Evaluation of FEM electric field analysis using the electric properties of giant unilamellar vesicles (GUV) and Jurkat cells measured by electrorotation spectroscopy: Introduction of cryo‐ and lyoprotectants by electrofusion of GUVs and living cells

Electrofusion of giant unilamellar vesicles (GUVs) and living cells is a gentle method for delivering membrane impermeable cryo‐/lyo‐protective molecules into living cells for cryo‐/lyopreservation. In this method, an optimal length and strength of an electric pulse are required to initiate GUV‐cell fusion. Calculating the electric field by the finite element method (FEM) might be a powerful analytical method for prediction of the optimal pulse length and strength of a deformed and adhered GUV‐cell. The objective of this study is to clarify whether an FEM model of a pulsed GUV or cell could be applicable for prediction of its electric field, especially the change of membrane potential. First, electric properties of GUVs and Jurkat cells were derived from electrorotation spectra with a dipole approximation model. Secondly, the electric field and the membrane potential of a single GUV or cell after applying a stepwise electric field were calculated by an FEM model using the measured electric properties. At the first stage after applying a step electric field, the calculated membrane potential by the FEM model shows good agreement with the membrane potential derived from the dipole approximation model. After complete relaxation of the electric field, the calculated membrane potential of the FEM model is lower than that of the dipole approximation model. This might be because both models do not take into account the effects of electric double layers on both sides of the membrane. © 2009 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20242     

Unified Modeling of Fluid or Granular Flows on Dam-Break Case

The stopping process of debris-flow pulses is a complex phenomenon that expresses both the characteristics of a non-Newtonian fluid when it flows and those of a soil when it comes to a stop. In order to capture this phenomenon, we have developed a model based on a Navier-Stokes approach with a constitutive law including a Drucker-Prager yield criterion. The latter permits us to continuously describe the passage of granular material from the flowing (viscous) to the stopped (viscoplastic) status. In addition to being easy to implement, this approach has the advantage of being straightforwardly expandable to full three-dimensional modeling. In order to evaluate this approach, we have implemented it using finite elements. This implementation uses a Galerkin finite-element approximation with a least-squares stabilization procedure. The free surface is treated by means of a level-set approach to cope with the complex geometry of a flowing pulse. The rheological model and the free-surface treatment are tested in an analytical problem and in a dam-break test.     

Modelling and Closed‐loop Control of Complex Tube Forming Based on an Optimized Application of Martensite Formation in Austenitic Stainless Steels

Metastable austenitic steels undergo deformation‐induced martensitic transformation which can lead to a distinct increase of fatigue strength at an optimal volume fraction of martensite. This effect was used in the present study to define the local strength behaviour of a structural component part for the very high cycle fatigue (VHCF) regime. The investigation was on a discontinuous two‐stage forming process that consists of U‐O‐forming and rotary draw bending and results in a cross tube of a trailer coupling as exemplary dynamically loaded component. The volume fraction of martensite can be adjusted by means of plastomechanical simulation of the forming process and its parameters as part of the online process control. The formation of martensite shows a strong dependence on forming parameters (e.g. temperature and strain‐rate) and batch variations. These disturbance variables can only be taken into account by a closed‐loop control. Non‐isothermal material models were analysed according to their simulation accuracy of the martensite evolution. For the online control various hierarchical mathematical models were studied with regard to time effort and model error.     

Comparative evaluation of the efficacy of cereal and microbial phytases in growing pigs fed diets with marginal phosphorus supply

Two experiments with a total of 76 growing pigs (average initial body weight 16.6 kg) were conducted to compare the efficacy of cereal phytases (wheat and rye) and supplemented microbial phytase (Natuphos®). Using the slope ratio technique, the dose–response relationship between five levels of phytase (0, 50, 100, 150 and 200 U kg^?1) and the apparent absorption of phosphorus (P) within each source of phytase was calculated. Graded phytase levels in the diets were obtained by adding increasing amounts of microbial phytase or phytase‐containing wheat (Exp 1) or rye (Exp 2) to phytase‐inactivated basal diets at the expense of phytase‐inactivated wheat (Exp 1) or rye (Exp 2). Except for wheat phytase, addition of phytase to the basal diets increased (P < 0.05) apparent P absorption, with microbial phytase being more efficient (P < 0.05) than cereal phytase. There were no significant differences in apparent P absorption between the wheat‐ or rye‐based diets when either microbial or cereal phytases were supplemented from 0 to 200 U kg^?1. It could be derived from the results of this study, by means of regression analysis, that the efficacy of cereal phytases was 40% compared to microbial phytase. © 2002 Society of Chemical Industry     

