9,427 results match your criteria reaction forces

Linear elastic and hyperelastic studies of equine hoof mechanical response at different hydration levels.

J Mech Behav Biomed Mater 2021 Jun 5;121:104622. Epub 2021 Jun 5.

Department of Veterinary Biosciences, The University of Melbourne, Melbourne, VIC, Australia.

Most simulation studies on equine hoof biomechanics employed linear elastic (LE) material models. However, the equine hoof wall's stress-strain relationship is nonlinear and varies with hydration level. Therefore, it is essential to investigate the accuracy of the LE model compared to more advanced material models, such as hyperelastic (HE) or viscoelastic models. Read More

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Effects of additional load at different heights on gait initiation: A statistical parametric mapping of center of pressure and center of mass behavior.

PLoS One 2021 11;16(6):e0242892. Epub 2021 Jun 11.

Physical Education Department, Federal University of São Carlos, São Carlos, Brazil.

The purpose of this study was to investigate the effects of different vertical positions of an asymmetrical load on the anticipatory postural adjustments phase of gait initiation. Sixty-eight college students (32 males, 36 females; age: 23.65 ± 3. Read More

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Electric-Field Control of a Single-Atom Polar Bond.

Phys Rev Lett 2021 May;126(21):216801

Institut für Physik, Technische Universität Ilmenau, D-98693 Ilmenau, Germany.

We expose the polar covalent bond between a single Au atom terminating the apex of an atomic force microscope tip and a C atom of graphene on SiC(0001) to an external electric field. For one field orientation, the Au─C bond is strong enough to sustain the mechanical load of partially detached graphene, while for the opposite orientation, the bond breaks easily. Calculations based on density-functional theory and nonequilibrium Green's function methods support the experimental observations by unveiling bond forces that reflect the polar character of the bond. Read More

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Management of COVID-19 in a Deployed Setting.

Mil Med 2021 Jun 11. Epub 2021 Jun 11.

US Army Institute of Surgical Research, San Antonio, TX 78234, USA.

Introduction: Hamid Karzai International Airport is a NATO military base connected to the international airport in Kabul, Afghanistan. It is one of the larger NATO installations in Afghanistan, and with its location being one of the main hubs for international transit, the base has been at the frontline since the beginning of the COVID-19 pandemic. Hamid Karzai International Airport base commanders and medical staff have been at the forefront, continually developing policies and procedures to mitigate the pandemic in a deployed setting. Read More

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In-Vitro Study of Speed and Alignment Angle in Cochlear Implant Electrode Array Insertions.

IEEE Trans Biomed Eng 2021 Jun 10;PP. Epub 2021 Jun 10.

Objective: The insertion of the electrode array is a critical step in cochlear implantation. Herein we comprehensively investigate the impact of the alignment angle and feed-forward speed on deep insertions in artificial scala tympani models with accurate macro-anatomy and controlled frictional properties.

Methods: Motorized insertions (n=1033) were performed in six scala tympani models with varying speeds and alignment angles. Read More

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Excited-state proton-coupled electron transfer within ion pairs.

Chem Sci 2020 Mar 3;11(13):3460-3473. Epub 2020 Mar 3.

Department of Chemistry, Ångström Laboratories, Uppsala University Box 523 SE75120 Uppsala Sweden

The use of light to drive proton-coupled electron transfer (PCET) reactions has received growing interest, with recent focus on the direct use of excited states in PCET reactions (ES-PCET). Electrostatic ion pairs provide a scaffold to reduce reaction orders and have facilitated many discoveries in electron-transfer chemistry. Their use, however, has not translated to PCET. Read More

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Evaluation of force feedback in walking using joint torques as 'naturalistic' stimuli.

J Neurophysiol 2021 Jun 9. Epub 2021 Jun 9.

Department of Biological Cybernetics, grid.7491.bBielefeld University, Germany.

