45,538 results match your criteria Lattice Degeneration


Light-Induced Activation of Forbidden Exciton Transition in Strongly Confined Perovskite Quantum Dots.

ACS Nano 2018 Dec 6. Epub 2018 Dec 6.

We report the strong light-induced activation of forbidden exciton transition in CsPbBr perovskite quantum dots mediated by the symmetry-breaking polaron that modifies the optical selection rule of the confined exciton transition. The activated forbidden transition results in an intense pump-induced absorption in the transient absorption spectra above the bandgap, where the original parity-forbidden transition was located. In contrast to many other semiconductor quantum dots, photoexcitation of exciton in CsPbBr quantum dots creates a sufficiently large perturbation via lattice-distorting polaron, which turns on the formally forbidden transition. Read More

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December 2018
4 Reads
12.881 Impact Factor

Experimental and theoretical evidences for the ice regime in planar artificial spin ices.

J Phys Condens Matter 2019 Jan;31(2):025301

Laboratory of Spintronics and Nanomagnetism (LabSpiN), Departamento de Física, Universidade Federal de Viçosa, 36570-900, Viçosa, Minas Gerais, Brazil.

In this work, we explore a kind of geometrical effect in the thermodynamics of artificial spin ices (ASI). In general, such artificial materials are athermal. Here, We demonstrate that geometrically driven dynamics in ASI can open up the panorama of exploring distinct ground states and thermally magnetic monopole excitations. Read More

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January 2019
1 Read

On the role of magnesium in a LiF:Mg,Ti thermoluminescent dosimeter.

J Phys Condens Matter 2019 Jan;31(2):025502

Instituto de Física, Universidad Nacional Autónoma de México, 04510 Coyoacan Mexico City, Mexico.

LiF doped with Mg and Ti is the most widely used thermoluminescent (TL) dosimeter for a large variety of applications. It has been argued that the Mg dopant is the most important defect in the TL process. Besides the common F-centre defects in LiF, optical absorption measurements have suggested the presence of Mg-related absorption bands at 380 nm (3. Read More

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January 2019

Transverse and longitudinal spin-fluctuations in INVAR FeNi.

J Phys Condens Matter 2019 Jan;31(2):025802

ISIS Neutron and Muon Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 0QX, United Kingdom.

The presence of spin-fluctuations deep within the ordered state of ferromagnetic [Formula: see text] alloy [Formula: see text] has long been suspected but seldom directly observed. Inhomogeneities of one type or another have been cited as important in stabilizing [Formula: see text] behaviour-either longitudinal spin-fluctuations associated with the [Formula: see text]-state (local environment) model or transverse magnetisation arising from non-collinear spin structures. In this study we employ small-angle neutron scattering with neutron polarization analysis to distinguish between the two possibilities. Read More

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January 2019
2 Reads

Magnetic, thermal, and neutron diffraction studies of a coordination polymer: bis(glycolato)cobalt(ii).

Dalton Trans 2018 Dec 6. Epub 2018 Dec 6.

General Education, Faculty of Science and Technology, Seikei University, 3-3-1 Kichijoji-kita machi, Musashino 180-8633, Japan.

The two-dimensional quadratic lattice magnet, bis(glycolato)cobalt(ii) ([Co(HOCH2CO2)2]), showed antiferromagnetic ordering at 15.0 K and an abrupt increase in magnetisation at H = 22 600 Oe and 2 K, thereby acting as a metamagnet. Heat capacity measurements revealed that the associated entropy change ΔS around the transition temperature was evaluated to be 6. Read More

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December 2018
1 Read

Biomaterial-Based "Structured Opals" with Programmable Combination of Diffractive Optical Elements and Photonic Bandgap Effects.

Adv Mater 2018 Dec 6:e1805312. Epub 2018 Dec 6.

Department of Biomedical Engineering, Tufts University, 4 Colby Street, Medford, MA, 02155, USA.

Naturally occurring iridescent systems produce brilliant color displays through multiscale, hierarchical assembly of structures that combine reflective, diffractive, diffusive, or absorbing domains. The fabrication of biopolymer-based, hierarchical 3D photonic crystals through the use of a topographical templating strategy that allows combined optical effects derived from the interplay of predesigned 2D and 3D geometries is reported here. This biomaterials-based approach generates 2D diffractive optics composed of 3D nanophotonic lattices that allow simultaneous control over the reflection (through the 3D photonic bandgap) and the transmission (through 2D diffractive structuring) of light with the additional utility of being constituted by a biocompatible, implantable, edible commodity textile material. Read More

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December 2018
1 Read

Special features of monolayer characteristics of N-alkanoyl substituted threonine amphiphiles.

Phys Chem Chem Phys 2018 Dec 6. Epub 2018 Dec 6.

