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41.
Phase transitions of [M(H2O)6](MnO4)2, where M=Mg, Ni, Zn and Cd, have been studied at 100–400 K by differential scanning calorimetry (DSC). One solid–solid phase transition for the compounds with M=Mg and Ni and two solid–solid phase transitions for these with M=Zn and Cd have been discovered. Additionally, three phase transitions, connected with three-stage melting process of these compounds, were also found. Thermodynamic parameters of the all detected phase transitions were calculated. 相似文献
42.
Jaroszyński J Andrearczyk T Karczewski G Wróbel J Wojtowicz T Papis E Kamińska E Piotrowska A Popović D Dietl T 《Physical review letters》2002,89(26):266802
We report on the observation of the Ising quantum Hall ferromagnet with Curie temperature T(C) as high as 2 K in a modulation-doped (Cd,Mn)Te heterostructure. In this system field-induced crossing of Landau levels occurs due to the giant spin-splitting effect. Magnetoresistance data, collected over a wide range of temperatures, magnetic fields, tilt angles, and electron densities, are discussed taking into account both Coulomb electron-electron interactions and s-d coupling to Mn spin fluctuations. The critical behavior of the resistance "spikes" at T-->T(C) corroborates theoretical suggestions that the ferromagnet is destroyed by domain excitations. 相似文献
43.
Marek Gaździcki Mark I. Gorenstein Stanislaw Mrówczyński 《The European Physical Journal C - Particles and Fields》1998,5(1):129-133
The pion multiplicity per participating nucleon in central nucleus–nucleus collisions at the energies 2–15 AGeV is significantly smaller than in nucleon–nucleon interactions at the same collision energy. This effect of pion suppression is argued to appear due to the evolution of the system produced at the early stage of heavy–ion collisions towards a local
thermodynamic equilibrium and further isentropic expansion.
Received: 21 July 1997 / Revised version: 12 November 1997 / Published online: 26 February 1998 相似文献
44.
45.
Przerwa E Sosnowski S Slomkowski S 《Langmuir : the ACS journal of surfaces and colloids》2004,20(11):4684-4689
Formation of stripelike assemblies of poly(styrene/alpha-tert-butoxy-omega-vinyl-benzyl-polyglycidol) microspheres adsorbed on nonpatterned mica plates moving perpendicularly from suspension of particles through the water-air interface has been observed. It was found that ordered assemblies were formed by capillary forces acting on particles crossing the water-air boundary. At sufficiently high rates of plate movement (i.e., at appropriate dynamic loading conditions) the adsorbed microspheres approaching the water surface begin sliding on the plate, due to capillary forces, in the direction opposite to the plate movement and are kept below the water surface. Plate movement brings new adsorbed particles to the water-air interface, where particles are assembled into aggregates. When particle aggregates are large, the capillary forces cannot overcome shearing forces and the particle assemblies are withdrawn on the plate above the water surface. This process repeated during continuous movement of the plate results in the formation of the quite regularly distributed stripes of adsorbed microspheres. Formation of the regularly distributed particle assemblies depends on concentration of microspheres in suspension. 相似文献
46.
Let K be the field of real or complex numbers. Let (X K2n,) be a symplectic vector space and take 0 < k < n,N =. Let L1,...,LN X be 2k-dimensionallinear subspaces which are in a sufficiently general position.It is shown that if F : X X is a linear automorphism whichpreserves the form k on all subspaces L1,...,LN, then F is ank-symplectomorphism (that is, F* = k, where ). In particular, if K = R and k is odd then F mustbe a symplectomorphism. The unitary version of this theoremis proved as well. It is also observed that the set Al,2r ofall l-dimensional linear subspaces on which the form has rank 2r is linear in the Grassmannian G(l,2n), that is, there isa linear subspace L such that Al,2r = L G(l, 2n). In particular,the set Al,2r can be computed effectively. Finally, the notionof symplectic volume is introduced and it is proved that itis another strong invariant. 相似文献
47.
Andrzej Kryczka Stanislaw Prus 《Proceedings of the American Mathematical Society》2001,129(1):155-163
We prove that there is 1$"> such that the unit ball of any nonreflexive Banach space contains a -separated sequence. The supremum of these constants is estimated from below by and from above approximately by . Given any 1$">, we also construct a nonreflexive space so that if the convex hull of a sequence is sufficiently close to the unit sphere, then its separation constant does not exceed .
48.
Stanislaw Dzwigaj Lorenzo Stievano Michel Che 《Journal of Physics and Chemistry of Solids》2007,68(10):1885-1891
Fe-containing SiBEA zeolites were prepared by a two-step postsynthesis method: creation of vacant T-sites by dealumination of tetraethylammonium BEA zeolite with nitric acid and then impregnation of the resulting SiBEA zeolite with an aqueous solution of Fe(NO3)3. X-ray diffraction shows that iron is incorporated in SiBEA at lattice sites. The presence of Fe in its oxidation state +3 and at isolated tetrahedral sites for low metal content, was demonstrated by diffuse reflectance UV-vis, EPR and Mössbauer spectroscopy. For high iron content, diffuse reflectance UV-vis and Mössbauer spectra revealed the additional presence of extra-lattice FeOx oligomers and superparamagnetic Fe-oxyhydroxide. Mössbauer spectroscopy identified superparamagnetic Fe-oxyhydroxide as the main phase when basic conditions are used for the preparation. 相似文献
49.
Julia Pretula Krzysztof Kaluzynski Blazej Wisniewski Ryszard Szymanski Ton Loontjens Stanislaw Penczek 《Journal of polymer science. Part A, Polymer chemistry》2008,46(3):830-843
Conditions of synthesis of poly(ethylene phosphates) in reaction of H3PO4 with HOCH2CH2OH (EG), the actual path of polycondensation, and structure of the obtained polymers (mostly oligomers) and kinetics of reaction are described. Preliminary kinetic information, based on the comparison of the MALDI‐TOF‐ms and 31P{1H} NMR spectra as a function of conversion is given as well. Because of the dealkylation process fragments derived from di‐ and triethylene glycols are also present in the repeating units. Structures of the end groups (? CH2CH2OH or ? OP(O)(OH)2) depend on the starting ratio of [EG]0/[H3PO4]0, although even at the excess of EG the acidic end groups prevail because of the dealkylation process. In MALDI‐TOF‐ms products with Pn equal up to 21 have been observed. The average polymerization degrees (Pn) are lower and have been calculated from the proportion of the end groups. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 830–843, 2008 相似文献
50.