Control of adaptive walking requires the integration of sensory signals of muscle force and load. We have studied how mechanoreceptors (tibial campaniform sensilla) encode 'naturalistic' stimuli derived from joint torques of stick insects walking on a horizontal substrate. Previous studies showed that forces applied to the legs using the mean torque profiles of a proximal joint were highly effective in eliciting motor activities. Read More

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Using a simple rope-pulley system that mechanically couples the arms, legs, and treadmill reduces the metabolic cost of walking.

J Neuroeng Rehabil 2021 Jun 7;18(1):96. Epub 2021 Jun 7.

Department of Health and Human Performance, Center for Neuromotor and Biomechanics Research, University of Houston, 3875 Holman St., Rm 104 Garrison, Houston, TX, 77204-6015, USA.

Background: Emphasizing the active use of the arms and coordinating them with the stepping motion of the legs may promote walking recovery in patients with impaired lower limb function. Yet, most approaches use seated devices to allow coupled arm and leg movements. To provide an option during treadmill walking, we designed a rope-pulley system that physically links the arms and legs. Read More

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A multi-scale agent-based model for avascular tumour growth.

Biosystems 2021 Jun 9;206:104450. Epub 2021 Jun 9.

Department of Computer Science and Engineering, University of Kalyani, West Bengal 741235, India. Electronic address:

In this paper, we have developed a multi-scale, lattice-free, agent based model of avascular tumour growth in epithelial tissue. The model integrates different events to identify the underlying diversity within intracellular, cellular, and extracellular layer dynamics. The model considers every cell as an agent. Read More

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Two-Channel model for Electron Transfer in a Dye-Catalyst-Dye Supramolecular Complex for Photocatalytic Water Splitting.

ChemSusChem 2021 Jun 7. Epub 2021 Jun 7.

Leiden university, Leiden institute of chemistry, Einsteinweg 55, 2300 RA, Leiden, NETHERLANDS.

To improve the performance of dye-sensitized photoelectrochemical cell (DS-PEC) devices for splitting water, the tailoring of the photocatalytic four-photon water oxidation half-reaction represents a principle challenge of fundamental significance. Here we consider a Ru-based water oxidation catalyst (WOC) covalently bound to two 2,6-diethoxy-1,4,5,8-diimide-naphthalene (NDI) dye functionalities providing comparable driving forces and channels for electron transfer. Constrained ab initio molecular dynamics simulations are performed to investigate the photocatalytic cycle of this two-channel model for photocatalytic water splitting. Read More

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Intramuscular EMG-driven Musculoskeletal Modelling: Towards Implanted Muscle Interfacing in Spinal Cord Injury Patients.

IEEE Trans Biomed Eng 2021 Jun 7;PP. Epub 2021 Jun 7.

Objective: Surface EMG-driven modelling has been proposed as a means to control assistive devices by estimating joint torques. Implanted EMG sensors have several advantages over wearable sensors but provide a more localized information on muscle activity, which may impact torque estimates. Here, we tested and compared the use of surface and intramuscular EMG measurements for the estimation of required assistive joint torques using EMG driven modelling. Read More

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Internal and External Influences on Stability and Ligand Exchange Reactions in Bromido[3-ethyl-4-aryl-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2-imidazol-2-ylidene]gold(I) Complexes.

Inorg Chem 2021 Jun 7. Epub 2021 Jun 7.

Department of Pharmaceutical Chemistry, Institute of Pharmacy, Center for Molecular Biosciences Innsbruck, University of Innsbruck, Innrain 80/82, Innsbruck A-6020, Austria.

The ligand scrambling reaction of gold(I) complexes is a phenomenon occurring primarily in L-Au-X (L = phosphine, -heterocyclic carbene (NHC), and thiol; X = halide and thiol) complexes and has been observed among others for e.g., the bromido[3-ethyl-4-(4-methoxyphenyl)-5-(2-methoxypyridin-5-yl)-1-propyl-1,3-dihydro-2-imidazol-2-ylidene]gold(I) complex (), which underwent ligand rearrangement in aqueous solutions. Read More

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Dose-dependent threshold illumination for non-invasive time-lapse fluorescence imaging of live cells.