Max Planck Institute of Colloids and Interfaces, D-14424 Potsdam/Golm, Germany.

The monolayers of N-alkanoyl substituted threonine amphiphiles, similar to those of other N-alkanoyl-substituted amino acid amphiphiles, point to substantial differences in the main characteristics compared to usual amphiphilic monolayers. π-A measurements of the enantiomeric and racemic forms of N-alkanoyl-substituted threonine monolayers with C16 and C18 chain lengths reveal that, independent of the alkyl chain length, all compression curves are located above the corresponding decompression curves. A theoretical model developed for the kinetics of two-dimensional condensation of Langmuir monolayers can describe this behavior concluding the attachment of monomers to large aggregates. Read More

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December 2018
1 Read

Transformation between meron and skyrmion topological spin textures in a chiral magnet.

Nature 2018 12 5;564(7734):95-98. Epub 2018 Dec 5.

RIKEN Center for Emergent Matter Science (CEMS), Wako, Japan.

Crystal lattices with tetragonal or hexagonal structure often exhibit structural transitions in response to external stimuli. Similar behaviour is anticipated for the lattice forms of topological spin textures, such as lattices composed of merons and antimerons or skyrmions and antiskyrmions (types of vortex related to the distribution of electron spins in a magnetic field), but has yet to be verified experimentally. Here we report real-space observations of spin textures in a thin plate of the chiral-lattice magnet CoZnMn, which exhibits in-plane magnetic anisotropy. Read More

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December 2018
1 Read

Seamless lateral graphene p-n junctions formed by selective in situ doping for high-performance photodetectors.

Nat Commun 2018 Dec 5;9(1):5168. Epub 2018 Dec 5.

State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, 865 Changning Road, Shanghai, 200050, P.R. China.

Lateral graphene p-n junctions are important since they constitute the core components in a variety of electronic/photonic systems. However, formation of lateral graphene p-n junctions with a controllable doping levels is still a great challenge due to the monolayer feature of graphene. Herein, by performing selective ion implantation and in situ growth by dynamic chemical vapor deposition, direct formation of seamless lateral graphene p-n junctions with spatial control and tunable doping is demonstrated. Read More

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December 2018

Direct van der Waals Epitaxy of Crack-Free AlN Thin Film on Epitaxial WS₂.

Materials (Basel) 2018 Dec 4;11(12). Epub 2018 Dec 4.

Research and Development Center for Solid State Lighting, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China.

Van der Waals epitaxy (vdWE) has drawn continuous attention, as it is unlimited by lattice-mismatch between epitaxial layers and substrates. Previous reports on the vdWE of III-nitride thin film were mainly based on two-dimensional (2D) materials by plasma pretreatment or pre-doping of other hexagonal materials. However, it is still a huge challenge for single-crystalline thin film on 2D materials without any other extra treatment or interlayer. Read More

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December 2018

Study of Size Effect on Microstructure and Mechanical Properties of AlSi10Mg Samples Made by Selective Laser Melting.

Materials (Basel) 2018 Dec 4;11(12). Epub 2018 Dec 4.

Institute of Advanced Structure Technology, Beijing Institute of Technology, Beijing 100081, China.

The macroscopic mechanical performance of additive manufactured structures is essential for the design and application of multiscale microlattice structure. Performance is affected by microstructure and geometrical imperfection, which are strongly influenced by the size of the struts in selective laser melting (SLM) lattice structures. In this paper, the effect of size on microstructure, geometrical imperfection, and mechanical properties was systemically studied by conducting experimental tests. Read More

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December 2018
2 Reads

Additive and Substractive Surface Structuring by Femtosecond Laser Induced Material Ejection and Redistribution.

Materials (Basel) 2018 Dec 4;11(12). Epub 2018 Dec 4.

Laboratoire Hubert Curien, UMR 5516 CNRS, Université de Lyon, Université Jean Monnet, 42000 Saint-Etienne, France.

A novel additive surface structuring process is devised, which involves localized, intense femtosecond laser irradiation. The irradiation induces a phase explosion of the material being irradiated, and a subsequent ejection of the ablative species that are used as additive building blocks. The ejected species are deposited and accumulated in the vicinity of the ablation site. Read More

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December 2018

Supercooling and Nucleation of Fatty Acids: Influence of Thermal History on the Behavior of the Liquid Phase.

J Phys Chem B 2018 Dec 3. Epub 2018 Dec 3.

