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Contact force

Matej Voglar, Jeffrey Wamerdam, Idsart Kingma, Nejc Sarabon, Jaap H van Dieën
The goal of the present study was to determine the effects of prolonged, intermittent flexion on trunk neuromuscular control. Furthermore, the potential beneficial effects of passive upper body support during flexion were investigated. Twenty one healthy young volunteers participated during two separate visits in which they performed 1 hour of intermittent 60 seconds flexion and 30 seconds rest cycles. Flexion was set at 80% lumbar flexion and was performed with or without upper body support. Before and after intermittent flexion exposure, lumbar range of motion was measured using inertial measurement units and trunk stability was assessed during perturbations applied in the forward direction with a force controlled actuator...
2016: PloS One
Nicola Giovanelli, Paolo Taboga, Stefano Lazzer
PURPOSE: To investigate changes in running mechanics during a six hours running race. METHODS: Twelve ultra-runners (age: 41.9±5.8 years; body mass: 68.3±12.6 kg; stature: 1.72±0.09 m) were asked to run as many 874 m flat loops as possible in six hours. Running speed, contact (tc) and aerial (ta) times were measured in the first lap and every 30±2 minutes during the race. Peak vertical ground reaction force (Fmax), stride length (SL), vertical downward displacement of the centre of mass (Δz), leg length change (ΔL), vertical (kvert) and leg (kleg) stiffness were then estimated...
September 26, 2016: International Journal of Sports Physiology and Performance
Philipp Leinen, Matthew F B Green, Taner Esat, Christian Wagner, F Stefan Tautz, Ruslan Temirov
Considering organic molecules as the functional building blocks of future nanoscale technology, the question of how to arrange and assemble such building blocks in a bottom-up approach is still open. The scanning probe microscope (SPM) could be a tool of choice; however, SPM-based manipulation was until recently limited to two dimensions (2D). Binding the SPM tip to a molecule at a well-defined position opens an opportunity of controlled manipulation in 3D space. Unfortunately, 3D manipulation is largely incompatible with the typical 2D-paradigm of viewing and generating SPM data on a computer...
October 2, 2016: Journal of Visualized Experiments: JoVE
Vi Khanh Truong, Miljan Stefanovic, Shane Maclaughlin, Mark Tobin, Jitraporn Vongsvivut, Mohammad Al Kobaisi, Russell J Crawford, Elena P Ivanova
Corrosion of metallic surfaces is prevalent in the environment and is of great concern in many areas, including the military, transport, aviation, building and food industries, amongst others. Polyester and coatings containing both polyester and silica nanoparticles (SiO2NPs) have been widely used to protect steel substrata from corrosion. In this study, we utilized X-ray photoelectron spectroscopy, attenuated total reflection infrared micro-spectroscopy, water contact angle measurements, optical profiling and atomic force microscopy to provide an insight into how exposure to sunlight can cause changes in the micro- and nanoscale integrity of the coatings...
October 11, 2016: Journal of Visualized Experiments: JoVE
A Priezzhev, K Lee
Laser trapping and manipulation of blood cells without mechanical contact have become feasible with implication of laser tweezers. They open up new horizons for the hemorheologic researches, offer new possibilities for studying live cells interactions on individual cell level under the influence of different endogenous and exogenous factors. The operation principle of laser tweezers is based on the property of strongly focused laser beam to act on a dielectric microparticle located in the vicinity of the beam waist with a force that drives the particle to the equilibrium location and holds it there...
October 21, 2016: Clinical Hemorheology and Microcirculation
Hongwei Yao, Myungwoon Lee, Shu Y Liao, Mei Hong
The fusion peptide (FP) and transmembrane domain (TMD) of viral fusion proteins play important roles during virus-cell membrane fusion, by inducing membrane curvature and transient dehydration. The structure of the water-soluble ectodomain of viral fusion proteins has been extensively studied crystallographically, but the structures of the FP and TMD bound to phospholipid membranes are not well understood. We recently investigated the conformations and lipid interactions of the separate FP and TMD peptides of the parainfluenza virus 5 (PIV5) fusion protein F using solid-state NMR...
October 21, 2016: Biochemistry
Emily Meike, S M Howell, M L Hull
PURPOSE: After reconstructing a torn ACL with a soft tissue allograft, the long-term healing process of graft maturation following the short-term healing process of graft incorporation into the bone tunnels might lead to recurring instability and concomitant decreases in the activity level, function, and patient satisfaction. Relying on roentgen stereophotogrammetric analysis (RSA), the primary purpose was to determine whether anterior laxity increased and whether patient-reported outcomes declined between 1 and 7 years for a particular graft construct, surgical technique, and rehabilitation programme...
