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Dynamic stretching

Gregory S Antonarakis, Sandra Fastlicht, Taras Masnyi, Bryan Tompson
Microstomia, an abnormally small oral orifice, is a complication of perioral facial burns. In this case, contraction of the circumoral tissues and hypotonia of the musculature is responsible for this microstomia, which can produce aesthetic and functional impairment with eating, swallowing, communication (speech and facial expressions), compromised dental care and maintenance due to limited oral access, social interactions, and psychological well-being. Conservative management involves providing physical resistance to scar contracture, with opposing horizontal and vertical circumoral forces by means of appliances that aim to stretch the commissures and fibrotic muscles...
March 13, 2017: Journal of Burn Care & Research: Official Publication of the American Burn Association
Andrea R Westervelt, Michael Fernandez, Michael House, Joy Vink, Chia-Ling Nhan-Chang, Ronald Wapner, Kristin M Myers
Preterm birth is the leading cause of childhood mortality, and can lead to health risks in survivors. The mechanical function of the uterus, fetal membranes, and cervix have dynamic roles to protect the fetus during gestation. To understand their mechanical function and relation to preterm birth, we built a 3-dimensional parameterized finite element model of pregnancy. This model is generated by an automated procedure that is informed by maternal ultrasound measurements. A baseline model at 25 weeks of gestation was characterized, and to visualize the impact of cervical structural parameters on tissue stretch we evaluated the model sensitivity to: (1) anterior uterocervical angle, (2) cervical length, (3) posterior cervical offset, and (4) cervical stiffness...
March 17, 2017: Journal of Biomechanical Engineering
Rodolfo Briones, Camilo Aponte-Santamaría, Bert L de Groot
Hydrophobic matching, lipid sorting, and protein oligomerization are key principles by which lipids and proteins organize in biological membranes. The Aquaporin-0 channel (AQP0), solved by electron crystallography (EC) at cryogenic temperatures, is one of the few protein-lipid complexes of which the structure is available in atomic detail. EC and room-temperature molecular dynamics (MD) of dimyristoylglycerophosphocholine (DMPC) annular lipids around AQP0 show similarities, however, crystal-packing and temperature might affect the protein surface or the lipids distribution...
2017: Frontiers in Physiology
Kengo Saito, Qiling Peng, Lin Qiao, Lin Wang, Tatsuya Joutsuka, Tatsuya Ishiyama, Shen Ye, Akihiro Morita
Sum frequency generation (SFG) spectroscopy is widely used to observe molecular orientation at interfaces through a combination of various types of polarization. The present work thoroughly examines the relation between the polarization dependence of SFG signals and the molecular orientation, by comparing SFG measurements and molecular dynamics (MD) simulations of acetonitrile/water solutions. The present SFG experiment and MD simulations yield quite consistent results on the ratios of χ((2)) elements, supporting the reliability of both means...
March 16, 2017: Physical Chemistry Chemical Physics: PCCP
Mani Fathali, Saber Khoei
Time evolution of the fully resolved incompressible homogeneous turbulent shear flow in noninteger Fourier dimensions is numerically investigated. The Fourier dimension of the flow field is extended from the integer value 3 to the noninteger values by projecting the Navier-Stokes equation on the fractal set of the active Fourier modes with dimensions 2.7≤d≤3.0. The results of this study revealed that the dynamics of both large and small scale structures are nontrivially influenced by changing the Fourier dimension d...
February 2017: Physical Review. E
Weixin Qian, Kentaro Doi, Satoyuki Kawano
Electrokinetic phenomena in micro/nanofluidic channels have attracted considerable attention because precise control of molecular transport in liquids is required to optically and electrically capture the behavior of single molecules. However, the detailed mechanisms of polymer transport influenced by electroosmotic flows and electric fields in micro/nanofluidic channels have not yet been elucidated. In this study, a Langevin dynamics simulation was used to investigate the electrokinetic transport of single-stranded DNA (ssDNA) in a cylindrical nanochannel, employing a coarse-grained bead-spring model that quantitatively reproduced the radius of gyration, diffusion coefficient, and electrophoretic mobility of the polymer...
