251 research outputs found
Rocking motion induced charging of C60 on h-BN/Ni(111)
One monolayer of C60 on one monolayer of hexagonal boron nitride on nickel is
investigated by photoemission. Between 150 and 250 K the work function
decreases and the binding energy of the highest occupied molecular orbital
(HOMO) increases by approx. 100 meV. In parallel, the occupancy of the, in the
cold state almost empty, lowest unoccupied molecular orbital (LUMO) changes by
0.4 electrons. This charge redistribution is triggered by onset of molecular
rocking motion, i.e. by orientation dependent tunneling between the LUMO of C60
and the substrate. The magnitude of the charge transfer is large and cannot be
explained within a single particle picture. It is proposed to involve
electron-phonon coupling where C60- polaron formation leads to electron
self-trapping.Comment: 15 pages, 4 figure
Errors in device localization in MRI using Z-frames.
The use of a passive MRI-visible tracking frame is a common method of localizing devices in MRI space for MRI-guided procedures. One of the most common tracking frame designs found in the literature is the z-frame, as it allows six degree-of-freedom pose estimation using only a single image slice. Despite the popularity of this design, it is susceptible to errors in pose estimation due to various image distortion mechanisms in MRI. In this paper, the absolute error in using a z-frame to localize a tool in MRI is quantified over various positions of the z-frame relative to the MRI isocenter, and for various levels of static magnetic field inhomogeneity. It was found that the error increases rapidly with distance from the isocenter in both the horizontal and vertical directions, but the error is much less sensitive to position when multiple contiguous slices are used with slice-select gradient nonlinearity correction enabled, as opposed to the more common approach of only using a single image slice. In addition, the error is found to increase rapidly with an increasing level of static field inhomogeneity, even with the z-frame placed within 10 cm of the isocenter
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Low-Temperature Growth of Carbon Nanotube Forests Consisting of Tubes with Narrow Inner Spacing Using Co/Al/Mo Catalyst on Conductive Supports.
We grow dense carbon nanotube forests at 450 °C on Cu support using Co/Al/Mo multilayer catalyst. As a partial barrier layer for the diffusion of Co into Mo, we apply very thin Al layer with the nominal thickness of 0.50 nm between Co and Mo. This Al layer plays an important role in the growth of dense CNT forests, partially preventing the Co-Mo interaction. The forests have an average height of ∼300 nm and a mass density of 1.2 g cm(-3) with tubes exhibiting extremely narrow inner spacing. An ohmic behavior is confirmed between the forest and Cu support with the lowest resistance of ∼8 kΩ. The forest shows a high thermal effusivity of 1840 J s(-0.5) m(-2) K(-1), and a thermal conductivity of 4.0 J s(-1) m(-1) K(-1), suggesting that these forests are useful for heat dissipation devices.This work has been funded by the European projects Technotubes and Grafol. H.S. acknowledges a research fellowship from the Japanese Society for the Promotion of Science (JSPS).This is the accepted manuscript. The final version is available at http://pubs.acs.org/doi/abs/10.1021/acsami.5b04846
EXPOSURE TIME OF ORAL RABIES VACCINE BAITS RELATIVE TO BAITING DENSITY AND RACCOON POPULATION DENSITY
Oral rabies vaccination (ORV) baiting programs for control of raccoon (Procyon lotor) rabies in the USA have been conducted or are in progress in eight states east of the Mississippi River. However, data specific to the relationship between raccoon population density and the minimum density of baits necessary to significantly elevate rabies immunity are few. We used the 22-km2 US National Aeronautics and Space Administration Plum Brook Station (PBS) in Erie County, Ohio, USA, to evaluate the period of exposure for placebo vaccine baits placed at a density of 75 baits/km2 relative to raccoon population density. Our objectives were to 1) estimate raccoon population density within the fragmented forest, old-field, and industrial landscape at PBS; and 2) quantify the time that placebo, Merial RABORAL V-RG* vaccine baits were available to raccoons. From August through November 2002 we surveyed raccoon use of PBS along 19.3 km of paved-road transects by using a forward-looking infrared camera mounted inside a vehicle. We used Distance 3.5 software to calculate probability of detection function by which we estimated raccoon population density from transect data. Estimated population density on PBS decreased from August (33.4 raccoons/km2) through November (13.6 raccoons/km2), yielding a monthly mean of 24.5 raccoons/km2. We also quantified exposure time for ORV baits placed by hand on five 1-km2 grids on PBS from September through October. An average 82.7% (SD=4.6) of baits were removed within 1 wk of placement. Given raccoon population density, estimates of bait removal and sachet condition, and assuming 22.9% nontarget take, the baiting density of 75/ km\u27 yielded an average of 3.3 baits consumed per raccoon anti the sachet perforated
EXPOSURE TIME OF ORAL RABIES VACCINE BAITS RELATIVE TO BAITING DENSITY AND RACCOON POPULATION DENSITY
