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Laura Wallard, Sophie Boulet, Olivier Cornu, Jean-Emile Dubuc, Philippe Mahaudens, Didier Postlethwaite, Maïté Van Cauter, Christine Detrembleur
BACKGROUND: The gait mechanism requires an efficient intersegmental coordination in order to ensure the displacement of the body while simultaneously maintaining the postural stability. However, intersegmental coordination may be disrupted by neurological or orthopaedic involvement, this increasing the metabolic cost associated with excessive or prolonged muscle co-contraction. RESEARCH QUESTION: Our aim was to evaluate and to understand how hip OA affects lower limbs coordination during gait by using the kinematic segmental covariation law method and predict the energy expenditure...
March 7, 2018: Gait & Posture
Chun-Yu Wang, Shuai Jiang, Yi-Rong Liu, Hui Wen, Zhongquan Wang, Ya-Juan Han, Teng Huang, Wei Huang
Ammonia and amines are important common trace atmospheric species that can enhance new particle formation (NPF) in the Earth's atmosphere. However, the synergistic effect of these two bases involving nucleation is still lacking. We studied the most stable geometric structures and thermodynamics of quaternary (NH3)(CH3NH2)(H2SO4)m(H2O)n (m = 1-3, n = 0-4) clusters at the PW91PW91/6-311++G(3df,3pd) level of theory for the first time. We find that the proton transfer from H2SO4 molecule to CH3NH2 molecule is easier than to NH3 molecule in the free or hydrated H2SO4-base clusters, and thus leads to the stability...
March 16, 2018: Journal of Physical Chemistry. A
Diyuan Zong, Zhen Yang, Yuanyuan Duan
The wetting kinetics of droplets on lyophilic pillar-arrayed substrates is the driving mechanism of several natural phenomena (e.g., insect capturing by Nepenthes) and many industrial technologies (e.g., gas-liquid separation). For a lyophilic pillar-arrayed surface, a fringe film is formed ahead of the contact line, resulting in distinct wetting kinetics, which needs further investigation. In this study, Si(100) substrates with square micropillars were used to investigate the early spreading of droplets on lyophilic pillar-arrayed surfaces through the droplet-spreading method...
March 16, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Matheus D Baldissera, Carine F Souza, Carla Cristina Zeppenfeld, Sharine Descovi, Aleksandro S da Silva, Bernardo Baldisserotto
The phosphotransfer network system, through the enzymes creatine kinase (CK), adenylate kinase (AK), and pyruvate kinase (PK), contributes to efficient intracellular energetic communication between cellular adenosine triphosphate (ATP) consumption and production in tissues with high energetic demand, such as cerebral tissue. Thus, the aim of this study was to evaluate whether aflatoxin B1 (AFB1 ) intoxication in diet negatively affects the cerebral phosphotransfer network related to impairment of cerebral ATP levels in silver catfish (Rhamdia quelen)...
March 15, 2018: Fish Physiology and Biochemistry
Ana P F Santos, Bianca M Souza, Tânia F C V Silva, Rodrigo P Cavalcante, Silvio C Oliveira, Amílcar Machulek, Rui A R Boaventura, Vítor J P Vilar
The mineralization of bio-recalcitrant humic acids (HAs) by a solar photo-Fenton (SPF) process was investigated in aqueous system, in order to understand its abatement in real high-HA content matrices, such as sanitary landfill leachates. SPF reactions were performed in tubular photoreactors with CPCs at lab-scale (simulated solar light) and pilot-scale (natural sunlight). Considering the experimental conditions selected for this work, the formation of insoluble HA-Fe3+ complexes was observed. Thus, to avoid HA precipitation, oxalic acid (Ox) was added, since Fe3+ -Ox complexes present a higher stability constant...
March 15, 2018: Environmental Science and Pollution Research International
Kian F Wong, James Teng, Michael W L Chee, Kinjal Doshi, Julian Lim
Mindfulness based training (MBT) is becoming increasingly popular as a means to improve general wellbeing through developing enhanced control over metacognitive processes. In this preliminary study, we tested a cohort of 36 nurses (mean age = 30.3, SD = 8.52; 2 male) who participated in an 8-week MBT intervention to examine the improvements in sustained attention and its energetic costs that may result from MBT. Changes in sustained attention were measured using the psychomotor vigilance task (PVT) and electroencephalography (EEG) was collected both during PVT performance, and during a brief period of meditation...
