Biomedical subjects

Z Adamczyk

Publications and source records attributed to Z Adamczyk.

15 recordsLinked to original sources

PubMed1999

Colloid Particle Adsorption in the Slot Impinging Jet Cell.

A detailed description of flow distribution in the slot impinging jet cell (SIJ) is presented. Numerical solutions of the governing Navier-Stokes equation showed that for Re < 30 the flow resembles closely the one occurring near a cylinder placed in a uniform flow. It was also shown that for tangential distances x/d < 0.25 the flow configuration in the vicinity of the solid can be approximated by the plane-parallel stagnation flow with the perpendicular velocity component independent of this distance. This flow field was used for deriving the mass transfer equation, which was then numerically solved to obtain the initial flux (adsorption rate) for various transport conditions. These theoretical predictions were verified experimentally using polystyrene latex particles of the size 1 and 1.48 µm. A good agreement between predicted and measured initial flux values was found for a broad range of Reynolds number and ionic strength of the particle suspension. This confirmed that the SIJ cell surface was uniformly accessible for particles at distances x/d < 0.5. At larger distances a systematic deviation from uniform deposition rates was observed, becoming important for higher coverages and Re. This effect was attributed to the hydrodynamic scattering of adsorbing particles on particles already attached to the surface. This phenomenon was quantitatively accounted for by the Brownian dynamics type simulations. Copyright 1999 Academic Press.

Journal Article↗

PubMed1997

NOTE

The adsorption kinetics of negatively charged polystyrene latex at mica surface precovered with smaller sized (submicrometer) latex particles was investigated experimentally. The direct microscope observation method combined with the impinging jet technique was used in this study. Experimental results were presented concerning the initial flux and adsorption kinetics of larger particles at surfaces partially covered with smaller sized latex particles. The experimental results were interpreted in terms of the Monte Carlo simulations performed using the random sequential adsorption (RSA) model. Limiting analytical solutions for predicting the initial flux and adsorption kinetics were also formulated. It was found that the experimental results were in good agreement with theoretical predictions (derived for hard particle interaction potential). This confirmed the hypothesis that small colloid particles present in low concentration at surfaces considerably diminish adsorption rates of larger particles. Copyright 1997 Academic Press. Copyright 1997Academic Press

Journal Article↗

PubMed1997

Calculations of Double-Layer Electrostatic Interactions for the Sphere/Plane Geometry

A numerical scheme for solving the nonlinear Poisson-Boltzmann equation for the sphere/sphere and plane/sphere geometries has been developed. The method is based on an alternating direction overrelaxation procedure using the Newton-Raphson iteration to solve the nonlinear equation stemming from finite-difference discretization. The novelty of the algorithm consists in using the grid transforming functions that allow a more uniform distribution of mesh points in the vicinity of the particle. The method was used to perform extensive calculations for opposite surface potentials of the interface and the particle immersed in a symmetric electrolyte solution. The electric potential distribution (within and outside the sphere) was calculated, as well as the force and energy of interaction (from the integral of the force over separation distance), for the constant potential, the constant charge, and the mixed cases. The energy profiles calculated for various kappaa were compared with the analytical approximations derived using the Hogg-Healy-Fuerstenau method and the linear superposition approach (LSA). These calculations enabled us to conclude that the LSA can be used as a good estimate of interaction energy for a broad range of kappaa values at distances greater than kappa-1, i.e., for problems pertinent to colloid particle adsorption.

Journal Article↗

PubMed1997

Influence of Polydispersity on Random Sequential Adsorption of Spherical Particles

Random sequential adsorption (RSA) of polydisperse mixtures of hard and interacting spherical particles was analyzed. Theoretical results were derived by performing numerical MC simulations both for Gaussian and for continuous distributions of particle sizes characterized by standard deviations below 20%. Adsorption kinetics of these mixtures was determined for a broad range of times showing that for tau < 5 the influence of polydispersity was rather minor for both Gauss and continuous particle size distributions. More significant deviations were predicted for the asymptotic adsorption regime close to jamming. In the case of continuous distributions this limiting kinetics could be described by the power law dependence thetainfinity - theta approximately tau-1/3 in accordance with the predictions of G. Tarjus and J. Talbot (1991, J. Phys. Math Gen. 24, L913). The jamming concentration thetainfinity for hard (noninteracting) particles was found to increase proportionally to sigma;. It was also shown that the polydispersity of particle mixtures can exert an effect on the structure of the adsorption layer (characterized in terms of the pair correlation function). The broadening of this function was confirmed experimentally by using colloid suspensions of spherical particles (polystyrene latex) characterized by sigma; = 6-10%.

Journal Article↗

PubMed1986

[Preliminary results of studies on the incidence, causes and effects of occupational accidents in the Bełchatów Industrial Region. III. Health effects of occupational accidents].

Health effects of accidents at work at the Bełchatów Industrial District have been investigated. Most injuries due to accidents have been bruises, wounds and bone fractures of upper and lower limbs. Much less frequent, as compared to other industrial plants, are injuries of head, chest and abdomen. The causes of those injuries have been discussed. In addition, the activities of occupational health services have been analysed.

Accidents, Occupational↗

PubMed1986

[Preliminary results of studies of the incidence, causes and effects of occupational accidents in the Bełchatow Industrial District. I. Direct causes of occupational accidents].

The work has been aimed at an analysis of accidents at work occurring throughout 1981-1982 at the Bełchatów Industrial District. The most common causes of accidents at work have been direct factors resulting mainly from workers' inadvertence or recklessness, improper performance of occupational tasks, lack of appropriate tools, and settlement of private affairs at work. The incidence of accidents at work might be reduced by compliance with safety-and-hygiene-of-work rules, better supervision, work organization and efficient working tools.

Accidents, Occupational↗

PubMed1986

[Preliminary results of studies on the incidence, causes and effects of accidents at work in the Bełchatów Industrial District. II. Indirect causes of accidents at work].

The work is a continuation of studies of accidents at work at the Belchatów Industrial District. Analysed have been indirect factors causing accidents at work. Those factors were found to cause accidents much more often than the direct ones. They are particularly significant for young workers. The season, month, day of month, consecutive working hour and climate did not significantly affect the frequency of accidents.

Accidents, Occupational↗

PubMed1983