National Repository of Grey Literature 10 records found  Search took 0.00 seconds. 
Electronic effects at the interface between biomolecules, cells and diamond
Krátká, Marie ; Rezek, Bohuslav (advisor) ; Cifra, Michal (referee) ; Skládal, Petr (referee)
Understanding and control of interactions between biological environment (cells, proteins, tissues, membranes, electrolytes, etc.) and solid-state surfaces is fundamental for biomedical applications such as bio-sensors, bio-electronics, tissue engineering and implant materials as well as for environmental monitoring, security and other fields. Diamond can provide unique combination of semiconducting, chemical, optical, biocompatible and other properties for this purpose. In this thesis we characterize electronic properties of protein-diamond interface by employing a solution-gated field-effect transistor (SGFET) based on hydrogen-terminated diamond, surface of which is exposed to biological media. We elucidate the role of adsorbed protein layer on the electronic response of the diamond transistor. We investigate effects of cells (using mainly osteoblast cells as model) on diamond SGFETs transfer characteristics and gate currents. We employ nanocrystalline diamond (NCD) thin films of different grain sizes (80 - 250 nm) to characterize and discuss influence of grain boundaries and sp2 phase on bio- electronic function of SGFETs. We investigate effects of gamma irradiation on function and stability of hydrogen-terminated diamond SGFETs interfaced with proteins and cells, showing feasibility of...
Monitoring the impact of exposure to electromagnetic fields in yeast colonies
Hájková, Renata ; Vorlíček, Jaroslav (advisor) ; Cifra, Michal (referee)
Identifikační záznam: HÁJKOVÁ, Renata. Sledování vlivu expozice elektromagnetickým polem na kolonii kvasinek [Monitoring the impact of exposure to electromagnetic fields in yeast colonies]. Praha, 2011, rok vydání. 74s., 2. příl. Diplomová práce (Mgr.). Univerzita Karlova v Praze, 1. Lékařská fakulta, Fakulta elektrotechnická, Katedra elektromagnetického pole, ČVUT v Praze. Vedoucí závěrečné práce Vorlíček, Jaroslav, Ing. Abstract: Current development of mobile telecommunication device increases interest of public to the question of influence of electromagnetic field to the living organisms. Results of this work contribute to better knowledge of interaction between electromagnetic field and cell structures. Beginning of the thesis is review of morphology and physiology of the yeast cell that was used in this work as a tested organism. Second chapter describe the basic facts about electromagnetic fiend and wireless energy transfer. Goal of the practical part of this master thesis is describe influence of electromagnetic field on population of yeast during their proliferation. We constructed special box connected with wireless energy generator that was source of exactly defined electromagnetic field. Cells of Saccharomyces cerevisiae were diluted in fluid medium YPD and the proliferation of the culture was...
Electromagnetic-based nano-resolution microscopies for biological research
Kučera, Ondřej ; Cifra, Michal
Research of cell biology is principally related to progress in imaging under diffraction limit of visible light and to the functional imaging. This paper brings short review of experimental techniques including Photonic force microscopy, Scanning microwave microscopy and other relevant techniques. The possibility of employing these techniques for elucidation of endogenous biological electromagnetic activity is discussed
Electric field generated by higher vibration modes of microtubule
Cifra, Michal ; Havelka, D. ; Kučera, Ondřej ; Pokorný, Jiří
Certain structures in a living cell may generate electric oscillations. Microtubules, which form a part of a cellular skeleton, belong to this class of structures and ful-fill all conditions for generation of electric oscillations in kHz÷GHz band. We present selected results from calculations of the oscillatory electric field generated by higher vibration modes of microtubules. We propose that the electric field of certain modes may play specific function in cellular organization
Calculation of the Electromagnetic Field Around Microtubule
Havelka, D. ; Cifra, Michal
Microtubules are important structures in cytoskeleton which organizes the cell. Single microtubule is composed of electrically polar structures, tubulin heterodimers, which have strong electric dipole moment. Vibrations are expected to be generated in microtubules, thus tubulin heterodimers as electric dipoles are oscillating. This gives rise to electromagnetic field, which is detected around the cells. We calculate here the electromagnetic field of microtubules if they are excited at 1 GHz. This paper includes the work done in bachelor thesis of the first author.
Measurement and Computer Simulation of Electromagnetic Oscillations of Living Cells
Cifra, Michal ; Pokorný, Jiří ; Vrba, J.
Frohlich postulated coherent polar oscillations as a fundamental biophysical property of biological systems. Recently, Pelling et al. (2004, 2005) detected mechanical vibrations of yeast cell membrane with atomic force microscope (AFM) and analyzed by Fourier analysis in the frequency range 0.5-2 kHz with amplitudes of the order of 1 nm. This article describes the measurement of electric activity of yeast cells in the acoustic frequency range and of mechanical vibrations of cell membrane. Spectrum analyzer and electrically and > electromagnetically screened box with point sensor and amplifiers fed by batteries were used for measurement of synchronized and non synchronized tubulin mutants of yeast cells. We show that the electric activity of synchronized cells in the M phase is greater that of non synchronized cells. That corresponds to the findings of Pohl et al. (1981). Obtained results of measurement of cell electric activity are in good agreement with AFM findings.
Ultra low frequency yeast cells electric activity
Cifra, Michal ; Pokorný, Jiří ; Jelínek, František ; Hašek, Jiří ; Šimša, Jan
This paper presents results from the measurement of the electrical activity cold sensitive beta-tubulin mutant tub2-401 of yeast cells in frequency region 0.4 - 1.6 kHz. 25 measurements of both synchronized and nonsynchronized cells show that the synchronized cells have higher electrical activity what corresponds to the findings of Pohl et al. Mechanical oscillations of electrically polar structures in cell may give rise to electric oscillations we measured.
Denní změny intenzity emise fotonu z lidských rukou
Cifra, Michal ; Van Wijk, E. ; Koch, H. ; Bosman, S. ; Van Wijk, R.
Spontaneous ultra-weak photon emission in the visible range was measured on palm and dorsal side of left and right hand by means of a low noise photomultiplier system. To study the dynamics of this photon emission in a 24h period photon emission was recorded in 2h intervals in 5 experiments. Mean photon emission over the 24h period differed both between subjects and hand locations. The fluctuations in photon emission in the course of 24h were more at dorsal sides than palm sides.
Lidská spontanní emise fotonu v průběhu 24 hodin
Cifra, Michal ; Van Wijk, E. ; Van Wijk, R.
Ultra-weak spontaneous photon emission in visible range from palms and hands of dark-accommodated subjects has been measured every two hours in 5 experiments in the course of 24 hours by means of low-noise photomultiplier. Dorsal sides of the hands show higher fluctuations of photon emission intensity than palmar sides. Cycles of fluctuations of the 1 day, 6-8 hours and 3-4 hours long period have been observed from Fourier analysis of the measured data.
Dynamika spontánní emise fotonu z lidského těla v průběhu 24 hodin
Cifra, Michal
Spontaneous ultra-weak photon emission in the visible range was measured on palm and dorsal side of left and right hand by means of a low noise photomultiplier system. To study the dynamics of this photon emission in a 24h period photon emission was recorded in 2h intervals in 5 experiments. Mean photon emission over the 24h period differed both between subjects and hand locations. The fluctuations in photon emission in the course of 24h were more at dorsal sides than palm sides.

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