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Dynamic stretching

Bowen Li, Ying Yu, Xiaoming Wei, Yiqing Xu, Kevin K Tsia, Kenneth K Y Wong
Fiber-stretcher based phase-lock loop (PLL) is a mature technique in fiber mode-locked lasers for repetition-rate stabilization. However, undesired side effects may be induced if not properly handled, which is easily overlooked owing to the lack of single-shot spectral analyzers. Thanks to the ultrafast spectral analyzing capability of optical time-stretch, an intriguing spectral dynamics is observed in a repetition-rate-stabilized nonlinear polarization rotation (NPR) mode-locked laser. Under the dynamic state, the optical spectra of pulses undergo dramatic evolution in every round trip while the pulse energy is relatively constant...
April 17, 2017: Optics Express
Eun-Hye Ko, Hyo-Joong Kim, Sang-Mok Lee, Tae-Woong Kim, Han-Ki Kim
We report on semi-transparent stretchable Ag films coated on a wavy-patterned polydimethylsiloxane (PDMS) substrate for use as stretchable electrodes for stretchable and transparent electronics. To improve the mechanical stretchability of the Ag films, we optimized the wavy-pattern of the PDMS substrate as a function of UV-ozone treatment time and pre-strain of the PDMS substrate. In addition, we investigated the effect of the Ag thickness on the mechanical stretchability of the Ag electrode formed on the wavy-patterned PDMS substrate...
April 24, 2017: Scientific Reports
Rajib Biswas, William Carpenter, Joseph A Fournier, Gregory A Voth, Andrei Tokmakoff
The local environmental sensitivity of infrared (IR) spectroscopy to a hydrogen-bonding structure makes it a powerful tool for investigating the structure and dynamics of excess protons in water. Although of significant interest, the line broadening that results from the ultrafast evolution of different solvated proton-water structures makes the assignment of liquid-phase IR spectra a challenging task. In this work, we apply a normal mode analysis using density functional theory of thousands of proton-water clusters taken from reactive molecular dynamics trajectories of the latest generation multistate empirical valence bond proton model (MS-EVB 3...
April 21, 2017: Journal of Chemical Physics
Guang-Hao Shao, Shao-Cheng Yan, Wei Luo, Guo-Wei Lu, Yan-Qing Lu
We propose and numerically demonstrate a conversion and multicasting scheme of orbital angular momentum (OAM) states by using N-core supermode fiber (NCSF), where the topological charges of converted OAM states mainly depend on the injected OAM state and the number of fiber cores. The conversion efficiency (CE) of the converted OAM states could be optimized by properly designing the fiber structure. Take N = 6 as an example, ~37% CE could be achieved at telecom bands. Moreover, even for a fabricated NCSF, the CE could be dynamically changed by stretching the fiber or by adjusting the refractive index of the fiber cores through external control of the environmental conditions...
April 21, 2017: Scientific Reports
Christopher A Rumble, Caleb Uitvlugt, Brian Conway, Mark Maroncelli
Herein are reported temperature-dependent measurements and molecular dynamics simulations designed to investigate the effects of molecular size, shape, and electrostatics on rotational dynamics in ionic liquids. Experiments were performed in the representative ionic liquid 1-butyl-3-methylimadazolium tetrafluoroborate ([Im41][BF4]) and simulations in the generic ionic liquid model ILM2 as well as a more detailed representation of [Im41][BF4]. 2H longitudinal spin relaxation times were measured for deuterated versions of 1,4-dimethylbenzene, 1-cyano-4-methylbenzene, and 1,4-dimethylpyridinium between 296-337 K...
April 21, 2017: Journal of Physical Chemistry. B
Marc-Antoine Sani, Catharina Saenger, Davor Juretic, Frances Separovic
With the rise in antibiotic resistance, antimicrobial peptides (AMPs) show promise for therapeutic development but higher specificity is required. PGLa-H is a naturally occurring decapeptide, reported to have moderate antibacterial activity and low hemolytic activity, with its sequence being identical to the C-terminal fragment of highly selective AMP, PGLa. DiPGLa-H, a sequential tandem repeat of PGLa-H, as well as Kiadin, an analogue with a Val to Gly substitution at position 15, display improved in vitro bactericidal activity against both Gram-negative and Gram-positive pathogens, with generally low toxicity for human cells...
April 20, 2017: Journal of Physical Chemistry. B
Toshiyuki Takamuku, Yasuhito Higuma, Masaru Matsugami, Takahiro To, Tatsuya Umecky
The solvation structure of 1,3-butanediol (1,3-BD) in aqueous binary solvents of acetonitrile (AN), 1,4-dioxane (DIO), and dimethyl sulfoxide (DMSO) at various mole fractions of organic solvent xOS has been clarified by means of infrared (IR) and 1H and 13C NMR. The change in the wavenumber of O-H stretching vibration of 1,3-BD in the three systems suggested that water molecules which are initially hydrogen-bonded with the 1,3-BD hydroxyl groups in the water solvent (xOS = 0) are more significantly replaced by organic solvent molecules in the order of DMSO > DIO > AN...
