Investigation into the mechanism of bacterial adhesion to hydrogel-coated surfaces

As a model for hydrogel-coated biomaterials, self-assembled monolayers of polyoxyethylene (POE) derivatives on sheets of polymeric biomaterials were prepared. The POE derivatives consisted of hydrophilic chains with different lengths and a long-chain alkyl group that served as an anchor function. The coatings obtained were analyzed with XPS and contact angle measurements showing hydrophilic chains of different lengths extending away from the surface. Bacterial adhesion was measured with a clinically relevant Klebsiella pneumoniae type strain and measurements reproduced 12 times. Bacterial adhesion decreased markedly with increasing hydrophilic chain length. Based upon these findings a new model for bacterial adhesion to hydrogel-coated surfaces is suggested: steric repulsion effects that increase with increasing chain length of grafted hydrophilic chains play an important role in bacterial adhesion to hydrogel-coated surfaces. © 1999 Kluwer Academic Publishers     

Physical mechanism of the wetting of solid surfaces

This article examines physical principles in the theory of wetting. Wetting angles are calculated by using isotherms of the disjoining pressure of wetting liquid films on solid substrates.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 5, pp. 795–802, November, 1987.     

The temperature field in a body bounded by conical surfaces due to an instantaneous annular heat source

The authors investigate the influence of the internal cavity and apex angle of a cone on the temperature field due to an instantaneous annular source.     

Reconstruction of the temperature field in a solid from a limited number of measurements

We have obtained extrapolation formulas for calculating the temperatures, temperature gradients, and heat fluxes in a solid heated by a varying thermal flux from the results of temperature measurements at two points. The applicability limits and errors of the proposed formulas have been investigated.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 3, pp. 553–558, September, 1969.     

The nonsteady temperature field of a solid under the nonsymmetric and time-variable conditions of heat transfer

A method is proposed for the approximate solution of nonsteady heat-conduction problems under the nonsymmetric and time-variable boundary conditions of the third kind, applicable to bodies of arbitrary shape.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 1, pp. 118–126, July, 1969.     

The longitudinal electrical conductivity of metal-matrix composites at cryogenic temperature in the presence of a longitudinal magnetic field

We solve the Boltzmann equation in the relaxation time approximation with parallel E and B fields parallel to the continuous fibres reinforcing a metal matrix. It is shown that this solution is identical to that described by us elsewhere, except for the addition of the cyclotron frequency. The addition of the cyclotron frequency term shows that the electrons follow helical paths as they drift down the composite. The boundary considered is either the external or the internal surface of a cylinder representing the fibre. To apply this solution to metal-matrix composite materials we assumed that the cylindrical fibres are non-conducting cylinders in a matrix of pure crystalline metal. The electron mean free path is never greater than half the fibre separation distance. In a companion paper we discuss the application of this solution to metal-matrix composites.     

Interaction of a moist capillary-porous solid with a hot gas flow

An experimental investigation of the temperature distribution in the boundary layer of air above a capillary-porous solid from which a liquid is evaporating is described. An analysis of the experimental results confirms Lykov's hypothesis of the presence of a bulk evaporation source in the boundary layer of air above a capillary-porous solid. This source increases the rate of heat and mass transfer from the solid to the air flow.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 17, No. 3, pp. 463–469, September, 1969.     

Thermophysical properties of moist disperse materials in a magnetic field

Results are shown of an experimental study concerning the thermal conductivity and the thermal diffusivity of grade KSK-2 silica gel and of Glukhovets kaolin with various levels of moisture content in a constant nonuniform magnetic field varying from 0 to 6000 Oe.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 24, No. 5, pp. 876–880, May, 1973.     

The longitudinal electrical conductivity of metal matrix composites at cryogenic temperature in the presence of a longitudinal magnetic field

In this paper we use the results of Part I to derive two integral expressions for the electrical conductivity of metal matrix composite materials when a magnetic field, B, is added to a small electric field also parallel to fibres. One expression applies to strong magnetic fields meaningR ₀/a < 1, whereR ₀ =m ^* v _F/eB when the Fermi velocity is perpendicular to the magnetic field. WhenB , the integral expression reduces to the well known conductivity value = ₀(1 -V _f), where ₀ is the bulk matrix conductivity andV _f is the fibre volume fraction. For weak magnetic fields,R ₀/a > 1, then the electrical conductivity is expressed by the sum of two integrals. When B 0, the electrical conductivity reduces to the integral expression obtained in our earlier results when there is only a longitudinal electric field. In this paper we correct an incorrect derivation of the composite conductivity in the absence of a magnetic field published earlier [J. Mater. Sci.21 (1986) 2409].     

