Fire Resistance Increase of Structural Steel through the Modification of its Chemical Composition

AbstractIn the article the possibility for increasing the fire resistance of structural steel used in building load-bearing structures is presented and discussed in detail. The recommended approach is based on a suitable modification of its chemical composition, in particular by adding the carefully selected alloying elements. With such a change, not only a high-temperature strength of this material may be significantly increased in relation to that which would be achieved for the typical structural steel with an unmodified composition but also its sufficient weldability should be ensured by the entire duration of its exposure to a fire. The steel modified in this way would be undoubtedly more expensive to manufacture but due to the fact that it will not require any special protection against fire it seems that it can provide an interesting alternative to the solutions currently used in engineering practice

Soil research in the Eastern Carpathians and its significance in the protection of soils of the Bieszczady National Park

The first pedological research in the Eastern Carpathians was carried out in Chornokhora and Czywczynskie Mountains in the 1930s. After 1945 and the border change detailed soil research was undertaken in the Western Bieszczady Mts. situated in Poland. A soil map of the Bieszczady National Park was prepared in the 1:10 000 scale, also a number of papers concerning soil cover properties and its protection were published. In the 1990s in the area of Chornokhora, in cooperation with the scientists from Kraków (Poland) and Lwów and Chernivtsi (Ukraine), a soil research was carried out. Results of this research form a basis for the guidelines for the protection plans of Bieszczady and Chornokhora Mountains environment

Synergistic ROS-Associated antimicrobial activity of silver nanoparticles and gentamicin against "Staphylococcus epidermidis"

Introduction: Increasing bacteria resistance to antibiotics is a major problem of healthcare system. There is a need for solutions that broaden the spectrum of bactericidal agents improving the efficacy of commonly used antibiotics. One of the promising directions of search are silver nanoparticles (obtained by different methods and displaying diversified physical and chemical properties), and their combination with antibiotics. Purpose: In this study, we tested the role of reactive oxygen species in the mechanism of synergistic antibacterial activity of gentamicin and Tween-stabilized silver nanoparticles against gentamicin-resistant clinical strains of Staphylococcus epidermidis. Methods: Synergistic bactericidal activity of gentamicin and silver nanoparticles stabilized with non-ionic detergent (Tween 80) was tested by the checkerboard titration method on microtiter plates. Detection of reactive oxygen species was based on the chemiluminescence of luminol. Results: Hydrophilic non-ionic surface functionalization of silver nanoparticles enabled the existence of non-aggregated active nanoparticles in a complex bacterial culture medium. Tween-stabilized silver nanoparticles in combination with gentamicin exhibited bactericidal activity against multidrug-resistant biofilm forming clinical strains of Staphylococcus epidermidis. A synergistic effect significantly decreased the minimal inhibitory concentration of gentamicin (the antibiotic with numerous undesirable effects). Gentamicin significantly enhanced the generation of reactive oxygen species by silver nanoparticles. Conclusion: Generation of reactive oxygen species by Tween-coated metallic silver nanoparticles was significantly enhanced by gentamicin, confirming the hypothesis of oxidative-associated mechanism of the synergistic antibacterial effect of the gentamicin-silver nanoparticles complex

Radionuclides ^{137}Cs and ^{40}K in the soils of the Tatra National Park (TPN, Poland)

The paper presents the results of radioactivity determination of artificial 137Cs and natural 40K in soil samples taken from the Tatra Mountains in Poland (Tatra National Park – TPN). Soil samples were collected as the cores of 10 cm in diameter and 10 cm in depth. These cores were divided into 3 slices. It has been found that the content of 137Cs was the highest at the sites of the altitude over 1300 m a.s.l. The values of 137Cs concentration in the soils examined varied – from 55.8 Bqźkg–1 (dry mass) (417.8 Bqźm–2) for the Tomanowa Pass (1685 m a.s.l.) to 5111 Bqźkg–1 (dry mass) (8400 Bqźm–2) for the Krzyzne Pass (2112 m a.s.l.). In most cases, the values were lower than the average radiocaesium concentration established for Poland

Lithic Leptosols in the subalpine and alpine meadows (poloninas) in the Bieszczady Mts and Chornokhora Mts (Eastern Carpathians)

Characteristics of the Bieszczady Mts. and Chornokhora Mts. soils at the primary stadium of development (Lithic Leptosols) has been described. These soils are very shallow formations with profile consisting of a few centimetre of 0fh mor/moder type organic matter horizon situated directly on the weathered rock (R) or on the thick-grained regolith. The organic matter is in the primary stadium of humification, its reaction is very acidic (pH 3,5-4,0) and the fulvic acids prevail within the humus substance fractions. In some cases ratio 1:1 between fulvic and humic acids can be observed

