Utjecaj vodika u krutoj otopini čelika za opruge

This paper is concerned with the question of the brittle cracking of spring steel, which can occur already in the early stages of steel processing, i.e. during rolling, during the mechanical cutting of rolled profiles, or during any other type of mechanical manipulation where the harmful effect of remaining hydrogen has been observed. In order to investigate this question in greater depth, mechanical tests and fractographic analyses of the fracture surfaces were performed on cathodically hydrogenated test specimens of two types of spring steel, with and without alloyed nitrogen, in order to determine the critical concentration of hydrogen below which a relatively ductile fracture surface occurs, with good resistance to brittle cracking, and above which hydrogen embrittlement occurs.Ovaj rad odnosi se na problematiku krtog pucanja čelika za opruge već u njegovoj ranoj fazi prerade: pri valjanju, strojnom rezanju valjanih profila, ili kod neke druge mehaničke obrade, gdje je bio uočen škodljiv utjecaj zaostalog vodika. Pomoću uzoraka koji su bili katodno vodičeni, mehaničkog ispitivanja tih uzoraka i fraktografske analize prelomnih površina, bila je definirana kritična količina vodika. Ispod te kritične količine prisutna je još relativno žilava prelomna površina i dobra otpornost prema krhkom pucanju radi vodikove krhkosti. Iznad te vrijednosti, manifestira se vodikova krhkost

Sex- and age-related differences in the management and outcomes of chronic heart failure: an analysis of patients from the ESC HFA EORP Heart Failure Long-Term Registry

Aims: This study aimed to assess age- and sex-related differences in management and 1-year risk for all-cause mortality and hospitalization in chronic heart failure (HF) patients. Methods and results: Of 16 354 patients included in the European Society of Cardiology Heart Failure Long-Term Registry, 9428 chronic HF patients were analysed [median age: 66 years; 28.5% women; mean left ventricular ejection fraction (LVEF) 37%]. Rates of use of guideline-directed medical therapy (GDMT) were high (angiotensin-converting enzyme inhibitors/angiotensin receptor blockers, beta-blockers and mineralocorticoid receptor antagonists: 85.7%, 88.7% and 58.8%, respectively). Crude GDMT utilization rates were lower in women than in men (all differences: P\ua0 64 0.001), and GDMT use became lower with ageing in both sexes, at baseline and at 1-year follow-up. Sex was not an independent predictor of GDMT prescription; however, age >75 years was a significant predictor of GDMT underutilization. Rates of all-cause mortality were lower in women than in men (7.1% vs. 8.7%; P\ua0=\ua00.015), as were rates of all-cause hospitalization (21.9% vs. 27.3%; P\ua075 years. Conclusions: There was a decline in GDMT use with advanced age in both sexes. Sex was not an independent predictor of GDMT or adverse outcomes. However, age >75 years independently predicted lower GDMT use and higher all-cause mortality in patients with LVEF 6445%

Expression of human telomerase catalytic protein in gallbladder carcinogenesis

Background: Telomerase catalytic subunit (hTERT) gene re-expression is a rate limiting step for the activity of telomerase, a key enzyme implicated in cellular immortalisation and transformation. Aims: To determine the potential role of hTERT protein in gallbladder carcinogenesis. Material/Methods: hTERT protein was analysed by means of immunohistochemistry in 89 gallbladder tissue samples: 16 normal epithelia, 14 reactive hyperplasias, 15 low grade dysplasias, 16 high grade dysplasias, and 28 adenocarcinomas. At least 200 nuclei were assessed for each slide and the mean number of positive signals for each nucleus was expressed as the hTERT index. Results: The mean hTERT index increased progressively with the degree of gallbladder epithelial abnormalities: from 0.03 in normal epithelia, 0.04 in hyperplastic epithelia, 0.25 in low grade dysplasia, 0.82 in high grade dysplasia, to 0.93 in adenocarcinoma. Statistical analysis revealed that three different groups of gallbladder epithelial changes can be distinguished according to the number of hTERT signals for each nucleus: (1) normal and regenerative gallbladder epithelium, (2) low grade dysplasia, and (3) high grade dysplasia and adenocarcinoma (p < 0.001). Conclusions: The occasional presence of hTERT protein in normal and regenerative gallbladder mucosa reflects their regenerative capacity. Nevertheless, significantly higher hTERT indices in low and high grade dysplastic epithelia and in gallbladder adenocarcinomas are probably a consequence of hTERT re-expression—an early event in the multistep process of gallbladder carcinogenesis