Leveraging SN Ia spectroscopic similarity to improve the measurement of H0H_0

Recent studies suggest spectroscopic differences explain a fraction of the variation in Type Ia supernova (SN Ia) luminosities after light-curve/color standardization. In this work, (i) we empirically characterize the variations of standardized SN Ia luminosities, and (ii) we use a spectroscopically inferred parameter, SIP, to improve the precision of SNe Ia along the distance ladder and the determination of the Hubble constant ($H_0$). First, we show that the \texttt{Pantheon+} covariance model modestly overestimates the uncertainty of standardized magnitudes by $\sim 7$%, in the parameter space used by the $\texttt{SH0ES}$ Team to measure $H_0$; accounting for this alone yields $H_0 = 73.01 \pm 0.92$ km s$^{-1}$ Mpc$^{-1}$. Furthermore, accounting for spectroscopic similarity between SNe~Ia on the distance ladder reduces their relative scatter to $\sim0.12$ mag per object (compared to $\sim 0.14$ mag previously). Combining these two findings in the model of SN covariance, we find an overall 14% reduction (to $\pm 0.85$km s$^{-1}$ Mpc$^{-1}$) of the uncertainty in the Hubble constant and a modest increase in its value. Including a budget for systematic uncertainties itemized by Riess et al. (2022a), we report an updated local Hubble constant with $\sim1.2$% uncertainty, $H_0 = 73.29 \pm 0.90$km s$^{-1}$ Mpc$^{-1}$. We conclude that spectroscopic differences among photometrically standardized SNe Ia do not explain the ``Hubble tension." Rather, accounting for such differences increases its significance, as the discrepancy against $\Lambda$CDM calibrated by the ${\it Planck}$ 2018 measurement rises to 5.7$\sigma$.Comment: 28 pages, 15 figures, accepted to JCA

Universal DNA methylation age across mammalian tissues

Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.Publisher PDFPeer reviewe

Universal DNA methylation age across mammalian tissues.

Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals

Productivity-oriented process parameters effect of the fatigue strength of SLMed Inconel 718

Metal additive manufacturing, in particular Selective Laser Melting (SLM), emerged as a technology suitable for the industrial production of structural components featuring complex geometries, i.e. internal cooling cavities, like the ones typical of the aerospace and power generation industries. In this field, nickel-based superalloys are used in a wide range of critical applications, characterized by the occurrence of severe environmental conditions and elevated stresses. The SLM process parameters play a fundamental role both in determining the mechanical performances of the component, in particular the fatigue strength, but are also the key parameter for increasing the productivity of the process and thus the industrial spread of the technology. In the present work, it is presented an experimental investigation, through HCF tests on plain and notched specimens, fractographic examinations, and metallographic analyses, of the effects of productivity-oriented process parameters on fatigue strength, surface quality, and microstructural defects, namely hot tearing cracks and porosities, of the Inconel 718 alloy. The experimental approach, along with a theoretical investigation of the thermal field produced by the SLM process, will be used to define a feasible region in terms of scan velocity, laser power, layer thickness, and scan strategy

SLM process parameters effects on the fatigue strength of AMed Inconel 718

Selective Laser Melting (SLM) emerged as a technology suitable for the industrial production of structural components featuring complex geometries. In the field of elevated temperature applications, the possibilities offered by the SLM can be successfully used to produced complex geometries as internal cooling channels or lattice structures, as long as the process doesn’t jeopardize the mechanical properties, in particular the fatigue strength. The SLM process parameters play a fundamental role in determining the mechanical performances of the component but are also the key parameter for increasing the productivity of the process and thus the industrial spread of the technology. In the present work, it is presented an experimental assessment of the effects produced by different sets of productivity-oriented SLM process parameters on the Wöehler curves of cylindrical plain specimens. The adopted process parameters were defined on the basis of a previously developed thermal analytical model aimed to predict the melt pool dimensions and shape. HCF tests were carried out at room temperature in an axial load configuration with a stress ratio of 0.05 and a loading frequency of about 150 Hz, by using a resonant testing machine. Test frequency was monitored to detect the occurrence of crack nucleation and monitor the propagation phase. In order to understand the causes of the fatigue behavior, metallographic analyses were carried out to investigate the microstructural properties or the presence of internal defects, i.e. porosity and hot tearing cracks, produced by each set of process parameters. The surface quality was also investigated in detail through optical microscope analyses. Fractographic analyses were used to identify the nucleation and crack propagation region, as well as the presence of the defects in proximity to the fracture onset. The experimental data, along with an analytical model of the thermal field produced by a single scan line, allowed to define a preliminary feasible region for the SLM process on Inconel 718, in terms of scan velocity, laser power, layer thickness, and scan strategy

Dataset of dimensionless operating conditions for welding and metal additive manufacturing

