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Dynamic stretching

David Mark Wilkins, David E Manolopoulos, Silvio Pipolo, Damien Laage, James T Hynes
We combine classical and ring polymer molecular dynamics simulations with the molecular jump model to provide a molecular description of the nuclear quantum effects (NQEs) on water reorientation and hydrogen-bond dynamics in liquid H2O and D2O. We show that while the net NQEs is negligible in D2O, it leads to a ∼13% acceleration in H2O dynamics compared to a classical description. Large angular jumps exchanging hydrogen-bond partners are the dominant reorientation pathway (just as in a classical description); the faster reorientation dynamics arise from the increased jump rate constant...
May 22, 2017: Journal of Physical Chemistry Letters
Tsukasa Takanashi, Kosuke Nakamura, Edwin Kukk, Koji Motomura, Hironobu Fukuzawa, Kiyonobu Nagaya, Shin-Ichi Wada, Yoshiaki Kumagai, Denys Iablonskyi, Yuta Ito, Yuta Sakakibara, Daehyun You, Toshiyuki Nishiyama, Kazuki Asa, Yuhiro Sato, Takayuki Umemoto, Kango Kariyazono, Kohei Ochiai, Manabu Kanno, Kaoru Yamazaki, Kuno Kooser, Christophe Nicolas, Catalin Miron, Theodor Asavei, Liviu Neagu, Markus Schöffler, Gregor Kastirke, Xiao-Jing Liu, Artem Rudenko, Shigeki Owada, Tetsuo Katayama, Tadashi Togashi, Kensuke Tono, Makina Yabashi, Hirohiko Kono, Kiyoshi Ueda
Coulomb explosion of diiodomethane CH2I2 molecules irradiated by ultrashort and intense X-ray pulses from SACLA, the Japanese X-ray free electron laser facility, was investigated by multi-ion coincidence measurements and self-consistent charge density-functional-based tight-binding (SCC-DFTB) simulations. The diiodomethane molecule, containing two heavy-atom X-ray absorbing sites, exhibits a rather different charge generation and nuclear motion dynamics compared to iodomethane CH3I with only a single heavy atom, as studied earlier...
May 22, 2017: Physical Chemistry Chemical Physics: PCCP
Akankshya Shradhanjali, Brandon D Riehl, Jeong Soon Lee, Ligyeom Ha, Jung Yul Lim
The cardiac milieu is mechanically active with spontaneous contraction beginning from early development and persistent through maturation and homeostasis, suggesting that mechanical loading may provide biomimetic myocardial developmental signal. In this study, we tested the role of cyclic mechanical stretch loading in the cardiomyogenesis of pluripotent murine embryonic (P19) stem cells. A Flexcell tension system was utilized to apply equiaxial stretch (12% strain, 1.25 Hz frequency) to P19 cell-derived embryoid bodies (EBs)...
May 17, 2017: Biochemical and Biophysical Research Communications
Michael D Schuder, Fang Wang, Chih-Hsuan Chang, David J Nesbitt
The sub-Doppler CH-symmetric stretch (ν3) infrared absorption spectrum of a hydroxymethyl (CH2OH) radical is observed and analyzed with the radical formed in a slit-jet supersonic discharge expansion (Trot = 18 K) via Cl atom mediated H atom abstraction from methanol. The high sensitivity of the spectrometer and reduced spectral congestion associated with the cooled expansion enable first infrared spectroscopic observation of hydroxymethyl transitions from both ± symmetry tunneling states resulting from large amplitude COH torsional motion...
May 21, 2017: Journal of Chemical Physics
D M Medeiros, C S Lima
The aim of the current study was to investigate the influence of chronic stretching on muscle performance (MP) by a systematic review. The search strategy included MEDLINE, PEDro, Cochrane CENTRAL, LILACS, and manual search from inception to June 2016. Randomized and controlled clinical trials, non-randomized, and single group studies that have analyzed the influence of flexibility training (FT) (using any stretching technique) on MP were included. Differently, studies with special populations (children, elderly, and people with any dysfunction/disease), and articles that have used FT protocols shorter than three weeks or 12 sessions were excluded...
May 17, 2017: Human Movement Science
Yuhao Qiang, Jia Liu, E Du
Erythrocytes must undergo severe deformation to pass through narrow capillaries and submicronic splenic slits for several hundred thousand times in their normal lifespan. Studies of erythrocyte biomechanics have been mainly focused on cell deformability and rheology measured from a single application of stress and mostly under a static or quasi-static state using classical biomechanical techniques, such as optical tweezers and micropipette aspiration. Dynamic behavior of erythrocytes in response to cyclic stresses that contributes to the membrane failure in blood circulation is not fully understood...
