635 research outputs found
New exact solutions for the evaporation flux density of a small droplet on a flat horizontal substrate with a contact angle in the range of 135-180 degrees
Previously [arXiv:2103.15582v3], an expression was proposed for the
evaporation flux density of a small liquid droplet having the shape of an
axisymmetric spherical segment deposited on a horizontal substrate. The
dependence of the flux density on the polar angle was established for arbitrary
contact angles. This formula has the form of an integral and is rather
complicated for use in modeling algorithms. An approximate expression was
obtained for the evaporation flux density at small contact angles. However, the
question of which simplified formulas should be appropriate to apply in other
ranges of contact angles, for example, in the case of obtuse angles remains
open. In this paper, we propose new exact solutions for the set of discrete
"hydrophobic" contact angles. As an example, very simple exact expressions are
obtained explicitly for the evaporation flux density for droplets with contact
angles 135 and 150 degrees that do not contain integral dependencies. They can
also be used as approximate solutions for a narrow range of contact angles
around the specified values.Comment: 7 pages, 2 figure
Computer Microscopy of Biological Fluid Dry Patterns for Medical Diagnostics
We elaborate hardware and software system that implements the principle of diagnosis based on the standard procedure of pattern preparation including digital recognition of image and its computer analysis based on specially developed algorithms by comparing with the expert descriptors and extensive database of dry pattern samples obtained from clinical treatments which include more than 1500 samples to high selective and accuracy recognition of pathologies, for recognition of wide range of pathologies, in particular, the endogenous intoxication.
Keywords: biological fluids, image analysis, medical diagnostics, endogenous intoxication
Experimental study of water evaporation of sessile droplets on a solid substrate with different thermal conductivities
The results of experimental studies of water evaporation of sessile droplet on solid substrates with different thermal conductivities are presented. In experiments during droplet evaporation the temperature of its surface was determined using the infrared thermography method. The obtained results showed that interfacial temperature was higher than the adiabatic evaporation temperature for all substrates. As thermal conductivity of the substrate decreased, the droplet temperature decreased and the evaporation lifetime increased significantly. As a result it was established that the thermal conductivity of the material has a significant effect on the evaporation of droplets
Effect of pulsed magnetic field pre-treatment of AISI 52100 steel on the coefficient of sliding friction and wear in pin-on-disk tests
Disc specimens manufactured from commercial bearing rollers (AISI 52100 steel, 62–63 HRC) in initial state and after pre-treatment by pulsed magnetic field (PMF) with a magnetic field strength of 1–7 MA/m were tested with sunflower oil using pin-on-disk apparatus. According to the obtained results the treatment causes a reduction in the coefficient of friction and wear. To explain the results, nano- and microhardness tests as well as optical and atomic force microscopy were used. Reasons of the effect of PMF on the friction and wear were discussed.Peer reviewe
The formation of Ti-O tetrahedra and band gap reduction in SiO2 via pulsed ion implantation
Titanium ions are implanted into amorphous SiO2 at two different fluences using pulsed ion implantation, and the resulting samples are annealed. Bulk sensitive soft X-ray absorption spectroscopy of the Ti L 2, 3 edge reveal strikingly different spectra for the two fluences. Spectral simulations using multiplet crystal field theory show clearly that for low fluence the Ti ions have a local octahedral coordination, while at higher fluence the formation of Ti4-O tetrahedra dominates. Using O K-edge X-ray absorption and emission, the effect of the Ti states on the valence and conduction bands of the host SiO2 is revealed. With the introduction of Ti tetrahedra, the band gap reduces from about 8 eV to just over 4 eV, due entirely to the Ti 3d conduction band states. These results demonstrate the possibility to obtain Ti-O tetrahedra in silica by Ti ion implantation and a suitable thermal treatment, clarify the mechanism of band gap reduction with Ti doping in SiO2, and demonstrate the sensitivity of L-edge X-ray absorption with a multiplet crystal field theory analysis to the Ti coordination of novel materials. © 2013 American Institute of Physics
Synthesis of porous silicon with silver nanoparticles by low-energy ion implantation
© 2015, Pleiades Publishing, Ltd. In this paper, a new technique is proposed for synthesis of porous silicon (PSi) layers with silver nanoparticles based on the method of low-energy high-dose metal ion implantation into Si. In order to demonstrate this technique, the implantation at room temperature of a polished Si wafer by Ag+ ions with the ion energy of 30 keV, ion dose of 1.5 × 1017 ion/cm2, and ion current density of 8 µA/cm2 is carried out. Using methods of high resolution scanning electron and atomic-force microscopy, electron probe microanalysis, and Raman scattering, it is shown that ion implantation results in the formation, on the surface of irradiated Si, of a thin amorphous layer of PSi with the average pore size of 150–180 nm, a pore depth of about 100 nm, and wall thickness between pores of about 30–60 nm. Moreover, the PSi structure contains Ag nanoparticles 5–15 nm in size. It is established that, during the ion implantation, the sputtering of the Si surface by Ag+ ions takes place, which was not observed previously. Based on the data obtained, it is concluded that, in contrast to chemical techniques, the proposed physical technique for PSi formation can be integrated into the modern advanced process of fabricating and improving electronic circuits based on industrial ion implantation
Notes about Passive Scalar in Large-Scale Velocity Field
We consider advection of a passive scalar theta(t,r) by an incompressible
large-scale turbulent flow. In the framework of the Kraichnan model the whole
PDF's (probability distribution functions) for the single-point statistics of
theta and for the passive scalar difference theta(r_1)-theta(r_2) (for
separations r_1-r_2 lying in the convective interval) are found.Comment: 19 pages, RevTe
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