October 20, 2016: Knee Surgery, Sports Traumatology, Arthroscopy: Official Journal of the ESSKA
Joshua Giltinan, Eric Diller, Metin Sitti
At the sub-millimeter scale, capillary forces enable robust and reversible adhesion between biological organisms and varied substrates. Current human-engineered mobile untethered micromanipulation systems rely on forces which scale poorly or utilize gripper-part designs that promote manipulation. Capillary forces, alternatively, are dependent upon the surface chemistry (which is scale independent) and contact perimeter, which conforms to the part surface. We report a mobile capillary microgripper that is able to pick and place parts of various materials and geometries, and is thus ideal for microassembly tasks that cannot be accomplished by large tethered manipulators...
October 21, 2016: Lab on a Chip
Meta N Eek, Kate Himmelmann
Spasticity and muscle weakness is common in children with cerebral palsy (CP). Spasticity can be treated with botulinum neurotoxin-A (BoNT-A), but this drug has also been reported to induce muscle weakness. Our purpose was to describe the effect on muscle strength in the lower extremities after BoNT-A injections in children with CP. A secondary aim was to relate the effect of BoNT-A to gait pattern and range of motion. Twenty children with spastic CP were included in the study, 8 girls and 12 boys (mean age 7...
2016: Frontiers in Human Neuroscience
Ryo Suzuki, Kohta Ito, Taeyong Lee, Naomichi Ogihara
Accurate identification of the material properties of the plantar soft tissue is important for computer-aided analysis of foot pathologies and design of therapeutic footwear interventions based on subject-specific models of the foot. However, parameter identification of the hyperelastic material properties of plantar soft tissues usually requires an inverse finite element analysis due to the lack of a practical contact model of the indentation test. In the present study, we derive an analytical contact model of a spherical indentation test in order to directly estimate the material properties of the plantar soft tissue...
September 22, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Zhizhao Che, Panagiotis E Theodorakis
Surface nanobubbles are stable gaseous phases in liquids that form on solid substrates. While their existence has been confirmed, there are many open questions related to their formation and dissolution processes along with their structures and properties, which are difficult to investigate experimentally. To address these issues, we carried out molecular dynamics simulations based on atomistic force fields for systems comprised of water, air (N2 and O2), and a Highly Oriented Pyrolytic Graphite (HOPG) substrate...
October 14, 2016: Journal of Colloid and Interface Science
Fengjing Wu, Xiaojuan Liu, Chaktong Au
The polyamide reverse osmosis (RO) membranes were prepared through interfacial polymerization of m-phenylenediamine (MPD) and trimesoyl chloride (TMC). The use of dimethyl sulfoxide (DMSO) and glycerol as additives for the formation of thin-film composite (TFC) was investigated. We studied the effect of DMSO and glycerol addition on membrane property and RO performance. Microscopic morphology was examined by atomic force microscopy and scanning electron microscopy. The surface hydrophilicity was characterized on the basis of water contact angle and surface solid-liquid interfacial free energy (-ΔGSL)...
October 2016: Water Science and Technology: a Journal of the International Association on Water Pollution Research
Shanshan Guo, Xiaoying Zhu, Min Li, Liya Shi, June Lay Ting Ong, Dominik Jańczewski, Koon Gee Neoh
Surface charge and wettability, the two prominent physical factors governing protein adsorption and cell adhesion, have been extensively investigated in the literature. However, a comparison between these driving forces in terms of their independent and cooperative effects in affecting adhesion is rarely explored on a systematic and quantitative level. Herein, we formulate a protocol which features two-dimensional control over both surface charge and wettability with limited cross parameter influence. This strategy is implemented by controlling both the polyion charge density in the layer-by-layer (LbL) assembly process and the polyion side chain chemical structures...
October 20, 2016: ACS Applied Materials & Interfaces
Y Liu, L Huang, H Ye, X Lv
Interferon regulatory factor-7 (IRF-7) is involved in pulmonary infection and pneumonia. Here, a synthetic strategy that combined quantitative structure-activity relationship (QSAR)-based virtual screening and in vitro binding assay was described to identify new and potent mediator ligands of IRF-7 from natural products. In the procedure, a QSAR scoring function was developed and validated using Gaussian process (GP) regression and a structure-based set of protein-ligand affinity data. By integrating hotspot pocket prediction, pharmacokinetics profile analysis and molecular docking calculations, the scoring function was successfully applied to virtual screening against a large library of structurally diverse, drug-like natural products...
