TY - JOUR A1 - Engelmann, Ulrich M. A1 - Buhl, Eva Miriam A1 - Draack, Sebastian A1 - Viereck, Thilo A1 - Frank, A1 - Schmitz-Rode, Thomas A1 - Slabu, Ioana T1 - Magnetic relaxation of agglomerated and immobilized iron oxide nanoparticles for hyperthermia and imaging applications JF - IEEE Magnetic Letters N2 - Magnetic nanoparticles (MNPs) are used as therapeutic and diagnostic agents for local delivery of heat and image contrast enhancement in diseased tissue. Besides magnetization, the most important parameter that determines their performance for these applications is their magnetic relaxation, which can be affected when MNPs immobilize and agglomerate inside tissues. In this letter, we investigate different MNP agglomeration states for their magnetic relaxation properties under excitation in alternating fields and relate this to their heating efficiency and imaging properties. With focus on magnetic fluid hyperthermia, two different trends in MNP heating efficiency are measured: an increase by up to 23% for agglomerated MNP in suspension and a decrease by up to 28% for mixed states of agglomerated and immobilized MNP, which indicates that immobilization is the dominant effect. The same comparatively moderate effects are obtained for the signal amplitude in magnetic particle spectroscopy. Y1 - 2018 U6 - https://doi.org/10.1109/LMAG.2018.2879034 SN - 1949-307X VL - 9 IS - Article number 8519617 PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Quittmann, Oliver J. A1 - Meskemper, Joshua A1 - Abel, Thomas A1 - Albracht, Kirsten A1 - Foitschik, Tina A1 - Rojas-Vega, Sandra A1 - Strüder, Heiko K. T1 - Kinematics and kinetics of handcycling propulsion at increasing workloads in able-bodied subjects JF - Sports Engineereing N2 - In Paralympic sports, biomechanical optimisation of movements and equipment seems to be promising for improving performance. In handcycling, information about the biomechanics of this sport is mainly provided by case studies. The aim of the current study was (1) to examine changes in handcycling propulsion kinematics and kinetics due to increasing workloads and (2) identify parameters that are associated with peak aerobic performance. Twelve non-disabled male competitive triathletes without handcycling experience voluntarily participated in the study. They performed an initial familiarisation protocol and incremental step test until exhaustion in a recumbent racing handcycle that was attached to an ergometer. During the incremental test, tangential crank kinetics, 3D joint kinematics, blood lactate and ratings of perceived exertion (local and global) were identified. As a performance criterion, the maximal power output during the step test (Pmax) was calculated and correlated with biomechanical parameters. For higher workloads, an increase in crank torque was observed that was even more pronounced in the pull phase than in the push phase. Furthermore, participants showed an increase in shoulder internal rotation and abduction and a decrease in elbow flexion and retroversion. These changes were negatively correlated with performance. At high workloads, it seems that power output is more limited by the transition from pull to push phase than at low workloads. It is suggested that successful athletes demonstrate small alterations of their kinematic profile due to increasing workloads. Future studies should replicate and expand the test spectrum (sprint and continuous loads) as well as use methods like surface electromyography (sEMG) with elite handcyclists. Y1 - 2018 U6 - https://doi.org/10.1007/s12283-018-0269-y SN - 1460-2687 VL - 21 IS - 21 SP - 283 EP - 294 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Michel, Philipp A1 - Butenweg, Christoph A1 - Kinkel, Sven T1 - Pile-grid foundations of onshore wind turbines considering soil-structure-interaction under seismic loading JF - Soil Dynamics and Earthquake Engineering N2 - In recent years, many onshore wind turbines are erected in seismic active regions and on soils with poor load bearing capacity, where pile grids are inevitable to transfer the loads into the ground. In this contribution, a realistic multi pile grid is designed to analyze the dynamics of a wind turbine tower including frequency dependent soil-structure-interaction. It turns out that