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41.
42.
Joined with measures of specific heat at low temperature , a calorimetric study of alkali sulphates from ordinary temperature to 1500 K has allowed the calculation of enthalpy, entropy and Gibbs free energy of these salts. The value of entropy at melting point is compared with the value assessed by an acoustical method. 相似文献
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Classical continuum elastic calculations show that the acoustic vibrational modes of an embedded nanoparticle can be lightly damped even when the longitudinal plane wave acoustic impedances Z(o)=rhov(L) of the nanoparticle and the matrix are the same. It is not necessary for the matrix to be less dense or softer than the nanoparticle in order to have long lived vibrational modes. A corrected formula for acoustic impedance is provided for the case of longitudinal spherical waves. Continuum boundary conditions do not always accurately reflect the microscopic nature of the interface between the nanoparticle and the matrix, and a multilayer model of the interface reveals the possibility of additional reduction of mode damping. 相似文献
47.
We define cheat sensitive cryptographic protocols between mistrustful parties as protocols which guarantee that, if either cheats, the other has some nonzero probability of detecting the cheating. We describe an unconditionally secure cheat sensitive nonrelativistic bit commitment protocol which uses quantum information to implement a task which is classically impossible; we also describe a simple relativistic protocol. 相似文献
48.
Blindauer CA Polfer NC Keiper SE Harrison MD Robinson NJ Langridge-Smith PR Sadler PJ 《Journal of the American Chemical Society》2003,125(11):3226-3227
Using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry, we show that one Zn2+ ion in the Zn4 cluster of cyanobacterial metallothionein is inert to exchange with 67Zn2+. We suggest that this is zinc in site A, which together with the surrounding alpha and beta secondary structure forms a zinc-finger fold. 相似文献
49.
G. B. Parravicini A. Stella M. C. Ungureanu P. G. Merli A. Migliori P. Cheyssac R. Kofman 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,24(1-3):219-222
Both theoretical and experimental works give evidence that
gallium exhibits solid phases labelled , , , besides the
stable phase strongly dependent both on the size and the
confinement conditions. An experimental technique was used based
on capacitance and conductance measurements
vs. temperature in the
audiofrequency range. This technique is particularly sensitive
to the conditions of the investigated particle surface that
plays a fundamental role in the melting and more generally in
the phase transition processes. In particular the strict
relation between the derivative of the capacitance with respect
to the temperature, dC/dT, and the entropy of the system is
considered. In gallium nanoparticles 20 nm in radius, only the
phase is shown to occur. Further the transition to liquid phase
was detected. The melting process was found to start about 65 K
below the full melting temperature value. In the case of
particles 10 nm in radius, where different metastable phases may
occur, the capacitance vs.
temperature curve was found to display abrupt changes of the
slope. The singularities are associated to a well defined
transition temperature. 相似文献
50.
Catherina?BandleEmail author Stella?Vernier-Piro 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2003,54(5):815-821
A Rayleigh-Faber-Krahn type inequality is used to
derive bounds for boundary value problems appearing in
reaction-diffusion problems where the reactant is consumed.
Interesting quantities are the minimum of the solution and the
measure of the set where it vanishes. The proofs are rather
elementary and apply to problems possessing solutions in a weak
sense. 相似文献