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Start Over Subject temperature dependence

1. An unusual temperature dependence of malondialdehyde formation in Fe2+/H2O2-initiated lipid peroxidation of phosphatidylcholine liposomes

Creator:
Mišík, V., Gergeľ, D., Alov, P., and Ondriaš, K.
Type:
article, model:article, and TEXT
Subject:
lipid peroxidation, malondialdehyde, temperature dependence, and oxygen consumption
Language:
English
Description:
Determination of malondialdehyde is a widely used procedure for measurement of lipid peroxidation. In this paper we report an unusual temperature dependence of malondialdehyde formation in egg yolk phosphatidylcholine liposomes oxidized by the Fenton system (0.1 mmol/1 FeSC>4 and 0.05 mmol/1 H2O2). The amount of malondialdehyde formed was 37 % higher in samples kept at 22 °C than at 50 °C. An alternative method for determination of lipid peroxidation, measurement of oxygen uptake, revealed complete consumption of dissolved oxygen to peroxidized lipids at 22 °C as well as 50 °C. Since oxygen is essential for the formation of cyclic peroxides - precursors of malondialdehyde - we conclude that the nature of the observed effect consists in limitation of oxygen availability at elevated temperatures.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2. Teplotní závislosti spektrálních a laserových vlastností aktivního prostředí Cr:ZnSe

Creator:
Říha, Adam, Jelínková, Helena, Němec, Michal, Vyhlídal, David, Čech, Miroslav, Doroshenko, Maxim E., and Badikov, Valerij V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
active medium, Cr:ZnSe laser, temperature dependence, fluorescence, mid-infrared spectral range, aktivní prostředí, teplotní závislost, and střední infračervená oblast
Language:
Czech
Description:
The interest in developing coherent mid-infrared radiation sources is caused due to their potential use in medicine, spectroscopy, laser remote sensing of the atmosphere, metrology, and in many other fields of interest. One of possible sources of such radiation may be Cr:ZnSe laser. Therefore, this study presents new results of Cr:ZnSe active medium temperature dependence in range 78-380 K of spectral and laser properties. The influence of temperature on absorption, fluorescence and oscillation spectra were investigated in detail. Upon heating the Cr:ZnSe crystal from 78 K to 380 K, the absorption peak maximum has shifted by 65 nm towards shorter wavelengths from 1813 nm to 1748 nm. From the point of view of the generation of Cr:ZnSe laser radiation, the temperature dependence of Cr:ZnSe laser radiation energy and oscillation spectra were studied. The generated laser radiation spectrum was for different temperatures observed in three wavelength bands around 2290, 2360, and 2445 nm. The highest output energy of 3.84 mJ was reached at temperature 78 K. and Zájem o vývoj koherentních zdrojů infračerveného záření je dán jejich potenciálním využitím v medicíně, spektroskopii, laserovém dálkovém snímání atmosféry, metrologii a v mnoha dalších oblastech. Jedním ze zdrojů takového záření může být i Cr:ZnSe laser. Tato studie představuje nové výsledky měření teplotních závislostí spektrálních a laserových vlastností aktivního prostředí Cr:ZnSe v teplotním rozsahu 78-380 K. Podrobně byl zkoumán vliv teploty na absorpční, fluorescenční a oscilační spektra. Při zahřívání krystalu Cr:ZnSe ze 78 K na 380 K se maximum absorpce posunulo o 65 nm směrem ke kratším vlnovým délkám z 1813 nm na 1748 nm. Z hlediska generace laserového záření Cr:ZnSe byla studována teplotní závislost výstupní energie Cr:ZnSe laseru a oscilačních spekter. Generované spektrum laserového záření bylo pro různé teploty pozorováno ve třech pásmech vlnových délek v okolí 2290, 2360 a 2445 nm. Nejvyšší výstupní energie 3,84 mJ byla dosažena při teplotě 78 K.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

3. Water infiltration in an aquifer recharge basin affected by temperature and air entrapment

Creator:
Loizeau, Sébastien, Rossier, Yvan, Gaudet, Jean-Paul, Refloch, Aurore, Besnard, Katia, Angulo-Jaramillo, Rafael, and Lassabatere, Laurent
Type:
article, model:article, and TEXT
Subject:
aquifer recharge, unsaturated/saturated modeling, infiltration test, air entrapment, and temperature dependence
Language:
Slovak
Description:
Artificial basins are used to recharge groundwater and protect water pumping fields. In these basins, infiltration rates are monitored to detect any decrease in water infiltration in relation with clogging. However, miss-estimations of infiltration rate may result from neglecting the effects of water temperature change and air-entrapment. This study aims to investigate the effect of temperature and air entrapment on water infiltration at the basin scale by conducting successive infiltration cycles in an experimental basin of 11869 m2 in a pumping field at Crepieux-Charmy (Lyon, France). A first experiment, conducted in summer 2011, showed a strong increase in infiltration rate; which was linked to a potential increase in ground water temperature or a potential dissolution of air entrapped at the beginning of the infiltration. A second experiment was conducted in summer, to inject cold water instead of warm water, and also revealed an increase in infiltration rate. This increase was linked to air dissolution in the soil. A final experiment was conducted in spring with no temperature contrast and no entrapped air (soil initially water-saturated), revealing a constant infiltration rate. Modeling and analysis of experiments revealed that air entrapment and cold water temperature in the soil could substantially reduce infiltration rate over the first infiltration cycles, with respective effects of similar magnitude. Clearly, both water temperature change and air entrapment must be considered for an accurate assessment of the infiltration rate in basins.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public