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Critical torque

Yinfeng Li, Qianling Lin, Daxiang Cui
Graphene annulus possesses special wrinkling phenomenon with wide range of potential applications. Using molecular dynamics simulation, this study concerns the effect of boundary on the mechanical properties of circular and elliptical graphene annuli under circular shearing at inner edge. Both the wrinkle characteristic and torque capacity of annular graphene can be effectively tuned by outer boundary radius and aspect ratio. For circular annulus with fixed inner radius, the critical angle of rotation can be increased by several times without sacrificing its torque capacity by increasing outer boundary radius...
February 13, 2017: Scientific Reports
Keonyoung Oh, Sukyung Park
A local minimum for running energetics has been reported for a specific bending stiffness, implying that shoe stiffness assists in running propulsion. However, the determinant of the metabolic optimum remains unknown. Highly stiff shoes significantly increase the moment arm of the ground reaction force (GRF) and reduce the leverage effect of joint torque at ground push-off. Inspired by previous findings, we hypothesized that the restriction of the natural metatarsophalangeal (MTP) flexion caused by stiffened shoes and the corresponding joint torque changes may reduce the benefit of shoe bending stiffness to running energetics...
January 18, 2017: Journal of Biomechanics
Carlota Mendez Torrecillas, Gavin W Halbert, Dimitrios A Lamprou
It is important during powder granulation to obtain particles of a homogeneous size especially in critical situations such as pharmaceutical manufacture. To date, homogeneity of particle size distribution has been defined by the use of the d50 combined with the span of the particle size distribution, which has been found ineffective for polymodal particle size distributions. This work focuses on demonstrating the limitations of the span parameter to quantify homogeneity and proposes a novel improved metric based on the transformation of a typical particle size distribution curve into a homogeneity factor which can vary from 0 to 100%...
January 16, 2017: International Journal of Pharmaceutics
Alexandre Terrier, Adeliya Latypova, Maika Guillemin, Valérie Parvex, Olivier Guyen
PURPOSE: Constrained devices, standard implants with large heads, and dual mobility systems have become popular options to manage instability after total hip arthroplasty (THA). Clinical results with these options have shown variable success rates and significant higher rates of aseptic loosening and mechanical failures with constrained implants. Literature suggests potential advantages of dual mobility, however little is known about its biomechanics. We present a comparative biomechanical study of a standard implant, a constrained implant, and a dual mobility system...
January 9, 2017: International Orthopaedics
Federico Nessi, Elisa Beretta, Cecilia Gatti, Giancarlo Ferrigno, Elena De Momi
BACKGROUND: Cooperative robotics is receiving greater acceptance because the typical advantages provided by manipulators are combined with an intuitive usage. In particular, hands-on robotics may benefit from the adaptation of the assistant behavior with respect to the activity currently performed by the user. A fast and reliable classification of human activities is required, as well as strategies to smoothly modify the control of the manipulator. In this scenario, gesteme-based motion classification is inadequate because it needs the observation of a wide signal percentage and the definition of a rich vocabulary...
November 2016: Artificial Intelligence in Medicine
Rajesh Singh, R Adhikari
The lack of detailed balance in active colloidal suspensions allows dissipation to determine stationary states. Here we show that slow viscous flow produced by polar or apolar active colloids near plane walls mediates attractive hydrodynamic forces that drive crystallization. Hydrodynamically mediated torques tend to destabilize the crystal but stability can be regained through critical amounts of bottom heaviness or chiral activity. Numerical simulations show that crystallization is not nucleational, as in equilibrium, but is preceded by a spinodal-like instability...
November 25, 2016: Physical Review Letters
Zhuan Qin, Wei-Ting Lin, Shiwei Zhu, Aime T Franco, Jun Liu
: Helicobacter pylori is a bacterial pathogen that can cause many gastrointestinal diseases including ulcers and gastric cancer. A unique chemotaxis-mediated motility is critical for H. pylori to colonize in the human stomach and to establish chronic infection, but the underlying molecular mechanisms are not well understood. Here we employ cryo-electron tomography to reveal detailed structures of the H. pylori cell envelope including the sheathed flagella and chemotaxis arrays. Notably, H...
