TY  - JOUR
A1  - Stäudle, Benjamin
A1  - Seynnes, Olivier
A1  - Laps, Guido
A1  - Göll, Fabian
A1  - Brüggemann, Gert-Peter
A1  - Albracht, Kirsten
T1  - Recovery from achilles tendon repair: a combination of Postsurgery Outcomes and Insufficient remodeling of muscle and tendon
JF  - Medicine & Science in Sports & Exercise
N2  - Achilles tendon rupture (ATR) patients have persistent functional deficits in the triceps surae muscle–tendon unit (MTU). The complex remodeling of the MTU accompanying these deficits remains poorly understood. The purpose of the present study was to associate in vivo and in silico data to investigate the relations between changes inMTU properties and strength deficits inATR patients. Methods: Elevenmale subjects who had undergone surgical repair of complete unilateral ATR were examined 4.6 ± 2.0 (mean ± SD) yr after rupture. Gastrocnemius medialis (GM) tendon stiffness, morphology, and muscle architecture were determined using ultrasonography. The force–length relation of the plantar flexor muscles was assessed at five ankle joint angles. In addition, simulations (OpenSim) of the GM MTU force–length properties were performed with various iterations of MTU properties found between the unaffected and the affected side. Results: The affected side of the patients displayed a longer, larger, and stiffer GM tendon (13% ± 10%, 105% ± 28%, and 54% ± 24%, respectively) compared with the unaffected side. The GM muscle fascicles of the affected side were shorter (32% ± 12%) and with greater pennation angles (31% ± 26%). A mean deficit in plantarflexion moment of 31% ± 10% was measured. Simulations indicate that pairing an intact muscle with a longer tendon shifts the optimal angular range of peak force outside physiological angular ranges, whereas the shorter muscle fascicles and tendon stiffening seen in the affected side decrease this shift, albeit incompletely. Conclusions: These results suggest that the substantial changes in MTU properties found in ATR patients may partly result from compensatory remodeling, although this process appears insufficient to fully restore muscle function.
KW  - Tendon Rupture
KW  - Stiffness
KW  - Simulation
KW  - Muscle Force
KW  - Muscle Fascicle
Y1  - 2021
U6  - http://dx.doi.org/10.1249/MSS.0000000000002592
SN  - 1530-0315
VL  - 53
IS  - 7
SP  - 1356
EP  - 1366
PB  - American College of Sports Medicine
CY  - Philadelphia, Pa.
ER  - 
TY  - JOUR
A1  - Monti, Elena
A1  - Waldvogel, Janice
A1  - Ritzmann, Ramona
A1  - Freyler, Kathrin
A1  - Albracht, Kirsten
A1  - Helm, Michael
A1  - De Cesare, Niccolò
A1  - Pavan, Piero
A1  - Reggiani, Carlo
A1  - Gollhofer, Albert
A1  - Narici, Marco Vincenzo
T1  - Muscle in variable gravity: “I do not know where I am, but I know what to do”
JF  - Frontiers in Physiology
N2  - Performing tasks, such as running and jumping, requires activation of the agonist and antagonist muscles before (motor unit pre-activation) and during movement performance (Santello and Mcdonagh, 1998). A well-timed and regulated muscle activation elicits a stretch-shortening cycle (SSC) response, naturally occurring in bouncing movements (Ishikawa and Komi, 2004; Taube et al., 2012). By definition, the SSC describes the stretching of a pre-activated muscle-tendon complex immediately followed by a muscle shortening in the concentric push-off phase (Komi, 1984).
Given the importance of SSC actions for human movement, it is not surprising that many studies investigated the biomechanics of this phenomenon; in particular, drop jumps (DJs) represent a good paradigm to study muscle fascicle and tendon behavior in ballistic movements involving the SSC.
Within a DJ, three main phases [pre-activation, braking, and push-off (PO; Komi, 2000)] have been recognized and extensively studied in common and challenging conditions, such as changes in load, falling height, or simulated hypo-gravity (Avela et al., 1994; Arampatzis et al., 2001; Fukashiro et al., 2005; Ishikawa et al., 2005; Sousa et al., 2007; Ritzmann et al., 2016; Helm et al., 2020).
