Read by QxMD icon Read

Dynamic stretching

Brooke Huisman, Masoud Hoore, Gerhard Gompper, Dmitry A Fedosov
Von Willebrand factor (VWF) is a key protein in hemostasis as it mediates adhesion of blood platelets to a site of vascular injury. A proper distribution of VWF lengths is important for normal functioning of hemostatic processes, because a diminished number of long VWF chains may significantly limit blood clotting and lead to bleeding, while an abundant number of long VWFs may result in undesired thrombotic events. VWF size distribution is controlled by ADAMTS13 protease, which can cleave VWF chains beyond a critical shear rate when the chains are stretched enough such that cleavage sites become accessible...
July 19, 2017: Medical Engineering & Physics
Kai Szuttor, Tamal Roy, Steffen Hardt, Christian Holm, Jens Smiatek
We use mesoscopic lattice-Boltzmann/molecular dynamics simulations to study the stretching behavior of a single tethered polymer in micro- and nanochannels. In particular, we are interested in the connection between fluid flow properties and the force on the polymer chain. An analytical expression for the stretching force is proposed, which linearly depends on the number of monomers and the boundary shear rate. In agreement with theory, the numerical findings reveal that the influence of hydrodynamic interactions can be ignored, which is also supported by results of additional Langevin dynamics simulations...
July 21, 2017: Journal of Chemical Physics
Xiancai Jiang, Nanping Xiang, Jinquan Wang, Yulai Zhao, Linxi Hou
Development of bio-based hydrogels with good mechanical properties is of great importance for their excellent biocompatibility and biodegradability. In this paper, chitosan (CS) based double network (DN) hydrogel was prepared by dissolving CS in AlCl3·6H2O aqueous solution instead of acetic acid solution. After dissolving acrylic amide (AM), acrylic acid (AA), N, N'-methylenebisacrylamide and 2-hydroxy-4'-(2-hydoxyethoxy)-2-methylpropiophenone were added into the CS/Al(3+) solution and the CS/PAMAA-Al(3+) DN hydrogel was prepared by UV polymerization...
October 1, 2017: Carbohydrate Polymers
Yong-Tao Ma, Xinyou Ma, Anyang Li, Hua Guo, Li Yang, Jiaxu Zhang, William L Hase
Direct dynamics simulations were performed to study the SN2 double inversion mechanism SN2-DI, with retention of configuration, for the F(-) + CH3I reaction. Previous simulations identified a transition state (TS) structure, i.e. TS0, for the SN2-DI mechanism, including a reaction path. However, intrinsic reaction coordinate (IRC) calculations from TS0 show it is a proton transfer (PT) TS connected to the F(-)HCH2I SN2 pre-reaction complex and the FHCH2I(-) proton transfer post-reaction complex. Inclusion of TS0 in the SN2-DI mechanism would thus involve non-IRC atomistic dynamics...
July 20, 2017: Physical Chemistry Chemical Physics: PCCP
Sayan Mondal, Mrinalini Puranik
We report deep UV initiated excited state dynamics of the canonical nucleobase adenine (Ade) through Resonance Raman (RR) intensity analysis. RR spectra of Ade at excitation wavelengths throughout the Bb absorption band in the 210-230 nm wavelength range are measured and subsequently converted to scattering cross-sections. The time-dependent wave packet (TDWP) formalism has been employed for self-consistent simulations of the resulting wavelength dependent Raman excitation profiles (REP) and absorption spectrum of Ade...
July 20, 2017: Physical Chemistry Chemical Physics: PCCP
Ehsan Nematian-Ardestani, Viwan Jarerattanachat, Prafulla Aryal, Mark S P Sansom, Stephen J Tucker
The TREK-2 (KCNK10) K2P potassium channel can be regulated by variety of polymodal stimuli including pressure. In a recent study, we demonstrated that this mechanosensitive K(+) channel responds to changes in membrane tension by undergoing a major structural change from its 'down' state to the more expanded 'up' state conformation. These changes are mostly restricted to the lower part of the protein within the bilayer, but are allosterically coupled to the primary gating mechanism located within the selectivity filter...
July 19, 2017: Channels
Rupesh K Mishra, Lee J Hubble, Aida Martín, Rajan Kumar, Abbas Barfidokht, Jayoung Kim, Mustafa M Musameh, Ilias L Kyratzis, Joseph Wang
A flexible glove-based electrochemical biosensor with highly stretchable printed electrode system has been developed as a wearable point-of-use screening tool for defense and food security applications. This disposable-mechanically robust "lab-on-a-glove" integrates a stretchable printable enzyme-based biosensing system and active surface for swipe sampling on different fingers, and is coupled with a compact electronic interface for electrochemical detection and real-time wireless data transmission to a smartphone device...
