275 Works

Wie digital ist Informationskompetenz? : Materialien zu einem Workshop

Thomas Hapke
Workshop am 5. Februar 2016 auf dem Kunst- und Mediencampus Finkenau der Hochschule für Angewandte Wissenschaften Hamburg (Folien, Reader, Ergebnisse) im Rahmen der Move and Make – in/trans/formation durch Themen, Trends und Visionen - Fachtagung des Department Information der HAW Hamburg anlässlich 70 Jahre bibliothekarische Ausbildung für öffentliche und wissenschaftliche Bibliotheken in Hamburg und 45 Jahre Fachbereich Bibliothek und Information an der Hochschule für Angewandte Wissenschaften (http://intransformation.hamburg/).

Das Jubiläums-Stichwort „in/trans/formation“ zu 70 Jahren BibliothekarischeThomas...

Near-field radiative heat transfer with hyperbolic metamaterials

Slawa Lang
Max Plancks bedeutende Schwarzkörper Theorie kann den Anstieg der strahlenden Wärmeübertragung zwischen eng aneinanderliegenden Körpern, bekannt als Nahfeld Wärmeübertragung, nicht erklären. Wir demonstrieren diesen Effekt mit Hilfe einer neuen, dynamischen Messmethode und messen Wärmeströme bis zu 16-mal größer als die Schwarzkörper Grenze. Wir zeigen, dass thermische Strahlung in hyperbolischen Metamaterialien (HMMs) – äußerst anisotropen Nanostrukturen – sehr stark ist und ihre Eigenschaften sich von Schwarzkörper Strahlung deutlich unterscheiden. Schließlich erweisen sich Nahfeld Wärmeströme zwischen HMMs...

Optimization of solvent-free enzymatic esterification in eutectic substrate reaction mixture

Magdalena Pätzold, Anna Weimer, Andreas Liese & Dirk Holtmann
The Candida rugosa lipase catalyzed esterification of (-)-menthol and lauric acid (LA) was studied in a eutectic mixture formed by both substrates((-)-menthol:LA 3:1, mol/mol). No additional reaction solvent was necessary, since the (-)-menthol:LA deep eutectic solvent (DES) acts as combined reaction medium and substrate pool. Therefore, the esterification is conducted under solvent-free conditions. The thermodynamic water activity (aw) was identified as a key parameter affecting the esterification performance in the (-)-menthol:LA DES. A response surface...

Influence of oxygen vacancies on two-dimensional electron systems at SrTiO3-based interfaces and surfaces

Michael Sing, Harald O. Jeschke, Frank Lechermann, Roser Valentí & Ralph Claessen
The insulator SrTiO3 can host high-mobility two-dimensional electron systems on its surfaces and at interfaces with other oxides. While for the bare surface a two-dimensional electron system can only be induced by oxygen vacancies, it is believed that the metallicity of heterostructure interfaces as in LaAlO3/SrTiO3 is caused by other mechanisms related to the polar discontinuity at the interface. Based on calculations using density functional and dynamical mean-field theory as well as on experimental results...

Using tutorials in introductory physics on circuits in a German university course: observations and experiences

Peter Riegler, Andreas Simon, Marcus Prochaska, Christian H. Kautz, Rebekka Bierwirth, Susan Hagendorf & Gerd Kortemeyer
We describe the implementation of Tutorials in Introductory Physics in a German university course. In particular, we investigate if the conceptual challenges that gave rise to the development of Tutorials are also found among German students, which hurdles to the implementation of Tutorials are encountered in a German context, and how Tutorials are perceived in this different context. To that end, video recordings from workgroup sessions and guided group discussions with students and teaching assistants,...

A genome-wide study of two-component signal transduction systems in eight newly sequenced mutans streptococci strains

Lifu Song, Padhmanand Sudhakar, Wei Wang, Georg Conrads, Anke Brock, Jibin Sun, Irene Wagner-Döbler & An-Ping Zeng
Mutans streptococci are a group of gram-positive bacteria including the primary cariogenic dental pathogen Streptococcus mutans and closely related species. Two component systems (TCSs) composed of a signal sensing histidine kinase (HK) and a response regulator (RR) play key roles in pathogenicity, but have not been comparatively studied for these oral bacterial pathogens.

Steuerung der Reaktionsselektivität der biokatalytischen Fettsäureestersynthese

Sören Baum
Eine industrielle Herausforderung für die lösungsmittelfreie Synthese von hochreinem Mono oder –diacylglyceride (MAG´s & DAG´s) ist das dem Reaktionssystems innewohnende Phasenverhalten und die daraus resultierenden geringen Reaktionsselektivitäten. In der vorliegenden Dissertation konnte durch geringe Mengen des amphoteren Tensids Cocoamidpropyl Betain in einer lösungsmittelfreien Biokatalyse eine Steigerung der Selektivität hinzu MAG’s sowie die Löslichkeit von Glycerol in der unpolaren Reaktionsphase gezeigt werden und somit wurden gleiche MAG Gleichgewichtsanteile erreicht wie unter Einsatz des Lösungsmittels tert-Butanol. Eine...

