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Shang Zhou, Hua Wang, Li Zhong, Guanghai Li
In this article Ca1-x TiO3 :xEu3+ single crystalline particles with a cubic morphology and average size of 248 to 815 nm were synthesized by a solvothermal method. The structural and optical properties of the Ca1-x TiO3 :xEu3+ cubes were investigated, the formation mechanism of the cubes were analyzed and discussed, and the influence of Eu doping content and cubic size on the photoluminescence were examined. The differences in the photoluminescence between Ca1-x TiO3 :xEu3+ cubic crystals and nanoparticles was analyzed...
January 17, 2018: Luminescence: the Journal of Biological and Chemical Luminescence
Piotr Aleksander Guńka, Michał Hapka, Michael Hanfland, Maciej Dranka, Grzegorz Chałasiński, Janusz Zachara
Investigations into the helium permeation of arsenolite, the cubic, molecular arsenic(III) oxide polymorph As₄O₆, were carried out in order to understand how and why arsenolite helium clathrate As₄O₆∙2He is formed. High-pressure synchrotron X-ray diffraction experiments on arsenolite single crystals revealed that the permeation of helium into non-porous arsenolite depends on the time during which the crystal is subjected to high pressure and on the crystal history. The single crystal was totally transformed into As₄O₆·2He within 45 h under 5 GPa...
January 17, 2018: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Charles Vlek
Recently, growing earthquake activity in the northeastern Netherlands has aroused considerable concern among the 600,000 provincial inhabitants. There, at 3 km deep, the rich Groningen gas field extends over 900 km2 and still contains about 600 of the original 2,800 billion cubic meters (bcm). Particularly after 2001, earthquakes have increased in number, magnitude (M, on the logarithmic Richter scale), and damage to numerous buildings. The man-made nature of extraction-induced earthquakes challenges static notions of risk, complicates formal risk assessment, and questions familiar conceptions of acceptable risk...
January 16, 2018: Risk Analysis: An Official Publication of the Society for Risk Analysis
Mohamad R Soltanian, Mohammad A Amooie, David R Cole, Thomas H Darrah, David E Graham, Susan M Pfiffner, Tommy J Phelps, Joachim Moortgat
In the context of geological carbon sequestration (GCS), carbon dioxide (CO2 ) is often injected into deep formations saturated with a brine that may contain dissolved light hydrocarbons, such as methane (CH4 ). In this multicomponent multiphase displacement process, CO2 competes with CH4 in terms of dissolution, and CH4 tends to exsolve from the aqueous into a gaseous phase. Because CH4 has a lower viscosity than injected CO2 , CH4 is swept up into a 'bank' of CH4 -rich gas ahead of the CO2 displacement front...
January 16, 2018: Ground Water
Shenglu Deng, Jianxi Zhao
Herein, homogeneous solutions of cationic gemini surfactants, alkanediyl-α,ω-bis(dimethyldodecylammonium bromide), referred to as 12-s-12 where s = 2, 4, 6, 8, and 10, in cyclohexane have been prepared with the help of sodium hexanoate (SH) or sodium laurate (SL). These surfactants self-assembled in cyclohexane to form various aggregating structures, which were characterised by small-angle X-ray scattering (SAXS) together with polarised microscopy observations. The results showed that 12-2-12/SH, where the gemini had the shortest spacer among this series, formed an inverse micellar cubic liquid crystalline phase of the Fd3m structure...
January 17, 2018: Soft Matter
Yu Wen, Dehong Xia
The purpose of this study is to provide scientific guidance for morphological control of nanoparticle synthesis by gas phase method. A universal thermodynamics model is developed to predict morphology of nanoparticles fabricated by inert gas condensation method. By the use of the model, morphologies of aluminum nanocrystals are predicted under various preparation conditions. There are two kinds of energies that determine the formation of nanoparticles morphology jointly, which are Gibbs free energy for nanoparticles and energy variation during the process...
January 17, 2018: Nanotechnology
M H M Nascimento, M K K D Franco, F Yokaichyia, E de Paula, C B Lombello, D R de Araujo
In this study, we reported the hyaluronic acid (HA) on supramolecular structure of Pluronic F-127 (PLF-127) and/or Pluronic F-108 (PLF-127) hydrogels, as well as their effects on release mechanisms, looking forward their application as lidocaine (LDC) drug-delivery systems in arthroplastic surgeries. We have studied the HA-micelle interaction using Dynamic Light Scattering (DLS), the micellization and sol-gel transition processes by Differential Scanning Calorimetry (DSC) and Rheology., of PL-based hydrogels and...