Non destructive determination of the free chloride content in cement based materials

A non‐destructive chloride sensitive sensor element for use in cement based porous materials is presented. The sensor element determines the activity of the free chloride ions in solutions and in porous cement based materials such as cement paste, mortar or concrete. The calibration in synthetic pore solution showed a response according to Nernst law over three decades of chloride concentration. The sensor element has shown excellent reproducibility and long term stability. The sensor element has been used to monitor the chloride uptake into mortar specimens. The results show a good agreement between the free chloride content determined by the sensor and by pore water expression. Applications in monitoring of reinforced concrete structures and their limitations are discussed.     

RMI system: Internet meets the future home theatre

The Remote Media Immersion (RMI) system blends multiple cutting-edge media technologies to create the ultimate digital media delivery platform. Its streaming media server delivers multiple high-bandwidth streams, transmission resilience and flow-control protocols ensure data integrity, and high-definition video combined with immersive audio provide the highest quality rendering.     

Highly sensitive wide-dynamic range optical burst-mode receivers for ultra fast gain switching

Highly sensitive optical receivers in BiCMOS, sub-micron and deep-sub-micron CMOS technology are compared. Special attention is paid to burst-mode receivers with a wide-dynamic input range and with fast gain switching. A new burst-mode receiver design in 0.12μm CMOS technology for a data rate of 2.5 Gb/s and very fast gain switching is presented. Handling a wide dynamic range leads to stability problems when the transimpedance gain of the preamplifier is decreased. These stability problems could be solved by decreasing the open-loop gain of the transimpedance amplifier. Stability analysis of this solution is presented here. Kerstin Schneider was born in St. Poelten, Austria, on February 15, 1975. She received the Dipl. Ing. degree from the Vienna University of Technology, Austria, in 2000. In 2004 she received her Dr. techn. degree at the Vienna University of Technology, Austria. Since 2001 she is with the Vienna University of Technology, Institute for Electrical Measurements and Circuit Design, Vienna, Austria. She is author of the Springer book ‘Highly Sensitive Optical Receivers’. Her major fields of interest are optoelectronics and integrated circuit design. Horst Zimmermann (M’98–SM’02) born in Sulzbach-Rosenberg, Bavaria, on 27 December 1957 studied Physics in Bayreuth, Germany, and received the Dr.-Ing. degree in the Fraunhofer Institute for Integrated Circuits (IIS-B), Erlangen, Germany in 1991. Then, Dr. Zimmermann was an Alexander-von-Humboldt Research-Fellow at Duke University, Durham, N.C., where he worked on diffusion in Si, GaAs, and InP until 1992. In 1993, he joined the Chair for Semiconductor Electronics at Kiel University, where he lectured optoelectronics and worked on optoelectronic integration. Since 2000 he is professor for Electronic Circuit Design at the Vienna University of Technology, Vienna, Austria. His main interests are in design and characterization of analog deep-sub-micron CMOS circuits and optoelectronic integrated CMOS and BiCMOS circuits. He is author of the Springer books ‘Integrated Silicon Optoelectronics’ and ‘Silicon Optoelectronic Integrated Circuits’ and co-author of ‘Highly Sensitive Optical Receivers’ as well as author and co-author of more than 140 publications.     

Chemical Genetic Approaches for the Investigation of Neutral Lipid Metabolism

The coordinated processes of lipid synthesis, degradation, and transport are mediated by enzymes, cofactors, and transport proteins. Accordingly, lipid‐metabolizing enzymes represent logical targets for the treatment of dyslipidemia, a major risk factor for type 2 diabetes, atherosclerosis, and other disorders. Small‐molecule tool compounds, modulating the functions of such proteins, can substantially facilitate the characterization of target proteins. Such molecules complement genetic studies, and allow time‐ and dose‐dependent control of protein activity in biological systems. This can improve our understanding of physiological processes, give insights into the druggability of target proteins, and might finally result in the development of therapeutic compounds. In this review we summarize the current state of available inhibitors targeting key proteins in neutral lipid metabolism, with a focus on metabolic lipases, acyltransferases, and fatty‐acid‐binding proteins.