Oral rabies vaccination (ORV) baiting programs for control of raccoon (Procyon lotor) rabies in the USA have been conducted or are in progress in eight states east of the Mississippi River. However, data specific to the relationship between raccoon population density and the minimum density of baits necessary to significantly elevate rabies immunity are few. We used the 22-km2 US National Aeronautics and Space Administration Plum Brook Station (PBS) in Erie County, Ohio, USA, to evaluate the period of exposure for placebo vaccine baits placed at a density of 75 baits/km2 relative to raccoon population density. Our objectives were to 1) estimate raccoon population density within the fragmented forest, old-field, and industrial landscape at PBS; and 2) quantify the time that placebo, Merial RABORAL V-RG* vaccine baits were available to raccoons. From August through November 2002 we surveyed raccoon use of PBS along 19.3 km of paved-road transects by using a forward-looking infrared camera mounted inside a vehicle. We used Distance 3.5 software to calculate probability of detection function by which we estimated raccoon population density from transect data. Estimated population density on PBS decreased from August (33.4 raccoons/km2) through November (13.6 raccoons/km2), yielding a monthly mean of 24.5 raccoons/km2. We also quantified exposure time for ORV baits placed by hand on five 1-km2 grids on PBS from September through October. An average 82.7% (SD=4.6) of baits were removed within 1 wk of placement. Given raccoon population density, estimates of bait removal and sachet condition, and assuming 22.9% nontarget take, the baiting density of 75/ km\u27 yielded an average of 3.3 baits consumed per raccoon anti the sachet perforated
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Stability of graphene doping with MoO<inf>3</inf>and I<inf>2</inf>
We dope graphene by evaporation of MoO_3 or by solution-deposition of I_2 and assess the doping stability for its use as transparent electrodes. Electrical measurements show that both dopants increase the graphene sheet conductivity and find that MoO_3-doped graphene is significantly more stable during thermal cycling. Raman spectroscopy finds that neither dopant creates defects in the graphene lattice. In-situ photoemission determines the minimum necessary thickness of MoO_3 for full graphene doping.This is the author's accepted manuscript. Copyright (2014) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Applied Physics Letters (volume 105) and may be found at http://scitation.aip.org/content/aip/journal/apl/105/10/10.1063/1.489502
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Conjugated polyelectrolyte nano field emission adlayers.
Here we report on a straightforward and rapid means of enhancing the field electron emission performance of nascent vertically aligned multi-walled carbon nanotubes by introducing a polar zwitterionic conjugated polyelectrolyte adlayer at the vacuum-emitter interface. We attribute the observed 66% decrease in turn-on electric field to the augmented emitter micro-morphology and shifted surface band structure. The composite emitters can be optically modulated by exploiting the absorption cross-section of the solution cast adlayer, which increases the local carrier concentration which broadens the effective electrostatic shape of the emitter during optical excitation. Assessment via scanning anode field emission microscopy reveals a 25% improvement in DC time stability, a significant reduction in long-term hysteresis shift, and a threefold increase in bandwidth during pulsed mode operation.Oppenheimer TrustThis is the final version of the article. It first appeared from the Royal Society of Chemistry via http://dx.doi.org/10.1039/c6nh00071
Transport in polymer-supported chemically-doped CVD graphene
In this study we report on the electron transport in flexible-transparent polymer supported chemically doped chemical vapour deposited (CVD) graphene.Oppenheimer Resaerch Trus
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Carbon nanotube forests as top electrode in electroacoustic resonators
We grow carbon nanotube forests on piezoelectric AlN films and fabricate and characterize nanotube-based solidly mounted bulk acoustic wave resonators employing the forests as the top electrode material. The devices show values for quality factor at anti-resonance of ∼430, and at resonance of ∼100. The effective coupling coefficient is of ∼6%, and the resonant frequencies are up to ∼800 MHz above those observed with metallic top electrodes. AlN promotes a strong catalyst-support interaction, which reduces Fe catalyst mobility, and thus enforces the growth of forests by the base growth mechanism.This work was partially supported by the European Commission through the project GRAFOL and the COST action IC1208 and by the Ministerio de Economía y Competitividad del Gobierno de España through project MAT2013-45957.This is the accepted manuscript. The final version is available at http://scitation.aip.org/content/aip/journal/apl/107/13/10.1063/1.4932197
Tau protein, A beta 42 and S-100B protein in cerebrospinal fluid of patients with dementia with Lewy bodies
The intra vitam diagnosis of dementia with Lewy bodies (DLB) is still based on clinical grounds. So far no technical investigations have been available to support this diagnosis. As for tau protein and beta-amyloid((1-42)) (Abeta42), promising results for the diagnosis of Alzheimer's disease ( AD) have been reported; we evaluated these markers and S-100B protein in cerebrospinal fluid (CSF), using a set of commercially available assays, of 71 patients with DLB, 67 patients with AD and 41 nondemented controls (NDC) for their differential diagnostic relevance. Patients with DLB showed significantly lower tau protein values compared to AD but with a high overlap of values. More prominent differences were observed in the comparison of DLB patients with all three clinical core features and AD patients. Abeta42 levels were decreased in the DLB and AD groups versus NDC, without significant subgroup differences. S-100B levels were not significantly different between the groups. Tau protein levels in CSF may contribute to the clinical distinction between DLB and AD, but the value of the markers is still limited especially due to mixed pathology. We conclude that more specific markers have to be established for the differentiation of these diseases. Copyright (C) 2005 S. Karger AG, Basel
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