January 12, 2018: International Journal of Biological Macromolecules
Guy M Bernard, Roderick E Wasylishen, Christopher I Ratcliffe, Victor V Terskikh, Qichao Wu, Jillian M Buriak, Tate C Hauger
In light of the intense recent interest in the methylammonium lead halides, CH3NH3PbX3 (X = Cl, Br and I) as sensitizers for photovoltaic cells, the dynamics of the methylammonium (MA) cation in these perovskite salts has been reinvestigated as a function of temperature via 2H, 14N and 207Pb NMR spectroscopy. In the cubic phase of all three salts, the MA cation undergoes pseudo-isotropic tumbling (ps time scale). For example, the correlation time, τ2, for the C-N axis of the iodide salt is 0.85 ± 0.30 ps at 330 K...
January 16, 2018: Journal of Physical Chemistry. A
Xiaofan Xu, Wei Wang, Dongliang Liu, Dandan Hu, Tao Wu, Xianhui Bu, Pingyun Feng
The cubic ZnS structure type and the size-dependent properties of related nanoparticles are of both fundamental and technological importance. Yet, it remains a challenge to synthesize large atom-precise clusters of this structure type. Currently, only supertetrahedral clusters with 4, 10, 20, and 35 metal sites (denoted as T2, T3, T4, and T5, respectively) are known. Because the synthesis of T5 in 2002, numerous synthetic efforts targeting larger clusters only resulted in T2-T5 clusters in various compositions and intercluster connectivity, with T6 (56 metal and 84 anion sites) being elusive...
January 16, 2018: Journal of the American Chemical Society
Karim Aissou, Muhammad Mumtaz, Alberto Alvarez-Fernandez, Jean Mercat, Ségolène Antoine, Gilles Pécastaings, Virginie Ponsinet, Cécile Dobrzynski, Guillaume Fleury, Georges Hadziioannou
Nanotemplates derived from the self-assembly of AB-type block copolymers provide an elegant route to achieve well-defined metallic dot arrays, even if the variety of pattern symmetries is restricted due to the limited number of structures offered by microphase separated diblock copolymers. A strategy that relies on the use of complex network structures accessible through the self-assembly of linear ABC-type terpolymers is presented for the formation of metallic nanodots arrays with "outside-the-box" symmetries...
January 16, 2018: Macromolecular Rapid Communications
Jiaye Li, Howard Z Ma, Gavin E Reid, Alison J Edwards, Yuning Hong, Jonathan M White, Roger J Mulder, Richard A J O'Hair
We report new structural motifs for Cu nanoclusters that conceptually represent seed crystals for large face-centred cubic (FCC) crystal growth. Kinetically controlled syntheses, high resolution mass spectrometry experiments for determination of the dication formulae and crystallographic characterisation were carried out for [Cu18 H16 (DPPE)6 ][BF4 ][Cl] (DPPE=bis(diphenylphosphino)ethane) and [Cu16 H14 (DPPA)6 ][(BF4 )2 ] (DPPA=bis(diphenylphosphino)amine) polyhydrido nanoclusters, which feature the unprecedented bifrustum and frustum metal-core architecture in metal nanoclusters...
January 16, 2018: Chemistry: a European Journal
L J Bridge, J Mead, E Frattini, I Winfield, G Ladds
Theoretical models of G protein-coupled receptor (GPCR) concentration-response relationships often assume an agonist producing a single functional response via a single active state of the receptor. These models have largely been analysed assuming steady-state conditions. There is now much experimental evidence to suggest that many GPCRs can exist in multiple receptor conformations and elicit numerous functional responses, with ligands having the potential to activate different signalling pathways to varying extents - a concept referred to as biased agonism, functional selectivity or pluri-dimensional efficacy...
January 11, 2018: Journal of Theoretical Biology
Amreen Bano, N K Gaur
A variety of theoretical and experimental works have reported several potential applications of MoS2 monolayer based heterostructures (HSs) such as light emitting diodes, photodetectors and field effect transistors etc. In the present work, we have theoretically performed as a model case study, MoS2 monolayer deposited over insulating SrTiO3 (001) to study the band alignment at TiO2 termination. The interfacial characteristics are found to be highly dependent on the interface termination. With an insulating oxide material, a significant band gap (0...
January 15, 2018: Scientific Reports
Francesco Caddeo, Danilo Loche, Maria F Casula, Anna Corrias
Copper ferrite, belonging to the wide and technologically relevant class of spinel ferrites, was grown in the form of t-CuFe2O4 nanocrystals within a porous matrix of silica in the form of either an aerogel or a xerogel, and compared to a bulk sample. Extended X-ray absorption fine structure (EXAFS) spectroscopy revealed the presence of two different sub-lattices within the crystal structure of t-CuFe2O4, one tetragonal and one cubic, defined by the Cu2+ and Fe3+ ions respectively. Our investigation provides evidence that the Jahn-Teller distortion, which occurs on the Cu2+ ions located in octahedral sites, does not affect the coordination geometry of the Fe3+ ions, regardless of their location in octahedral or tetrahedral sites...