These studies show that the timing and amount of triceps-surae muscle-tendon unit pre-activation in DJs are differentially regulated based on the load applied to the muscle, being optimal in normal “Earth” gravity conditions (Avela et al., 1994), but decreased in simulated hypo-gravity, hyper-gravity (Avela et al., 1994; Ritzmann et al., 2016), or unknown conditions (i.e., unknown falling heights; Helm et al., 2020). Some authors indicated that, when falling from heights different from the optimal one [defined as the drop height giving a maximum DJ performance indicated as peak ground reaction force (GRF) or jump high], electromyographic (EMG) activity of the plantar flexors increases from lower than optimal to higher than optimal heights (Ishikawa and Komi, 2004; Sousa et al., 2007).
These findings highlight the ability of the central nervous system to regulate the timing and amount of pre-activation according to different jumping conditions, thus regulating muscle fascicle length, tendon and joint stiffness as well as position, in order to safely land on the ground and quickly re-bounce.
Similarly, to pre-activation, also in the braking phase, the plantar flexors are differentially regulated. In optimal height (i.e., load) jumping conditions, gastrocnemius medialis (GM) fascicles shorten at early ground contact (possibly due to the intervention of the stretch reflex; Gollhofer et al., 1992) and behave quasi-isometrically in the late braking phase, enabling tendon elongation, and storage of elastic energy (Gollhofer et al., 1992; Fukashiro et al., 2005; Sousa et al., 2007). When increasing the falling height (augmenting the impact GRF), the quasi-isometric behavior of fascicles disappears, and fast fascicle lengthening occurs (Ishikawa et al., 2005; Sousa et al., 2007).
In the third and last PO phase, fascicles shorten and the tendon releases the elastic energy previously stored. Bobbert et al. (1987) reported no influence of jumping height on the work done and on the net vertical impulse assessed during PO; this observation suggests that, despite an optimal DJ performance might be achieved only in specific conditions (falling heights, loads), the central nervous system seems to be able to regulate muscle behavior in order to effectively perform the required task also in challenging situations.
Although the regulation of triceps-surae muscle-tendon unit in DJs has been extensively investigated, very few studies focused on sarcomeres behavior during the performance of this SSC movement (Kurokawa et al., 2003; Fukashiro et al., 2005, 2006). Sarcomeres represent muscle contractile units and are known to express different amounts of force depending on their length (Gordon et al., 1966; Walker and Schrodt, 1974); thus, understanding the time course of their responses during DJs is fundamental to gain further insights into muscle force-generating capacity. In vivo measurement of sarcomere length in humans has been so far been performed only in static positions and under highly controlled experimental conditions (Llewellyn et al., 2008; Sanchez et al., 2015). Instead, human sarcomere length estimation (achieved by dividing GM measured fascicle length for a fixed sarcomere number) in dynamic contractions provided an indirect measure of sarcomere operating range during squat jump, countermovement jump, and DJ (Fukashiro et al., 2005, 2006; Kurokawa et al., 2003). The results of these studies showed that sarcomeres operate in the ascending limb of their length-tension (L-T) relationship in all types of jumps, and particularly so in DJ.
However, most of the available observations on sarcomere and muscle fascicle behavior were made in condition of constant gravity. Thus, in order to understand how sarcomere and muscle fascicle length are regulated in variable gravity conditions, we performed experiments in a parabolic flight, involving variable gravity levels, ranging from about zero-g to about double the Earth’s gravity (1 g; Waldvogel et al., 2021).
Specifically, the aims of the present study were as follows:
1. To investigate the ability of the neuromuscular system in regulating fascicle length in response to conditions of variable gravity.
2. To estimate sarcomere operative length in the different DJ phases, in order to calculate its theoretical force production and its possible modulation in conditions of variable gravity.
