Ventricular function, myocardial delayed enhancement and patient-reported quality of life in adolescents and adults with repaired tetralogy of Fallot

INTRODUCTION: In patients with repaired tetralogy of Fallot (TOF), right ventricular myocardial delayed enhancement (MDE) and diastolic dysfunction are common, and have been associated with decreased exercise capacity and increased arrhythmia. Predictors of quality of life (QOL) have not been reported in this population. PURPOSE: We assessed the hypothesis that a greater degree of MDE in adolescents and adults with repaired TOF would correlate with diastolic dysfunction and decreased QOL

Ventricular function, myocardial delayed enhancement and patient-reported quality of life in adolescents and adults with repaired tetralogy of Fallot

INTRODUCTION: In patients with repaired tetralogy of Fallot (TOF), right ventricular myocardial delayed enhancement (MDE) and diastolic dysfunction are common, and have been associated with decreased exercise capacity and increased arrhythmia. Predictors of quality of life (QOL) have not been reported in this population. PURPOSE: We assessed the hypothesis that a greater degree of MDE in adolescents and adults with repaired TOF would correlate with diastolic dysfunction and decreased QOL

Calorimetric observations of amorphous and crystalline Ni-Zr alloy formation by solid-state reaction

Differential scanning calorimetry and x-ray diffraction are utilized in a study of solid-state vitrification of multilayered composites of Ni and Zr. In order to understand better and optimize the amorphizing reaction, we have examined the kinetics of competing reactions: the formation and growth of crystalline intermetallic compounds. The value of the activation energy, Ec, of the initial crystallization of the growing amorphous phase is determined to be Ec=2.0±0.1 eV, establishing an upper limit on the thermal stability of the amorphous-diffusion couple

Calorimetric study of amorphization in planar, binary, multilayer, thin-film diffusion couples of Ni and Zr

We have utilized differential scanning calorimetry to monitor the solid-state reaction of crystalline metals to form an amorphous alloy in multilayered thin-film diffusion couples of elemental Ni and Zr. The heat of formation of amorphous Ni68Zr32 alloy from the elemental metals is measured directly and found to be 35 ± 5 kJ/mole. The kinetics of these reactions has been examined. The activation energy for interdiffusion in the amorphous phase is determined to be E=1.05±0.05 eV

Random walk with barriers: Diffusion restricted by permeable membranes

Restrictions to molecular motion by barriers (membranes) are ubiquitous in biological tissues, porous media and composite materials. A major challenge is to characterize the microstructure of a material or an organism nondestructively using a bulk transport measurement. Here we demonstrate how the long-range structural correlations introduced by permeable membranes give rise to distinct features of transport. We consider Brownian motion restricted by randomly placed and oriented permeable membranes and focus on the disorder-averaged diffusion propagator using a scattering approach. The renormalization group solution reveals a scaling behavior of the diffusion coefficient for large times, with a characteristically slow inverse square root time dependence. The predicted time dependence of the diffusion coefficient agrees well with Monte Carlo simulations in two dimensions. Our results can be used to identify permeable membranes as restrictions to transport in disordered materials and in biological tissues, and to quantify their permeability and surface area.Comment: 8 pages, 3 figures; origin of dispersion clarified, refs adde

Dynamic lattice distortions driven by surface trapping in semiconductor nanocrystals

Nonradiative processes limit optoelectronic functionality of nanocrystals and curb their device performance. Nevertheless, the dynamic structural origins of nonradiative relaxations in nanocrystals are not understood. Here, femtosecond electron diffraction measurements corroborated by atomistic simulations uncover transient lattice deformations accompanying radiationless electronic processes in semiconductor nanocrystals. Investigation of the excitation energy dependence shows that hot carriers created by a photon energy considerably larger than the bandgap induce structural distortions at nanocrystal surfaces on few picosecond timescales associated with the localization of trapped holes. On the other hand, carriers created by a photon energy close to the bandgap result in transient lattice heating that occurs on a much longer 200 ps timescale, governed by an Auger heating mechanism. Elucidation of the structural deformations associated with the surface trapping of hot holes provides atomic-scale insights into the mechanisms deteriorating optoelectronic performance and a pathway towards minimizing these losses in nanocrystal devices.Comment: 17 pages, 4 figure

Quantitative permeability imaging of plant tissues

A method for mapping tissue permeability based on time-dependent diffusion measurements is presented. A pulsed field gradient sequence to measure the diffusion encoding time dependence of the diffusion coefficients based on the detection of stimulated spin echoes to enable long diffusion times is combined with a turbo spin echo sequence for fast NMR imaging (MRI). A fitting function is suggested to describe the time dependence of the apparent diffusion constant in porous (bio-)materials, even if the time range of the apparent diffusion coefficient is limited due to relaxation of the magnetization. The method is demonstrated by characterizing anisotropic cell dimensions and permeability on a subpixel level of different tissues of a carrot (Daucus carota) taproot in the radial and axial directions