ABSTRACTS

Proceedings p. 5-8

G. H. HESS – AUTHOR OF „LAW OF CONSTANT SUM OF HEATS OF REACTION„

Ivo Proks

Ústav anorganickej chémie SAV, Dúbravská cesta 9, 842 36 Bratislava, Slovak Republic

Biography and profesional life of D.G. Hess with emphasis on his contributions in the field of thermodynamics and calorimetry

Proceedings p. 9-12

ANOMALOUS VALUES OF THERMOPHYSICAL NONEQUILIBRIUM STRUCTURES EXAMINED BY PULSE METHOD

Ľ. Kubičár^A, V. Boháč^A, V. Vretenár^A, Z. Hrabě^B, Ján Pach^B, J Kozánková^B

^AFyzikálny ústav SAV, Dúbravska cesta 9, 842 28 Bratislava, Slovak Republic

^BKatedra skla a keramiky, Chemickotechnologická fakulta STU, Radlinského 9, 812 37 Bratislava, Slovak Republic

The contribution reports on the results of the study of anomalous values of thermophysical parameters on the microstructures formed in the course of sintering. The experiments were carried out with E-glass and Al₂O₃ , using a pulse transition method. It has been concluded that the anomalous values result from the generation of density fluctuations during sintering.

Proceedings p. 13-16

THERMOPHYSICAL PROPERTIES OF PRESSED AVICEL PELLETS EXAMINED BY PULSE METHOD

V.Boháč, Ľ.Kubičár, M.Řehula^*, V.Vretenár

Fyzikálny Ústav SAV, Dúbravská ceta 9, 842 28 Bratislava, Slovak Republic

Farmaceutická fakulta v Hradci Králové, Karlova Univerzita, Czech Republic

Pulse transition methods has been used to study thermophysical properties of Avicel pressed under different pressures. Two effects have been discerned. The first one was relaxation of the material at increased temperatures. The second, observed on thermal cycling of the material in thermal analysis regime , were changes in the system of bonds between cellulose fibers.

Proceedings p. 17-20

HIGH-TEMPERATURE DYNAMIC THERMOMECHANICAL ANALYSIS

^aEva Černošková, ^bZdeněk Černošek, ^bJana Holubová

^aSpolečná laboratoř chemie pevných látek AV ČR a Univerzity Pardubice,

Studentská 84, Pardubice, CZ-532 10, e-mail: eva.cernoskova@upce.cz,Czech Republic

^bVýzkumné centrum Univerzity Pardubice a Ústavu anorganické chemie AV ČR

Fakulta chemicko-technologická, Univerzita Pardubice, nám. Legií 565,

Pardubice, CZ-532 10, Czech Republic

The complex modulus in flexion of NBS 711 glassy fibers was investigated using dynamic thermomechanical analyzer (DTMA) in the large temperature area from the room to the supercooled liquid region through the glass transition area. The real part of the dynamic modulus, E’, as well as the imaginary one E’’ and loss angle tand were obtained and studied depending on frequencies and heating rates, as well. Obtained results were compared with the static thermomechanical analysis (TMA), viscosity measurements and results obtained with help of StepScan DSC method.

Proceedings p. 21-24

ENTHALPIC RELAXATION OF GLASSES

Jana Holubová^A , Zdeněk Černošek^A , Eva Černošková^B

^A Katedra obecné a anorganické chemie, Fakulta chemicko-technologická,

Univerzita Pardubice, nám. Legii 565, Pardubice, CZ-532 10, Czech Republic

^B Společná laboratoř chemie pevných látek AV ČR a Univerzity Pardubice,

Studentská 84, Pardubice, CZ-532 10, Czech Republic

The isothermal structural relaxation has been studied on model glass with perfectly defined thermal history by differential scanning calorimetry (DSC) and the computer simulation of obtained DSC curves was based on Tool-Narayanaswamy-Moynihan model with Kohlrausch-William-Watts relaxation function. The parameter of non-exponentiality, b, and the enthalpy change, DH, have been evaluated and their time and thermal dependencies have been discussed. It was found that b is both temperature and time dependent. When the relaxed glass has reached the pseudo-equilibrium state the corresponding limit enthalpy change, DH_eq, was found to be less than those defined by the linear extrapolation from higher temperatures.

