Search results for "Elastic"

Local ex-vivo evaluation of the biomechanical properties of the ascending aortic aneurysms

2019

Introduction Currently, surgical recommendations for aneurysm of the ascending aorta (AsAA) are based on the maximum diameter of the ascending aorta, but this factor is not reliable. Understanding the biomechanical properties of the aorta could lead to improve the prediction of the development of an AsAA. The aim of this study is to obtain the local patient specific elastic modulus distribution of the AsAA from a biaxial tensile test. Methods Pathologic ascending aortic tissue samples (n = 10) were obtained from patients undergoing elective surgical repair of AsAA ( Table 1 ). All the aortic wall samples were partitioned related to medial, posterior, lateral, and anterior quadrants. Each As…

089 Autofluorescence imaging for non-invasive visualization and quantification of skin lesions of patients with pseudoxanthoma elasticum

2021

Automated classification of focal breast lesions according to S-detect: validation and role as a clinical and teaching tool

2018

Abstract PURPOSE: To assess the diagnostic performance and the potential as a teaching tool of S-detect in the assessment of focal breast lesions. METHODS: 61 patients (age 21-84 years) with benign breast lesions in follow-up or candidate to pathological sampling or with suspicious lesions candidate to biopsy were enrolled. The study was based on a prospective and on a retrospective phase. In the prospective phase, after completion of baseline US by an experienced breast radiologist and S-detect assessment, 5 operators with different experience and dedication to breast radiology performed elastographic exams. In the retrospective phase, the 5 operators performed a retrospective assessment a…

Effect of apolar phase dielectric constant on interfacial properties of β-lactoglobulin (dielectric constant and interfacial properties of β-lactoglo…

2005

International audience; In this work, we hypothesized that the difference in the dielectric constant value existing between two non-miscible phases such as oil and water could be partially responsible for both protein unfolding and reorganization of the protein structure at the interface. So, we replaced the oil phase, whose dielectric constant value is 2, by organic solvents chosen for both their non-miscibility with water and their range of dielectric constant values higher (range 6.1-7.2) than that of oil. Using a dynamic drop tensiometer, we studied both surface activity and viscoelastic properties of the milk protein at various interfaces. The aqueous phase (pH7; 25°C) contained the co…

Structure, ferroelasticity and Goldilocks zone phase transitions in C3H5N2Al(SO4)2·6H2O

2021

The single crystal growth and sequence of reversible phase transition are described for C3H5N2Al(SO4)2·6H2O. Thermal and structural analyses combined with dielectric studies and optical observations revealed the structural phase transition at T 1 = 339/340 K (I↔II) and T 2 = 347/348 K (II↔III) on heating and cooling, respectively. Both phase transitions are of the first-order type. The symmetry changes from monoclinic to trigonal phase. At 293 K, the large crystals are usually divided into numerous domains of the ferroelastic type that disappear above T 1 on heating and reappear below T 1 on cooling. The domain structure pattern is characteristic for the transition between trigonal and mono…

Persistence Length of Cylindrical Brush Molecules Measured by Atomic Force Microscopy

2006

Mechanical properties of single cylindrical polymer brushes with polyisopropylacrylamide (PNIPAM) side chains deposited on mica were probed by atomic force microscopy. Visualization and stretching of individual molecules in aqueous solution clearly reveal the semiflexible nature of the cylindrical macromolecules. Imaging of the brushes on mica and inferring lp from a 〈R2〉 vs L plot results in an average persistence length of lp = 29 ± 3 nm, assuming the chains adopt their equilibrium conformation on the surface. Stretching experiments suggest that an exact determination of the persistence length using force extension curves is impeded by the contribution of the side-chain elasticity. Modeli…

Liver stiffness, a non-invasive marker of liver disease: a core study group report

2010

The ability to evaluate liver stiffness non-invasively in clinical practice by measuring transient elastography using FibroScan® has resulted in considerable interest and enthusiasm. A core study group, organized by the Italian Association for the Study of the Liver, has assessed the usefulness of FibroScan® in the diagnosis and management of liver disease in clinical practice. The group concluded that FibroScan® is a valuable, non-invasive technique and have developed a consensus report form for registering transient elastography results. In this article, we report the findings of the study group.

The Role of Diffusion Accommodation and Phase Boundary Wetting in the Deformation Behaviour of Ultrafine Grained Sn-Pb Eutectic

2010

Mechanical properties, microstructure of the Sn–38wt. %Pb eutectic and the development of deformation - induced diffusion processes on interphase boundaries (IB) were investigated. Experiments were carried out both in deformed and annealed states of eutectic using micro- and nanoindentation, SEM, AFM and optical microscopy techniques. It was found that the deformation of the annealed alloy is localized at the Pb/Sn interphase boundaries and occurs by grain boundary sliding (GBS) accompanied by sintering micropore processes under the action of the capillary forces on the Pb/Sn IB. During severe plastic deformation of Sn-Pb eutectic phase transition in the Sn grain boundary occurs. This defor…

Irreversibility of the pressure-induced phase transition of quartz and the relation between three hypothetical post-quartz phases

2004

Our atomistic computer simulations mainly based on classical force fields suggest that the pressure-induced transition from $\ensuremath{\alpha}$ quartz to quartz II at $21\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$ is irreversible. While quartz II is ferroelastic in principle, the transition itself is coelastic, as the shape of the newly formed crystal is determined by the handedness of $\ensuremath{\alpha}$-quartz. Upon releasing the pressure, our model quartz II remains stable down to $5\phantom{\rule{0.3em}{0ex}}\mathrm{GPa}$, where it undergoes an isosymmetric transformation into a less dense polymorph. If the classical force field model of quartz II is compressed quickly to $50\phantom{\…

Field-induced ordering phenomena and non-local elastic compliance in two-dimensional colloidal crystals

2008

Ordering phenomena in colloidal dispersions exposed to external one-dimensional, periodic fields or under confinement are studied systematically by Monte Carlo computer simulations. Such systems are useful models for the study of monolayers on a substrate. We find that the interaction with a substrate potential completely changes the miscibility of a binary, hard disc mixture at low external field amplitudes. The underlying ordering mechanisms leading to this laser-induced de-mixing differ, depending on which components interact with the substrate potential. Generic effects of confinement on crystalline order in two dimensions are studied in a model system of point particles interacting via…