April 28, 2017: ACS Sensors
Jae Yoon Shin, Steven A Yamada, Michael D Fayer
Supported ionic liquid membranes (SILMs) are porous membranes impregnated with ionic liquids (ILs) and used as advanced carbon capture materials. Here, two-dimensional infrared (2D IR) and IR polarization selective pump-probe (PSPP) spectroscopies were used to investigate CO2 reorientation and spectral diffusion dynamics in SILMs. The SILM contained 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonly)imide in the poly(ether sulfone) membrane with average pore size of ~350 nm. Two ensembles of CO2 were observed in the SILM, one in the IL phase in the membrane pores and the other in the supporting membrane polymer...
July 19, 2017: Journal of the American Chemical Society
Chi Ma, Tuo Ji, Christopher G Robertson, R Rajeshbabu, Jiahua Zhu, Yalin Dong
The debate regarding the possible molecular origins of the Mullins effect has been ongoing since its discovery. Molecular dynamics (MD) simulations were carried out to elucidate the underlying mechanism of the Mullins effect. For the first time, the key characteristics associated with the Mullins effect, including (a) the majority of stress softening occurring in the first stretch, (b) continuous softening with stress increase, (c) a permanent set, and (d) recovery with heat treatment, are captured by molecular modeling...
July 18, 2017: Physical Chemistry Chemical Physics: PCCP
Sangeeta Kundu, Sanchita Mukherjee, Dhananjay Bhattacharyya
Genomic DNA of higher organisms exists as extremely long polymers, while in bacteria and other lower organisms it is circular with no terminal base pairs. Temperature-induced melting of the DNA double helix by localized strand separation has been unattainable by molecular dynamic simulations due to more rapid fraying of the terminal base pairs in oligomeric DNA. However, local-sequence-dependent unfolding of the DNA double helix is extremely important for understanding various biochemical phenomena, and can be addressed by simulating a model polymeric DNA duplex...
August 2017: Journal of Molecular Modeling
Wilbert J Smit, Fujie Tang, Yuki Nagata, M Alejandra Sanchez, Taisuke Hasegawa, Ellen H G Backus, Mischa Bonn, Huib J Bakker
We study the signatures of the OH stretch vibrations at the basal surface of ice using heterodyne-detected sum-frequency generation and molecular dynamics simulations. At 150 K, we observe 7 distinct modes in the sum-frequency response, five of which have an analogue in the bulk, and two pure surface-specific modes can be identified at higher frequencies (~3530 and ~3700 cm(-1)). The band at ~3530 cm(-1) has not been reported previously. Using molecular dynamics simulations we find that the ~3530 cm(-1) band contains contributions from OH stretch vibrations of both fully coordinated interfacial water molecules and of water molecules with two donor and one acceptor hydrogen-bond...
July 17, 2017: Journal of Physical Chemistry Letters
Oluwaseun O Mesele, Ward H Thompson
Empirical maps are presented for the OH stretching vibrations in neat alcohols in which the relevant spectroscopic quantities are expressed in terms of the electric field exerted on the hydrogen atom by the surrounding liquid. It is found, by examination of the four lowest linear alcohols, methanol, ethanol, n-propanol, and n-butanol, that a single map can be used for alcohols with different alkyl groups. This "universal" map is in very good agreement with maps optimized for the individual alcohols, but differs from those previously developed for water...
July 17, 2017: Journal of Physical Chemistry. A
Mohammad Alzubi, Sandra Arias, Iria Louzao, Emilio Quiñoá, Ricardo Riguera, Félix Freire
A precise tuning of the four possible states of a helix (P/M helical sense and stretched/compressed helical backbone) is attained by controlling the complexation between Li(+) and a poly(phenylacetylene) that bears amide, ester and phenyl ring functionalities at the pendant group. Depending on the MeOH ratio that is present as a cosolvent, different coordination sites are involved in interactions leading to complexes I-III, each one with a characteristic structure (tri-, bi-, and unipodal) and an associated helical state...
July 17, 2017: Chemical Communications: Chem Comm
Min You, Liyuan Liu, Wenkai Zhang
Covalently bound diazo groups are frequently found in biomolecular substrates. The C[double bond, length as m-dash]N[double bond, length as m-dash]N asymmetric stretching vibration (νas) of the diazo group has a large extinction coefficient and appears in an uncongested spectral region. To evaluate the solvatochromism of the C[double bond, length as m-dash]N[double bond, length as m-dash]N νas band for studying biomolecules, we recorded the infrared (IR) spectra of a diazo model compound, 2-diazo-3-oxo-butyric acid ethyl ester, in different solvents...