Proceedings p. 25-28

ENTHALPIC RELAXATIONS AND GLASS TRANSITION

Zdeněk Černošek^A, Jana Holubová^A, Eva Černošková^B

^AVýzkumné centrum Univerzity Pardubice a Ústavu anorganické chemie AV ČR, Univerzita Pardubice, nám. Legii 565, Pardubice, CZ-532 10, Czech Republic

^BSpolečná laboratoř chemie pevných látek AV ČR a Univerzity Pardubice

Univerzita Pardubice, Studentská 84, Pardubice, CZ-532 10, Czech Republic

The glass transition was studied by a new stepwise DSC technique on the bulk As₂Se₃ and As₂S₃ glasses. The glass transition was found to be a superposition of two parts: a reversible or thermodynamic component, reflecting temperature changes of vibrational amplitudes, and an irreversible or kinetic process, so-called enthalpy relaxation. The value of the glass transition temperature, T_g, determined from the thermodynamic part of the glass transition was found to be independent on both the heating/cooling rate and the thermal history of glass. The T_g depends only on the chemical composition of the glass and thus it could be regarded as a material constant. Therefore the heating/cooling rate dependence of T_g, known from DSC or DTA measurements, is caused by kinetic process with relaxation time dependent on structure and temperature.

Proceedings p. 29-32

KINETICS OF NONISOTHERMAL CRYSTALLIZATION OF POLYMERS

Jaroslav Kratochvíl, Antonín Sikora

Ústav makromolekulární chemie AV ČR, Heyrovského nám. 2, 162 06 Praha 6, Czech Republic

Nonisothermal crystallization of poly(N-methyldodecanolactam) MPA was studied by DSC method in the range of cooling rates 2-40K/min. Two kinetic models were used to calculate kinetic parameters from relative crystallinities. The results obtained by the Avrami method indicate a two-dimensional growth of crystallites combined with heterogeneous nucleation in the initial phase of the crystallization. The Tobin method, which characterizes intermediate phase of the process, indicates a possible partial occurence of homogeneous nucleation. The activation energies of the nonisothermal crystallization were calculated by the Kissinger method.

Proceedings p. 33-36

STUDY OF POLYETHYLENE OXIDE MELTING BY TEMPERATURE -MODULATED DSC

A.Sikora^A, V. B. Dolgoshey^B, J. Baldrian^A, J. Kratochvíl^A

^A Ústav makromolekulární chemie AV ČR, Heyrovského nám. 2, 16202 Praha 6, Czech Republic

^B Institute of Macromolecular Chemistry National Academy of Sciences of Ukraine, 48 Kharkiv Chausse, 02160 Kyiv, Ukraine

Temperature-modulated differential scanning calorimetry (TMDSC) provides information about dynamics of the processes taking place in the studied system. In the present contribution the results of the study of melting of polyethylene oxide oligomer (PEO3000) are discussed.

Proceedings p. 37-40

THERMOMECHANICAL ANALYSIS OF NBS711 GLASS TRANSITION – A COMPARISON OF MAZURIN’S AND MOYNIHAN’S APPROACH

Mária Chromčíková, Miroslava Krajčíková

Joint Glass Laboratory of Institute of Inorganic Chemistry of SAS and University of Trenčín, Trenčín, Slovak Republic

The structural relaxation of NBS711 glass studied by thermodilatometry and thermomechanical analysis was well described using the mathematical models Mazurin’s and Moynihan’s. The mathematical models are based on KWW relaxation function with relaxation time proportional to instantaneous viscosity. The non-linear regression of experimental data enabling the estimation of relaxation parameters together with the thermal expansion coefficient of glass,a_g, and metastable melt,a_m, was proposed. The structural relaxation of the glass was well described by the used non-linear regression mathematical model.

Proceedings p. 41-44

STUDY OF CRYSTALLIZATION OF AMORPHOUS TiO₂

Jana Shánělová^A, Daniel Švadlák^A, Jiří Málek^B

^A Katedra fyzikální chemie, Fakulta chemicko-technologická, Univerzita Pardubice, Nám. Čs. Legií 565, Pardubice 532 10, Czech Republic

^B Společná laboratoř chemie pevných látek AV ČR a Univerzity Pardubice, Studentská 84, Pardubice 532 10, Czech Republic

Amorphous TiO₂·0.72H₂O was used as model compound. Nonisothermal crystallization at heating rates of 5-20K/min was measured by DSC method. Data so obtained were used to calculate the enthalpy of crystallization of pure TiO₂, 165.9 J/g, activation energy of the crystallization, 276.4 kJ/mol and frequency factor ln (A/s^-1) = 43.3. Kinetic models tested were JMA (m = 1.128) and SB (M = 0.07, N = 0.94).

