1,228 research outputs found
High-temperature-grown buffer layer boosts electron mobility in epitaxial La-doped BaSnO/SrZrO heterostructures
By inserting a SrZrO buffer layer between the film and the substrate, we
demonstrate a significant reduction of the threading dislocation density with
an associated improvement of the electron mobility in La:BaSnO films. A
room temperature mobility of 140 cm V is achieved for
25-nm-thick films without any post-growth treatment. The density of threading
dislocations is only cm for buffered films prepared
on (110) TbScO substrates by pulsed laser deposition.Comment: 5 pages, 4 figure
Adhesion and spreading of cultured endothelial cells on modified and unmodified poly(ethylene terephthalate): a morphological study
The in vitro adhesion and spreading of human endothelial cells (HEC) on hydrophobic poly(ethylene terephthalate) (PETP) and moderately wettable tissue culture polyethylene terephthalate) (TCPETP) were studied with light microscopy and electron microscopy. Numbers of HEC adhering on TCPETP were always higher than those found on PETP. When cells were seeded in the presence of serum, extensive cell spreading on both PETP and TCPETP was observed after the first 30 min. Thereafter, spread cells appeared to withdraw from the PETP surface, resulting in irregularly shaped cells. Complete cell spreading occurred on TCPETP. Complete cell spreading also occurred on PETP and TCPETP when HEC had first been seeded from phosphate buffer solution and serum was supplied after 30 min. Furthermore, HEC spread on both PETP and TCPETP when the surfaces were precoated with protein(s), which promotes cell adhesion. However, when plasma was used for the coating, spread cells did not proliferate in a monolayer pattern. This study shows that TCPETP is, in general, a better surface for adhesion and proliferation of HEC than is PETP, suggesting that vascular prostheses with a TCPETP-like surface will perform better in vivo than prostheses made of PETP
Ruddlesden-Popper faults in LaNiO3/LaAlO3 superlattices
Scanning transmission electron microscopy in combination with electron
energy-loss spectroscopy is used to study LaNiO3/LaAlO3 superlattices grown on
(La,Sr)AlO4 with varying single-layer thicknesses which are known to control
their electronic properties. The microstructure of the films is investigated on
the atomic level and the role of observed defects is discussed in the context
of the different properties. Two types of Ruddlesden-Popper faults are found
which are either two or three dimensional. The common planar Ruddlesden-Popper
fault is induced by steps on the substrate surface. In contrast, the
three-dimensionally arranged Ruddlesden-Popper fault, whose size is in the
nanometer range, is caused by the formation of local stacking faults during
film growth. Furthermore, the interfaces of the superlattices are found to show
different sharpness, but the microstructure does not depend substantially on
the single-layer thickness.Comment: 14 pages, 6 figure
Digital modulation of the nickel valence state in a cuprate-nickelate heterostructure
Layer-by-layer oxide molecular beam epitaxy has been used to synthesize
cuprate-nickelate multilayer structures of composition
(LaCuO)/LaO/(LaNiO). In a combined experimental and
theoretical study, we show that these structures allow a clean separation of
dopant and doped layers. Specifically, the LaO layer separating cuprate and
nickelate blocks provides an additional charge that, according to density
functional theory calculations, is predominantly accommodated in the
interfacial nickelate layers. This is reflected in an elongation of bond
distances and changes in valence state, as observed by scanning transmission
electron microscopy and x-ray absorption spectroscopy. Moreover, the predicted
charge disproportionation in the nickelate interface layers leads to a
thickness-dependent metal-to-insulator transition for , as observed in
electrical transport measurements. The results exemplify the perspectives of
charge transfer in metal-oxide multilayers to induce doping without introducing
chemical and structural disorder
The effect of microstructural scale on hardness of MoSi2-Mo5Si3 eutectics
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/31005/1/0000680.pd