different foundations on varying soil configurations heavily influence the vibration response. While the vibration amplitude is mostly attenuated, certain unfavorable combinations of structure and soil parameters lead to amplification in the range of the system's natural frequencies. This testifies the need for overall dynamic analysis in the assessment of the dynamic stability and the holistic frequency tuning of the turbines. Y1 - 2018 U6 - https://doi.org/10.1016/j.soildyn.2018.03.009 SN - 0267-7261 VL - 109 SP - 299 EP - 311 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Butenweg, Christoph A1 - Marinkovic, Marko T1 - Erdbebensicherer Anschluss von Ausfachungsmauerwerk in Stahlbetonrahmentragwerken mit Entkopplungselementen JF - Bauingenieur N2 - Stahlbetonrahmentragwerke mit Mauerwerksausfachungen weisen nach Erdbebenereignissen häufig schwere Schäden auf, da die Ausfachungen ohne weitere konstruktive Maßnahmen mit vollem Kontakt zum Stahlbetonrahmen eingemauert werden. Durch die unplanmäßige Beteiligung am horizontalen Lastabtrag erfahren die Ausfachungen Belastungen in Wandebene und beeinflussen das globale Schwingungsverhalten der Rahmentragwerke. In Kombination mit den gleichzeitig auftretenden seismischen Trägheitskräften senkrecht zur Wand führt dies in vielen Fällen zu einem Versagen der mit niedrigen Festigkeiten ausgeführten Ausfachungen. Dies war der Anlass in dem europäischen Forschungsprojekt INSYSME ein Entkopplungssystem zu entwickeln, mit dem Rahmen und Ausfachung durch ein spezielles Profil aus Elastomeren entkoppelt werden. Das Profil ermöglicht Relativverschiebungen zwischen Rahmen und Ausfachung und stellt gleichzeitig die Aufnahme von Belastungen senkrecht zur Wand sicher. Der Beitrag erläutert zunächst den Aufbau des Systems und gibt einen Überblick über die in Kleinbauteilversuchen ermittelten Tragfähigkeiten. Zudem werden experimentelle Untersuchungen an mit hochwärmedämmenden Mauerziegeln ausgefachten Stahlbetonrahmen mit und ohne Entkopplungssystem für getrennte und kombinierte Belastungen in und senkrecht zur Wandebene vorgestellt. Auf Grundlage einer Versuchsauswertung und eines Ergebnisvergleichs werden Wirkungsweise und Effektivität des entwickelten Entkopplungssystems demonstriert. Y1 - 2018 SN - 0005-6650 VL - 93 IS - 9 SP - 333 EP - 341 PB - VDI Fachmedien CY - Düsseldorf ER - TY - JOUR A1 - Rosin, Julia A1 - Butenweg, Christoph A1 - Cacciatore, Pamela A1 - Boesen, Niklas T1 - Investigation of the seismic performance of modern masonry buildings during the Emilia Romagna earthquake series T1 - Untersuchungen des seismischen Verhaltens von modernen Mauerwerksbauten während der Erdbebenserie in der Emilia Romagna JF - Mauerwerk N2 - The article presents the investigation of the seismic behaviour of a modern URM building located in the municipality of Finale Emilia in province of Modena, Northern Italy. The building is situated in the centre of the series of the 2012 Northern Italy earthquakes and has not suffered any damage during the earthquake series in 2012. The observed earthquake resistance of the building is compared with predicted resistances based on linear and nonlinear design approaches according to Eurocode. Furthermore, probabilistic analyses based on nonlinear calculation models taking into account scattering of the most relevant input parameters are carried out to identify their influence to the results and to derive fragility curves. Y1 - 2018 U6 - https://doi.org/10.1002/dama.201800013 SN - 1437-1022 VL - 22 IS - 4 SP - 238 EP - 250 PB - Ernst & Sohn CY - Berlin ER - TY - CHAP A1 - Butenweg, Christoph A1 - Marinkovic, Marko T1 - Damage reduction system for masonry infill walls under seismic loading T2 - ce/papers N2 - Reinforced concrete (RC) frames with masonry infills are frequently used in seismic regions all over the world. Generally masonry infills are considered as nonstructural elements and thus are typically neglected in the design process. However, the observations made after strong earthquakes have shown that masonry infills can modify the dynamic behavior of the structure significantly. The consequences were total collapses of buildings and loss of human lives. This paper presents the new system INODIS (Innovative Decoupled Infill System) developed within the European