Saturated fatty acids are an exceptionally important class of liquids, used in many consumer products and suggested as phase change materials (PCMs) for thermal energy storage, in part because they crystallize with minimal supercooling. Here we investigate fatty acid nucleation to understand why crystallization is so facile, as a step toward identifying potential mechanisms for the suppression of supercooling in other PCMs. We find that fatty acid supercooling can be induced only if the liquid is first heated above a material-dependent threshold temperature. Read More

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December 2018

High-Pressure Synthesis, Crystal Structure, Chemical Bonding, and Ferroelectricity of LiNbO-Type LiSbO.

Inorg Chem 2018 Dec 3. Epub 2018 Dec 3.

Institute of Materials Structure Science , High Energy Accelerator Research Organization , 1-1 Oho , Tsukuba , Ibaraki 305-0801 , Japan.

A polar LiNbO (LN)-type oxide LiSbO was synthesized by a high-temperature heat treatment under a pressure of 7.7 GPa and found to exhibit ferroelectricity. The crystal structural refinement using the data of synchrotron powder X-ray diffraction and neutron diffraction and the electronic structure calculation of LN-type LiSbO suggest a covalent-bonding character between Sb and O. Read More

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December 2018
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Tension-Induced Raman Enhancement of Graphene Membranes in the Stretched State.

Small 2018 Dec 3:e1804337. Epub 2018 Dec 3.

State Key Laboratory of Mechanical System and Vibration, School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.

The intensity ratio of the 2D band to the G band, I /I , is a good criterion in selecting high quality monolayer graphene samples; however, the evaluation of the ultimate value of I /I for intrinsic monolayer graphene is a challenging yet interesting issue. Here, an interesting tension-induced Raman enhancement phenomenon is reported in supported graphene membranes, which show a transition from the corrugated state to the stretched state in the vicinity of wells. The I /I of substrate-supported graphene membranes near wells are significantly enhanced up to 16. Read More

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December 2018

Biomolecular force fields: where have we been, where are we now, where do we need to go and how do we get there?

J Comput Aided Mol Des 2018 Nov 30. Epub 2018 Nov 30.

Department of Chemistry, University of Massachusetts, Amherst, MA, 01003, USA.

In this perspective, we review the theory and methodology of the derivation of force fields (FFs), and their validity, for molecular simulations, from their inception in the second half of the twentieth century to the improved representations at the end of the century. We examine the representations of the physics embodied in various force fields, their accuracy and deficiencies. The early days in the 1950s and 60s saw FFs first introduced to analyze vibrational spectra. Read More

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November 2018

Predicting the afterglow duration in persistent phosphors: a validated approach to derive trap depth distributions.

Phys Chem Chem Phys 2018 Dec 3. Epub 2018 Dec 3.

LumiLab, Department of Solid State Sciences, Ghent University, Ghent, Belgium. and Center for Nano- and Biophotonics (NB-Photonics), Ghent University, Ghent, Belgium.

Persistent phosphors are increasingly investigated due to their potential applications in various fields, such as safety signage, dosimetry and in vivo imaging. These materials act as optical batteries that store and gradually release energy supplied during optical charging. As the energy is stored, or 'trapped', at specific defect sites in the host lattice, a clear understanding of the defects and trapping mechanisms in these materials is important for systematic improvement of their properties. Read More

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December 2018

Fast kinetics of multivalent intercalation chemistry enabled by solvated magnesium-ions into self-established metallic layered materials.

Nat Commun 2018 Nov 30;9(1):5115. Epub 2018 Nov 30.

Helmholtz Institute Ulm (HIU), Helmholtzstraße 11, D-89081, Ulm, Germany.

Rechargeable magnesium batteries are one of the most promising candidates for next-generation battery technologies. Despite recent significant progress in the development of efficient electrolytes, an on-going challenge for realization of rechargeable magnesium batteries remains to overcome the sluggish kinetics caused by the strong interaction between double charged magnesium-ions and the intercalation host. Herein, we report that a magnesium battery chemistry with fast intercalation kinetics in the layered molybdenum disulfide structures can be enabled by using solvated magnesium-ions ([Mg(DME)]). Read More

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November 2018

Trivalent RING Assembly on Retroviral Capsids Activates TRIM5 Ubiquitination and Innate Immune Signaling.

Cell Host Microbe 2018 Nov 13. Epub 2018 Nov 13.

MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, UK. Electronic address:

TRIM5 is a RING domain E3 ubiquitin ligase with potent antiretroviral function. TRIM5 assembles into a hexagonal lattice on retroviral capsids, causing envelopment of the infectious core. Concomitantly, TRIM5 initiates innate immune signaling and orchestrates disassembly of the viral particle, yet how these antiviral responses are regulated by capsid recognition is unclear. Read More

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November 2018

Dispersion and Structure Analysis of Nanocrystalline Ti-ZrO₂ Composite Powder for Biomedical Applications.

