498 Works

Advancing the fabrication of YSZ-inverse photonic glasses for broadband omnidirectional reflector films

Jefferson Jean Do Rosário, Quynh Yen Häntsch, Robert M. Pasquarelli, Pavel N. Dyachenko, Eleonora Vriend, Alexander Petrov, Kaline P. Furlan, Manfred Eich & Gerold A. Schneider
A single-step and all-colloidal deposition method to fabricate yttrium-stabilized zirconia (YSZ)-inverse photonic glasses with 3 μm pores was developed. The process is based on electrostatic attraction and repulsion in suspension, controlled by surface charge of polystyrene (PS)microspheres and YSZ nanoparticles, used as pore templates and matrix material, respectively. The pH was used as a tool to change surface charges and particle-particle interactions. Photonic glass films with 3 μm pores yielded broadband omnidirectional reflection over the...

Compilation for real-time systems : an overview of the WCET-aware C compiler WCC

Dominic Paul Oehlert, Arno Luppold & Heiko Falk
Traditionell finden Design und zeitliche Analyse eines eingebetteten harten Echtzeitsystems getrennt voneinander statt. Dies führt zu einem komplexen Designfluss, der menschliche Interaktion benötigt. Weiter optimieren Standardcompiler in Bezug auf die durchschnittliche Performanz, so dass der Systemdesigner nicht bei der Optimierung hinsichtlich der schlimmstmöglichen Programmlaufzeit unterstützt wird. Der WCET-Aware C Compiler WCC verbessert diese Situation, indem Planbarkeitsanalysen eng in den Compilierungs- und Optimierungsprozess mit eingebuden werden. Weiter bietet der Compiler gezielte Möglichkeiten um echtzeitbewusst Optimierungen durchzuführen...

Human-sized magnetic particle imaging for brain applications

Matthias Gräser, Florian Thieben, Patryk Szwargulski, Franziska Werner, Nadine Gdaniec, Marija Boberg, Florian Griese, Martin Möddel, Peter Ludewig, Dionys van de Ven, Oliver M. Weber, Oliver Woywode, Bernhard Gleich & Tobias Knopp
Determining the brain perfusion is an important task for diagnosis of vascular diseases such as occlusions and intracerebral haemorrhage. Even after successful diagnosis, there is a high risk of restenosis or rebleeding such that patients need intense attention in the days after treatment. Within this work, we present a diagnostic tomographic imager that allows access to brain perfusion quantitatively in short intervals. The device is based on the magnetic particle imaging technology and is designed...

Directional soliton and breather beams

Amin Chabchoub, Kento Mozumi, Norbert Hoffmann, Alexander V. Babanin, Alessandro Toffoli, James N. Steer, Ton S. van den Bremer, Nail N. Akhmediev, Miguel Onorato & Takuji Waseda
Solitons and breathers are nonlinear modes that exist in a wide range of physical systems. They are fundamental solutions of a number of nonlinear wave evolution equations, including the unidirectional nonlinear Schrödinger equation (NLSE). We report the observation of slanted solitons and breathers propagating at an angle with respect to the direction of propagation of the wave field. As the coherence is diagonal, the scale in the crest direction becomes finite; consequently, beam dynamics form....

Reclaiming biologically pretreated greywater for reuse by photocatalytic oxidation: qualitative study on the removal of trace organics

Holger Gulyas, Carlos F. Liriano Jorge, Margrit Reich & Ralf Otterpohl
This study was carried out for gathering qualitative information about the potential of photocatalytic oxidation for the removal of trace organics (analysed by gas chromatography coupled to mass spectrometry, GC/MS) from biologically pretreated greywater to make it suitable for high quality reuse applications like groundwater recharge. Additionally, fractions of bulk organics (humic substances, building blocks, and low molecular weight organic acids) were quantified by liquid chromatography with organic carbon detection. Biologically pretreated greywater was subjected...

M02.010 Determination of settleable matter

Tanja Millfahrt & Alina Stahl
This method describes the determination of settleable matter by volume in water and waste water (see DIN 38409-9).