April 20, 2017: Journal of Physical Chemistry. B
Najeh Rekik
Theoretical IR spectral density of the high-frequency stretching mode of hydrogen bond (H-bond) systems is reported using a three-dimensional approach. The model, studied within the framework of linear response theory, involves the mechanical anharmonicity of the high-frequency stretching mode by contemplating its potential as an asymmetric double well potential, the mechanical anharmonicity of the H-bond Bridge by contemplating its potential as a Morse potential, Fermi resonances which occur between the high frequency stretching mode and the overtones of the bending modes, the electrical anharmonicity translated by the non-linearity to second order in the electric dipole moment function of the fast mode, the second order modulation of the angular frequency and the equilibrium position of the fast mode on the slow mode coordinate, and direct and indirect relaxation mechanism...
April 18, 2017: Journal of Physical Chemistry. A
Makoto Ashino, Roland Wiesendanger
Bending at the nanometre scale can substantially modify the mechanical, chemical and electronic properties of graphene membranes. The subsequent response of chemical bonds leads to deviations from plate idealisation in continuum mechanics. However, those phenomena have thus far been investigated exclusively by measuring the electronic properties of graphene deformed by compressing and stretching with local-probe techniques. Here, we report that the interatomic-attractive forces applied on the convexly-curved graphene by the probe tip give rise to a pin-point breaking of the plate idealisation in the continuum mechanics, facilitating atomically-localised enhancements in its chemical reactivity and mechanical strength...
April 18, 2017: Scientific Reports
A M S Macêdo, Iván R Roa González, D S P Salazar, G L Vasconcelos
A unified approach is proposed to describe the statistics of the short-time dynamics of multiscale complex systems. The probability density function of the relevant time series (signal) is represented as a statistical superposition of a large time-scale distribution weighted by the distribution of certain internal variables that characterize the slowly changing background. The dynamics of the background is formulated as a hierarchical stochastic model whose form is derived from simple physical constraints, which in turn restrict the dynamics to only two possible classes...
March 2017: Physical Review. E
Nikhil Sindhwani, Christian Bamberg, Nele Famaey, Geertje Callewaert, Joachim W Dudenhausen, Ulf Teichgräber, Jan Deprest
OBJECTIVE: Vaginal childbirth is believed to be a significant risk factor for the development of pelvic floor dysfunction later in life. Previous studies have explored the use of medical imaging and simulations of childbirth to determine the stretch in the levator ani muscle. Bamberg et al, 2012, have recorded MR images of a live childbirth of a 24 year old woman giving birth vaginally for the second time, using a 1.0 Tesla open high-field scanner. Our objective was to determine the stretch ratios in the levator muscle using these MR images of live childbirth...
April 12, 2017: American Journal of Obstetrics and Gynecology
Hwi S Jang, Daeho Kim, Jihong Park
BACKGOUND: Since different types of stretching exercises may alter athletic performance, we compared the effects of three types of stretching exercises on badminton jump smash. METHODS: Sixteen male collegiate badminton players performed one of three different stretching exercises in a counterbalanced order on different days. Static stretching had seven typical stretches, while dynamic stretching involved nine dynamic movements, and resistance dynamic stretching was performed with weighted vests and dumbbells...
April 13, 2017: Journal of Sports Medicine and Physical Fitness
E Broclawik, K Góra-Marek, M Radoń, T Bučko, A Stępniewski
This work is focused on the donor properties of cobalt-exchanged cationic sites in zeolites. It is based on cluster and periodic density functional theory modeling for relevant {[Co(II)(NH3)n]-NO} adducts, where Co(II) means a cobalt cation embedded either in a periodic model of chabasite (CHA) zeolite or in model clusters. NO stretching frequencies were derived from MD trajectories and compared to harmonic values from cluster calculations. By relating calculated NO frequencies to experimental FTIR spectra, it was shown that the forms of {Co(II)-NO} adducts comprising three or four ammonia co-ligands dominate the spectrum taken in ammonia-saturation conditions while forms with two NH3 ligands prevail under intermediate ammonia saturation...
