SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Facet

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The CO-assisted thermal decomposition of a new, surfactant-ligated Pt precursor, [Pt(acac)(NHR)](n) (n = 2, 3; R = C(18)H(37)), gives structurally uniform five-fold twinned Pt nanorods. The Pt nanorods, mostly covered by {100} facets, exhibit much enhanced electrocatalytic activity over {100} faceted Pt nanocubes, indicating the superior catalytic performance due to the presence of the reactive twinning interface.

Concepts: Chemical decomposition, Facet

28

One key for the successful integration of implants into the human body is the control of protein adsorption by adjusting surface properties at different length scales. This is particularly important for titanium oxide constituting one of the most common biomedical interfaces. As for titania (TiO(2)) the interface is largely defined by its crystal surface structure it is crucial to understand how the surface crystallinity affects the structure, properties and function of protein layers mediating the subsequent biological reaction. For rutile TiO(2) we demonstrate that the conformation and relative amount of human plasma fibrinogen (HPF) and the structure of adsorbed HPF layers depend on the crystal surface nanostructure by employing thermally etched multi-faceted TiO(2) surfaces. Thermal etching of polycrystalline TiO(2) facilitates a nanoscale crystal faceting and, thus, the creation of different surface nanostructures on a single specimen surface. Atomic force microscopy shows that HPF arranges into networks and thin globular layers on flat and irregular crystal grain surfaces, respectively. On a third, faceted category we observed an alternating conformation of HPF on neighboring facets. The bulk grain orientation obtained from electron back scatter diffraction and thermodynamic mechanisms of surface reconstruction during thermal etching suggest the grain and facet surface specific arrangement and relative amount of adsorbed proteins to depend on the associated on-site free crystal surface energy. Implications for potentially favorable TiO(2) crystal facets regarding the inflammatory response and hemostasis are discussed in view of an advanced surface design of future implants.

Concepts: Protein, Fibrin, Adsorption, Titanium dioxide, C-reactive protein, Nanostructure, Facet, Sculptured thin film

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Watch your figure: Three different shapes of TiO2 nanoparticles with various exposed facets have been synthesized by changing the adsorbents. The spindly octahedron with exposed high-index {401} facet exhibit the highest electrochemical performance than that of the other shapes.

Concepts: Titanium dioxide, Diamond, Rechargeable battery, Lithium-ion battery, Lithium-ion polymer battery, Octahedron, Lithium-ion batteries, Facet

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Surfactants with preferential adsorption to certain crystal facets have been widely employed to manipulate morphologies of colloidal nanocrystals, while mechanisms regarding the origin of facet selectivity remain an enigma. Similar questions exist in biomimetic syntheses concerning biomolecular recognition to materials and crystal surfaces. Here we present mechanistic studies on the molecular origin of the recognition towards platinum {111} facet. By manipulating the conformations and chemical compositions of a platinum {111} facet specific peptide, phenylalanine is identified as the dominant motif to differentiate {111} from other facets. The discovered recognition motif is extended to convert non-specific peptides into {111} specific peptides. Further extension of this mechanism allows the rational design of small organic molecules that demonstrate preferential adsorption to the {111} facets of both platinum and rhodium nanocrystals. This work represents an advance in understanding the organic-inorganic interfacial interactions in colloidal systems and paves the way to rational and predictable nanostructure modulations for many applications.

Concepts: DNA, Protein, Matter, Molecule, Chemistry, Chemical substance, Organic chemistry, Facet

1

This study aimed to extend our theoretical understanding of how mindfulness-based interventions exert their positive influence on measures of occupational health. Employing a randomized waitlist control study design, we sought to (a) assess an Internet-based instructor-led mindfulness intervention for its effect on key factors associated with “recovery from work,” specifically, work-related rumination, fatigue, and sleep quality; (b) assess different facets of mindfulness (acting with awareness, describing, nonjudging, and nonreacting) as mechanisms of change; and © assess whether the effect of the intervention was maintained over time by following up our participants after 3 and 6 months. Participants who completed the mindfulness intervention (n = 60) reported significantly lower levels of work-related rumination and fatigue, and significantly higher levels of sleep quality, when compared with waitlist control participants (n = 58). Effects of the intervention were maintained at 3- and 6-month follow-up with medium to large effect sizes. The effect of the intervention was primarily explained by increased levels of only 1 facet of mindfulness (acting with awareness). This study provides support for online mindfulness interventions to aid recovery from work and furthers our understanding with regard to how mindfulness interventions exert their positive effects. (PsycINFO Database Record

Concepts: Scientific method, Understanding, Medical statistics, Effect, Effects unit, Effect size, Intervention, Facet

0

Hybrid plasmonic nanolasers are intensively studied due to their nanoscale mode confinement and potentials in highly integrated photonic and quantum devices. Till now, the characteristics of plasmonic nanolasers are mostly determined by the crystal facets of top semiconductors such as ZnO nanowires or nanoplates. As a result, the spasers are isolated, and their lasing wavelengths are random and hard to be tuned. Herein we experimentally demonstrate the formation of lead halide perovskites (MAPbX3) based hybrid plasmonic nanolasers and nanolaser array with arbitrary cavity shapes and controllable lasing wavelengths. These spasers are composed of MAPbX3 perovskite nanosheets, which are separated from Au patterns with a 10 nm SiO2 spacer. In contrast to previous reports, here the spasers are determined by the boundary of Au patterns instead of the crystal facets of MAPbX3 nanosheets. As a result, whispering-gallery-mode based circular spaser and spaser array have been successfully realized by patterning the Au substrate into circles and gratings, respectively. The standard wavelength deviation of spaser array is as small as 0.3 nm. Meanwhile, owing to the anion-exchangeable property of MAPbX3 perovskite, the emission wavelengths of spasers have been tuned more than 100 nm back and forth by changing the stoichiometry of perovskite post-synthetically.

