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Advantageous mechanochemical synthesis of copper(Ⅰ)selenide semiconductor,characterization,and properties

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Frontiers of Chemical Science and Engineering 2022年第3期16卷 433-442页

作者： Katarína Gáborová Marcela Achimovičová Michal Hegedüs vladim.r Girman Mária Kaňuchová Erika Dutková Institute of Geotechnics Slovak Academy of SciencesKošice04001Slovakia Institute of Metallurgy Faculty of MaterialsMetallurgy and RecyclingTechnical UniversityKošice04201Slovakia Synthon s.r.o.Blansko67801Czech Republic Faculty of Science Pavol JozefŠafárik UniversityKošice04154Slovakia Institute of Earth resources Faculty of MiningEcologyProcess Control and GeotechnologiesTechnical UniversityKošice04200Slovakia

Copper(I)selenide-nanocrystalline semiconductor was synthesized via one-step mechanochemical synthesis after 5 min milling in a planetary ball *** kinetics of synthesis was followed by X-ray powder diffraction analysis and specific surface area measurements of milled 2Cu/Se *** X-ray diffraction confirmed the orthorhombic crystal structure of Cu_(2)Se with the crystallite size∼25 *** surface chemical structure was studied by X-ray photoelectron spectroscopy,whereby the binding energy of the Cu 2p and Se 3d signals corresponded to Cu^(+)and Se^(2−)oxidation *** electron microscopy revealed agglomerated nanocrystals and confirmed their orthorhombic structure,as *** optical properties were studied utilizing ultraviolet-visible spectroscopy and photoluminescence *** direct bandgap energy 3.7 eV indicated a blue-shift phenomenon due to the quantum size *** type of Cu_(2)Se synthesis can be easily adapted to production dimensions using an industrial vibratory *** advantages of mechanochemical synthesis represent the potential for inexpensive,environmentally-friendly,and waste-free manufacturing of Cu_(2)Se.

关键词： Cu_(2)Se berzelianite nanocrystalline semiconductor mechanochemical synthesis planetary ball mill

Applicability of high-temperature cooling systems in different European countries from the view of the condensation risk

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Building Simulation 2021年第5期14卷 1453-1466页

作者： vladim.r Zmrhal Martin Bartak Czech Technical University in Prague Faculty of Mechanical EngineeringDepartment of Environmental Engineering Technicka 416000 Prague 6Czech Republic

Due to the different approaches in determining the ventilation airflow rate per person for workspaces,where high-temperature air conditioning systems are used for air conditioning,problems with the condensation of water vapour on the cold surfaces of the system can *** article analyses the risk of condensation in various European cities using the available climatic *** with cooling ceilings and cooling beams with a ventilation device operating in parallel are taken into *** ventilation airflow rates per person were *** the example of a room equipped with high-temperature cooling,an energy simulation calculation is performed,which includes a ventilation and air-conditioning system with the possibility of capacity *** is clear from the results that the condensation of water vapour can be prevented by technical measures at the cost of reducing the cooling capacity,which can affect the achievement of the thermal comfort of those *** the end,suitable solutions are discussed,which should already be adopted at the time the device is designed so that the risk of condensation is not a major obstacle in the operation of these energy-efficient *** irreplaceable role in the operation of high-temperature cooling systems is played by a measurement and control system with a suitable algorithm to prevent condensation.

关键词： ventilation air-conditioning cooled ceilings chilled beams low energy cooling risk of condensation

Determination of the sensible heat effectiveness and pressure loss of a rotary regenerative heat exchanger using CFD

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Building Simulation 2023年第6期16卷 869-887页

作者： vladim.r Zmrhal Petr Zelenský Jindřich Boháč Martin Barták Miroslav Kučera roman Vavřička Faculty of Mechanical Engineering Department of Environmental EngineeringCzech Technical University in PragueTechnická416000Prague 6Czech Republic

The paper presents a new method to determine the sensible effectiveness and pressure loss of rotary regenerative heat exchangers using computational fluid dynamics(CFD).It is based on CFD simulations of a single thermal wheel microchannel with a small cross-sectional area and thin walls,with cyclic inlet and outlet boundary *** unique measurement set-ups were designed and built for the experimental measurement of the heat exchanger *** different types of thermal wheels were manufactured,measured,and simulated in AnSYS *** wheels achieve an effectiveness greater than 73%under certain(air flow)conditions,which is the minimum effectiveness required by Ecodesign(in the EU).For the examined exchangers,the effectiveness ranges from 66.5%to 83.3%,depending on the boundary conditions and geometric parameters of the *** highest sensible effectiveness is achieved by heat exchangers with the largest heat exchange surface Ac;on the other hand,these wheels have the largest pressure *** paper discusses the use of a simplifiedε-nTU correlation model for the HVAC systems(typically C*=1).The correlation model and CFD results were compared and found to be different from each *** results of the CFD simulation were compared with measurements to prove that the proposed simulation method can predict the behaviour of the real heat exchanger as a *** was demonstrated that the sensible effectiveness and pressure loss of the rotary heat exchanger predicted by the CFD simulations correspond well to the measured values within the measurement uncertainty±1.3%.The proposed method can be used for the comparison of different rotary regenerative heat exchangers before their manufacturing and for verification that they meet the EU Ecodesign requirements set by the current *** reduces the cost of the initial optimisation and testing of new designs.

