@article{AlbannaConzenWeissetal.2021, author = {Albanna, Walid and Conzen, Catharina and Weiss, Miriam and Seyfried, Katharina and Kotliar, Konstantin and Schmidt, Tobias Philip and Kuerten, David and Hescheler, J{\"u}rgen and Bruecken, Anne and Schmidt-Trucks{\"a}ss, Arno and Neumaier, Felix and Wiesmann, Martin and Clusmann, Hans and Schubert, Gerrit Alexander}, title = {Non-invasive assessment of neurovascular coupling after aneurysmal subarachnoid hemorrhage: a prospective observational trial using retinal vessel analysis}, series = {Frontiers in Neurology}, volume = {12}, journal = {Frontiers in Neurology}, number = {12}, issn = {1664-2295}, doi = {10.3389/fneur.2021.690183}, pages = {1 -- 15}, year = {2021}, abstract = {Delayed cerebral ischemia (DCI) is a common complication after aneurysmal subarachnoid hemorrhage (aSAH) and can lead to infarction and poor clinical outcome. The underlying mechanisms are still incompletely understood, but animal models indicate that vasoactive metabolites and inflammatory cytokines produced within the subarachnoid space may progressively impair and partially invert neurovascular coupling (NVC) in the brain. Because cerebral and retinal microvasculature are governed by comparable regulatory mechanisms and may be connected by perivascular pathways, retinal vascular changes are increasingly recognized as a potential surrogate for altered NVC in the brain. Here, we used non-invasive retinal vessel analysis (RVA) to assess microvascular function in aSAH patients at different times after the ictus.}, language = {en} } @incollection{Kotliar2021, author = {Kotliar, Konstantin}, title = {Ocular rigidity: clinical approach}, series = {Ocular Rigidity, Biomechanics and Hydrodynamics of the Eye}, booktitle = {Ocular Rigidity, Biomechanics and Hydrodynamics of the Eye}, editor = {Pallikaris, I. and Tsilimbaris, M. K. and Dastiridou, A. I.}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-64422-2}, doi = {10.1007/978-3-030-64422-2_2}, pages = {15 -- 43}, year = {2021}, abstract = {The term ocular rigidity is widely used in clinical ophthalmology. Generally it is assumed as a resistance of the whole eyeball to mechanical deformation and relates to biomechanical properties of the eye and its tissues. Basic principles and formulas for clinical tonometry, tonography and pulsatile ocular blood flow measurements are based on the concept of ocular rigidity. There is evidence for altered ocular rigidity in aging, in several eye diseases and after eye surgery. Unfortunately, there is no consensual view on ocular rigidity: it used to make a quite different sense for different people but still the same name. Foremost there is no clear consent between biomechanical engineers and ophthalmologists on the concept. Moreover ocular rigidity is occasionally characterized using various parameters with their different physical dimensions. In contrast to engineering approach, clinical approach to ocular rigidity claims to characterize the total mechanical response of the eyeball to its deformation without any detailed considerations on eye morphology or material properties of its tissues. Further to the previous chapter this section aims to describe clinical approach to ocular rigidity from the perspective of an engineer in an attempt to straighten out this concept, to show its advantages, disadvantages and various applications.}, language = {en} } @article{NeumaierKotliarHaerenetal.2021, author = {Neumaier, Felix and Kotliar, Konstantin and Haeren, Roel Hubert Louis and Temel, Yasin and L{\"u}ke, Jan Niklas and Seyam, Osama and Lindauer, Ute and Clusmann, Hans and Hescheler, J{\"u}rgen and Schubert, Gerrit Alexander and Schneider, Toni and Albanna, Walid}, title = {Retinal Vessel Responses to Flicker Stimulation Are Impaired in Ca v 2.3-Deficient Mice—An in- vivo Evaluation Using Retinal Vessel Analysis (RVA)}, series = {Frontiers in Neurology}, volume = {12}, journal = {Frontiers in Neurology}, publisher = {Frontiers}, doi = {10.3389/fneur.2021.659890}, pages = {1 -- 11}, year = {2021}, language = {en} } @article{TemizArtmannKurulgandemirciFıratetal.2021, author = {Temiz Artmann, Ayseg{\"u}l and Kurulgan demirci, Eylem and F{\i}rat, Ipek Seda and Oflaz, Hakan and Artmann, Gerhard}, title = {Recombinant activated protein C (rhAPC) affects lipopolysaccharide-induced mechanical compliance changes and beat frequency of