October 20, 2016: SAR and QSAR in Environmental Research
Jiaqing Zhuang, Qi-Jun Sun, Ye Zhou, Suting Han, Li Zhou, Yan Yan, Haiyan Peng, Shishir Venkatesh, Wei Wu, Robert Kwok-Yiu Li, Vellaisamy A L Roy
Previous investigations on rare-earth oxides (REOs) reveal their high possibility as dielectric films in electronic devices, while complicated physical methods impede their developments and applications. Herein, we report a facile route to fabricate 16 REOs thin insulating films through a general solution process and their applications in low-voltage thin-film transistors as dielectrics. The formation and properties of REOs thin films are analyzed by atomic force microscopy (AFM), X-ray diffraction (XRD), spectroscopic ellipsometry, water contact angle measurement, X-ray photoemission spectroscopy (XPS) and electrical characterizations, respectively...
October 20, 2016: ACS Applied Materials & Interfaces
Pablo Arturo Fernández Garrillo, Lukasz Borowik, Florent Caffy, Renaud Demadrille, Benjamin Grevin
Investigating the photo-carrier dynamics in nanostructured and heterogeneous energy materials is of crucial importance from both fundamental and technological points of view. Here, we demonstrate how non-contact atomic force microscopy combined with Kelvin Probe Force Microscopy under frequency modulated illumination can be used to simultaneously image the surface photo-potential dynamics at different timescales with a sub-10 nm lateral resolution. The basic principle of the method consists in the acquisition of spectroscopic curves of the surface potential as a function of the illumination frequency modulation on a two dimensional grid...
October 20, 2016: ACS Applied Materials & Interfaces
Curtis D Westersund, Jeffrey Scholten, Raymond J Turner
OBJECTIVE: Clinical observation and anecdotal reports suggest changes can occur to dental occlusion following intervention with the National Upper Cervical Chiropractic Association (NUCCA) procedure. This case controlled study discerned if occlusion changes are measurable using a dental force plate (T-Scan®) following an adjustment to the craniocervical junction (CCJ). METHODS: A degree of case control was established by active patients being assessed twice prior to and following intervention...
October 20, 2016: Cranio: the Journal of Craniomandibular Practice
Benjamin Scharnweber, Frederic Adjami, Gabriele Schuster, Stefan Kopp, Jörg Natrup, Christina Erbe, Daniela Ohlendorf
OBJECTIVE: The number of studies investigating correlations between the temporomandibular system and body posture, postural control or plantar pressure distribution is continuously increasing. If a connection can be found, it is often of minor influence or for only a single parameter. However, small subject groups are critical. This study was conducted to define correlations between dental parameters, postural control and plantar pressure distribution in healthy males. METHODS: In this study, 87 male subjects with an average age of 25...
October 20, 2016: Cranio: the Journal of Craniomandibular Practice
Nir Kampf, Chunxian Wu, Yilin Wang, Jacob Klein
The surface structure of the trimeric surfactant tri(dodecyldimethylammonioacetoxy)-diethyltriamine trichloride (DTAD) on mica, and the interactions between two such DTAD-coated surfaces were determined using atomic force microscopy and a surface force balance. In an aqueous solution of 3 mM, five times the critical aggregation concentration (CAC), the surfaces are coated with worm-like micelles or hemi-micelles and larger (ca. 80 nm) bilayer vesicles. Repulsive normal interactions between the surfaces indicate a net surface charge and a solution concentration of ions close to that expected from the CAC...
October 19, 2016: Langmuir: the ACS Journal of Surfaces and Colloids
Jacques Pécréaux, Stefanie Redemann, Zahraa Alayan, Benjamin Mercat, Sylvain Pastezeur, Carlos Garzon-Coral, Anthony A Hyman, Jonathon Howard
Precise positioning of the mitotic spindle is important for specifying the plane of cell division, which in turn determines how the cytoplasmic contents of the mother cell are partitioned into the daughter cells, and how the daughters are positioned within the tissue. During metaphase in the early Caenorhabditis elegans embryo, the spindle is aligned and centered on the anterior-posterior axis by a microtubule-dependent machinery that exerts restoring forces when the spindle is displaced from the center. To investigate the accuracy and stability of centering, we tracked the position and orientation of the mitotic spindle during the first cell division with high temporal and spatial resolution...
October 18, 2016: Biophysical Journal
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