On the asymmetry of the forward and reverse martensitic transformations in shape memory alloys

Differential Scanning Calorimetric, DSC, runs taken during martensitic phase transformations in shape memory alloys, often look differently during cooling and heating. Similar asymmetry is observed e.g. for the numbers of hits or the critical exponents of energy and amplitude distributions (\epsilon and \alpha, respectively) in acoustic emission measurements. It is illustrated that, in accordance with empirical correlations, the above asymmetry of acoustic noises can be classified into two groups: the relative changes of the exponents during cooling and heating (\gamma \epsilon=(\epsilon h-\epsilon c)/\epsilon c as well as \gamma \alpha=(\alpha h-\alpha c)/\alpha c)) are either positive or negative. For positive \gamma values the number of hits and the total energy of acoustic emission are larger for cooling, and the situation is just the reverse for negative asymmetry. Our interpretation is based on the different ways of relaxation of the elastic strain energy during cooling as well as heating. It is illustrated that if the relaxed fraction of the total elastic strain energy (which would be stored without relaxations) during cooling is larger than the corresponding relaxed fraction during heating, then the asymmetry is positive. Magnetic emission noises, accompanied with martensitic phase transformations in ferromagnetic alloys, show similar asymmetry than those observed for thermal (DSC) and acoustic noises and depends on the constant external magnetic field too

Perceived Age Discrimination as a Mediator of the Association Between Income Inequality and Older People's Self-Rated Health in the European Region

Objectives. The relative income hypothesis predicts poorer health in societies with greater income inequality. This article examines whether the psychosocial factors of perceived age discrimination and (lack of) social capital may help explain the adverse effect of inequality on older people's health. Methods. Self-rated health, perceived age discrimination, and social capital were assessed in the 2008/9 European Social Survey (European Social Survey Round 4 Data, 2008). The Gini coefficient was used to represent national inequalities in income in each of the 28 European Social Survey countries. Mediation analyses (within a multilevel structural equation modeling paradigm) on a subsample of respondents over 70 years of age (N = 7,819) were used to examine whether perceived age discrimination mediates the negative effect of income inequality on older people's self-rated health. Results. Perceived age discrimination fully mediated the associations between income inequality and self-rated health. When social capital was included into the model, only age discrimination remained a significant mediator and predictor of self-rated health. Discussion. Concrete instances of age discrimination in unequal societies are an important psychosocial stressor for older people. Awareness that the perception of ageism can be an important stressor and affect older patient's self-reported health has important implications for the way health practitioners understand and treat the sources of patient's health problems in later life.info:eu-repo/semantics/acceptedVersio

Extracellular Matrix in Heart Failure: Role of ADAMTS5 in Proteoglycan Remodeling

[Abstract] Background: Remodeling of the extracellular matrix (ECM) is a hallmark of heart failure (HF). Our previous analysis of the secretome of murine cardiac fibroblasts returned ADAMTS5 (a disintegrin and metalloproteinase with thrombospondin motifs 5) as one of the most abundant proteases. ADAMTS5 cleaves chondroitin sulfate proteoglycans such as versican. The contribution of ADAMTS5 and its substrate versican to HF is unknown. Methods: Versican remodeling was assessed in mice lacking the catalytic domain of ADAMTS5 (Adamts5ΔCat). Proteomics was applied to study ECM remodeling in left ventricular samples from patients with HF, with a particular focus on the effects of common medications used for the treatment of HF. Results: Versican and versikine, an ADAMTS-specific versican cleavage product, accumulated in patients with ischemic HF. Versikine was also elevated in a porcine model of cardiac ischemia/reperfusion injury and in murine hearts after angiotensin II infusion. In Adamts5ΔCat mice, angiotensin II infusion resulted in an aggravated versican build-up and hyaluronic acid disarrangement, accompanied by reduced levels of integrin β1, filamin A, and connexin 43. Echocardiographic assessment of Adamts5ΔCat mice revealed a reduced ejection fraction and an impaired global longitudinal strain on angiotensin II infusion. Cardiac hypertrophy and collagen deposition were similar to littermate controls. In a proteomics analysis of a larger cohort of cardiac explants from patients with ischemic HF (n=65), the use of β-blockers was associated with a reduction in ECM deposition, with versican being among the most pronounced changes. Subsequent experiments in cardiac fibroblasts confirmed that β1-adrenergic receptor stimulation increased versican expression. Despite similar clinical characteristics, patients with HF treated with β-blockers had a distinct cardiac ECM profile. Conclusions: Our results in animal models and patients suggest that ADAMTS proteases are critical for versican degradation in the heart and that versican accumulation is associated with impaired cardiac function. A comprehensive characterization of the cardiac ECM in patients with ischemic HF revealed that β-blockers may have a previously unrecognized beneficial effect on cardiac chondroitin sulfate proteoglycan content.Dr Barallobre-Barreiro is a British Heart Foundation Intermediate Fellow (FS/19/33/34328). Drs Mayr and Shah are British Heart Foundation Chair Holders (CH/16/3/32406 and CH/1999001/11735, respectively) and received support from the British Heart Foundation Center for Vascular Regeneration With Edinburgh/Bristol (RM/17/3/33381). Dr Doménech’s work was supported by Project PI16/02049 integrated in the National Plan for Scientific Research, Development and Technological Innovation, 2013–2016, and funded by the ISCIII–General Subdirection of Assessment and Promotion of Research–European Regional Development Fund. Dr Merkely’s work was funded by the National Research, Development and Innovation Fund (NVKP_16-1–2016-0017) and the Thematic Excellence Program of the Ministry for Innovation and Technology (2020-4.1.1.-TKP2020), Hungary. Dr Radovits is supported by the National Research, Development and Innovation Office of Hungary (K134939)British Heart Foundation; FS/19/33/34328British Heart Foundation; CH/16/3/32406British Heart Foundation; CH/1999001/11735British Heart Foundation Center for Vascular Regeneration; RM/17/3/33381Hungría. Ministry for Innovation and Technology; NVKP_16-1–2016-0017Hungría. Ministry for Innovation and Technology; 2020-4.1.1.-TKP2020Hungría. National Research, Development and Innovation Office; K13493

