Fyzikální ústav

Nejnovější přírůstky:
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.

Úplný záznam
2018-03-09
13:19
Laser-driven ablation through fast electrons in PALS experiment
Gus'kov, S. Yu. ; Chodukowski, T. ; Demchenko, N. ; Kalinowska, Z. ; Kasperczuk, A. ; Krouský, Eduard ; Pfeifer, Miroslav ; Pisarczyk, P. ; Pisarczyk, T. ; Renner, Oldřich ; Skála, Jiří ; Šmíd, Michal ; Ullschmied, Jiří
Energy transfer to shock wave in Al and Cu targets irradiated by a laser pulse with intensity of I~1-50 PW/cm2 and duration of 250 ps was investigated at Prague Asterix Laser System (PALS). The iodine laser provided energy in the range of 100-600 J at the first and third harmonic frequencies. The focal spot radius of laser beam on the target was varied from 160 to 40 µm. The dominant contribution of fast electron energy transfer into the ablation process was found when using the first harmonic radiation, the focal spot radius of 40-100 µm, and the energy of 300-600 J. The fast electron heating results in the growth of ablation pressure from 60 Mbar at the intensity of 10 PW/cm2 to 180 Mbar at the intensity of 50 PW/cm2 and in the growth of the efficiency of the energy conversion into the shock wave from 2 to 7 % under the conditions of 2D ablation.

Úplný záznam
2018-03-07
15:28
Study of photocatalytic activity of Zn.sub.x./sub.Cd.sub.1-x./sub.S quantum dots in dependence on their composition using methylene blue
Praus, P. ; Svoboda, L. ; Hospodková, Alice ; Mamulová Kutláková, K.
ZnCdS quantum dots (QDs) with the different composition were prepared by precipitation of zinc and cadmium acetates with sodium sulphide in the presence of cetyltrimethylammonium bromide (CTAB) used for stabilization of their aqueous colloid dispersions. Transition energies of these quantum dots were determined from the UV-VIS spectra of QDs colloid dispersions and consequently used for calculation of the QDs sizes according to the Schrodinger equation. The ZnCdS QDs size was found to be significantly influenced by their composition: the QDs size decreased with the increasing Zn content. The photocatalytic activity of the ZnCdS QDs was studied using the methylene blue decomposition under UV irradiation. Different photocatalytic activity depending on the composition x was observed and explained. The maximal photocatalytic activity was achieved for x = 0.6 when the energy of the irradiation photons was still sufficient to generate electron-hole pairs in majority of the QDs and at the same time the photocatalytic surface area was maximal.\n

Úplný záznam
2018-03-07
15:28
Model of static recrystallization in the coarse-grained B2 iron aluminide
Schindler, I. ; Šumšal, V. ; Kopeček, Jaromír ; Kawulok, P. ; Jozwik, P. ; Rusz, S. ; Kawulok, R. ; Opěla, P.
Microstructure of the laboratory castings made from Fe-40at.%Al-Zr-B alloy was homogenized by the multipass hot rolling in protective capsules and subsequent lannealing. Based on the isothermal hot compression tests and EBSD analysis, the sufficiently accurate model describing the static recrystalization kinetics of the such prepared coarse-grained B2 iron aluminide after strain 0.2 was developed. The independent variables in this model are temperature of deformation as well as annealing time equal to the deformation temperature. Unexpected effect of the previous strain value on the static softening was observed. Static recrystallization begins relatively easy in the studied alloy in the whole range of testing temperatures (900-1100 °C), but a very long-term annealing is quite necessary for the complete course of recrystallization.\n

Úplný záznam
2018-03-07
15:28
Modeling of nanofibers interaction with the environment
Klicmanová, I. ; Sveshnikov, Alexey
Nanomaterials change our life. Every day they find applications in new branches of technology. At the same time, some branches of technology, like civil engineering, are rather conservative and do not accept new approaches lightly. Nanotextiles exhibit a number of qualities that make them a promising material for civil engineering applications. They can potentially play a role of filters, protective layers, armature and others. Properties of the nanotextiles can be significantly influenced by parameters of technological process. Pure experimental search of the optimal technological parameters to achieve the desired properties of the final material can be very tedious. Thus, a theoretical dependence of the properties of the nanotextile on parameters of the technological process must be established. Two independent tasks must be solved for this: the dependence of nanotextile structure on technological parameters, and determination of physical, chemical or biological properties of a nanotextile of a given structure. In this paper we discuss steps necessary for the solution of the second task.

Úplný záznam
2018-03-07
15:28
Initial study of structure of nanofiber textiles and the creation of its model
Havrlík, M. ; Sveshnikov, Alexey
In this research, the structure of the fabrics was analyzed using an electron scanning microscope Tescan Maia 3. Two sets of the experiments have been carried out. In the first experiment the surface structure of the samples was studied. Photos created by SEM were analyzed using program Atlas and image editor GIMP. In this set of the experiments the initial parameters for the creation of a digital 2D model of a single layer have been determined (fiber size distribution, pore size and curvature of the fibers). In the second set of the experiments cross sections of nanofiber textiles were made in order to study the inner structure of the fabric. This information allows evaluation of the total number of 2D layers in the model and, thus, is very important for future creation of a 3D model of the fabric.

Úplný záznam
2018-03-07
15:28
Controlled structuring of self-assembled polystyrene microsphere arrays by two different plasma systems
Domonkos, Mária ; Ižák, Tibor ; Stolcova, L. ; Proška, J. ; Kromka, Alexander
In this study we present a successful manipulation of microspheres by reactive ion etching (RIE). A self-assembled monolayer close-packed array of monodisperse polystyrene microspheres (PM) with diameter of 471 nm was used as the primary template. The PM templates were processed in two different RIE systems: (i) capacitively coupled radiofrequency plasma (CCP) and (ii) dual plasma system which combines CCP and pulsed linear-antenna microwave plasma (PLAMWP). The influence of process conditions on the PM geometry was systematically studied by scanning electron microscopy (SEM). It was found out that choosing optimal parameters results in a tunable diameter of PM with various shapes (from spheres to pyramid-like structures) while keeping their periodic hexagonal ordering.

Úplný záznam
2018-03-07
15:28
Influence of dispersed particles on utility properties od polyvinyl alcohol-based nanotextiles: macromechanical properties
Rácová, Z. ; Nežerka, V. ; Ryparová, Pavla ; Kromka, Alexander ; Tesárek, Pavel
The paper deals with the influence of different dispersed particles on utility properties of polyvinyl-alcohol (PVA) based nanofiber textiles. The purpose of the dispersed particles was to produce textiles of antibacterial character, and these were added into water-polymer solution, which was used for electrospinning in two various ways: in form of copper and silver ions, or in form of diamond nanoparticles. In order to assess the strength of textiles, macromechanical testing of modified PVA-based nanofiber textiles was carried out on samples with variable weight per area in range between 0.5 and 5 g/m(2). The obtained results were compared with the results of measurements on plain reference samples. The study revealed that the addition of silver ions causes the strength and stiffness reduction, the addition of copper ions has an opposite effect, while the diamond nanoparticles did not have any significant influence on the mechanical properties.\n

Úplný záznam