May 2017: Journal of Molecular Modeling
Jaroslav Braniš, Csilla Pataki, Marina Spörrer, Richard C Gerum, Astrid Mainka, Vladimir Cermak, Wolfgang H Goldmann, Ben Fabry, Jan Brabek, Daniel Rosel
CAS is a docking protein, which was shown to act as a mechanosensor in focal adhesions. The unique assembly of structural domains in CAS is important for its function as a mechanosensor. The tension within focal adhesions is transmitted to a stretchable substrate domain of CAS by focal adhesion-targeting of SH3 and CCH domain of CAS, which anchor the CAS protein in focal adhesions. Mechanistic models of the stretching biosensor propose equal roles for both anchoring domains. Using deletion mutants and domain replacements, we have analyzed the relative importance of the focal adhesion anchoring domains on CAS localization and dynamics in focal adhesions as well as on CAS-mediated mechanotransduction...
April 13, 2017: Scientific Reports
Dipen Rajgor, Maria Fiuza, Gabrielle T Parkinson, Jonathan G Hanley
miRNAs are important regulators of localized mRNA translation in neuronal dendrites. The presence of RNA-induced silencing complex (RISC) proteins in these compartments and the dynamic miRNA expression changes that occur in response to neuronal stimulation highlights their importance in synaptic plasticity. Previously we demonstrated a novel interaction between the major RISC component Argounaute-2 (Ago2) and the BAR-domain protein PICK1. PICK1 recruits Ago2 to recycling endosomes in dendrites, where it inhibits miRNA-mediated translational repression...
April 12, 2017: Journal of Biological Chemistry
YoungAh Kwon, Junho Lee, Sungnam Park
Cation-specific ion pairing dynamics between M(+) (M = Ag or Cu) and SCN(-) in N,N-dimethylthioformamide (DMTF) are studied by probing the nitrile (CN) stretching vibration. The SCN(-) ion, which is an ambidentate ligand, readily associates with cations to form two different types of contact ion pairs (CIPs) (i.e., M-SCN or M-NCS) and its CN stretching frequency is significantly blue-shifted so that free SCN(-) and CIPs can be well-distinguished in the FTIR spectra. Interestingly, Ag(+) ions prefer the formation of Ag-SCN in DMTF (Ag(+) + SCN(-) ⇋ Ag-SCN) but Cu(+) ions form Cu-NCS (Cu(+) + SCN(-) ⇋ Cu-NCS)...
April 12, 2017: Physical Chemistry Chemical Physics: PCCP
Steven M Yellon
Major clinical challenges for obstetricians and neonatologists result from early cervix remodeling and preterm birth. Complications related to cervix remodeling or delivery account for significant morbidity in newborns and peripartum mothers. Understanding morphology and structure of the cervix in pregnant women is limited mostly to the period soon before and after birth. However, evidence in rodent models supports a working hypothesis that a convergence of factors promotes a physiological inflammatory process that degrades the extracellular collagen matrix and enhances biomechanical distensibility of the cervix well before the uterus develops the contractile capabilities for labor...
January 1, 2017: Biology of Reproduction
Mohamed Frikha, Mohammad S Derbel, Nesrine Chaâri, Adnene Gharbi, Karim Chamari
The aim of the study was to compare the effect of stretching procedures on global coordination and accuracy in instep soccer kicks achieved in different stress conditions. Twenty male young soccer players completed the global coordination test (GC), the instep kicking accuracy test in free (FKA) and in time-pressure (TPKA) conditions, either after static (SS), dynamic (DS), ballistic (BS) or no-stretching (CTR) protocols, on nonconsecutive days and in a randomized order. After performing a 5min standardized intensity jogging (70% of MAV), followed by stretching exercises for 10min, each participant completed, successively, the GC, FKA and TPKA tests...
April 7, 2017: Human Movement Science
Shailesh Ganpule, Nitin P Daphalapurkar, Kaliat T Ramesh, Andrew K Knutsen, Dzung L Pham, Philip V Bayly, Jerry L Prince
Diffuse axonal injury (DAI) is a debilitating consequence of traumatic brain injury (TBI) attributed to abnormal stretching of axons caused by blunt head trauma or acceleration of the head. We developed an anatomically accurate, subject-specific, three-dimensional (3D) computational model of the human brain, and used it to study the dynamic deformations in the substructures of the brain when the head is subjected to rotational accelerations. The computational head models use anatomy and morphology of the white matter fibers obtained using MRI...
April 10, 2017: Journal of Neurotrauma
Shivaprakash N Ramakrishna, Marco Cirelli, Mohammad Divandari, Edmondo Maria Benetti
The nanotribological properties of hydrophilic polymer brushes are conveniently analyzed by lateral force microscopy (LFM). However, the measurement of friction for highly swollen and relatively thick polymer brushes can be strongly affected by the tendency of the compliant brush to be laterally deformed by the shearing probe. This phenomenon induces a "tilting" in the recorded friction loops, which is generated by the lateral bending and stretching of the grafts. In this study we highlight how the brush lateral deformation mainly affects the friction measurements of swollen PNIPAM brushes (below LCST) when relatively short scanning distances are applied...
April 10, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
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