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Confined Spaces

Jian Feng Zhu, Shao Wei Liao, Shu Fang Li, Quan Xue
In this paper, a new spoof surface plasmon polaritons (SPPs) based transmission line (TL) with semi-open structure is proposed, which is implemented on a single-layer substrate with metallized via holes planted on a ground plane. The electromagnetic (EM) power propagates along it in the form of controlled slow surface wave, which is the same with its existing counterparts. The proposed TL can adjust the degree of EM energy confinement, and thus balance its performance in every characteristic, in particular attenuation and interference...
August 14, 2017: Scientific Reports
Sarah Schuster, Timothy Krüger, Ines Subota, Sina Thusek, Brice Rotureau, Andreas Beilhack, Markus Engstler
The highly motile and versatile protozoan pathogen Trypanosoma brucei undergoes a complex life cycle in the tsetse fly. Here we introduce the host insect as an expedient model environment for microswimmer research, as it allows examination of microbial motion within a diversified, secluded and yet microscopically tractable space. During their week-long journey through the different microenvironments of the fly´s interior organs, the incessantly swimming trypanosomes cross various barriers and confined surroundings, with concurrently occurring major changes of parasite cell architecture...
August 15, 2017: ELife
Vahid Satarifard, Maziar Heidari, Samaneh Mashaghi, Sander J Tans, Mohammad Reza Ejtehadi, Alireza Mashaghi
Spatial confinement limits the conformational space accessible to biomolecules but the implications for bimolecular topology are not yet known. Folded linear biopolymers can be seen as molecular circuits formed by intramolecular contacts. The pairwise arrangement of intra-chain contacts can be categorized as parallel, series or cross, and has been identified as a topological property. Using molecular dynamics simulations, we determine the contact order distributions and topological circuits of short semi-flexible linear and ring polymer chains with a persistence length of lp under a spherical confinement of radius Rc...
August 14, 2017: Nanoscale
Siyuan Dai, Qiong Ma, Yafang Yang, Jeremy Rosenfeld, Michael Goldflam, Alex McLeod, Zhiyuan Sun, Trond Andersen, Zhe Fei, Mengkun Liu, Yinming Shao, Kenji Watanabe, Takashi Taniguchi, Mark H Thiemens, Fritz Keilmann, Pablo Jarillo-Herrero, Michael M Fogler, D N Basov
We investigated phonon-polaritons in hexagonal boron nitride - a naturally hyperbolic van der Waals material - by means of the scattering-type scanning near-field optical microscopy. Real-space nano-images we have obtained detail how the polaritons are launched when the light incident on a thin hexagonal boron nitride slab is scattered by various intrinsic and extrinsic inhomogeneities, including sample edges, metallic nanodisks deposited on its top surface, random defects, and surface impurities. The scanned tip of the near-field microscope is itself a polariton launcher whose efficiency proves to be superior to all the other types of polariton launchers we studied...
August 14, 2017: Nano Letters
Rui Hao, Yunshan Fan, Bo Zhang
The electrochemical interface is an ultrathin interfacial region between the electrode surface and the electrolyte solution and is often characterized by numerous dynamic processes, such as solvation and desolvation, heterogeneous electron transfer, molecular adsorption and desorption, diffusion, and surface rearrangement. Many of these processes are driven and modulated by the presence of a large interfacial potential gradient. The study and better understanding of the electrochemical interface is important for designing better electrochemical systems where their applications may include batteries, fuel cells, electrocatalytic water splitting, corrosion protection, and electroplating...
August 11, 2017: Journal of the American Chemical Society
Brian Crook, Stephen Stagg, Alison Bowry, Gillian Frost
Hydrogen sulphide gas (H2S) produced by sulphate reducing bacteria (SRB) in stored animal slurry is highly toxic and, if emitted into poorly ventilated confined spaces, can build up to concentrations capable of causing asphyxiation. Therefore it is important to understand factors influencing H2S emission from slurry. Powdered gypsum (hydrated calcium sulphate) may be used as animal bedding and, if it enters slurry systems, could be metabolised by SRB and further increase H2S generation. Cattle slurry and cattle bedding collected from farms was used in laboratory-scale experiments sealed in 20litre vessels fitted with mechanical stirrers...
August 6, 2017: Science of the Total Environment
Yoram Zarai, Michael Margaliot, Anatoly B Kolomeisky
Natural phenomena frequently involve a very large number of interacting molecules moving in confined regions of space. Cellular transport by motor proteins is an example of such collective behavior. We derive a deterministic compartmental model for the unidirectional flow of particles along a one-dimensional lattice of sites with nearest-neighbor interactions between the particles. The flow between consecutive sites is governed by a "soft" simple exclusion principle and by attracting or repelling forces between neighboring particles...