Extreme Mech Lett 2021 Jul 3;46. Epub 2021 Mar 3.

Dept. of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign.

Fluorescent microscopy employs monochromatic light for excitation, which can adversely affect the cells being observed. We reported earlier that fibroblasts relax their contractile force in response to green light of typical intensity. Here we show that such effects are independent of extracellular matrix and cell lines. Read More

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Locomotory behaviour of early tetrapods from Blue Beach, Nova Scotia, revealed by novel microanatomical analysis.

R Soc Open Sci 2021 May 26;8(5):210281. Epub 2021 May 26.

McCaig Institute for Bone and Joint Health, University of Calgary, 3330 Hospital Drive NW, Calgary, Alberta, Canada T2N 4N1.

Evidence for terrestriality in early tetrapods is fundamentally contradictory. Fossil trackways attributed to early terrestrial tetrapods long predate the first body fossils from the Late Devonian. However, the Devonian body fossils demonstrate an obligatorily aquatic lifestyle. Read More

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The intimate relationship between structural relaxation and the energy landscape of monatomic liquid metals.

Sci Rep 2021 Jun 3;11(1):11815. Epub 2021 Jun 3.

University of Grenoble Alpes, CNRS, Grenoble INP, SIMaP, 38000, Grenoble, France.

The characteristic property of a liquid, discriminating it from a solid, is its fluidity, which can be expressed by a velocity field. The reaction of the velocity field on forces is enshrined in the transport parameter viscosity. In contrast, a solid reacts to forces elastically through a displacement field, the particles are trapped in their potential minimum. Read More

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A novel evodiamine amino derivative as a PI3K/AKT signaling pathway modulator that induces apoptosis in small cell lung cancer cells.

Eur J Pharmacol 2021 May 31;906:174215. Epub 2021 May 31.

Chongqing Research Center for Pharmaceutical Engineering, Chongqing Medical University, Chongqing 400016, China. Electronic address:

Evodiamine (EVO) was derivatized to a C10-amino derivative (EVA) using a two-step method suitable for industrializing production. This method has advantages such as a short reaction time, high yield, few byproducts and simple purification. The AUC and C values of EVA were 7. Read More

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Preparatory Knee Flexion-Extension Movements Enhance Rapid Sidestepping Performance in Collegiate Basketball Players.

Front Sports Act Living 2021 17;3:670649. Epub 2021 May 17.

College of Sport and Health Science, Ritsumeikan University, Kusatsu, Japan.

Lower-limb weight-bearing load distribution in stationary standing influences the timing of rapid first step initiation of importance for functional movement activities and agility performance in sports. This study investigated the effect of pre-step lower-limb loading and unloading with preparatory knee flexion-extension movements on sidestepping performance in fifteen male collegiate basketball players. Participants performed two-choice (step limb) reaction time sidestepping under two conditions: without preparatory movements before the go cue (no-prep-NP) and with continuous alternating knee extension and flexion movements (prep-P). Read More

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A half marathon shifts the mediolateral force distribution at the tibiofemoral joint.

Eur J Sport Sci 2021 Jun 2:1-23. Epub 2021 Jun 2.

Department of Biomedical Engineering, Faculty of Engineering, The Hong Kong Polytechnic University, Hong Kong SAR, China.

Runners' gait patterns vary during a half marathon and influence the knee joint mechanics. Joint contact force is a better estimate of the net joint loadings than external joint moments and closely correlates to injury risks. This study explored the changes of lower limb joint kinematics, muscle activities, and knee joint loading in runners across the running mileages of a half marathon. Read More

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Running Biomechanics of Adolescents with Autism Spectrum Disoder.

J Biomech Eng 2021 Jun 2. Epub 2021 Jun 2.

Department of Human Movement Sciences, Old Dominion University.