Proceedings p. 45-48

STUDY OF KINETICS OF ISOTHERMAL CRYSTALLIZATION OF GE₃₈S₆₂ GLASS

Pavla Pustková ^A, Jana Shánělová ^B

^AUniverzita Pardubice, Fakulta chemicko-technologická, Katedra anorganické technologie, Nám. Čs. legií 565, 532 10 Pardubice, Czech Republic

^BUniverzita Pardubice, Fakulta chemicko-technologická, Katedra fyzikální chemie, Nám. Čs. legií 565, 532 10 Pardubice, Czech Republic

Kinetics of crystallization of Ge₃₈S₆₂ glass under isothermal conditions was studied by DSC method. The process of isothermal crystallization of this glass can be described by the so called autocatalytic kinetic model with the following kinetic exponents M = 0,81 ± 0,07 and N = 0,79 ± 0,08. Enthalpy of the crystallization is -86 ± 7 J/g and the activation energy of Ge₃₈S₆₂ glass crystallization is 291 ± 6 kJ/mol.

Proceedings p. 49-52

EFFECT OF TiO₂ ON THERMAL BEHAVIOUR OF BORON SILICATE GLASSES

Petr Mošner^A, Ladislav Koudelka^A, Bořivoj Hlaváček^B

^AKatedra obecné a anorganické chemie, ^BÚstav polymerních materiálů, Czech Republic

Univerzita Pardubice, Fakulta chemicko-technologická, 532 10 Pardubice, Czech Republic

A series of glasses of the system 50PbO-10B₂O₃-40P₂O₅+xTiO₂, where x = 0-16 mol.% TiO₂ were prepared. Thermal behaviour of these glasses was studied by differential thermal and thermomechanical analyses. It was found that the addition of TiO₂ increases T_g from 391°C for the glass 50PbO-10B₂O₃-40P₂O₅ up to 514°C for the glass containing 16 mol.% TiO_2. In glasses containing 0-6 mol. % TiO_2, the bulk nucleation is prevailing process. The most thermaly stable were glasses with 4 mol.% TiO_2.

Proceedings p. 53-56

THERMOCHEMICAL PROPERTIES OF Bi₂CuO₄

David Sedmidubský^A, Aleš Strejc^A, Květoslav Růžička^B Jindřich Leitner^C

^AÚstav anorganické chemie, VŠCHT Praha, Technická 6, 16628 Praha 6, Czech Republic

^BÚstav fyzikální chemie, VŠCHT Praha, Technická 6, 16628 Praha 6, Czech Republic

^CÚstav inženýrství pevných látek, VŠCHT Praha, Technická 6, 16628 Praha 6, Czech Republic

Results of heat capacity (DSC method, 300-570 K) and heat content (DROP method, 670-970K)  measurements of the mixed oxide Bi₂CuO₄ are presented. The heat of dissolution in the melt 2PbO.B₂O₃ was measured with the aim to determine the value of standard enthalpy of formation at 298.15K. From these and pertinent literature data, thermodynamic functions of Bi₂CuO₄ for 298.15 – 1100 K region were calculated.

Proceedings p.57-60

HIGH -TEMPERATURE HORIZONTAL DILATOMETER

Branislav Karafa, Igor Štubňa, Libor Vozár

Univerzita Konštantína Filozofa, Katedra fyziky, Tr. A. Hlinku 1, 949 74 Nitra,

Slovak Republic

Horizontal differential dilatometer was developed for measuring the coefficient of linear thermal expansion of solid samples. The working temperature interval of the dilatometer is 20 – 1200°C. The apparatus consists of alumina rods placed across the oven. The sensor based on induction principle measures the sample prolongation. The level of compensation the dilatometer‘s systematic errors was studied performing the test measurements.

Proceedings p.61-64

PHOTOTHERMAL METHODS OF THERMALCONDUCTIVITY MEASUREMENTS

Štefan Valovič, Gabriela Smetanková

Katedra fyziky FPV, Univerzita Konštantína Filozofa, Tr.A.Hlinku 1, SK-94974 Nitra, Slovak republic

The contribution discusses basic photothermal methods of measuring the thermal diffusivity of solids. A special attention is given to the standard flash method, the flash method with extended pulse, the flash method with repeated pulses, photothermal radiometry, the method based on mirage effect and photoreflectance method.