2017: PloS One
Lalit Bansal, Saptarshi Basu, Suman Chakraborty
Tiny concentrations of suspended particles may alter the behavior of an evaporating droplet remarkably, leading to partially viscous and partially elastic dynamical characteristics. This, in turn, may lead to some striking mechanical instabilities, such as buckling and rupture. Here, we report certain non-trivial implications of the consequent morpho-dynamics (macro to nano scales), when such an evaporating droplet is encapsulated in a confined environment. Compared to unconfined scenario, we report non-intuitive suppression of rupturing beyond a critical confinement...
August 9, 2017: Scientific Reports
Chen Ji, Fan Fan, Xuelin Lou
Phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2) signaling is transient and spatially confined in live cells. How this pattern of signaling regulates transmitter release and hormone secretion has not been addressed. We devised an optogenetic approach to control PI(4,5)P2 levels in time and space in insulin-secreting cells. Combining this approach with total internal reflection fluorescence microscopy, we examined individual vesicle-trafficking steps. Unlike long-term PI(4,5)P2 perturbations, rapid and cell-wide PI(4,5)P2 reduction in the plasma membrane (PM) strongly inhibits secretion and intracellular Ca(2+) concentration ([Ca(2+)]i) responses, but not sytaxin1a clustering...
August 8, 2017: Cell Reports
Rong-Guang Xu, Yuan Xiang, Yongsheng Leng
Understanding the squeeze out behaviors of liquid films at nanometer scale in an atomic force microscope (AFM) has been a significant interest since the 1990s. We carry out all-atom static-mode AFM simulations in a liquid-vapor molecular dynamics ensemble to investigate the solvation force oscillation and squeeze out mechanisms of a confined linear dodecane fluid between a gold AFM tip and a mica substrate. Solvation force oscillations are found to be associated with the layering transition of the liquid film and unstable jumps of the AFM tip...
August 7, 2017: Journal of Chemical Physics
Qingyun Li, Carl I Steefel, Young-Shin Jun
Wellbore cement deterioration is critical for wellbore integrity and the safety of CO2 storage in geologic formations. Our previous experimental work highlighted the importance of the portlandite (CH)-depleted zone and the surface dissolution zone in the CO2-attacked cement. In this study, we simulated numerically the evolution of the CH-depleted zone and the dissolution of the cement surfaces utilizing a reduced dimension (1D) reactive transport model. The approach shows that three nanoscale effects are important and had to be incorporated in a continuum-scale model to capture experimental observations: First, it was necessary to account for the fact that secondary CaCO3 precipitation does not fill the pore space completely, with the result that acidic brine continues to diffuse through the carbonated zone to form a CH-depleted zone...
August 7, 2017: Environmental Science & Technology
Yuliya V Fedoseeva, Andrey S Orekhov, Galina N Chekhova, Victor O Koroteev, Mikhail A Kanygin, Boris V Senkovskiy, Andrey Chuvilin, Daniele Pontiroli, Mauro Riccò, Lyubov G Bulusheva, Alexander V Okotrub
Single-walled carbon nanotubes (SWCNTs) possessing a confined inner space protected by chemically resistant shells are promising for delivery, storage, and desorption of various compounds, as well as carrying out specific reactions. Here, we show that SWCNTs interact with molten mercury dichloride (HgCl2) and guide its transformation into dimercury dichloride (Hg2Cl2) in the cavity. The chemical state of host SWCNTs remains almost unchanged except for a small p-doping from the guest Hg2Cl2 nanocrystals. The density functional theory calculations reveal that the encapsulated HgCl2 molecules become negatively charged and start interacting via chlorine bridges when local concentration increases...
August 14, 2017: ACS Nano
Yonggang Zheng, Qian Li, Jiayong Zhang, Hongfei Ye, Hong Wu Zhang, Luming Shen
Based on molecular dynamics simulations, tensile mechanical properties and plastic deformation mechanisms of nano-twinned Cu//Ag multilayered materials are investigated in this work. Simulation results show that, due to the stronger strengthening effect of the twin boundary than both the cube-on-cube and hetero-twin interfaces between Cu and Ag layers, the strength increases with the increase of layer thickness for nano-twinned Cu//Ag multilayered materials with a constant twin spacing, while it decreases with the increase of layer thickness for twin-free ones...
