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1

Single-Bond Force Measured by Means of Scanning Force Microscopy

100%

Lekka M., Gryboś J., Lekki J., Stachura Z., Styczeń J.

Acta Physica Polonica A

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2002

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vol. 102

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issue 3

355-364

EN

The aim of this investigation was to determine the adhesion force as a function of calcium dichloride concentration in water. The studies were performed with two surfaces carrying opposite charge in water solution: mica - as a negatively charged surface and glass covered with poly-L-lysine - as a positively charged surface, the latter due to the presence of amino groups. The surfaces were immersed in a CaCl_2 solution in the range of concentration varied from 0 to 100 mM. The scanning force microscopy was applied to determine the adhesion force by measurements of the pull-off force. Additionally, the values of the single bond force were estimated basing on the Poisson distribution of the number of binding sites.

2

Scanning Force Microscopy Studies of Implanted Silicon Crystals

100%

Lekki J., Lekka M., Romano H., Cleff B., Stachura Z.

Acta Physica Polonica A

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1996

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vol. 89

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issue 3

315-322

EN

Scanning force microscope has been applied to investigate wear tracks produced during friction coefficient measurements of hard steel ball against ⟨111⟩ silicon crystals implanted with Ar ions. Such treatment causes the stable and significant decrease in friction, despite the total removal of implanted species from the wear track during friction. Scanning force microscope measurements of wear tracks topography supported the former hypothesis assuming the formation of post-implantation dense microcracks structure and subsequent propagation of this structure into the bulk. Such process assures small size of wear particles and a low friction coefficient value. Additionally the microfriction force measurement method was applied to determine the friction coefficient of Si_{3}N_{4} cantilever and a wear track in Si crystal.

3

Single Proton Hit Facility at the IFJ PAN in Cracow

100%

Polak W., Lekki J., Veselov O., Stachura Z., Styczeń J.

Acta Physica Polonica A

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2006

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vol. 109

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issue 3

417-420

EN

This work presents the final development stage and optimization results of the single proton hit facility in Cracow. The setup parameters: proton beam energy 2 MeV, hit resolution 30μm, intensity ≈1000 proton/s, proton registration efficiency 100%, blanking efficiency 99.8%. On-line observation allows targeting cells inside a Petri dish mounted at a 3D precise moving stage. To target a particular cell a semiautomatic cell visualization and recognition system is used.

4

Determination of Changes in Sulphur Oxidation States in Prostate Cancer Cells

100%

Czapla J., Kwiatek W., Lekki J., Steininger R., Göttlicher J.

Acta Physica Polonica A

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2012

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vol. 121

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issue 2

497-501

EN

Prostate cancer cell lines along with selected organic and inorganic compounds used as references were studied with sulphur K-edge X-ray absorption near edge structure spectroscopy. The experiment was performed at the SUL-X beamline of the synchrotron radiation source ANKA, Karlsruhe (Germany). The sulphur was chosen for the studies because it is an essential biological element and out of many relevant factors, it is believed that it can take an important part in cancer transformations. The main goal was to determine which sulphur forms occur in prostate cancer cells and to compare these results with the ones obtained for non-cancerous cells. Therefore oxidation state of this element was analysed with S K-edge X-ray absorption near edge structure spectroscopy. The analysis of K-edge structure was done in order to investigate also the chemical structure of the elements neighbouring the central atom. The preliminary results from sulphur X-ray absorption near edge structure in prostate cancer cell line PC-3 and prostatic epithelial cell line PZ-HPV-7 (which was used as a control) show that there are various oxidation states of sulphur occurring in cells. The set of reference compounds with various sulphur oxidation states was used to establish the relation between the energy of the white line maximum and the oxidation state of sulphur. The equation of linear fit was used to compute the unknown oxidation state. In order to obtain a more detailed information the method of deconvolution of X-ray absorption near edge structure spectra was used. Experimental spectra were fitted with two Gaussian peaks and one arctangent step function. Fitting procedure was performed in Athena code and the deconvolution was used to assign the fraction of each sulphur form. The next step was to compare the results calculated for cancerous and non-cancerous cells. In this work, the first results of these studies are presented.

5

FTIR Microspectroscopy in Studies of DNA Damage Induced by Proton Microbeam in Single PC-3 Cells

100%

Lipiec E., Kowalska J., Lekki J., Wiecheć A., Kwiatek W.

Acta Physica Polonica A

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2012

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vol. 121

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issue 2

506-509

EN

In recent years, the Fourier transformed infrared spectroscopy is often applied in studies of biological materials on cellular level. Undoubted advantage of this method is high sensitivity. In presented research the FTIR microspectroscopy was used to analyse the DNA damage in single PC-3 cells (prostate cancer cell line derived from bone metastases) irradiated by counted number of protons. Focused proton microbeam 2 MeV from the Van de Graaff accelerator at the Institute of Nuclear Physics, Polish Academy of Sciences, was used as an irradiation source. Four groups of single cells were irradiated with 1000, 2000, 4000, and 8000 protons per cell, respectively. Following irradiation cells were fixed in 70% ethanol and then analyzed by IR microspectroscopy. Bond analysis of IR spectra served as a base for result analysis. This research has focused on the detection of changes in DNA backbone spectral range (950-1240 cm^{-1}), which could be related to damages such as single and double strand breaks, DNA-DNA, and DNA-protein cross links. Switches and differences in intensity of DNA backbone bands (980-1149 cm^{-1}, 1151-1350 cm^{-1} - symmetric and asymmetric PO^{2-} stretching vibrations, as well as in 1110 cm^{-1} - symmetric stretching of P-O-C band) were observed. Experimental spectra of irradiated and control cells were compared with simulated spectra generated by HyperChem software. The multivariate statistical methods of principal component analysis and hierarchical cluster analysis (Ward's method) were also performed and are discussed.