July 17, 2017: Physical Chemistry Chemical Physics: PCCP
Mariam A Ameer, Qassim I Muaidi
CONTEXT: The effect of acute static stretch (ASS) on the lower limb RT has been recently questioned to decrease the risk of falling and injuries in situations requiring a rapid reaction, as in the cases of balance disturbance. OBJECTIVE: The main purpose of this study was to detect the effect of ASS on the lower limb RT by using virtual reality device. DESIGN: Two Group Control Group design. SETTING: Research laboratory...
July 17, 2017: Journal of Sport Rehabilitation
Ilya V Pobelov, Kasper Primdal Lauritzen, Koji Yoshida, Anders Jensen, Gábor Mészáros, Karsten W Jacobsen, Mikkel Strange, Thomas Wandlowski, Gemma C Solomon
While one might assume that the force to break a chemical bond gives a measure of the bond strength, this intuition is misleading. If the force is loaded slowly, thermal fluctuations may break the bond before it is maximally stretched, and the breaking force will be less than the bond can sustain. Conversely, if the force is loaded rapidly it is more likely that the maximum breaking force is measured. Paradoxically, no clear differences in breaking force were observed in experiments on gold nanowires, despite being conducted under very different conditions...
July 17, 2017: Nature Communications
Xiangjian Shen, Zhaojun Zhang, Dong H Zhang
As one benchmark system of CH4 dissociation on the Ni(111) surface, it is of great significance to explore the role of each degree of freedom (DOF) of reactant CH4 in its first C-H bond dissociation from quantum dynamics simulations. Here, the influence of the CH stretching DOF of methyl limited in C3v symmetry is quantitatively investigated as well as the important role of azimuth. We calculated the sticking probabilities, S0, of ground state (GS) CH4 dissociation on a rigid Ni(111) surface by performing some seven-dimensional to nine-dimensional (9D) quantum dynamics simulations based on one highly accurate and fifteen-dimensional (15D) ab initio potential energy surface which we recently developed...
July 14, 2017: Journal of Chemical Physics
So-Yeon Kim, Jeongmook Lee, Sang Kyu Kim
In this work, we have investigated nonadiabatic dynamics in the vicinity of conical intersections for predissociation reactions of partially deuterated thioanisole molecules: C6H5S-CH2D and C6H5S-CHD2. Each isotopomer has two distinct rotational conformers according to the geometrical position of D or H of the methyl moiety with respect to the molecular plane for C6H5S-CH2D or C6H5S-CHD2, respectively, as spectroscopically characterized in our earlier report [J. Lee, S.-Y. Kim and S. K. Kim, J. Phys. Chem. A, 2014, 118, 1850]...
July 14, 2017: Physical Chemistry Chemical Physics: PCCP
Gaojian Lin, Prashant Chandrasekaran, Cunjing Lv, Qiuting Zhang, Yichao Tang, Lin Han, Jie Yin
Smart window has immense potential for energy saving in architectural and vehicular applications, while most studies focus on the tunability of single property of optical transmittance. Here we explore harnessing dynamically tunable hierarchical wrinkles for design of a potential multifunctional smart window with combined structural color and water droplet transport control. The self-similar hierarchical wrinkles with both nanoscale and microscale features are generated on a pre-strained poly(dimethylsiloxane) (PDMS) elastomer through sequential strain release and multi-step oxygen plasma treatment...
July 13, 2017: ACS Applied Materials & Interfaces
Deping Hu, Yan Fang Liu, Andrzej L Sobolewski, Zhenggang Lan
The nonadiabatic dynamics of keto isocytosine in the gas phase has been investigated using the on-the-fly trajectory surface hopping method based on two electronic-structure methods: SA-CASSCF and ADC(2). The results estimate an excited-state lifetime of around 1000 fs at the SA-CASSCF level, while a much shorter lifetime of 250-350 fs is obtained at the ADC(2) level. Although three conical intersections (CIs) (Ethyl. I, Ethyl. II and C[double bond, length as m-dash]O stretching) are relevant to the nonadiabatic decay of keto isocytosine, their contributions to the nonadiabatic decay are highly dependent on the electronic-structure methods employed in the dynamics simulation...
July 12, 2017: Physical Chemistry Chemical Physics: PCCP
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"