QRS micro-fragmentation as a mortality predictor.

AIMS Fragmented QRS complex with visible notching on standard 12-lead electrocardiogram (ECG) is understood to represent depolarization abnormalities and to signify risk of cardiac events. Depolarization abnormalities with similar prognostic implications likely exist beyond visual recognition but no technology is presently suitable for quantification of such invisible ECG abnormalities. We present such a technology. METHODS AND RESULTS A signal processing method projects all ECG leads of the QRS complex into optimized three perpendicular dimensions, reconstructs the ECG back from this three-dimensional projection, and quantifies the difference (QRS 'micro'-fragmentation, QRS-μf) between the original and reconstructed signals. QRS 'micro'-fragmentation was assessed in three different populations: cardiac patients with automatic implantable cardioverter-defibrillators, cardiac patients with severe abnormalities, and general public. The predictive value of QRS-μf for mortality was investigated both univariably and in multivariable comparisons with other risk factors including visible QRS 'macro'-fragmentation, QRS-Mf. The analysis was made in a total of 7779 subjects of whom 504 have not survived the first 5 years of follow-up. In all three populations, QRS-μf was strongly predictive of survival (P < 0.001 univariably, and P < 0.001 to P = 0.024 in multivariable regression analyses). A similar strong association with outcome was found when dichotomizing QRS-μf prospectively at 3.5%. When QRS-μf was used in multivariable analyses, QRS-Mf and QRS duration lost their predictive value. CONCLUSION In three populations with different clinical characteristics, QRS-μf was a powerful mortality risk factor independent of several previously established risk indices. Electrophysiologic abnormalities that contribute to increased QRS-μf values are likely responsible for the predictive power of visible QRS-Mf. KEY QUESTION KEY FINDING TAKE-HOME MESSAGE QRS-μf is a strong predictor of worsened survival. It can be assessed in standard short-term 12-lead electrocardiograms

Brownian motors: noisy transport far from equilibrium

Transport phenomena in spatially periodic systems far from thermal equilibrium are considered. The main emphasize is put on directed transport in so-called Brownian motors (ratchets), i.e. a dissipative dynamics in the presence of thermal noise and some prototypical perturbation that drives the system out of equilibrium without introducing a priori an obvious bias into one or the other direction of motion. Symmetry conditions for the appearance (or not) of directed current, its inversion upon variation of certain parameters, and quantitative theoretical predictions for specific models are reviewed as well as a wide variety of experimental realizations and biological applications, especially the modeling of molecular motors. Extensions include quantum mechanical and collective effects, Hamiltonian ratchets, the influence of spatial disorder, and diffusive transport.Comment: Revised version (Aug. 2001), accepted for publication in Physics Report

Epoxy-Anhydride Vitrimers from Aminoglycidyl Resins with High Glass Transition Temperature and Efficient Stress Relaxation

Epoxy-anhydride vitrimers are covalent adaptable networks, which undergo associative bond exchange reactions at elevated temperature. Their service temperature is influenced by the glass transition temperature (Tg) as well as the topology freezing transition temperature (Tv), at which the covalent bond exchange reactions become significantly fast. The present work highlights the design of high-Tg epoxy-anhydride vitrimers that comprise an efficient stress relaxation at elevated temperature. Networks are prepared by thermally curing aminoglycidyl monomers with glutaric anhydride in different stoichiometric ratios. The tertiary amine groups present in the structure of the aminoglycidyl derivatives not only accelerate the curing reaction but also catalyse the transesterification reaction above Tv, as shown in stress relaxation measurements. The topology rearrangements render the networks recyclable, which is demonstrated by reprocessing a grinded powder of the cured materials in a hot press. The epoxy-anhydride vitrimers are characterised by a high Tg (up to 140 &deg;C) and an adequate storage modulus at 25 &deg;C (~2.5 GPa), which makes them interesting candidates for structural applications operating at high service temperature

Structure–activity correlations in thin film model catalysts: CO hydrogenation on Rh/VOx Part I. The morphology, composition and structure of vanadia-supported and -promoted Rh particles upon oxidation and reduction

The combination of (high-resolution) electron microscopy and electron diffraction was applied to study the structural and morphological alterations of a number of Rh/VOx-model systems upon oxidation and reduction, and to discriminate between different phenomena of metal–support interaction. Well-defined Rh particles (mean size 10–15 nm) were grown epitaxially on NaCl(001) surfaces and subsequently covered by layers of VOx of varying thickness (0.07–2 nm), prepared by reactive deposition of V metal in 10−2 Pa O2. Most films were covered with a stabilizing layer of amorphous alumina. The resulting model catalysts were subjected to an oxidative treatment at 673 K in O2 for 1 h and to subsequent reduction in the temperature range 373–873 K. While higher VOx exposures (mean VOx coverage ≥ 3 nm) favour the formation of crystalline V2O3 phases in partial epitaxial orientation to the Rh particles in the as-deposited state, lower exposures result in less ordered layers of cubic VO. Similarly, after a treatment in 1 bar O2 at 673 K the oxidation states of vanadium vary between V5+ and V2+, depending on the film thickness. Decoration of Rh by reduced VOx species was found to be the dominant feature of metal–support interaction upon reduction at low temperatures (T < 573 K), whereas at increasing reduction temperature the formation of distinct Rh–V alloys (V3Rh5, Rh3V, V3Rh and VRh, respectively) was observed. On a “VOx/Rh/Al2O3” catalyst, prepared by depositing 1ML VOx prior to Rh deposition alloy formation was not detected, and decoration of the metal particles was the dominant effect of reduction at 673 K. A counterpart to Rh/V “subsurface” or “surface” alloys, known to be formed on bulk Rh surfaces under similar conditions, could not be observed