Proceedings 65-68

TEST STANDARD EN ISO 1716 AS A PART OF BUILDING PRODUCTS CLASSIFICATION

Jiří Socha, Pavel Vaniš,

PAVUS, a.s., Praha, Czech Republic

The European standard dealing with the determination of heats of combustion of building products is described.

Proceedings 69-72

STUDY OF PUZZOLANIC ACTIVITY OF ALUMINOSILICATE MATERIALS BY THERMOCHEMICAL METHOD

Pavla Rovnaníková

Ústav chemie FAST VUT, Žižkova 17, 662 37 Brno, Czech Republic

Methods for determining puzzolanic activity of materials that are added to mixture for lime plasters as active components is reviewed and evaluated. The results showed that the most active addend is brick powder, while metakaoline shows lower puzzolanic activity.

Proceedings 73-76

CALORIMETER INVESTIGATION OF THE HYDRAULICITY OF Cr(VI)-BEARING PHASE IN CEMENT

Martin Palou, Ján Majling^a and Ayadi Azzedine^b

^a Faculty of Chemical and Food Technology, Slovak University of Technology

Radlinského 9, 812 37 Bratislava, Slovak Republic

^bFaculté des Sciences de l´Ingénieur, Université de Bourmedes 3500 Bourmedes - Algerie

Conduction calorimeter has been used to assess the hydraulicity of C₄A₃Cr^(*), the phase analog to C₄A₃ found in sulfoaluminate cements. C₄A₃Cr, synthesized at 1250 °C, is well- crystallized phase. It seems to be hydraulically latent at an earlier period of hydration, but the reaction is stimulated in the presence of C₄A₃ or C, as determined by conduction calorimeter. The total heat expressed at hydration is nearly the same for all specimens , but the rate of heat evolution depends on the ratio of C₄A₃/C₄A₃Cr phases.

Proceedings 77-80

MEASUREMENT OF THERMAL AND MOISTURE PARAMETERS OF PLASTERS AND WATER VAPOUR RETARDANTS FOR SYSTEMS WITH INTERNAL THERMAL INSULATION

Milena Jiřičková ^A, Robert Černý ^A

^A ČVUT, Stavební fakulta, katedry stavební mechaniky, Thákurova 7, 166 29 Praha 6, Czech Republic

The present work deals with the experimental determination of thermal and hygric parameters of both commercial and newly developed plasters and water vapour retarders. A brief overview is presented of measured physical parameters, measured apparatus and analyzed materials. Experimental conditions are defined and the way of preparing is described. The tested materials that are very suitable for using in interior thermal insulation systems are chosen.

Proceedings 81-84

OPTIMIZATION OF MATERIAL PARAMETERS OF MOISTURE TRANSPORT IN MATERIALS WITH INTERNAL THERMAL INSULATION

Jiří Maděra^A, Robert Černý^A

^A ČVUT, Stavební fakulta, katedra stavební mechaniky, Thákurova 7, 16629 Praha 6, Czech Republic

The paper describes optimization of thermal moisture behavior of the outer wall with internal thermal insulation that is based on the changes in material moisture properties of a water vapour retardant placed between the thermal insulation and the bearing brick construction. Two types of mineral wool produced by Rockwool and designated as CL and DU have been used. The first one was hydrophobized, the second contained hydrophilic additives. Heat and moisture transport was solved with the aid of a computer programme DELPHIN 4.2 by which temperature, relative air moisture and over hydroscopic moisture for the period of several years have been calculated.

Proceedings 85-88

MEASUREMENT OF HEAT-MOISTURE PARAMETERS IN BRICK WALL WITH INTERNAL THERMAL INSULATION UNDER DIFFERENTIAL CLIMATE CONDITIONS

Zbyšek Pavlík , Robert Černý

ČVUT, Stavební fakulta, katedry stavební mechaniky, Thákurova 7, 166 29 Praha 6, Czech Republic

Measurement of hygrothermal parameters of a brick wall with an interior contact thermal insulation system based on mineral wool under differential climate conditions is presented in the paper. Methods for measuring individual physical parameters and the arrangement of the experiment as such are described in detail. Finally are summarized the results of the measurements and perspectives of further utilization of the chosen measuring system are outlined.