Role of chemokine RANTES in the regulation of perivascular inflammation, T-cell accumulation, and vascular dysfunction in hypertension

Recent studies have emphasized the role of perivascular inflammation in cardiovascular disease. We studied mechanisms of perivascular leukocyte infiltration in angiotensin II (Ang II)-induced hypertension and their links to vascular dysfunction. Chronic Ang II infusion in mice increased immune cell content of T cells (255 ± 130 to 1664 ± 349 cells/mg; P < 0.01), M1 and M2 macrophages, and dendritic cells in perivascular adipose tissue. In particular, the content of T lymphocytes bearing CC chemokine receptor (CCR) 1, CCR3, and CCR5 receptors for RANTES chemokine was increased by Ang II (CCR1, 15.6 ± 1.5% vs. 31 ± 5%; P < 0.01). Hypertension was associated with an increase in perivascular adipose tissue expression of the chemokine RANTES (relative quantification, 1.2 ± 0.2 vs. 3.5 ± 1.1; P < 0.05), which induced T-cell chemotaxis and vascular accumulation of T cells expressing the chemokine receptors CCR1, CCR3, and CCR5. Mechanistically, RANTES−/− knockout protected against vascular leukocyte, and in particular T lymphocyte infiltration (26 ± 5% in wild type Ang II vs. 15 ± 4% in RANTES−/−), which was associated with protection from endothelial dysfunction induced by Ang II. This effect was linked with diminished infiltration of IFN-γ-producing CD8+ and double-negative CD3+CD4−CD8− T cells in perivascular space and reduced vascular oxidative stress while FoxP3+ T-regulatory cells were unaltered. IFN-γ ex vivo caused significant endothelial dysfunction, which was reduced by superoxide anion scavenging. In a human cohort, a significant inverse correlation was observed between circulating RANTES levels as a biomarker and vascular function measured as flow-mediated dilatation (R = −0.3, P < 0.01) or endothelial injury marker von Willebrand factor (R = +0.3; P < 0.01). Thus, chemokine RANTES is important in the regulation of vascular dysfunction through modulation of perivascular inflammation.—Mikolajczyk, T. P., Nosalski, R., Szczepaniak, P., Budzyn, K., Osmenda, G., Skiba, D., Sagan, A., Wu, J., Vinh, A., Marvar, P. J., Guzik, B., Podolec, J., Drummond, G., Lob, H. E., Harrison, D. G., Guzik, T. J. Role of chemokine RANTES in the regulation of perivascular inflammation, T-cell accumulation, and vascular dysfunction in hypertension

1,2,3,4,6 penta-O -galloyl-β-D-glucose modulates perivascular inflammation and prevents vascular dysfunction in angiotensin II-induced hypertension

Background and Purpose: Hypertension is a multifactorial disease, manifested by vascular dysfunction, increased superoxide production and perivascular inflammation. In this study, we have hypothesized that 1,2,3,4,6 Penta‐O‐Galloyl‐β‐D‐Glucose (PGG) would inhibit vascular inflammation and protect from vascular dysfunction in an experimental model of hypertension. Experimental Approach: PGG was administered every two days in a dose of 10 mg·kg‐1 i.p during 14‐days of Ang II infusion and was used in a final concentration of 20 μM for in vitro studies. Key Results: Ang II administration increased leukocyte and T cell content in perivascular adipose tissue (pVAT) and administration of PGG significantly decreased total leukocyte and T cell infiltration in pVAT (1640±150 vs. 1028±57, p<0.01; 321±22 vs 158±18, cells/mg; p<0.01, respectively). This effect was observed in relation to all T cell subsets. PGG also decreased the content of T cells bearing CD25, CCR5 and CD44 receptors and the expression of both MCP‐1 in aorta and RANTES in pVAT. PGG administration decreased the content of TNF+ and IFN‐γ+ CD8 T cells and IL‐17A+ CD4+ and CD3+CD4‐CD8‐ cells. Importantly, these effects of PGG were associated with improved vascular function and decreased ROS production in the aortas of Ang II‐infused animals independently of blood pressure increase. Mechanistically, PGG (20 μM) directly inhibited CD25 and CCR5 expression in cultured T cells. It also decreased the content of IFN‐γ+ by CD8+ and CD3+CD4‐CD8‐ cells and IL‐17A+ by CD3+CD4‐CD8‐ cells. Conclusion and Implication: PGG may constitute an interesting immunomodulating strategy in the regulation of vascular dysfunction and hypertension