To investigate damaging mechanisms of chilling and salt stress to peanut (Arachis hypogaea L.) leaves, LuHua 14 was used in the present work upon exposure to chilling temperature (4°C) accompanied by high irradiance (1,200 μmol m-2 s-1) (CH), salt stress accompanied by high irradiance (1,200 μmol m-2 s-1) (SH), and high-irradiance stress (1,200 μmol m-2 s-1) at room temperature (25°C) (NH), respectively. Additionally, plants under low irradiance (100 μmol m-2 s-1) at room temperature (25°C) were used as control plants (CK). Relative to CK and NH treatments, both the maximal photochemical efficiency of PSII (Fv/Fm) and the absorbance at 820 nm decreased greatly in peanut leaves under CH and SH stress, which indicated that severe photoinhibition occurred in peanut leaves under such conditions. Initial fluorescence (F0), 1 - qP and nonphotochemical quenching (NPQ) in peanut leaves significantly increased under CH- and SH stress. Additionally, the activity of superoxide dismutase (SOD), one of the key enzymes of water-water cycle, decreased greatly, the accumulation of malondialdehyde (MDA) and membrane permeability increased. These results suggested that damages to peanut photosystems might be related to the accumulation of reactive oxygen species (ROS) induced by excess energy, and the water-water cycle could not dissipate energy efficiently under the stress of CH and SH, which caused the accumulation of ROS greatly. CH and SH had similar damaging effects on peanut photosystems, except that CH has more severe effects. All the results showed that CH- and SH stress has similar damaging site and mechanisms in peanut leaves. and L.-Q. Qin ... [et al.].
Tree hyraxes - genus Dendrohyrax - are among the least known mammals. in this review we summarize all known facts on their ecology and ethology. According to the Zoological Information Management System the only two zoos worldwide currently holding these animals are found in the Czech Republic. Therefore, also the information on their husbandry is included. and Jan Pluháček, Yveta Svobodová.
Golden age of damascus steel has passed away, however his value still remains. It could be even said that this material passes through his renaissance in the last years. Besides aesthetic properties it has doubtless very interesting mechanical properties. For example, strength of final material is higher than strength of his particular components, whereas hardness is relatively low - as is apparent from done experiment. and Zlatá éra damascenské oceli sice již dávno minula, avšak její hodnota stále přetrvává. Dokonce lze říci, že v posledních letech zažívá tento materiál svou renesanci. Vedle estetických vlastností jsou nesporně zajímavé i jeho vlastnosti mechanické. Zkoušky provedené na vzorku svářkového damašku například ukázaly, že pevnost výsledného materiálu je mnohem vyšší než pevnost jeho dílčích složek, přičemž tvrdost zůstává relativně nízká.