mESC-derived cardiomyocyte monolayers}, series = {SHOCK}, journal = {SHOCK}, publisher = {Wolters Kluwer}, address = {K{\"o}ln}, issn = {1540-0514}, doi = {10.1097/SHK.0000000000001845}, year = {2021}, language = {en} } @article{SeefeldtDachwald2021, author = {Seefeldt, Patric and Dachwald, Bernd}, title = {Temperature increase on folded solar sail membranes}, series = {Advances in Space Research}, volume = {67}, journal = {Advances in Space Research}, number = {9}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0273-1177}, doi = {10.1016/j.asr.2020.09.026}, pages = {2688 -- 2695}, year = {2021}, language = {en} } @article{GermanMikuckiWelchetal.2021, author = {German, Laura and Mikucki, Jill A. and Welch, Susan A. and Welch, Kathleen A. and Lutton, Anthony and Dachwald, Bernd and Kowalski, Julia and Heinen, Dirk and Feldmann, Marco and Francke, Gero and Espe, Clemens and Lyons, W. Berry}, title = {Validation of sampling antarctic subglacial hypersaline waters with an electrothermal ice melting probe (IceMole) for environmental analytical geochemistry}, series = {International Journal of Environmental Analytical Chemistry}, volume = {101}, journal = {International Journal of Environmental Analytical Chemistry}, number = {15}, publisher = {Taylor \& Francis}, address = {London}, issn = {0306-7319}, doi = {10.1080/03067319.2019.1704750}, pages = {2654 -- 2667}, year = {2021}, abstract = {Geochemical characterisation of hypersaline waters is difficult as high concentrations of salts hinder the analysis of constituents at low concentrations, such as trace metals, and the collection of samples for trace metal analysis in natural waters can be easily contaminated. This is particularly the case if samples are collected by non-conventional techniques such as those required for aquatic subglacial environments. In this paper we present the first analysis of a subglacial brine from Taylor Valley, (~ 78°S), Antarctica for the trace metals: Ba, Co, Mo, Rb, Sr, V, and U. Samples were collected englacially using an electrothermal melting probe called the IceMole. This probe uses differential heating of a copper head as well as the probe's sidewalls and an ice screw at the melting head to move through glacier ice. Detailed blanks, meltwater, and subglacial brine samples were collected to evaluate the impact of the IceMole and the borehole pump, the melting and collection process, filtration, and storage on the geochemistry of the samples collected by this device. Comparisons between melt water profiles through the glacier ice and blank analysis, with published studies on ice geochemistry, suggest the potential for minor contributions of some species Rb, As, Co, Mn, Ni, NH4+, and NO2-+NO3- from the IceMole. The ability to conduct detailed chemical analyses of subglacial fluids collected with melting probes is critical for the future exploration of the hundreds of deep subglacial lakes in Antarctica.}, language = {en} } @misc{JungMuellerStaat2021, author = {Jung, Alexander and M{\"u}ller, Wolfram and Staat, Manfred}, title = {Corrigendum to "Wind and fairness in ski jumping: A computer modelling analysis" [J. Biomech. 75 (2018) 147-153]}, series = {Journal of Biomechanics}, volume = {128}, journal = {Journal of Biomechanics}, number = {Article number: 110690}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0021-9290}, doi = {10.1016/j.jbiomech.2021.110690}, pages = {1 Seite}, year = {2021}, language = {en} } @article{HacklBuessKammerlohretal.2021, author = {Hackl, Michael and Buess, Eduard and Kammerlohr, Sandra and Nacov, Julia and Staat, Manfred and Leschinger, Tim and M{\"u}ller, Lars P. and Wegmann, Kilian}, title = {A "comma sign"-directed subscapularis repair in anterosuperior rotator cuff tears yields biomechanical advantages in a cadaveric model}, series = {The american journal of sports medicine}, volume = {49}, journal = {The american journal of sports medicine}, number = {12}, publisher = {Sage}, address = {London}, issn = {1552-3365}, doi = {10.1177/03635465211031506}, pages = {3212 -- 3217}, year = {2021}, abstract = {Background: Additional stabilization of the "comma sign" in anterosuperior rotator cuff repair has been proposed to provide biomechanical benefits regarding stability of the repair. Purpose: This in vitro investigation aimed to investigate the influence of a comma sign-directed reconstruction technique for anterosuperior