January 15, 2018: Scientific Reports
Zongyao Li, Yujin Cho, Xiang Li, Xinyu Li, Akihisa Aimi, Yoshiyuki Inaguma, Jose Antonio Alonso, Maria Teresa Fernandez-Diaz, Jiaqiang Yan, Michael C Downer, Graeme Henkelman, John B Goodenough, Jianshi Zhou
Perovskite oxides hosting ferroelectricity are particularly important materials for modern technologies. The ferroelectric transition in the well-known oxides BaTiO3 and PbTiO3 is realized by softening of a vibration mode in the cubic perovskite structure. For most perovskite oxides, octahedral-site tilting systems are developed to accommodate the bonding mismatch due to a geometric tolerance factor t = (A-O)/[√2(B-O)] < 1. In the absence of cations having lone-pair electrons, e.g. Bi3+ and Pb2+, all simple and complex A-site and B-site ordered perovskite oxides with a t < 1 show a variety of tilting systems and none of them become ferroelectric...
January 15, 2018: Journal of the American Chemical Society
Daniel Fritsch
Spinel ferrites in general show a rich interplay of structural, electronic, and magnetic properties. Here, we particularly focus on zinc ferrite (ZFO), which has been observed experimentally to crystallise in the cubic <i>normal</i> spinel structure. However, its magnetic ground state is still under dispute. In addition, some unusual magnetic properties in ZFO thin films or nanostructures have been explained by a possible partial cation inversion and a different magnetic interaction between the two cation sublattices of the spinel structure compared to the crystalline bulk material...
January 15, 2018: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Babak Mohammadzadeh Asl, Ali Mohades Deylami
In recent years, high resolution adaptive minimum variance-based beamformers have been successfully applied to medical ultrasound imaging to improve its resolution and contrast, simultaneously. However, these improvements come at the cost of much more computational complexity in comparison to the non-adaptive delay-and-sum beamformer. The computational overhead mainly results from the L×L covariance matrix inversion needed for computation of the adaptive weights, the complexity of which is cubic with the subarray size, O(L3)...
January 4, 2018: Ultrasonics
Vadim B Warshavsky, David M Ford, Peter A Monson
The stability of the body-centered cubic (bcc) solid phase of classical hard spheres is of intrinsic interest and is also relevant to the development of perturbation theories for bcc solids of other model systems. Using canonical ensemble Monte Carlo, we simulated systems initialized in a perfect bcc lattice at various densities in the solid region. We observed that the systems rapidly evolved into one of four structures that then persisted for the duration of the simulation. Remarkably, one of these structures was identified as cI16, a cubic crystalline structure with 16 particles in the unit cell, which has recently been observed experimentally in lithium and sodium solids at high pressures...
January 14, 2018: Journal of Chemical Physics
Bircan Erbas, Mitra Jazayeri, Katrina A Lambert, Constance H Katelaris, Luke A Prendergast, Rachel Tham, M Jeannette Parrodi, Janet Davies, Ed Newbigin, Michael J Abramson, Shyamali C Dharmage
BACKGROUND: In the context of increased asthma exacerbations associated with climatic changes such as thunderstorm asthma, interest in establishing the link between pollen exposure and asthma hospital admissions has intensified. Here, we systematically reviewed and performed a meta-analysis of studies on pollen and ED attendance. METHODS: A search for studies with appropriate search strategy in Medline, Embase, Web of Science and CINAHL was conducted. Each study was assessed for quality and risk of bias...
January 13, 2018: Allergy
Wen-Hsuan Kuan, Li-Ting Kao, Jing-Yun Wang, Kuei-Huei Lin
We report a passively mode-locked erbium-doped fiber laser with pulse widths switchable from 473 fs to 76.8 ns, where the fundamental mode-locking, noise-like pulse, nanosecond mode-locking, and dual-width mode-locking (DML) are obtained by adjusting a polarization controller. Co-existence of femto- and nano-second pulses in DML is attributed to the gain balancing. Analytic modeling of the fiber laser with the cubic-quintic Ginzburg-Landau equation is presented, in which the pulse widths are calculated as functions of dispersion, self-phase modulation (SPM), cubic saturable absorption (SA), and quintic SA...
January 15, 2018: Optics Letters
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