May 16, 2017: Acta Biomaterialia
Jan Philip Kraack, Angelo Frei, Roger Alberto, Peter Hamm
We investigate the ultrafast vibrational dynamics of monolayers from adsorbed rhenium-carbonyl CO2-reduction catalysts on a semiconductor surface (indium-tin-oxide (ITO)) with ultrafast two-dimensional attenuated total reflection infrared (2D ATR IR) spectroscopy. The complexes are partially equipped with isotope-labeled ((13)C) carbonyl ligands to generate two spectroscopically distinguishable forms of the molecules. Ultrafast vibrational energy transfer between the molecules is observed via the temporal evolution of cross-peaks between their symmetric carbonyl stretching vibrations...
May 22, 2017: Journal of Physical Chemistry Letters
Carlos R Baiz, Kwang-Im Oh, Kavya Rajesh, John F Stanton
Dimethyl sulfoxide (DMSO) disrupts the hydrogen-bond networks in water. DMSO's widespread uses as a cosolvent, along with its unusual attributes, have inspired numerous studies. In this study, infrared absorption spectroscopy of the S=O stretch combined with molecular dynamics and quantum chemistry models were used to directly quantify DMSO/water hydrogen bond populations in binary mixtures. Singly H-bonded species are dominant at 10 mol%, due to strong DMSO-water interactions. We found an unexpected increase in non-hydrogen-bonded DMSO near the eutectic point (~35 mol%) which also correlates with several abnormalities in the solution's bulk properties...
May 18, 2017: Angewandte Chemie
Xudong Zhang, William Wang, Fang Li, Ioana Voiculescu
This paper presents the fabrication and testing of a novel stretchable electric cell-substrate impedance sensing (ECIS) lab on a chip device. This is the first time that ECIS electrodes were fabricated on a stretchable polydimethylsiloxane (PDMS) substrate and ECIS measurements were performed on mammalian cells exposed to cyclic strain. The stretchable ECIS biosensors simulate in vitro the dynamic environment of organisms, such as pulsation, bending and stretching, which enables investigations on cell behavior that undergoes mechanical stimuli in biological tissue...
May 17, 2017: Lab on a Chip
Fang Niu, Rainer Schulz, Arcesio Castañeda Medina, Rochus Schmid, Andreas Erbe
The electrode potential dependence of the hydration layer on an n-Ge(100) surface was studied by a combination of in situ and operando electrochemical attenuated total reflection infrared (ATR-IR) spectroscopy and real space density functional theory (DFT) calculations. Constant-potential DFT calculations were coupled to a modified generalised Poisson-Boltzmann ion distribution model and applied within an ab initio molecular dynamics (AIMD) scheme. As a result, potential-dependent vibrational spectra of surface species and surface water were obtained, both experimentally and by simulations...
May 17, 2017: Physical Chemistry Chemical Physics: PCCP
Sergy Yu Grebenshchikov
A combined ab initio and quantum dynamical study characterizes a family of bent neutral carbon dioxide molecules in terms of their vibrational levels, electric dipole moment surfaces, and infrared spectra in the gas phase. The considered isomers include the dioxiranylidene form of CO2 with the equilibrium valence angle of 72(o), belonging to the ground electronic state, and four open structures with the valence angles of 118(o)/119(o) (they belong to the singlet and triplet electronic states 2(1)A' and 1(3)A', respectively) and 127(o)/128(o) (states 1(1)A" and 1(3)A", respectively)...
May 17, 2017: Journal of Physical Chemistry. A
Paul Brocklehurst, Haibo Ni, Henggui Zhang, Jianqiao Ye
We investigate the effect of mechano-electrical feedback and atrial fibrillation induced electrical remodelling (AFER) of cellular ion channel properties on the dynamics of spiral waves in a discrete 2D model of human atrial tissue. The tissue electro-mechanics are modelled using the discrete element method (DEM). Millions of bonded DEM particles form a network of coupled atrial cells representing 2D cardiac tissue, allowing simulations of the dynamic behaviour of electrical excitation waves and mechanical contraction in the tissue...
2017: PloS One
Ana Maria Cunha, Evgeniia Salamatova, Robbert Bloem, Steven Joop Roeters, Sander Woutersen, Maxim S Pshenichnikov, Thomas L C Jansen
Intrinsically disordered proteins play an important role in biology, and unraveling their labile structure presents a vital challenge. However, the dynamical structure of such proteins thwarts their study by standard techniques such as x-ray diffraction and NMR spectroscopy. Here, we use a neat liquid composed of N-methylacetamide molecules as a model system to elucidate dynamical and structural properties similar to the those one can expect to see in intrinsically disordered peptide systems. To examine the structural dynamics in the neat liquid, we combine molecular dynamics, response-function based spectral simulations, and two-dimensional polarization-resolved infrared spectroscopy in the amide I (CO stretch) region...