November 14, 2016: Journal of Bacteriology
Fan Yu, Max Hirschberger, Toshinao Loew, Gang Li, Benjamin J Lawson, Tomoya Asaba, J B Kemper, Tian Liang, Juan Porras, Gregory S Boebinger, John Singleton, Bernhard Keimer, Lu Li, N Phuan Ong
Strong evidence for charge-density correlation in the underdoped phase of the cuprate YBa2Cu3Oy was obtained by NMR and resonant X-ray scattering. The fluctuations were found to be enhanced in strong magnetic fields. Recently, 3D charge-density-wave (CDW) formation with long-range order (LRO) was observed by X-ray diffraction in [Formula: see text] 15 T. To elucidate how the CDW transition impacts the pair condensate, we have used torque magnetization to 45 T and thermal conductivity [Formula: see text] to construct the magnetic phase diagram in untwinned crystals with hole density p = 0...
October 24, 2016: Proceedings of the National Academy of Sciences of the United States of America
Hyunglae Lee, Elliott J Rouse, Hermano Igo Krebs
The human ankle joint plays a critical role during walking and understanding the biomechanical factors that govern ankle behavior and provides fundamental insight into normal and pathologically altered gait. Previous researchers have comprehensively studied ankle joint kinetics and kinematics during many biomechanical tasks, including locomotion; however, only recently have researchers been able to quantify how the mechanical impedance of the ankle varies during walking. The mechanical impedance describes the dynamic relationship between the joint position and the joint torque during perturbation, and is often represented in terms of stiffness, damping, and inertia...
2016: IEEE Journal of Translational Engineering in Health and Medicine
M V Rasna, K P Zuhail, U V Ramudu, R Chandrasekar, Surajit Dhara
We study the dynamics of electric field driven multiaxis electro-orientation of birefringent microsheets in both the isotropic and nematic phases of a liquid crystal. For a fixed direction of applied field in the isotropic phase, there are two critical fields above which the microsheets show two orientations. In the nematic phase, it shows three rotations in both planar and homeotropic cells. These orientations are observed at varying voltages and wide time scales and are explained based on the competing effect of the electric, elastic, and viscous torques...
September 2016: Physical Review. E
E Eisenriegler, T W Burkhardt
We consider the fluctuation-induced interaction of two thin, rodlike particles, or "needles," immersed in a two-dimensional critical fluid of Ising symmetry right at the critical point. Conformally mapping the plane containing the needles onto a simpler geometry in which the stress tensor is known, we analyze the force and torque between needles of arbitrary length, separation, and orientation. For infinite and semi-infinite needles we utilize the mapping of the plane bounded by the needles onto the half plane, and for two needles of finite length we use the mapping onto an annulus...
September 2016: Physical Review. E
Lorena Maldonado-Camargo, Carlos Rinaldi
We report observations of breakdown of the Stokes-Einstein relation for the rotational diffusivity of polymer-grafted spherical nanoparticles in polymer melts. The rotational diffusivity of magnetic nanoparticles coated with poly(ethylene glycol) dispersed in poly(ethylene glycol) melts was determined through dynamic magnetic susceptibility measurements of the collective rotation of the magnetic nanoparticles due to imposed time-varying magnetic torques. These measurements clearly demonstrate the existence of a critical molecular weight for the melt polymer, below which the Stokes-Einstein relation accurately describes the rotational diffusivity of the polymer-grafted nanoparticles and above which the Stokes-Einstein relation ceases to apply...
November 9, 2016: Nano Letters
Marco Schieppati, Jean Louis Honeine, Manh-Cuong Do, Oscar Crisafulli
OBJECTIVE: The critical action for gait initiation involves lifting of the swing leg while shifting the centre of mass (CoM) of the body over the stance leg. This action is made possible by the initial displacement of the centre of pressure (CoP) in the direction of the swing leg. We hypothesised that the CoP displacement requires a coordinated action of the swing-leg abductor muscles and of the dorsiflexor muscles of the stance leg. MATERIAL/PATIENTS AND METHODS: Nine subjects initiated gait starting from three different initial stance widths (small, medium, wide)...
