54,864 research outputs found
Photo-driven Molecular Wankel Engine B
We report a molecular Wankel motor, the dual-ring structure B13+, driven by
circularly-polarized infrared electromagnetic radiation, under which a guided
uni-directional rotation of the outer ring is achieved with rotational
frequency of the order of 300 MHz.Comment: 5 pages, 4 figure
A Manganin Foil Sensor for Small Uniaxial Stress
We describe a simple manganin foil resistance manometer for uniaxial stress
measurements. The manometer functions at low pressures and over a range of
temperatures. In this design no temperature seasoning is necessary, although
the manometer must be prestressed to the upper end of the desired pressure
range. The prestress pressure cannot be increased arbitrarily; irreversibility
arising from shear stress limits its range. Attempting larger pressures yields
irreproducible resistance measurements.Comment: 3 pages, 3 figure
Bi(111) thin film with insulating interior but metallic surfaces
The electrical conductance of molecular beam epitaxial Bi on BaF2(111) was
measured as a function of both film thickness (4-540 nm) and temperature (5-300
K). Unlike bulk Bi as a prototype semimetal, the Bi thin films up to 90 nm are
found to be insulating in the interiors but metallic on the surfaces. This
result has not only resolved unambiguously the long controversy about the
existence of semimetal-semiconductor transition in Bi thin film but also
provided a straightforward interpretation for the long-puzzled temperature
dependence of the resistivity of Bi thin films, which in turn might suggest
some potential applications in spintronics
Real time description of fission
Using the time-dependent superfluid local density approximation, the dynamics
of fission is investigated in real time from just beyond the saddle to fully
separated fragments. Simulations produced in this fully microscopic framework
can help to assess the validity of the current approaches to fission, and to
obtain estimate of fission observables. In this contribution, we concentrate on
general aspects of fission dynamics.Comment: Proceedings of the "15th Varenna Conference on Nuclear Reaction
Mechanisms," Varenna, Italy, June 201
Nuclear Fission: from more phenomenology and adjusted parameters to more fundamental theory and increased predictive power
Two major recent developments in theory and computational resources created
the favorable conditions for achieving a microscopic description of nuclear
fission almost eighty years after its discovery in 1939 by Hahn and Strassmann
(1930). The first major development was in theory, the extension of the
Time-Dependent Density Functional Theory (TDDFT) to superfluid fermion systems.
The second development was in computing, the emergence of powerful enough
supercomputers capable of solving the complex systems of equations describing
the time evolution in three dimensions without any restrictions of hundreds of
strongly interacting nucleons. Even though the available nuclear energy density
functionals (NEDFs) are phenomenological still, their accuracy is improving
steadily and the prospects of being able to perform calculations of the nuclear
fission dynamics and to predict many properties of the fission fragments,
otherwise not possible to extract from experiments, are within reach, all
without making recourse anymore to uncontrollable assumptions and simplified
phenomenological models.Comment: 6 pages, account of invited talk given at FUSION17, Hobart, Tasmania,
February 20-24, 201
- …