rotator cuff tears on the primary stability of the subscapularis tendon repair. Study Design: Controlled laboratory study. Methods: A total of 18 fresh-frozen cadaveric shoulders were used in this study. Anterosuperior rotator cuff tears (complete full-thickness tear of the supraspinatus and subscapularis tendons) were created, and supraspinatus repair was performed with a standard suture bridge technique. The subscapularis was repaired with either a (1) single-row or (2) comma sign technique. A high-resolution 3D camera system was used to analyze 3-mm and 5-mm gap formation at the subscapularis tendon-bone interface upon incremental cyclic loading. Moreover, the ultimate failure load of the repair was recorded. A Mann-Whitney test was used to assess significant differences between the 2 groups. Results: The comma sign repair withstood significantly more loading cycles than the single-row repair until 3-mm and 5-mm gap formation occurred (P≤ .047). The ultimate failure load did not reveal any significant differences when the 2 techniques were compared (P = .596). Conclusion: The results of this study show that additional stabilization of the comma sign enhanced the primary stability of subscapularis tendon repair in anterosuperior rotator cuff tears. Although this stabilization did not seem to influence the ultimate failure load, it effectively decreased the micromotion at the tendon-bone interface during cyclic loading. Clinical Relevance: The proposed technique for stabilization of the comma sign has shown superior biomechanical properties in comparison with a single-row repair and might thus improve tendon healing. Further clinical research will be necessary to determine its influence on the functional outcome.}, language = {en} } @article{RichterBraunsteinStaeudleetal.2021, author = {Richter, Charlotte and Braunstein, Bjoern and St{\"a}udle, Benjamin and Attias, Julia and Suess, Alexander and Weber, Tobias and Mileva, Katja N. and Rittweger, Joern and Green, David A. and Albracht, Kirsten}, title = {Gastrocnemius medialis contractile behavior is preserved during 30\% body weight supported gait training}, series = {Frontiers in Sports and Active Living}, volume = {2021}, journal = {Frontiers in Sports and Active Living}, number = {2}, publisher = {Frontiers}, address = {Lausanne}, issn = {2624-9367}, doi = {10.3389/fspor.2020.614559}, pages = {Artikel 614559}, year = {2021}, abstract = {Rehabilitative body weight supported gait training aims at restoring walking function as a key element in activities of daily living. Studies demonstrated reductions in muscle and joint forces, while kinematic gait patterns appear to be preserved with up to 30\% weight support. However, the influence of body weight support on muscle architecture, with respect to fascicle and series elastic element behavior is unknown, despite this having potential clinical implications for gait retraining. Eight males (31.9 ± 4.7 years) walked at 75\% of the speed at which they typically transition to running, with 0\% and 30\% body weight support on a lower-body positive pressure treadmill. Gastrocnemius medialis fascicle lengths and pennation angles were measured via ultrasonography. Additionally, joint kinematics were analyzed to determine gastrocnemius medialis muscle-tendon unit lengths, consisting of the muscle's contractile and series elastic elements. Series elastic element length was assessed using a muscle-tendon unit model. Depending on whether data were normally distributed, a paired t-test or Wilcoxon signed rank test was performed to determine if body weight supported walking had any effects on joint kinematics and fascicle-series elastic element behavior. Walking with 30\% body weight support had no statistically significant effect on joint kinematics and peak series elastic element length. Furthermore, at the time when peak series elastic element length was achieved, and on average across the entire stance phase, muscle-tendon unit length, fascicle length, pennation angle, and fascicle velocity were unchanged with respect to body weight support. In accordance with unchanged gait kinematics, preservation of fascicle-series elastic element behavior was observed during walking with 30\% body weight support, which suggests transferability of gait patterns to subsequent unsupported walking.