We hypothesized that muscle fascicles would be differentially regulated in different gravity conditions compared to 1 g, particularly in anticipation of landing and re-bouncing in unknown gravity levels. In addition, we hypothesized that sarcomeres would operate in the upper part of the ascending limb of their L-T relationship, possibly lengthening during the braking phase (especially in hyper-gravity) while operating quasi-isometrically in 1 g.
KW  - parabolic flight
KW  - drop jump
KW  - hypo-gravity
KW  - hyper-gravity
KW  - sarcomere operating length
Y1  - 2021
U6  - http://dx.doi.org/10.3389/fphys.2021.714655
SN  - 1664-042X
VL  - 12
PB  - Frontiers Research Foundation
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Werkhausen, Amelie
A1  - Willwacher, Steffen
A1  - Albracht, Kirsten
T1  - Medial gastrocnemius muscle fascicles shorten throughout stance during sprint acceleration
JF  - Scandinavian Journal of Medicine & Science in Sports
N2  - The compliant nature of distal limb muscle-tendon units is traditionally considered suboptimal in explosive movements when positive joint work is required. However, during accelerative running, ankle joint net mechanical work is positive. Therefore, this study aims to investigate how plantar flexor muscle-tendon behavior is modulated during fast accelerations. Eleven female sprinters performed maximum sprint accelerations from starting blocks, while gastrocnemius muscle fascicle lengths were estimated using ultrasonography. We combined motion analysis and ground reaction force measurements to assess lower limb joint kinematics and kinetics, and to estimate gastrocnemius muscle-tendon unit length during the first two acceleration steps. Outcome variables were resampled to the stance phase and averaged across three to five trials. Relevant scalars were extracted and analyzed using one-sample and two-sample t-tests, and vector trajectories were compared using statistical parametric mapping. We found that an uncoupling of muscle fascicle behavior from muscle-tendon unit behavior is effectively used to produce net positive mechanical work at the joint during maximum sprint acceleration. Muscle fascicles shortened throughout the first and second steps, while shortening occurred earlier during the first step, where negative joint work was lower compared with the second step. Elastic strain energy may be stored during dorsiflexion after touchdown since fascicles did not lengthen at the same time to dissipate energy. Thus, net positive work generation is accommodated by the reuse of elastic strain energy along with positive gastrocnemius fascicle work. Our results show a mechanism of how muscles with high in-series compliance can contribute to net positive joint work.
KW  - locomotion
KW  - muscle mechanics
KW  - running
KW  - sprint start
KW  - ultrasonography
Y1  - 2021
U6  - http://dx.doi.org/10.1111/sms.13956
SN  - 0905-7188 (Druckausgabe)
SN  - 1600-0838 (Onlineausgabe)
VL  - 31
IS  - 7
SP  - 1471
EP  - 1480
PB  - Wiley-Blackwell
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Richter, Charlotte
A1  - Braunstein, Björn
A1  - Stäudle, Benjamin
A1  - Attias, Julia
A1  - Süss, Alexander
A1  - Weber, Tobias
A1  - Mileva, Katya N.
A1  - Rittweger, Jörn
A1  - Green, David A.
A1  - Albracht, Kirsten
T1  - Gastrocnemius medialis contractile behavior during running differs between simulated Lunar and Martian gravities
JF  - Scientific reports
N2  - The international partnership of space agencies has agreed to proceed forward to the Moon sustainably. Activities on the Lunar surface (0.16 g) will allow crewmembers to advance the exploration skills needed when expanding human presence to Mars (0.38 g). Whilst data from actual hypogravity activities are limited to the Apollo missions, simulation studies have indicated that ground reaction forces, mechanical work, muscle activation, and joint angles decrease with declining gravity level. However, these alterations in locomotion biomechanics do not necessarily scale to the gravity level, the reduction in gastrocnemius medialis activation even appears to level off around 0.2 g, while muscle activation pattern remains similar. Thus, it is difficult to predict whether gastrocnemius medialis contractile behavior during running on Moon will basically be the same as on Mars. Therefore, this study investigated lower limb joint kinematics and gastrocnemius medialis behavior during running at 1 g, simulated Martian gravity, and simulated Lunar gravity on the vertical treadmill facility. The results indicate that hypogravity-induced alterations in joint kinematics and contractile behavior still persist between simulated running on the Moon and Mars. This contrasts with the concept of a ceiling effect and should be carefully considered when evaluating exercise prescriptions and the transferability of locomotion practiced in Lunar gravity to Martian gravity.
