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51.
Kim C Liu Y Kühnle A Hess S Viereck S Danner T Mahadevan L Weitz DA 《Physical review letters》2007,99(2):028303
Colloidal suspensions are susceptible to gravitationally induced phase separation. This can be mitigated by the formation of a particle network caused by depletion attraction. The effectiveness of this network in supporting the buoyant weight of the suspension can be characterized by its compressional modulus. We measure the compressional modulus for emulsion networks induced by depletion attraction and present a model that quantitatively predicts their gravitational stability. We also determine the relationship between the strength of the depletion attraction and the magnitude of the compressional modulus. 相似文献
52.
Measurement of the critical fracture strength of single-crystal silicon was carried out by contact-free laser-based excitation and detection of nonlinear surface acoustic wave (SAW) pulses. The three crystallographic geometries Si(112)111[over ], Si(112)1[over ]1[over ]1, and Si(110)11[over ]1 were examined. A comparison of the optically detected SAW transients and numerically calculated stress-strain fields allowed an estimate of the intrinsic mechanical strength without using an artificial precrack. Depending on the geometry, the critical strength varied between 5 and 7 GPa. 相似文献
53.
E. A. Popova N. Tristan C. Hess R. Klingeler B. Büchner L. N. Bezmaternykh V. L. Temerov A. N. Vasil’ev 《Journal of Experimental and Theoretical Physics》2007,105(1):105-107
The neodymium ferroborate NdFe3(BO3)4 undergoes an antiferromagnetic transition at T N = 30 K, which manifests itself as a λ-type anomaly in the temperature dependence of the specific heat C and as inflection points in the temperature dependences of the magnetic susceptibility χ measured at various directions of an applied magnetic field with respect to the crystallographic axes of the sample. Magnetic ordering occurs only in the subsystem of Fe3+ ions, whereas the subsystem of Nd3+ ions remains polarized by the magnetic field of the iron subsystem. A change in the population of the levels of the ground Kramers doublet of neodymium ions manifests itself as Schottky-type anomalies in the C(T) and χ(T) dependences at low temperatures. At low temperatures, the magnetic properties of single-crystal NdFe3(BO3)4 are substantially anisotropic, which is determined by the anisotropic contribution of the rare-earth subsystem to the magnetization. The experimental data obtained are used to propose a model for the magnetic structure of NdFe3(BO3)4. 相似文献
54.
Two samples of mussels (Mytilus edulis) were collected from the southwest of Ireland. One sample contained domoic acid, the other sample contained okadaic acid,
dinophysistoxin-2 and azaspiracid-1, -2 and -3. Wet and freeze-dried reference materials were prepared from each of the two
samples to test for differences in homogeneity, stability and extractability of the analytes in either condition. Wet materials
were homogenised, aliquoted and hermetically sealed under argon and subsequently frozen at −80 °C. Dry materials were similarly
homogenised but frozen in flat cakes prior to freeze-drying. After grinding, sieving and further homogenisation, the resulting
powder was aliquoted and hermetically sealed. Domoic acid materials were characterised using HPLC–UV, while LC–MS was used
for the determination of lipophilic toxins. The extractabilities of all phycotoxins studied were comparable for wet and freeze-dried
materials once a sonication step had been carried out for reconstitution of the freeze-dried materials prior to extraction.
Homogeneity was assessed through replicate analysis of the phycotoxins (n = 10), and was found to be similar for wet and freeze-dried materials, for both hydrophilic and lipophilic toxins. Water
contents were determined for both wet and freeze-dried materials, and particle size was determined for the freeze-dried materials.
Stability was evaluated isochronously over eight months at four temperatures (−20, +4, +20 and +40 °C). The freeze-dried material
containing domoic acid was stable over the whole duration at all temperatures, while in the wet material domoic acid degraded
to some extent at all temperatures except −20 °C. In freeze-dried and wet materials containing lipophilic toxins, okadaic
acid, dinophysistoxin-2, azaspiracid-1 and azaspiracid-2 were stable over the whole duration at all conditions, while concentrations
of azaspiracid-3 changed significantly in both materials at some storage temperatures.
Figure Aliquots of freeze-dried and wet mussel tissue reference materials containing the various shellfish toxins examined in the
study 相似文献
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59.
The differences between a full Lorentz-Lorenz potential modification, and a ?2 approximation to this modification are examined for low energy pion-nucleus elastic scattering. The relationship between these approaches and the single-scattering impulse approximation is also investigated. 相似文献
60.
Consider a continuous local martingale X. We say that X satisfies the representation property if any martingale Y of X can be represented as stochastic ITǒ integral of X. Using the method of random time change systematically, in the present paper the representation problem for continuous local martingales is treated. We describe a class of martingales Y that can be represented as stochastic integral of X by probabilistic conditions. This leads to sufficient conditions for the representation property of X being true. Besides, an interesting characterization of continuous processes with independent increments is obtained. In part II. we proceed with general examples, applications to the n-dimensional case, and, in particular, to the n-dimensional time change of continuous local martingales with orthogonal components. 相似文献