}, language = {en} } @article{AkimbekovDigelTastambeketal.2021, author = {Akimbekov, Nuraly S. and Digel, Ilya and Tastambek, Kuanysh T. and Sherelkhan, Dinara K. and Jussupova, Dariya B. and Altynbay, Nazym P.}, title = {Low-rank coal as a source of humic substances for soil amendment and fertility management}, series = {Agriculture}, volume = {11}, journal = {Agriculture}, number = {12}, publisher = {MDPI}, address = {Basel}, issn = {2077-0472}, doi = {10.3390/agriculture11121261}, pages = {25 Seiten}, year = {2021}, abstract = {Humic substances (HS), as important environmental components, are essential to soil health and agricultural sustainability. The usage of low-rank coal (LRC) for energy generation has declined considerably due to the growing popularity of renewable energy sources and gas. However, their potential as soil amendment aimed to maintain soil quality and productivity deserves more recognition. LRC, a highly heterogeneous material in nature, contains large quantities of HS and may effectively help to restore the physicochemical, biological, and ecological functionality of soil. Multiple emerging studies support the view that LRC and its derivatives can positively impact the soil microclimate, nutrient status, and organic matter turnover. Moreover, the phytotoxic effects of some pollutants can be reduced by subsequent LRC application. Broad geographical availability, relatively low cost, and good technical applicability of LRC offer the advantage of easy fulfilling soil amendment and conditioner requirements worldwide. This review analyzes and emphasizes the potential of LRC and its numerous forms/combinations for soil amelioration and crop production. A great benefit would be a systematic investment strategy implicating safe utilization and long-term application of LRC for sustainable agricultural production.}, language = {en} } @article{HeinEubanksHibberdetal.2020, author = {Hein, Andreas M. and Eubanks, T. Marshall and Hibberd, Adam and Fries, Dan and Schneider, Jean and Lingam, Manasvi and Kennedy, Robert and Perakis, Nikolaos and Dachwald, Bernd and Kervella, Pierre}, title = {Interstellar Now! Missions to and sample returns from nearby interstellar objects}, publisher = {Elsevier}, address = {Amsterdam}, pages = {1 -- 8}, year = {2020}, abstract = {The recently discovered first high velocity hyperbolic objects passing through the Solar System, 1I/'Oumuamua and 2I/Borisov, have raised the question about near term missions to Interstellar Objects. In situ spacecraft exploration of these objects will allow the direct determination of both their structure and their chemical and isotopic composition, enabling an entirely new way of studying small bodies from outside our solar system. In this paper, we map various Interstellar Object classes to mission types, demonstrating that missions to a range of Interstellar Object classes are feasible, using existing or near-term technology. We describe flyby, rendezvous and sample return missions to interstellar objects, showing various ways to explore these bodies characterizing their surface, dynamics, structure and composition. Interstellar objects likely formed very far from the solar system in both time and space; their direct exploration will constrain their formation and history, situating them within the dynamical and chemical evolution of the Galaxy. These mission types also provide the opportunity to explore solar system bodies and perform measurements in the far outer solar system.}, language = {en} } @article{RauschHarbrechtKahmannetal.2020, author = {Rausch, Valentin and Harbrecht, Andreas and Kahmann, Stephanie Lucina and Fenten, Thomas and Jovanovic, Nebojsa and Hackl, Michael and M{\"u}ller, Lars P. and Staat, Manfred and Wegmann, Kilian}, title = {Osteosynthesis of Phalangeal Fractures: Biomechanical Comparison of Kirschner Wires, Plates, and Compression Screws}, series = {The Journal of Hand Surgery}, volume = {45}, journal = {The Journal of Hand Surgery}, number = {10}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0363-5023}, doi = {10.1016/j.jhsa.2020.04.010}, pages = {987.e1 -- 987.e8}, year = {2020}, abstract = {Purpose The aim of this study was to compare several osteosynthesis techniques (intramedullary headless compression screws, T-plates, and Kirschner wires) for distal epiphyseal fractures of proximal phalanges in a human cadaveric model. Methods A total of 90 proximal phalanges from 30 specimens (index, ring, and middle fingers) were used for this study. After stripping off all soft tissue, a transverse distal epiphyseal fracture was simulated at the proximal phalanx. The 30 specimens were randomly assigned to 1 fixation technique (30 per technique), either a 3.0-mm intramedullary headless compression screw, locking plate fixation with a 2.0-mm T-plate, or 2 oblique 1.0-mm Kirschner wires. Displacement analysis (bending, distraction, and torsion) was performed using optical tracking of an applied random speckle pattern after osteosynthesis. Biomechanical testing was performed with increasing cyclic loading and with cyclic load to failure using a biaxial torsion-tension testing machine. Results Cannulated intramedullary compression screws showed significantly less displacement at the fracture site in torsional testing. Furthermore, screws were significantly more stable in bending testing. Kirschner wires were significantly less stable than plating or screw fixation in any cyclic load to failure test setup. Conclusions Intramedullary compression screws are a highly stable alternative in the treatment of transverse distal epiphyseal phalangeal fractures. Kirschner wires seem to be inferior regarding displacement properties and primary stability. Clinical relevance Fracture fixation of phalangeal fractures using plate osteosynthesis may have the advantage of a very rigid reduction, but disadvantages such as stiffness owing to the more invasive surgical approach and soft tissue irritation should be taken into account. Headless compression screws represent a minimally invasive choice for fixation with good biomechanical properties.}, language = {en} } @article{JungStaat2020, author = {Jung, Alexander and Staat, Manfred}, title = {Erratum to "Modeling and simulation of human induced pluripotent stem cell-derived cardiac tissue" [GAMM-Mitteilungen, (2019), 42, 4, 10.1002/gamm.201900002]}, series = {GAMM-Mitteilungen}, volume = {43}, journal = {GAMM-Mitteilungen}, number = {4}, publisher = {Wiley-VCH GmbH}, address = {Weinheim}, issn = {1522-2608}, doi = {10.1002/gamm.202000011}, year = {2020}, language = {en} } @article{RauschKahmannBaltschunetal.2020, author = {Rausch, Valentin and Kahmann, Stephanie Lucina and Baltschun, Christoph and Staat, Manfred and M{\"u}ller, Lars P. and Wegmann, Kilian}, title = {Pressure distribution to the distal biceps tendon at the radial tuberosity: a biomechanical study}, series = {The Journal of Hand Surgery}, volume = {45}, journal = {The Journal of Hand Surgery}, number = {8}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0363-5023}, doi = {10.1016/j.jhsa.2020.01.006}, pages = {776.e1 -- 776.e9}, year = {2020}, abstract = {Purpose Mechanical impingement at the narrow radioulnar space of the tuberosity is believed to be an etiological factor in the injury of the distal biceps tendon. The aim of the study was to compare the pressure distribution at the proximal radioulnar space between 2 fixation techniques and the intact state. Methods Six right arms and 6 left arms from 5 female and 6 male frozen specimens were used for this study. A pressure transducer was introduced at the height of the radial tuberosity with the intact distal biceps tendon and after 2 fixation methods: the suture-anchor and the cortical button technique. The force (N), maximum pressure (kPa) applied to the radial tuberosity, and the contact area (mm²) of the radial tuberosity with the ulna were measured and differences from the intact tendon were detected from 60° supination to 60° pronation in 15° increments with the elbow in full extension and in 45° and 90° flexion of the elbow. Results With the distal biceps tendon intact, the pressures during pronation were similar regardless of extension and flexion and were the highest at 60° pronation with 90° elbow flexion (23.3 ± 53.5 kPa). After repair of the tendon, the mean peak pressure, contact area, and total force showed an increase regardless of the fixation technique. Highest peak pressures were found using the cortical button technique at 45° flexion of the elbow and 60° pronation. These differences were significantly different from the intact tendon. The contact area was significantly larger in full extension and 15°, 30°, and 60° pronation using the cortical button technique. Conclusions Pressures on the distal biceps tendon at the radial tuberosity increase during pronation, especially after repair of the tendon. Clinical relevance Mechanical impingement could play a role in both the etiology of primary distal biceps tendon ruptures and the complications occurring after fixation of the tendon using certain techniques.