KW  - Bone quality and biomechanics
KW  - Environmental impact
KW  - Skeletal muscle
KW  - Tendons
KW  - Ultrasound
Y1  - 2021
U6  - http://dx.doi.org/10.1038/s41598-021-00527-9
SN  - 2045-2322
N1  - Corresponding author: Charlotte Richter
VL  - 11
IS  - Article number: 22555
PB  - Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Richter, Charlotte
A1  - Braunstein, Bjoern
A1  - Stäudle, Benjamin
A1  - Attias, Julia
A1  - Suess, Alexander
A1  - Weber, Tobias
A1  - Mileva, Katja N.
A1  - Rittweger, Joern
A1  - Green, David A.
A1  - Albracht, Kirsten
T1  - Gastrocnemius medialis contractile behavior is preserved during 30% body weight supported gait training
JF  - Frontiers in Sports and Active Living
N2  - 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.
KW  - AlterG
KW  - rehabilitation
KW  - gait
KW  - walking
KW  - ultrasound imaging
KW  - series elastic element behavior
KW  - muscle fascicle behavior
KW  - unloading
Y1  - 2021
U6  - http://dx.doi.org/10.3389/fspor.2020.614559
SN  - 2624-9367
VL  - 2021
IS  - 2
PB  - Frontiers
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Akimbekov, Nuraly S.
A1  - Digel, Ilya
A1  - Tastambek, Kuanysh T.
A1  - Sherelkhan, Dinara K.
A1  - Jussupova, Dariya B.
A1  - Altynbay, Nazym P.
T1  - Low-rank coal as a source of humic substances for soil amendment and fertility management
JF  - Agriculture
N2  - 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.
KW  - soil remediation
KW  - crop yield
KW  - soil health
KW  - soil amendment
KW  - low-rank coal
Y1  - 2021
U6  - http://dx.doi.org/10.3390/agriculture11121261
SN  - 2077-0472
N1  - This article belongs to the Special Issue "From Waste to Fertilizer in Sustainable Agriculture"
VL  - 11
IS  - 12
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Richter, Charlotte
A1  - Braunstein, Bjoern
A1  - Staeudle, Benjamin
A1  - Attias, Julia
A1  - Suess, Alexander
A1  - Weber, Tobias
A1  - Mileva, Katya N.
A1  - Rittweger, Joern
A1  - Green, David A.
A1  - Albracht, Kirsten
T1  - Contractile behavior of the gastrocnemius medialis muscle during running in simulated hypogravity
JF  - npj Microgravity
N2  - Vigorous exercise countermeasures in microgravity can largely attenuate muscular degeneration, albeit the extent of applied loading is key for the extent of muscle wasting. Running on the International Space Station is usually performed with maximum loads of 70% body weight (0.7 g). However, it has not been investigated how the reduced musculoskeletal loading affects muscle and series elastic element dynamics, and thereby force and power generation. Therefore, this study examined the effects of running on the vertical treadmill facility, a ground-based analog, at simulated 0.7 g on gastrocnemius medialis contractile behavior. The results reveal that fascicle−series elastic element behavior differs between simulated hypogravity and 1 g running. Whilst shorter peak series elastic element lengths at simulated 0.7 g appear to be the result of lower muscular and gravitational forces acting on it, increased fascicle lengths and decreased velocities could not be anticipated, but may inform the development of optimized running training in hypogravity. However, whether the alterations in contractile behavior precipitate musculoskeletal degeneration warrants further study.