The present dataset contains the dimensionless operating conditions obtained by processing a wide range of welding and metal Additive Manufacturing (AM) process parameters through a unified theoretical framework based on the Rosenthal solution [1]. The exploratory data analysis covered Arc and Beam Welding (AW and BW, respectively) on various materials, joint types, and bead sizes ranging from 0.5 to over 10 mm. As for AM, we considered Laser Metal Deposition (LMD) and Selective Laser Melting (SLM) on steel, Al, Ni, Ti, Cu, and Co-Cr alloys by limiting the research to the last five years of published literature.Nomenclature:UVelocity magnitudePPowerpWelding power (AW and BW)dDistance between adjacent scan lines (SLM)sNominal layer thickness (SLM)Τ0Initial or preheating temperatureR ̅ Melt pool half-widthArMelt pool aspect ratioŨDimensionless velocityP ̃Dimensionless powerWelding joint types are identified by the initials B, L, and T, standing for Butt, Lap, and T- joints, respectively.[1] M. Moda, A. Chiocca, G. Macoretta, B.D. Monelli, L. Bertini, Technological implications of the Rosenthal solution for a moving point heat source in steady state on a semi-infinite solid, Mater. Des. (2022). https://doi.org/10.1016/j.matdes.2022.110991THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Dataset of dimensionless operating conditions for welding and metal additive manufacturing

The present dataset contains the dimensionless operating conditions obtained by processing a wide range of welding and metal Additive Manufacturing (AM) process parameters through a unified theoretical framework based on the Rosenthal solution [1]. The exploratory data analysis covered Arc and Beam Welding (AW and BW, respectively) on various materials, joint types, and bead sizes ranging from 0.5 to over 10 mm. As for AM, we considered Laser Metal Deposition (LMD) and Selective Laser Melting (SLM) on steel, Al, Ni, Ti, Cu, and Co-Cr alloys by limiting the research to the last five years of published literature.Nomenclature:UVelocity magnitudePPowerpWelding power (AW and BW)dDistance between adjacent scan lines (SLM)sNominal layer thickness (SLM)Τ0Initial or preheating temperatureR ̅ Melt pool half-widthArMelt pool aspect ratioŨDimensionless velocityP ̃Dimensionless powerWelding joint types are identified by the initials B, L, and T, standing for Butt, Lap, and T- joints, respectively.[1] M. Moda, A. Chiocca, G. Macoretta, B.D. Monelli, L. Bertini, Technological implications of the Rosenthal solution for a moving point heat source in steady state on a semi-infinite solid, Mater. Des. (2022). https://doi.org/10.1016/j.matdes.2022.110991THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

HCF assessment of additively manufactured notched specimens in Inconel 718

Exploiting the potential of metal Additive Manufacturing (AM) mainly means the ability to produce complex geometries in high-performance materials. It implies that AMed components present several notches (holes, grooves, and shoulders), both on external and internal surfaces. A fatigue assessment of AMed components of industrial interest must deal with notch effects: multiaxial stresses and stress concentration. Inconel 718 is a widespread material for AMed components used in high-temperature applications, which typically feature complex geometries and notches. Criteria developed for dealing with notches in traditionally manufactured components, such as the Average Strain Energy Density (ASED), can be extended to AMed specimens including the effects introduced by the manufacturing process. In the present work, it is analyzed the room temperature HCF behavior of as-built notched and smooth cylindrical specimens in the framework of the criteria present in the literature. Three geometries of V-notches, resembling the ones typically present in industrial components and featuring a k_t in the range between 1.5 and 3.0, were considered. High cycle fatigue tests were carried out at room temperature in an axial load configuration with a stress ratio of 0.05 and a loading frequency of about 150 Hz, by using a resonant machine. It was analyzed the life region between 10^4 and 10^6 cycles. Fractographic analyses, carried out with a Scanning Electron Microscope (SEM), were used to identify the nucleation and crack propagation region, as well as the presence of the defects in proximity to the fracture onset. Microstructural investigations were also carried out to investigate grain dimension and growth direction, as well as the presence of internal porosity and hot tearing cracks. Optical microscope analyses were finally used to investigate the surface quality in proximity to the fracture nucleation regions

Improved model for the prediction of the residual stress field in autofrettaged cylinders

The stress-strain curve in a loading-unloading process of high-strength steels can be significantly affected by the previous stress-strain history. In particular, if the material has accumulated plastic strain, the elastic modulus can decrease and the Bauschinger effect can impact the plastic response. The combined effect of the reduction of the elastic modulus and the Bauschinger effect can affect the residual stress field in autofrettaged cylindrical pressure vessels. In particular, the value of the compressive residual stress at the bore is, at the same time, the one most impacted by the loss of either strength or stiffness and the one that bottle-necks the pressure vessel performances. An experimental campaign has been performed to accurately measure the constitutive behavior for the high-strength steel of an autofrettaged component. Uniaxial tests were performed on specimens extracted from the above mentioned autofrettaged component. A complete 3-D incremental elastic-plastic constitutive model has been tuned to reproduce the observed behavior. This model, implemented in the ANSYS® commercial Code via User Programmable Features, has then been used to simulate the autofrettage process. The residual stress field, obtained via the proposed FE simulation, was compared with the distribution measured on the component by means of the slitting method. The comparison was used to assess the validity of the proposed constitutive model and its numerical implementatio