Proceedings 89-92

MEASUREMENT OF THERMAL DIFFUSIVITY COEFFICIENTS OF GLASS CEMENTS AT HIGH TEMPERATURES

Jitka Poděbradská ^A, Jan Toman^B, Robert Černý ^A

^A ČVUT, Stavební fakulta, katedra stavební mechaniky, Thákurova 7, 166 29 Praha 6, Czech Republic

^B ČVUT, Stavební fakulta, katedra fyziky, Thákurova 7, 166 29 Praha 6, Czech Republic

The paper reports of the method for measuring thermal diffusivity coefficients of nonhomogeneous materials at high temperatures. The method is based on determination of temperature fields in the sample heated from one side and subsequent solution of the inverse problem of heat conduction. The applicability of the method has already been verified with concretes. In the present work it is applied to the determination of thermal diffusivity coefficients of glass cement composites.

Proceedings 93-96

DETERMINATION OF HEAT STABILITY AND THERMAL CONDUCTIVITY COEFFICIENT OF SIDE BRICKS

Jan Toman^A, Jaroslav Pavlík^B, Robert Černý^B

^AČeské vysoké učení technické, Fakulta stavební, Katedra fyziky,

Thákurova 7, 16629 Praha 6, Czech Republic

^BČeské vysoké učení technické, Fakulta stavební, Katedra stavební mechaniky,

Thákurova 7, 16629 Praha 6, Czech Republic

In this paper is described the determination of thermal stability and thermal conductivity coefficient of side bricks made from two kinds of materials. The thermal stability was determined for three temperature ranges: 1. from –45 °C to +180 °C, 2. < -45 °C, 3. > 180 °C. The samples were visually analyzed and the touch test was done during the measurements. The thermal conductivity coefficient were measured by the ISOMET device, model 2104.

Proceedings 97-100

MEASUREMENT OF CHANGES IN LENGTH OF CEMENT WOOD IN MEDIA OF DIFFERENT MOISTURE CONTENT

Jan Toman^A,Eva Mňahončáková^A, Robert Černý^B

^AKatedra fyziky Stavební fakulty ČVUT, Thákurova 7, 166 29 Praha 6, Czech Republic

^BKatedra stavební mechaniky Stavební fakulty ČVUT, Thákurova 7, 166 29 Praha 6, Czech Republic

The contribution deals with of the length changes caused by placing the material under study in media containing different content of moisture and during the study of the effects of protective coatings.

Proceedings 101-104

MEASUREMENT OF MOISTURE CONDUCTIVITY COEFFICIENT OF GLASS CEMENT AFTER ITS HEAT AND TENSILE STRESS

Jan Toman^A, Michaela Totová^B, Robert Černý^B

^A Katedra fyziky stavební fakulty ČVUT, Thákurova 7, 166 29 Praha 6, Czech Republic

^B Katedra stavební mechaniky stavební fakulty ČVUT, Thákurova 7, 166 29 Praha 6, Czech Republic

The object of the present work was to ascertain moisture conductivity changes of the developed composite materials (cements containing different additives, enforced with carbon fibers) caused by their high temperature heating and by tensile stress to stress values close to their breaking strength.

Proceedings 105-108

MEASUREMENT OF MOISTURE IN CEMENT PASTE BY MICROWAVE METHOD

Jaroslav Pavlík, Vratislav Tydlitát, Robert Černý

České vysoké učení technické, Fakulta stavební, Katedra stavební mechaniky,

Thákurova 7, 16629 Praha 6, Czech Republic

The contribution presents a microwave impulse method for moisture measurements and its application for to monitoring of the content of unbound water at the early stage of hydration in the cement paste. The major part of the paper is concerned with the calibration of the measurement by this method.

Proceedings 109-110

ON USE OF DTA IN SYNTHESIS OF INORGANIC PIGMENTS

Petra Šulcová

Katedra anorganické technologie, Fakulta chemicko-technologická, Univerzita Pardubice, nám. Čs. legií 565, 532 10 Pardubice, Czech Republic

Methods of thermal analysis (TG, DTA) can be used to define conditions for the synthesis of inorganic pigments as it includes the calcination of reaction mixtures consisting suitable starting materials. Thermal analysis thus provides initial information about temperature of formation of these pigments and make it possible to obtain pigment samples in amounts sufficient for subsequent pigment-application tests.

