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Confined Spaces

L F Delgado-Aparicio, J Maddox, N Pablant, K Hill, M Bitter, J E Rice, R Granetz, A Hubbard, J Irby, M Greenwald, E Marmar, K Tritz, D Stutman, B Stratton, P Efthimion
A compact multi-energy soft x-ray camera has been developed for time, energy and space-resolved measurements of the soft-x-ray emissivity in magnetically confined fusion plasmas. Multi-energy soft x-ray imaging provides a unique opportunity for measuring, simultaneously, a variety of important plasma properties (Te, nZ, ΔZeff, and ne,fast). The electron temperature can be obtained by modeling the slope of the continuum radiation from ratios of the available brightness and inverted radial emissivity profiles over multiple energy ranges...
November 2016: Review of Scientific Instruments
Colin D Paul, Panagiotis Mistriotis, Konstantinos Konstantopoulos
Time-lapse, deep-tissue imaging made possible by advances in intravital microscopy has demonstrated the importance of tumour cell migration through confining tracks in vivo. These tracks may either be endogenous features of tissues or be created by tumour or tumour-associated cells. Importantly, migration mechanisms through confining microenvironments are not predicted by 2D migration assays. Engineered in vitro models have been used to delineate the mechanisms of cell motility through confining spaces encountered in vivo...
December 2, 2016: Nature Reviews. Cancer
Maxime Theillard, Roberto Alonso-Matilla, David Saintillan
Recent experimental studies have shown that confinement can profoundly affect self-organization in semi-dilute active suspensions, leading to striking features such as the formation of steady and spontaneous vortices in circular domains and the emergence of unidirectional pumping motions in periodic racetrack geometries. Motivated by these findings, we analyze the two-dimensional dynamics in confined suspensions of active self-propelled swimmers using a mean-field kinetic theory where conservation equations for the particle configurations are coupled to the forced Navier-Stokes equations for the self-generated fluid flow...
December 1, 2016: Soft Matter
Nicole Wyttenbach, Martin Kuentz
This note is about the glass-forming ability (GFA) of drugs marketed as amorphous solid dispersions or as pure amorphous compounds. A thermoanalytical method was complemented with an in silico study, which made use of molecular properties that were identified earlier as being relevant for GFA. Thus, molar volume together with effective numbers of torsional bonds and hydrogen bonding were used to map drugs that are as amorphous products on the market either as solid dispersion of without co-processed carrier as amorphous drug in a solid dosage form...
November 27, 2016: European Journal of Pharmaceutics and Biopharmaceutics
Tony Low, Andrey Chaves, Joshua D Caldwell, Anshuman Kumar, Nicholas X Fang, Phaedon Avouris, Tony F Heinz, Francisco Guinea, Luis Martin-Moreno, Frank Koppens
In recent years, enhanced light-matter interactions through a plethora of dipole-type polaritonic excitations have been observed in two-dimensional (2D) layered materials. In graphene, electrically tunable and highly confined plasmon-polaritons were predicted and observed, opening up opportunities for optoelectronics, bio-sensing and other mid-infrared applications. In hexagonal boron nitride, low-loss infrared-active phonon-polaritons exhibit hyperbolic behaviour for some frequencies, allowing for ray-like propagation exhibiting high quality factors and hyperlensing effects...
November 28, 2016: Nature Materials
Erja Portegijs, Merja Rantakokko, Anne Viljanen, Taina Rantanen, Susanne Iwarsson
PURPOSE: We studied whether entrance-related environmental barriers, perceived and objectively recorded, were associated with moving out-of-home daily in older people with and without limitations in lower extremity performance. METHODS: Cross-sectional analyses of the "Life-space mobility in old age" cohort including 848 community-dwelling 75-90-year-old of central Finland. Participants reported their frequency of moving out-of-home (daily vs. 0-6 times/week) and perceived entrance-related environmental barriers (yes/no)...
November 19, 2016: Archives of Gerontology and Geriatrics
Lila Bouzar, Martin Michael Müller, Pierre Gosselin, Igor M Kulić, Hervé Mohrbach
We theoretically study the conformations of a helical semi-flexible filament confined to a flat surface. This squeezed helix exhibits a variety of unexpected shapes resembling circles, waves or spirals depending on the material parameters. We explore the conformation space in detail and show that the shapes can be understood as the mutual elastic interaction of conformational quasi-particles. Our theoretical results are potentially useful to determine the material parameters of such helical filaments in an experimental setting...
