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result(s) for
"Clark, Nick"
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Twilight of the elves
\"In the second book of The Adventurers Guild, Zed and Brock must save the elven city\"-- Provided by publisher.
Book
Tracking single adatoms in liquid in a transmission electron microscope
Single atoms or ions on surfaces affect processes from nucleation
1
to electrochemical reactions
2
and heterogeneous catalysis
3
. Transmission electron microscopy is a leading approach for visualizing single atoms on a variety of substrates
4
,
5
. It conventionally requires high vacuum conditions, but has been developed for in situ imaging in liquid and gaseous environments
6
,
7
with a combined spatial and temporal resolution that is unmatched by any other method—notwithstanding concerns about electron-beam effects on samples. When imaging in liquid using commercial technologies, electron scattering in the windows enclosing the sample and in the liquid generally limits the achievable resolution to a few nanometres
6
,
8
,
9
. Graphene liquid cells, on the other hand, have enabled atomic-resolution imaging of metal nanoparticles in liquids
10
. Here we show that a double graphene liquid cell, consisting of a central molybdenum disulfide monolayer separated by hexagonal boron nitride spacers from the two enclosing graphene windows, makes it possible to monitor, with atomic resolution, the dynamics of platinum adatoms on the monolayer in an aqueous salt solution. By imaging more than 70,000 single adatom adsorption sites, we compare the site preference and dynamic motion of the adatoms in both a fully hydrated and a vacuum state. We find a modified adsorption site distribution and higher diffusivities for the adatoms in the liquid phase compared with those in vacuum. This approach paves the way for in situ liquid-phase imaging of chemical processes with single-atom precision.
The ability to resolve single atoms in a liquid environment is demonstrated by combining a transmission electron microscope and a robust double graphene liquid cell, enabling studies of adatom motion at solid–liquid interfaces.
Journal Article
The origins of happiness : the science of well-being over the life course
\"What makes people happy? Why should governments care about people's well-being? How would policy change if well-being was the main objective? The Origins of Happiness seeks to revolutionize how we think about human priorities and to promote public policy changes that are based on what really matters to people. Drawing on a uniquely comprehensive range of evidence from longitudinal data on over one hundred thousand individuals in Britain, the United States, Australia, and Germany, the authors consider the key factors that affect human well-being. The authors explore factors such as income, education, employment, family conflict, health, childcare, and crime -- and their findings are not what we might expect. Contrary to received wisdom, income inequality accounts for only two percent or less of the variance in happiness across the population; the critical factors affecting a person's happiness are their relationships and their mental and physical health. More people are in misery due to mental illness than to poverty, unemployment, or physical illness. Examining how childhood influences happiness in adulthood, the authors show that academic performance is a less important predictor than emotional health and behavior, which is shaped tremendously by schools, individual teachers, and parents. For policymakers, the authors propose new forms of cost-effectiveness analysis that places well-being at center stage. Groundbreaking in its scope and results, The Origins of Happiness offers all of us a new vision for how we might become more healthy, happy, and whole\"-- Provided by publisher.
Book
Ion exchange in atomically thin clays and micas
The physical properties of clays and micas can be controlled by exchanging ions in the crystal lattice. Atomically thin materials can have superior properties in a range of membrane applications, yet the ion-exchange process itself remains largely unexplored in few-layer crystals. Here we use atomic-resolution scanning transmission electron microscopy to study the dynamics of ion exchange and reveal individual ion binding sites in atomically thin and artificially restacked clays and micas. We find that the ion diffusion coefficient for the interlayer space of atomically thin samples is up to 10
4
times larger than in bulk crystals and approaches its value in free water. Samples where no bulk exchange is expected display fast exchange at restacked interfaces, where the exchanged ions arrange in islands with dimensions controlled by the moiré superlattice dimensions. We attribute the fast ion diffusion to enhanced interlayer expandability resulting from weaker interlayer binding forces in both atomically thin and restacked materials. This work provides atomic scale insights into ion diffusion in highly confined spaces and suggests strategies to design exfoliated clay membranes with enhanced performance.
Layered clays are of interest for membranes and many other applications but their ion-exchange dynamics remain unexplored in atomically thin materials. Here, using electron microscopy, it is found that the ion diffusion for few-layer two-dimensional clays approaches that of free water and that superlattice cation islands can form in twisted and restacked materials.
Journal Article
Superman : American alien
\"Hollywood screenwriter and Eisner Award nominee Max Landis (Chronicle, American Ultra, Adventures of Superman) joins forces with top comics artists including Jock, Francis Manapul and Jae Lee to bring you Superman: American Alien, a new epic that chronicles the life of Clark Kent and his development into the archetypal hero he will eventually become. But these are not the stories of the iconic \"Superman\" as you know him, but of the soft-spoken, charming, often-funny Kansas farm-boy behind the Man of Steel. With the tone of each issue ranging from heartwarming and simple, to frighteningly gritty and violent, to sexy, sun-kissed and funny, Superman: American Alien is unlike anything you've seen before.\"-- Provided by publisher.