Proceedings 111-112

STUDY OF CALCIUM OXALATE HYDRATES BY CALORIMETRIC METHODS

Galina Sádovská¹ a Gert Wolf²

¹Univerzita Pardubice, Katedra anorganické technologie, Czech Republic

²TU – Freiberg, Institut für Physikalische Chemie, SRN

The enthalpies of dissolution of calcium oxylate hydrates were calculated with the aid of combinations of equations, the enthalpy of reactions wich could be easily dedtermined. These values were further used in calculating DH_r corresponding to 1 mol of H20 between individual hydrates. The same procedure has been used also with dehydration enthalpies of the hydrates obtained in DSC measurements.

Proceedings 113-114

STUDY OF SOLUBILITY OF STRUVITE AND NEWBERYITE BY CALORIMETRIC METHODS

Zdeněk Sádovský, Galina Sádovská a David Bíbrlík

Univerzita Pardubice, Katedra anorganické technologiem, Czech Republic

The method of isoperibolic calorimetry was used to estimate the solubility of struvite and newberyite in medium simulating physiological conditions.

Proceedings 115-118

DEHALOGENATION OF POLYCHLORINATED PHENOLS

Michal Bureš^A, Vladimír Pekárek^B

^AÚstav fyzikální chemie, Vysoká škola chemickotechnologická, Technická 5, 166 28 Praha 6, Czech Republic

^B Ústav chemických procesů AV ČR, Rozvojová 135, 165 02Praha 6, Czech Republic

The aim of this study is thermodynamic analysis of the gas phase dehalogenation of polychlorinated phenols in the presence of steam and solid copper. The purpose of this study is a thermodynamical interpretation of the mechanism of dehalogenation processes and its comparison with experimental kinetic data.

Proceedings 119-122

THE EFFECT OF LIGHT FACTOR ON ENERGY VALUES OF SEVERAL HERB SPECIES of SPRUCE ECOSYSTEMS

Margita Kováčová, Ján Kukla, Branislav Schieber

Ústav ekológie lesa SAV, Štúrova 2, 960 53 Zvolen, Slovak republic

The paper presents the results of the research from Bielovodská dolina (the High Tatras) on the bark beetles damaged and undamaged research monitoring plots. The parameters of the energy of selected herb species showed higher values in the insect – damaged area. Energy values related to 1 gramme of the herb individual moved from 18.260 kJ.g^-1 to 21.039 kJ.g^-1 (the differences between monitoring plots changed from 0.2 to 3%). Energy content calculated to the mass of individual fluctuated from 0.112 kJ.individual^-1 to 41.037 kJ. individual^-1 (the differences changed from 41 to 112% ).

Proceedings 123-126

ENERGY CONTENT IN TOMATOES (Lycopersicum esculentum mill.) DURING ONTOGENESIS

Helena Hniličková^A, Josef Duffek^A, František Hnilička^B

Česká zemědělská univerzita v Praze, ^Akatedra zahradnictví, ^Bkatedra botaniky a fyziologie rostlin, Kamýcká 129, 165 21 Praha 6 - Suchdol, Czech Republic

The content of energy during growing season has been stable for both species in both test years. In average, the tomato plant contained 13,17 až 13,82 kJ.g^-1 DM net energy. Of individual parts, the most energy was accumulated in fruits. No difference in the amount of accumulated energy has been observed between both species.

Proceedings 127-130

ACCUMULATION OF ENERGY IN AMARANTH PLANTS (amaranthus sp.) AND ITS UTILIZATION AS LEAF VEGETABLES

František Hnilička¹, Kamila Holubová², Helena Hniličková³

¹ Česká zemědělská univerzita, katedra botaniky a fyziologie rostlin, Kamýcká 129, 165 21

Praha 6 - Suchdol, Česká republika, hnilicka@af.czu.cz, Czech Republic

² Česká zemědělská univerzita, Institut tropického a subtropického zemědělství, Kamýcká 129, 165 21 Praha 6 - Suchdol, Czech Republic

³ Česká zemědělská univerzita, katedra zahradnictví, Kamýcká 129, 165 21 Praha 6 - Suchdol,

Czech Republic

Four most important genotypes of Amaranth (Amaranthus sp.) were studied two years (2000-1) for A. aureus, A. caudatus and A. cruentus. Seven energy contents and dry mass of leaves were determined during growing season. With Amaranthus cruentus, the average heat of combustion was 13.91 kJ.g^-1 while with Amaranthus aureus the content of the matter rich in energy was 13.48 kJ.g^-1.