March 14, 2017: Biophysical Journal
Yudai Suzuki, Yuki Nojima, Shoichi Yamaguchi
Unraveling vibrational coupling is the key to consistently interpret vibrational spectra of complex molecular systems. The vibrational spectrum of the water surface heavily suffers from vibrational coupling, which hinders complete understanding of the molecular structure and dynamics of the water surface. Here we apply heterodyne-detected sum frequency generation spectroscopy to the water surface and accomplish the assignment of a weak vibrational band located at the lower energy side of the free OH stretch...
March 15, 2017: Journal of Physical Chemistry Letters
C M Gabbott, Z X Zhou, G X Han, T Sun
At the core of translational challenges in tissue engineering is the mechanistic understanding of the underpinning biological processes and the complex relationships among components at different levels, which is a challenging task due to the limitations of current tissue culture and assessment methodologies. Therefore, we proposed a novel scale-down strategy to deconstruct complex biomatrices into elementary building blocks, which were resembled by thin modular substrate and then evaluated separately in miniaturised bioreactors using various conventional microscopes...
March 15, 2017: Journal of Microscopy
Anastasia Valerievna Keller, Kathlene Marie Rees, Daniella Christina Prince, Johnny R Morehouse, Alice Shum-Siu, David Sk Magnuson
Joint contractures and spasticity are two common secondary complications of a severe spinal cord injury (SCI) that can significantly reduce quality of life and stretching is one of the top strategies for rehabilitation of these complications. We have previously shown that a daily static stretching protocol administered to rats at either acute or chronic time points after a moderate or moderate-severe T10 SCI significantly disrupts their hindlimb locomotor function. The objective of the current study was to examine the effects of dynamic range of motion stretching on the locomotor function of rats with SCI as an alternative to static stretching...
March 13, 2017: Journal of Neurotrauma
Paul Stevenson, Andrei Tokmakoff
Understanding electrostatics of lipid membranes at a molecular level has the potential to offer great insight into the mechanism of voltage-gated processes, but has been challenging to study experimentally. In this study, we characterize the equilibrium electric field fluctuations at the interfacial region of lipid bilayers by using a combination of ultrafast time-resolved infrared spectroscopy, molecular dynamics (MD) simulations and spectral modelling. By monitoring the dynamics of the ester carbonyl stretching vibration in hydrated phosphocholine lipid bilayers, we are able to measure a correlation function for the femtosecond and picosecond fluctuations in the local electric field of the membrane, estimating the standard deviation in these fluctuations as ~10MV/cm...
March 9, 2017: Journal of the American Chemical Society
Alessandro Benedetto, Maria Concetta Morrone
Action and perception are intimately coupled systems; one clear case is saccadic suppression, the reduced visibility around the time of saccades, important in mediating visual stability; another is the oscillatory modulation of visibility synchronized with hand action. To suppress effectively the spurious retinal motion generated by the eye movements, it is crucial that saccadic suppression and saccadic onset be temporally synchronous. However, the mechanisms that determine this temporal synchrony are unknown...
March 7, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Nina Ignatova, Vinícius V Cruz, Rafael C Couto, Emelie Ertan, Andrey Zimin, Freddy F Guimarães, Sergey Polyutov, Hans Ågren, Victor Kimberg, Michael Odelius, Faris Gel'mukhanov
As is well established, the symmetry breaking by isotope substitution in the water molecule results in localisation of the vibrations along one of the two bonds in the ground state. In this study we find that this localisation may be broken in excited electronic states. Contrary to the ground state, the stretching vibrations of HDO are delocalised in the bound core-excited state in spite of the mass difference between hydrogen and deuterium. The reason for this effect can be traced to the narrow "canyon-like" shape of the potential of the state along the symmetric stretching mode, which dominates over the localisation mass-difference effect...
March 7, 2017: Scientific Reports
Tiffany Victor, Natalie Delpratt, Sarah Beth Cseke, Lisa M Miller, Leland James Cseke
Symbiotic associations in the rhizosphere between plants and microorganisms lead to efficient changes in the distribution of nutrients that promote growth and development for each organism involved. Understanding these nutrient fluxes provides insight into the molecular dynamics involved in nutrient transport from one organism to the other. To study such nutrient flow, a new application of Fourier transform infrared imaging (FTIRI) was developed that entailed growing Populus tremulodes seedlings on a thin, nutrient-enriched Phytagel matrix that allows pixel to pixel measurement of the distribution of nutrients - in particular nitrate - in the rhizosphere...