research project INSYSME (Innovative Systems for Earthquake Resistant Masonry Enclosures in RC Buildings). INODIS decouples the frame and the masonry infill by means of special U-shaped rubbers placed in between frame and infill. The effectiveness of the system was investigated by means of full scale tests on RC frames with masonry infills subjected to in-plane and out-of-plane loading. Furthermore small specimen tests were conducted to determine material characteristics of the components and the resistances of the connections. Finally, a micromodel was developed to simulate the in-plane behavior of RC frames infilled with AAC blocks with and without installation of the INODIS system. KW - earthquakes KW - in-plane and out-of-plane failure KW - INODIS KW - RC frames Y1 - 2018 U6 - https://doi.org/10.1002/cepa.863 N1 - Special Issue: ICAAC ‐ 6th International Conference on Autoclaved Aerated Concrete VL - 2 IS - 4 SP - 267 EP - 273 PB - Ernst & Sohn Verlag CY - Berlin ER - TY - JOUR A1 - Conzen, Catharina A1 - Albanna, Walid A1 - Weiss, Miriam A1 - Kürten, David A1 - Vilser, Walthard A1 - Kotliar, Konstantin A1 - Zäske, Charlotte A1 - Clusmann, Hans A1 - Schubert, Gerrit Alexander T1 - Vasoconstriction and Impairment of Neurovascular Coupling after Subarachnoid Hemorrhage: a Descriptive Analysis of Retinal Changes JF - Translational Stroke Research N2 - Impaired cerebral autoregulation and neurovascular coupling (NVC) contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). Retinal vessel analysis (RVA) allows non-invasive assessment of vessel dimension and NVC hereby demonstrating a predictive value in the context of various neurovascular diseases. Using RVA as a translational approach, we aimed to assess the retinal vessels in patients with SAH. RVA was performed prospectively in 24 patients with acute SAH (group A: day 5–14), in 11 patients 3 months after ictus (group B: day 90 ± 35), and in 35 age-matched healthy controls (group C). Data was acquired using a Retinal Vessel Analyzer (Imedos Systems UG, Jena) for examination of retinal vessel dimension and NVC using flicker-light excitation. Diameter of retinal vessels—central retinal arteriolar and venular equivalent—was significantly reduced in the acute phase (p < 0.001) with gradual improvement in group B (p < 0.05). Arterial NVC of group A was significantly impaired with diminished dilatation (p < 0.001) and reduced area under the curve (p < 0.01) when compared to group C. Group B showed persistent prolonged latency of arterial dilation (p < 0.05). Venous NVC was significantly delayed after SAH compared to group C (A p < 0.001; B p < 0.05). To our knowledge, this is the first clinical study to document retinal vasoconstriction and impairment of NVC in patients with SAH. Using non-invasive RVA as a translational approach, characteristic patterns of compromise were detected for the arterial and venous compartment of the neurovascular unit in a time-dependent fashion. Recruitment will continue to facilitate a correlation analysis with clinical course and outcome. Y1 - 2018 U6 - https://doi.org/10.1007/s12975-017-0585-8 SN - 1868-601X IS - 9 SP - 284 EP - 293 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Rieke, Christian A1 - Stollenwerk, Dominik A1 - Dahmen, Markus A1 - Pieper, Martin T1 - Modeling and optimization of a biogas plant for a demand-driven energy supply JF - Energy N2 - Due to the Renewable Energy Act, in Germany it is planned to increase the amount of renewable energy carriers up to 60%. One of the main problems is the fluctuating supply of wind and solar energy. Here biogas plants provide a solution, because a demand-driven supply is possible. Before running such a plant, it is necessary to simulate and optimize the process. This paper provides a new model of a biogas plant, which is as accurate as the standard ADM1 model. The advantage compared to ADM1 is that it is based on only four parameters compared to 28. Applying this model, an optimization was installed, which allows a demand-driven supply by biogas plants. Finally the results are confirmed by several experiments and measurements with a real test plant. Y1 - 2018 U6 - https://doi.org/10.1016/j.energy.2017.12.073 SN - 0360-5442 VL - 145 SP - 657 EP - 664 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Pielen, Michael