374 Works

Protein engineering and synthetic pathways in Escherichia coli for effective production of 5-hydroxytryptophan and serotonin

José Aníbal Mora Villalobos
Metabolic Engineering hat in den letzten zwei Jahrzehnten erhebliche Verbesserungen der Produktion von Tryptophan in E. coli ermöglicht und somit zahlreiche Möglichkeiten für die Produktion von Tryptophan-Derivaten eröffnet. 5-Hydroxy-tryptophan (5HTP) und Serotonin sind zwei wichtige Beispiele hierfür, welche nicht nur im Hinblick auf ihren pharmazeutischen Wert bedeutend sind, sondern auch als Vorläufer anderer Moleküle dienen können. Hierzu gehören unter anderem Schlafzyklusregulatoren, Antimigräne-Medikamente, Sedativa, Antikonvulsiva, Medikamente zur Tumorbekämpfung, antimikrobielle Mittel, antivirale Mittel und viele weitere mehr....

A nanoporous gold-polypyrrole hybrid nanomaterial for actuation

Ke Wang, Charlotte Stenner & Jörg Weissmüller
We discuss actuation with a hybrid nanomaterial that is made by electro-polymerizing pyrrole on the internal surfaces of dealloying-derived nanoporous gold and then letting aqueous electrolyte be imbibed in the remaining pore space. In this way, active polypyrrole films are contacted by two separate but individually contiguous conduction paths, providing efficient transport of ions in the electrolyte channels and of electrons in the metal skeleton. The metal skeleton also serves to enhance the mechanical behavior...

Interface elasticity effects in polymer-filled nanoporous metals

Jana Wilmers, Andrew McBride & Swantje Bargmann
A continuum formulation for electroactive composites made from nanoporous gold and ionconducting polymer is proposed. A novel extension of surface elasticity theory is developed to account for the high surface-to-volume ratio of nanoporous gold, and to capture the chemoelectromechanical coupling that occurs on the interface between the metal and the polymer. This continuum formulation accounts for the fully non-linear behaviour exhibited by the composite. The balance of linear momentum, Gauß's flux theorem and a relation...

Identification and control of the laser-based synchronization system for the European X-ray Free Electron Laser

Michael Heuer
(wird nachgereicht)

Fabrication of composites via spouted bed granulation process and simulation of their micromechanical properties

Eduard Eichner, Maksym Dosta, Stefan Heinrich & Gerold A. Schneider
In this contribution numerical simulation of Young’s modulus of copper-polymer composites is presented. For the simulation of the composites the Bonded-Particle-Model was applied. The model allows representing of the structure of composite materials realistically. The polymer matrix, which surrounds the particles, was represented as network of solid bonds connecting copper particles. Simulation results were validated based on mechanical determination of modulus of elasticity. The modulus of elasticity was approximated in experiments as well as in...

Exploring the acceptance of ubiquitous computing-based Information services in brick and mortar retail environments - an integration of UTAUT2 and media system dependency theory

Sara Kheiravar
Stationäre Einzelhändler setzen zunehmend digitale Technologie ein, um ihren Kunden bei Informationssuche und -bewertung zu unterstützen. Die eingesetzten Technologien werden als In-Store Ubiquitous Computing basierende Informationstechnologien bezeichnet. Erkenntnisse zu Akzeptanz dieser Technologien durch Kunden stehen noch aus. In dieser Dissertation wird ein Kontext spezifisches Modell zur Technologieakzeptanz basierend auf UTAUT2 entwickelt und um Nutzer, Service und Technologie relevante Aspekte erweitert. Das abgeleitete Modell wird mit Hilfe eines Strukturgleichungsmodells (PLS) auf Basis einer auf Szenarien basierenden...

Performance evaluation of small sized powdered ferric hydroxide as arsenic adsorbent

Muhammad Usman, Ioannis A. Katsoyiannis, Manassis Mitrakas, Anastasios I. Zouboulis & Mathias Ernst
The small sized powdered ferric oxy-hydroxide, termed Dust Ferric Hydroxide (DFH), was applied in batch adsorption experiments to remove arsenic species from water. The DFH was characterized in terms of zero point charge, zeta potential, surface charge density, particle size and moisture content. Batch adsorption isotherm experiments indicated that the Freundlich model described the isothermal adsorption behavior of arsenic species notably well. The results indicated that the adsorption capacity of DFH in deionized ultrapure water,...

Synthesis of uniform bulk nanoporous palladium with tunable structure

Shan Shi, Jürgen Markmann & Jörg Weissmüller
This work presents systematic investigations on the synthesis of hierarchical nanoporous Pd via electrochemical dealloying of CuPd alloys in sulfuric acid. The impact of electrode potential, dealloying temperature, and additional annealing on microstructure and morphology is explored. Dealloying Cu85Pd15 in 1M sulfuric acid at elevated temperature provides a facile strategy to produce bulk nanoporous Pd samples which are uniform, hierarchically nanoporous, and free of macro-scale cracks. The question “Why will one-step template-free dealloying yield a...

