163 Works

A host-vector toolbox for improved secretory protein overproduction in bacillus subtilis

Anna Krüger, Norma Welsch, Alexandra Dürwald, Henrike Brundiek, Rainer Wardenga, Henning Piascheck, Hendrik G. Mengers, Jana Krabbe, Sandra Beyer, Johannes Kabisch, Lutz Popper, Tanno Hübel, Garabed Antranikian & Thomas Schweder
Abstract: Target proteins in biotechnological applications are highly diverse. Therefore, versatile flexible expression systems for their functional overproduction are required. In order to find the right heterologous gene expression strategy, suitable host-vector systems, which combine different genetic circuits, are useful. In this study, we designed a novel Bacillus subtilis expression toolbox, which allows the overproduction and secretion of potentially toxic enzymes. This toolbox comprises a set of 60 expression vectors, which combine two promoter variants,...

Performance increase of wave energy harvesting of a guided point absorber

Marten Hollm, Leo Dostal, Daniil Yurchenko & Robert Seifried
The dynamics of a novel wave energy converter based on a guided inclined point absorber are investigated. Thereby, it is studied through simulations and experiments whether different inclination angles of the guided point absorber lead to larger motion amplitudes and velocities in regular and irregular waves, from which energy can be harvested. For that, different simulations and experimental setups are analyzed in the presence of wave forcing. In the case of irregular waves a random...

Topology-based initialization for the optimization-based design of heteroazeotropic distillation processes

Kai Kruber & Mirko Skiborowski
Distillation-based separation processes, such as extractive or heteroazeotropic distillation, present important processes for separating azeotropic mixtures in the chemical and biochemical industry. However, heteroazeotropic distillation has received much less attention than extractive distillation, which can be attributed to multiple reasons. The phase equilibrium calculations require a correct evaluation of phase stability, while the topology of the heterogeneous mixtures is generally more complex, comprising multiple azeotropes and distillation regions, resulting in an increased modeling complexity. Due...

Effect of different interval lengths in a rolling horizon MILP unit commitment with non-linear control model for a small energy system

Gerrit Erichsen, Tobias Zimmermann & Alfons Kather
In this paper, a fixed electricity producer park of both a short- and long-term renewable energy storage (e.g., battery, power to gas to power) and a conventional power plant is combined with an increasing amount of installed volatile renewable power. For the sake of simplicity, the grid is designed as a single copper plate with island restrictions and constant demand of 1000 MW; the volatile input is deducted from scaled 15-min input data of German...

Low-power Iron selection and focus field generator

Fynn Förger, Marija Boberg, Martin Möddel, Jan-Philipp Scheel, Matthias Gräser & Tobias Knopp
A major issue for human-sizedMagnetic Particle Imaging scanners is the generation of sufficiently large magnetic gradient fields. By taking advantage of the field amplification properties of soft-iron, a considerable amount of power can be saved. In this work, an optimized selection and focus field generator is presented, that can generate flexible and high gradient fields at comparatively lowpower consumption. Coil spacing and possible field-free-point positions are similar to conventional MPI scanners designed with air coils,...

Rogue waves: from nonlinear Schrödinger breather solutions to sea-keeping test

Miguel Onorato, Davide Proment, Günther F. Clauss & Marco Klein
Under suitable assumptions, the nonlinear dynamics of surface gravity waves can be modeled by the one-dimensional nonlinear Schrödinger equation. Besides traveling wave solutions like solitons, this model admits also breather solutions that are now considered as prototypes of rogue waves in ocean. We propose a novel technique to study the interaction between waves and ships/structures during extreme ocean conditions using such breather solutions. In particular, we discuss a state of the art sea-keeping test in...