Determining the steady-state temperature field in a cracked plate with heat transfer from the lateral surfaces

The heat conduction problem is considered in the case of a plate with a thermally insulated straight crack and with a given prior temperature field in the solid plate. The heat transfer from the plate to the ambient medium is assumed to follow Newton's law.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 23, No. 1, pp. 126–131, July, 1972.     

The temperature field of an infinite solid containing a cylindrical channel with a thermally thin surface coating

The Laplace method of integral transformation is used to find an analytical solution of the problem of unsteady-state heat conduction for an infinite isotropic solid containing a cylindrical channel with a thermally thin surface coating filled with a high-temperature gas.     

Modeling of heat transfer in an isotropic velocity field in the presence of a transverse temperature gradient

Known second-order models are verified in a test problem of an isotropic velocity field with a constant temperature gradient.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 54, No. 1, pp. 14–20, January, 1988.     

Fundamental study on adhesion of ice to solid surface: Discussion on coupling of nano-scale field with macro-scale field

In a previous study, it was reported that the removal process (behavior) of ice from a cooling solid surface depended on the characteristic of the solid surface, and that the ice adhesion force to the cooling surface was mainly governed by the surface energy of the surface. In the present study, using the method of surface analysis, the ice removal process and the ice adhesion force clarified in a macro-scale field were also discussed in a nano-scale field to couple these scale fields. Simultaneously, another surface analysis of the solid surface was carried out to identify the distributions of hydrophilic and hydrophobic groups on a solid surface. Attempts to couple the nano-scale field with the macro-scale field revealed that the results for both scale fields were in approximate qualitative agreement.     

Optical emission from laser-induced breakdown plasma of solid and liquid samples in the presence of a magnetic field

The optical properties of laser-induced plasma generated firm solid (Al alloy) and liquid (Mn, Cr, Mg, or Ti solutions) samples expanded across an external, steady magnetic field have been studied by atomic-emission spectroscopy. Various line emissions obtained from the constituents of the Al alloy and of the aqueous solution show an enhancement in intensity in the presence of an approximately 5-kG magnetic field. The enhancement of the signal was nearly a factor of 2 for the minor constituents of the solid samples and a factor of 1.5 for the elements in liquid phase. Temporal evolution of the emission from the solid sample showed maximum enhancement in emission intensity at 3-10-micros time delay after plasma formation in the laser energy range 10-50 mJ. However, for the liquid sample the maximum signal was for a gate delay of 3-25 micros the energy range 50-200 mJ. This enhancement in the emission intensity was found to be due to an increase in effective density of the plasma as a result of magnetic confinement when the plasma cooled after expansion. This enhanced emission was due to an increase in the rate of radiative recombination in the plasma.     

Use of the schlieren method to investigate temperature fields in a solid

The use of the Schlieren method to measure the temperature field and temperature gradients in a solid is considered. The results obtained are compared with a theoretical calculation of the temperature field in a finite cylinder for boundary conditions of the second and third kind.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 20, No. 3, pp. 510–514, March, 1971.     

Characterization of neutrophil adhesion to different titanium surfaces

Although titanium (Ti) is known to elicit a foreign body response when implanted into humans, Ti implant healing resembles normal wound healing in terms of inflammatory cell recruitment and inflammation persistence. Rough implant surfaces may present better conditions for protein adsorption and for the adhesion of platelets and inflammatory cells such as neutrophils. Implanted biomedical devices initially interact with coagulating blood; however, direct contact between the oxide layer of the implant and neutrophils has not been completely described. The aim of the present study is to compare the behaviours of neutrophils in direct contact with different Ti surfaces. Isolated human neutrophils were placed into contact with Ti discs, which had been rendered as ‘smooth’ or ‘rough’, following different surface treatments. Scanning electron microscopy and flow cytometry were used to measure cell adhesion to the surfaces and exposure of membrane proteins such as CD62L and CD11b. Topographic roughness was demonstrated as higher for SLA treated surfaces, measured by atomic force microscopy and elemental analysis was performed by energy dispersive X-ray, showing a similar composition for both surfaces. The adhesion of neutrophils to the ‘rough’ Ti surface was initially stronger than adhesion to the ‘smooth’ surface. The cell morphology and adhesion marker results revealed clear signs of neutrophil activation by either surface, with different neutrophil morphological characteristics being observed between the two surface types. Understanding the cellular mechanisms regulating cell–implant interactions should help researchers to improve the surface topography of biomedical implant devices.     

The temperature field of a plate in a solidified gas

We examine the problem of finding the temperature field of a plate heated by a constant flow of heat from one end and releasing heat to the solidified gas from the remaining sides through a gas interlayer.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 16, No. 5, pp. 842–848, May, 1969.