Enzyme activity of α‐chymotrypsin after derivatization with phenolic compounds

α‐Chymotrypsin was allowed to react with selected phenolic and related compounds (chlorogenic acid, m‐, o‐, p‐dihydroxybenzene, p‐benzoquinone). The derivatized enzymes obtained were characterized in terms of their activity. In vitro experiments illustrated that the enzymatic activity of the derivatives was adversely affected. The kinetics of the enzymatic reactions showed that the hydrolysis of selected food proteins becomes slower and the affinity of the enzyme to these substrates declined as measured by Michaelis‐Menten constant and maximum velocity of the enzymatic reaction. This enzyme inhibition depended on the reactivity of the phenolic and related substances tested as well as on the degree of the derivatization. Further, influence of the enzyme‐substrate ratio was also demonstrated. The effects of the derivatization are more pronounced with increasing concentration of the substrates.     

Hardware in the loop simulation of production systems dynamics

Constantly growing competitive pressure forces machine and plant manufacturers to find new innovative ways to reduce the development costs as well as to increase the quality. In order to achieve these goals, simulation tools are used in many phases of the development process. An integrated simulation of the system “production plant” requires not only the dynamic behavior of the production system but also the consideration of the applied control technology. For this purpose, especially the coupled simulation between real control system and virtual machine became widely accepted in recent years. This paper will give an overview of the current state of the art of hardware-in-the-loop simulation of production systems dynamics at the ISW.     

A probabilistic model for automatic segmentation of the esophagus in 3-D CT scans

Being able to segment the esophagus without user interaction from 3-D CT data is of high value to radiologists during oncological examinations of the mediastinum. The segmentation can serve as a guideline and prevent confusion with pathological tissue. However, limited contrast to surrounding structures and versatile shape and appearance make segmentation a challenging problem. This paper presents a multistep method. First, a detector that is trained to learn a discriminative model of the appearance is combined with an explicit model of the distribution of respiratory and esophageal air. In the next step, prior shape knowledge is incorporated using a Markov chain model. We follow a "detect and connect" approach to obtain the maximum a posteriori estimate of the approximate esophagus shape from hypothesis about the esophagus contour in axial image slices. Finally, the surface of this approximation is nonrigidly deformed to better fit the boundary of the organ. The method is compared to an alternative approach that uses a particle filter instead of a Markov chain to infer the approximate esophagus shape, to the performance of a human observer and also to state of the art methods, which are all semiautomatic. Cross-validation on 144 CT scans showed that the Markov chain based approach clearly outperforms the particle filter. It segments the esophagus with a mean error of 1.80 mm in less than 16 s on a standard PC. This is only 1 mm above the interobserver variability and can compete with the results of previously published semiautomatic methods.     

Chemoenzymatic Preparation of Functional Click-Labeled Messenger RNA

Synthetic mRNAs are promising candidates for a new class of transformative drugs that provide genetic information for patients’ cells to develop their own cure. One key advancement to develop so-called druggable mRNAs was the preparation of chemically modified mRNAs, by replacing standard bases with modified bases, such as uridine with pseudouridine, which can ameliorate the immunogenic profile and translation efficiency of the mRNA. Thus the introduction of modified nucleobases was the foundation for the clinical use of such mRNAs. Herein we describe modular and simple methods to chemoenzymatically modify mRNA. Alkyne- and/or azide-modified nucleotides are enzymatically incorporated into mRNA and subsequently conjugated to fluorescent dyes using click chemistry. This allows visualization of the labeled mRNA inside cells. mRNA coding for the enhanced green fluorescent protein (eGFP) was chosen as a model system and the successful expression of eGFP demonstrated that our modified mRNA is accepted by the translation machinery.     

Identification and quantification of flavonol aglycons in cactus pear (Opuntia ficus indica) fruit using a commercial pectinase and cellulase preparation

The applicability of pectinases and cellulases as soft hydrolysing agents on flavonol glycosides was investigated for identification and quantification of flavonol aglycons in cactus pear fruit. Freeze-dried samples of cactus pear fruit’s peel (cactus pear peels) and onions were treated with commercial pectinase and cellulase preparations at 50 °C for different time periods (up to 16 h). Additionally isorhamnetin-3-O-rutinoside and quercetin-3,4′-O-diglucoside were used as model compounds. In parallel, samples of cactus pear peels and onions were treated by the traditional acidic hydrolysis using HCl. Following hydrolysis, flavonols were characterised using HPLC–DAD. Enzymatically, all model compounds and plant material were highly hydrolysable. Flavonol glycosides were completely hydrolysed after 16 h (cactus pear) and 4 h (onion), respectively. While the acidic hydrolysis caused degradation of the flavonols and produced protocatechuic acid as a degradation product, the enzymatic hydrolysis gave gentle effects and did not produce any protocatechuic acid at all.     

In Situ Characterization of Deformation Behavior of Austenitic High Manganese Steels

The mechanical properties of high manganese steels are linked to their hardening mechanisms and their intrinsic behavior during deformation. The characterization of mechanical properties is influenced by the localization of plastic flow and the effect of this localization on the material. Depending on grain size, temperature, and extrinsic strain rate localization of strain, adiabatic heating, and hardening vary in spatial and temporal extent. Even at small strain rates the adiabatic heating of samples reaches temperatures more than 100 K over initial testing temperature due to the sharp localization and last but not least this heating is also dependent on the tested sample size. Furthermore, temperature influences the activated mechanisms of plastic flow. The characterization of temperature increase, strain distribution, and local hardening is pursued in tensile tests with application of infrared thermography. With those techniques it is possible to gather correlations between local strain and temperature. The analysis of dynamic strain ageing effects is also carried out by evaluation of the instantaneous strain rate, the strain rate in the gauge length, in dependence of stress in different alloys, as well as at different strain rate regimes. Thus it is possible to distinguish the onset of TRIP, TWIP and DSA.     

Eine Methode zur Ermittlung der anwendungsspezifischen Leistungsgrenze trockenlaufender Friktionspaarungen

Forschung im Ingenieurwesen - Eine immer grenzwertigere Auslegung trockenlaufender Friktionssysteme sowie die Steigerung der bauraum- und massenspezifischen Leistungsdichte führen zu permanent...     

Trockene Desagglomeration von Nanopartikelagglomeraten in einer Sichtermühle

Production of aerosol by dry dispersion is important for many technical processes, e.g., coating. The desagglomeration of materials from the product class nanoparticle flocks is a specific challenge. An insight in results and experiences by the dry desagglomeration with an air classifier mill (jet mill) is given. The variable main influences are the cage wheel ratio, the process air flow, the specific surface of the model substances and the length of the transport pipe.     

Forschungsansätze zur Effizienzsteigerung heutiger IT-Frühwarnsysteme

Anstrengungen zur Verbesserung der Sicherheit von vernetzten Systemen konzentrieren sich auf das Schlie?en von Sicherheitslücken und die Identifikation auftretender Schadsoftware (Malware). Malware-Autoren begegnen diesen Bemühungen mit der Entwicklung neuer oder abgewandelter Angriffsformen. Um diesbezüglich mithalten und zeitnah reagieren zu k?nnen, ist es notwendig, diese Fortschritte mit Hilfe von IT-Frühwarnsystemen zu erkennen und zu verfolgen, neue Wirkweisen zu verstehen und die bestehenden Schutzsysteme um geeignete Gegenma?nahmen zu erg↭zen.