Y1  - 2021
U6  - http://dx.doi.org/10.1038/s41526-021-00155-7
SN  - 2373-8065
N1  - Corresponding author: Charlotte Richter
VL  - 7
IS  - Article number: 32
PB  - Springer Nature
CY  - New York
ER  - 
TY  - JOUR
A1  - Albanna, Walid
A1  - Conzen, Catharina
A1  - Weiss, Miriam
A1  - Seyfried, Katharina
A1  - Kotliar, Konstantin
A1  - Schmidt, Tobias Philip
A1  - Kuerten, David
A1  - Hescheler, Jürgen
A1  - Bruecken, Anne
A1  - Schmidt-Trucksäss, Arno
A1  - Neumaier, Felix
A1  - Wiesmann, Martin
A1  - Clusmann, Hans
A1  - Schubert, Gerrit Alexander
T1  - Non-invasive assessment of neurovascular coupling after aneurysmal subarachnoid hemorrhage: a prospective observational trial using retinal vessel analysis
JF  - Frontiers in Neurology
N2  - 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.
Y1  - 2021
U6  - http://dx.doi.org/10.3389/fneur.2021.690183
SN  - 1664-2295
VL  - 12
IS  - 12
SP  - 1
EP  - 15
ER  - 
TY  - JOUR
A1  - Kuerten, David
A1  - Kotliar, Konstantin
A1  - Fuest, Matthias
A1  - Walter, Peter
A1  - Hollstein, Muriel
A1  - Plange, Niklas
ED  - Neri, Piergiorgio
T1  - Does hemispheric vascular regulation differ significantly in glaucoma patients with altitudinal visual field asymmetry? A single-center, prospective study
JF  - International Ophthalmology
N2  - Purpose Vascular risk factors and ocular perfusion are heatedly discussed in the pathogenesis of glaucoma. The retinal vessel analyzer (RVA, IMEDOS Systems, Germany) allows noninvasive measurement of retinal vessel regulation. Significant differences especially in the veins between healthy subjects and patients suffering from glaucoma were previously reported. In this pilot-study we investigated if localized vascular regulation is altered in glaucoma patients with altitudinal visual field defect asymmetry. Methods 15 eyes of 12 glaucoma patients with advanced altitudinal visual field defect asymmetry were included. The mean defect was calculated for each hemisphere separately (-20.99 ± 10.49 pro- found hemispheric visual field defect vs -7.36 ± 3.97 dB less profound hemisphere). After pupil dilation, RVA measurements of retinal arteries and veins were conducted using the standard protocol. The superior and inferior retinal vessel reactivity were measured consecutively in each eye. Results Significant differences were recorded in venous vessel constriction after flicker light stimulation and overall amplitude of the reaction (p \ 0.04 and p \ 0.02 respectively) in-between the hemispheres spheres. Vessel reaction was higher in the hemisphere corresponding to the more advanced visual field defect. Arterial diameters reacted similarly, failing to reach statistical significance. Conclusion Localized retinal vessel regulation is significantly altered in glaucoma patients with asymmetri altitudinal visual field defects. Veins supplying the hemisphere concordant to a less profound visual field defect show diminished diameter changes. Vascular dysregulation might be particularly important in early glaucoma stages prior to a significant visual field defect.
KW  - Glaucoma
KW  - Visual field asymmetry
KW  - Ocular blood flow
KW  - RVA
KW  - Vascular response
Y1  - 2021
SN  - 1573-2630
U6  - http://dx.doi.org/10.1007/s10792-021-01876-0
VL  - 41
IS  - 41
SP  - 3109
EP  - 3119
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Kezerashvili, Roman Ya
A1  - Dachwald, Bernd
T1  - Preface: Solar sailing: Concepts, technology, and missions II
JF  - Advances in Space Research
Y1  - 2021
U6  - http://dx.doi.org/10.1016/j.asr.2021.01.037
SN  - 0273-1177
VL  - 67
IS  - 9
SP  - 2559
EP  - 2560
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Spietz, Peter
A1  - Spröwitz, Tom
A1  - Seefeldt, Patric
A1  - Grundmann, Jan Thimo
A1  - Jahnke, Rico
A1  - Mikschl, Tobias
A1  - Mikulz, Eugen
A1  - Montenegro, Sergio
A1  - Reershemius, Siebo
A1  - Renger, Thomas
A1  - Ruffer, Michael
A1  - Sasaki, Kaname
A1  - Sznajder, Maciej
A1  - Tóth, Norbert
A1  - Ceriotti, Matteo
A1  - Dachwald, Bernd
A1  - Macdonald, Malcolm
A1  - McInnes, Colin
A1  - Seboldt, Wolfgang
A1  - Quantius, Dominik
A1  - Bauer, Waldemar
A1  - Wiedemann, Carsten
A1  - Grimm, Christian D.