November 2016: European Physical Journal. E, Soft Matter
C Ritter, A Provino, P Manfrinetti, A K Pathak
An investigation on the ground state magnetism of CeScSi, CeScGe (tetragonal CeScSi-type, tI12, space group I4/mmm) by temperature-dependent powder neutron diffraction has been carried out, as debated and controversial data regarding the low temperature magnetic behaviours of these two compounds were reported. Our studies reveal that, while cooling, long-range magnetic ordering in CeScSi and CeScGe takes place by a two-step process. A first transition leads to a magnetic structure with the Ce moments aligned ferromagnetically onto two neighbouring tetragonal basal a-b planes of the CeScSi-type structure; the double layers are then antiferromagnetically coupled to each other along the c-axis...
November 24, 2016: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Milad Haghani, Majid Sarvi, Zahra Shahhoseini, Maik Boltes
How humans resolve non-trivial tradeoffs in their navigational choices between the social interactions (e.g., the presence and movements of others) and the physical factors (e.g., spatial distances, route visibility) when escaping from threats in crowded confined spaces? The answer to this question has major implications for the planning of evacuations and the safety of mass gatherings as well as the design of built environments. Due to the challenges of collecting behavioral data from naturally-occurring evacuation settings, laboratory-based virtual-evacuation experiments have been practiced in a number of studies...
2016: PloS One
Kirtikumar B Jadhav, Claudia Stein, Oliwia Makarewicz, Gabriele Pradel, Roman J Lichtenecker, Holger Sack, Stefan H Heinemann, Hans-Dieter Arndt
The d-/l-peptide gramicidin A (gA) is well known as a pivotal ion channel model and shows a broad spectrum of bioactivities such as antibiosis, antimalarial activity, as well as hemolysis. We applied inter-chain disulfide bonds to constrain the conformational freedom of gA into parallel and antiparallel dimeric topologies. Albeit the constructs were not found to be monoconformational, CD- and IR-spectroscopic studies suggested that this strategy indeed restricted the conformational space of the d-/l-peptide construct, and that β-helical secondary structures prevail...
November 9, 2016: Bioorganic & Medicinal Chemistry
Kartik Jain, Geir Ringstad, Per-Kristian Eide, Kent-André Mardal
Obstruction to the cerebrospinal fluid (CSF) outflow caused by the herniation of cerebellar tonsils as a result of Chiari malformation type I leads to altered CSF hydrodynamics. This contribution explores the minutest characteristics of the CSF hydrodynamics in cervical subarachnoid spaces (SAS) of a healthy subject and two Chiari patients by performing highly resolved direct numerical simulation. The Lattice Boltzmann method is used for the simulations due to its scalability on modern supercomputers that allow us to simulate up to  ∼ 10(9) cells while resolving the Kolmogorov microscales...
November 10, 2016: International Journal for Numerical Methods in Biomedical Engineering
Amer Alizadeh, Moran Wang
Uncovering electroosmosis around an inhomogeneously acquired charge spherical particle in a confined space could provide detailed insights into its broad applications from biology to geology. In the present study, we developed a direct simulation method with the effects of inhomogeneously acquired charges on the particle surface considered, which has been validated by the available analytical and experimental data. Modeling results reveal that the surface charge and zeta potential, which are acquired through chemical interactions, strongly depend on the local solution properties and the particle size...
November 10, 2016: Electrophoresis
Chang Liu, Chao Zhou, Wei Wang, H P Zhang
Synthetic microswimmers are envisioned to be useful in numerous applications, many of which occur in tightly confined spaces. It is therefore important to understand how confinement influences swimmer dynamics. Here we study the motility of bimetallic microswimmers in linear and curved channels. Our experiments show swimmer velocities increase, up to 5 times, with the degree of confinement, and the relative velocity increase depends weakly on the fuel concentration and ionic strength in solution. Experimental results are reproduced in a numerical model which attributes the swimmer velocity increase to electrostatic and electrohydrodynamic boundary effects...
November 4, 2016: Physical Review Letters
Juan A Faraldos, Daniel J Grundy, Oscar Cascon, Stefano Leoni, Marc W van der Kamp, Rudolf K Allemann
The sesquiterpene cyclase aristolochene synthase from Penicillium roquefortii (PR-AS) has evolved to catalyse with high specificity (92%) the conversion of farnesyl diphosphate (FDP) to the bicyclic hydrocarbon (+)-aristolochene, the natural precursor of several fungal toxins. Here we report that PR-AS converts the unnatural FDP isomer 7-methylene farnesyl diphosphate to (+)-aristolochene via the intermediate 7-methylene germacrene A. Within the confined space of the enzyme's active site, PR-AS stabilises the reactive conformers of germacrene A and 7-methylene germacrene A, respectively, which are protonated by the same active site acid (most likely HOPPi) to yield the shared natural bicyclic intermediate eudesmane cation, from which (+)-aristolochene is then generated...
