367 research outputs found
Self-assembly of iron nanoclusters on the Fe3O4(111) superstructured surface
We report on the self-organized growth of a regular array of Fe nanoclusters
on a nanopatterned magnetite surface. Under oxidizing preparation conditions
the (111) surface of magnetite exhibits a regular superstructure with
three-fold symmetry and a 42 A periodicity. This superstructure represents an
oxygen terminated (111) surface, which is reconstructed to form a periodically
strained surface. This strain patterned surface has been used as a template for
the growth of an ultrathin metal film. A Fe film of 0.5 A thickness was
deposited on the substrate at room temperature. Fe nanoclusters are formed on
top of the surface superstructure creating a regular array with the period of
the superstructure. We also demonstrate that at least the initial stage of Fe
growth occurs in two-dimensional mode. In the areas of the surface where the
strain pattern is not formed, random nucleation of Fe was observed.Comment: 6 pages, 3 figure
Atomically Resolved Spin-Dependent Tunnelling on the Oxygen-Terminated Fe3O4 (111)
We employ spin-polarized (SP) STM to study the spin-dependent tunneling
between a magnetite (111) sample and an antiferromagnetic tip through a vacuum
barrier at room temperature. Atomic scale STM images show significant magnetic
contrast corresponding to variations in the local surface states induced by
oxygen vacancies. The estimated variations in tunneling magnetoresistance (TMR)
of 250% suggest that the spin-transport properties are significantly altered
locally by the presence of surface defects.Comment: 10 pages, 4 figure
Materials of the final reports on the joint Soviet-American experiment on the Kosmos-936 biosatellite
Biological experiments onboard the Kosmos-936 investigated the effect of weightlessness on the basic components of cells, the genetic structure and energy apparatus. Genetic studies were made on the Drosophila melanogaster. Experiments were made on higher vegetation and fungi as well. The results indicate that weightlessness cannot be the principal barrier for normal development. An experiment with ectopic osteogenesis in weightlessness was carried out. Measurements were made of cosmic radiation inside and outside the biosatellite
Method for increasing sensitivity of shear-force distance control for scanning near-field microscopy
Scanning-near field optical microscopy requires a distance control mechanism. In most cases, it is based on the shear-force detection. In this paper we report how the performance of the shear-force detection based on the most common nonoptical approach, a Quartz tuning fork, can be improved. Our approach is based on exciting oscillations in just one arm of the fork, not two. This approach reduces the response time of the shear-force detection system. We also introduce an ultra-sensitive system with a long free fiber tip. © 1999 Elsevier Science B.V. All rights reserved
Atomic and electronic structure of nanostructured few-layer graphene with self-aligned boundaries synthesized on SiC/Si(001) wafers
This work was partially supported by the Russian Academy of Sciences, Russian Foundation for Basic Research (grant № 17-02-01139, 17-02-01291), Beijing Institute of Technology Research Fund Program for Young Scholars, and Science Foundation Ireland
Step bunching with both directions of the current: Vicinal W(110) surfaces versus atomistic scale model
We report for the first time the observation of bunching of monoatomic steps
on vicinal W(110) surfaces induced by step up or step down currents across the
steps. Measurements reveal that the size scaling exponent {\gamma}, connecting
the maximal slope of a bunch with its height, differs depending on the current
direction. We provide a numerical perspective by using an atomistic scale model
with a conserved surface flux to mimic experimental conditions, and also for
the first time show that there is an interval of parameters in which the
vicinal surface is unstable against step bunching for both directions of the
adatom drift.Comment: 17 pages, 10 figure
Incorporating prior knowledge improves detection of differences in bacterial growth rate
BACKGROUND: Robust statistical detection of differences in the bacterial growth rate can be challenging, particularly when dealing with small differences or noisy data. The Bayesian approach provides a consistent framework for inferring model parameters and comparing hypotheses. The method captures the full uncertainty of parameter values, whilst making effective use of prior knowledge about a given system to improve estimation. RESULTS: We demonstrated the application of Bayesian analysis to bacterial growth curve comparison. Following extensive testing of the method, the analysis was applied to the large dataset of bacterial responses which are freely available at the web-resource, ComBase. Detection was found to be improved by using prior knowledge from clusters of previously analysed experimental results at similar environmental conditions. A comparison was also made to a more traditional statistical testing method, the F-test, and Bayesian analysis was found to perform more conclusively and to be capable of attributing significance to more subtle differences in growth rate. CONCLUSIONS: We have demonstrated that by making use of existing experimental knowledge, it is possible to significantly improve detection of differences in bacterial growth rate
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