Book
Noise2Void for denoising atomic resolution scanning transmission electron microscopy images
The Noise2Void technique is demonstrated for successful denoising of atomic resolution scanning transmission electron microscopy (STEM) images. The technique is applied to denoising atomic resolution images and videos of gold adatoms on a graphene surface within a graphene liquid-cell, with the denoised experimental data qualitatively demonstrating improved visibility of both the Au adatoms and the graphene lattice. The denoising performance is quantified by comparison to similar simulated data and the approach is found to significantly outperform both total variation and simple Gaussian blurring. Compared to other denoising methods, the Noise2Void technique has the combined advantages that it requires no manual intervention during training or denoising, no prior knowledge of the sample and is compatible with real-time data acquisition rates of at least 45 frames per second.
Journal Article
Administration of FTY720 during Tourniquet-Induced Limb Ischemia Reperfusion Injury Attenuates Systemic Inflammation
Acute ischemia-reperfusion injury (IRI) of the extremities leads to local and systemic inflammatory changes which can hinder limb function and can be life threatening. This study examined whether the administration of the T-cell sequestration agent, FTY720, following hind limb tourniquet-induced skeletal muscle IRI in a rat model would attenuate systemic inflammation and multiple end organ injury. Sprague-Dawley rats were subjected to 1 hr of ischemia via application of a rubber band tourniquet. Animals were randomized to receive an intravenous bolus of either vehicle control or FTY720 15 min after band placement. Rats (n=10/time point) were euthanized at 6, 24, and 72 hr post-IRI. Peripheral blood as well as lung, liver, kidney, and ischemic muscle tissue was analyzed and compared between groups. FTY720 treatment markedly decreased the number of peripheral blood T cells (p<0.05) resulting in a decreased systemic inflammatory response and lower serum creatinine levels and had a modest but significant effect in decreasing the transcription of injury-associated target genes in multiple end organs. These findings suggest that early intervention with FTY720 may benefit the treatment of IRI of the limb. Further preclinical studies are necessary to characterize the short-term and long-term beneficial effects of FTY720 following tourniquet-induced IRI.
Journal Article
Analysis of Vascular Development in the hydra Sterol Biosynthetic Mutants of Arabidopsis
The control of vascular tissue development in plants is influenced by diverse hormonal signals, but their interactions during this process are not well understood. Wild-type sterol profiles are essential for growth, tissue patterning and signalling processes in plant development, and are required for regulated vascular patterning.
Here we investigate the roles of sterols in vascular tissue development, through an analysis of the Arabidopsis mutants hydra1 and fackel/hydra2, which are defective in the enzymes sterol isomerase and sterol C-14 reductase respectively. We show that defective vascular patterning in the shoot is associated with ectopic cell divisions. Expression of the auxin-regulated AtHB8 homeobox gene is disrupted in mutant embryos and seedlings, associated with variably incomplete vascular strand formation and duplication of the longitudinal axis. Misexpression of the auxin reporter proIAA2ratioGUS and mislocalization of PIN proteins occurs in the mutants. Introduction of the ethylene-insensitive ein2 mutation partially rescues defective cell division, localization of PIN proteins, and vascular strand development.
The results support a model in which sterols are required for correct auxin and ethylene crosstalk to regulate PIN localization, auxin distribution and AtHB8 expression, necessary for correct vascular development.
Journal Article
Raman Mapping Analysis of Graphene-Integrated Silicon Micro-Ring Resonators
We present a Raman mapping study of monolayer graphene G and 2D bands, after integration on silicon strip-waveguide-based micro-ring resonators (MRRs) to characterize the effects of the graphene transfer processes on its structural and optoelectronic properties. Analysis of the Raman G and 2D peak positions and relative intensities reveal that the graphene is electrically intrinsic where it is suspended over the MRR but is moderately hole-doped where it sits on top of the waveguide structure. This is suggestive of Fermi level ‘pinning’ at the graphene-silicon heterogeneous interface, and we estimate that the Fermi level shifts
down
by approximately 0.2 eV from its intrinsic value, with a corresponding peak hole concentration of ~ 3 × 10
12
cm
−2
. We attribute variations in observed G peak asymmetry to a combination of a ‘stiffening’ of the
E
2g
optical phonon where the graphene is supported by the underlying MRR waveguide structure, as a result of this increased hole concentration, and a lowering of the degeneracy of the same mode as a result of localized out-of-plane ‘wrinkling’ (curvature effect), where the graphene is suspended. Examination of graphene integrated with two different MRR devices, one with radii of curvature
r
= 10 μm and the other with
r
= 20 μm, indicates that the device geometry has no measureable effect on the level of doping.
Journal Article
