Wrocław University of Technology

About: Wrocław University of Technology is a education organization based out in Wrocław, Poland. It is known for research contribution in the topics: Laser & Computer science. The organization has 13115 authors who have published 31279 publications receiving 338694 citations.

Unnatural amino acids increase sensitivity and provide for the design of highly selective caspase substrates

Abstract: Traditional combinatorial peptidyl substrate library approaches generally utilize natural amino acids, limiting the usefulness of this tool in generating selective substrates for proteases that share similar substrate specificity profiles. To address this limitation, we synthesized a Hybrid Combinatorial Substrate Library (HyCoSuL) with the general formula of Ac-P4-P3-P2-Asp-ACC, testing the approach on a family of closely related proteases – the human caspases. The power of this library for caspase discrimination extends far beyond traditional PS-SCL approach, as in addition to 19 natural amino acids we also used 110 diverse unnatural amino acids that can more extensively explore the chemical space represented by caspase-active sites. Using this approach we identified and employed peptide-based substrates that provided excellent discrimination between individual caspases, allowing us to simultaneously resolve the individual contribution of the apical caspase-9 and the executioner caspase-3 and caspase-7 in the development of cytochrome-c-dependent apoptosis for the first time.

Nitrogen-containing chitosan-based carbon as an electrode material for high-performance supercapacitors

Abstract: Nitrogen-containing activated carbons were prepared from chitosan, a widely available and inexpensive biopolysaccharide, by a simple procedure and tested as electrode material in supercapacitors. The physical activation of chitosan chars with CO2 led to carbons with a very high nitrogen content (up to 5.4 wt%) and moderate surface areas (1000–1100 m2 g−1). Only chitosan-based activated carbons with a similar microporous structure were considered in this study to evaluate the effect of the nitrogen content and distribution on their electrochemical performance. The N-containing activated carbons were tested in two- and three-electrode supercapacitors using an aqueous electrolyte (1 M H2SO4), and they exhibited superior surface capacitance (19.5 µF cm−2) and pseudocapacitance compared to a commercial activated carbon with a negligible nitrogen content and similar microporosity. The low oxygen content and the presence of stable quaternary nitrogen improved the charge propagation on the chitosan-based carbons, which was confirmed by the high capacity retention of 83 %. The chitosan-based carbons exhibited excellent cyclic stability and maintained 100 % of their capacitance after 5000 charge/discharge cycles at a current density of 1 A g−1. These results demonstrate the suitability of chitosan-based carbons for application in energy storage systems.

Quantum kinetic theory of phonon-assisted excitation transfer in quantum dot molecules.

Abstract: We present a quantum-kinetic theory of the excitation transfer in a quantum dot molecule. We derive the consistent Markovian limit for the system kinetics, which leads to a description in terms of a single transfer rate for weak coupling. We show that the transfer rate is a strongly varying, nonmonotonic function of the spatial separation and energy mismatch between the dots.

The Order of Approximations for Solutions of Itô-Type Stochastic Differential Equations with Jumps

Abstract: In this paper we consider so called strong Taylor approximations for processes, which are solutions of Ito-type SDEs with jumps driven by the homogeneous Poisson process. We give the order of convergence of such approximations in ℒ2-norm, that depends on an accepted difference scheme, and show the explicit formula of the order 1 scheme.

A fast and accurate implementation of tunable algorithms used for generation of fractal-like aggregate models

Abstract: In many branches of science experiments are expensive, require specialist equipment or are very time consuming. Studying the light scattering phenomenon by fractal aggregates can serve as an example. Light scattering simulations can overcome these problems and provide us with theoretical, additional data which complete our study. For this reason a fractal-like aggregate model as well as fast aggregation codes are needed. Until now various computer models, that try to mimic the physics behind this phenomenon, have been developed. However, their implementations are mostly based on a trial-and-error procedure. Such approach is very time consuming and the morphological parameters of resulting aggregates are not exact because the postconditions (e.g. the position error) cannot be very strict. In this paper we present a very fast and accurate implementation of a tunable aggregation algorithm based on the work of Filippov et al. (2000). Randomization is reduced to its necessary minimum (our technique can be more than 1000 times faster than standard algorithms) and the position of a new particle, or a cluster, is calculated with algebraic methods. Therefore, the postconditions can be extremely strict and the resulting errors negligible (e.g. the position error can be recognized as non-existent). In our paper two different methods, which are based on the particle–cluster (PC) and the cluster–cluster (CC) aggregation processes, are presented.