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排序方式: 共有118条查询结果,搜索用时 171 毫秒
61.
Adamson P Auty DJ Ayres DS Backhouse C Barr G Betancourt M Bishai M Blake A Bock GJ Boehnlein DJ Bogert D Cao SV Cavanaugh S Cherdack D Childress S Coelho JA Corwin L Cronin-Hennessy D Danko IZ de Jong JK Devenish NE Diwan MV Dorman M Escobar CO Evans JJ Falk E Feldman GJ Frohne MV Gallagher HR Gomes RA Goodman MC Gouffon P Graf N Gran R Grzelak K Habig A Hartnell J Hatcher R Himmel A Holin A Huang X Hylen J Irwin GM Isvan Z Jaffe DE James C Jensen D Kafka T Kasahara SM Koizumi G Kopp S 《Physical review letters》2011,107(18):181802
We report the results of a search for ν(e) appearance in a ν(μ) beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of 8.2 × 10(20) protons on the NuMI target at Fermilab, we find that 2 sin(2) (θ(23))sin(2)(2θ(13))<0.12(0.20) at 90% confidence level for δ = 0 and the normal (inverted) neutrino mass hierarchy, with a best-fit of 2sin(2) (θ(23))sin(2)(2θ(13)) = 0.041(-0.031)(+0.047) (0.079(-0.053) (+0.071)). The θ(13) = 0 hypothesis is disfavored by the MINOS data at the 89% confidence level. 相似文献
62.
Peep Adamson 《Optical and Quantum Electronics》2018,50(11):403
New possibilities for determining anisotropic properties of the dielectric constants of two-dimensional materials by ellipsometry are developed. Graphene-like 2D materials are considered within the framework of macroscopic electrodynamics as ultrathin absorbing anisotropic films where the optical axis is perpendicular to the film surface. The ellipsometric inversion problem is resolved analytically. The resulting inversion formulas are very fast because they allow you to directly calculate the complex anisotropic dielectric constants without the use of sophisticated regression analysis or iterative root-finding procedures. In particular, the method offers an interest in graphene and related 2D materials because the anisotropic properties of such materials have not been studied to date. 相似文献
63.
Correlation‐free reflection diagnostics of graphene‐like surface layers in the infrared region 下载免费PDF全文
Peep Adamson 《Surface and interface analysis : SIA》2015,47(13):1161-1165
New diagnostics possibilities for graphene‐like (two‐dimensional absorbing) ultrathin films on dielectric substrates by integrating ellipsometric and reflectance measurements are analyzed. The analysis is based on the analytical theory which has been developed in the framework of a long‐wavelength approximation. Importantly, the new method allows simultaneously (without correlation) to determine the thickness and optical constants of two‐dimensional materials in the infrared region. Another interesting feature of this reflection technique lies in the fact that for data handling the traditional model‐based regression analysis is not in use. The inversion problem is resolved on the basis of an analytical approach which has no need of initial guesses for the desired parameters. The results are also of interest as suitable starting points for non‐approximated numerical iterative methods where the proper choice of the initial data plays a crucial role. The presented method is tested using a numerical simulation. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
64.
We address the problem of completely characterizing multiparticle states including loss of information to unobserved degrees of freedom. In systems where nonclassical interference plays a role, such as linear-optics quantum gates, such information can degrade interference in two ways, by decoherence and by distinguishing the particles. Distinguishing information, often the limiting factor for quantum optical devices, is not correctly described by previous state-reconstruction techniques, which account only for decoherence. We extend these techniques and find that a single modified density matrix can completely describe partially coherent, partially distinguishable states. We use this observation to experimentally characterize two-photon polarization states in single-mode optical fiber. 相似文献
65.
D. D. Kharlampidi A. I. Dementiev S. O. Adamson 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(4):611-616
The possibility of using the uniformly charged sphere with the variable charge and constant radius for accurate phase shift and resonance states parameters calculations is investigated. It is demonstrated on the example of the Hazy-Taylor model problem that the proposed numerical technique provides the relative errors about 1% for the phase shift function and resonance state parameters (energy and width). The choice of the optimal basis set for such calculations is discussed also. 相似文献
66.