Experimental and analytical investigation of cemented tungsten carbide ultra-short pulse laser ablation

Juan Pablo Calderón Urbina, Christian Daniel & Claus Emmelmann
Ultra-short pulse laser processing of hard materials, such as cemented tungsten carbide, requires an accurate and agile experimental and analytical investigation to obtain adequate information and setting parameters to maximize ablation rate. Therefore, this study presents a systematic approach which, first, experimentally searches for the variables with the most significant influence on the objective using a design of experiments method; and second, analyzes by means of existing ablation theory the interaction of the material and...

Overall process analysis and optimisation for CO₂ capture from coal fired power plants based on phase change solvents forming two liquid phases

Ulrich Liebenthal, Diego D. D. Pinto, Juliana G. M.-S. Monteiro, Hallvard F. Svendsen & Alfons Kather
In this work the potential of a novel post-combustion CO₂ capture process is analysed with respect to the integrated overall process. As solvent a blend of two amines (DEEA/MAPA) which forms two liquid phases under CO₂ loading is used. The two phases have distinct physical characteristics. Only the heavy phase, rich in CO₂ loading, is led to the desorber. The novel solvent combination promises very low energy consumption compared to a 30 wt.-% MEA solution....

Biotechnological strategies for the recovery of valuable and critical raw materials from waste electrical and electronic equipment (WEEE) - A review

Arda Işıldar, Eric D. van Hullebusch, Markus Lenz, Gijs Du Laing, Alessandra Marra, Alessandra Cesaro, Sandeep Panda, Ata Akcil, Mehmet Ali Kücüker & Kerstin Kuchta
Critical raw materials (CRMs) are essential in the development of novel high-tech applications. They are essential in sustainable materials and green technologies, including renewable energy, emissionfree electric vehicles and energy-efficient lighting. However, the sustainable supply of CRMs is a major concern. Recycling end-of-life devices is an integral element of the CRMs supply policy of many countries. Waste electrical and electronic equipment (WEEE) is an important secondary source of CRMs. Currently, pyrometallurgical processes are used to...

3D printed nozzles on a silicon fluidic chip

Sven Bohne, Michael Heymann, Henry N. Chapman, Hoc Khiem Trieu & Saša Bajt
Serial femtosecond crystallography is a new method for protein structure determination utilizing intense and destructive X-ray pulses generated by free-electron lasers. The approach requires the means to deliver hydrated protein crystals to a focused X-ray beam and replenish them at the repetition rate of the pulses. A liquid-jet sample delivery system where a gas dynamic virtual nozzle is printed directly on a silicon-glass microfluidic chip using a 2-photon-polymerization 3D printing process is implemented. This allows...

Dealloying progress during nanoporous structure evolution analyzed by In situ resistometry

Eva-Maria Steyskal, Michael Seidl, Matthias Graf & Roland Würschum
The progress of dealloying, an electrochemical synthesis method capable of producing nanoporous structures with bulk outer dimensions, is studied by in situ resistometry. The resistance increases by three orders of magnitude while nanoporous gold or platinum is formed. Simultaneous monitoring of charge flow and electrical resistance increase proves to be an ideal combination for analyzing the etching progress, which in accordance with recent studies can be demonstrated to occur in two steps referred to as...

Quantitative study of H protein lipoylation of the glycine cleavage system and a strategy to increase its activity by co-expression of LplA

Xinyi Zhang, Mei Li, Yingying Xu, Jie Ren & An-Ping Zeng
Glycine cleavage system (GCS) plays a key role in one-carbon (C1) metabolism related to the biosynthesis of a number of key intermediates with significance in both biomedicine and biotechnology. Despite extensive studies of the proteins (H, T, P and L) involved and the reaction mechanisms of this important enzyme complex little quantitative data are available. In this work, we have developed a simple HPLC method for direct analysis and quantification of the apo- and lipoylated...