关键词： rotary heat exchanger heat wheel microchannel heat recovery sensible effectiveness pressureloss computer fluid dynamics experiment

Is Chloroplast Movement in Tobacco Plants Influenced Systemically after Local Illumination or Burning Stress?

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Journal of Integrative Plant Biology 2008年第10期50卷 1292-1299页

作者： Jan nau Monika rolencov vladim.ra Hlavkov Laboratory of Biophysics Department of Experimental Physics Palacky' University tr. Svobody 26 77146 Olomouc Czech Republic

Chloroplast movement has been studied in many plants mainly in relation to the local light, mechanical or stress effects. Here we investigated possible systemic responses of chloroplast movement to local light or burning stress in tobacco plants （nicotisna tabacum cv. Samsun）. Chloroplast movement was measured using two independent methods： one with a SPAD 502 Chlorophyll meter and another by collimated transmittance at a selected wavelength （676 nm）. A sensitive periodic movement of chloroplasts was used in high or low （2 000 or 50 μmol/m2 per s photosynthetically active radiation, respectively） cold white light with periods of 50 or 130 min. Measurements were carried out in the irradiated area, in the non-irradisted area of the same leaf or in the leaf located on the stem below the irradiated or bumed one. no significant changes in systemic chloroplast movement in non-irradiated parts of the leaf and in the non-treated leaf were detected. Our data indicate that chloroplast movement in tobacco is dependent dominantly on the intensity and spectral composition of the incident light and on the local stimulation and state of the target tissue. no systemic signal was strong enough to evoke a detectable systemic response in chloroplast movement in distant untreated tissues of tobacco plants.

关键词： buming chloroplast movement irradiance systemic response tobacco.

Computational simulation methods for fiber reinforced composites

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Frontiers of Structural and Civil Engineering 2010年第3期4卷 396-401页

作者： vladim.r KOMPIŠ Zuzana MUrČInKOVÁ Sergey rJASAnOW richards GrZIBOVSKIS QinghuaQIn DSSI j.s.c.Wolkrova 482105 BratislavaSlovakia Technical University Košice Faculty of Manufacturing TechnologiesŠtúrova 3108001 PrešovSlovakia Department of Mathematics and Computer Science University of SaarlandSaarbrückenGermany Department of Engineering Australian National UniversityACTAustralia

Trefftz-finite element method(Trefftz-FEM),adaptive cross approximation BEM(ACA BEM)and continuous source function method(CSFM)are used for the simulation of composites reinforced by short fibers(CrSF)with the aim of showing the possibilities of reducing the problem of complicated and important interactions in such composite materials.

关键词： Trefftz-finite element method(Trefftz-FEM) adaptive cross approximation BEM(ACA BEM) method of continuous source functions composite materials short fibers

Possibilities of GPS Kinematic Measurements for Geological Survey in East Slovakia

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Geo-Spatial Information Science 2002年第4期5卷 21-25页

作者： vladim.r Sedlák Viera Huríková Sona Molíková Department of Geodesy and Geophysics The Technical University of Kosice Park Komenskeho 19 SK-043 84 Kosice Slovakia

This paper deals with transformation procedures for observed GPS data from the world geodetic system WGS84 into the national geodetic grid datum SUTCn （system of united trigonometric cadaster network） and Baa（the Baltic Sea after adjustment）.Transformation from WGS84 into SUTCn is performed most frequently by means of the 7element Helmert transformation with three identical *** network was adjusted by two ways.

关键词： kinematic GPS technology 3D coordinate transformations free adjustment adjustment with constraints

Entropy—A Universal Concept in Sciences

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natural Science 2014年第7期6卷 552-564页

作者： vladim.r Majerník Mathematical Institute Slovak Academy of Sciences Bratislava Slovakia

Entropy represents a universal concept in science suitable for quantifying the uncertainty of a series of random events. We define and describe this notion in an appropriate manner for physicists. We start with a brief recapitulation of the basic concept of the theory probability being useful for the determination of the concept of entropy. The history of how this concept came into its to-day exact form is sketched. We show that the Shannon entropy represents the most adequate measure of the probabilistic uncertainty of a random object. Though the notion of entropy has been introduced in classical thermodynamics as a thermodynamic state variable it relies on concepts studied in the theory of probability and mathematical statistics. We point out that whole formalisms of statistical mechanics can be rewritten in terms of Shannon entropy. The notion “entropy” is differently understood in various science disciplines: in classical physics it represents the thermodynamical state variable;in communication theory it represents the efficiency of transmission of communication;in the theory of general systems the magnitude of the configurational order;in ecology the measure for bio-diversity;in statistics the degree of disorder, etc. All these notions can be mapped on the general mathematical concept of entropy. By means of entropy, the configurational order of complex systems can be exactly quantified. Besides the Shannon entropy, there exists a class of Shannon-like entropies which converge, under certain circumstances, toward Shannon entropy. The Shannon-like entropy is sometimes easier to handle mathematically then Shannon entropy. One of the important Shannon-like entropy is well-known Tsallis entropy. The application of the Shannon and Shannon-like entropies in science is really versatile. Besides the mentioned statistical physics, they play a fundamental role in the quantum information, communication theory, in the description of disorder, etc.