Possible extracardiac predictors of aortic dissection in Marfan syndrome

BACKGROUND: According to previous studies, aortic diameter alone seems to be insufficient to predict the event of aortic dissection in Marfan syndrome (MFS). Determining the optimal schedule for preventive aortic root replacement (ARR) aortic growth rate is of importance, as well as family history, however, none of them appear to be decisive. Thus, the aim of this study was to search for potential predictors of aortic dissection in MFS. METHODS: A Marfan Biobank consisting of 79 MFS patients was established. Thirty-nine MFS patients who underwent ARR were assigned into three groups based on the indication for surgery (dissection, annuloaortic ectasia and prophylactic surgery). The prophylactic surgery group was excluded from the study. Transforming growth factor-beta (TGF-beta) serum levels were measured by ELISA, relative expression of c-Fos, matrix metalloproteinase 3 and 9 (MMP-3 and -9) were assessed by RT-PCR. Clinical parameters, including anthropometric variables - based on the original Ghent criteria were also analyzed. RESULTS: Among patients with aortic dissection, TGF-beta serum level was elevated (43.78 +/- 6.51 vs. 31.64 +/- 4.99 ng/l, p < 0.0001), MMP-3 was up-regulated (Ln2alpha = 1.87, p = 0.062) and striae atrophicae were more common (92% vs. 41% p = 0.027) compared to the annuloaortic ectasia group. CONCLUSIONS: We found three easily measurable parameters (striae atrophicae, TGF-beta serum level, MMP-3) that may help to predict the risk of aortic dissection in MFS. Based on these findings a new classification of MFS, that is benign or malignant is also proposed, which could be taken into consideration in determining the timing of prophylactic ARR

Ancient chicken remains reveal the origins of virulence in Marek's disease virus

This is the author accepted manuscript. The final version is available from the American Association for the Advancement of Science via the DOI in this recordData and materials availability: All MDV sequence data generated have been deposited in GenBank under accession PRJEB64489. Code is available at GitHub (https://github.com/antonisdim/MDV) and archived at Zenodo (https://zenodo.org/records/10022436) (25).The pronounced growth in livestock populations since the 1950s has altered the epidemiological and evolutionary trajectory of their associated pathogens. For example, Marek's disease virus (MDV), which causes lymphoid tumors in chickens, has experienced a marked increase in virulence over the past century. Today, MDV infections kill >90% of unvaccinated birds, and controlling it costs more than US$1 billion annually. By sequencing MDV genomes derived from archeological chickens, we demonstrate that it has been circulating for at least 1000 years. We functionally tested the Meq oncogene, one of 49 viral genes positively selected in modern strains, demonstrating that ancient MDV was likely incapable of driving tumor formation. Our results demonstrate the power of ancient DNA approaches to trace the molecular basis of virulence in economically relevant pathogens.European Research Council (ERC)Wellcome TrustOxford Martin School Pandemic Genomics ProgrammeArts and Humanities Research Council (AHRC)European Union Horizon 2020Biotechnology and Biological Sciences Research Council (BBSRC)Research Foundation–Flanders (Fonds voor Wetenschappelijk Onderzoek

Investigations of Solid Phase Processes in CuAlNi Base Shape Memory Alloys

Cu based Shape Memory Alloys are favored because of their high transformation temperatures and low price. However, their brittle behavior and the ageing processes due to cycle heating limit the alloys’ practicability. To extend their suitability, Mn and Fe were added to the base CuAlNi alloy in order to increase ductility. The ageing processes and the effect of the Mn and Fe addition were examined using differential scanning calorimetry, optical microscopy, scanning electron microscopy, transmission electron microscopy and in-situ optical microscopy. Transformation temperatures shifted to higher temperatures in the CuAlNi alloy as the ageing time was increased. In CuAlNiMn and CuAlNiMnFe alloys the thermoelastic martensitic transformation disappeared in the aged samples. The cause of this effect turned out to be an exothermic process starting at around 300°C, which was previously not known. The examinations were focused to characterize and identify this exothermic process

On the temperature and stress dependence of transformation strain in single crystalline Cu-Al-Ni shape memory alloys

In the austenite to martensite phase transformation of shape memory alloys the transformation strain, εtr, usually has definite dependence on the external fields while the change in entropy or volume can be considered constant. Under uniaxial loading this dependence of εtr is related to the change of the martensite variant distribution with increasing field parameters. The stress and temperature dependence of the elastic and dissipative energy contributions to the transformation can be correlated with the η dependence of εtr, where η is the volume fraction of the stress induced (single) variant martensite structure. Obviously, this dependence leads to deviation from the linear Clausius-Clapeyron relation too. In this paper we discuss and compare experimental results in single crystalline Cu17.9wt.%Al-2.6wt.%Ni and Cu-11.5wt%-Al5.0wt%Ni alloys obtained from stress-strain and strain-temperature hysteretic loops at different constant temperatures and stresses, respectively. Furthermore, it is shown that the field dependence of εtr is reflected in the field dependence of the dissipative and elastic energy terms too