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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.
Kinematics and kinetics of handcycling propulsion at increasing workloads in able-bodied subjects
(2018)
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.
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.
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.
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.
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.
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.
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.
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).
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.
Using the OpenSim software and verified anatomical data, a computer model for the calculation of biomechanical parameters is developed and used to determine the effect of a reattachment of the Supraspinatus muscle with a medial displacement of the muscle attachment point, which may be necessary for a rupture of the supraspinatus tendon. The results include the influence of the operation on basic biomechanical parameters such as the lever arm, as well as the calculated the muscle activations for the supraspinatus and deltoid. In addition, the influence on joint stability is examined by an analysis of the joint reaction force. The study provides a detailed description of the used model, as well as medical findings to a reattachment of the supraspinatus.
Mit der Software OpenSim und überprüften anatomischen Daten wird ein Computermodell zur Berechnung von biomechanischen Parametern entwickelt und genutzt, um den Effekt einer Refixierung des Supraspinatusmuskels mit einer medialen Verschiebung des Muskelansatzpunktes zu ermitteln, wie sie unter anderem nach einem Riss der Supraspinatussehne notwendig sein kann. Die Ergebnisse umfassen hierbei den Einfluss der Operation auf grundlegende biomechanische Parameter wie den Hebelarm sowie die berechneten Muskelaktivierungen für den Supraspinatus und Deltoideus. Zusätzlich wird der Einfluss auf die Gelenkstabilität betrachtet und durch eine Analyse der Gelenkreaktionskraft untersucht. Die Studie bietet eine detaillierte Beschreibung des genutzten Modells, sowie medizinische Erkenntnisse zu einer Refixierung des Supraspinatus.
An amperometric bi-enzyme biosensor based on substrate recycling principle for the amplification of the sensor signal has been developed for the detection of adrenaline in blood. Adrenaline can be used as biomarker verifying successful adrenal venous sampling procedure. The adrenaline biosensor has been realized via modification of a galvanic oxygen sensor with a bi-enzyme membrane combining a genetically modified laccase and a pyrroloquinoline quinone-dependent glucose dehydrogenase. The measurement conditions such as pH value and temperature were optimized to enhance the sensor performance. A high sensitivity and a low detection limit of about 0.5–1 nM adrenaline have been achieved in phosphate buffer at pH 7.4, relevant for measurements in blood samples. The sensitivity of the biosensor to other catecholamines such as noradrenaline, dopamine and dobutamine has been studied. Finally, the sensor has been successfully applied for the detection of adrenaline in human blood plasma.
In this work, a spore-based biosensor is evaluated to monitor the microbicidal efficacy of sterilization processes applying gaseous hydrogen peroxide (H2O2). The sensor is based on interdigitated electrode structures (IDEs) that have been fabricated by means of thin-film technologies. Impedimetric measurements are applied to study the effect of sterilization process on spores of Bacillus atrophaeus. This resilient microorganism is commonly used in industry to proof the sterilization efficiency. The sensor measurements are accompanied by conventional microbiological challenge tests, as well as morphological characterizations with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sensor measurements are correlated with the microbiological test routines. In both methods, namely the sensor-based and microbiological one, a tailing effect has been observed. The results are evaluated and discussed in a three-dimensional calibration plot demonstrating the sensor's suitability to enable a rapid process decision in terms of a successfully performed sterilization.
Pelvic floor dysfunction (PFD) is characterized by the failure of the levator ani (LA) muscle to maintain the pelvic hiatus, resulting in the descent of the pelvic organs below the pubococcygeal line. This chapter adopts the modified Humphrey material model to consider the effect of the muscle fiber on passive stretching of the LA muscle. The deformation of the LA muscle subjected to intra-abdominal pressure during Valsalva maneuver is compared with the magnetic resonance imaging (MRI) examination of a nulliparous female. Numerical result shows that the fiber-based Humphrey model simulates the muscle behavior better than isotropic constitutive models. Greater posterior movement of the LA muscle widens the levator hiatus due to lack of support from the anococcygeal ligament and the perineal structure as a consequence of birth-related injury and aging. Old and multiparous females with uncontrolled urogenital and rectal hiatus tend to develop PFDs such as prolapse and incontinence.
