Lukáš Fojt

50 Hz magnetic field effect on the morphology of bacteria

Atomic force microscopy was used to distinguish changes in morphology of bacteria induced by 50 Hz 10 mT magnetic field exposure. It is known that alternating magnetic field exposure causes decrease of viability of different bacterial strains. Previously we found that the viability of rod-like bacteria exposed to magnetic field decreased twice more in comparison with the spherical ones. Motivated by this fact we carried out this study with bacterial cells of both shapes. We used Escherichia coli (rod-like) and Paracoccus denitrificans (spherical) bacteria. As a result we have not observed any change in bacterial morphology neither of rod-like nor of spherical bacteria after 1 h, 50 Hz and 10 mT magnetic field exposure.

Effects of 50 Hz Magnetic Fields on the Viability of Different Bacterial Strains

The effect of a 50 Hz magnetic field on the growth of different bacterial strains was studied. We used bacteria with different cell shapes. We compared rod-shaped bacteria (E. coli, L. adecarboxylata) and spherical bacteria (S. aureus, P. denitrificans, S. paucimobilis, R. erythropolis). The growth curves of control and magnetic fields exposed samples were measured. The cylindrical coil induced magnetic fields with inductions up to 10 mT. Duration of exposure varied up to 24 min. Exposure took place at laboratory temperature (24–26°C) and the air ventilator maintained the temperature of sample. We observed the decrease of optical densities in exposed samples. The magnetic field effect was bigger for rod-like bacteria. We concluded that magnetic field effects depend on the shape of exposed cells.

Adsorption and two-dimensional condensation of 5-methylcytosine

Purine and pyrimidine derivatives occurring in nucleic acids posses an extraordinary high ability of self-association at the electrode surface and can form there by a two-dimensional (2D) condensation a monomolecular compact film (self-assembled monolayer-SAM). The effects of methyl substituent on the 2D condensation were studied using the 5-methylcytosine molecule which is involved in gene silencing and has a great biological impact. At acid pHs, 5-methylcytosine forms at the mercury electrode a physisorbed self-assembled 2D layer at potentials close to the potential of electrocapillary maximum. From the temperature dependence of the electrode double layer capacitance, the standard Gibbs energy of adsorption (Delta G(m)=-12.7 kJ mol(-1)), lateral interaction coefficient of the Frumkin adsorption isotherm (a(c)=2.05) and area occupied by one molecule (A=1.31 nm(2)) in the 2D layer were determined. Measurements performed on a single-crystal Au(111) surface show that the 2D condensation can take place on other substrates as well.

Extremely-Low Frequency Magnetic Field Effects on Sulfate Reducing Bacteria Viability

50 Hz magnetic fields effects on Sulfate Reducing Bacteria (SRB) viability were studied by colony forming units (CFU) counting. We found a 15% decrease of CFU number after magnetic field exposure (B=7.1 mT, f=50 Hz, t=24 min) compared to the control samples. These results are in good agreement with our previous work on other bacterial strains. The magnetic field effects on SRB are relatively large for small magnetic fields. The data correlations have been subjected to a simple physical chemical analysis, yielding surprisingly large estimates for the characteristic magnetic reaction susceptibility, even when the entire bacterium is assumed to be the direct target of interaction of the magnetic ac fields for the exposures in the time range from 3–24 min.

Effects of ELF-EMF on Brain Proteins in Mice

Effect of electromagnetic low frequency fields was studied on mice. We analyzed level of protein in brain of mouse. The levels of c-Jun and c-Fos in brains were measured using Western-blot techniques. Female and male laboratory mice were exposed for 4 days to magnetic field (Bm = 2 mT, f = 50 Hz). The exposure took place in cylindrical coil at laboratory temperature. After the experiment they were sacrificed and the level of protein c-Jun and c-Fos in different parts of brain were estimated. The expression of c-Fos was not affected by magnetic field on the other hand the expression of c-Jun decreased after magnetic field exposure. The results did not depend on sex of mice.

Methodology for In Situ Microstructural Characterisation of AZ31 Magnesium Alloy Corrosion Degradation in Hanks' Solution

Due to their specific properties magnesium and magnesium alloys find huge application possibilities mainly in automotive, engineering, transport and space industry. Important properties of magnesium alloys for engineering applications are high specific strength and high internal dumping values, while biocompatibility, biotoxicity and biodegradability open them the possibility to be used for biomedical applications. Development of new biodegradable magnesium alloys, investigation of new production and processing technologies on their properties and evaluation of corrosion degradation in simulated body fluids solutions are the main topics of the last decades.The paper offers a method simulating in-vivo tests for description of the corrosion process of potential biomedical materials in time using atomic force microscopy (AFM). To prove the proposed methodology detailed analysis of the corrosion degradation of AZ31 cast magnesium alloy in flowing Hanks’ balanced salt solution (HBSS) was performed. Corrosion degradation process of the examined alloy was influenced by different microstructural features and their interfaces. Results of the created corrosion galvanic cells and the corrosion attack evolution on the interface of the present intermetallic phases and the matrix led to profile changes detected by AFM.

Indirect photometric detection of boron cluster anions electrophoretically separated in methanol

3,5-Dinitrobenzoate and picrate are light absorbing anions pertinent to indirect photometric detection of boron cluster anions in buffered methanolic background electrolytes (BGEs). Tris(hydroxymethyl)aminomethane and morpholine have been used as buffering bases, which eliminated baseline steps, and minimized the baseline noise. In methanolic BGEs, mobilities of boron cluster anions depend on both ionic constituents of the BGE buffer. This dependence can be explained by ion pair interaction of detected anions with BGE cations, which are not bonded into ion pairs with the BGE anions. The former ion pair interaction decreases sensitivity of the indirect photometric detection.

Fibrinogen and cellular adherability on differently treated titanium as implants

Adsorption of human plasma fibrinogen, osteoblasts, and fibroblasts on differently treated titanium samples as implants were examined in this study. Titanium samples were mechanically polished, chemically etched (with and without surface material loss), and grinded. The main goal of this study is to find the best surface treatment of titanium for its possible use as implants. Atomic force microscopy was used to evaluate the adsorption of human plasma fibrinogen onto the titanium samples. Cell counting was used to determine the adherability of osteoblasts and fibroblasts on the titanium samples. Our preliminary results show that the etched titanium surface with surface material loss is the best surface treatment used in our experiments.