关键词： Probability Uncertainty Shannon Entropy Shannon-Like Entropies

The Effect of Different Diet on Saliva

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Spectral Analysis review 2017年第4期5卷 37-48页

作者： vladim.ra Tomecková Kristína Krajcíková Slavomíra Dolinská vladim.r Komanický Tomás Samuely Department of Medical and Clinical Biochemistry Faculty of MedicinePavol Jozef Safárik University in KosiceKosiceSlovak Republic Institute of Physics Faculty of SciencePavol Jozef safárik University in KosiceKosiceSlovak Republic

The aim of this scientific research was to study the influence of various diets (ketogenic, low carb, mixed) on teeth and saliva structure of healthy individuals. The health condition of teeth and the influence of diet (sweets, water intake) were investigated using the questionnaires which were statistically processed by descriptive and inductive statistics. Saliva was examined using synchronous fluorescent fingerprint (SFF) and atomic force microscopy (AFM). The statistical evaluation of answers of respondents using the questionnaires about intake of sweets in their diet showed significant influence of sugars on formation of tooth decay of diet. The intake of water (volume and frequency) did not show significant influence on formation of tooth decay. Endogenous fluorescence and surface structure of saliva differed in healthy subjects with different diet. The most organized surface structure showed low carb diet (without crystals). The least organized surface structure showed ketogenic diet with the big crystals (1 - 2 μm). Untraditional methods (SFF and AFM) enable the new, sensitive and quick analysis of the mixture of saliva. Saliva of individuals with low carb diet showed the most organized structure. Low content of sugar in diet is important possibility of the prevention before dental carries.

关键词： Low Carb Diet Mixed Diet Ketogenic Diet Saliva Synchronous Fluorescence Fingerprint Atomic Force Microscopy

nanoscale architecture of ceria-based model catalysts: Pt-Co nanostructures on well-ordered CeO_(2)(111) thin films

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Chinese Journal of Catalysis 2020年第6期41卷 985-997页

作者： Yaroslava Lykhach TomásSkála Armin neitzel nataliya Tsud Klára Beranová Kevin CPrince vladim.r Matolín Jorg Libuda Interface research and Catalysis Erlangen Catalysis Resource CenterFriedrich-Alexander-Universit?t Erlangen-NürnbergEgerlandstrasse 391058 ErlangenGermany Charles University Faculty of Mathematics and PhysicsDepartment of Surface and Plasma ScienceV Hole?ovi?kách 218000 PragueCzech Republic Elettra-Sincrotrone Trieste SCpA Strada Statale 14km 163.534149 Basovizza-TriesteItaly

We have prepared and characterized atomically well-defined model systems for ceria-supported Pt-Co core-shell catalysts. Pt@Co and Co@Pt core-shell nanostructures were grown on well-ordered CeO2(111) films on Cu(111) by physical vapour deposition of Pt and Co metals in ultrahigh vacuum and investigated by means of synchrotron radiation photoelectron spectroscopy and resonant photoemission spectroscopy. The deposition of Co onto CeO2(111) yields CoCeO2(111) solid solution at low Co coverage(0.5 ML), followed by the growth of metallic Co nanoparticles at higher Co coverages. Both Pt@Co and Co@Pt model structures are stable against sintering in the temperature range between 300 and 500 K. After annealing at 500 K, the Pt@Co nanostructure contains nearly pure Co-shell while the Pt-shell in the Co@Pt is partially covered by metallic Co. Above 550 K, the re-ordering in the near surface regions yields a subsurface Pt-Co alloy and Pt-rich shells in both Pt@Co and Co@Pt nanostructures. In the case of Co@Pt nanoparticles, the chemical ordering in the near surface region depends on the initial thickness of the deposited Pt-shell. Annealing of the Co@Pt nanostructures in the presence of O2 triggers the decomposition of Pt-Co alloy along with the oxidation of Co, regardless of the thickness of the initial Pt-shell. Progressive oxidation of Co coupled with adsorbate-induced Co segregation leads to the formation of thick CoO layers on the surfaces of the supported Co@Pt nanostructures. This process is accompanied by the disintegration of the CeO2(111) film and encapsulation of oxidized Co@Pt nanostructures by CeO2 upon annealing in O2 above 550 K. notably, during oxidation and reduction cycles with O2 and H2 at different temperatures, the changes in the structure and chemical composition of supported Co@Pt nanostructures were driven mainly by oxidation while reduction treatments had little effect regardless of the initial thickness of the Pt-shell.

关键词： Core-shell nanoparticles Model catalyst Pt-Co Cerium oxide Chemical ordering Synchrotron radiation photoelectron spectroscopy