High temperature alters the internal microstructure of rocks and consequently changes the physical and mechanical properties of rocks. Many studies have been carried out to examine the transformations in the microstructures of rocks under high temperature through near infrared spectroscopy (NIR), Raman spectroscopy, or thermo gravimetric analysis (TGA). The current review synthesizes the data from a number of literatures and summarizes the major transformations of silica rocks under high temperature. The analysis shows that silica rocks starts to lose the water adsorbed in open pores upon heating at about 150 °C. At 200-300 °C, the reaction between SiOH (silanole) in the rocks generates new Si-O-Si bonds as well as H2O, and decreases the open pores. The rocks undergo volume expansion at >550 °C, and the volume contracts and forms new micro pores or cracks which play an important role in the evacuation of the water., Jishi Geng, Qiang Sun, Yuchun Zhang and Yuliang Zhang., and Obsahuje bibliografické odkazy
The acclimation to high light, elevated temperature, and combination of both factors was evaluated in tomato (Solanum lycopersicum cv. M82) by determination of photochemical activities of PSI and PSII and by analyzing 77 K fluorescence of isolated thylakoid membranes. Developed plants were exposed for six days to different combinations of temperature and light intensity followed by five days of a recovery period. Photochemical activities of both photosystems showed different sensitivity towards the heat treatment in dependence on light intensity. Elevated temperature exhibited more negative impact on PSII activity, while PSI was slightly stimulated. Analysis of 77 K fluorescence emission and excitation spectra showed alterations in the energy distribution between both photosystems indicating alterations in light-harvesting complexes. Light intensity affected the antenna complexes of both photosystems stronger than temperature. Our results demonstrated that simultaneous action of high-light intensity and high temperature promoted the acclimation of tomato plants regarding the activity of both photosystems in thylakoid membranes., A. Faik, A. V. Popova, M. Velitchkova., and Obsahuje bibliografii
V roku 1948 holandský fyzik H. B. G. Casimir navrhol špeciálne experimentálne zariadenie, ktoré spočívalo v dvojici rovnobežných vodivých platní, pričom každá z platní bola elektricky neutrálna. Casimir vypočítal, že zmena vákuovej energie elektromagnetického poĺa spôsobená prítomnosťou platní se prejavuje ako makroskopická príťažlivá sila medzi platňami. Ďalšie štúdie zovšeobecnili, v rámci štandardnej rovnovážnej štatistickej a kvantovej mechaniky aplikovanej na makroskopickú elektrodynamiku, odvodenie príťažlivej Casimirovej sily na nenulovú teplotu T > 0, prípad všeobecných platní vyrobených z dielektrického materiálu a rôzné geometrie experimentálnych zariadení. Časom sa ukázalo, že v dosiahnutých výsledkoch je nesúlad a množstvo kontroverzií. Nesúlad výsledkov sa najmarkantnejšie prejavuje v oblasti vysokých teplôt. Cieĺom prezentovaného článku je poskytnúť stručný prehĺad vývoja Casimirovho problému a jeho kontroverzií v matematicky prístupnej forme, ako aj autorov príspevok pri objasnení vysokoteplotných aspektov elektromagnetického Casimirovho javu., Ladislav Šamaj., and Obsahuje seznam literatury
Permeability plays an important role in the field of geotechnical engineering. Under high temperature and high pressure condition, the physical-chemical and structure properties (such as decomposition, oxidation, dehydration, evaporation, phase transition etc.) of rock have obviously changing, which are significant affected the rock permeability. In order to analyze the influence of temperature and confining pressure on the permeability of rock (sandstones, siltstones and conglomerates) data for permeability was obtained from the literature. The results indicate that temperature and confining pressure have great influence on the permeability of rock, especially for sandstone. There is a threshold temperature and when the heating temperature is lower than the threshold temperature, the permeability of sandstone gradually increases with an increase in temperature. When the heating temperature is higher than 300 ºC (especially 400 ºC), the permeability rapidly increases. The permeability of sandstone decreases gradually with the confining pressure increases. This study of the relationship between rock permeability and temperature and confining pressure lays a foundation for investigations of multi-disciplinary issues regarding high temperatures and high pressures and it can be used for the study of petroleum storage and safe nuclear waste disposal., Zhenlong Ge, Qiang Sun and Wenping Li., and Obsahuje bibliografii