High-rate nitrification of membrane-filtrated saline landfill leachate using fixed-bed biofilm reactors

Sreenivasan Ramaswami
Alleine durch Umkehrosmose (UO) kann hochammoniumhaltigen Deponiesickerwässer nicht ausreichend behandelt werden. Die mehrstufige Hochdruckmembrananlage (inklusiv UO und Nanofiltration (NF) Verfahren) für die Sickerwasseraufbereitung in Deponie Ihlenberg ergibt sich ein unzureichender Ammoniumrückhalt. In dieser Arbeit wurde die Nitrifikation in belüfteten Festbettreaktoren untersucht, um dieses Problem zu lösen. Mit dem NF-Permeat des UO-Retentats des Rohsickerwassers (mit 16 g/L Cl-, 45 mS/cm) wurden Nitrifikationseffizienzen über 97% bei Volumenbelastungsraten von ca. 1100 g NH4+-N/(m3∙d) bei 25°C erreicht. Basierend der...

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...

Lubrication analyses of cam and flat-faced follower

Hazim U. Jamali, Amjad Al-Hamood, Oday Ibraheem Abdullah, Adolfo Senatore & Josef Schlattmann
The principal factors that affect the characteristics of contact problem between cam and follower vary enormously during the operating cycle of this mechanism. This includes radius of curvature, surface velocities and applied load. It has been found over the last decades that the mechanism operates under an extremely thin film of lubricant. Any practical improvement in the level of film thickness that separates the contacted surfaces represents an essential step towards a satisfactory design of...

Vibro-acoustic and nonlinear analysis of cadavric femoral bone impaction in cavity preparations

Sebastian Oberst, Johanna Bätz, Graeme Michael Campbell, Frank Lampe, Joseph C. S. Lai, Norbert Hoffmann & Michael Morlock
Owing to an ageing population, the impact of unhealthy lifestyle, or simply congenital or gender specific issues (dysplasia), degenerative bone and joint disease (osteoarthritis) at the hip pose an increasing problem in many countries. Osteoarthritis is painful and causes mobility restrictions; amelioration is often only achieved by replacing the complete hip joint in a total hip arthroplasty (THA). Despite significant orthopaedic progress related to THA, the success of the surgical process relies heavily on the...

Iron oxide-based nanostructured ceramics with tailored magnetic and mechanical properties: Development of mechanically robust, bulk superparamagnetic materials

Diletta Giuntini, Elisa Torresani, Kyle T. Chan, Malte Blankenburg, Lucien Saviot, Büsra Bor, Berta Domènech Garcia, Meir Shachar, Martin Müller, Eugene A. Olevsky, Javier E. Garay & Gerold A. Schneider
Nanostructured iron-oxide based materials with tailored mechanical and magnetic behavior are produced in bulk form. By applying ultra-fast heating routines via spark plasma sintering (SPS) to supercrystalline pellets, materials with an enhanced combination of elastic modulus, hardness and saturation magnetization are achieved. Supercrystallinity-namely the arrangement of the constituent nanoparticles into periodic structures-is achieved through self-assembly of the organically-functionalized iron oxide nanoparticles. The optimization of the following SPS regime allows the control of organics' removal, necking,...

Energetic evaluation of different flow sheet modifications of post-combustion CO₂ capture plant at coal and natural gas fired power plant for a generic improved solvent

Sören Ehlers, Volker Roeder, Alfons Kather, Prachi Singh & John Davison
The post-combustion capture (PCC) technology is a promising possibility to reduce CO₂ emissions of fossil fuel fired power plants. One of the main concerns for the PCC is the loss in electric power output. A reduction in efficiency penalty for solvent based PCC can be achieved by improving the solvent properties as well as by improving the process design. There are many different process flow sheet modifications with an improvement in process design reported in...

Comparative analysis and biochemical characterization of two endo-β-1,3-glucanases from the thermophilic bacterium fervidobacterium sp.

Christin Burkhardt, Christian Schäfers, Jörg Claren, Georg Schirrmacher & Garabed Antranikian
Laminarinases exhibit potential in a wide range of industrial applications including the production of biofuels and pharmaceuticals. In this study, we present the genetic and biochemical characteristics of FLamA and FLamB, two laminarinases derived from a metagenomic sample from a hot spring in the Azores. Sequence comparison revealed that both genes had high similarities to genes from Fervidobacterium nodosum Rt17-B1. The two proteins showed sequence similarities of 62% to each other and belong to the...