J Nanosci Nanotechnol 2019 May;19(5):2799-2806

Institute of Materials Science, University of Silesia in Katowice, 41-500 Chorzów, Poland.

Titanium and titanium alloys are widely employed in biomedical applications but these alloys have unsatisfactory tribological properties because of their low hardness. Much better biomaterials for hard tissue replacement implants may be acquired by the preparation of titanium composites. Therefore, the connection of excellent biocompatibility and bioactivity of ZrO₂ ceramics with good properties of titanium is considered to be a promising approach for the fabrication of more perfect hard tissue replacement implants. Read More

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Structure and Mechanical Properties of the New Ti30Ta20Nb Biomedical Alloy.

J Nanosci Nanotechnol 2019 May;19(5):2556-2566

Institute of Materials Science, University of Silesia in Katowice, 41-500 Chorzów, Poland.

In order to better understand the relationship between parameters of a mechanical alloying process and microstructure, especially the structure of porosity, some research and studies were carried out. The current study investigates the possibility to prepare the porous materials by mechanical alloying and annealing. A high-energy ball-milling process in the planetary ball mill Fritch PULVERISETTE 7 premium line was used for the solid-state synthesis of the single phase powders for titanium based biomedical alloy. Read More

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Differential capacitance of ionic liquids according to lattice-gas mean-field model with nearest-neighbor interactions.

J Chem Phys 2018 Nov;149(20):204703

Department of Physics, North Dakota State University, Fargo, North Dakota 58108, USA.

The Bragg-Williams free energy is used to incorporate nearest-neighbor interactions into the lattice gas model of a solvent-free ionic liquid near a planar electrode. We calculate the differential capacitance from solutions of the mean-field consistency relation, arriving at an explicit expression in the limit of a weakly charged electrode. The two additional material parameters that appear in the theory-the degree of nonideality and the resistance to concentration changes of each ion type-give rise to different regimes that we identify and discuss. Read More

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November 2018

Quantumness and state boundaries hidden in supercritical helium-4: A path integral centroid molecular dynamics study.

J Chem Phys 2018 Nov;149(20):204504

Division of Chemistry, Graduate School of Humanities and Sciences, Nara Women's University, Nara 630-8506, Japan.

Isothermal-isobaric path integral centroid molecular dynamics simulations were conducted for fluid He at more than 600 state points in the proximity of the critical point to reveal the detailed states and relevant quantumness underlying the supercritical state. Through intensive analyses of the thermodynamic, dynamic, and quantum properties, we revealed the hidden state boundaries that separate the liquid-like and gas-like states in the supercritical region of this fluid. The Widom line, defined as the locus of the maxima of isobaric heat capacity , is also the quantum boundary at which there are changes in the isobaric temperature-dependence of the quantum wavelength, , i. Read More

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November 2018

NaMnZr(PO): A High-Voltage Cathode for Sodium Batteries.

J Am Chem Soc 2018 Dec 2. Epub 2018 Dec 2.

Sodium batteries have been regarded as promising candidates for large-scale energy storage application, provided cathode hosts with high energy density and long cycle life can be found. Herein, we report NASICON-structured Na3MnZr(PO4)3 as a cathode for sodium batteries that exhibits an electrochemical performance superior to those of oth-er manganese phosphate cathodes reported in the literature. Both the Mn4+/Mn3+ and Mn3+/Mn2+ redox couples are re-versibly accessed in Na3MnZr(PO4)3, providing high discharge voltage plateaus at 4. Read More

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December 2018
3 Reads

Dynamics of DNA Origami Lattice Formation at Solid-Liquid Interfaces.

ACS Appl Mater Interfaces 2018 Dec 3. Epub 2018 Dec 3.

The self-organized formation of regular patterns is not only a fascinating topic encountered in a multitude of natural and artificial systems, but also presents a versatile and powerful route towards large-scale nanostructure assembly and materials synthesis. The hierarchical, interface-assisted assembly of DNA origami nanostructures into regular, 2D lattices represents a particularly promising example, as the resulting lattices may exhibit an astonishing degree of order and can be further utilized as masks in molecular lithography. Here, we thus investigate the development of order in such 2D DNA origami lattices assembled on mica surfaces by employing in-situ high-speed atomic force microscopy (AFM) imaging. Read More

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December 2018

Determination of the Elasticity Modulus of 3D-Printed Octet-Truss Structures for Use in Porous Prosthesis Implants.

Materials (Basel) 2018 Nov 29;11(12). Epub 2018 Nov 29.

Escola Tècnica Superior d'Enginyeria Industrial de Barcelona (ETSEIB), Avinguda Diagonal, 647, 08028 Barcelona, Spain.