Dissolved aluminium in the ocean conveyor of theWest Atlantic Ocean: Effects of the biological cycle, scavenging, sediment resuspension and hydrography
The concentrations of dissolved aluminium (dissolved Al) were studied along the West Atlantic GEOTRACESGA02 transect from 64°N to 50°S. Concentrations ranged from~0.5 nmol kg-1 in the high latitude surface watersto ~48 nmol kg-1 in surfacewaters around 25°N. Elevated surfacewater concentrations due to atmospheric dustloading have little influence on the deep water distribution. However, just belowthe thermocline, both Northernand Southern Hemisphere Subtropical Mode Waters are elevated in Al, most likely related to atmospheric dustdeposition in the respective source regions.In the deep ocean, high concentrations of up to 35 nmol kg-1 were observed in North Atlantic DeepWater as aresult of Al input via sediment resuspension. Comparatively lowdeepwater concentrationswere associatedwithwater masses of Antarctic origin. During water mass advection, Al loss by scavenging overrules input viaremineralisation and sediment resuspension at the basin wide scale. Nevertheless, sediment resuspension ismore important than previously realised for the deep ocean Al distribution and even more intensive samplingis needed in bottom waters to constrain the spatial heterogeneity in the global deep ocean.This thus far longest (17,500 km) full depth ocean section shows that the distribution of Al can be explained by itsinput sources and the combination of association with particles and release from those particles at depth, thelattermost likelywhen the particles remineralise. The association of Alwith particles can be due to incorporationof Al into biogenic silica or scavenging of Al onto biogenic particles. The interaction between Al and biogenicparticles can lead to the coupled cycling of Al and silicate that is observed in some ocean regions. However, inother regions this coupling is not observed due to (i) advective processes bringing in older water masses thatare depleted in Al, (ii) unfavourable scavenging conditions in the water column, (iii) low surface concentrationsof Al or (iv) additional Al sources, notably sediment resuspension
МНОГОФАЗНО-ОДНОФАЗНыЕ РЕВЕРСИВНыЕ ЭЛЕКТРОМАШИННО-ВЕНТИЛЬНыЕ ПРЕОБРАЗОВАТЕЛИ БЕСКОНТАКТНыХ МАШИН ДВОЙНОГО ПИТАНИЯ
Розглянуто процеси в багатофазно-однофазних реверсивних електромашинно-вентильних перетворю-
вачах безконтактних машин подвійного живлення.
Рассмотрены процессы в многофазно-однофазных реверсивных электромашинно-вентильных преобра-
зователях бесконтактных машин двойного питания
Transport of Nordic Seas Overflow Water Into and Within the Irminger Sea: An Eddy-Resolving Simulation and Observations
Results from a climatologically forced, eddy-resolving (1/12 degrees) Atlantic simulation using the Hybrid Coordinate Ocean Model help clarify some presently unresolved connections between volume transports of Nordic Seas overflow water at key locations in the northernmost North Atlantic Ocean. The model results demonstrate that, in addition to the known westward flow through the Charlie Gibbs Fracture Zone (CGFZ), some Iceland Scotland overflow water (ISOW) flows westward through gaps in the Reykjanes Ridge north of the CGFZ into the Irminger Sea, and some flows southward along the eastern flank of the Mid-Atlantic Ridge into the West European Basin. These results provide insights into the well-known inconsistency between observed westward transport of ISOW through the CGFZ (2.4 Sv) and the transports upstream at Southeast of Iceland section (3.2 Sv) and downstream in the western Irminger Sea (4.5 Sv). Although the portion of the simulated ISOW that flows through CGFZ is about 500 m deeper than observed, the model results also show two ISOW pathways of this flow into the Irminger Sea, one northward along the western flank of the Reykjanes Ridge and the other westward before turning north-eastward on the western side of the Irminger Basin. Comparisons with the long-term moored instrument database in the Irminger Sea show that the model-based mean circulation is in reasonable agreement with observed volume transports of overflow water and that it gives approximately correct temperature and salinity characteristics
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