}, language = {en} } @article{HorbachStaatPerezVianaetal.2020, author = {Horbach, Andreas and Staat, Manfred and Perez-Viana, Daniel and Simmen, Hans-Peter and Neuhaus, Valentin and Pape, Hans-Christoph and Prescher, Andreas and Ciritsis, Bernhard}, title = {Biomechanical in vitro examination of a standardized low-volume tubular femoroplasty}, series = {Clinical Biomechanics}, volume = {80}, journal = {Clinical Biomechanics}, number = {Art. 105104}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.clinbiomech.2020.105104}, year = {2020}, abstract = {Background Osteoporosis is associated with the risk of fractures near the hip. Age and comorbidities increase the perioperative risk. Due to the ageing population, fracture of the proximal femur also proves to be a socio-economic problem. Preventive surgical measures have hardly been used so far. Methods 10 pairs of human femora from fresh cadavers were divided into control and low-volume femoroplasty groups and subjected to a Hayes fall-loading fracture test. The results of the respective localization and classification of the fracture site, the Singh index determined by computed tomography (CT) examination and the parameters in terms of fracture force, work to fracture and stiffness were evaluated statistically and with the finite element method. In addition, a finite element parametric study with different position angles and variants of the tubular geometry of the femoroplasty was performed. Findings Compared to the control group, the work to fracture could be increased by 33.2\%. The fracture force increased by 19.9\%. The used technique and instrumentation proved to be standardized and reproducible with an average poly(methyl methacrylate) volume of 10.5 ml. The parametric study showed the best results for the selected angle and geometry. Interpretation The cadaver studies demonstrated the biomechanical efficacy of the low-volume tubular femoroplasty. The numerical calculations confirmed the optimal choice of positioning as well as the inner and outer diameter of the tube in this setting. The standardized minimally invasive technique with the instruments developed for it could be used in further comparative studies to confirm the measured biomechanical results.}, language = {en} } @article{KnoxBruggemannGossmannetal.2020, author = {Knox, Ronald and Bruggemann, Andrea and Gossmann, Matthias and Thomas, Ulrich and Horv{\´a}th, Andr{\´a}s and Dragicevic, Elena and Stoelzle-Feix, Sonja and Fertig, Niels and Jung, Alexander and Raman, Aravind Hariharan and Staat, Manfred and Linder, Peter}, title = {Combining physiological relevance and throughput for in vitro cardiac contractility measurement}, series = {Biophysical Journal}, volume = {118}, journal = {Biophysical Journal}, number = {Issue 3, Supplement 1}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0006-3495}, doi = {10.1016/j.bpj.2019.11.3104}, pages = {570a}, year = {2020}, abstract = {Despite increasing acceptance of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in safety pharmacology, controversy remains about the physiological relevance of existing in vitro models for their mechanical testing. We hypothesize that existing signs of immaturity of the cell models result from an improper mechanical environment. We cultured hiPSC-CMs in a 96-well format on hyperelastic silicone membranes imitating their native mechanical environment, resulting in physiological responses to compound stimuli.We validated cell responses on the FLEXcyte 96, with a set of reference compounds covering a broad range of cellular targets, including ion channel modulators, adrenergic receptor modulators and kinase inhibitors. Acute (10 - 30 min) and chronic (up to 7 days) effects were investigated. Furthermore, the measurements were complemented with electromechanical models based on electrophysiological recordings of the used cell types.hiPSC-CMs were cultured on freely-swinging, ultra-thin and hyperelastic silicone membranes. The weight of the cell culture medium deflects the membranes downwards. Rhythmic contraction of the hiPSC-CMs resulted in dynamic deflection changes which were