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Find video protocols related to scientific articles indexed in Pubmed.
Surface-step-induced oscillatory oxide growth.
Phys. Rev. Lett.
PUBLISHED: 09-25-2014
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We report in situ atomic-resolution transmission electron microscopy observations of the oxidation of stepped Cu surfaces. We find that the presence of surface steps both inhibits oxide film growth and leads to the oxide decomposition, thereby resulting in oscillatory oxide film growth. Using atomistic simulations, we show that the oscillatory oxide film growth is induced by oxygen adsorption on the lower terrace along the step edge, which destabilizes the oxide film formed on the upper terrace.
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High-resolution spectroscopy of bonding in a novel BeP2N4 compound.
Microsc. Microanal.
PUBLISHED: 04-03-2014
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The recently discovered compound BeP2N4 that crystallizes in the phenakite-type structure has potential application as a high strength optoelectronic material. Therefore, it is important to analyze experimentally the electronic structure, which was done in the present work by monochromated electron energy-loss spectroscopy. The detection of Be is challenging due to its low atomic number and easy removal under electron bombardment. We were able to determine the bonding behavior and coordination of the individual atomic species including Be. This is evident from a good agreement between experimental electron energy-loss near-edge structures of the Be-K-, P-L2,3-, and N-K-edges and density functional theory calculations.
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Direct observation of a long-lived single-atom catalyst chiseling atomic structures in graphene.
Nano Lett.
PUBLISHED: 02-03-2014
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Fabricating stable functional devices at the atomic scale is an ultimate goal of nanotechnology. In biological processes, such high-precision operations are accomplished by enzymes. A counterpart molecular catalyst that binds to a solid-state substrate would be highly desirable. Here, we report the direct observation of single Si adatoms catalyzing the dissociation of carbon atoms from graphene in an aberration-corrected high-resolution transmission electron microscope (HRTEM). The single Si atom provides a catalytic wedge for energetic electrons to chisel off the graphene lattice, atom by atom, while the Si atom itself is not consumed. The products of the chiseling process are atomic-scale features including graphene pores and clean edges. Our experimental observations and first-principles calculations demonstrated the dynamics, stability, and selectivity of such a single-atom chisel, which opens up the possibility of fabricating certain stable molecular devices by precise modification of materials at the atomic scale.
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Subnanometer vacancy defects introduced on graphene by oxygen gas.
J. Am. Chem. Soc.
PUBLISHED: 01-30-2014
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The basal plane of graphene has been known to be less reactive than the edges, but some studies observed vacancies in the basal plane after reaction with oxygen gas. Observation of these vacancies has typically been limited to nanometer-scale resolution using microscopic techniques. This work demonstrates the introduction and observation of subnanometer vacancies in the basal plane of graphene by heat treatment in a flow of oxygen gas at low temperature such as 533 K or lower. High-resolution transmission electron microscopy was used to directly observe vacancy structures, which were compared with image simulations. These proposed structures contain C?O, pyran-like ether, and lactone-like groups.
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Electroreduction of carbon monoxide to liquid fuel on oxide-derived nanocrystalline copper.
Nature
PUBLISHED: 01-27-2014
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The electrochemical conversion of CO2 and H2O into liquid fuel is ideal for high-density renewable energy storage and could provide an incentive for CO2 capture. However, efficient electrocatalysts for reducing CO2 and its derivatives into a desirable fuel are not available at present. Although many catalysts can reduce CO2 to carbon monoxide (CO), liquid fuel synthesis requires that CO is reduced further, using H2O as a H(+) source. Copper (Cu) is the only known material with an appreciable CO electroreduction activity, but in bulk form its efficiency and selectivity for liquid fuel are far too low for practical use. In particular, H2O reduction to H2 outcompetes CO reduction on Cu electrodes unless extreme overpotentials are applied, at which point gaseous hydrocarbons are the major CO reduction products. Here we show that nanocrystalline Cu prepared from Cu2O ('oxide-derived Cu') produces multi-carbon oxygenates (ethanol, acetate and n-propanol) with up to 57% Faraday efficiency at modest potentials (-0.25?volts to -0.5?volts versus the reversible hydrogen electrode) in CO-saturated alkaline H2O. By comparison, when prepared by traditional vapour condensation, Cu nanoparticles with an average crystallite size similar to that of oxide-derived copper produce nearly exclusive H2 (96% Faraday efficiency) under identical conditions. Our results demonstrate the ability to change the intrinsic catalytic properties of Cu for this notoriously difficult reaction by growing interconnected nanocrystallites from the constrained environment of an oxide lattice. The selectivity for oxygenates, with ethanol as the major product, demonstrates the feasibility of a two-step conversion of CO2 to liquid fuel that could be powered by renewable electricity.
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Crystalline fibers of metal-Peptide double ladders.
Inorg Chem
PUBLISHED: 11-20-2013
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Despite remarkable progress in the field of MOFs, structures based on long-flexible organic linkers are scarce and the majority of such materials rely on rigid linkers. In this work, crystals of a new metal-organic double ladder (MODL) are obtained by linking a pentapeptide (NH2-Glu-pCO2Phe-pCO2Phe-Ala-Gly-OH) with cadmium acetate to produce a Cd(2-pyrrolidone-pCO2Phe-pCO2Phe-Ala-Gly)(H2O)3 framework. SEM and TEM analyses show the fibrous nature of the crystals and show that the infinite cadmium oxide rod secondary building units (SBUs) are aligned with the longitudinal axis of the nanofibers.
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In situ atomic-scale visualization of oxide islanding during oxidation of Cu surfaces.
Chem. Commun. (Camb.)
PUBLISHED: 10-16-2013
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Oxidation of Cu occurs via Cu2O islanding on an oxide wetting layer at a critical thickness of two atomic layers. The transition from 2D wetting-layer growth to 3D oxide islanding is driven energetically arising from the Cu-Cu2O interfacial interaction.
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Atomic resolution imaging of grain boundary defects in monolayer chemical vapor deposition-grown hexagonal boron nitride.
J. Am. Chem. Soc.
PUBLISHED: 04-30-2013
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Grain boundaries are observed and characterized in chemical vapor deposition-grown sheets of hexagonal boron nitride (h-BN) via ultra-high-resolution transmission electron microscopy at elevated temperature. Five- and seven-fold defects are readily observed along the grain boundary. Dynamics of strained regions and grain boundary defects are resolved. The defect structures and the resulting out-of-plane warping are consistent with recent theoretical model predictions for grain boundaries in h-BN.
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Step-edge-induced oxide growth during the oxidation of Cu surfaces.
Phys. Rev. Lett.
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Using in situ atomic-resolution electron microscopy observations, we report observations of the oxide growth during the oxidation of stepped Cu surfaces. Oxidation occurs via direct growth of Cu(2)O on flat terraces with Cu adatoms detaching from steps and diffusing across the terraces. This process involves neither reconstructive oxygen adsorption nor oxygen subsurface incorporation and is rather different from the mechanism of solid-solid transformation of bulk oxidation that is most commonly postulated. These results demonstrate that the presence of surface steps can promote the development of a flat metal-oxide interface by kinetically suppressing subsurface oxide formation at the metal-oxide interface.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.