A1  - Hercik, David
A1  - Ho, Tra-Mi
A1  - Lange, Caroline
A1  - Schmitz, Nicole
T1  - Paths not taken – The Gossamer roadmap’s other options
JF  - Advances in Space Research
KW  - Solar sail
KW  - Small spacecraft
KW  - DLR-ESTEC GOSSAMER roadmap for solar sailing
KW  - GOSSAMER-1
Y1  - 2021
U6  - http://dx.doi.org/10.1016/j.asr.2021.01.044
SN  - 0273-1177
VL  - 67
IS  - 9
SP  - 2912
EP  - 2956
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - German, Laura
A1  - Mikucki, Jill A.
A1  - Welch, Susan A.
A1  - Welch, Kathleen A.
A1  - Lutton, Anthony
A1  - Dachwald, Bernd
A1  - Kowalski, Julia
A1  - Heinen, Dirk
A1  - Feldmann, Marco
A1  - Francke, Gero
A1  - Espe, Clemens
A1  - Lyons, W. Berry
T1  - Validation of sampling antarctic subglacial hypersaline waters with an electrothermal ice melting probe (IceMole) for environmental analytical geochemistry
JF  - International Journal of Environmental Analytical Chemistry
N2  - 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.
Y1  - 2021
U6  - http://dx.doi.org/10.1080/03067319.2019.1704750
SN  - 0306-7319
VL  - 101
IS  - 15
SP  - 2654
EP  - 2667
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Heiligers, Jeannette
A1  - Schoutetens, Frederic
A1  - Dachwald, Bernd
T1  - Photon-sail equilibria in the alpha centauri system
JF  - Journal of Guidance, Control, and Dynamics
Y1  - 2021
U6  - http://dx.doi.org/10.2514/1.G005446
SN  - 1533-3884
SN  - 0731-5090
SN  - 0162-3192
VL  - 44
IS  - 5
SP  - 1053
EP  - 1061
ER  - 
TY  - JOUR
A1  - Hunker, Jan L.
A1  - Gossmann, Matthias
A1  - Raman, Aravind Hariharan
A1  - Linder, Peter
T1  - Artificial neural networks in cardiac safety assessment: Classification of chemotherapeutic compound effects on hiPSC-derived cardiomyocyte contractility
JF  - Journal of Pharmacological and Toxicological Methods
Y1  - 2021
U6  - http://dx.doi.org/10.1016/j.vascn.2021.107044
SN  - 1056-8719
VL  - 111
IS  - Article number 107044
PB  - Elsevier
CY  - New York
ER  - 
TY  - JOUR
A1  - Temiz Artmann, Aysegül
A1  - Kurulgan demirci, Eylem
A1  - Fırat, Ipek Seda
A1  - Oflaz, Hakan
A1  - Artmann, Gerhard
T1  - Recombinant activated protein C (rhAPC) affects lipopolysaccharide-induced mechanical compliance changes and beat frequency of mESC-derived cardiomyocyte monolayers
JF  - SHOCK
KW  - Septic cardiomyopathy
KW  - LPS
KW  - cardiomyocyte biomechanics
KW  - CellDrum
KW  - actin cytoskeleton
Y1  - 2021
U6  - http://dx.doi.org/10.1097/SHK.0000000000001845
SN  - 1540-0514
PB  - Wolters Kluwer
CY  - Köln
ER  - 
TY  - JOUR
A1  - Heinke, Lars N.
