Fyzikální ústav

Nejnovější přírůstky:
2018-11-26
14:31
Electronic transfer between nanostructures. Negative differential resistance in conductive polymers.
Král, Karel ; Menšík, Miroslav
The effect of negative differential resistance can be observed experimentally in some material systems based on polymers. These observation are explained usually to be due to the presence of certain carrier traps which can capture the carriers of the electric current. In the present theoretical work we are going to show that besides this carrier trapping origin of the negative differential resistance there can also be an intrinsic mechanism present, causing such an effect. Namely, instead of the traps, the electron-phonon interaction can cooperate with the tunneling of the charge carriers between their localized states and can provide the effect the negative differential resistance. This electron-phonon interaction is included in a non-perturbative way. The theory will be briefly summarized and explained.

Úplný záznam
2018-11-26
14:31
Histology and micro-CT study of diamond-coated metal bone implants
Potocký, Štěpán ; Ižák, Tibor ; Dragounová, Kateřina ; Kromka, Alexander ; Rezek, Bohuslav ; Mandys, V. ; Bartoš, M. ; Bačáková, Lucie ; Sedmera, David
A conformal coating of a thin diamond layer on three-dimensional metal bone implants was shown directly on stainless steel and TiAl6V4 cortical screw implant using ultrasonic and composite polymer pretreatment method. The best conformation coverage was achieved in the case of the WO3 interlayer for both stainless steel and TiAl6V4 screws. The process of osteointegration of the screw implants into rabbit femurs is evidenced by the formation of a bone edge via desmogenous ossification around the screws in less than six months after implantation. A detailed evaluation of the tissue reaction around the implanted screws shows good biocompatibility of diamond-coated metal bone implants.

Úplný záznam
2018-11-26
14:31
Characterization of hydrogenated silicon thin films and diode structures with integrated germanium nanoparticles
Stuchlík, Jiří ; Fajgar, Radek ; Kupčík, Jaroslav ; Remeš, Zdeněk ; Stuchlíková, The-Ha
Substrates with ZnO (or ITO) conductive layers were covered by thin film of a-Si:H deposited by PECVD technique. Under a turbo-molecular vacuum (10-4 Pa) the reactive laser ablation (RLA) was used to cover this a-Si:H thin film by germanium NPs. The RLA was performed using focused excimer ArF laser beam (193 nm, 100 mJ/pulse) under SiH4 background atmosphere (0.5 Pa). As a target the elemental germanium was used. Reaction between ablated Ge and silane led to formation of Ge NPs covered by thin SiGe layer. Then the deposited NPs were covered and stabilized by a-Si:H layer by PECVD. Those two deposition processes was alternated and applied a few times. The Si:H thin films with integrated Ge NPs were characterized by microscopic, spectroscopic and diffraction techniques. I-V characteristics of final diode structures without and under illumination were measured as well as their electroluminescence behaviour.

Úplný záznam
2018-11-26
14:31
The hydrogen plasma doping of ZnO thin films and nanoparticles
Remeš, Zdeněk ; Neykova, Neda ; Potocký, Štěpán ; Chang, Yu-Ying ; Hsu, H.S.
The optical absorptance and photoluminescence studies has been applied on the hydrogen and oxygen plasma treated, nominally undoped ZnO thin films and aligned nanocolumns grown on the nucleated glass substrate by the hydrothermal process in an oil bath containing a flask with ZnO nutrient solution. The localized defect states at 2.3 eV below the optical absorption edge were detected by photothermal deflection spectroscopy (PDS) in a broad spectral range from near UV to near IR. The optical absorptance spectroscopy shows that hydrogen doping increases free electron concentration changing ZnO to be electrically conductive (hydrogen doping).\n

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2018-11-15
12:43
XXIII Czech-Polish seminar: Structural and ferroelectric phase transitions
Hlinka, Jiří ; Pokorný, Jan ; Bubnov, Alexej
This is the Book of Abstracts for the XXIII Czech-Polish Seminar (CPSEM-2018 conference) held in Kouty on May 21 - 25, 2018. The special objective of the conference is expressed in the conference subtitle: Structural and Ferroelectric Phase Transitions. The continuous worldwide interest to this conference series is proving that it has a respected position within the series of International/European conferences covering all interdisciplinary field of the research related to structural and ferroelectric phase transitions. At the CPSEM-2018 conference more than 110 participants from 14 countries all over the world presented 16 invited lectures and selected 36 oral contributions. About 60 posters were presented during two poster sessions.