Research examining gait biomechanics of persons with autism spectrum disorder (ASD) has grown significantly in recent years and has demonstrated that persons with ASD walk at slower self-selected speeds and with shorter strides, wider step widths, and reduced lower extremity range of motion and moments compared to neurotypical controls. In contrast to walking, running has yet to be examined in persons with ASD. The purpose of this study was to examine lower extremity running biomechanics in adolescents (13-18-year-olds) with ASD and matched (age, sex, and body mass index) neurotypical controls. Read More

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Validity of New Technologies That Measure Bone-Related Dietary and Physical Activity Risk Factors in Adolescents and Young Adults: A Scoping Review.

Int J Environ Res Public Health 2021 May 26;18(11). Epub 2021 May 26.

Charles Perkins Centre, Nutrition and Dietetics Group, School of Life and Environmental Sciences, The University of Sydney, Sydney, NSW 2006, Australia.

New technologies may improve the validity of dietary and physical activity assessment and thereby associated findings for lifestyle-related bone health research. This scoping review mapped the evidence for the validity of new technologies that measure bone-related dietary and physical activity risk factors in adolescents and young adults. A systematic literature search was conducted using seven electronic databases for peer-reviewed studies published from January 2008 to 2021. Read More

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Heating and Compression at Elevated Temperature of Thin-Walled Titanium Channel Section Columns.

Materials (Basel) 2021 May 29;14(11). Epub 2021 May 29.

Department of Strength of Materials, Faculty of Mechanical Engineering, Lodz University of Technology, Stefanowskiego 1/15, 90-924 Lodz, Poland.

The paper deals with numerical and experimental investigations of the channel section column subjected to heating and compression at elevated temperature. The analyzed columns were made of titanium alloy (Grade 2) and simply supported on both ends. The research procedure involved initial compression of the column (i), heating the preloaded column (ii) and compression of the column at elevated temperature to failure (iii). Read More

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Fragment-Based Ab Initio Molecular Dynamics Simulation for Combustion.

Molecules 2021 May 23;26(11). Epub 2021 May 23.

School of Chemistry and Molecular Engineering, Shanghai Engineering Research Center of Molecular Therapeutics & New Drug Development, East China Normal University, Shanghai 200062, China.

We develop a fragment-based ab initio molecular dynamics (FB-AIMD) method for efficient dynamics simulation of the combustion process. In this method, the intermolecular interactions are treated by a fragment-based many-body expansion in which three- or higher body interactions are neglected, while two-body interactions are computed if the distance between the two fragments is smaller than a cutoff value. The accuracy of the method was verified by comparing FB-AIMD calculated energies and atomic forces of several different systems with those obtained by standard full system quantum calculations. Read More

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Analysis of Contact Deformations in Support Systems Using Roller Prisms.

Materials (Basel) 2021 May 18;14(10). Epub 2021 May 18.

Faculty of Mechanical Engineering and Mechatronics, West Pomeranian University of Technology, 19 Piastów Ave., 70-310 Szczecin, Poland.

This article presents the results of finite element analyses of the influence of reaction forces on stresses and strains at the contact points of the rollers of prism supports with cylindrical surfaces of the main journals of large-sized crankshafts. The analyses of strains and stresses, as well as the depth of their occurrences, in the case of the shaft journal and support rollers were carried out using Hertz contact theory and the finite element method. These calculation results proved to be highly consistent. Read More

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Solvent-Induced Formation of Novel Ni(II) Complexes Derived from Bis-Thiosemicarbazone Ligand: An Insight from Experimental and Theoretical Investigations.

Int J Mol Sci 2021 May 19;22(10). Epub 2021 May 19.

Institute of Chemistry, University of Tyumen, Volodarskogo Str. 6, 625003 Tyumen, Russia.

In this work, we report solvent-induced complexation properties of a new NS tetradentate bis-thiosemicarbazone ligand (), prepared by the condensation of 4-phenylthiosemicarbazide with bis-aldehyde, namely 2,2'-(ethane-1,2-diylbis(oxy)dibenzaldehyde, towards nickel(II). Using ethanol as a reaction medium allowed the isolation of a discrete mononuclear homoleptic complex (), for which its crystal structure contains three independent molecules, namely , and , in the asymmetric unit. The doubly deprotonated ligand in the structure of is coordinated in a cis-manner through the azomethine nitrogen atoms and the thiocarbonyl sulfur atoms. Read More

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Structural Response Prediction of Thin-Walled Additively Manufactured Parts Considering Orthotropy, Thickness Dependency and Scatter.

