Yeast hexokinase isoenzyme ScHxk2: stability of a two-domain protein with discontinuous domains

The hexokinase isoenzyme 2 of Saccharomyces cerevisiae (ScHxk2) represents an archetype of a two-domain protein with the active site located in a cleft between the two domains. Binding of the substrate glucose results in a rigid body movement of the two domains leading to a cleft closure of the active site. Both domains of this enzyme are composed of discontinuous peptide sequences. This structural feature is reflected in the stability and folding of the ScHxk2 protein. Structural transitions induced by urea treatment resulted in the population of a thermodynamically stable folding intermediate, which, however, does not correspond to a molecule with one domain folded and the other unfolded. As demonstrated by different spectroscopic techniques, both domains are structurally affected by the partial denaturation. The intermediate possesses only 40% of the native secondary structural content and a substantial increase in the Stokes radius as judged by circular dichroism and dynamic light scattering analyses. One-dimensional 1H NMR data prove that all tryptophan residues are in a non-native environment in the intermediate, indicating substantial changes in the tertiary structure. Still, the intermediate possesses quite a high stability for a transition intermediate of about ΔG = -22 kJ mol?1.     

Visual SLAM: Why filter?

While the most accurate solution to off-line structure from motion (SFM) problems is undoubtedly to extract as much correspondence information as possible and perform batch optimisation, sequential methods suitable for live video streams must approximate this to fit within fixed computational bounds. Two quite different approaches to real-time SFM – also called visual SLAM (simultaneous localisation and mapping) – have proven successful, but they sparsify the problem in different ways. Filtering methods marginalise out past poses and summarise the information gained over time with a probability distribution. Keyframe methods retain the optimisation approach of global bundle adjustment, but computationally must select only a small number of past frames to process.     

Zur Bemessung von Lochleisten als duktile Verbundmittel in Verbundträgern aus höherfesten Materialien

Im Rahmen eines gemeinsamen FuE‐Projekts der HOCHTIEF Construction AG und ArcelorMittal Belval & Differdange S. A. wurden umfangreiche experimentelle und theoretische Untersuchungen an Lochleisten als duktiles Verbundmittel durchgeführt. Ziel der Untersuchung ist die Entwicklung technisch hochwertiger und wirtschaftlicher Verbundbauteile aus höherfesten Werkstoffen (z. B. Beton C50/60 und Stahl S460), [1] bis [4]. Hierbei wurden insbesondere das Tragverhalten, die Traglast, die Duktilität und die Dauerfestigkeit von unterschiedlichen Lochleistenformen sowie das Gesamttragverhalten von Verbundbauteilen mit Lochleisten untersucht. Aufbauend auf den in Versuchen gewonnenen Erkenntnisse wurden Bemessungskonzepte für Lochleisten als Verbundmittel in Verbundträgern aus höherfesten Materialien entwickelt. Design of aperture plates as ductile shear connectors for composite beams with high strength materials. Within a joint research project of HOCHTIEF Construction AG and ArcelorMittal Belval & Differdange S. A. various experimental and theoretical investigations in aperture plates, as ductile shear connector for composite members have been carried out. The aim of the research has been to develop technically advanced and economic composite members with the application of high strength materials (e.g. steel S460 and concrete C50/60). The main focus of the research has been put on the load bearing behaviour, ultimate bearing capacity, ductility and fatigue resistance of different types of aperture plates geometries as well as the related overall bearing performance of the composite members with the application of these plates as shear connectors. Based on the conclusions from the experimental test results, design concepts for aperture plates as shear connectors for composite beams with the application of high strength materials have been developed.     