August 7, 2017: Nanotechnology
Fatemeh Jalali, Felix Ellett, Daniel Irimia
The widespread bacterial resistance to a broad range of antibiotics necessitates rapid antibiotic susceptibility testing before effective treatment could start in the clinic. Among resistant bacteria, Staphylococcus aureus is one of the most important, and Methicillin-resistant (MRSA) strains are a common cause of life threatening infections. However, standard susceptibility testing for S. aureus is time consuming and thus the start of effective antibiotic treatment is often delayed. To circumvent the limitations of current susceptibility testing systems, we designed an assay that enables measurements of bacterial growth with higher spatial and temporal resolution than standard techniques...
June 2017: Technology
Heejung S Jung, Michael L Grady, Tristan Victoroff, Arthur L Miller
Prior studies demonstrate that air recirculation can reduce exposure to nanoparticles in vehicle cabins. However when people occupy confined spaces, air recirculation can lead to carbon dioxide (CO2) accumulation which can potentially lead to deleterious effects on cognitive function. This study proposes a fractional air recirculation system for reducing nanoparticle concentration while simultaneously suppressing CO2 levels in the cabin. Several recirculation scenarios were tested using a custom-programmed HVAC (heat, ventilation, air conditioning) unit that varied the recirculation door angle in the test vehicle...
July 2017: Atmospheric Environment
D J Schlossberg, G M Bodner, M W Bongard, M G Burke, R J Fonck, J M Perry, J A Reusch
Access to and characterization of sustained, toroidally confined plasmas with a very high plasma-to-magnetic pressure ratio (β_{t}), low internal inductance, high elongation, and nonsolenoidal current drive is a central goal of present tokamak plasma research. Stable access to this desirable parameter space is demonstrated in plasmas with ultralow aspect ratio and high elongation. Local helicity injection provides nonsolenoidal sustainment, low internal inductance, and ion heating. Equilibrium analyses indicate β_{t} up to ∼100% with a minimum |B| well spanning up to ∼50% of the plasma volume...
July 21, 2017: Physical Review Letters
T Liuti, S Smith, P M Dixon
BACKGROUND: Equine maxillary cheek teeth apical infections are a significant disorder because of frequent spread of infection to the supporting bones. The accuracy of computed tomographic imaging (CT) of this disorder has not been fully assessed. OBJECTIVES: To compare the radiographic and CT findings in horses diagnosed with maxillary cheek teeth apical infections with pathological findings in the extracted teeth to assess the accuracy of these imaging techniques...
August 3, 2017: Equine Veterinary Journal
Jun Bao, Noritatsu Tsubaki
Tandem catalytic reaction is a promising strategy to improve the utilization efficiency of energy and resources. The conventional hybrid catalysts cannot readily realize the precisely controlled synthesis of target products due to the unrestricted, open reaction environment. Assembling the hybrid catalyst with multiple active sites into core-shell structured capsule catalyst is one of the most effective ways to enhance the selectivity of desired products during a tandem catalysis process, because the core-shell structure offers a space-confined reaction field and synergistic effect...
August 3, 2017: Chemical Record: An Official Publication of the Chemical Society of Japan ... [et Al.]
Sudhir Kumar, Jakub Jagielski, Nikolaos Kallikounis, Young-Hoon Kim, Christoph Wolf, Florian Jenny, Tian Tian, Corinne J Hofer, Yu-Cheng Chiu, Wendelin J Stark, Tae-Woo Lee, Chih-Jen Shih
Pure green light-emitting diodes (LEDs) are essential for realizing an ultrawide color gamut in next-generation displays, as is defined by the recommendation (Rec.) 2020 standard. However, because the human eye is more sensitive to the green spectral region, it is not yet possible to achieve an ultrapure green electroluminescence (EL) with a sufficiently narrow bandwidth that covers >95% of the Rec. 2020 standard in the CIE 1931 color space. Here, we demonstrate efficient, ultrapure green EL based on the colloidal two-dimensional (2D) formamidinium lead bromide (FAPbBr3) hybrid perovskites...
August 8, 2017: Nano Letters
A S Jacobsen, F Binda, C Cazzaniga, J Eriksson, A Hjalmarsson, M Nocente, M Salewski, G Tardini
Future fusion reactors are foreseen to be heated by the energetic alpha particles produced in fusion reactions. For this to happen, it is important that the energetic ions are sufficiently confined. In present day fusion experiments, energetic ions are primarily produced using external heating systems such as neutral beam injection and ion cyclotron resonance heating. In order to diagnose these fast ions, several different fast-ion diagnostics have been developed and implemented in the various experiments around the world...
July 2017: Review of Scientific Instruments
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