Materials (Basel) 2021 May 10;14(9). Epub 2021 May 10.

Institute of Structural Lightweight Design, Johannes Kepler University Linz, 4040 Linz, Austria.

Besides the design freedom offered by additive manufacturing, another asset lies within its potential to accelerate product development processes by rapid fabrication of functional prototypes. The premise to fully exploit this benefit for lightweight design is the accurate structural response prediction prior to part production. However, the peculiar material behavior, characterized by anisotropy, thickness dependency and scatter, still constitutes a major challenge. Read More

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Utilization of Inertial Measurement Units for Determining the Sequential Chain of Baseball Strike Posture.

Sensors (Basel) 2021 May 10;21(9). Epub 2021 May 10.

Department of Physical Therapy, University of Nevada, Las Vegas, Las Vegas, NV 89154, USA.

The purpose of this study was to employ inertial measurement units (IMU) with an eye-tracking device to investigate different swing strategies between two levels of batters. The participants were 20 healthy males aged 20 to 30 years old, with ten professional and ten amateur batters. Eye gaze position, head, shoulder, trunk, and pelvis angular velocity, and ground reaction forces were recorded. Read More

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Ultrasound-Assisted Synthesis, Antioxidant Activity and Computational Study of 1,3,4-Oxadiazol-2-amines.

Acta Chim Slov 2021 Mar;68(1):109-117

Development of synthetic procedures for the preparation of 1,3,4-oxadiazole derivatives has always been in the interest of researchers as a result of their widespread biological activities. In this study, an ultrasound-assisted procedure was proposed for the synthesis of 1,3,4-oxadiazol-2-amines form the reaction of hydrazides and cyanogen bromide. They were efficiently produced in 81-93% yields in the presence of ethanol and potassium bicarbonate as the reaction media and the base, respectively. Read More

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Ground Reaction Forces and Temporal Characteristics Define Cutting Performance.

Int J Exerc Sci 2021 1;14(1):211-221. Epub 2021 Apr 1.

School of Nursing and Human Physiology, Human Physiology Department, Gonzaga University, Spokane, WA, UNITED STATES.

Moderate angle cutting maneuvers (between 45º and 90º) are common and essential performance skills for success in multidirectional sports. Research addresses the injury risks of cutting but few studies have attempted to quantify the performance of the cut itself.

Purpose: To identify any anthropometric, kinematic, and/or kinetic markers of a high-performance cut so they may be taught and lead to more effective training. Read More

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Exploring the binding mechanism of β-resorcylic acid with calf thymus DNA: Insights from multi-spectroscopic, thermodynamic and bioinformatics approaches.

Spectrochim Acta A Mol Biomol Spectrosc 2021 Nov 12;260:119952. Epub 2021 May 12.

Department of Biochemistry, Faculty of Life Sciences, A.M.U, Aligarh, U.P. 202002, India. Electronic address:

β-resorcylic acid (BR) is a phytochemical which is widely used in the food industry as a flavouring agent and preservative. It has also been found to exhibit antibacterial action against several types of food-borne bacteria. DNA is the main molecular target for many small molecules of therapeutic importance. Read More

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November 2021

Overground Walking Biomechanics of Dissatisfied Persons With Total Knee Replacements.

J Appl Biomech 2021 May 29:1-8. Epub 2021 May 29.

Tennessee Orthopaedic Clinics.

Patient dissatisfaction following total knee replacement (TKR) procedures is likely influenced by both subjective and objective aspects. Increased pain and reduced performance on clinical tests have been shown in persons who are dissatisfied with the outcome of their surgery. However, it is unknown how overground walking kinematics and kinetics might differ in the dissatisfied versus satisfied patients following TKR surgery. Read More

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