quantified by capacitive distance sensing. The cells were cultured for 7 days prior to compound addition. Acute measurements were conducted 10-30 minutes after compound addition in standard culture medium. For chronic treatment, compound-containing medium was replaced daily for up to 7 days. Electrophysiological properties of the employed cell types were recorded by automated patch-clamp (Patchliner) and the results were integrated into the electromechanical model of the system.Calcium channel agonist S Bay K8644 and beta-adrenergic stimulator isoproterenol induced significant positive inotropic responses without additional external stimulation. Kinase inhibitors displayed cardiotoxic effects on a functional level at low concentrations. The system-integrated analysis detected alterations in beating shape as well as frequency and arrhythmic events and we provide a quantitative measure of these.}, language = {en} } @article{QuittmannMeskemperAlbrachtetal.2020, author = {Quittmann, Oliver J. and Meskemper, Joshua and Albracht, Kirsten and Abel, Thomas and Foitschik, Tina and Str{\"u}der, Heiko K.}, title = {Normalising surface EMG of ten upper-extremity muscles in handcycling: Manual resistance vs. sport-specific MVICs}, series = {Journal of Electromyography and Kinesiology}, volume = {51}, journal = {Journal of Electromyography and Kinesiology}, number = {Article 102402}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1050-6411}, doi = {10.1016/j.jelekin.2020.102402}, year = {2020}, abstract = {Muscular activity in terms of surface electromyography (sEMG) is usually normalised to maximal voluntary isometric contractions (MVICs). This study aims to compare two different MVIC-modes in handcycling and examine the effect of moving average window-size. Twelve able-bodied male competitive triathletes performed ten MVICs against manual resistance and four sport-specific trials against fixed cranks. sEMG of ten muscles [M. trapezius (TD); M. pectoralis major (PM); M. deltoideus, Pars clavicularis (DA); M. deltoideus, Pars spinalis (DP); M. biceps brachii (BB); M. triceps brachii (TB); forearm flexors (FC); forearm extensors (EC); M. latissimus dorsi (LD) and M. rectus abdominis (RA)] was recorded and filtered using moving average window-sizes of 150, 200, 250 and 300 ms. Sport-specific MVICs were higher compared to manual resistance for TB, DA, DP and LD, whereas FC, TD, BB and RA demonstrated lower values. PM and EC demonstrated no significant difference between MVIC-modes. Moving average window-size had no effect on MVIC outcomes. MVIC-mode should be taken into account when normalised sEMG data are illustrated in handcycling. Sport-specific MVICs seem to be suitable for some muscles (TB, DA, DP and LD), but should be augmented by MVICs against manual/mechanical resistance for FC, TD, BB and RA.}, language = {en} } @article{KoppSchunckGosauetal.2020, author = {Kopp, Alexander and Schunck, Laura and Gosau, Martin and Smeets, Ralf and Burg, Simon and Fuest, Sandra and Kr{\"o}ger, Nadja and Zinser, Max and Krohn, Sebastian and Behbahani, Mehdi and K{\"o}pf, Marius and Lauts, Lisa and Rutkowski, Rico}, title = {Influence of the casting concentration on the mechanical and optical properties of Fa/CaCl2-derived silk fibroin membranes}, series = {International Journal of Molecular Sciences}, volume = {21}, journal = {International Journal of Molecular Sciences}, number = {18 art. no. 6704}, publisher = {MDPI}, address = {Basel}, issn = {1422-0067}, doi = {10.3390/ijms21186704}, year = {2020}, abstract = {In this study, we describe the manufacturing and characterization of silk fibroin membranes derived from the silkworm Bombyx mori. To date, the dissolution process used in this study has only been researched to a limited extent, although it entails various potential advantages, such as reduced expenses and the absence of toxic chemicals in comparison to other conventional techniques. Therefore, the aim of this study was to determine the influence of different fibroin concentrations on the process output and resulting membrane properties. Casted membranes were thus characterized with regard to their mechanical, structural and optical assets via tensile testing, SEM, light microscopy and spectrophotometry. Cytotoxicity was evaluated using BrdU, XTT, and LDH assays, followed by live-dead staining. The formic acid (FA) dissolution method was proven to be suitable for the manufacturing of transparent and mechanically stable membranes. The fibroin concentration affects both thickness and transparency of the membranes. The membranes did not exhibit any signs of cytotoxicity. When compared to other current scientific and technical benchmarks, the manufactured membranes displayed promising potential for various biomedical applications. Further research is nevertheless necessary to improve reproducible manufacturing, including a more uniform thickness, less impurity and physiological pH within the membranes.