The fatigue properties and fracture process of ion-nitrided steel 50H21G9N4

In the paper the fundamental fatigue properties of the valve steel 50H21G9N4 in delivery state and with modified after ionic nitrided surface layer are investigated. The fatigue strength of test pieces of such materials under cyclic loading are determine and their fracture processes are describe

Genetic variability of the grey wolf Canis lupus in the Caucasus in comparison with Europe and the Middle East: distinct or intermediary population?

Despite continuous historical distribution of the grey wolf (Canis lupus) throughout Eurasia, the species displays considerable morphological differentiation that resulted in delimitation of a number of subspecies. However, these morphological discontinuities are not always consistent with patterns of genetic differentiation. Here we assess genetic distinctiveness of grey wolves from the Caucasus (a region at the border between Europe and West Asia) that have been classified as a distinct subspecies C. l. cubanensis. We analysed their genetic variability based on mtDNA control region, microsatellite loci and genome-wide SNP genotypes (obtained for a subset of the samples), and found similar or higher levels of genetic diversity at all these types of loci as compared with other Eurasian populations. Although we found no evidence for a recent genetic bottleneck, genome-wide linkage disequilibrium patterns suggest a long-term demographic decline in the Caucasian population – a trend consistent with other Eurasian populations. Caucasian wolves share mtDNA haplotypes with both Eastern European and West Asian wolves, suggesting past or ongoing gene flow. Microsatellite data also suggest gene flow between the Caucasus and Eastern Europe. We found evidence for moderate admixture between the Caucasian wolves and domestic dogs, at a level comparable with other Eurasian populations. Taken together, our results show that Caucasian wolves are not genetically isolated from other Eurasian populations, share with them the same demographic trends, and are affected by similar conservation problems

Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study

Introduction: The use of anti-retroviral therapy (ART) has dramatically reduced HIV-1 associated morbidity and mortality. However, HIV-1 infected individuals have increased rates of morbidity and mortality compared to the non-HIV-1 infected population and this appears to be related to end-organ diseases collectively referred to as Serious Non-AIDS Events (SNAEs). Circulating miRNAs are reported as promising biomarkers for a number of human disease conditions including those that constitute SNAEs. Our study sought to investigate the potential of selected miRNAs in predicting mortality in HIV-1 infected ART treated individuals. Materials and Methods: A set of miRNAs was chosen based on published associations with human disease conditions that constitute SNAEs. This case: control study compared 126 cases (individuals who died whilst on therapy), and 247 matched controls (individuals who remained alive). Cases and controls were ART treated participants of two pivotal HIV-1 trials. The relative abundance of each miRNA in serum was measured, by RTqPCR. Associations with mortality (all-cause, cardiovascular and malignancy) were assessed by logistic regression analysis. Correlations between miRNAs and CD4+ T cell count, hs-CRP, IL-6 and D-dimer were also assessed. Results: None of the selected miRNAs was associated with all-cause, cardiovascular or malignancy mortality. The levels of three miRNAs (miRs -21, -122 and -200a) correlated with IL-6 while miR-21 also correlated with D-dimer. Additionally, the abundance of miRs -31, -150 and -223, correlated with baseline CD4+ T cell count while the same three miRNAs plus miR- 145 correlated with nadir CD4+ T cell count. Discussion: No associations with mortality were found with any circulating miRNA studied. These results cast doubt onto the effectiveness of circulating miRNA as early predictors of mortality or the major underlying diseases that contribute to mortality in participants treated for HIV-1 infection

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe

Analysis of Optimal Sets of Survivable Paths in Undirected Simple Graph Applicable for

In this work we introduce and describe optimal sets of survivable paths defined on an undirected simple graph G. An optimal set of survivable paths in G corresponds to a set of mesh-restored lightpaths in an optical network that minimizes the number of optical channels. We present several fundamental properties of optimal sets of survivable paths in G