A prototype of a novel bone-conduction hearing actuator based on a piezoelectric bending actuator is presented. The device lies flat against the skull which would allow it to form the basis of a subcutaneous bone-anchored hearing aid. The actuator excites bending in bone through a local bending moment rather than the application of a point force as with conventional bone-anchored hearing aids. Through measurements of the cochlear velocity created by the actuator in embalmed human heads, the device is shown to exhibit high efficiency, making it a possible alternative to present-day electromagnetic bone-vibration actuators. 相似文献
67.
68.
Bulent Ozbas Shigeyuki Toki Benjamin S. Hsiao Benjamin Chu Richard A. Register Ilhan A. Aksay Robert K. Prud'homme Douglas H. Adamson 《Journal of Polymer Science.Polymer Physics》2012,50(10):718-723
The effects of functionalized graphene sheets (FGSs) on the mechanical properties and strain‐induced crystallization of natural rubber (NR) are investigated. FGSs are predominantly single sheets of graphene with a lateral size of several hundreds of nanometers and a thickness of 1.5 nm. The effect of FGS and that of carbon black (CB) on the strain‐induced crystallization of NR is compared by coupled tensile tests and X‐ray diffraction experiments. Synchrotron X‐ray scattering enables simultaneous measurements of stress and crystallization of NR in real time during sample stretching. The onset of crystallization occurs at significantly lower strains for FGS‐filled NR samples compared with CB‐filled NR, even at low loadings. Neat‐NR exhibits strain‐induced crystallization around a strain of 2.25, while incorporation of 1 and 4 wt % FGS shifts the crystallization to strains of 1.25 and 0.75, respectively. In contrast, loadings of 16 wt % CB do not significantly shift the critical strain for crystallization. Two‐dimensional (2D) wide angle X‐ray scattering patterns show minor polymer chain alignment during stretching, in accord with previous results for NR. Small angle X‐ray scattering shows that FGS is aligned in the stretching direction, whereas CB does not show alignment or anisotropy. The mechanical properties of filled NR samples are investigated using cyclic tensile and dynamic mechanical measurements above and below the glass transition of NR. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
69.
Bulent Ozbas Christopher D. O'Neill Richard A. Register Ilhan A. Aksay Robert K. Prud'homme Douglas H. Adamson 《Journal of Polymer Science.Polymer Physics》2012,50(13):910-916
We demonstrate the use of functionalized graphene sheets (FGSs) as multifunctional nanofillers to improve mechanical properties, lower gas permeability, and impart electrical conductivity for several distinct elastomers. FGS consists mainly of single sheets of crumbled graphene containing oxygen functional groups and is produced by the thermal exfoliation of oxidized graphite (GO). The present investigation includes composites of FGS and three elastomers: natural rubber (NR), styrene–butadiene rubber, and polydimethylsiloxane (PDMS). All of these elastomers show similar and significant improvements in mechanical properties with FGS, indicating that the mechanism of property improvement is inherent to the FGS and not simply a function of chemical crosslinking. The decrease in gas permeability is attributed to the high aspect ratio of the FGS sheets. This creates a tortuous path mechanism of gas diffusion; fitting the permeability data to the Nielsen model yields an aspect ratio of ~1000 for the FGS. Electrical conductivity is demonstrated at FGS loadings as low as 0.08% in PDMS and reaches 0.3 S/m at 4 wt % loading in NR. This combination of functionalities imparted by FGS is shown to result from its high aspect ratio and carbon‐based structure. © 2012 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2012 相似文献
70.
Structural Snapshots for Mechanism‐Based Inactivation of a Glycoside Hydrolase by Cyclopropyl Carbasugars 下载免费PDF全文
Christopher Adamson Robert J. Pengelly Saeideh Shamsi Kazem Abadi Dr. Saswati Chakladar Jason Draper Prof. Robert Britton Dr. Tracey M. Gloster Prof. Andrew J. Bennet 《Angewandte Chemie (International ed. in English)》2016,55(48):14978-14982
Glycoside hydrolases (GHs) have attracted considerable attention as targets for therapeutic agents, and thus mechanism‐based inhibitors are of great interest. We report the first structural analysis of a carbocyclic mechanism‐based GH inactivator, the results of which show that the two Michaelis complexes are in 2H3 conformations. We also report the synthesis and reactivity of a fluorinated analogue and the structure of its covalently linked intermediate (flattened 2H3 half‐chair). We conclude that these inactivator reactions mainly involve motion of the pseudo‐anomeric carbon atom, knowledge that should stimulate the design of new transition‐state analogues for use as chemical biology tools. 相似文献