What pathways lead to frugal innovation? : Some insights on modes & routines of frugal, technical inventions based on an analysis of patent data in German auto components industry

Rajnish Tiwari & Stephan Bergmann
Frugal innovations, i.e. affordable products and services with appropriately good quality, are getting increasingly important for securing long-term competitiveness in both, the developing world and in industry nations. Nevertheless, ensuring actual implementation of technology-driven frugal inventions remains an under-researched area. This study investigates modes and routines employed by techno-entrepreneurs from industry nations when innovating frugally. The study is based on the patent data of seven auto component sector firms from Germany with a documented history...

Electro-conductive composite gold-polyethersulfone-ultrafiltration-membrane : characterization of membrane and natural organic matter (NOM) filtration performance at different in-stiu applied surface potentials

Tomi Mantel, Paul Benne, Stanislav Parsin & Mathias Ernst
Next to the pore size distribution, surface charge is considered to be one main factor in the separation performance of ultrafiltration (UF) membranes. By applying an external surface potential onto an electro-conductive UF membrane, electrostatic induced rejection was investigated. This study introduces in a first part a relatively simple but yet not reported technology of membrane modification with direct current sputter deposition of ultrathin (15 nm) highly conductive gold layers. In a second part, characterization...

Compiler-based extraction of event arrival functions for real-time systems analysis

Dominic Oehlert, Selma Saidi & Heiko Falk
Event arrival functions are commonly required in real-time systems analysis. Yet, event arrival functions are often either modeled based on specifications or generated by using potentially unsafe captured traces. To overcome this shortcoming, we present a compiler-based approach to safely extract event arrival functions. The extraction takes place at the code-level considering a complete coverage of all possible paths in the program and resulting in a cycle accurate event arrival curve. In order to reduce...

The influence of pressure on crude oil biodegradation in shallow and deep Gulf of Mexico sediments

Uyen T. Nguyen, Sara A. Lincoln, Ana Gabriela Valladares Juárez, Martina Schedler, Jennifer L. Macalady, Rudolf Müller & Katherine H. Freeman
A significant portion of oil released during the Deepwater Horizon disaster reached the Gulf of Mexico (GOM) seafloor. Predicting the long-term fate of this oil is hindered by a lack of data about the combined influences of pressure, temperature, and sediment composition on microbial hydrocarbon remineralization in deep-sea sediments. To investigate crude oil biodegradation by native GOM microbial communities, we incubated core-top sediments from 13 GOM sites at water depths from 60-1500 m with crude...

Jahresbericht des Präsidiums 2017

& Garabed Antranikian
Jahresbericht des Präsidiums der TU Hamburg 2017

An analytical model for wireless mesh networks with collision-free TDMA and finite queues

Florian Kauer & Volker Turau
Wireless mesh networks are a promising technology for connecting sensors and actuators with high flexibility and low investment costs. In industrial applications, however, reliability is essential. Therefore, two time-slotted medium access methods, DSME and TSCH, were added to the IEEE 802.15.4 standard. They allow collision-free communication in multi-hop networks and provide channel hopping for mitigating external interferences. The slot schedule used in these networks is of high importance for the network performance. This paper supports...

Analysis of the influence of imaging-related uncertainties on cerebral aneurysm deformation quantification using a no-deformation physical flow phantom

Daniel Schetelig, Jan Sedlacik, Jens Fiehler, Andreas M. J. Frölich, Tobias Knopp, Thilo Sothmann, Jonathan Waschkewitz & René Werner
Cardiac-cycle related pulsatile aneurysm motion and deformation is assumed to provide valuable information for assessing cerebral aneurysm rupture risk. Accordingly, numerous studies addressed quantification of cerebral aneurysm wall motion and deformation. Most of them utilized in vivo imaging data, but image-based aneurysm deformation quantification is subject to pronounced uncertainties: unknown ground-truth deformation; image resolution in the order of the expected deformation; direct interplay between contrast agent inflow and image intensity. To analyze the impact of...

Hierarchical aerographite 3D flexible networks hybridized by InP micro/nanostructures for strain sensor applications

Irina Plesco, Julian Strobel, Fabian Schütt, Cameliu Constantin Himcinschi, Nabiha Ben Sedrine, Teresa Monteiro, Maria Rosário Correia, Leonid Gorceac, Boris Cinic, Veaceslav Ursaki, Janik Marx, Bodo Fiedler, Yogendra Kumar Mishra, Lorenz Kienle, Rainer Adelung & Ion Tiginyanu
In the present work, we report on development of three-dimensional flexible architectures consisting of an extremely porous three-dimensional Aerographite (AG) backbone decorated by InP micro/nanocrystallites grown by a single step hydride vapor phase epitaxy process. The systematic investigation of the hybrid materials by scanning electron microscopy demonstrates a rather uniform spatial distribution of InP crystallites without agglomeration on the surface of Aerographite microtubular structures. X-ray diffraction, transmission electron microscopy and Raman scattering analysis demonstrate that...