November 17, 2016: Chemical Communications: Chem Comm
Gil Iosilevskii, Yannis P Papastamatiou
Sharks have a distinctive shape that remained practically unchanged through hundreds of millions of years of evolution. Nonetheless, there are variations of this shape that vary between and within species. We attempt to explain these variations by examining the partial derivatives of the cost of transport of a generic shark with respect to buoyancy, span and chord of its pectoral fins, length, girth and body temperature. Our analysis predicts an intricate relation between these parameters, suggesting that ectothermic species residing in cooler temperatures must either have longer pectoral fins and/or be more buoyant in order to maintain swimming performance...
October 2016: Royal Society Open Science
Jiri Weiss, Luisa Maria Cabalín, J Javier Laserna
The present work focuses on the influence of the angle of observation on the emission signal from copper plasmas. Plasma plumes have been generated inside a home-made chamber consisting of two parallel glass windows spaced by 2.5 mm. This chamber allows observing plasma plumes from different collection angles throughout their perimeter, spanning from 20° to 80° with respect to the surface of the Cu target. In order to minimize the observed volume of the plasma, measurements were made from the closest distance possible through a metallic hollow tube...
November 16, 2016: Applied Spectroscopy
Kristin J Redmond, Simon S Lo, Scott G Soltys, Yoshiya Yamada, Igor J Barani, Paul D Brown, Eric L Chang, Peter C Gerszten, Samuel T Chao, Robert J Amdur, Antonio A F De Salles, Matthias Guckenberger, Bin S Teh, Jason Sheehan, Charles R Kersh, Michael G Fehlings, Moon-Jun Sohn, Ung-Kyu Chang, Samuel Ryu, Iris C Gibbs, Arjun Sahgal
OBJECTIVE Although postoperative stereotactic body radiation therapy (SBRT) for spinal metastases is increasingly performed, few guidelines exist for this application. The purpose of this study is to develop consensus guidelines to promote safe and effective treatment for patients with spinal metastases. METHODS Fifteen radiation oncologists and 5 neurosurgeons, representing 19 centers in 4 countries and having a collective experience of more than 1300 postoperative spine SBRT cases, completed a 19-question survey about postoperative spine SBRT practice...
November 11, 2016: Journal of Neurosurgery. Spine
Chanil Jeon, Youngkyun Jung, Bae-Yeun Ha
A chain molecule can be entropically collapsed in a crowded medium in a free or confined space. Here, we present a unified view of how molecular crowding collapses a flexible polymer in three distinct spaces: free, cylindrical, and (two-dimensional) slit-like. Despite their seeming disparities, a few general features characterize all these cases, even though the ϕc-dependence of chain compaction differs between the two cases: a > ac and a < ac, where ϕc is the volume fraction of crowders, a is the monomer size, and ac is the crowder size...
November 11, 2016: Soft Matter
Ángel Cantín, M Victoria Gomez, Antonio de la Hoz
Diels-Alder cycloaddition between cyclopentadiene and p-benzoquinone has been studied in the confined space of a pure silica zeolite Beta and the impact on reaction rate due to the concentration effect within the pore and diffusion limitations are discussed. Introduction of Lewis or Brønsted acid sites on the walls of the zeolite strongly increases the reaction rate. However, contrary to what occurs with mesoporous molecular sieves (MCM-41), Beta zeolite does not catalyse the retro-Diels-Alder reaction, resulting in a highly selective catalyst for the cycloaddition reaction...
2016: Beilstein Journal of Organic Chemistry
Anika C Juhl, Artur Schneider, Boris Ufer, Torsten Brezesinski, Jürgen Janek, Michael Fröba
Hollow carbon spheres (HCS) with a nanoporous shell are promising for the use in lithium-sulfur batteries because of the large internal void offering space for sulfur and polysulfide storage and confinement. However, there is an ongoing discussion whether the cavity is accessible for sulfur. Yet no valid proof of cavity filling has been presented, mostly due to application of unsuitable high-vacuum methods for the analysis of sulfur distribution. Here we describe the distribution of sulfur in hollow carbon spheres by powder X-ray diffraction and Raman spectroscopy along with results from scanning electron microscopy and nitrogen physisorption...
2016: Beilstein Journal of Nanotechnology
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