M03.005 Qualitative and quantitative determination of saponins by LC-MSTOF and LC-MS/MS

Alina Stahl & Heike Frerichs
Mit der vorliegenden Methode können die Ginsenoside Panaxatriol, Panaxadiol, Rb1, Rd, Rg3, Rh2, Compound K und F2, sowie die beiden Sojasaponine Aa und Bb in enzymatisch behandelten Soja- oder Ginsengextrakten quantitativ erfasst werden. Die quantitative Messung verschiedener Saponine (aktuell z.B. Rg1, Rb1, Panaxatriol und Panaxadiol) erfolgt mittels LC-MSMS (Sciex Qtrap 5500) mit einer Luna C18-Säule in positiver und negativer Polarität (gleichzeitig). Die Auswertung erfolgt über eine externe Kalibrierung mit Integration der Peakfläche. Sollen andere Saponin-Abbauprodukte...

Damage tolerance of refill friction stir spot weld application for the aircraft industry

Robson Cristiano Brzostek
Refill Friction Stir Spot Welding (Refill FSSW) is a solid-state process technology that is suitable for welding lightweight materials in similar or dissimilar overlapped configuration. It has proven to be a very promising new joining technique; especially, for high strength aluminum alloys, which has presented large advantages when compared to conventional welding processes. Currently, Refill FSSW is recognized as a potential alternative for riveted structure; it allows an increasing of the manufacturing cost effectiveness owing...

Real time pose control of an industrial robotic system for machining of large scale components in aerospace industry using laser tracker system

Christian Moeller, Hans Christian Schmidt, Philip Koch, Christian Boehlmann, Simon Kothe, Jörg Wollnack & Wolfgang Hintze
Copyright © 2017 SAE International. The high demand of efficient large scale machining operations by concurrently decreasing operating time and costs has led to an increasing usage of industrial robots in contrast to large scaled machining centers. The main disadvantage of industrial robots used for machining processes is their poor absolute accuracy, caused by the serial construction, resilience of gearings and sensitivity for temperature changes. Additionally high process forces that occur during machining of CFRP...

Yttria-stabilized zirconia microspheres: Novel building blocks for high-temperature photonics

Elisabeth W. Leib, Robert M. Pasquarelli, Jefferson Jean Do Rosário, Pavel N. Dyachenko, Sebastian Döring, Anke Puchert, Alexander Petrov, Manfred Eich, Gerold A. Schneider, Rolf Janßen, Horst Weller & Tobias Vossmeyer
Zirconia-based ceramics cover a huge variety of applications, including refractories, electro- and bioceramics, fuel cells, catalysts, and many more. For various photonic applications considered for energy systems and heat management, zirconia microspheres are interesting building blocks due to their high refractive index, as well as their chemical and mechanical robustness. However, instabilities caused by thermally-induced phase transitions and grain growth at temperatures above ∼1000 °C preclude high-temperature applications of pure zirconia particles. Here, we present...

Bioimpedance analysis of L929 and HaCaT cells in low frequency range

Viviane S. Teixeira, Jan-Patrick Kalckhoff, Wolfgang Krautschneider & Dietmar Schröder
In this work, Bioimpedance Spectroscopy (BIS) is used to study fuids and cell solutions. A new four-electrode-terminal (4T) chamber using 3D printing and stainless steel corrosion resistant V4A was designed to measure the impedance of live cell solutions at the frequency range 0.1Hz-1MHz. At f < 1kHz the double layer (DL) that builds at electrode's surface raises the impedance substantially preventing the observation of the real impedance of the cells. The new 4T design circumvents...

Effect of cavity preparation and bone mineral density on bone-interface densification and bone-implant contact during press-fit implantation of hip stems

Johanna Bätz, Philipp Messer-Hannemann, Frank Lampe, Anke Klein, Klaus Püschel, Michael Morlock & Graeme Michael Campbell
Implant loosening and periprosthetic fracture are two major revision causes for uncemented hip stems. The chosen method of cavity preparation could play a key role for both failure mechanisms. The aim of this study was to determine the dependence of the broach type as well as patient bone mineral density (BMD) on densification and contact conditions at the bone-implant interface. Hip stems were implanted into cadaveric femora using compaction, blunt extraction or sharp extraction broaches...

Hierarchical supercrystalline nanocomposites through the self-assembly of organically-modified ceramic nanoparticles

Berta Domènech Garcia, Michael Kampferbeck, Emanuel Larsson, Tobias Krekeler, Büsra Bor, Diletta Giuntini, Malte Blankenburg, Martin Ritter, Martin Müller, Tobias Vossmeyer, Horst Weller & Gerold Schneider
Biomaterials often display outstanding combinations of mechanical properties thanks to their hierarchical structuring, which occurs through a dynamically and biologically controlled growth and self-assembly of their main constituents, typically mineral and protein. However, it is still challenging to obtain this ordered multiscale structural organization in synthetic 3D-nanocomposite materials. Herein, we report a new bottom-up approach for the synthesis of macroscale hierarchical nanocomposite materials in a single step. By controlling the content of organic phase during...