In tissue engineering, scaffolds can be obtained by means of 3D printing. Different structures are used in order to reduce the stiffness of the solid material. The present article analyzes the mechanical behavior of octet-truss microstructures. Read More

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November 2018
1 Read

Improved Mechanical Properties and Energy Absorption of BCC Lattice Structures with Triply Periodic Minimal Surfaces Fabricated by SLM.

Materials (Basel) 2018 Nov 29;11(12). Epub 2018 Nov 29.

State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China.

The triply periodic minimal surface (TPMS) method is a novel approach for lattice design in a range of fields, such as impact protection and structural lightweighting. In this paper, we used the TPMS formula to rapidly and accurately generate the most common lattice structure, named the body centered cubic (BCC) structure, with certain volume fractions. TPMS-based and computer aided design (CAD) based BCC lattice structures with volume fractions in the range of 10⁻30% were fabricated by selective laser melting (SLM) technology with Ti⁻6Al⁻4V and subjected to compressive tests. Read More

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November 2018

Two Phase Transitions in the Two-Dimensional Nematic Three-Vector Model with No Quasi-Long-Range Order: Monte Carlo Simulation of the Density of States.

Phys Rev Lett 2018 Nov;121(21):217801

Centre for Modelling, Simulation and Design, University of Hyderabad, Hyderabad 500046, India.

The presence of stable topological defects in a two-dimensional (d=2) liquid crystal model allowing molecular reorientations in three dimensions (n=3) was largely believed to induce a defect-mediated Berzenskii-Kosterlitz-Thouless-type transition to a low temperature phase with quasi-long-range order. However, earlier Monte Carlo (MC) simulations could not establish certain essential signatures of the transition, suggesting further investigations. We study this model by computing its equilibrium properties through MC simulations, based on the determination of the density of states of the system. Read More

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November 2018

Chiral Spin Density Wave and d+id Superconductivity in the Magic-Angle-Twisted Bilayer Graphene.

Phys Rev Lett 2018 Nov;121(21):217001

School of Physics, Beijing Institute of Technology, Beijing 100081, China.

We model the newly synthesized magic-angle-twisted bilayer graphene superconductor with two p_{x,y}-like Wannier orbitals on the superstructure honeycomb lattice, where the hopping integrals are constructed via the Slater-Koster formulism by symmetry analysis. The characteristics exhibited in this simple model are well consistent with both the rigorous calculations and experiment observations. A van Hove singularity and Fermi-surface (FS) nesting are found in the doping levels relevant to the correlated insulator and unconventional superconductivity revealed experimentally, based on which we identify the two phases as weak-coupling FS instabilities. Read More

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November 2018

Proton Mass Decomposition from the QCD Energy Momentum Tensor.

Phys Rev Lett 2018 Nov;121(21):212001

Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.

We report results on the proton mass decomposition and also on related quark and glue momentum fractions. The results are based on overlap valence fermions on four ensembles of N_{f}=2+1 domain wall fermion configurations with three lattice spacings and three volumes, and several pion masses including the physical pion mass. With fully nonperturbative renormalization (and universal normalization on both quark and gluon), we find that the quark energy and glue field energy contribute 32(4)(4)% and 36(5)(4)% respectively in the MS[over ¯] (modified minimal substraction) scheme at μ=2  GeV. Read More

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November 2018

Understanding the Air-Exposure Degradation Chemistry at Nanoscale of Layered Oxide Cathodes for Sodium-Ion Batteries.

Nano Lett 2018 Dec 5. Epub 2018 Dec 5.

Undesired reactions between layered sodium transition-metal oxide cathodes and air impede their utilization in practical sodium-ion batteries. Consequently, a fundamental understanding of how layered oxide cathodes degrade in air is of paramount importance, but it has not been fully understood yet. Here a comprehensive study on a model material NaNi0. Read More

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December 2018
2 Reads

Amorphous Quantum Nanomaterials.

Adv Mater 2018 Dec 5:e1806993. Epub 2018 Dec 5.

Department of Materials Science and Engineering, Cornell University, Ithaca, NY, 14853, USA.

In quantum materials, macroscopic behavior is governed in nontrivial ways by quantum phenomena. This is usually achieved by exquisite control over atomic positions in crystalline solids. Here, it is demonstrated that the use of disordered glassy materials provides unique opportunities to tailor quantum material properties. Read More

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December 2018
2 Reads

The Modification of In Situ SiOx Chitosan Coatings by ZnO/TiO NPs and Its Preservation Properties to Silver Carp Fish Balls.

J Food Sci 2018 Dec 5. Epub 2018 Dec 5.

College of Food Science and Engineering, Bohai Univ., Jinzhou, Liaoning, 121013, China.