Electroosmotic flow stimulates the release of alginate-bound phenanthrene

There is growing interest in employing electro-bioremediation, a hybrid technology of bioremediation and electrokinetics for the treatment of contaminated soil. Most present applications of electrokinetics aim at pollutant extraction, which requires transport over large distances facilitated by electroosmotic flow (EOF). They do not explicitly account for the possibility that EOF passing along soil particles stimulates the release of hydrophobic organic compounds (HOC) and locally improves pollutant bioavailability. Here, we report on the stimulated release of polycyclic aromatic hydrocarbon (phenanthrene) from model organic matter in the presence of direct current (DC)-electric fields (0.5-2 V cm(-1)) typically used in electrobioremediation measures. Alginate beads were employed as a model polymer release system (MPRS) exhibiting similar release behavior as natural organic matter (NOM). In the presence of EOF the phenanthrene release flux from alginate beads was between 1.4- and 1.8-fold higher than under hydraulic flow conditions with equal bulk water velocity and 30-120-fold higherthan under stagnantwater conditions. Our data suggest that DC-electric fields (0.5-2 V cm(-1)) can stimulate the release of PAH bound to particles exposed to stagnant water zones often found at hydraulic flow regimes restricted by low permeability.     

Artificial neural network study of whole-cell bacterial bioreporter response determined using fluorescence flow cytometry

Genetically engineered bioreporters are an excellent complement to traditional methods of chemical analysis. The application of fluorescence flow cytometry to detection of bioreporter response enables rapid and efficient characterization of bacterial bioreporter population response on a single-cell basis. In the present study, intrapopulation response variability was used to obtain higher analytical sensitivity and precision. We have analyzed flow cytometric data for an arsenic-sensitive bacterial bioreporter using an artificial neural network-based adaptive clustering approach (a single-layer perceptron model). Results for this approach are far superior to other methods that we have applied to this fluorescent bioreporter (e.g., the arsenic detection limit is 0.01 microM, substantially lower than for other detection methods/algorithms). The approach is highly efficient computationally and can be implemented on a real-time basis, thus having potential for future development of high-throughput screening applications.     

Model polymer release system study of PAH bioaccessibility: the relationship between "rapid" release and bioaccessibility

This paper examines bacterial uptake of polycyclic aromatic hydrocarbons (PAHs) entrained within model polymer release systems (MPRSs) whose release kinetics, particularly for operationally defined "slow" release, are similarto PAH release kinetics from sediments and soils. We find that biodegradation is not restricted to the fraction "rapidly" released, f1, as quantified by an empirical biphasic exponential fitting parameter. Though our results indicate that f1 does not predict bioaccessibility (defined by a recent paper calling for a standard definition of same), we analyze the causes of the reported limitation of biodegradation to rapidly released PAHs and we find that, for the MPRSs, there are very strong correlations between an ad hoc bioaccessibility and a wide range of fitting parameters from various kinetic expressions used to phenomenologically characterize release. These results indicate that fitting parameters may be used to predict ad hoc bioaccessibility; however, it is not clear if this is actually a particularly useful quantity. We also report experimental results which indicate that bacteria may influence their environment and cause biological uptake to exceed that expected from abiotic release data obtained under quasi-infinite sink conditions. When this occurs, fitting parameters from simple empirical expressions are even inadequate to predict ad hoc bioaccessibility.     

Material behaviour and plant experience of P91/P92 components

In several lignite-fired power plants of the ‘Vattenfall Generation AG’ in Germany components of P91/P92 material are used in long-time operation. About this experience in operation of selected components will be reported. In this context own experimental results of a research project in the damage evolution will be presented. The project ‘Damage development III’ was edited together with the MPA Stuttgart and was supported by Vattenfall and AVIF. The aim of the project was to improve the knowledge about the process of creep damage by experimental tests and additional numerical calculations. An instruction was given for planning, implementation and analysis of recurrent investigations on components consisting of 9% Cr steels which are subjected to high operation loading. Finally, the damage phenomena are presented by two case studies, a damage in a pipe bend due to faulty heat treatment and the creep-crack assessment of a lack of side-wall fusion in a reheater weld by fracture mechanics.     

Variational subgrid scale formulations for the advection–diffusion-reaction equation

The exact variational multiscale (VMS) and the subgrid scale (SGS) methods have been developed for the advection-reaction and the advection–diffusion-reaction equations. From the element Green's function, approximate intrinsic time scale parameters have been derived for these cases and are shown to be similar to other expressions obtained in the literature out of the maximum principle and convergence/error analysis. The methods have been compared with typical stabilized finite element methods. As expected, the VMS is nodally exact for the one-dimensional case.