DEM-based approach for the modeling of gelation and its application to alginate

Philipp Nicolas Depta, Pavel Gurikov, Baldur Schroeter, Attila Forgács, József Kalmár, Geo Paul, Leonardo Marchese, Stefan Heinrich & Maksym Dosta
The gelation of biopolymers is of great interest in the material science community and has gained increasing relevance in the past few decades, especially in the context of aerogels lightweight open nanoporous materials. Understanding the underlying gel structure and influence of process parameters is of great importance to predict material properties such as mechanical strength. In order to improve understanding of the gelation mechanism in aqueous solution, this work presents a novel approach based on...

Combining multi-criteria decision analysis with GIS approaches for decentralized organic wastes composting plants site selection in Tiassalé, Southern Côte d’Ivoire

Dotanhan Yeo, Kouassi Dongo, Eliachie Larissa Eméline Angoua, Adeline Mertenat, Phillipp Lüssenhop, Christian Zurbrügg & Ina Körner
In recent years, decentralized composting appeared as one of the most appropriate treatment options for organic waste valorization in low- and middle-income countries. In Cote d’Ivoire, a pilot project has proved the feasibility of organic municipal solid waste composting for the city of Tiassalé. However, numerous issues still need to be addressed for the establishment of a sustainable decentralized composting system in this city. One of the key issues is site selection. Until now, there...

Convergence results for some piecewise linear solvers

Manuel Radons & Siegfried M. Rump
Let A be a real n× n matrix and z, b∈ Rn. The piecewise linear equation system z- A| z| = b is called an absolute value equation. In this note we consider two solvers for uniquely solvable instances of the latter problem, one direct, one semi-iterative. We slightly extend the existing correctness, resp. convergence, results for the latter algorithms and provide numerical tests.

CONSERVE: A framework for the selection of techniques for monitoring containers security

Rodi Jolak, Thomas Rosenstatter, Mazen Mohamad, Kim Strandberg, Behrooz Sangchoolie, Nasser Nowdehi & Riccardo Scandariato
Context: Container-based virtualization is gaining popularity in different domains, as it supports continuous development and improves the efficiency and reliability of run-time environments. Problem: Different techniques are proposed for monitoring the security of containers. However, there are no guidelines supporting the selection of suitable techniques for the tasks at hand. Objective: We aim to support the selection and design of techniques for monitoring container-based virtualization environments. Approach:: First, we review the literature and identify techniques...

Accelerating the distance-minimizing method for data-driven elasticity with adaptive hyperparameters

Lu Trong Khiem Nguyen, Roland C. Aydin & Christian J. Cyron
Data-driven constitutive modeling in continuum mechanics assumes that abundant material data are available and can effectively replace the constitutive law. To this end, Kirchdoerfer and Ortiz proposed an approach, which is often referred to as the distance-minimizing method. This method contains hyperparameters whose role remains poorly understood to date. Herein, we demonstrate that choosing these hyperparameters equal to the tangent of the constitutive manifold underlying the available material data can substantially reduce the computational cost...

Finite element analysis of class II mandibular unilateral distal extension partial dentures

Laith Abed Sabri, Jwan F. Abdulkareem, Kareem N. Salloomi, Suza A. Faraj, Abdulsalam R. Al-Zahawi, Oday Ibraheem Abdullah & Ibrahim Tulunoglu
The current paper aims to investigate the stress distribution developed in Kennedy Class II mandibular distal extension removable partial dentures due to applying a unilateral load condition in both vertical and lateral oblique directions. 3D models of mandible bone and RPD framework were first built based on actual patient data and later exported to ANSYS software to implement the numerical analysis. For realistic analysis, the model considered the frictional contact between the RPD retainers with...

Influence of acetabular cup thickness on seating and primary stability in total hip arthroplasty

Miriam Ruhr, Johanna Bätz, Klaus Püschel & Michael Morlock
Insufficient primary stability of acetabular hip cups is a complication resulting in early cup loosening. Available cup designs vary in terms of wall thickness, potentially affecting implant fixation. This study investigated the influence of different wall thicknesses on the implantation process and the resulting primary stability using excised human acetabula. Implantations were performed using a powered impaction device providing consistent energy with each stroke. Two different wall thicknesses were compared in terms of seating progress,...