A1  - Knicker, Axel J.
A1  - Albracht, Kirsten
T1  - Test-retest reliability of the internal shoulder rotator muscles' stretch reflex in healthy men
JF  - Journal of Electromyography and Kinesiology
N2  - Until now the reproducibility of the short latency stretch reflex of the internal rotator muscles of the glenohumeral joint has not been identified. Twenty-three healthy male participants performed three sets of external shoulder rotation stretches with various pre-activation levels on two different dates of measurement to assess test-retest reliability. All stretches were applied with a dynamometer acceleration of 104°/s2 and a velocity of 150°/s. Electromyographical response was measured via surface EMG. Reflex latencies showed a pre-activation effect (ƞ2 = 0,355). ICC ranged from 0,735 to 0,909 indicating an overall “good” relative reliability. SRD 95% lay between ±7,0 to ±12,3 ms.. The reflex gain showed overall poor test-retest reproducibility. The chosen methodological approach presented a suitable test protocol for shoulder muscles stretch reflex latency evaluation. A proof-of-concept study to validate the presented methodical approach in shoulder involvement including subjects with clinically relevant conditions is recommended.
KW  - stretch reflex
KW  - shoulder
KW  - test-retest reliability
KW  - intraclass correlation coefficient
KW  - standard error of measurement
Y1  - 2021
U6  - http://dx.doi.org/10.1016/j.jelekin.2021.102611
SN  - 1050-6411
VL  - 62
IS  - Article 102611
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Alexyuk, Madina
A1  - Bogoyavlenskiy, Andrey
A1  - Alexyuk, Pavel
A1  - Moldakhanov, Yergali
A1  - Berezin, Vladimir
A1  - Digel, Ilya
T1  - Epipelagic microbiome of the Small Aral Sea: Metagenomic structure and ecological diversity
JF  - MicrobiologyOpen
N2  - Microbial diversity studies regarding the aquatic communities that experienced or are experiencing environmental problems are essential for the comprehension of the remediation dynamics. In this pilot study, we present data on the phylogenetic and ecological structure of microorganisms from epipelagic water samples collected in the Small Aral Sea (SAS). The raw data were generated by massive parallel sequencing using the shotgun approach. As expected, most of the identified DNA sequences belonged to Terrabacteria and Actinobacteria (40% and 37% of the total reads, respectively). The occurrence of Deinococcus-Thermus, Armatimonadetes, Chloroflexi in the epipelagic SAS waters was less anticipated. Surprising was also the detection of sequences, which are characteristic for strict anaerobes—Ignavibacteria, hydrogen-oxidizing bacteria, and archaeal methanogenic species. We suppose that the observed very broad range of phylogenetic and ecological features displayed by the SAS reads demonstrates a more intensive mixing of water masses originating from diverse ecological niches of the Aral-Syr Darya River basin than presumed before.
KW  - ecological structure
KW  - metagenomics
KW  - microbial diversity
KW  - shotgun sequencing
KW  - Small Aral Sea
Y1  - 2021
U6  - http://dx.doi.org/10.1002/mbo3.1142
SN  - 2045-8827
VL  - 10
IS  - 1
SP  - 1
EP  - 10
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Staat, Manfred
T1  - An extension strain type Mohr–Coulomb criterion
JF  - Rock mechanics and rock engineering
N2  - Extension fractures are typical for the deformation under low or no confining pressure. They can be explained by a phenomenological extension strain failure criterion. In the past, a simple empirical criterion for fracture initiation in brittle rock has been developed. In this article, it is shown that the simple extension strain criterion makes unrealistic strength predictions in biaxial compression and tension. To overcome this major limitation, a new extension strain criterion is proposed by adding a weighted principal shear component to the simple criterion. The shear weight is chosen, such that the enriched extension strain criterion represents the same failure surface as the Mohr–Coulomb (MC) criterion. Thus, the MC criterion has been derived as an extension strain criterion predicting extension failure modes, which are unexpected in the classical understanding of the failure of cohesive-frictional materials. In progressive damage of rock, the most likely fracture direction is orthogonal to the maximum extension strain leading to dilatancy. The enriched extension strain criterion is proposed as a threshold surface for crack initiation CI and crack damage CD and as a failure surface at peak stress CP. Different from compressive loading, tensile loading requires only a limited number of critical cracks to cause failure. Therefore, for tensile stresses, the failure criteria must be modified somehow, possibly by a cut-off corresponding to the CI stress. Examples show that the enriched extension strain criterion predicts much lower volumes of damaged rock mass compared to the simple extension strain criterion.