March 6, 2017: Analytical Chemistry
Friedl De Groote, Jessica L Allen, Lena H Ting
Simulating realistic musculoskeletal dynamics is critical to understanding neural control of muscle activity evoked in sensorimotor feedback responses that have inherent neural transmission delays. Thus, the initial mechanical response of muscles to perturbations in the absence of any change in muscle activity determines which corrective neural responses are required to stabilize body posture. Muscle short-range stiffness, a history-dependent property of muscle that causes a rapid and transient rise in muscle force upon stretch, likely affects musculoskeletal dynamics in the initial mechanical response to perturbations...
February 21, 2017: Journal of Biomechanics
G A Shilovsky, T S Putyatina, S N Lysenkov, V V Ashapkin, O S Luchkina, A V Markov, V P Skulachev
Accumulation of various types of lesions in the course of aging increases an organism's vulnerability and results in a monotonous elevation of mortality rate, irrespective of the position of a species on the evolutionary tree. Stroustrup et al. (Nature, 530, 103-107) [1] showed in 2016 that in the nematode Caenorhabditis elegans, longevity-altering factors (e.g. oxidative stress, temperature, or diet) do not change the shape of the survival curve, but either stretch or shrink it along the time axis, which the authors attributed to the existence of an "aging program"...
December 2016: Biochemistry. Biokhimii︠a︡
Martin Loughran, Philip Glasgow, Chris Bleakley, Joseph McVeigh
OBJECTIVES: To determine the effect of three different static-dynamic stretching protocols on sprint and jump performance in Gaelic footballers. DESIGN: Double-blind, controlled, crossover trial. SETTING: Sports Institute research environment. PARTICIPANTS: Seventeen male elite level Gaelic footballers, aged 18-30 years, completed three stretching protocols. MAIN OUTCOME MEASURES: Athletic performance was measured by countermovement jump height and power, and timed 10 m, 20 m, and 40 m sprints...
December 1, 2016: Physical Therapy in Sport
Kevin W Young, Bill P-P Kuo, Shawn M O'Connor, Stojan Radic, Richard L Lieber
Muscle force is dictated by micrometer-scale contractile machines called sarcomeres. Whole-muscle force drops from peak force production to zero with just a few micrometers of sarcomere length change. No current technology is able to capture adequate dynamic sarcomere data in vivo, and thus we lack fundamental data needed to understand human movement and movement disorders. Methods such as diffraction, endoscopy, and optical coherence tomography have been applied to muscle but are prohibitively invasive, sensitive to motion artifact, and/or imprecise...
February 28, 2017: Biophysical Journal
Jie Lu, Yankun Lv, Youxin Ji, Xiaoliang Tang, Zeming Qi, Liangbin Li
We demonstrate the use of a pump-probe setup based on two mid-infrared quantum cascade lasers (QCLs) to investigate the melting and crystallization of materials through resonant absorption. A combination of pump and probe beams fulfills the two-color synchronous detection. Furthermore, narrow linewidth advances the accuracy of measurements and the character of broad tuning range of QCLs enables wide applications in various sample and multiple structures. 1-Eicosene was selected as a simple model system to verify the feasibility of this method...
February 2017: Review of Scientific Instruments
Boris A Kolesov
We present a Raman-spectroscopic study of secondary amides (acetanilide, methacetin, phenacetine, orthorhombic and monoclinic polymorphs of paracetamol) as well as simple amides formanilide and benzanilide. The study was carried out on single crystals and in the temperature range of 5-300K. The series of compounds with the same molecular fragment - acetamide group - can serve as a model system to study the interrelation between this group and the properties of the intermolecular "peptide-type" NH⋯OC hydrogen bonds...
February 24, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
Lili Li, Chuang Feng, Jie Yang
The effect of prestrain on tensile and compressive behaviors of single-layer black phosphorus (SLBP) in both armchair and zigzag directions is investigated by using molecular dynamics simulations. Prestrain is carried out by stretching or compressing SLBP in an orthogonal in-plane direction. The results show that the overall mechanical properties of SLBP, including Young's modulus, tensile strength, compressive strength, and yield strength are enhanced with an increase in compressive prestrain but are reduced with an increased tensile prestrain...
March 1, 2017: Nanoscale
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