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Contact force

Jana Link, Dimitra Paouneskou, Maria Velkova, Anahita Daryabeigi, Triin Laos, Sara Labella, Consuelo Barroso, Sarai Pacheco Piñol, Alex Montoya, Holger Kramer, Alexander Woglar, Antoine Baudrimont, Sebastian Mathias Markert, Christian Stigloher, Enrique Martinez-Perez, Alexander Dammermann, Manfred Alsheimer, Monique Zetka, Verena Jantsch
Meiotic chromosome movement is important for the pairwise alignment of homologous chromosomes, which is required for correct chromosome segregation. Movement is driven by cytoplasmic forces, transmitted to chromosome ends by nuclear membrane-spanning proteins. In animal cells, lamins form a prominent scaffold at the nuclear periphery, yet the role lamins play in meiotic chromosome movement is unclear. We show that chromosome movement correlates with reduced lamin association with the nuclear rim, which requires lamin phosphorylation at sites analogous to those that open lamina network crosslinks in mitosis...
April 23, 2018: Developmental Cell
Christopher L Hoffman, Nicola J Volstad, Eric C Hans, Brett W Nemke, Peter Muir
OBJECTIVE To develop contact time (ConT) and withers height-normalized relative ConT (ConT*) for force platform gait analysis of dogs. ANIMALS 29 healthy client-owned dogs. PROCEDURES Height at the most dorsal aspect of the shoulders (withers) was measured with a framing square. Dogs were trotted across a force platform at their preferred velocity with controlled acceleration (± 0.5 m/s2 ). Ranges of ConT and ConT* centered on the population mean ConT were created. Variance effects on ground reaction forces (GRFs) for 4 thoracic limb and 4 pelvic limb ConT and associated ConT* ranges were examined...
May 2018: American Journal of Veterinary Research
E O Oviedo-Rondón, P L Mente, C Arellano, B D X Lascelles, A Mitchell
Leg problems have become more frequent in fast-growing turkeys. The objective of this study was to evaluate the effects of common leg defects on kinetic parameters of gait and biomechanical properties of bone. Nine hundred, day-old, male, Large White turkeys were raised in 48 floor pens. At 42 d of age, turkeys were divided into four categories of leg condition as determined by visual evaluation: Normal, Crooked toes, Shaky legs, and Valgus. Fifteen toms were selected from each group and trained to walk on a pressure sensitive walkway...
April 23, 2018: Poultry Science
Ethan Stewart, Thomas Kernozek, Hsien-Te Peng, Brian Wallace
BACKGROUND: This study quantified the peak vertical ground reaction force (VGRF), impulse, and average and instantaneous loading rates developed during bilateral plyometric exercises. METHODS: Fourteen collegiate male athletes performed four different bilateral plyometric exercises within a single testing session. Depth jumps from thirty, sixty and ninety centimeter heights (DJ30, DJ60, and DJ90, respectively), and a two consecutive jump exercise (2CJ), were randomly performed...
April 20, 2018: Journal of Sports Medicine and Physical Fitness
Jim D Darke, Eshan M Dandekar, Arnel L Aguinaldo, Scott J Hazelwood, Stephen M Klisch
Background: Pitching while fatigued and body composition may increase the injury risk in youth and adult pitchers. However, the relationships between game pitch count, biomechanics, and body composition have not been reported for a study group restricted to 9- to 10-year-old athletes. Hypothesis: During a simulated game with 9- to 10-year-old athletes, (1) participants will experience biomechanical signs of fatigue, and (2) shoulder and elbow kinetics will correlate with body mass index (BMI)...
April 2018: Orthopaedic Journal of Sports Medicine
Nathan D Schilaty, Nathaniel A Bates, Christopher V Nagelli, Aaron J Krych, Timothy E Hewett
Background: Female patients sustain noncontact knee ligament injuries at a greater rate compared with their male counterparts. The cause of these differences in the injury rate and the movements that load the ligaments until failure are still under dispute in the literature. Purpose/Hypotheses: This study was designed to determine differences in anterior cruciate ligament (ACL) and medial collateral ligament (MCL) strains between male and female cadaveric specimens during a simulated athletic task...
