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333 results on '"Kasperczyk J"'

21. Coupled bipolarons and optical phonons as a model for high-Tc superconductors

Author

Kasperczyk, J

Subjects
Solid-State Physics
Abstract

The coherence length of the new high-temperature superconductors reaches a small value which is comparable to the dimensions of the unit cell of the compound. This means that a pair consists of two holes occupying the same site or two adjacent sites. Such a situation is described by a model of the local-pairs (bipolarons). The origin of local-pairs may come not only from strong enough electron or hole-phonon interaction but also from other interactions. Independent of the specific nature of such local-pairs, they can undergo a Bose-like condensation to the superconducting state at a critical temperature which is usually much lower than the temperature of the pair formation. An interplay of ferroelectric and superconducting properties is considered within the model of hole-like local-pairs interacting with optical phonons. Therefore, researchers extend the usual local-pair Hamiltonian by including a direct interaction between the local-pairs and the optical phonons. These optical phonons are known to play an important role in the ferroelectric transition and they transform into an additional pseudo-acoustic branch at the ferroelectric critical temperature. (This is associated with nonzero electric polarization due to the existence of two separate lattices composed of negative and positive ions, respectively.)

Published
1991

23. Coupled bipolarons and optical phonons as a model for high-T(sub c) superconductors

Author

Kasperczyk, J

Subjects
Solid-State Physics
Abstract

The coherence length of the new high-temperature superconductors reaches very small value which is comparable to the dimensions of unit cell of these compounds. This means that a pair consists of two holes occupying the same site or two adjacent sites. Such a situation seems to be described by a model of the local-pairs (bipolarons). The origin of local-pairs may come not only from strong enough electron or hole-phonon interaction but also from other interactions. Independent of the specific nature of such local-pairs, they can undergo a Bose-like condensation to the superconducting state at a critical temperature which is usually much lower than the temperature of the pair formation. An interplay of ferroelectric and superconducting properties is considered within the model of hole-like local-pairs interacting with optical phonons. Therefore, researchers extend the usual local-pair Hamiltonian by including a direct interaction between the local-pairs and the optical phonons. These optical phonons are known to play an important role in the ferroelectric transition, if any, and they transform into an additional pseudo-acoustic branch at the ferroelectric critical temperature. (This is associated with nonzero electric polarization due to the existence of two separate lattices composed of negative and positive ions, respectively.)

Published
1990

27. Multifunctional PLGA/Parylene C Coating for Implant Materials : An Integral Approach for Biointerface Optimization

Author

Golda-Cepa, M., Chorylek, A., Chytrosz, P., Brzychczy-Wloch, M., Jaworska, J., Kasperczyk, J., Hakkarainen, M., Engvall, Klas, Kotarba, A., Golda-Cepa, M., Chorylek, A., Chytrosz, P., Brzychczy-Wloch, M., Jaworska, J., Kasperczyk, J., Hakkarainen, M., Engvall, Klas, and Kotarba, A.

Abstract

Functionalizing implant surfaces is critical for improving their performance. An integrated approach was employed to develop a multifunctional implant:coating based on oxygen plasma-modified parylene C and drug-loaded, biodegradable poly(DL-lactide-co-glycolide) (PLGA). The key functional attributes of the coating (i.e., anti-corrosion, biocompatible, anti-infection, and therapeutic) were thoroughly characterized at each fabrication step by spectroscopic, microscopic, and biologic methods and at different scales, ranging from molecular, through the nano- and microscales to the macroscopic scale. The chemistry of each layer was demonstrated separately, and their mutual affinity was shown to be indispensable for the development of versatile coatings, for implant applications., QC 20161005

Published
2016
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28. In vitro release of cytotoxic nucleoside analogs from lactide-caprolactone and lactide-glycolide copolymers

Author

Tomasz Kryczka, Bero, M., Kasperczyk, J., Dobrzynski, P., Marciniec, B., Popielarz-Brzezinska, M., and Grieb, P.

Subjects
Brain Neoplasms, Polyesters, Cladribine, Antineoplastic Agents, Fluorouracil, In Vitro Techniques, General Biochemistry, Genetics and Molecular Biology
Abstract

The aims of our study were to assess the release of cytotoxic nucleoside analogs 5-fluorouracil and 2-chloro-2'-deoxyadenosine from different lactide-glycolide or lactide-caprolactone biodegradable copolymers and the effects of sterilization on this release. The polymers were sterilized either with ethylene oxide at 37 degrees C, or with gamma radiation (15 kGy, 20 kGy, or 25 kGy). The kinetics of nucleoside release from the copolymers were measured over 50 days. Four copolymers exhibited relatively constant release of nucleosides in micromolar concentrations during the entire observation period. Sterilization with either ethylene oxide or gamma radiation only slightly influenced nucleoside release. Further development of these copolymers as an intracerebral nucleoside delivery system for local treatment of brain tumors is indicated.

Published
2002

30. Surface Effects and Critical Dimensions of Iron Nanoparticles

Author

Kozlowski, Gregory, primary, Chaudhary, V., additional, Turgut, Z., additional, Kosai, H., additional, Sheets, A., additional, Bixel, T., additional, Wheatley, A., additional, Abdulkin, P., additional, Knappett, B., additional, Jefferson, David, additional, Matusiewicz, M., additional, Kasperczyk, J., additional, and Makowska-Janusik, M., additional

Published
2015
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34. Laser induced microrelief superstructure of Ag/ITO seed-mediated nanocomposites

Author

90221861, Miedzinski, R., Ebothe, J., Kozlowski, G., Kasperczyk, J., Kityk, I. V., Fuks-Janczarek, I., Nouneh, K., Oyama, M., Matusiewicz, M., Reshakf, A. H., 90221861, Miedzinski, R., Ebothe, J., Kozlowski, G., Kasperczyk, J., Kityk, I. V., Fuks-Janczarek, I., Nouneh, K., Oyama, M., Matusiewicz, M., and Reshakf, A. H.

Published
2009

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