New Structured Materials in the Study of the Mechanobiological Processes Related to the Heart Failure

Cardiovascular diseases are the number one of death globally. According to the World Health organization 17.7 million people died from cardiovascular diseases in 2015, representing 31% of all global deaths.  In these diseases the cardiac homeostasis is disrupted by a non-appropriate myocardium remodelling. The cardiac extracellular matrix (ECM) provides not only the biochemical environment but also a natural scaffold surrounding and connecting cardiac cells and distributing mechanical forces throughout the organ. Thus, the properties of the ECM are essential for the maintenance of the functional myocardium. Alterations in cardiac ECM structure associated with heart failure influence cell-matrix and cell-cell adhesions modifying cell shape and mechanotransduction.The need to understand the cardiac ECM remodelling mechanisms that allow us to identify new therapeutic targets lead us to create biomimetic scaffolds which emulate the structure, topography, mechanics and chemical composition of ECM.Here, we present the development of modulable materials for the manufacturing, by using photopolymerizable materials, of structured hydrogels with myocardium properties of stiffness and elastic modulus in physiological and pathological conditions

New Structured Materials in the Study of the Mechanobiological Processes Related to the Heart Failure

Cardiovascular diseases are the number one of death globally. According to the World Health organization 17.7 million people died from cardiovascular diseases in 2015, representing 31% of all global deaths. In these diseases the cardiac homeostasis is disrupted by a non-appropriate myocardium remodelling. The cardiac extracellular matrix (ECM) provides not only the biochemical environment but also a natural scaffold surrounding and connecting cardiac cells and distributing mechanical forces throughout the organ. Thus, the properties of the ECM are essential for the maintenance of the functional myocardium. Alterations in cardiac ECM structure associated with heart failure influence cell-matrix and cell-cell adhesions modifying cell shape and mechanotransduction. The need to understand the cardiac ECM remodelling mechanisms that allow us to identify new therapeutic targets lead us to create biomimetic scaffolds which emulate the structure, topography, mechanics and chemical composition of ECM. Here, we present the development of modulable materials for the manufacturing, by using photopolymerizable materials, of structured hydrogels with myocardium properties of stiffness and elastic modulus in physiological and pathological conditions

Non-adiabatic small polaron hopping in the n=3 Ruddlesden-Popper compound Ca4Mn3O10

Magnetotransport properties of the compound Ca4Mn3O10 are interpreted in terms of activated hopping of small magnetic polarons in the non-adiabatic regime. Polarons are most likely formed around Mn3+ sites created by oxygen substoichiometry. The application of an external field reduces the size of the magnetic contribution to the hopping barrier and thus produces an increase in the conductivity .We argue that the change in the effective activation energy around TN is due to the crossover to VRH conduction as antiferromagnetic order sets in.Comment: 29 pages, 7 figure

Data-Driven Computational Simulation in Bone Mechanics.

The data-driven approach was formally introduced in the field of computational mechanics just a few years ago, but it has gained increasing interest and application as disruptive technology in many other fields of physics and engineering. Although the fundamental bases of the method have been already settled, there are still many challenges to solve, which are often inherently linked to the problem at hand. In this paper, the data-driven methodology is applied to a particular problem in tissue biomechanics, a context where this approach is particularly suitable due to the difficulty in establishing accurate and general constitutive models, due to the intrinsic intra and inter-individual variability of the microstructure and associated mechanical properties of biological tissues. The problem addressed here corresponds to the characterization and mechanical simulation of a piece of cortical bone tissue. Cortical horse bone tissue was mechanically tested using a biaxial machine. The displacement field was obtained by means of digital image correlation and then transformed into strains by approximating the displacement derivatives in the bone virtual geometric image. These results, together with the approximated stress state, assumed as uniform in the small pieces tested, were used as input in the flowchart of the data-driven methodology to solve several numerical examples, which were compared with the corresponding classical model-based fitted solution. From these results, we conclude that the data-driven methodology is a useful tool to directly simulate problems of biomechanical interest without the imposition (model-free) of complex spatial and individually-varying constitutive laws. The presented data-driven approach recovers the natural spatial variation of the solution, resulting from the complex structure of bone tissue, i.e. heterogeneity, microstructural hierarchy and multifactorial architecture, making it possible to add the intrinsic stochasticity of biological tissues into the data set and into the numerical approach

