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1
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CPA Theory of Superconducting Alloys with Diagonal and Off-Diagonal Disorder

100%
Michalik M., Wysokiński K.
Acta Physica Polonica A
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2004
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vol. 106
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issue 5
653-658
EN
The general theory of disorder in superconducting alloys was discussed. We use standard Wannier function representation and allow for diagonal and off-diagonal disorder. We generalized the coherent potential approximation in the version able to deal with off-diagonal disorder in normal systems to treat superconducting state. As an illustration we calculate the quasiparticle density of states and gap function of a d-wave superconductor. We show inter alia that the rate at which superconductivity disappears depends on the kind of disorder and for off-diagonal disorder it depends on the details of its realization.
2
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Off-Diagonal Nonmagnetic Disorder in s- and d-Wave Superconductors

100%
Michalik M., Wysokiński K.
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EN
The previously developed approach to study off-diagonal disorder has been extended and applied to both s- and d-wave superconductors. The derived equations allow the self-consistent solution of the problem. For a special case of negative U centres embedded in non-superconducting host we have calculated their critical concentration for the appearance of superconductivity and found it equal to≈0.4. For x>x_{cr} the order parameter continuously increases to its maximal value at x=1.
3

Involvement of cytoskeleton in orientation of cell division in contact guided cells

81%
Krzysiek-Maczka G., Michalik M., Madeja Z., Korohoda W.
Folia Biologica
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2010
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vol. 58
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issue 1-2
21-27
EN
Single human skin fibroblasts and the skin keratinocyte cell line HaCaT show contact guidance and elongate along narrow (1-2 Fm) scratches in glass substratum. During cell division these cells orientate their mitotic spindles along the long axis of the cell. Immunofluorescence staining of actin, tubulin, chromatin, and the nuclear NuMA protein complex demonstrated that cell elongation along scratches is accompanied by a corresponding rearrangement in the cytoskeleton. The results and literature suggest the following steps in the interplay between outside-in and inside-out signalling in the regulation of cell division orientation by extracellular factors. The interaction of cell surface with an anisotropy in the local environment causes changes in F-actin organization, cell elongation and alignment of stress fibres along the cell axis. This is accompanied by a corresponding reorientation of microtubules. Microtubules mediate between cell shape changes dependent upon cell interaction with substratum or other cells, the cortical actin and the position of centrosomes. Centrosomes determine the position and orientation of the mitotic spindle. The astral and central microtubules of the mitotic spindle control the localization of contraction-relaxation in the cell cortex and the position of the constriction ring and cell division plane.
4

Contact-mediated acceleration of migration of melanoma B16 cells depends on extracellular calcium ions

81%
Madeja Z., Master A., Michalik M., Sroka J.
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EN
The escape of malignant cells from primary tumour and their active migration to the surrounding tissues are among the most important steps in the metastatic process. During migration, tumour cells interact with neighbouring neoplastic and normal cells and such interactions may affect their motile activity. We investigated the effect of extracellular calcium ions on migration of mouse melanoma B16 cells stimulated by homotypic cell-to-cell contacts. It was found that the decreasing of extracellular Ca2+ influx into B16 cells by lowering Ca2+ concentration in culture medium, or by the application of 0.5 mM La3+ (non-selective inorganic Ca2+ channels blocker), reduced the contact-mediated acceleration of migration of melanoma cells but only slightly affected the basal motile activity of non-stimulated single, separated cells moving without contacts with neighbouring ones in sparse culture. Since it was suggested that contact-mediated acceleration of migration of melanoma B16 cells may be controlled by mechanosensitive and/or voltage-gated ion channels, the presented data support the concept that these channels may affect cell migration by regulation of extracellular Ca2+ influx into stimulated cell.
5
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Thermal stability and pollutant adsorption efficiency of nanocomposites consisted of clay and polymeric quaternary ammonium salts

61%
Natkański P., Kuśtrowski P., Kochanowski A., Białas A., Piwowarska Z., Michalik M.
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2011
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vol. 66
47-59
EN
Polymer/layered silicate nanocomposites based on polymeric quaternary ammonium salts (ionenes) intercalated into the interlayer galleries of montmorillonite were synthesized. Zeta potential measurements were conducted to determine the amount of ionenes required to neutralize the negative charge of clay. The composition and structure of the obtained nanocomposites were examined by elemental analysis, ATR-FTIR and XRD. High dye sorption capacity was observed for the composite containing ionene 6,2.
6
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Controlling Structural and Functional Features of Photosynthetic Antenna

61%
Fiedor L., Fiedor J., Pilch M., Susz A., Tworzydło J., Michalik M.
Acta Physica Polonica A
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2012
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vol. 122
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issue 2
255-258
EN
In order to gain control over the assembly and functioning of photosynthetic antenna, we have developed methods to manipulate pigment composition of bacterial LH1 complexes via their reconstitution with modified bacteriochlorophylls or carotenoids, major photoactive cofactors of these antennae. In the present work we show how the reconstitution and pigment exchange approach is applied to control structural and functional parameters of LH1 and its subunits. The size of the subunits and the energy of the first excited singlet state can be controlled via the use of detergent while the thermodynamics of LH1 formation can be modified using carotenoids and/or a co-solvent. Carotenoids affect the efficiency of the intracomplex energy transfer, while the replacement of native bacteriochlorophyll a with its Ni-substituted analog allows one to control the excited state properties of LH1. These results show that LH1 is a very promising model system applicable for the design of bio-inspired device performing solar energy conversion.
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