Control of redox potential in a novel continuous bioelectrochemical system led to remarkable metabolic and energetic responses of Clostridium pasteurianum grown on glycerol

Philipp Arbter, Niklas Widderich, Tyll Utesch, Yaeseong Hong & An-Ping Zeng
BACKGROUND: Electro-fermentation (EF) is an emerging tool for bioprocess intensification. Benefits are especially expected for bioprocesses in which the cells are enabled to exchange electrons with electrode surfaces directly. It has also been demonstrated that the use of electrical energy in BES can increase bioprocess performance by indirect secondary effects. In this case, the electricity is used to alter process parameters and indirectly activate desired pathways. In many bioprocesses, oxidation-reduction potential (ORP) is a crucial...

Spin‐ and Stress‐Depending Electrical Transport in Nanoparticle Supercrystals: Sensing Elastic Properties of Organic Tunnel Barriers via Tunneling Magnetoresistance

Axel Dreyer, Thomas Rempel, Martin Gottschalk, Robert Zierold, Agnes Weimer, Artur Feld, Gerold A. Schneider, Horst Weller & Andreas Hütten
Abstract The spin‐dependent electrical transport in rigid inorganic‐inorganic layered systems is extensively applied for the detection of magnetic fields in data storage. In this work, spin‐dependent electrical transport in flexible organic‐inorganic supercrystals based on superparamagnetic iron oxide nanoparticles is investigated. These nanoparticles are stabilized by oleic acid ligands, which in turn are serving as tunneling barriers between individual magnetic nanoparticles. The resulting tunneling magnetoresistance (TMR) is tunable due to the elastic properties of these organic...

A secure and extensible blockchain-based data provenance framework for the Internet of things

Marten Sigwart, Michael Borkowski, Marco Peise, Stefan Schulte & Stefan Tai
As data collected and provided by Internet of Things (IoT) devices power an ever-growing number of applications and services, it is crucial that this data can be trusted. Data provenance solutions combined with blockchain technology are one way to make data more trustworthy by providing tamper-proof information about the origin and history of data records. However, current blockchain-based solutions for data provenance fail to take the heterogeneous nature of IoT applications and their data into...

Periodic hill flow simulations with a parameterized cumulant lattice Boltzmann method

Martin Gehrke & Thomas Rung
The article is concerned with the assessment of a cumulant lattice Boltzmann method in wall-bounded, separated turbulent shear flows. The approach is of interest for its resolution-spanning success in turbulent channel flows without using a specific turbulence treatment. The assessment focuses upon the flow over a periodic hill, which offers a rich basis of numerical and experimental data, for Reynolds numbers within (Formula presented.). The analysis involves the mean flow field, second moments and their...

Variance asymptotics and central limit theory for geometric functionals of Poisson cylinder processes

Carina Betken, Matthias Schulte & Christoph Thäle
This paper deals with the union set of a stationary Poisson process of cylinders in Rn having an (n − m)-dimensional base and an m-dimensional direction space, where m ∈ 0, 1, …, n − 1 and n ≥ 2. The concept simultaneously generalises those of a Boolean model and a Poisson hyperplane or m-flat process. Under very general conditions on the typical cylinder base a Berry-Esseen bound for the volume of the union set...

Coexistence of inverse and direct energy cascades in faraday waves

Raffaele Colombi, Niclas Rohde, Michael Schlüter & Alexandra von Kameke
In nature, turbulent flows exist that are neither simply 2D nor 3D but are forced towards one state or the other by boundary conditions such as varying stratification. Here, we report the first evidence of the co-existence of an inverse and a direct energy cascade in an experimental flow driven by Faraday waves in water. We find that an inverse energy cascade at the fluid surface and a direct energy cascade in the 3D bulk...