Úplný záznam
2018-11-15
12:39
Alternative approach to the hysteresis of transport current in Bi-based tapes
Nálevka, Petr ; Jirsa, Miloš ; Koblischka, M. R. ; Pan, V. M. ; Dew-Hughes, D. ; Huang, S. L.
The induced critical currents and the reversible magnetic moment were studied in Bi-based samples prepared by different technologies, in a wide range of temperatures and external magnetic fields.

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2018-11-15
12:39
Chracterisation of the magnetisation hysteresis in RE-123 superconductors by exponentially decaying and power-law functions
Jirsa, Miloš ; Koblischka, M. R. ; Higuchi, T. ; Murakami, M.
The fully developed fishtail shape of the magnetization hysteresis loops in untwined RE-123 bulk materials is well characterized by the logarithmic pinning potential U(j) in frames of the thermally actived pinning process.

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2018-07-30
11:02
Rychlé a citlivé stanovení metforminu v lidské moči a séru pomocí kapilární elektroforézy s bezkontaktní vodivostní detekcí
Tůma, P. ; Fauknerová-Matějčková, J. ; Jurka, Vlastimil ; Samcová, E.
Kapilární elektroforéza s detekcí bezkontaktní vodivosti byla použita k přímé derminaci antidiabetického léku metforminu v lidském moči a séru. Merformin se oddělí v 2M kyselině octové jako elektrolyt bakground. Monitorování hladin metforminu v moči se provádí na krátké separační cestě za vysoké elektrické intenzity. Za těchto podmínek je doba migrace metforminu 35 s a detekční limit je 0,3 uM.\n

Úplný záznam
2018-04-18
16:23
Metodika použití nízkoteplotního plazmatu ve veterinární léčbě
Dejneka, Alexandr ; Kubinová, Šárka ; Moravec, J. ; Bezděk, D.
Cílem metodiky je aplikace nízkoteplotního plazmatu ve veterinární léčbě. Nízkoteplotní plazma (NTP) má nespecifické antimikrobiální účinky a lze jej bezpečně aplikovat na živé tkáně, aniž by došlo k jejich poškození. Metodika předkládá řešení dermatologických problémů s potenciální bakteriální, plísňovou či kvasinkovou kontaminací. Metodu lze použít také k antimikrobiální dekontaminaci a podpoře hojení chronických a nehojících se ran.

Úplný záznam
2018-04-06
16:29
Nanomechanical testing of an a-C:N nanolayer prepared by ion beam assisted deposition on Ti.sub.6./sub.Al.sub.4./sub.V alloy
Vlčák, P. ; Šepitka, J. ; Horaždovský, T. ; Jirka, Ivan ; Gregora, Ivan ; Němec, M.
We applied ion beam assisted deposition for preparing a-C:N nanolayers on Ti6Al4V alloy. A Hysitron TI 950 TriboIndenter (TM) nanomechanical test instrument was used to assess the depth profiles of the mechanical properties on modified titanium substrates. Two methods were employed : a) quasistatic partial unload, and b) dynamic Continuous Measurement of X (CMX). The average nanoindentation hardness increased from HIT similar to 5GPa for a reference sample to HIT similar to 8.6 GPa for a sample coated by an a-C nanolayer, and to HIT similar to 11.5 GPa for a sample coated by an a-C:N nanolayer. The average storage modulus of the sample coated by a-C:N increased from E' similar to 130 GPa (reference sample) to E' similar to 155 GPa. The storage modulus of the sample coated by the a-C nanolayer was less than the storage modulus of the titanium substrate.

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