The Effect of Elevated Temperature on Ordinary Portland Cements

A study was directed to analyze the influence of the different types of Ordinary Portland Cements (OPC) on the hardened cement paste exposed to high temperatures. Hardened cement paste specimens with three types of cement and nine water-cement ratios were investigated and heated to 11 heat steps at 28 days of age. Residual compressive strength and relative residual compressive strength were compared to the unheated results. It was shown that the expected range for the relative residual strength of the different types of OPC up to 400 °C is between 90 and 100%. From the local minimum at 150 °C to the maximum at 300 °C. The CEM I 52.5 type of cement shows the least favorable behavior to the increased (over 400 °C) temperature, according to the results of the residual compressive strengths curves and the newly introduced Integrated Temperature Endurance values after the first water-cement ratio (0.3). Nine water-cement ratios were tested with the favorable types of OPC (CEM I 42.5 and CEM I 32.5). At all water-cement ratios, the residual strength tendencies for the two types of cement were parallel. It has been observed that changes in the water-cement ratio have little to no impact on the relative strength curve's shape or the relationship between strength and the water cement ratio. As a result of our experiments applying simply Ordinary Portland Cement, it is obvious that the CEM I 32.5 type of OPC cement significantly outperformed the CEM I 42.5 type in regards of post-heating strength tendencies

Effect of the concrete´s component on the heat shock bearing capacity of tunnel linings

During the last decades, the increasing number of incidents in road and railway tunnels have attracted public attention to the danger of tunnel fires. These incidents established that quickly accumulating, huge amount of evolved heat impairs the reinforced concrete structures of tunnel linings. Designing of fire-bearing linings, it is necessary to understand the behaviour of the linings impacted by bumping heat load. In this paper, the results of our heat load examinations of residual strength (compressive strength and split-tensile strength) parameters on different mixtures of concrete were summarised

Effect of plant density on grain yield, yield components and agronomic traits of maize (Zea mays L.) hybrids

KAL

The relationship of louse infestation and clutch size in the Common Kestrel (Falco tinnunculus)

SUMMARY Background: Lice are common ectoparasites of birds, completing their entire life cycle in the plumage. Transmission – in most cases – requires physical contact between hosts. Lice may benefit from choosing host individuals with better survival prospects and dispersal chances. Bodily contacts between parents and offsprings provide a good opportunity for host selection. The Common Kestrel is a widespread, small-bodied raptor of the Palearctic region, with well-known breeding biology and ectoparasite fauna, making it suitable to study the ecological correlates of vertical transmission of lice. Objectives: The aim of our study was to investigate how the sex, maturity and clutch size of Common Kestrel nestlings affect the abundance of their lice. Materials and Methods: Field work was carried out in Körös-Maros National Park Directorate (Hungary). The ectoparasites were collected from nestlings (n = 54) with dust-ruffling. The effect of the host’s sex, wing length and clutch size on the abundance of their lice was analysed using negative binomial mixed models. Results and Discussion: In case of Colpocephalum subzerafae, none of the investigated variables had a significant effect. Contrarily, clutch size had a significant effect on Degeeriella rufa abundance. In small clutches (3–4 nestlings) the mean abundance of D. rufa (15.5 95% C.I.: 8–30) is 3.7 times higher, than in large (5–6 nestlings) clutches (4.2 95% C.I.: 2.3–7.4). We discuss two non-exclusive explanations of this pattern. First, parental quality is known to affect the clutch size. If low quality parents are also more heavily infested with lice, this could explain the higher louse load of their nestlings. Alternatively, according to the dilution hypothesis, long life-cycle ectoparasites (such as lice), that are incapable to significantly raise their subpopulation size till the fledging of the chicks, disperse among the nestlings, resulting in lower per nestling louse counts in larger clutches. According to our results both the breeding parameters and the quality of the parents may affect their offsprings’ ectoparasite load

Direct Oral Anticoagulants as the First Choice of Anticoagulation for Patients with Peripheral Artery Disease to Prevent Adverse Vascular Events: A Systematic Review and Meta-Analysis

The best method of anticoagulation for patients with peripheral artery disease (PAD) is still a topic of interest for physicians. We conducted a meta-analysis to compare the effects of direct oral anticoagulants (DOACs) with those of vitamin-K-antagonist (VKA) anticoagulants in patients with peripheral artery disease. Five databases (Medline (via PubMed), EMBASE, Scopus, Web of Science, and CENTRAL) were searched systematically for studies comparing the effects of the two types of anticoagulants in patients with PAD, with an emphasis on lower-limb outcomes, cardiovascular events, and mortality. In PAD patients with concomitant non-valvular atrial fibrillation (NVAF), the use of DOACs significantly reduced the risk of major adverse limb events (HR = 0.58, 95% CI, 0.39–0.86, p p p p = 0.2) and cardiovascular mortality (HR = 0.77, 95% CI, 0.58–1.02, p = 0.07). Rivaroxaban at higher doses significantly increased the risk of major bleeding (HR = 1.16, 95% CI, 1.07–1.25, p p = 0.14) in PAD patients in whom a poor distal runoff was the reason for the anticoagulation. DOACs have lower rates of major limb events, stroke, and mortality than VKAs in PAD patients with atrial fibrillation. Rivaroxaban at higher doses increased the risk of major bleeding compared with other DOAC drugs. More high-quality studies are needed to determine the most appropriate anticoagulation regimen for patients with lower-limb atherosclerosis