A1 - Röth, Thilo A1 - Flatten, T. ED - Proff, H. T1 - Erfolgsfaktoren künftiger Geschäftsmodelle von urbanen, geteilten Mobilitätsdienstleistungen T2 - Mobilität und digitale Transformation. (9. Wissenschaftsforum Mobilität. Tagungsband) N2 - Digitalisierung bezeichnet die Nutzung großer Datenmengen, die zu einer umfassenden Vernetzung aller Bereiche der Wirtschaft und Gesellschaft führen wird (BMWi, 2015 und ähnlich Köhler/Wollschläger, 2014: 79). Sie umfasst die Erhebung von analogen Informationen („Big Data“ in einem engen Sinne; z.B. O´Leary, 2013), ihre Speicherung in einem digitaltechnischen System (lokale Speicherung oder „Cloud Computing“ durch die Weiterentwickelung des Internets; z.B. Hashem et al., 2015: 101), die Analyse und Interpretation sowie den Transfer in andere Systeme („Internet der Dinge“ bzw. „Internet of Things“; z.B. Ashton, 2009). Y1 - 2018 SN - 978-3-658-20779-3 U6 - https://doi.org/10.1007/978-3-658-20779-3_2 SP - 435 EP - 448 PB - Springer Gabler CY - Wiesbaden ER - TY - JOUR A1 - Bhattarai, Aroj A1 - Jabbari, Medisa A1 - Anding, Ralf A1 - Staat, Manfred T1 - Surgical treatment of vaginal vault prolapse using different prosthetic mesh implants: a finite element analysis JF - tm - Technisches Messen N2 - Particularly multiparous elderly women may suffer from vaginal vault prolapse after hysterectomy due to weak support from lax apical ligaments. A decreased amount of estrogen and progesterone in older age is assumed to remodel the collagen thereby reducing tissue stiffness. Sacrocolpopexy is either performed as open or laparoscopic surgery using prosthetic mesh implants to substitute lax ligaments. Y-shaped mesh models (DynaMesh, Gynemesh, and Ultrapro) are implanted in a 3D female pelvic floor finite element model in the extraperitoneal space from the vaginal cuff to the first sacral (S1) bone below promontory. Numerical simulations are conducted during Valsalva maneuver with weakened tissues modeled by reduced tissue stiffness. Tissues are modeled as incompressible, isotropic hyperelastic materials whereas the meshes are modeled either as orthotropic linear elastic or as isotropic hyperlastic materials. The positions of the vaginal cuff and the bladder base are calculated from the pubococcygeal line for female pelvic floor at rest, for prolapse and after repair using the three meshes. Due to mesh mechanics and mesh pore deformation along the loaded direction, the DynaMesh with regular rectangular mesh pores is found to provide better mechanical support to the organs than the Gynemesh and the Ultrapro with irregular hexagonal mesh pores. Insbesondere ältere, mehrgebährende Frauen leiden häufiger an einem Scheidenvorfall nach einer Hysterektomie aufgrund der schwachen Unterstützung durch laxe apikale Bänder. Es wird angenommen, dass eine verringerte Menge an Östrogen und Progesteron im höheren Alter das Kollagen umformt, wodurch die Gewebesteifigkeit reduziert wird. Die Sakrokolpopexie ist eine offene oder laparoskopische Operation, die mit prothetischen Netzimplantaten durchgeführt wird, um laxe Bänder zu ersetzen. Y-förmige Netzmodelle (DynaMesh, Gynemesh und Ultrapro) werden in einem 3D-Modell des weiblichen Beckenbodens im extraperitonealen Raum vom Vaginalstumpf bis zum Promontorium implantiert. Numerische Simulationen werden während des Valsalva-Manövers mit geschwächtem Gewebe durchgeführt, das durch eine reduzierte Gewebesteifigkeit modelliert wird. Die Gewebe werden als inkompressible, isotrop hyperelastische Materialien modelliert, während die Netze entweder als orthotrope linear elastische oder als isotrope hyperlastische Materialien modelliert werden. Die Positionen des Vaginalstumpfs, der Blase und der Harnröhrenachse werden anhand der Pubococcygeallinie aus der Ruhelage, für den Prolaps und nach der Reparatur unter Verwendung der drei Netze berechnet. Aufgrund der Netzmechanik und der Netzporenverformung bietet das DynaMesh mit regelmäßigen rechteckigen Netzporen eine bessere mechanische Unterstützung und eine Neupositionierung des Scheidengewölbes, der Blase und der Urethraachse als Gynemesh und Ultrapro mit unregelmäßigen hexagonalen Netzporen. Y1 - 2018 U6 - https://doi.org/10.1515/teme-2017-0115 SN - 2196-7113 VL - 85 IS - 5 SP - 331 EP - 342 PB - De Gruyter CY - Berlin ER -