Operation of railway vehicles at higher speeds is conditioned by assurance of a stable run of the vehicle in straight track with a high level of geometric parameters. This property is usually reached by retrofitting of a joint between the vehicle body and the bogies with an efficient damping with suitable characteristics. As the relative motion between the vehicle body and the bogies in the straight track shows low amplitudes and high velocities, special longitudinal dampers - so-called yaw dampers - are used for these purposes. The aim of this paper is a theoretical analysis of influence of yaw dampers characteristics on the stability limit of a locomotive performed by means of sensitivity analysis. and Obsahuje seznam literatury
Osteoporosis is a bone disease characterized by low bone mineral density (BMD) and impaired bone microarchitecture due to the abnormal activity of osteoclasts. Cathelicidins are antimicrobial peptides present in the lysosomes of macrophages and polymorphonuclear leukocytes. LL-37, a cathelicidin, induces various biological effects, including modulation of the immune system, angiogenesis, wound healing, cancer growth, as well as inflammation, and bone loss. A previous study reported direct involvement of LL-37 suppressing osteoclastogenesis in humans. Here, we examined the role of LL-37 in the treatment of osteoporosis using an ovariectomy (OVX) rat model. Our results showed that LL-37 significantly reduced bone loss and pathological injury in OVX rats with osteoporosis. Furthermore, we found that LL-37 significantly increased the activity of the Wnt/β-catenin pathway in OVX rats with osteoporosis, including the increased expression of β-catenin, Osterix (Osx), and Runt-related transcription factor 2 (Runx2), whereas XAV-939, an inhibitor of the Wnt/β-catenin pathway, significantly blocked the effects of LL-37 on bone loss and abnormal bone metabolism. Altogether, our findings suggested that LL-37 exerted a protective role in regulating bone loss and abnormal bone metabolism in rats with osteoporosis by activating the Wnt/β-catenin pathway.
Nitrogen is an essential factor for normal plant and algal development. As a component of nucleic acids, proteins, and chlorophyll (Chl) molecules, it has a crucial role in the organization of a functioning photosynthetic apparatus. Our aim was to study the effects of nitrogen starvation in cultures of the unicellular green alga, Chlamydomonas reinhardtii, maintained on nitrogen-free, and then on nitrogen-containing medium. During the three-week-long degreening process, considerable changes were observed in the Chl content, the ratio of Chl-protein complexes, and photosynthetic activity of the cultures as well as in the ultrastructure of single chloroplasts. The regreening process was much faster then the degradation; total greening of the cells occurred within four days. The rate of regeneration depended on the nitrogen content. At least 50% of the normal nitrogen content of Tris-Acetate-Phosphate (TAP) medium was required in the medium for the complete regreening of the cells and regeneration of chloroplasts., É. Preininger, A. Kósa, Z. S. Lőrincz, P. Nyitrai, J. Simon, B. Böddi, Á. Keresztes, I. Gyurján., and Obsahuje seznam literatury
Biocrusts are biological communities that occupy the soil surface, accumulate organic matter and mineral particles and hence strongly affect the properties of the soils they cover. Moreover, by affecting water repellency, biocrusts may cause a preferential infiltration of rainwater, with a high impact on the formation of local water pathways, especially for sand dunes. The aim of this study is to shed light on the connections between water repellency and pH, carbonate and organic matter content in two dune ecosystems with different biocrust types. For this, we used contact angle measurements, gas volumetric carbonate determination and organic matter characterization via FT-IR and TOFSIMS. In both ecosystems, moss-dominated biocrusts showed higher water repellency and higher amounts of organic matter compared to algal or cyanobacterial biocrusts. Surprisingly, the biocrusts of the two dune systems did not show differences in organic matter composition or organic coatings of the mineral grains. Biocrusts on the more acidic dunes showed a significantly higher level of water repellency as compared to higher carbonate containing dunes. We conclude that the driving factor for the increase in water repellency between cyanobacterial and moss-dominated biocrusts within one study site is the content of organic matter. However, when comparing the different study sites, we found that higher amounts of carbonate reduced biocrust water repellency.