2018: Frontiers in Human Neuroscience
Shuai Zhang, Qinfu Liu, Hongfei Cheng, Feng Gao, Cun Liu, Brian J Teppen
Intercalation is the promising strategy to expand the interlayer region of kaolinite for their further applications. Herein, the adaptive biasing force (ABF) accelerated molecular dynamics simulations were performed to calculate the free energies involved in the kaolinite intercalation by dimethyl sulfoxide (DMSO). Additionally, the classical all atom molecular dynamics simulations were carried out to calculate the interfacial interactions between kaolinite interlayer surfaces and DMSO with the aim at exploring the underlying force that drives the DMSO to enter the interlayer space...
January 2018: Applied Clay Science
Adebayo A Adeleke, Yansun Yao
Experimental studies at finite Pressure-Temperature (P-T) conditions and a theoretical study at 0 K of the phase transition in lead sulphide (PbS) have been inconclusive. Many studies that have been done to understand structural transformation in PbS can broadly be classified into two main ideological streams-one with Pnma and another with Cmcm orthorhombic intermediate phase. To foster better understanding of this phenomenon, we present the result of the first-principles study of phase transition in PbS at finite temperature...
March 14, 2018: Journal of Chemical Physics
Christoph Schran, Felix Uhl, Jörg Behler, Dominik Marx
The design of accurate helium-solute interaction potentials for the simulation of chemically complex molecules solvated in superfluid helium has long been a cumbersome task due to the rather weak but strongly anisotropic nature of the interactions. We show that this challenge can be met by using a combination of an effective pair potential for the He-He interactions and a flexible high-dimensional neural network potential (NNP) for describing the complex interaction between helium and the solute in a pairwise additive manner...
March 14, 2018: Journal of Chemical Physics
Massimo Boninsegni
The momentum distribution and atomic kinetic energy of the two isotopes of helium in a liquid mixture at temperature T = 2 K are computed by quantum Monte Carlo simulations. Quantum statistics is fully included for4 He, whereas3 He atoms are treated as distinguishable. Comparison of theoretical estimates with a collection of the most recent experimental measurements shows reasonable agreement for the energetics of4 He and pure3 He. On the other hand, a significant discrepancy (already observed in previous studies) is reported between computed and measured values of the3 He kinetic energy in the mixture, especially in the limit of low3 He concentration...
March 14, 2018: Journal of Chemical Physics
F Calvo, E Yurtsever
A flexible and polarizable interatomic potential has been developed to model hydrogen clusters interacting with one hydrogen anion, (H2 )n H- , in a broad range of sizes n = 1-54 and parametrized against coupled cluster quantum chemical calculations. Using path-integral molecular dynamics simulations at 1 K initiated from the putative classical global minima, the equilibrium structures are found to generally rely on icosahedral shells with the hydrogen molecules pointing toward the anion, producing geometric magic numbers at sizes n = 12, 32, and 44 that are in agreement with recent mass spectrometry measurements...
March 14, 2018: Journal of Chemical Physics
Michael M Linden, J Philipp Wagner, Bastian Bernhardt, Marcus A Bartlett, Wesley D Allen, Peter R Schreiner
Disentangling internal and external effects is a key requirement for understanding conformational tunneling processes. Here we report the s-trans/s-cis tunneling rotamerization of carbonic acid monomethyl ester (1) under matrix isolation conditions and make comparisons to its parent carbonic acid (3). The observed tunneling rate of 1 is temperature independent in the 3-20 K range and accelerates when using argon instead of neon as the matrix material. The methyl group increases the effective half-life (τeff) of the energetically disfavored s-trans-conformer from 3-5 h for 3 to 11-13 h for 1...
March 15, 2018: Journal of Physical Chemistry Letters
Qingzhong Li, Hui-Li Xu, Steve Scheiner
HOX (X = Cl, Br, I, and At) can engage in either a H-bond (HB) or halogen bond (XB) with a base like HCN, NH3, and imidazole. While the former is energetically preferred for X=Cl and Br, it is the XB that is more stable for At, with I showing little preference. MgY2 forms a Mg-bond with the O atom of HOX, which grows stronger in the order X= Cl < Br < I < At and Y= F< Cl < Br. When all three molecules are combined together, both the Mg and the H/X bonds are cooperatively strengthened to a large degree...
March 15, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Matthew P Kroonblawd, Fabio Pietrucci, Antonino Marco Saitta, Nir Goldman
We demonstrate the capability of creating robust density functional tight binding (DFTB) models for chemical reactivity in prebiotic mixtures through force matching to short time scale quantum free energy estimates. Molecular dynamics using density functional theory (DFT) is a highly accurate approach to generate free energy surfaces for chemical reactions, but the extreme computational cost often limits the time scales and range of thermodynamic states that can feasibly be studied. In contrast, DFTB is a semi-empirical quantum method that affords up to a thousandfold reduction in cost and can recover DFT-level accuracy...