Low-pressure micro-mechanical re-adaptation device sustainably and effectively improves locomotor recovery from complete spinal cord injury

Veronica Estrada, Julia Krebbers, Christian Voss, Nicole Brazda, Heinrich Blazyca, Jennifer Illgen, Klaus Seide, Christian Jürgens, Jörg Müller, Rudolf Martini, Hoc Khiem Trieu & Hans Werner Müller
Traumatic spinal cord injuries result in impairment or even complete loss of motor, sensory and autonomic functions. Recovery after complete spinal cord injury is very limited even in animal models receiving elaborate combinatorial treatments. Recently, we described an implantable microsystem (microconnector) for low-pressure re-adaption of severed spinal stumps in rat. Here we investigate the long-term structural and functional outcome following microconnector implantation after complete spinal cord transection. Re-adaptation of spinal stumps supports formation of a...

Mass production of highly active NK cells for cancer immunotherapy in a GMP conform perfusion bioreactor

Katharina Bröker, Evgeny Sinelnikov, Dirk Gustavus, Udo Schumacher, Ralf Pörtner, Hans Hoffmeister, Stefan Lüth & Werner Dammermann
NK cells have emerged as promising candidates for cancer immunotherapy, especially due to their ability to fight circulating tumor cells thereby preventing metastases formation. Hence several studies have been performed to generate and expand highly cytotoxic NK cells ex vivo, e.g., by using specific cytokines to upregulate both their proliferation and surface expression of distinct activating receptors. Apart from an enhanced activity, application of NK cells as immunotherapeutic agent further requires sufficient cell numbers and...

A holistic approach for low cost heliostat fields

Andreas Pfahl, Michael Randt, Florian Meier, Martin Zaschke, Chris Geurts & Michael Buselmeier
The AutoR-project takes a holistic approach to reduce the cost of heliostat fields: Wireless control and energy supply enables to use smaller heliostats which need less steel per mirror area (but usually have high wiring cost). A low cost but high efficient drive system is chosen which reduces energy consumption to a minimum amount and leads to low cost for PV cell and energy storage. The usual boundary layer wind tunnels tests for heliostats are...

Looking for a needle in a haystack : how to search for bottom‐up social innovations that solve complex humanitarian problems

Daniel Johannes Kruse, Moritz Göldner, Katrin Eling & Cornelius Herstatt
The worldwide increase in societal challenges is putting pressure on humanitarian organizations to develop sophisticated approaches to leverage social innovations in the humanitarian sector. Since humanitarian problems are complex problems, with the relevant knowledge being hidden, organizational search theory advocates the application of bottom‐up and theory‐guided search processes to identify the social innovations that solve these. Unfortunately, there has been no theoretical attention to understanding which approaches apply in this context. Further, established theory‐guided bottom‐up...

Aufgabenkonzepte für eine bessere Qualität von E-Prüfungen

Dennis Gallaun, Karsten Kruse & Christian Seifert
E-Assessment kann den Prüfungs- und Korrekturaufwand für die Lehrenden drastisch reduzieren. Es sollte aber auch dazu genutzt werden didaktisch anspruchsvolle Aufga-ben zu entwickeln. Im Rahmen von verschiedenen elektronischen Prüfungen in der Mathematik an der Technischen Universität Hamburg schreiben wir adaptive elektroni-sche Aufgaben mit automatischer Korrektur, und auf diesem Poster werden wir Aufga-benkonzepte vorstellen, mit denen sich die Qualität von Prüfungen verbessern lässt. Um insbesondere in großen Gruppen den Trainingsprozess für jede Studierende indivi-duell fair zu...

Mobiles Testcenter für E-Prüfungen

Dennis Gallaun, Karsten Kruse & Christian Seifert
Die Infrastruktur zur Durchführung von elektronischen Prüfungen ist meist stationärer Natur, d.h. sie werden in eigens dafür eingerichteten Räumen auf stationären Geräten durchgeführt. Das Hamburger MINTFIT Projekt [1] beschreitet hier einen anderen Weg und weicht vom Konzept eines stationären Testcenters ab, hin zu einem mobilen. Beim Hamburger MINTFIT Projekt handelt es sich um ein Kooperationsprojekt im Bereich E-Assessment von vier Hamburger Hochschulen und einem Universitätsklinikum, das neben der Erstellung von elektronischen Einstufungstests für das Studium...

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