Y1  - 2021
U6  - http://dx.doi.org/10.1007/s00603-021-02608-7
SN  - 1434-453X
N1  - Corresponding author: Manfred Staat
VL  - 54
IS  - 12
SP  - 6207
EP  - 6233
PB  - Springer Nature
CY  - Cham
ER  - 
TY  - JOUR
A1  - Hackl, Michael
A1  - Buess, Eduard
A1  - Kammerlohr, Sandra
A1  - Nacov, Julia
A1  - Staat, Manfred
A1  - Leschinger, Tim
A1  - Müller, Lars P.
A1  - Wegmann, Kilian
T1  - A "comma sign"-directed subscapularis repair in anterosuperior rotator cuff tears yields biomechanical advantages in a cadaveric model
JF  - The american journal of sports medicine
N2  - 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.
Y1  - 2021
U6  - http://dx.doi.org/10.1177/03635465211031506
SN  - 1552-3365
SN  - 0363-5465
VL  - 49
IS  - 12
SP  - 3212
EP  - 3217
PB  - Sage
CY  - London
ER  - 
TY  - JOUR
A1  - Brockhaus, Moritz K.
A1  - Behbahani, Mehdi
A1  - Muris, Farina
A1  - Jansen, Sebastian V.
A1  - Schmitz- Rode, Thomas
A1  - Steinseifer, Ulrich
A1  - Clauser, Johanna C.
T1  - In vitro thrombogenicity testing of pulsatile mechanical circulatory support systems: Design and proof-of-concept
JF  - Artificial Organs
N2  - Thrombogenic complications are a main issue in mechanical circulatory support (MCS). There is no validated in vitro method available to quantitatively assess the thrombogenic performance of pulsatile MCS devices under realistic hemodynamic conditions. The aim of this study is to propose a method to evaluate the thrombogenic potential of new designs without the use of complex in-vivo trials. This study presents a novel in vitro method for reproducible thrombogenicity testing of pulsatile MCS systems using low molecular weight heparinized porcine blood. Blood parameters are continuously measured with full blood thromboelastometry (ROTEM; EXTEM, FIBTEM and a custom-made analysis HEPNATEM). Thrombus formation is optically observed after four hours of testing. The results of three experiments are presented each with two parallel loops. The area of thrombus formation inside the MCS device was reproducible. The implantation of a filter inside the loop catches embolizing thrombi without a measurable increase of platelet activation, allowing conclusions of the place of origin of thrombi inside the device. EXTEM and FIBTEM parameters such as clotting velocity (α) and maximum clot firmness (MCF) show a total decrease by around 6% with a characteristic kink after 180 minutes. HEPNATEM α and MCF rise within the first 180 minutes indicate a continuously increasing activation level of coagulation. After 180 minutes, the consumption of clotting factors prevails, resulting in a decrease of α and MCF. With the designed mock loop and the presented protocol we are able to identify thrombogenic hot spots inside a pulsatile pump and characterize their thrombogenic potential.
Y1  - 2021
U6  - http://dx.doi.org/10.1111/aor.14046
SN  - 1525-1594
VL  - 45
IS  - 12
SP  - 1513
EP  - 1521
PB  - Wiley
CY  - Weinheim
ER  -