The composite chitosan coatings were prepared and characterized to evaluate their preservation properties for silver carp fish balls, and the microstructures and physicochemical properties of the coatings were improved by in situ nano silicon oxide (SiOx) and zinc oxide/titania (ZnO/TiO ) nano-particles (NPs). In the chitosan coatings, when the chitosan combines with NPs by chemical bonds, the crystal lattice is slightly changed due to the modification of NPs. The chitosan coatings modified by NPs showed few cracks, among which sodium hexametaphosphate (SHMP) modified ZnO/TiO /SiOx-chitosan (ZTS-CS) coating is proved to be the optimal one. Read More

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December 2018

Comparison of computationally cheap methods for providing insight into the crystal packing of highly bromomethylated azobenzenes.

Acta Crystallogr C Struct Chem 2018 Dec 21;74(Pt 12):1692-1702. Epub 2018 Nov 21.

Department of Chemistry, University of the Free State, PO Box 339, Bloemfontein, Free State, 9300, South Africa.

For five bromomethylated azobenzenes, namely (E)-[4-(bromomethyl)phenyl][4-(dibromomethyl)phenyl]diazene, CHBrN, (E)-1,2-bis[4-(dibromomethyl)phenyl]diazene, CHBrN, (E)-[3-(bromomethyl)phenyl][3-(dibromomethyl)phenyl]diazene, CHBrN, (E)-[3-(dibromomethyl)phenyl][3-(tribromomethyl)phenyl]diazene, CHBrN, and (E)-1,2-bis[3-(dibromomethyl)phenyl]diazene, CHBrN, the computationally cheap CLP PIXEL approach and CrystalExplorer were used for calculating lattice energies and performing Hirshfeld surface analysis via the enrichment ratios of atomic contacts. The procedures and caveats are discussed in detail. The findings from these tools are contrasted with the results of geometric analysis of the structures. Read More

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December 2018

Half-metallicity in uranium intermetallics: crystal structure prediction of a high-pressure phase of UCo.

J Phys Condens Matter 2019 Jan 5;31(2):025501. Epub 2018 Dec 5.

Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany.

Evolutionary crystal structure prediction methods combined with density functional theory (DFT) calculations reveal a high-pressure (hp) phase of the intermetallic compound UCo crystalizing in the NaTl structure type ([Formula: see text]). We predict this compound to be formed at pressures below 9 GPa. Hp-UCo shows the same structural trends as the two experimentally known pseudo-binary compounds UCoRh and UNiPt. Read More

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January 2019

Toward F magnetic resonance thermometry: spin-lattice and spin-spin-relaxation times and temperature dependence of fluorinated drugs at 9.4 T.

MAGMA 2018 Dec 4. Epub 2018 Dec 4.

Berlin Ultrahigh Field Facility (B.U.F.F.), Max Delbrueck Center for Molecular Medicine in the Helmholtz Association, Robert Roessle Straße 10, 13125, Berlin, Germany.

Objective: This study examines the influence of the environmental factor temperature on the F NMR characteristics of fluorinated compounds in phantom studies and in tissue.

Materials And Methods: F MR mapping and MR spectroscopy techniques were used to characterize the F NMR characteristics of perfluoro-crown ether (PFCE), isoflurane, teriflunomide, and flupentixol. T and T mapping were performed, while temperature in the samples was changed (T = 20-60 °C) and monitored using fiber optic measurements. Read More

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December 2018

Evidence for solitonic spin excitations from a charge-lattice-coupled ferroelectric order.

Sci Adv 2018 Nov 30;4(11):eaau7725. Epub 2018 Nov 30.

Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.

Topological defects have been explored in different fields ranging from condensed matter physics and particle physics to cosmology. In condensed matter, strong coupling between charge, spin, and lattice degrees of freedom brings about emergent excitations with topological characteristics at low energies. One-dimensional (1D) systems with degenerate dimerization patterns are typical stages for the generation of topological defects, dubbed "solitons"; for instance, charged solitons are responsible for high electrical conductivity in doped -polyacetylene. Read More

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November 2018
3 Reads

Negative Thermal Expansion Near the Precipice of Structural Stability in Open Perovskites.

Front Chem 2018 20;6:545. Epub 2018 Nov 20.

Department of Physics, University of Connecticut, Storrs, CT, United States.

Negative thermal expansion (NTE) describes the anomalous propensity of materials to shrink when heated. Since its discovery, the NTE effect has been found in a wide variety of materials with an array of magnetic, electronic and structural properties. In some cases, the NTE originates from phase competition arising from the electronic or magnetic degrees of freedom but we here focus on a particular class of NTE which originates from intrinsic dynamical origins related to the lattice degrees of freedom, a property we term negative thermal expansion (SNTE). Read More

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November 2018
3 Reads

A Wide Magnetic Thermal Memory Effect (~55 K) Above Room Temperature Coupled to a Structure Phase Transition of Lattice Symmetry Reduction in High-Temperature Phase in an S = ½ Spin Chain Molecule Crystal.