Extension of multi-commodity closed-loop supply chain network design by aggregate production planning

Leena Steinke & Kathrin Fischer
In this work the influence of production and capacity planning on decisions regarding facility location, distribution quantities and component remanufacturing (and vice versa) in a closed-loop supply chain network (CLSCN) with multiple make-to-order products is studied. A mathematical model, the facility location, capacity and aggregate production planning with remanufacturing (FLCAPPR) model, for designing the CLSCN, for planning capacities at the facilities and for structuring the production and distribution system of the network cost-optimally, is formulated....

Restarting iterative projection methods for Hermitian nonlinear eigenvalue problems with minmax property

Marta Betcke & Heinrich Voß
In this work we present a new restart technique for iterative projection methods for nonlinear eigenvalue problems admitting minmax characterization of their eigenvalues. Our technique makes use of the minmax induced local enumeration of the eigenvalues in the inner iteration. In contrast to global numbering which requires including all the previously computed eigenvectors in the search subspace, the proposed local numbering only requires a presence of one eigenvector in the search subspace. This effectively eliminates...

The road to a digitalized supply chain management: smart and digital solutions for supply chain management

Wolfgang Kersten, Thorsten Blecker & Christian M. Ringle
This volume contains research contributions by an international group of authors addressing innovative and technology-based approaches for logistics and supply chains. They present business models and investment options for enhanced strategic decision making as well as recent approaches for supply chain analytics and risk management. This volume, edited by Wolfgang Kersten, Thorsten Blecker and Christian Ringle, provides valuable insights into the digitalization of Supply Chain Management and Logistics with regard to: Innovation and Technology Management,...

Scope for Industry 4.0 in Agri-food Supply Chain

Claudine Soosay & Raja Kannusamy
This study investigates the current capabilities and technologies adopted in the agri-food industry in Australia and the scope for transition to Industry 4.0. Data were collected from 360 firms representing suppliers, producers, manufacturers, wholesalers, logistics providers and retailers to represent a supply chain perspective. The technologies and strategies were grouped based on the various supply chain players against the maturity stages of Industry 4.0 as prescribed by Schuh et al (2017) in order to discern...

Meta-Analysis of Sustainable Transport Logistics Trends

Johannes Dirnberger & Uwe Brunner
In general, Austrian manufacturing companies need to catch up in terms of sustainable transport logistics. Awareness-raising on sustainability and a broad debate are necessary that companies rethink in this context. This paper, therefore, develops and applies a meta-analysis in order to analyze the development of transport logistics trends. This research integrates qualitative and quantitative elements of the content analysis. Firstly, existing trend analyses are evaluated and compared in order to subsequently define trend categories. Secondly,...

Influence of drayage patterns on truck appointment systems

Ann-Kathrin Lange, Kristof Ole Kühl, Anne Kathrina Schwientek & Carlos Jahn
Truck appointment systems (TAS) are a well-recognized method to smooth the peaks in truck arrivals at seaport container terminals and thereby reduce operation costs for the terminals and waiting times for trucking companies. This study analyzes the influence of different drayage patterns on the success of a TAS at seaport container terminals by means of a discrete event simulation model. These drayage patterns vary in the percentages of transports between container terminals and container terminals...

Clinical and wear analyses of 9 large metal-on-metal total hip prostheses

Maarten C. Koper, Nina M. C. Mathijssen, Florian Witt, Michael Morlock & Stephan B. W. Vehmeijer
Metal-on-Metal (MoM) total hip arthroplasties (THA) are associated with pseudotumor formation and high revision rates. This prospective study analysed the clinical and wear analyses of 9 large Metal-on-Metal (MoM) total hip arthroplasties (THA) to understand the underlying mechanisms of failure. The MoM bearings were revised for multiple reasons; the main reason was pseudotumor formation.

Membrane-type acoustic metamaterials for aircraft noise shields

Felix Langfeldt
In der Arbeit werden akustische Membran-Metamaterialien auf ihre Anwendbarkeit zur effizienten Reduktion von tieffrequenten Tönen untersucht. Es werden analytische Modelle zur Berechnung der Schalldämmung von Schallschutzmaßnahmen mit Membran-Metamaterialien entwickelt. Diese Modelle werden verwendet, um ein Schallschutzschild für einen Flugzeugrumpf zu entwerfen. Die experimentelle Charakterisierung des Schallschutzschildmodells erfolgt unter realitätsähnlichen Einbau- und Anregungsbedingungen an einer Flugzeugrumpfteststruktur.

Development and validation of a procedure for numerical vibration analysis of an oscillating wave surge converter

Pál Schmitt, Christian Windt, Jonathan Nicholson & Björn Elsäßer
During extreme sea states so called impact events can be observed on the wave energy converter Oyster. In small scale experimental tests these impact events cause high frequency signals in the measured load which decrease confidence in the data obtained. These loads depend on the structural dynamics of the model. Amplification of the loads can occur and is transferred through the structure from the point of impact to the load cell located in the foundation....

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