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Changes of the Electrode Surface Roughness Induced by High-Voltage Electric Pulses as Revealed by AFM

100%
Rodaitė-Riševičienė R., Saulis G., Snitka V.
Acta Physica Polonica A
|
2009
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vol. 115
|
issue 6
1095-1097
EN
The changes of the surface topography of stainless-steel and aluminium electrodes occurring due to the action of electric pulses which are utilized for cell electroporation, have been studied by using atomic force microscopy. The surfaces of the polished stainless-steel electrodes were smooth - the average roughness was 13-17 nm and the total roughness 140-180 nm. The total roughness of the aluminium electrodes was about 320 nm. After the treatment of the chambers filled with 154 mM NaCl solution by a series of short (20-40 μs), high-voltage (4 kV) pulses with the total dissolution charge of 0.20-0.26 A s/cm^{2}, the roughness of the surface of the electrodes has increased, depending on the total amount of the electric charge that has passed through the unit area of the electrode. Up to a two- and threefold increase of the surface roughness of the stainless-steel and aluminium anodes respectively was observed due to the dissolution of the anode material. Therefore, the use of high-voltage electric pulses leads to the increase of the inhomogeneity of the electric field at the electrode, which facilitates the occurrence of the electric breakdown of the liquid samples and causes non-equal treatment of each cell.
2
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Small Angle X-Rays Scattering Studies of Biomolecules

100%
Funari S.
Acta Physica Polonica A
|
2002
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vol. 101
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issue 5
647-658
EN
The building units of biological systems, the biomolecules, cannot easily be organized or even classified into defined categories. They can be as simple as water or complex as tintin, a muscle protein extremely large with several thousand atoms. To understand their function, one must know their characteristics, where they occur and what they do. One approach to reach such an ambitious task is to determine their structure, as single molecules or assembled into aggregates. Small angle X-ray scattering is the most important method for this purpose. We present studies carried out on several systems, and aiming at different questions about them. We start with lipids, the main components of the cell membranes. These membranes form the cell boundaries, the moiety required for the so-called membrane proteins, but also influence significantly several aspects of biological activity. More complex systems like a muscle fibre is also presented, showing that changes in the structure are related to the movement mechanism. It becomes easy to conclude that knowing the structures and the changes occurring in them is an important way to understand the function of biomolecules and therefore their role in the life cycle.
3
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Measurement of Small Variations in Optical Properties of Turbid Inclusions with Respect to Surrounding Turbid Medium

88%
Bliznakova I., Vankov O., Dreischuh T., Avramov L., Stoyanov D.
Acta Physica Polonica A
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2009
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vol. 116
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issue 4
681-683
EN
Special optical system for non-invasive determination of small variations in the optical properties of homogeneous turbid inclusions embedded into large turbid medium is proposed and developed experimentally. Results for different choice of the optical parameters of both media are presented. The minimum detectable changes in the inclusion optical properties are estimated to be less than 5% with respect to the surrounding medium. It is shown that the output signals depend not only on the relative magnitude but also on the sign of the difference in optical properties of both media. The results could be used for developing techniques and algorithms for distinguishing of different kinds of abnormal formations.
4
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Challenges in Biology and Medicine with Synchrotron Infrared Light

63%
Dumas P., Miller L., Tobin M.
Acta Physica Polonica A
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2009
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vol. 115
|
issue 2
446-454
EN
The brightness (or brilliance) of synchrotron radiation was exploited in infrared microspectrosocopy. Among application of this synchrotron-based microanalytical technique, biological and biomedical investigations, at the diffraction-limited spot size, are exhibit of an increasing interest among almost all the existing infrared beamline worldwide. This paper is presenting the main properties of such a source, coupled with an infrared microscope. Several important applications in biomedical field are reported: cancer cells studies and drug effects, human substantia nigra in Parkinson's disease, β-amyloids deposits in Alzheimer's disease.
5
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A virtual instrumentation based protocol for the automated implementation of the inner field compensation method

51%
Mereuta L., Luchian T.
Open Physics
|
2006
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vol. 4
|
issue 3
405-416
EN
One influential parameter which mediates interactions between many types of molecules and biological membranes stems from the lumped contributions of the transmembrane potential, dipole potential and the difference in the surface potentials on both sides of a membrane. With relevance to cell physiology, such electrical features of a biomembrane are prone to undergoing changes as a result of interactions with the aqueous surrounding. Among the most useful tools devoted to exploring changes of electrical parameters of a lipid membrane induced by certain extracellular ions, lipid composition, and embedded membrane peptides and proteins, are spectroscopic imaging and the inner field compensation (IFC) method. In this work we layout the principles of a fully computerized version of the IFC method, which makes it more readily available to users. As a direct application, we deployed this improved version of the IFC method to time-resolve changes induced by alamethicin monomers upon membrane dipole potential, following their aggregation within an artificial lipid membrane. Intriguingly, even prior crossing the membrane core, the membrane-bound alamethicin monomers are shown to significantly increase the dipole potential of the monolayer they reside in. Such data further emphasize the yet less-explored interplay between membrane-based protein and peptides, and the membrane dipole potential.
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