In december I studied the complex formation and its stability in Zn(II)-Sn(II)-Mo(VI)-citrate systems by cyclic voltammetry method, in a series of electrolytes with different concentrations of sodium citrate, sodium molybdate, zinc sulfate(IV), and tin sulfate (IV). All electrochemical measurements were carried out in a 95 cm3 cell, in a system with a rotating disc electrode to ensure a constant and controlled hydrodynamic conditions. The measurements were performed potentiodynamically in a three-electrode cell by means of potentiostat PARSTAT 2273.
Unfortunately I had to stop suddenly, the research because of the failure of potentiostat.

This month I have focused on reading scientific literature, mainly concerning basics of focused ion beams. Additionally, I was trying to do some experiments on the sample received from IOD last month, but I didn’t manage to successfully accomplish any of the trials.

Is familiar with the methodology of sample preparation for microstructural studies (specimens), and support for Leica optical microscope. Prepared zgłady blades - very responsible of engine airplane - the test is not marked on the strengthening and anti-corrosion layers. Studies have confirmed the presence of several layers, which could not be detected using a method of acoustic microscopy. Perhaps with such a thin (several micrometers) are undetectable to the acoustic microscope, despite attempts to use different types of heads and change measurement parameters.

Continuation of modelling the physical properties, especially density. The initial theoretical results are pure accordance with experimental data, only for liquid alloys displaying a negative deviation from Raolt’s law. The appeared difficulties come from bad definition the excess entropy or other factors omitted, however they are important in simulation the density.
Viscosity, the second physical properties, was investigated in terms of the well-know theoretical models and ab initio molecular dynamic simulation. Primary simulation the viscosity results are satisfactory. SCIGRESS package was used to work out the ab initio molecular dynamic simulation.
Definition of initial condition, choice of cell, positions of atoms and the more important potential for pure atoms and in alloys is main factor determining data being in good accordance with experimental data. For now, accessible package is insufficient for examination the large number of atoms in cell. For precise simulation is needed VASP package (Vienna Ab Initio Simulation Package), computes an approximate solution to the many-body Schr/o/dinger equation, within density functional theory (DFT), solving the Kohn-Sham equations or within the Hartree-Fock (HF) approximation, solving the Roothnaan equations.

PhD thesis - theoretical considerations

The second month of PhD studies at the Institute of Metallurgy and Materials Science passed so quickly… Christmas time will come and be gone in the blink of an eye...However, during that time I had been working on my PhD thesis a little bit and made literature review concerning surface zeta-potential topic.
Interactions between medical implants and their surrounding tissues are affected by the physicochemical surface properties of the implants. The electric charge of a material surface is considered to be one of the most important physical factors involved in the biological evolution of the tissue around an implant. This charge depends on several features, such as the chemical composition of the material, the inflammatory situation, the composition of the surrounding body fluid and the environmental pH value. The electric surface properties could be indicated by a biomaterial’s zeta-potential.
The zeta-potential is measured by electrophoresis or alternatively by streaming potential methods. The result of zeta-potential measurement is the potential of a material in an ionic solution at the boundary between the so-called Stern layer and the diffuse layer.
It is based on the charge displacement in the electric double layer caused by an external force shifting the liquid phase tangentially against the solid. Charge carriers temporarily bound in the double layer will be removed by the external flow with pressure, and the potential can be measured between two electrodes. Larger positive values of the zeta-potential at a fixed pH indicate positive charge of the surface which could attract anions or negatively charged proteins, while lower values reflect a negative charge of a material surface that tends to attract positively charged particles.
The aim of my nearest study will be to investigate the relationship between surface zeta-potential (surface charge property), protein adsorption and cell proliferation on PEM (polyelectrolyte multilayers) films, deposited on polyurethane base materials via “Layer by Layer” method.

1. Cai K., Frant M., Bossert J., Hildebrand G., Liefeith K., Jandt K. (2006) Surface functionalized titanium thin films: Zeta-potential, protein adsorption and cell proliferation, Colloids and Surfaces B: Biointerfaces 50:1-8.
2. Caster D., Ratner B. (2002) Biomedical surface science: foundations to frontiers, Surf. Sci. 500:28-60.
3. Lavenus S., Pilet P., Guichex J., Weiss P., Louarn G., Layolle P. (2011) Behaviour of mesenchymal stem cells, fibroblasts and osteoblasts on smooth surfaces, Acta Biomater. 7:1525-1534.

PhD thesis – experimental investigation

So far a series of trials designed to investigate the electrokinetic potential of the surface was done. The base material were coverslips. In accordance with the methodology at the outset coverslips were treated with NaOH solution at a concentration of 2M, 5M and 10M respectively. This treatment was carried out in order to produce a negative surface charge allowing binding of the first positively charged polyelectrolyte layer. Some treated samples were left to the quantitative and qualitative comparison of the effects of various NaOH concentration on base material activation. The proper series of nine samples was covered by twelve polyelectrolyte bilayers consist of poly-L-lysine and hyaluronan.

Seminars participation

-“Physical properties of liquid crystal mixtures of chiral and achiral compounds applied in LCDs” given by MSc. Eng. J. Czerwiec
-“Simulation of microstructure and texture development using Digital Material Representation and ‘Crystal Plasticity’ model” given by Dr Eng. W. Wajda
-“Unconventional methods of producing TiB2-TiN composites” given by MSc. Eng. P. Wyzga