April 2018: Orthopaedic Journal of Sports Medicine
Shahrouz Amini, Maryam Tadayon, J Q Isaiah Chua, Ali Miserez
The Arthropoda, the largest phylum of the Animal Kingdom, have successfully evolved to survive various ecological constraints under a wide range of environmental conditions. Central to this survival are the structural designs developed in their exoskeletons and their raptorial appendages for protection and hunting. One such example, the pistol shrimp, is a shallow-water crustacean that is well-known for its aggressive hunting behavior, using its snapper claw to trigger the nucleation of cavitation bubbles that strike targets...
April 20, 2018: Acta Biomaterialia
Laila Moreno Ostertag, Xiao Ling, Katrin F Domke, Sapun H Parekh, Markus Valtiner
The surface density of charged sulfonic acid head groups in a perfluorosulfonic acid (PFSA) proton exchange membrane determines the hydrophilicity of the ionic channels and is thus critical for the structuring and transport of water and protons. The mechanism through which the head group density affects the structuring of water and ions is unknown, largely due to experimental challenges in systematically varying the density in an appropriate model system resembling the ionic channels. Here, we present a model system for PFSA membrane ionic channels using self-assembled monolayers with a tunable surface density of sulfonic acid and methyl groups to tune surface hydrophilicity...
April 23, 2018: Physical Chemistry Chemical Physics: PCCP
A Krull, M M Morlock, N E Bishop
Objectives: Taper junctions between modular hip arthroplasty femoral heads and stems fail by wear or corrosion which can be caused by relative motion at their interface. Increasing the assembly force can reduce relative motion and corrosion but may also damage surrounding tissues. The purpose of this study was to determine the effects of increasing the impaction energy and the stiffness of the impactor tool on the stability of the taper junction and on the forces transmitted through the patient's surrounding tissues...
February 2018: Bone & Joint Research
Yan Zhang, Jan Awrejcewicz, Olga Szymanowska, Siqin Shen, Xiaoxue Zhao, Julien S Baker, Yaodong Gu
The internal stress of the human foot enables efficient parametric evaluation of structural and functional impairments associated with foot deformities, such as hallux valgus (HV). However, the status of the internal stress of such a deformed foot remains insufficiently addressed due to the difficulties and limitations of experimental approaches. This study, using finite element (FE) methodology, investigated the influence of severe HV deformity on the metatarsal stress and the metatarsophalangeal (MTP) joint loading during balanced standing...
April 16, 2018: Computers in Biology and Medicine
Munsur Rahman, Mohsen Sharifi Renani, Akin Cil, Antonis P Stylianou
A dynamic musculoskeletal model of the elbow joint in which muscle, ligament, and articular surface contact forces are predicted concurrently would be an ideal tool for patient-specific preoperative planning, computer-aided surgery, and rehabilitation. Existing musculoskeletal elbow joint models have limited clinical applicability because of idealizing the elbow as a mechanical hinge joint or ignoring important soft tissue (e.g., cartilage) contributions. The purpose of this study was to develop a subject-specific anatomically correct musculoskeletal elbow joint model and evaluate it based on experimental kinematics and muscle electromyography measurements...
April 20, 2018: Bioengineering
Nektaria Koursari, Gulraiz Ahmed, Victor M Starov
Equilibrium of droplet on deformable substrates is theoretically investigated and equilibrium profiles of both the droplet and the deformed support are determined. The action of surface forces (disjoining/conjoining pressure) in the vicinity of the apparent three phase contact line is taken into account. At the equilibrium the excess free energy of the system should have a minimum value, which means that both necessary and sufficient conditions of the minimum should be fulfilled. Only in this case the obtained profiled provide the minimum of the excess free energy...
April 20, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Victor W Or, Armando D Estillore, Alexei V Tivanski, Vicki H Grassian
New developments in nanoscale analytical techniques have paved the way for detailed spectroscopic and microscopic measurements of substrate-deposited aerosol particles on a single particle basis. Atomic force microscopy based photothermal infrared (AFM-PTIR) spectroscopy is a technique that combines the nanometer spatial resolution of AFM with the chemical analysis capabilities of vibrational IR spectroscopy. Herein we demonstrate the capability of AFM-PTIR to investigate single and multi-component systems comprised of inorganic salts and organic compounds relevant to the atmosphere...