May 16, 2017: Journal of Physical Chemistry Letters
Mohsin Abbas, Muhammad Salman Bashir, Rabiya Noor
Different therapies are available for correcting the tightness of hamstring muscles. Objective of this study was to compare the effectiveness of Dynamic Soft Tissue Mobilization DSTM technique and Passive Stretching PS to improve the flexibility of tight hamstrings in cricket players. A total of 120 cricket players having tightness of hamstrings were enrolled and randomized into two groups A and B using lottery method. Group-A was treated with DSTM and group-B with PS to improve the flexibility of hamstrings...
May 2017: JPMA. the Journal of the Pakistan Medical Association
Martijn van Hagen, Diewertje G E Piebes, Wim C de Leeuw, Ilona M Vuist, Willeke M C van Roon-Mom, Perry D Moerland, Pernette J Verschure
BACKGROUND: Huntington's disease (HD) is a fatal neurodegenerative disorder caused by a CAG expansion in the Huntingtin (HTT) gene. Proteolytic cleavage of mutant huntingtin (Htt) protein with an expanded polyglutamine (polyQ) stretch results in production of Htt fragments that aggregate and induce impaired ubiquitin proteasome, mitochondrial functioning and transcriptional dysregulation. To understand the time-resolved relationship between aggregate formation and transcriptional changes at early disease stages, we performed temporal transcriptome profiling and quantification of aggregate formation in living cells in an inducible HD cell model...
May 12, 2017: BMC Genomics
Vishnu Muthuraj Kumarasamy, Daekyu Sun
Dominant-activating mutations in the RET (rearranged during transfection) proto-oncogene, which encodes a receptor tyrosine kinase, is often associated with the development of medullary thyroid carcinoma (MTC). The proximal promoter region of the RET gene consists of a guanine-rich sequence containing five runs of three consecutive guanine residues that serve as the binding site for transcriptional factors. As we have recently shown, this stretch of nucleotides in the promoter region is highly dynamic in nature and tend to form non-B DNA secondary structures called G-quadruplexes, which suppress the transcription of the RET gene...
May 11, 2017: International Journal of Oncology
Thach V Can, Ralph T Weber, Joseph J Walish, Timothy M Swager, Robert G Griffin
The efficiency of continuous wave dynamic nuclear polarization (DNP) experiments decreases at the high magnetic fields used in contemporary high-resolution NMR applications. To recover the expected signal enhancements from DNP, we explored time domain experiments such as NOVEL which matches the electron Rabi frequency to the nuclear Larmor frequency to mediate polarization transfer. However, satisfying this matching condition at high frequencies is technically demanding. As an alternative we report here frequency-swept integrated solid effect (FS-ISE) experiments that allow low power sweeps of the exciting microwave frequencies to constructively integrate the negative and positive polarizations of the solid effect, thereby producing a polarization efficiency comparable to (±10 % difference) NOVEL...
May 12, 2017: Angewandte Chemie
Zhaofeng Ye, Patrick G Needham, Samuel K Estabrooks, Susan K Whitaker, Brandon L Garcia, Saurav Misra, Jeffrey L Brodsky, Carlos J Camacho
C-terminus of Hsc/p70-Interacting Protein (CHIP) is a homodimeric E3 ubiquitin ligase. Each CHIP monomer consists of a tetratricopeptide-repeat (TPR), helix-turn-helix (HH), and U-box domain. In contrast to nearly all homodimeric proteins, CHIP is asymmetric. To uncover the origins of asymmetry, we performed molecular dynamics simulations of dimer assembly. We determined that a CHIP monomer is most stable when the HH domain has an extended helix that supports intra-monomer TPR-U-box interaction, blocking the E2-binding surface of the U-box...
May 11, 2017: Scientific Reports
Seth H Weinberg, Devin B Mair, Christopher A Lemmon
The ability of cells to sense and respond to mechanical cues from the surrounding environment has been implicated as a key regulator of cell differentiation, migration, and proliferation. The extracellular matrix (ECM) is an oft-overlooked component of the interface between cells and their surroundings. Cells assemble soluble ECM proteins into insoluble fibrils with unique mechanical properties that can alter the mechanical cues a cell receives. In this study, we construct a model that predicts the dynamics of cellular traction force generation and subsequent assembly of fibrils of the ECM protein fibronectin (FN)...
May 9, 2017: Biophysical Journal
Yingying Zong, Bin Shao, Wenchen Xu, Bin Guo, Debin Shan
This paper reports the presence of tear strips on the surface of a Ti-22Al-25Nb alloy sheet stretched at 960 °C. The test piece reveals a "bamboo"-shaped pattern on its surface, which severely affects the quality of the alloy. Microstructure analysis indicates that the formation mechanism of the tear strip is related to both the rich α2 phase layer and the interfacial B2 phase dynamic recrystallization layer between the α2 phase layer and the substrate metal.
May 10, 2017: Scientific Reports
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