249 research outputs found
Hard-wall Potential Function for Transport Properties of Alkali Metals Vapor
This study demonstrates that the transport properties of alkali metals are
determined principally by the repulsive wall of the pair interaction potential
function. The (hard-wall) Lennard-Jones(15-6) effective pair potential function
is used to calculate transport collision integrals. Accordingly, reduced
collision integrals of K, Rb, and Cs metal vapors are obtained from
Chapman-Enskog solution of the Boltzman equation. The law of corresponding
states based on the experimental-transport reduced collision integral is used
to verify the validity of a LJ(15-6) hybrid potential in describing the
transport properties. LJ(8.5-4) potential function and a simple thermodynamic
argument with the input PVT data of liquid metals provide the required
molecular potential parameters. Values of the predicted viscosity of monatomic
alkali metals vapor are in agreement with typical experimental data with the
average absolute deviation 2.97% for K in the range 700-1500 K, 1.69% for Rb,
and 1.75% for Cs in the range 700-2000 K. In the same way, the values of
predicted thermal conductivity are in agreement with experiment within 2.78%,
3.25%, and 3.63% for K, Rb, and Cs, respectively. The LJ(15-6) hybrid potential
with a hard-wall repulsion character conclusively predicts best transport
properties of the three alkali metals vapor.Comment: 21 pages, 5 figures, 41 reference
Numerical simulation of thermal properties in two-dimensional Yukawa systems
New results obtained for thermal conduction in 2D Yukawa systems. The results
of numerical study of heat transfer processes for quasi equilibrium systems
with parameters close to conditions in laboratory experiments with dusty plasma
are presented. The Green-Kubo relations are used to calculate thermal
conductivity and diffusivity coefficients. For the first time the influence of
dissipation (friction) on the heat transfer in non-ideal systems is studied.
New approximation is suggested for thermal diffusivity. The comparison with the
existing experimental and numerical results is shown.Comment: 18 pages, 9 figure
Enhancements of nucleate boiling under microgravity conditions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76852/1/AIAA-2000-853-986.pd
Master singular behavior for the Sugden factor of the one-component fluids near their gas-liquid critical point
We present the master (i.e. unique) behavior of the squared capillary length
- so called the Sudgen factor-, as a function of the temperature-like field
along the critical isochore, asymptotically close to the gas-liquid critical
point of twenty (one component) fluids. This master behavior is obtained using
the scale dilatation of the relevant physical fields of the one-component
fluids. The scale dilatation introduces the fluid-dependent scale factors in a
manner analog with the linear relations between physical fields and scaling
fields needed by the renormalization theory applied to the Ising-like
universality class. The master behavior for the Sudgen factor satisfies
hyperscaling and can be asymptotically fitted by the leading terms of the
theoretical crossover functions for the correlation length and the
susceptibility in the homogeneous domain recently obtained from massive
renormalization in field theory. In the absence of corresponding estimation of
the theoretical crossover functions for the interfacial tension, we define the
range of the temperature-like field where the master leading power law can be
practically used to predict the singular behavior of the Sudgen factor in
conformity with the theoretical description provided by the massive
renormalization scheme within the extended asymptotic domain of the
one-component fluid "subclass"
Probing polydopamine adhesion to protein and polymer films: microscopic and spectroscopic evaluation
Polydopamine has been found to be a biocompatible polymer capable of supporting cell growth and attachment, and to have antibacterial and antifouling properties. Together with its ease of manufacture and application, it ought to make an ideal biomaterial and function well as a coating for implants. In this paper, atomic force microscopy was used to measure the adhesive forces between polymer-, protein- or polydopamine-coated surfaces and a silicon nitride or polydopamine-functionalised probes. Surfaces were further characterised by contact angle goniometry, and solutions by circular dichroism. Polydopamine was further characterised with infrared spectroscopy and Raman spectroscopy. It was found that polydopamine functionalisation of the atomic force microscope probe significantly reduced adhesion to all tested surfaces. For example, adhesion to mica fell from 0.27 ± 0.7 nN nm-1 to 0.05 ± 0.01 nN nm-1. The results suggest that polydopamine coatings are suitable to be used for a variety of biomedical applications
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