6

Applications of the Cracow X-Ray Microprobe in Tomography

100%

Bielecki J., Bożek S., Lekki J., Stachura Z., Kwiatek W.

Acta Physica Polonica A

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2009

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vol. 115

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issue 2

537-541

EN

A nuclear microprobe at the IFJ PAN in Cracow has found numerous applications in different fields of research, mostly in biophysics, medical sciences, geology, and material research. In order to extend the research possibilities, a new X-ray microprobe was constructed. This new microprobe consists of three experimental lines dedicated to: (i) X-ray irradiation of biological specimens, (ii) elemental analysis of samples by micro X-ray fluorescence or total reflection X-ray fluorescence methods and (iii) computer microtomography. In this paper the computer microtomography line was described. The line consists of an open type Hamamatsu L9191 X-ray tube with microfocusing to about 2 μm, a high resolution X-ray sensitive CCD camera, and a precise goniometer composed of six piezoelectric motors. Depending on the required X-ray energy, the Hamamatsu tube is used with Ti, Mo, Ag, or W targets. A small focus size and short focus-to-object distance enable to obtain images of samples with a magnification of more than 1000× and resolution of the order of 2 μm. The computer microtomography measurements are carried out using home developed codes combined with commercial software. Details of the microprobe construction and preliminary results of the computer microtomography experiments are presented.

7

Local Adhesive Surface Properties Studied by Force Microscopy

100%

Lekka M., Lekki J., Marszałek M., Stachura Z., Cleff B.

Acta Physica Polonica A

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1998

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vol. 93

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issue 2

421-424

EN

Scanning force microscopy was used in the contact mode to determine the adhesion force between a mica surface and a silicon nitride tip. The measurements were performed in an aqueous solution of sodium and calcium chlorides. The adhesion force according to the Derjaguin-Landau-Verwey- Overbeek theory depends on the competition between two kinds of forces: van der Waals and electrostatic "double layer". Two different curves of adhesion force versus salt concentration were obtained from the experiment with monovalent and divalent ions. The tip-surface adhesion force was determined from a statistical analysis of data obtained from the force vs. distance retracting curves.

8

Preliminary Investigations of Elemental Content, Microporosity, and Specific Surface Area of Porous Rocks Using PIXE and X-ray Microtomography Techniques

73%

Bielecki J., Bożek S., Dutkiewicz E., Hajduk R., Jarzyna J., Lekki J., Pieprzyca T., Stachura Z., Szklarz Z., Kwiatek W.

Acta Physica Polonica A

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2012

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vol. 121

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issue 2

474-479

EN

Determination of physical properties of porous geological materials is of great importance for oil industry. The knowledge of rocks properties is usually obtained from porosity studies such as pore size distribution, specific surface area determination, and hydrodynamic permeability calculations. This study describes determination of elemental composition and measurements of the particular physical properties of geological samples (porous sandstone rocks) by means of the nuclear and X-ray microprobes at the Institute of Nuclear Physics, Polish Academy of Sciences in Kraków, Poland. The special emphasis has been put on the computed microtomography method. Measurements have been carried out in close cooperation with Department of Geophysics, FGGEP AGH in Kraków, Poland. Chemical composition of the Rotliegend sandstone rock samples (few millimeters diameter), extracted from a borehole at 2679.6 m, 2741.4 m and 2742.4 m depth have been investigated using the 2.2 MeV proton beam (proton induced X-ray emission technique). Next, measurements of the porosity and the specific surface area of the pore space have been carried out using the X-ray microtomography technique. Basing on microtomographic data obtained with the high spatial resolution, simulations of the fluid dynamic in the void space of porous media have been carried out. Lattice Boltzmann method in the 3DQ19 geometrical model has been used in order to predict the hydraulic permeability of the media. In order to avoid viscosity-permeability dependence the multiple-relaxation-time model with half-way bounce back boundary conditions has been used. Computing power-consuming processing has been performed with the use of modern grid infrastructure.

Refine search results

Single-Bond Force Measured by Means of Scanning Force Microscopy

Scanning Force Microscopy Studies of Implanted Silicon Crystals

Single Proton Hit Facility at the IFJ PAN in Cracow

Determination of Changes in Sulphur Oxidation States in Prostate Cancer Cells

FTIR Microspectroscopy in Studies of DNA Damage Induced by Proton Microbeam in Single PC-3 Cells

Applications of the Cracow X-Ray Microprobe in Tomography

Local Adhesive Surface Properties Studied by Force Microscopy

Preliminary Investigations of Elemental Content, Microporosity, and Specific Surface Area of Porous Rocks Using PIXE and X-ray Microtomography Techniques