March 15, 2018: Journal of Chemical Theory and Computation
Thomas D Whitney, Michael I Sitvarin, Edward A Roualdes, Simon J Bonner, James D Harwood
Generalist predators are capable of selective foraging, but are predicted to feed in close proportion to prey availability to maximize energetic intake especially when overall prey availability is low. By extension, they are also expected to feed in a more frequency-dependent manner during winter compared to the more favorable foraging conditions during spring, summer and fall seasons. For 18 months, we observed the foraging patterns of forest-dwelling wolf spiders from the genus Schizocosa (Araneae: Lycosidae) using PCR-based gut-content analysis and simultaneously monitored the activity-densities of two common prey: springtails (Collembola) and flies (Diptera)...
March 15, 2018: Molecular Ecology
David B Medeiros, Leonardo Perez de Souza, Werner C Antunes, Wagner L Araújo, Danilo M Daloso, Alisdair R Fernie
Sucrose has long been thought to play an osmolytic role in stomatal opening. However, recent evidence supports the idea that the role of sucrose in this process is primarily energetic. Here we used a combination of stomatal aperture assays coupled with kinetic [U-13 C]-sucrose isotope labelling experiments to confirm that sucrose is degraded during light-induced stomatal opening and to define the fate of the C released from sucrose breakdown. We additionally show that addition of sucrose in the medium did not enhance light-induced stomatal opening...
March 15, 2018: Plant Journal: for Cell and Molecular Biology
Jiangbin Su, Xianfang Zhu
The nanoinstability of single crystal Si nanowire under electron beam irradiation was in-situ investigated at room temperature by transmission electron microscopy technique. It was observed that the Si nanowire amorphized preferentially from the surface towards the center with the increasing of electron dose. In contrast, in the center of the Si nanowire the amorphization seemed much more difficult accompanying with rotation of crystal grains and compression of d-spacing. Such a preferential amorphization as athermally induced by the electron beam irradiation can be well accounted for by our proposed concepts of nanocurvature effect and energetic beam-induced athermal activation effect, while the classical knock-on mechanism and the electron beam heating effect seem inadequate to explain these processes...
March 15, 2018: Nanotechnology
Mads Rosenkilde, Lisbeth Rygaard, Pernille Nordby, Lars Bo Nielsen, Bente Stallknecht
Exercise training and weight loss both reduce cardiovascular risk, but the independent importance of the two strategies is unclear. We aimed to investigate independent and combined effects of exercise training and weight loss on lipoproteins and dyslipidemia in overweight sedentary men. Sixty individuals were randomized to 12 weeks of endurance training (T), energy-reduced diet (D), training and energy increased diet (T-iD), or control (C). Equal energetic deficits (-600 kcal/day) were prescribed by exercise for T and caloric restriction for D...
March 15, 2018: Journal of Applied Physiology
Michael C Lucking, Weiyu Xie, Duk-Hyun Choe, Damien West, Toh-Ming Lu, S B Zhang
Interest in two-dimensional materials has exploded in recent years. Not only are they studied due to their novel electronic properties, such as the emergent Dirac fermion in graphene, but also as a new paradigm in which stacking layers of distinct two-dimensional materials may enable different functionality or devices. Here, through first-principles theory, we reveal a large new class of two-dimensional materials which are derived from traditional III-V, II-VI, and I-VII semiconductors. It is found that in the ultrathin limit the great majority of traditional binary semiconductors studied (a series of 28 semiconductors) are not only kinetically stable in a two-dimensional double layer honeycomb structure, but more energetically stable than the truncated wurtzite or zinc-blende structures associated with three dimensional bulk...
February 23, 2018: Physical Review Letters
Thai M Hoang, Rui Pan, Jonghoon Ahn, Jaehoon Bang, H T Quan, Tongcang Li
Nonequilibrium processes of small systems such as molecular machines are ubiquitous in biology, chemistry, and physics but are often challenging to comprehend. In the past two decades, several exact thermodynamic relations of nonequilibrium processes, collectively known as fluctuation theorems, have been discovered and provided critical insights. These fluctuation theorems are generalizations of the second law and can be unified by a differential fluctuation theorem. Here we perform the first experimental test of the differential fluctuation theorem using an optically levitated nanosphere in both underdamped and overdamped regimes and in both spatial and velocity spaces...
February 23, 2018: Physical Review Letters
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