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1.
The transformation of amorphous thin alloy films of Co–Zr to the crystalline state was observed with an electron microscope in the diffraction mode. This investigation elucidates the crystallization temperatures,T
x
, of thin films as opposed to theT
x
presented for thicker samples; usually melt-quenched in the thickness range of 20–50 m. TheT
x
of the thin films are compared also with theT
x
for sputtered alloys of Co–Zr at 5 m. 相似文献
2.
This paper reviews the theory and practice of Lorentz electron microscopy in the investigations of magnetic domain structure. The transmission electron microscope, the necessary operational procedures and imaging theory required for Lorentz microscopy are described. Magnetization devices and other facilities that have been developed over the last two years to study domain magnetization in situ in the electron microscope are discussed. Results so far obtained on such materials as thin single crystals and polycrystals of ferromagnetic metals, magnetic oxides, evaporated and electrodeposited single crystal and polycrystal films, and whisker and single domain particles are reviewed. The methods available for preparing specimens in a suitable form for transmission electron microscopy are described. 相似文献
3.
In this paper we extend the plane blow-up results of Grundy& McLaughlin (1997) to the three-dimensional Navier-Stokes equations.Using a solution structure originally due to Lin we first providenumerical evidence for the existence of blow-up solutions on- < x, z < , 0 y 1 with boundary conditions on y = 0and y = 1 involving derivatives of the velocity components.The formulation enables us to consider plane and radial flowas special cases. Various features of the computations are isolatedand are used to construct a formal asymptotic solution closeto blow-up. We show that the numerical and asymptotic analysesprovide a mutually consistent global picture which supportsthe conclusion that, for the family of problems we considerhere, blow-up in fact can take place in three dimensions butat an inverse linear rate rather than the faster inverse squareof the plane case. 相似文献
4.
Tosylmethylisocyanide, when coordinated to osmium(II), reacts with aldehydes and ketones in the presence of sodium methoxide, to produce oxazol-2-ylidene and oxazolidin-2-ylidene complexes. 相似文献
5.
Polystyrene particles of 9 μm diameter were acoustically concentrated along the axis of a water-filled cylindrical waveguide containing a 3 MHz standing wave field. Modulation of the acoustic field enabled transport of the concentrated particles in the axial direction. Four modulations were investigated; 1, a fixed frequency difference introduced between two transducers; 2, ramping the transducer frequency; 3, tone burst, i.e. sound that is pulsed on and off, allowing intermittent sedimentation under gravity; and 4, switching the sound off to allow continuous sedimentation. The most efficient transport (leaving the fewest particles in suspension) of clumps to one end of the container was achieved with method 1 above. In this system the maximum speed of transport of the axial clumps was 24 mm s-1. A theory developed here for the transport of particles in a pseudo (i.e. slowly moving) standing wave field predicts an upper limit, which increases with particle size, for the speed of an entrained body. For a single 9 μm diameter particle in a field with a spatial peak pressure amplitude of 0.4 MPa this speed would be 0.5 mm s-1. The higher experimental speeds observed here emphasize the value of acoustically concentrating particles into relatively large clumps prior to initiating transport. 相似文献
6.
F-riebeckite has been subjected to analysis by 57-Fe Moessbauer spectroscopy from 4. 2K to 501K. The spectra obtained above
the magnetic transition temperature, were analyzed in terms of three ferrous doublets in M1, M3 and M2 sites and two ferric
doublets occupying M2 and M1 sites. The ratios of these occupations, together with their quadrupole splittings, were then
used to fit the 4.2K magnetic spectrum. 相似文献
7.
The paper determines the location of the steady state interface between fresh and saltwater in a plane coastal aquifer. The lower boundary is totally impervious while the upper one is impervious below land and semi-pervious below the sea allowing an outflow through this part of the upper boundary. The model equations reduce to two boundary value problems, one valid in x < 0 and the other in x > 0 here x is measured along the aquifer with the origin at the coast. In each region unknown boundaries have to be determined as part of the solution using boundary and continuity conditions. Two cases are presented using the Dupuit approximation. One where the solution can be written down in terms of elementary functions and the other in which we have to use a phase space analysis. 相似文献
8.
Baumberg JJ Kavokin AV Christopoulos S Grundy AJ Butté R Christmann G Solnyshkov DD Malpuech G von Högersthal GB Feltin E Carlin JF Grandjean N 《Physical review letters》2008,101(13):136409
We observe the buildup of strong (approximately 50%) spontaneous vector polarization in emission from a GaN-based polariton laser excited by short optical pulses at room temperature. The Stokes vector of emitted light changes its orientation randomly from one excitation pulse to another, so that the time-integrated polarization remains zero. This behavior is completely different from any previous laser. We interpret this observation in terms of the spontaneous symmetry breaking in a Bose-Einstein condensate of exciton polaritons. 相似文献
9.
10.
Phospha(III)guanidines, R2PC{NR'}{NHR'}, have been used to synthesize multimetallic compounds containing combinations of aluminum with platinum or copper, in which the main-group metal is N,N'-bound by an amidinate moiety, thereby generating a metal-functionalized phosphine that bonds to the transition metal through phosphorus. 相似文献