Próby technologiczne napawania laserowego zaworów wylotowych silnika lotniczego

The results of technological tests of laser pad welding of faying surface of exhaust valves of ASz62IR piston aircraft engine have been presented in the paper. In the first stage of laboratory investigations using high power diode laser type ROFIN DL 020 as well as three kind of powders EuTroLoy 16006 and 16012 as well as AMI 3901 testes of pad welding were performed. On the samples made from 4H14N14W2M austenitic valve steel were selected optimal parameters of laser pad welding for individual powders. During second stage of investigations was carried out laser pad welding by stellite powders on the real elements - exhaust valves engine. As a result of pad welding of second final run of satellite following heating by laser ray as well as melting of surface layer of first final run, heating, melting and coating melted powder in liquid state on the base of first stelllite fine run, directive crystallization of melted material, phase changes occur from liquid to solid state. As a result of heating of base follow changes of microstructure as well as draw of deeper situated layers of first fine run of padding weld. After it was made pad welding of valves, it was used slow cooling, fore example in the heated quartz furnace(temperature about 250 to 350 oC) or cooling with furnace, what let on minimize of welding deformation as well as internal stresses. Pad wading layers were put to organoleptic verification, x-ray tests, laboratory investigations of microstructure and hardness. Created by laser pad welding surface layer characterized by fine-crystalline structure without weld defects, high homogeneity without precipitations and cracks as well as hardens on the surface equal 37+44 HRC . Technological tests of laser pad welding shout recognize as positive and augur perspectives of industry implementations.W artykule przedstawiono wyniki prób technologicznych napawania laserowego przylgni zaworów wylotowych tłokowego silnika lotniczego ASz62IR. W pierwszym etapie badań laboratoryjnych stosując laser diodowy dużej mocy typu ROFIN DL 020 oraz trzy rodzaje proszków EuTroLoy 16006 i 16012 oraz AMI 3901 wykonano próby napawania. Na próbkach ze stali zaworowej austenitycznej 4H14N14W2M dobrano optymalne parametry napawania laserowego dla poszczególnych proszków. W drugim etapie badań przeprowadzono napawanie laserowe proszkami stellitowymi na rzeczywistych elementach - zaworach wylotowych silnika. W wyniku napawania drugiego ściegu stellitu następuje nagrzewanie promieniem lasera oraz topnienie warstwy wierzchniej pierwszego ściegu, nagrzewanie, topnienie i nakładanie roztopionego proszku w stanie ciekłym na podłoże pierwszego ściegu stellitowego, krystalizacja kierunkowa roztopionego materiału, zachodzą przemiany fazowe ze stanu ciekłego w stały. W wyniku nagrzewania podłoża następują zmiany mikrostruktury oraz odpuszczanie głębiej położonych warstw pierwszego ściegu napoiny. Po wykonaniu napawania zaworów stosowano wolne studzenie, np. w rozgrzanym piasku kwarcowym (temp. ok. 250 - 350 oC) lub z piecem, co pozwoliło na zminimalizowanie odkształceń spawalniczych oraz naprężeń własnych. Napawane warstwy poddano weryfikacji organoleptycznej, badaniom rentgenowskim, badaniom laboratoryjnych mikrostruktury i twardości. Wytworzona poprzez napawanie laserowe warstwa wierzchnia charakteryzuje się budową drobnokrystaliczną bez wad spawalniczych, wysoką jednorodnością, bez wtrąceń i pęknięć oraz twardością na powierzchni równą 37+44 HRC. Próby technologiczne napawania laserowego należy uznać za pozytywne i rokujące perspektywy wdrożeń przemysłowych

Influence of powder laser welding of surface parameters on padding weld quality

W artykule przedstawiono wyniki badań wpływu zmian parametrów napawania na kształt oraz wybrane właściwości użytkowe warstw stellitowych laserowo napawanych na stalach zaworowych X53CrMnNiN 21-9 oraz X43CrSi 9-3. Badaniom poddano warstwy stellitowe napawane laserowo, plazmowo oraz techniką TIG, jak również materiał w stanie wyjściowym bez naniesionej warstwy stellitowej. Stwierdzono najwyższą odporność warstwy stellitowej na zużycie tribologiczne i utlenianie w wysokiej temperaturze dla elementów napawanych laserowo.The article presents experimental results of the influence of laser welding of surface parameters on the chosen usable proprieties of stellite layers on X53CrMnNiN 21-9 and X43CrSi 9-3 valve steels. Laser, plasma and TIG overlayer welding stellite layers were subjected to the tests as well as material being in the initial state, without the plotted stellite layer, was investigated. The highest resistance of the stellite layer was affirmed on abrasive wear and oxidation at high temperature for elements with powder laser overlayer welding surface