April 20, 2018: Analyst
Antonios Kouloumpis, Nikolaos Vourdas, Panagiota Zygouri, Nikolaos Chalmpes, Georgia Potsi, Vasilios Kostas, Konstantinos Spyrou, Vassilis N Stathopoulos, Dimitrios Gournis, Petra Rudolf
The scientific and technological potential of graphene's includes the development of light, open 3D hybrid structures with high surface area, tunable pore size and aromatic functionalities. Towards this aim, we describe a scalable and low-cost bottom-up approach that combines self-assembly and Langmuir-Schaefer deposition for the production of fullerene-intercalated graphene oxide hybrids. This method uses graphene oxide (GO) nanosheets as template for the attachment of two types of fullerene derivatives (bromo-fullerenes, C60 Br24 and fullerols, C60 (OH)24 ) in a bi-dimensional arrangement, allowing a layer-by-layer growth with control at nanoscale...
April 12, 2018: Journal of Colloid and Interface Science
Luca Modenese, Erica Montefiori, Anqi Wang, Stefan Wesarg, Marco Viceconti, Claudia Mazzà
The generation of subject-specific musculoskeletal models of the lower limb has become a feasible task thanks to improvements in medical imaging technology and musculoskeletal modelling software. Nevertheless, clinical use of these models in paediatric applications is still limited for what concerns the estimation of muscle and joint contact forces. Aiming to improve the current state of the art, a methodology to generate highly personalized subject-specific musculoskeletal models of the lower limb based on magnetic resonance imaging (MRI) scans was codified as a step-by-step procedure and applied to data from eight juvenile individuals...
March 30, 2018: Journal of Biomechanics
Hulya Sahin, Ilknur Naz
This study aims to compare demographic and clinical characteristics of chronic obstructive pulmonary disease (COPD) patients who complete and fail to complete outpatient pulmonary rehabilitation (PR) program and to determine the reasons for not completing the program. Patients with COPD referred to the PR program were divided into two groups: Those who completed the program were classified as group 1 and those who did not complete were classified as group 2, and their data were compared. Patients who failed to complete the program were contacted through phone and asked why they ceased their participation in the program...
January 1, 2018: Chronic Respiratory Disease
Jabid Quiroga Mendez, Luis Mujica, Rodolfo Villamizar, Magda Ruiz
In this paper, a support stiffness monitoring scheme based on torsional guided waves for detecting loss of rigidity in a support of cylindrical structures is presented. Poor support performance in cylindrical specimens such as a pipeline setup located in a sloping terrain may produce a risky operation condition in terms of the installation integrity and the possibility of human casualties. The effects of changing the contact forces between support and the waveguide have been investigated by considering variations in the load between them...
April 19, 2018: Sensors
Yi-Chung Lin, Jonathan P Walter, Marcus G Pandy
We implemented direct collocation on a full-body neuromusculoskeletal model to calculate muscle forces, ground reaction forces and knee contact loading simultaneously for one cycle of human gait. A data-tracking collocation problem was solved for walking at the normal speed to establish the practicality of incorporating a 3D model of articular contact and a model of foot-ground interaction explicitly in a dynamic optimization simulation. The data-tracking solution then was used as an initial guess to solve predictive collocation problems, where novel patterns of movement were generated for walking at slow and fast speeds, independent of experimental data...
April 18, 2018: Annals of Biomedical Engineering
Zhuo Liang, Xuejun Ren, Tao Zhang, Zhihong Han, Jianzeng Dong, Yunlong Wang
PURPOSE: We assessed conventional and reversed U curve methods for mapping and ablation of RVOT-type VAs. METHODS: Single-center data were reviewed from consecutive cases of symptomatic VAs of RVOT-type origin that were mapped and ablated successfully using conventional method in RVOT (pulmonary artery might be included) from January 2014 to December 2015 (cohort 1, n = 75) or conventional method in RVOT and reversed U curve in PSC (for first ablation attempt) from January 2016 to March 2017 (cohort 2, n = 60)...
April 18, 2018: Journal of Interventional Cardiac Electrophysiology: An International Journal of Arrhythmias and Pacing
Zheyu Liu, Hongyu Lu, Yelong Zheng, Dashuai Tao, Yonggang Meng, Yu Tian
Continuous approaching and detaching displacement usually occurs in an adhesion test. Here, we found a transient adhesion force at the end of a non-fully detached contact. This force occurred when the nominal detaching displacement was less than the traditional quasi-static theory predicted zero force point. The transient adhesion force was ascribed to interfacial adhesion hysteresis, which was caused by the cracking process of the contact and the deformation competition between the sphere and supporting spring...
April 18, 2018: Scientific Reports
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