September 2016: Annals of Physical and Rehabilitation Medicine
Z Yan, J Jin, W J Feng
In this paper, a model of torque dependence of critical current in a Bi2223/Ag composite concentric cylinder is analyzed. Based on the hypothesis of planar section and elastic linear strengthening constitutive theory, the relation between torque and shear strain is firstly obtained. Then a linear weakening relation between critical current density and shear strain are put forward. Finally the effects of the applied torque together with the mechanical properties of superconducting core on the degradation behavior of critical current are calculated and discussed...
2016: SpringerPlus
Vegard Flovik, Ferran Macià, Erik Wahlström
The collective dynamics in populations of magnetic spin torque oscillators (STO) is an intensely studied topic in modern magnetism. Here, we show that arrays of STO coupled via dipolar fields can be modeled using a variant of the Kuramoto model, a well-known mathematical model in non-linear dynamics. By investigating the collective dynamics in arrays of STO we find that the synchronization in such systems is a finite size effect and show that the critical coupling-for a complete synchronized state-scales with the number of oscillators...
2016: Scientific Reports
Jiahao Han, Yuyan Wang, Feng Pan, Cheng Song
Antiferromagnet (AFM) spintronics with reduced electrical current is greatly expected to process information with high integration and low power consumption. In Pt/FeMn and Ta/FeMn hybrids, we observe significant resistance variation (up to 7% of the total resistance) manipulated by 10(5) A/cm(2) dc current. We have excluded the contribution of isotropic structural effects, and confirmed the critical role of the spin Hall injection from Pt (or Ta) to FeMn. This electrical current-manipulated resistance (i...
2016: Scientific Reports
Hossein Rouhani, Milos R Popovic, Michael Same, Ya Qi Li, Kei Masani
Modeling the muscle response to functional electrical stimulation (FES) is an essential step in the design of closed-loop controlled neuroprostheses. This study was aimed at identifying the dynamic response of ankle plantar-flexors to FES during quiet standing. Thirteen healthy subjects stood in a standing frame that locked the knee and hip joints. The ankle plantar-flexors were stimulated bilaterally through surface electrodes and the generated ankle torque was measured. The pulse amplitude was sinusoidally modulated at five different frequencies...
August 17, 2016: Medical Engineering & Physics
V Vanhoorne, L Janssens, J Vercruysse, T De Beer, J P Remon, C Vervaet
HPMC is a popular matrix former to formulate tablets with extended drug release. Tablets with HPMC are preferentially produced by direct compression. However, granulation is often required prior to tableting to overcome poor flowability of the formulation. While continuous twin screw granulation has been extensively evaluated for granulation of immediate release formulations, twin screw granulation of controlled release formulations including the dissolution behavior of the formulations received little attention...
September 25, 2016: International Journal of Pharmaceutics
Marco Laubacher, Efe A Aksöz, Stuart Binder-Macleod, Kenneth J Hunt
Spatially distributed sequential stimulation (SDSS) has demonstrated substantial power output and fatigue benefits compared to single electrode stimulation (SES) in the application of functional electrical stimulation (FES). This asymmetric electrode setup brings new possibilities but also new questions since precise placement of the electrodes is one critical factor for good muscle activation. The aim of this study was to compare the power output, fatigue and activation properties of proximally versus distally placed SDSS electrodes in an isokinetic knee extension task simulating knee movement during recumbent cycling...
June 13, 2016: European Journal of Translational Myology
Woosun Jang, Kisung Kang, Aloysius Soon
Many different forms of mechanical and structural deformations have been employed to alter the electronic structure of various modern two-dimensional (2D) nanomaterials. Given the recent interest in the new class of 2D nanomaterials - phosphorene, here we investigate how the rotational strain-dependent electronic properties of low-dimensional phosphorene may be exploited for technological gain. Here, using first-principles density-functional theory, we investigate the mechanical stability of twisted one-dimensional phosphorene nanoribbons (TPNR) by measuring their critical twist angle (θc) and shear modulus as a function of the applied mechanical torque...
August 4, 2016: Nanoscale
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