Search results for " tension"
showing 10 items of 270 documents
A study of the refractive index and surface tension synergy of the binary water/ethanol: influence of concentration
2005
Pure alcohols or alcohols mixed with water are the most widely used solvents in a great variety of industrial applications, including the formulation of pharmaceutical and cosmetic products. As a result of water/alcohol molecular associations, variations result in the physico-chemical characteristics of the system, such as density, viscosity, refractive index and surface tension. The present study investigates the refractive index and the surface tension of ethanol and water mixtures at a temperature of 25°C, for different molar fractions. The data obtained allow us to study the corresponding refractive index and the surface tension synergies; in this sense, an absolute maximum refractive i…
Micelles, Rods, Liposomes, and Other Supramolecular Surfactant Aggregates: Computational Approaches
2017
Surfactants are an interesting class of compounds characterized by the segregation of polar and apolar domains in the same molecule. This peculiarity makes possible a whole series of microscopic and macroscopic effects. Among their features, their ability to segregate particles (fluids or entire domains) and to reduce the surface/interfacial tension is the utmost important. The interest in the chemistry of surfactants never weakened; instead, waves of increasing interest have occurred every time a new field of application of these molecules has been discovered. All these special characteristics depend largely on the ability of surfactants to self-assemble and constitute supramolecular struc…
Respiratory Gas Transport in Heart
1973
The purpose of this paper is to describe an attempt to obtain a better understanding of the dynamics of the oxygen supply of the myocardium under physiological and pathophysiological conditions by examining the oxygen diffusion in the heart muscle tissue during systole and diastole. In comparison to other organs the oxygen supply of the myocardium is characterized by a number of specific features. The most important one is that the gas exchange in the myocardium is a nonsteady-state diffusion process.
Depletion of carbon nanotube depositions and tube realignment in the spreading of sessile drops
2015
Abstract We studied spreading of drops of water and dilute alcohol on multiwall carbon nanotube (MWNT) depositions. These deposits consisted of individual arc-discharge synthesized MWNTs and irregular amorphous carbon nanoparticles on hydrophilically rendered silicon substrates. The mobile circular contact line of a spreading drop created an annular shape on the deposit, where some of the MWNTs and the amorphous nanoparticles in particular were largely depleted. The effect was strongly dependent on the hydrophilicity of the substrate. Most of the MWNTs were not only left within the annuli, but were also apparently reoriented by their interaction with the passing contact line. Our results im…
Prognostic Potential Of The Pretherapeutic Tumor Oxygenation Status
2009
Hypoxia, a characteristic feature of locally advanced solid tumors, has emerged as a key factor of the tumor pathophysiome, since it can promote tumor progression and resistance to therapy. Independent of established prognostic parameters, such as clinical tumor stage, histology, histological grade and nodal status, hypoxia has been identified as an adverse prognostic factor for patient outcome. Studies of pretreatment tumor hypoxia involving direct assessment (polarographic oxygen tension measurements) have suggested a poor prognosis for patients with hypoxic tumors. These investigations indicate a worse disease-free survival for patients with hypoxic cancers of the uterine cervix or soft …
The Role of Oxygen Tension Distribution on the Radiation Response of Human Breast Carcinoma
1994
The response of tumors to radiation is heterogeneous even in animal tumor systems where tumors all originate from the same cell culture, are implanted in genetically similar age-matched animals in a constant anatomic locationl. Hence great heterogeneity of response exists even in situations where intrinsic genetic or epigenetic factors are minimally variable. Several metabolic factors are known to influence the probability of tumor control after radiation. These metabolic factors are also known to vary widely between tumors in humans2,3 and even in animal tumor models. Heterogeneous variables include tumor oxygen tension distribution, glutathione content, glucose delivery and utilization ra…
Effects of Neuromuscular Electrical Stimulation Training on Endurance Performance
2016
Various electrical stimulation modalities are used as adjuvants to conventional training and rehabilitation programs to increase bodily function or to reduce symptoms, such as pain. One of these modalities, neuromuscular electrical stimulation (NMES), commonly refers to the transcutaneous application of electrical currents to a target muscle group with the objective to depolarize motor neurons and consequently elicit skeletal muscle contractions of substantial intensity (usually ranging from 10 to 60% of the maximal voluntary contraction). Because NMES can generate considerable muscle tension, it is frequently used as a strength training technique for healthy adults and athletes, but also a…
Human Mammary Carcinomas in Nude Rats — A New Approach for Investigating Oxygen Transport and Substrate Utilization in Tumor Tissues
1985
An understanding of tumor pathophysiology with respect to blood flow, oxygenation status, pH distribution and utilization of the relevant substrates which, all together, critically influence growth kinetics and the efficiency of nonsurgical therapeutic modalities in vivo requires information derived directly from human malignant tissues. At present, only inadequate knowledge of the relevant physiological factors in tumor tissues of patients are accessible. The little data available to date were obtained from clinical observations rather than from systematic studies, i.e., data were collected from various tumor types with differing staging and grading. For this reason generally valid stateme…
Interfaces in polymer blends
2000
We investigate the structure and thermodynamics of interfaces in dense polymer blends using Monte Carlo (MC) simulations and self-consistent field (SCF) calculations. For structurally symmetric blends we find quantitative agreement between the MC simulations and the SCF calculations for excess quantities of the interface (e.g., interfacial tension or enrichment of copolymers at the interface). However, a quantitative comparison between profiles across the interface in the MC simulations and the SCF calculations has to take due account of capillary waves. While the profiles in the SCF calculations correspond to intrinsic profiles of a perfectly flat interface the local interfacial position f…
Semiflexible polymers under good solvent conditions interacting with repulsive walls.
2016
Solutions of semiflexible polymers confined by repulsive planar walls are studied by density functional theory and Molecular Dynamics simulations, to clarify the competition between the chain alignment favored by the wall and the depletion caused by the monomer-wall repulsion. A coarse-grained bead-spring model with bond bending potential is studied, varying both the contour length and the persistence length of the polymers, as well as the monomer concentration in the solution (good solvent conditions are assumed throughout, and solvent molecules are not included explicitly). The profiles of monomer density and pressure tensor components near the wall are studied, and the surface tension of…