Machining of large scaled CFRP-parts with mobile CNC-based robotic system in aerospace industry

Christian Möller, Hans Christian Schmidt, Philip Koch, Christian Böhlmann, Simon M. Kothe, Jörg Wollnack & Wolfgang Hintze
Industrial robots have already demonstrated their advantages in smart and efficient production in a wide field of applications and industries. However, their use for machining of structural aircraft components is still impeded by the disadvantage of low absolute accuracy, sensitivity to process loads and limited workspace compared to large machining centers. A mobile robotic system is presented as a new approach for machining applications of large aircraft components. The system presented in this paper consists...

Measurement of local crystal lattice strain variations in dealloyed nanoporous gold

Christoph Mahr, Knut Müller-Caspary, Matthias Graf, Anastasia Lackmann, Tim Grieb, Marco Schowalter, Florian Fritz Krause, Thorsten Mehrtens, Arne Wittstock, Jörg Weißmüller & Andreas Rosenauer
Reversible macroscopic length changes in nanoporous structures can be achieved by applying electric potentials or by exposing them to different gases or liquids. Thus, these materials are interesting candidates for applications as sensors or actuators. Macroscopic length changes originate from microscopic changes of crystal lattice parameters. In this report, we show spatially resolved measurements of crystal lattice strain in dealloyed nanoporous gold. The results confirm theory by indicating a compression of the lattice along the...

Design, dynamics, and control of micro underwater vehicle systems for autonomous environmental exploration

Eugen Solowjow
This dissertation covers exploration and monitoring of environmental fields with micro underwater vehicles (μAUVs). The design of an underactuated μAUV is presented. Moreover, control concepts are introduced for trajectory tracking and path following. Two methods for underwater self-localization are presented, which are suitable for μAUVs. The first approach is based on time delays of arrival of acoustic signals. The second approach exploits attenuation of electro-magnetic signals in water. Lastly, an information theoretic control method is...

Querkrafttragverhalten von Stahlbeton-Fahrbahnplatten

Lukas Henze
The present work deals with the load-bearing behavior of reinforced concrete slabs. The focus is on the load transfer of concentrated single or block loads, as they occur in bridge structures in the form of wheel loads. However, the findings can also easily be applied to general cases of concentrated block loads on reinforced concrete slabs. In the previous research work on the bearing capacity in shear of reinforced concrete roadway slabs it could be...

Quantum information theory for engineers: free climbing through physics and probability

Christian Jansson
The aim of this supplement to my lecture notes ''Quantum Information Theory for Engineers: An Interpretative Approach`` is to develop a probabilistic framework that can be applied to classical stochastic problems as well as to quantum mechanical problems with interference phenomena. In particular, many paradoxes in quantum theory are demystified. Our approach replaces spacetime by a trinity of time, namely future, present, and past leading to a distinction between outcomes, possibilities, and internal possibilities. Our...

Biomechanical evaluation of location and mode of failure in three screw fixations for a comminuted transforaminal sacral fracture model

Brett D. Crist, Ferris M. Pfeiffer, Michael S. Khazzam, Rebecca A. Kueny, Gregory J. Della Rocca & William L. Carson
Background: Pelvic ringecomminuted transforaminal sacral fracture injuries are rotationally and vertically unstable and have a high rate of failure. Objective: Our study purpose was to use three-dimensional (3D) optical tracking to detect onset location of boneeimplant interface failure and measure the distances and angles between screws and line of applied force for correlation to strength of pelvic fracture fixation techniques. Methods: 3D relative motion across sacralerami fractures and screws relative to bone was measured with...

Update on the impact of type 2 diabetes mellitus on bone metabolism and material properties

Ann-Kristin Picke, Graeme Michael Campbell, Nicola Napoli, Lorenz C. Hofbauer & Martina Rauner
The prevalence of type 2 diabetes mellitus (T2DM) is increasing worldwide, especially as a result of our aging society, high caloric intake and sedentary lifestyle. Besides the well-known complications of T2DM on the cardiovascular system, the eyes, kidneys and nerves, bone strength is also impaired in diabetic patients. Patients with T2DM have a 40–70% increased risk for fractures, despite having a normal to increased bone mineral density, suggesting that other factors besides bone quantity must...

Elektrische, piezoresistive und thermische Charakterisierung der Kohlenstoffstruktur "Aerographit" und deren Epoxidkomposite

Svenja Garlof
Due to their great potential for applications in energy storage, sensor technology or optics, three-dimensionally structured carbon materials and their polymer composites are increasingly the subject of current research. One of these carbon structures - Aerographite - is treated in this dissertation. The aim of this thesis is a comprehensive characterization of Aerographite with regard to mechanical, electrical and thermal properties. These are discussed for the pristine Aerographite and for its epoxy composites. The interpenetrating...

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