J Phys Chem B 2018 Dec 5. Epub 2018 Dec 5.

One-dimensional (1D) S = ½ Heisenberg antiferromagnetic (AFM) chain system shows frequently a spin-Peierls-type transition owing to strong spin-lattice coupling. From high-temperature phase (HTP) to low-temperature phase (LTP), the spin chain distortion occurs to lead to the reduction of lattice symmetry in LTP, so-called symmetry breaking (SB) phase transition. Herein, we report the first example that a 1D S = ½ AFM molecular crystal, [Et3(n-Pr)N][Ni(dmit)2] (Et3(n-Pr)N+ = triethylpropylammonium, dmit2- = 2-thioxo-1, 3-dithiole-4,5-dithiolate), shows a structural phase transition with lattice symmetry increase in LTP, which is contrary to the SB phase transition. Read More

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December 2018
1 Read

A Study of the Effects of Hf and Sn on the Microstructure, Hardness and Oxidation of Nb-18Si Silicide Based Alloys without Ti Addition.

Materials (Basel) 2018 Dec 3;11(12). Epub 2018 Dec 3.

Department of Materials Science and Engineering, Sir Robert Hadfield Building, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK.

The paper presents the results of an experimental study of large (≈0.6 kg) arc melted buttons of four Ti free Nb-silicide based alloys with Sn addition with nominal compositions (at.%) Nb-18Si-5Hf-5Sn (EZ1), Nb-18Si-5Al-5Sn (EZ7), Nb-18Si-5Cr-5Hf-5Sn (EZ3) and Nb-18Si-5Al-5Hf-5Sn (EZ4). Read More

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December 2018

Ionic Transportation and Dielectric Properties of YF₃:Eu Nanocrystals.

Nanomaterials (Basel) 2018 Dec 1;8(12). Epub 2018 Dec 1.

State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, China.

The ionic transportation and dielectric properties of YF₃:Eu nanocrystals are investigated by AC impedance spectroscopy. The ion diffusion coefficient and conductivity increase along with the doping concentration and reach their highest values at 4% of Eu. The difference of ionic radius between Eu and Y leads to the structural disorder and lattice strain, which deduces the increase of the ion diffusion coefficient and conductivity before 4% Eu doping; then the interaction of the neighboring doping ions is dominated, which results in the difficulty of ion migration and decreases of the ion diffusion coefficient and conductivity. Read More

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December 2018

A Charge-Transfer Salt Based on Ferrocene/Ferrocenium Pairs and Keggin-Type Polyoxometalates.

Molecules 2018 Nov 30;23(12). Epub 2018 Nov 30.

Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, P.O. Box 644, 48080 Bilbao, Spain.

A new hybrid inorganic-organometallic salt has been obtained from the reaction of the Keggin-type silicotungstate anion with ferrocene in a water/methanol mixture as a result of the partial oxidation of ferrocene molecules to ferrocenium cations. Single-crystal X-ray diffraction analysis reveals the presence of four ferrocenium (Fe) cations and one ferrocene (Fe) molecule per plenary Keggin anion in the crystal structure of [Fe (Cp)₂]₄[SiWO]·[Fe(Cp)₂]·2CH₃OH (). Compound thus constitutes the first example in the literature in which ferrocenium and ferrocene species coexist in the structure of a polyoxometalate-based salt. Read More

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November 2018

Corrosion of Hydrogen Storage Metal Alloy LaMm-NiAlMnCo in the Aqueous Solutions of Alkali Metal Hydroxides.

Materials (Basel) 2018 Nov 30;11(12). Epub 2018 Nov 30.

Faculty of Chemistry, University of Warsaw, ul. Pasteura 1, 02-093 Warsaw, Poland.

Corrosion of pristine AB₅-type metal alloy LaMm-NiAlMnCo in the aqueous solutions of alkali metal hydroxides of diverse composition and concentration was tested. Correlation was observed between the alloy corrosion intensity in various hydroxide solutions, and its electrochemical capacity in these electrolytes. Mm(OH)₃, CoO(OH), and nickel metal aggregates were detected among the products of selective oxidation of the alloy. Read More

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November 2018

Visible-light degradation of sulfonamides by Z-scheme ZnO/g-CN heterojunctions with amorphous FeO as electron mediator.

J Colloid Interface Sci 2018 Nov 27;538:256-266. Epub 2018 Nov 27.

Research Center Jülich, ZEA-3, Jülich 52425, Germany.