Concepts: Quantum mechanics, Light, Wavelength, Pattern, Perovskite, Visible spectrum, Nanoelectronics, Facet

0

Researchers conceptualize grit as the combination of two facets: perseverance of effort and consistency of interests toward long-term goals. We tested the reliability of grit facet scores across the globe and examined how differently each grit facet related to well-being and personality strengths.

Concepts: Scientific method, Energy, Goal, Facet

0

Synthesis protocols for anisotropic CuInX2 (X= S, Se, Te)-based heteronanocrystals (HNCs) are scarce due to the difficulty in balancing the reactivities of multiple precursors and the high solid-state diffusion rates of the cations involved in the CuInX2 lattice. In this work, we report a multi-step seeded growth synthesis protocol that yields colloidal wurtzite CuInS2/ZnS dot core/ rod shell HNCs with photoluminescence in the NIR (~800 nm). The wurtzite CuInS2 NCs used as seeds are obtained by topotactic partial Cu+ for In3+ cation exchange in template Cu2-xS NCs. The seed NCs are injected in a hot solution of zinc oleate and hexadecylamine in octadecene, 20 s after the injection of sulfur in octadecene. This results in heteroepitaxial growth of wurtzite ZnS primarily on the Sulfur-terminated polar facet of the CuInS2 seed NCs, the other facets being overcoated only by a thin (1 monolayer) shell. The fast (21 nm/min) asymmetric axial growth of the nanorod proceeds by addition of [ZnS] monomer units, so that the polarity of the terminal (002) facet is preserved throughout the growth. The delayed injection of the CuInS2 seed NCs is crucial to allow the concentration of [ZnS] monomers to build up, thereby maximizing the anisotropic heteroepitaxial growth rates while minimizing the rates of competing processes (etching, cation exchange, alloying). Nevertheless, a mild etching still occurred, likely prior to the onset of heteroepitaxial overgrowth, shrinking the core size from 5.5 to 4 nm. The insights provided by this work open up new possibilities in designing multi-functional Cu-chalcogenide based colloidal heteronanocrystals.

Concepts: Polymer, Zinc, Monomer, Seed, The Onset, Sphalerite, Cation exchange capacity, Facet

0

Most community question answering (CQA) websites manage plenty of question-answer pairs (QAPs) through topic-based organizations, which may not satisfy users' fine-grained search demands. Facets of topics serve as a powerful tool to navigate, refine, and group the QAPs. In this work, we propose FACM, a model to annotate QAPs with facets by extending convolution neural networks (CNNs) with a matching strategy. First, phrase information is incorporated into text representation by CNNs with different kernel sizes. Then, through a matching strategy among QAPs and facet label texts (FaLTs) acquired from Wikipedia, we generate similarity matrices to deal with the facet heterogeneity. Finally, a three-channel CNN is trained for facet label assignment of QAPs. Experiments on three real-world data sets show that FACM outperforms the state-of-the-art methods.

Concepts: Annotation, Neural network, Text messaging, Annotated bibliography, Facet, Assignment problem, Representation, TEXT

0

It has been reported that photogenerated electrons and holes can be directed toward specific crystal facets of a semiconductor particle, which is believed to arise from differences in their surface electronic structures, suggesting that different facets can act as either photo-reduction or photo-oxidation sites. This study examines the propensity for this effect to occur in faceted, plate-like bismuth molybdate (Bi2MoO6), which is a useful photocatalyst for water oxidation. Photo-excited electrons and holes are shown to be spatially separated toward the {100} and {001}/{010} facets of Bi2MoO6, respectively, by facet-dependent photo-deposition of noble metals (Pt, Au and Ag) and metal oxides (PbO2, MnOx and CoOx). Theoretical calculations revealed that differences in energy levels between the conduction bands and valence bands of the {100} and {001}/{010} facets can contribute to electrons and holes being drawn to different surfaces of the plate-like Bi2MoO6. Utilizing this knowledge, the photo-oxidative capability of Bi2MoO6 was improved by adding an efficient water oxidation co-catalyst, CoOx, to the system whereby the extent of enhancement was shown to be governed by co-catalyst location. Greater oxygen evolution occurred when CoOx was selectively deposited on the hole-rich {001}/{010} facets of Bi2MoO6 compared to when the CoOx was randomly located across all facets. The elevated performance exhibited for the selectively loaded CoOx/Bi2MoO6 was ascribed to the greater opportunity for hole trapping by the co-catalyst being accentuated over other potentially detrimental effects such as the co-catalyst acting as a recombination medium and/or covering reactive sites. The results indicate that harnessing the synergy between spatial charge separation and co-catalyst location on the appropriate facets of plate-like Bi2MoO6 can promote its photocatalytic activity.

Concepts: Oxygen, Hydrogen, Atom, Oxide, Semiconductor, Photocatalysis, Electronic band structure, Facet