Wafer-scale electroactive nanoporous silicon : large and fully reversible electrochemo-mechanical actuation in aqueous electrolytes

Manuel Brinker & Patrick Huber
Nanoporosity in silicon results in interface-dominated mechanics, fluidics, and photonics that are often superior to the ones of the bulk material. However, their active control, for example, by electronic stimuli, is challenging due to the absence of intrinsic piezoelectricity in the base material. Here, for large-scale nanoporous silicon cantilevers wetted by aqueous electrolytes, electrosorption-induced mechanical stress generation of up to 600 kPa that is reversible and adjustable at will by potential variations of ≈1 V...

Production of polylactic acid aerogels via phase separation and supercritical CO2 drying: thermodynamic analysis of the gelation and drying process

Alberto Bueno Morales, Christian Lübbert, Sabine Enders, Gabriele Sadowski & Irina Smirnova
The application range of aerogels, especially in the life-science sector, can be extended by utilizing biocompatible polymers such as polylactic acid (PLA). However, the low glass transition temperature (Tg) of PLA and the challenging gelation techniques limit the application of supercritical CO2 (scCO2) drying and thus the PLA-aerogel production. The aim of this work is to overcome this challenge and to provide a better understanding of the thermodynamics of the process. Therefore, the gelation of...

Microbially promoted calcite precipitation in the pelagic redoxcline: elucidating the formation of the turbid layer

Kerstin Leberecht, Simon Michael Ritter, Christian Jonas Lapp, Lukas Klose, Julian Eschenröder, Christian Scholz, Sebastian Kühnel, Wolfgang Stinnesbeck, Arnulf Kletzin, Margot Isenbeck-Schröter & Johannes Gescher
Large bell-shaped calcite formations called “Hells Bells” were discovered underwater in the stratified cenote El Zapote on the Yucatán Peninsula, Mexico. Together with these extraordinary speleothems, divers found a white, cloudy turbid layer into which some Hells Bells partially extend. Here, we address the central question if the formation of the turbid layer could be based on microbial activity, more specifically, on microbially induced calcite precipitation. Metagenomic and metatranscriptomic profiling of the microbial community in...

What’s important for relationship management? : the mediating roles of relational trust and satisfaction for loyalty of cooperative banks’ customers

Svenja Damberg, Manfred Schwaiger & Christian M. Ringle
Building on the corporate reputation model, this study investigates the drivers of customer-based corporate reputation. We consider two corporate reputation dimensions (i.e., the cognitive dimension competence and the affective dimension likeability, and their effects on customer satisfaction and loyalty). Adapting the model to the banking sector, we theoretically extend this model by reasoning that customer satisfaction and relational trust are mediators of the relationship between the two corporate reputation dimensions and loyalty. Studying a sample...

Procedural synthetic training data generation for AI-based defect detection in industrial surface inspection

Ole Schmedemann, Melvin Baaß, Daniel Schoepflin & Thorsten Schüppstuhl
Supervised machine learning methods are increasingly used for detecting defects in automated visual inspection systems. However, these methods require large quantities of annotated image data of the surface being inspected, including images of defective surfaces. In industrial contexts, it is difficult to collect the latter since acquiring sufficient image data of defective surfaces is costly and time-consuming. Additionally, gathered datasets tend to contain selection-bias, e.g. under representation of certain defect classes, and therefore result in...

Fat quantification in dual-layer detector spectral computed tomography : experimental development and first in-patient validation

Isabel Molwitz, Graeme Michael Campbell, Jin Yamamura, Tobias Knopp, Klaus Tödter, Roland F. Fischer, Zhiyue Jerry Wang, Alina Busch, Ann-Kathrin Ozga, Shuo Zhang, Thomas Lindner, Florian Sevecke, Mirco Grosser, Gerhard Adam & Patryk Szwargulski
Objectives Fat quantification by dual-energy computed tomography (DECT) provides contrast-independent objective results, for example, on hepatic steatosis or muscle quality as parameters of prognostic relevance. To date, fat quantification has only been developed and used for source-based DECT techniques as fast kVp-switching CT or dual-source CT, which require a prospective selection of the dual-energy imaging mode. It was the purpose of this study to develop a material decomposition algorithm for fat quantification in phantoms and...

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