact line singularity in the configuration of partial wetting (liquid wedge on a solid substrate) via evaporation-condensation, when an inert gas is present in the atmosphere above the liquid. The no-slip condition is imposed at the solid-liquid interface and the system is assumed to be isothermal. The mass exchange dynamics is controlled by vapor diffusion in the inert gas and interfacial kinetic resistance. The coupling between the liquid meniscus curvature and mass exchange is provided by the Kelvin effect. The atmosphere is saturated and the substrate moves at a steady velocity with respect to the liquid wedge. A multi-scale analysis is performed. The liquid dynamics description in the phase-change-controlled microregion and visco-capillary intermediate region is based on the lubrication equations. The vapor diffusion is considered in the gas phase. It is shown that from the mathematical point of view, the phase exchange relieves the contact line singularity. The liquid mass is conserved: evaporation existing on a part of the meniscus and condensation occurring over another part compensate exactly each other. However, numerical estimations carried out for three common fluids (ethanol, water and glycerol) at the ambient conditions show that the characteristic length scales are tiny

Quench cooling under reduced gravity

We report the quench cooling experiments performed with liquid O2 under different levels of gravity simulated with the magnetic gravity compensation. A copper disk is quenched from 270K to 90K. It is found that the cooling time in microgravity is very long in comparison with any other gravity level. This phenomenon is explained by the isolation effect of the gas surrounding the disk. The liquid subcooling is shown to drastically improuve the heat exchange thus reducing the cooling time (about 20 times). The effect of subcooling on the heat transfer is analyzed at different gravity levels. It is shown that such type of experiments cannot be used for the analysis of the critical heat flux (CHF) of the boiling crisis. The minimum heat flux (MHF) of boiling is analyzed instead

Droplet evaporation in one-component fluids: Dynamic van der Waals theory

In a one-component fluid, we investigate evaporation of a small axysymmetric liquid droplet in the partial wetting condition on a heated wall at $T\sim 0.9 T_c$. In the dynamic van der Waals theory (Phys. Rev. E {\bf 75}, 036304 (2007)), we take into account the latent heat transport from liquid to gas upon evaporation. Along the gas-liquid interface, the temperature is nearly equal to the equilibrium coexisting temperature away from the substrate, but it rises sharply to the wall temperature close to the substrate. On an isothermal substrate, evaporation takes place mostly on a narrow interface region near the contact line in a late stage, which is a characteristic feature in one-component fluids.Comment: 6 pages, 6 figure

Experimental analysis and transient numerical simulation of a large diameter pulsating heat pipe in microgravity conditions

A multi-parametric transient numerical simulation of the start-up of a large diameter Pulsating Heat Pipe (PHP) specially designed for future experiments on the International Space Station (ISS) are compared to the results obtained during a parabolic flight campaign supported by the European Space Agency. Since the channel diameter is larger than the capillary limit in normal gravity, such a device behaves as a loop thermosyphon on ground and as a PHP in weightless conditions; therefore, the microgravity environment is mandatory for pulsating mode. Because of a short duration of microgravity during a parabolic flight, the data concerns only the transient start-up behavior of the device. One of the most comprehensive models in the literature, namely the in-house 1-D transient code CASCO (French acronym for Code Avancé de Simulation du Caloduc Oscillant: Advanced PHP Simulation Code in English), has been configured in terms of geometry, topology, material properties and thermal boundary conditions to model the experimental device. The comparison between numerical and experimental results is performed simultaneously on the temporal evolution of multiple parameters: tube wall temperature, pressure and, wherever possible, velocity of liquid plugs, their length and temperature distribution within them. The simulation results agree with the experiment for different input powers. Temperatures are predicted with a maximum deviation of 7%. Pressure variation trend is qualitatively captured as well as the liquid plug velocity, length and temperature distribution. The model also shows the ability of capturing the instant when the fluid pressure begins to oscillate after the heat load is supplied, which is a fundamental information for the correct design of the engineering model that will be tested on the ISS. We also reveal the existence of strong liquid temperature gradients near the ends of liquid plugs both experimentally and by simulation. Finally, a theoretical prediction of the stable functioning of a large diameter PHP in microgravity is given. Results show that the system provided with an input power of 185W should be able to reach the steady state after 1min and maintain a stable operation from then on

IS THERE A NEED TO UNITE TRADITIONAL AND ACADEMIC MEDICINE?