Proceedings 131-134

The influence OF LOW TEMPERATURES ON ENERGY ACCUMULATION IN LEAVES OF YOUNG winter WHEAT PLANTS

František Hnilička¹, Jiří Petr², Radek Vavera²

¹ Česká zemědělská univerzita, katedra botaniky a fyziologie rostlin, Kamýcká 129, 165 21

Praha 6 - Suchdol, Czech Republic, hnilicka@af.czu.cz

² Česká zemědělská univerzita, katedra rostlinné výroby, Kamýcká 129, 165 21 Praha 6 - Suchdol, Czech Republic

The stress effect of low temperatures was studied for the following wheat cultivars: Ludwig, Vlasta, Sepstra, Apache, Corsaire, Complet, Samanta, Batis, Contra, Semper, Drifter and Windsor. The lowest average net energy content was recorded for the Apache cultivar (10.09 kJ.g^-1) and the highest values of net energy for the Ludwig (12.18 kJ.g^-1) and Vlasta cultivars (12.21 kJ.g^-1). The most considerable decrease of net energy content was caused by temperatures –14.1 °C - –18.1 °C . On the other side, the lowest depression was caused by temperatures –6.0 °C - –7.7 °C.

Proceedings 135-138

DAILY ENERGY AND DRY MATTER INCREments in VEGETATIVE AND GENERATIVE PARTS OF HOP plants DURING growing SEASON

Helena Hniličková^A, František Hnilička^B, Vratislav Novák^B

Česká zemědělská univerzita v Praze, ^Akatedra zahradnictví, ^Bkatedra botaniky a fyziologie rostlin, Kamýcká 129, 165 21 Praha 6 - Suchdol, Czech Republic

The irrigation of hop plants ensures an optimum development of the habit of hop and intense metabolism that lead to the corresponding crop of hop heads. The watered hop plant shows higher daily dry matter increments compared to the nonirrigated plant. The knowledge of the moisture consumption of hop plant during vegetal season provides support for the need of additional irrigation of hop during June and July, which gave the higher daily energy increments for watered plants.

Proceedings 139-142

TEMPERATURE DEPENDENCE OF ELECTRICAL PROPERTIES OF BIOLOGICAL MATERIALS

Zuzana Hlaváčová

Katedra fyziky, Slovenská poľnohospodárska univerzita v Nitre, Tr. A. Hlinku 2, Nitra, Slovak Republic

Electrical properties are most often used in determining the moisture content of materials. In addition to the moisture content, these properties are influenced also by other factors such as temperature, bulk density in the case of loose materials and the volume mass in the case of porous substances, or by sorption properties, to name some of them. The precise measurements require the knowledge of dependencies of electrical properties on temperature and the use of these data in making corrections of the electrical measuring instruments. The temperature dependencies of resistivity and relative permitivity are reported in the present work.

Proceedings 143-146

THERMAL AND TEMPERATURE CONDUCTIVITY OF CORN MASS

Monika Božiková

Slovenská poľnohospodárska univerzita , katedra fyziky, Tr. A Hlinku 2, 949 76 Nitra, Slovak Republic

The paper is concerned with thermophysical properties of maize and wheat flours. The results of the thermal conductivity and temperature conductivity measurements in dependence on the moisture content and bulk density are presented.

Proceedings 147-150

CALORIMETRIC STUDY OF THE EFFECT OF CHEMICAL ADDITIVES ON THE REACTIVITY OF COAL TOWARDS OXYGEN

Boleslav Taraba, Rudolf Peter

Ostravská univerzita, katedra chemie PřF, ul. 30. dubna 22, 70103 Ostrava, Czech Republic

The contribution deals with the evaluation of chemical substances as possible inhibitors of coal oxidation, using dip and pulse flow calorimetry. This approach provides a complex description of the behaviour of the system: coal-additive-oxygen.

Proceedings 151-154

EFFECT OF SOME FACTORS ON TRANSPORT PROCESSES IN BIOLOGICAL MATERIALS

Vlasta Vozárová

Slovenská poľnohospodárska univerzita, Katedra fyziky, Tr. A. Hlinku 2, SK-94976 Nitra,

Slovak Republic

Transport processes in biological materials and their simplified mathematical description are briefly surveyed. The effect of material on transport processes is expressed by corresponding transport quantities. The influence of some factors, namely of the temperature and the moisture on transport processes in biological materials is discussed.