85 research outputs found
A multi-scale study on the bubble dynamics of cryogenic cavitation
This study aims to construct a multi-scale cavitation model for unsteady cryogenic cavitation CFD. Many elementary physical processes of bubbles (i.e, nucleation, growth/shrink, evaporation/condensation, coalescence/fission, collapse, bubblebubble interaction, bubble-turbulence interaction, and so on) emerge in cryogenic cavitation where some of the processes have not been understood well. In this paper, we mainly focused the molecular processes in homogeneous liquid-vapor nucleation with noncondensable gas solution by using Molecular Dynamics (MD) method. Bubble nucleation in liquid oxygen including helium, nitrogen, or argon was simulated. Molecular interaction was given by Lennard-Jones potential, and basically, each potential parameter was defined so that a saturation curve obtained by MD data was consistent with an experimental value. In the case that helium was impurity, a bubble nucleus was formed by density fluctuation at a lower concentration while a cluster constituted with helium molecules formed a bubble nucleus at a higher concentration, and the nucleation point becomes closer to the saturation point of pure oxygen when helium molecules form clusters. On the other hand, in the case that nitrogen or argon was the impurity, the above-mentioned clustering was not observed clearly at a concentration where helium made clusters, and these impurities have weaker action to make clusters and cavitation bubble nuclei compared with helium.http://deepblue.lib.umich.edu/bitstream/2027.42/84285/1/CAV2009-final102.pd
Superconductivity in Ternary Scandium Telluride Sc6MTe2 with 3d, 4d, and 5d Transition Metals
We report the discovery of bulk superconductivity in Sc6MTe2 with seven kinds
of transition-metal elements M. The critical temperatures for M = 3d elements
are higher than those for 4d and 5d elements and increase in the order of M =
Ni, Co, and Fe with the highest Tc of 4.7 K in Sc6FeTe2. First principles
calculations indicate the presence of significant contribution of Fe 3d
orbitals at the Fermi energy, which most likely enhance the Tc of Sc6FeTe2. The
upper critical field for M = Os is considerably enhanced by the strong
spin-orbit coupling. These results show Sc6MTe2 to constitute a unique family
of d-electron superconductors, in which d electrons of 3d and 5d M atoms
strongly influence the superconducting properties.Comment: 8 pages, 10 figure
One-Center Charge Transfer Transitions in Manganites
In frames of a rather conventional cluster approach, which combines the
crystal field and the ligand field models we have considered different charge
transfer (CT) states and O 2p-Mn 3d CT transitions in MnO octahedra.
The many-electron dipole transition matrix elements were calculated using the
Racah algebra for the cubic point group. Simple "local" approximation allowed
to calculate the relative intensity for all dipole-allowed and
CT transitions. We present a self-consistent description of
the CT bands in insulating stoichiometric LaMnO compound with the
only Mn valent state and idealized octahedral MnO centers
which allows to substantially correct the current interpretation of the optical
spectra. Our analysis shows the multi-band structure of the CT optical response
with the weak low-energy edge at 1.7 eV, associated with forbidden
transition and a series of the weak and strong
dipole-allowed high-energy transitions starting from 2.5 and 4.5 eV,
respectively, and extending up to nearly 11 eV. The most intensive features are
associated with two strong composite bands near eV and
eV, respectively, resulting from the superposition of the dipole-allowed
and CT transitions. These predictions are in good
agreement with experimental spectra. The experimental data point to a strong
overscreening of the crystal field parameter in the CT states of
MnO centers.Comment: 10 pages, 3 figure
A Radiological Study of Rapidly Destructive Coxarthropathy
Rapidly destructive coxarthropathy (RDC) is a clinical concept propounded by Postel and Kerboull. RDC is characterized by joint destruction progression within a year, although the etiology of this disorder remains unknown. We evaluated 21 hips in 20 patients radiologically diagnosed with RDC. All patients underwent a total hip arthroplasty. The average age at surgery was 75 years. The affected side was more osteoporotic in all patients, and the pelvic angle, which indicates the spinopelvic alignment, was distributed below the normal range, i.e., the posterior tilt was more than the normal range. The affected side showed a higher center-edge (CE) angle and anterior-acetabular head index (AAHI) than the unaffected side, possibly due to severe head collapse. Our result supported that osteoporosis and/or mechanical factors influence the course of RDC. More investigations such as biochemical and immunopathological analyses would be necessary to clarify the etiology of RDC, which could be a terminal stage of some lesions
Massive Neurilemoma of the Hard Plate in Which Preoperative Diagnosis Was Difficult
The patient was an 84-year-old man who was referred to our hospital in mid-December 2012 for a close examination of a mass arising from the left side of the hard palate that was found by a local dentist. The initial examination revealed the presence of a 3.0-cm elastic soft, dome-shaped mass in the left hard palate. CE-CT showed a lesion of size 1.8 × 1.4 cm in the right hard palate, which extended upward and invaded the nasal cavity. The mass was a solid tumor associated with resorption of surrounding bone and expansion of the greater palatine canal. CE-MRI indicated that the mass extended upward and invaded the nasal cavity, and the mass showed hypointensity on T1-weighted images, hyperintensity on T2-weighted images, and an irregular margin with internal enhancement. Abnormal uptake of FDG on PET-CT (SUVmax = 5.2) was observed in the left hard palate. The biopsy site lesion rapidly increased in size and biopsy was performed again in January 2013 due to suspicion of a malignant tumor. The histopathological diagnosis was a suspected malignant neurogenic tumor. Therefore, the patient underwent partial maxillectomy and a split-thickness skin graft in late February 2013. No recurrence was noted 29 months after the operation
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