Characteristic features of the eastern tradition of healing and. modern approach to the treatment and. prophylaxis of the diseases are presented in the work. There were discussed the questions concerning the potentialities and. expediency of integration between the given medical systems

Influence of thyrotropic herbal remedy on vascular endothelium and thyroid gland structure in experimental hypothyroidism

The work presents evaluation of influence of plant preparation «Thyreoton-forte» on endothelium of vessels and morphological structure of thyroid gland in experimental hypothyreosis. Experimental hypothyreosis in rats was induced by administration of mercazolilum (10 mg/kg, intragastric introduction) during 28 days. The course administration of «Thyreoton-forte» (50,100 mg/kg, intragastric introduction) decreases the number of circulating endothelial cells (p < 0,05) and normalizes the structure of thyroid gland. Pharmacological effect of «Thyreoton-forte» is provided by protective influence in vascular endothelium and positive action on thyroid gland

Dynamics of the triple contact line on a non-isothermal heater at partial wetting

The dynamics of the triple gas-liquid-solid contact line is analysed for the case where the gas is the saturated vapour corresponding to the liquid, like in the vapour bubble in boiling. It is shown that even small superheating (with respect to the saturation temperature) causes evaporation of the adsorption liquid film and the true triple contact is established. It is shown that the hydrodynamic contact line singularity cannot be relaxed with the Navier slip condition under such circumstances. Augmented with the second derivative slip condition is proposed to be applied. For the partial wetting conditions, a non-stationary contact line problem where the contact line motion is caused by evaporation or condensation is treated in the lubrication approximation in the vicinity of the contact line. High heat fluxes in this region require the transient heat conduction inside the heater to be accounted for. Two 2D problems, those of drop retraction with no phase change and of drop evaporation are solved and analysed as illustrations of the proposed approach

Сombined treatment of squamous-cell anal cancer

Since 1974 chemoradiation scheme proposed by Nigro remains the standard of care for squamous-cell anal cancer in most countries. Improvement of treatment results can be achieved by developing new treatment schemes including different radio- and chemosensitizers.Methods. Results of treatment of 157 T1–4N0–2M0 squamous-cell anal cancer patients, which underwent treatment during 1990–2012 were analyzed. Patients were divided into 3 groups: group A received hyperfractionated radiotherapy (RT) single dose 1.2 Gy bid, total dose 40–44 Gy with 3–5 sessions of local hyperthermia (HT) during treatment; group B had similar RT + HT scheme with addition of chemotherapy (CT) with cisplatin 20 mg/m2 in days 1, 3 weeks 1–4 and bleomycin 15 mg in days 2, 4 weeks 1–4; group C had RT with single dose 2 Gy, same total dose, HT and CT as in group B and additionally received metronidazole 10 g/m2 per rectum in a polymeric composition. Two weeks after 1st treatment stage a second course of RT was carried out 20–24 Gy in 2 Gy fractions in all patient groups.Results. Sphincter-sparing treatment was carried out in 11 (50 %), 71 (80.68 %) and 44 (93.62 %) in groups A, B and C accordingly. Three year overall survival (OS) was 60.0; 82.4; 96.4 %; 3-year disease-free survival (DFS) 36.6; 69.8 and 76.3 % accordingly.Conclusions. In our study combined treatment using radiosensitization allow to improve sphincter preservation rate to 93 %, improve OS and DFS for squamous-cell anal cancer patients

Immunogenic potency of antigenic preparation Bacillus anthracis Sterne 34F₂ and its combination with metal-containing nanocomposites

The article presents the research results of immunogenic potency of antigen preparation Bacillus anthracis Sterne 34F on the guinea pig model. It was found that a single inoculation of this preparation, before the contamination of virulent B. anthracis strain, protects 60-80 % of experimental animals. The metal-containing nanocomposites were used to improve the immunogenicity of this antigen preparation. The combined use of antigenic preparation S-2 with argentogalactomannan increases its immunogenic potency and conduces to the survival of experimental animals. Argentogalactomannan exhibits adjuvant properties enhanced the immunogenic features of the S-2 B. anthracis 34F2 Sterne that may indicate its availability as an adjuvant in the construction of chemical vaccines

IN VITRO ANTIOXIDANT AND MEMBRANE STABILITY ACTIVITIES OF EXTRACTS FROM LOMATOGONIUM CARINTHIACUM (WULF.) REICHENB. AND HYPECOUM ERECTUM L

In the present study the antioxidant and membrane stability activities of Lomatogonium. carinthiacum. (Wulf.) Reichenb. and. Hypecoum. erectum. L. extracts was determined using in vitro methods. It was found that the remedies shown expressed antioxidant and. membrane stability activities as a result of inactivation of the reactive oxygen forms and. inhibition of lipids peroxidation process