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The development of high performance insulating materials incorporating nanotechnologies has enabled considerable decrease in the effective thermal conductivity. Besides the use of conventional insulating materials, such as mineral fibers, the adoption of new nano-technological materials such as aerogel, vacuum insulation panels, graphite expanded polystyrene, is growing. In order to reduce the thermal conductivity of polystyrene insulation materials, during the manufacturing, nano/micro-sized graphite particles are added to the melt of the polystyrene grains. The mixing of graphite flakes into the polystyrene mould further reduces the lambda value, since graphite parts significantly reflect the radiant part of the thermal energy. In this study, laboratory tests carried out on graphite insulation materials are presented. Firstly, thermal conductivity results are described, and then sorption kinetic curves at high moisture content levels are shown. The moisture up-taking behaviour of the materials was investigated with a climatic chamber where the relative humidity was 90% at 293 K temperature. Finally, calorific values of the samples are presented after combusting in a bomb calorimeter.

Open access

The European corn borer moth, (ECB), Ostrinia nubilalis (Lepidoptera: Crambidae, Pyraustinae) is one of the most destructive pests of maize worldwide. ECB has two pheromone-strains, separated by specific ratios of isomers of E- and Z11-tetradecenyl acetates (E11- and Z11-14Ac), but appearing morphologically identical. Accordingly, E- and Z-ECB pheromone traps are available for the respective populations for practical monitoring of the flight, however, traps for Z-strain are unreliable for practical usage in some parts of Central-Europe. E- and Z-ECB populations occur in sympatry in some areas, while in allelopatry in other areas. Determining the strains before the flight of adults, when difference in the composition of their respective pheromones is manifested, would be of practical interest for early warning. In addition to the known fatty-acyl-reductase (FAR) marker, further markers would allow more comprehensive studies. We screened the following common markers for mitochondrial and nuclear DNA regions: partial cytochrome c oxidase I (COI), cytochrome B (CytB), the second spacer of the internal transcribed spacer (ITS2), Elongation factor 1a (EF1a) and actin gene (Act). In addition, a marker of the Δ11-desaturase gene (11desat), linked to biosynthesis of female-produced sex pheromone, was also included, because we reported earlier a differential expression for this site. Three Z-ECB populations locating at distant sites within Hungary, an area where only Z-strain occurs, and an E-ECB population in Slovenia, known as the closest-occurring E-strain, were included into the study. Separate laboratory colonies were established from each population, and F1 generations were sampled to verify the identity of pheromone strains, by analysing the composition of sex pheromone by gas chromatography linked to an electroantennographic detector (GC-EAD). Molecular studies were conducted using specimens taken from the F2 generations. Results of genetic studies showed that there were no differences between the Z and E populations for the common markers. In contrast to this, several nucleic acid changes (11 nt in 4 positions) were found between the three Z-populations (Hungary) and the E-population (Slovenia) in the desaturase marker. Further study is required to reveal whether the differences found in this study are consistent across E-populations, thus making these markers suitable for diagnostic purposes.

Open access

The laboratory investigations of the heat transfer properties of wall structures are very significant from the point of view of designing the buildings. In this article measurements and calculations will be presented in order to manifest the effect of the forced and un-forced convection of air at the cold surface of the wall. A steady-state method for measuring the thermal resistance of wall structures with Hukseflux apparatus is presented in this article. The measurements were accomplished through, firstly on an un-insulated inbuilt plaster/brick/plaster wall construction and later it was covered with a 0.013 m thick aerogel layer blanket. Aerogels are nanoporous lightweight materials, were discovered more than 70 years ago. In these years their applications are truly spread over. During the investigations the wall structures were tested without forcing the air to motion, and then measurements were carried both on the insulated and un-insulated wall structures, where the movement of the air was forced by a ventilator from three different directions with the same 1 m/s velocity near the wall.

Open access
Acta Alimentaria
Authors: P. Olejníková, A. Kaszonyi, M. Šimkovič, B. Lakatoš, M. Kaliňák, M. Valachovičová, and L. Birošová

The human endogenous intestinal microbiota is an essential “organ” in providing nourishment, regulating epithelial development, and instructing innate immunity. Even though lots of scientists have evaluated the content of gut microbiota from various points of view, we examined the content of intestinal microbes in the group of healthy middle aged volunteers (40–60) form Slovakia. We have compared faecal cultivable microbiota of vegetarians and omnivores. We have found that the composition of the human microbiota is fairly stable, and it seems that the major microbial groups on species level that dominate the human intestine are conserved in all individuals regardless of dietary habits. Beside the microbial content we have examined the faecal samples also for the presence of antimicrobial active compounds, potential mutagens, and faecal sterols.

Open access

Abstract

Objective

In this observational study we addressed accelerated arteriosclerosis (AS) in patients with chronic renal failure (CRF) on hemodialysis (HD) by measuring vascular stiffness (VS) parameters and attempted to relate them to pro-inflammatory and protective factors.

Patients

96 consecutive patients receiving regular HD were included. 20 adult patients without major renal, cardiovascular or metabolic morbidities served as controls.

Methods

AS parameters (carotid-femoral pulse wave velocity – PWV, aortic augmentation index – Aix) were measured by using applanation tonometry (SphygmoCor, AtCor Medical, Sidney). In addition to routine laboratory tests 25(OH) vitamin D3 (vitamin D3) and high-sensitivity C-reactive protein (hsCRP) were quantified by immunometric assay; whereas fetuin-A, α-Klotho, tumor necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β1) were determined by ELISA.

Results

Pro-inflammatory biomarkers (hsCRP, TNF-α and TGF-β1) were markedly elevated (P < 0.01), while anti-inflammatory factors (fetuin-A: P < 0.05, α-Klotho: P < 0.01, vitamin D3: P < 0.01) significantly depressed in HD patients when compared to controls. PWV was significantly affected only by total cholesterol, fetuin-A and dialysis time. Multiple linear regression analyses revealed that several clinical and laboratory parameters were associated with pro- and anti-inflammatory biomarkers rather than VS. The impact of baseline clinical and biochemical variables on outcome measures were also analyzed after three-year follow-up, and it was demonstrated that low levels of vitamin D, α-Klotho protein and fetuin-A were related to adverse cardiovascular outcomes, whereas all-cause mortality was associated with elevated hsCRP and depressed vitamin D.

Conclusions

Our results provide additional information on the pathomechanism of accelerated AS in patients with CRF, and documented direct influence of pro- and anti-inflammatory biomarkers on major outcome measures.

Open access