After menopause, decreased levels of estrogen and progesterone remodel the collagen of the soft tissues thereby reducing their stiffness. Stress urinary incontinence is associated with involuntary urine leakage due to pathological movement of the pelvic organs resulting from lax suspension system, fasciae, and ligaments. This study compares the changes in the orientation and position of the female pelvic organs due to weakened fasciae, ligaments, and their combined laxity. A mixture theory weighted by respective volume fraction of elastin-collagen fibre compound (5%), adipose tissue (85%), and smooth muscle (5%) is adopted to characterize the mechanical behaviour of the fascia. The load carrying response (other than the functional response to the pelvic organs) of each fascia component, pelvic organs, muscles, and ligaments are assumed to be isotropic, hyperelastic, and incompressible. Finite element simulations are conducted during Valsalva manoeuvre with weakened tissues modelled by reduced tissue stiffness. A significant dislocation of the urethrovesical junction is observed due to weakness of the fascia (13.89 mm) compared to the ligaments (5.47 mm). The dynamics of the pelvic floor observed in this study during Valsalva manoeuvre is associated with urethral-bladder hypermobility, greater levator plate angulation, and positive Q-tip test which are observed in incontinent females.
A new formulation for the prediction of free surface dynamics related to the turbulence occurring nearby is proposed. This formulation, altogether with a breakup criterion, can be used to compute the inception of self-aeration in high velocity flows like those occurring in hydraulic structures. Assuming a simple perturbation geometry, a kinematic and a non-linear momentum-based dynamic equation are formulated and forces acting on a control volume are approximated. Limiting steepness is proposed as an adequate breakup criterion. Role of the velocity fluctuations normal to the free surface is shown to be the main turbulence quantity related to self-aeration and the role of the scales contained in the turbulence spectrum are depicted. Surface tension force is integrated accounting for large displacements by using differential geometry for the curvature estimation. Gravity and pressure effects are also contemplated in the proposed formulation. The obtained equations can be numerically integrated for each wavelength, hence resulting in different growth rates and allowing computation of the free surface roughness wavelength distribution. Application to a prototype scale spillway (at the Aviemore dam) revealed that most unstable wavelength was close to the Taylor lengthscale. Amplitude distributions have been also obtained observing different scaling for perturbations stabilized by gravity or surface tension. The proposed theoretical framework represents a new conceptualization of self-aeration which explains the characteristic rough surface at the non-aerated region as well as other previous experimental observations which remained unresolved for several decades.
Der vorliegende Artikel fokussiert sich auf die weibliche Belastungsinkontinenz als Insuffizienz der Speicherfunktion der Blase, auch wenn im klinischen Alltag die Harninkontinenz der Frau häufig verschiedene Ursachen hat und insbesondere eine Belastungsinkontinenz im Alter und bei neurologischer Komorbidität nur selten isoliert vorkommt.
Das kleine Becken der Frau ist sowohl als Funktions- als auch als strukturelle Einheit zu betrachten. Dabei unterliegen bei der Frau Blase, Harnröhre, Gebärmutter und Enddarm sowie die muskulären und ligamentösen Strukturen des kleinen Beckens durch Fertilitätsphase, mögliche Schwangerschaften, Geburten und Menopausen-Phase, über das „normale Altern“ hinaus, gravierenden Veränderungen.
This article focuses on female stress incontinence in the form of pelvic floor dysfunction and urethral sphincter deficiency, although isolated stress incontinence accounts for less than half of all incontinence cases. Especially in women of old age and those with neurological comorbidities, the causes of incontinence are mostly multifactorial. Also it has to be considered that the female bladder, urethra, uterus and rectum as well as the muscular and ligamentous structures of the female pelvis minor are affected by phases of fertility, possible pregnancies, births and menopause in addition to the normal ageing process.
Die Fallstudie FAYMONVILLE beschäftigt sich damit, wie es dem Familienunternehmen Faymonville aus Ostbelgien gelungen ist, sich zu einem der führenden Hersteller in seiner Branche zu entwickeln. Die gezielte Identifizierung neuer Märkte, die Fokussierung auf die relevanten Kundenbedürfnisse und eine konsistente Produktpolitik mit einem abgestimmten Fertigungskonzept legen die Grundsteine für den Erfolg. Das vorliegende Fallbeispiel zeigt anschaulich, wie es gelingen kann, den prinzipiellen Widerspruch zwischen wirtschaftlicher und kundenindividueller Fertigung erfolgreich aufzulösen.
After a liver tumor intervention the medical doctor has to compare both pre and postoperative CT acquisitions to ensure that all carcinogenic cells are destroyed. A correct assessment of the intervention is of vital importance, since it will reduce the probability of tumor recurrence. Some methods have been proposed to support the medical doctors during the assessment process, however, all of them focus on secondary tumors. In this paper a tool is presented that enables the outcome validation for both primary and secondary tumors. Therefore, a multiphase registration (preoperative arterial and portal phases) followed by a registration between the pre and postoperative CT images is carried out. The first registration is in charge of the primary tumors that are only visible in the arterial phase. The secondary tumors will be incorporated in the second registration step. Finally, the part of the tumor that was not covered by the necrosis is quantified and visualized. The method has been tested in 9 patients, with an average registration error of 1.41 mm.