A multiscale data-driven approach for bone tissue biomechanics

The data-driven methodology with application to continuum mechanics relies upon two main pillars: (i) experimental characterization of stress–strain pairs associated to different loading states, and (ii) numerical elaboration of the elasticity equations as an optimization (searching) algorithm using compatibility and equilibrium as constraints. The purpose of this work is to implement a multiscale data-driven approach using experimental data of cortical bone tissue at different scales. First, horse cortical bone samples are biaxially loaded and the strain fields are recorded over a region of interest using a digital image correlation technique. As a result, both microscopic strain fields and macroscopic strain states are obtained by a homogenization procedure, associated to macroscopic stress loading states which are considered uniform along the sample. This experimental outcome is here referred as a multiscale dataset. Second, the proposed multiscale data-driven methodology is implemented and analyzed in an example of application. Results are presented both in the macroscopic and microscopic scales, with the latter considered just as a post-process step in the formulation. The macroscopic results show non-smooth strain and stress patterns as a consequence of the tissue heterogeneity which suggest that a preassumed linear homogeneous orthotropic model may be inaccurate for bone tissue. Microscopic results show fluctuating strain fields – as a consequence of the interaction and evolution of the microconstituents – an order of magnitude higher than the averaged macroscopic solution, which evidences the need of a multiscale approach for the mechanical analysis of cortical bone, since the driving force of many biological bone processes is local at the microstructural level. Finally, the proposed multiscale data-driven technique may also be an adequate strategy for the solution of intractable large size multiscale FE computational approaches since the solution at the microscale is obtained as a postprocessing. As a main conclusion, the proposed multiscale data-driven methodology is a useful alternative to overcome limitations in the continuum mechanical study of the bone tissue. This methodology may also be considered as a useful strategy for the analysis of additional biological or technological hierarchical multiscale materials.The authors gratefully acknowledge the support of Ministerio de Economía y Competitividad del Gobierno España, Spain through the grants DPI2014-58233-P, DPI2017-82501-P, and PGC2018-097257-B-C31; as well as Consejería de Economía y Conocimiento de la Junta de Andalucía, Spain (US-1261691, FEDER, UE)

Structure-properties changes in ZnO-PbO-GeO 2 glasses

We have studied the structure of ZnO-PbO-GeO2 glasses by Fourier transform infrared spectroscopy and showed that the analysis of the vibrational spectra can lead to a quantitative description of the network structure in terms of the fraction of the local germanate polyhedra. The presence of GeO4, GeO6 and GeO4 with NBOs units was evidenced in the studied glass network. The initial additions of ZnO would introduce modifier Zn2+ ions at the expense of the former PbO4 units. With increasing ZnO content, ZnO4 tetrahedra would mainly replace modifier PbO. The decrease in density when introducing ZnO at the expense of PbO content is not only due to the vast difference in molecular mass between PbO and ZnO, but also due to the formation of Q2 and Q3 units. The glass network of the investigated glasses posseses a more covalent character upon replacing ZnO for PbO. This is the reason for increasing the microhardness and the glass transformation temperature of the glasses investigated with increasing zinc oxide content. The change in the conductivity at certain temperature not only attributed to the change in the covalency of the glass matrix upon replacing PbO by ZnO but also due to a change in the strain energy because of the change in Vm

The Influence of Aluminum on Indium and Tin Behaviour during Secondary Copper Smelting

Aluminum and copper are large volume metals in electronic appliances, while tin and indium exist as common minor elements. All of these non-ferrous metals are aimed to be separated and recycled from the end-of-life electronics into non-ferrous scrap fraction(s), and further through pyrometallurgical and/or hydrometallurgical processes to pure metals. Depending on the mechanical pre-treatment processes, aluminum and copper liberation from each other varies. This study focuses on the influence of alumina on indium and tin distributions between copper alloy and iron silicate slags with 0, 9 and ~16 wt% of Al2O3. The experiments were executed with an equilibration-quenching-EPMA technique in an oxygen pressure range of 10−10–10−5 atm at 1300 ℃. The metal-slag distribution coefficient of indium remains constant as a function of alumina in slag, while that of tin increases. Therefore, aluminum in feed or alumina addition to the slag improves the recovery of tin into copper. Nevertheless, oxygen pressure has clearlymore significant influence on the behavior of both the metals in the smelting conditions.Peer reviewe