West Bohemian University

Plzeň, Czech Republic

West Bohemian University

Plzeň, Czech Republic

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Lombardi G.,University of Rome La Sapienza | Sestak J.,West Bohemian University | Sestak J.,ASCR Institute of Physics Prague
Journal of Thermal Analysis and Calorimetry | Year: 2010

Dr. Robert Cameron Mackenzie was an eminent scientist who gave a major contribution to the progress of science in the fields of thermal analysis and clay minerals. He was a leading figure in the East-West cooperation at times when these relations were politically very difficult. The authors give an outline of his achievements and some personal recollections of his activity. © 2010 Akadémiai Kiadó, Budapest, Hungary.


Queiroz C.A.,New University of Lisbon | Sestak J.,West Bohemian University | Sestak J.,ASCR Institute of Physics Prague
Physics and Chemistry of Glasses: European Journal of Glass Science and Technology Part B | Year: 2010

Disordered matter still presents stringent conceptual difficulties. The often confused concepts of amorphous and glassy states (and corresponding material substances) were re-examined and previous attempts to trace a distinction are revised and thoroughly discussed. We examine several rheological and thermodynamical aspects of glasses in the glass transformation region as well as the dynamics of associated relaxation processes.


Sestak J.,West Bohemian University | Sestak J.,ASCR Institute of Physics Prague
Thermochimica Acta | Year: 2013

Description of the work and achievements of a new editor of Thermochimica Acta, Professor N. Koga, is specified as well as his recognition by the highest awards of the Czech Republic. In consequence the recent result of the Czech activities in thermal analysis and calorimetry is portrayed including recent conferences and book published. © 2013 Elsevier B.V. All rights reserved.


Kozmidis-Petrovic A.,University of Novi Sad | Sestak J.,West Bohemian University | Sestak J.,ASCR Institute of Physics Prague
Journal of Thermal Analysis and Calorimetry | Year: 2012

The revision of the meaning of the famous Hrubý glass-forming coefficient (as well as of other analogous coefficients by, e.g., Weinberg and Lu-Liu) reveals some generalized correlations between glass-forming ability (GFA) and glass stability. The relative change of the Hrubý parameter is supreme in almost all cases. The Hrubý parameter is more sensitive in relation to the change of both the super-cooled region and the reduced glass-transition temperature. The only exception is the restricted sensitivity respecting the reciprocal reduced glass-transition temperature in some cases of the bulk metallic glasses. The correlation of the Hrubý coefficient with GFA is agreeable for oxide glasses and thus can be commonly employed as a reliable and precise glass-forming criterion. Associated problems are the experimental determination of relevant temperatures, most pertinent that for glass transition which is dependent to preparative condition of glass formation. © Akadémiai Kiadó, Budapest, Hungary 2011.


Sestak J.,West Bohemian University | Kozmidis-Petrovic A.,University of Novi Sad | Zivkovic Z.,University of Belgrade
Journal of Mining and Metallurgy, Section B: Metallurgy | Year: 2011

The meaning of experimentally determined characteristic temperatures is analysed in terms of Hruby glass forming criterion. Despite various analysed modifications it reveals that the sensitivity of original criterion is unsurpassable. The applicability of Sestak-Berggren empirical equation for the description of crystallisation kinetics is comparable with the classical modelling based on Johnson-Mehl-Avrami equation. Their employment is certainly dependent to the purpose of evaluation showing their substitution ability and limits.


Foller B.,West Bohemian University | Holub M.,West Bohemian University | Holub M.,Brno University of Technology | Sestak J.,West Bohemian University
Journal of Thermal Analysis and Calorimetry | Year: 2014

Three types of composites prepared by special pultrusion technology are tested for acoustic suitability as designed for industrial production of vibrating rods. Thermosetting pultrusion as a novel technique is introduced in more details. Isophtalic polyester matrix (Ashland S 599) reinforced by glass roving (OCV) discharged optimum results providing best listening tests in accordance with the dynamic mechanical analysis measurements of relative bend factor (Young's modulus) and glass transformation temperature (T g) as well as with the transverse vibrational frequencies and the sound attenuation in impact tests. © 2014 Akadémiai Kiadó, Budapest, Hungary.


Flickyngerova S.,Slovak University of Technology in Bratislava | Netrvalova M.,West Bohemian University | Sutta P.,West Bohemian University | Novotny I.,Slovak University of Technology in Bratislava | And 3 more authors.
Thin Solid Films | Year: 2011

The effects of power and pressure on radiofrequency (RF) diode sputtering in oblique-angle (80°) deposition arrangement are presented. Oblique-angle sputtering of ZnO:Ga (GZO) thin films resulted in a tilted columnar crystalline structure and inclination of the c-axis by an angle of approximately 9° with respect to the substrate. This improved their structural, electrical and optical properties in comparison with films deposited perpendicularly to the substrate. GZO films sputtered by an RF power of 600 W at room temperature of the substrate in Ar pressure 1.3 Pa showed strong crystalline (002) texture, lowest electrical resistivity 3.4 × 10 - 3 Ωcm, highest electron mobility 10 cm 2 V - 1 s - 1, high electron concentration 1.8 × 10 20 cm - 3 and good optical transparency up to 88%. The small inclination angle of the film structure is caused by the high kinetic energy of sputtered species and additional energetic particle bombardment causes random surface diffusion, which is suppressing the shadow effect produced by oblique-angle sputtering. © 2011 Elsevier B.V. All rights reserved.


Sestak J.,West Bohemian University
Journal of Thermal Analysis and Calorimetry | Year: 2012

Extent of citation is analysed and the best citied papers mentioned accentuating Journal of Thermal analysis and Thermochimica Acta. The relevant scope of papers is uncovered and some viewpoints are shown. The sphere of kinetics appears the most cited subject matter. © 2011 Akadémiai Kiadó, Budapest, Hungary.


Sestak J.,West Bohemian University | Foller B.,West Bohemian University
Journal of Thermal Analysis and Calorimetry | Year: 2012

The state-of-art of polyaluminosialates is reviewed in terms of inorganic hmersi showing the composition, degree of netting, function of modifying atoms and the role of non-bridging oxygen as well as hydroxyl groups (biocompatibility). The polymeric condensation is compared with the vitrification of glasses upon cooling. The replacement of Si by P is discussed as well as the analogous precipitation process of amorphous hydrous silica (opal). Progress of geopolymers and biopolymers usefulness is shown within the framework of generalized world of macromolecules screening hundred contemporary citations. Pultrusion technology is presented, capable to produce composite geopolymers reinforced by basalt fibers staying suitable for mechanical applications. © Akadémiai Kiadó, Budapest, Hungary 2011.


Sestak J.,West Bohemian University
Journal of Thermal Analysis and Calorimetry | Year: 2012

Modeling tradition is reviewed within its historical maturity from Plato do Penrose. Metaphors in nonisothermal kinetics achieved a wide application mostly employing models derived by means of undemanding isothermal descriptions. Geometrical basis of such modeling is revised and discussed in terms of symmetrical and asymmetrical (pentagonal) schemes. The properties of interface (reaction separating line) are found decisive in all cases of heterogeneous kinetics. Application of fractal geometry is accredited, and associated formal kinetic models based on nonintegral power exponents are acknowledged. Typical erroneous beliefs are dealt with showing common kinetic misinterpretation of measured data and associated mathematical manipulability of kinetic equations. The correction of a measured DTA peak is mentioned assuming the effects of heat inertia and temperature gradients. © 2011 Akadémiai Kiadó, Budapest, Hungary.

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