ZnO grafted amorphous FeO matrix (ZnO/FeO) was coupled with g-CN to synthesize heterojunction photocatalysts with a loosened multilayered structure. The ZnO/FeO/g-CN exhibited enhanced photocatalytic performance in the degradation of sulfamethazine under visible-light irradiation (λ > 420 nm), with an optimum photocatalytic degradation rate approximately 3.0, 2. Read More

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November 2018

Reducing t noise through rapid scanning.

J Magn Reson 2018 Nov 26;298:31-34. Epub 2018 Nov 26.

US DOE, Ames Laboratory, Ames, IA 50011, USA; Department of Chemistry, Iowa State University, Ames, IA 50011, USA. Electronic address:

The so-called t noise, which arises due to random instabilities in the spectrometer hardware, remains the primary source of noise that limits the sensitivity of most 2D NMR experiments, particularly in the expanding group of solid-state NMR methods that utilize dipolar-recoupling. In this communication we revisit the relationship between the signal intensity and the t noise produced. It is shown that since the latter scales linearly with the signal strength, the use of a conventional relaxation delay of 1. Read More

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November 2018
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Single-Atom Catalysis toward Efficient CO Conversion to CO and Formate Products.

Acc Chem Res 2018 Dec 4. Epub 2018 Dec 4.

State Key Laboratory of Catalysis , Dalian Institute of Chemical Physics, Chinese Academy of Sciences , Dalian 116023 , P. R. China.

Simply yet powerfully, single-atom catalysts (SACs) with atomically dispersed metal active centers on supports have received a growing interest in a wide range of catalytic reactions. As a specific example, SACs have exhibited distinctive performances in CO chemical conversions. The unique structures of SACs are appealing for adsorptive activation of CO molecules, transfer of intermediates from support to active metal sites, and production of desirable products in CO conversion. Read More

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December 2018
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Influence of complex driving motion on propulsion performance of a heaving flexible foil.

Bioinspir Biomim 2018 Dec 4;14(1):016011. Epub 2018 Dec 4.

Department of Mechanical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, People's Republic of China.

This study explores the effects of complex driving motion on the propulsion performance of a flexible foil heaving in the flight regimes of natural flyers. Such a fluid-structure interaction problem is numerically studied using an immersed boundary lattice Boltzmann method (IBLBM) based numerical framework. It is found that, at the Reynolds number 200 and when the foil's bending stiffness and mass ratio are moderate, adding an extra driving motion of doubled frequency to a purely harmonic motion on the foil's leading edge can enhance the thrust and propulsive efficiency by about 860% and 70%, respectively. Read More

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December 2018
3 Reads

An unprecedented pentanary chalcohalide with Mn atoms in two chemical environments: unique bonding characteristics and magnetic properties.

Chem Commun (Camb) 2018 Dec 4. Epub 2018 Dec 4.

State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002, P. R. China.

Mixed-anion chalcohalides have attracted significant attention lately, attributable to their unique structure compositions and captivating physicochemical properties. Herein, an unprecedented pentanary chalcohalide, Cs2[Mn2Ga3S7Cl] (1), was discovered by solid-state reaction at 1223 K. It is constructed by alternately stacked layers, each of which is made by a 2D [Ga3S9]9- ribbon embedded with 1D [Mn2S8Cl]13- chains. Read More

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December 2018
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Highly responsive nature of porous coordination polymer surfaces imaged by in situ atomic force microscopy.

Nat Chem 2018 Dec 3. Epub 2018 Dec 3.

Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University Institute for Advanced Study (KUIAS), Kyoto University, Kyoto, Japan.

The ability of porous coordination polymers to undergo reversible structural transformations in response to the presence of guest molecules has been intensively investigated for applications such as molecular separation, storage, sensing and signalling processes. Here we report on the direct observation of the highly guest-responsive nature of the surface of a single-crystalline porous coordination polymer, which consists of paddlewheel zinc clusters and two types of ligand, by in situ liquid-phase atomic force microscopy. Observations were carried out in solution at constant temperature (28 °C) by high-speed atomic force microscopy with lattice resolution. Read More

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December 2018
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Phosphorylation cascade regulates the formation and maturation of rotaviral replication factories.

Proc Natl Acad Sci U S A 2018 Dec 3. Epub 2018 Dec 3.

Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030;

The rotavirus (RV) genome is replicated and packaged into virus progeny in cytoplasmic inclusions called viroplasms, which require interactions between RV nonstructural proteins NSP2 and NSP5. How viroplasms form remains unknown. We previously found two forms of NSP2 in RV-infected cells: a cytoplasmically dispersed dNSP2, which interacts with hypophosphorylated NSP5; and a viroplasm-specific vNSP2, which interacts with hyperphosphorylated NSP5. Read More

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December 2018
2 Reads