}, language = {en} } @article{QuittmannAbelAlbrachtetal.2020, author = {Quittmann, Oliver J. and Abel, Thomas and Albracht, Kirsten and Meskemper, Joshua and Foitschik, Tina and Str{\"u}der, Heiko K.}, title = {Biomechanics of handcycling propulsion in a 30-min continuous load test at lactate threshold: Kinetics, kinematics, and muscular activity in able-bodied participants}, series = {European Journal of Applied Physiology}, journal = {European Journal of Applied Physiology}, number = {120}, publisher = {Springer}, address = {Heidelberg}, issn = {1439-6327}, doi = {10.1007/s00421-020-04373-x}, pages = {1403 -- 1415}, year = {2020}, abstract = {Purpose This study aims to investigate the biomechanics of handcycling during a continuous load trial (CLT) to assess the mechanisms underlying fatigue in upper body exercise. Methods Twelve able-bodied triathletes performed a 30-min CLT at a power output corresponding to lactate threshold in a racing recumbent handcycle mounted on a stationary ergometer. During the CLT, ratings of perceived exertion (RPE), tangential crank kinetics, 3D joint kinematics, and muscular activity of ten muscles of the upper extremity and trunk were examined using motion capturing and surface electromyography. Results During the CLT, spontaneously chosen cadence and RPE increased, whereas crank torque decreased. Rotational work was higher during the pull phase. Peripheral RPE was higher compared to central RPE. Joint range of motion decreased for elbow-flexion and radial-duction. Integrated EMG (iEMG) increased in the forearm flexors, forearm extensors, and M. deltoideus (Pars spinalis). An earlier onset of activation was found for M. deltoideus (Pars clavicularis), M. pectoralis major, M. rectus abdominis, M. biceps brachii, and the forearm flexors. Conclusion Fatigue-related alterations seem to apply analogously in handcycling and cycling. The most distal muscles are responsible for force transmission on the cranks and might thus suffer most from neuromuscular fatigue. The findings indicate that peripheral fatigue (at similar lactate values) is higher in handcycling compared to leg cycling, at least for inexperienced participants. An increase in cadence might delay peripheral fatigue by a reduced vascular occlusion. We assume that the gap between peripheral and central fatigue can be reduced by sport-specific endurance training.}, language = {en} } @inproceedings{PohleFroehlichDalitzRichteretal.2020, author = {Pohle-Fr{\"o}hlich, Regina and Dalitz, Christoph and Richter, Charlotte and Hahnen, Tobias and St{\"a}udle, Benjamin and Albracht, Kirsten}, title = {Estimation of muscle fascicle orientation in ultrasonic images}, series = {Proceedings of the 15th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications - Volume 5}, booktitle = {Proceedings of the 15th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications - Volume 5}, publisher = {SciTePress}, address = {Set{\´u}bal, Portugal}, isbn = {978-989-758-402-2}, doi = {10.5220/0008933900790086}, pages = {79 -- 86}, year = {2020}, abstract = {We compare four different algorithms for automatically estimating the muscle fascicle angle from ultrasonic images: the vesselness filter, the Radon transform, the projection profile method and the gray level cooccurence matrix (GLCM). The algorithm results are compared to ground truth data generated by three different experts on 425 image frames from two videos recorded during different types of motion. The best agreement with the ground truth data was achieved by a combination of pre-processing with a vesselness filter and measuring the angle with the projection profile method. The robustness of the estimation is increased by applying the algorithms to subregions with high gradients and performing a LOESS fit through these estimates.}, language = {en} }