Effect of pressure on the Curie temperature of annealed Fe-Ni-Cr-Mo-Si-B amorphous alloys

Effect of high pressure on the Curie temperature of annealed Fe₃₀Ni3₆Cr₁₂Mo₂Si₅B₁₅ amorphous alloys has been investigated. It has been shown that the annealed samples e hibit a smaller pressure dependence ofT _c than as-quenched one.Dedicated to Dr. S. Krupika on the occasion of his 65th birthday.We would like to thank Dr. P. Duhaj (Institute of Physics, Slovak Academy of Sciences, Bratislava) for the preparation of amorphous samples and Mrs. H. Kuchárska for technical assistance.     

Reactivity of Cl(2P1/2) atoms towards CH3F

The photochlorination of methyl fluoride has been studied at low pressures. Excited (²P_1/2) chlorine atoms have been found to participate in the reaction. The ratio of the excited and ground state rate constants has been estimated at room temperature.

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. (²P_1/2) . .

     

Studies of the reactions of Br(2P32) and Br(2P12) atoms with CH3F

The photobromination of methyl fluoride at low pressures has been studied experimentally. Bromine atoms in the ground (²P_{$\text{3}\text{2}$}) and excit     

Reactivity of electronically excited Br(2P1/2) atoms towards CH3F

The rate constants for Br(²P_1/2) and Br(²P_3/2) atoms in the reaction Br+CH₃FHBr+CH₂F in photobromination of CH₃F have been determined. Their ratio is 10^{–(2.6±0.5)} exp(10100±1000/RT) in the temperature range of 60–200 °C.

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Br(²P_1/2) Br(²P_3/2) Br+CH₃FHBr+CH₂F CH₃F. 60–200 °C 10^{–(2,6±0,5)} exp (10100±1000/RT).

     

Resistive properties of La2 ? x Sr x CuO4 low-dopped cuprates in the antiferromagnetic state at low temperatures

The nonlinear dependence of conductivity and negative differential resistance of ceramic samples of La_{2 ? x} Sr _x CuO₄ in the antiferromagnetic state is revealed. The possible influence of a spatially inhomoge-neous distribution of strontium impurities on the low-temperature behavior of conductivity is discussed.     

Effect of metakaolin structure on its binding properties in alkaline hydration

Aluminum ion coordination to oxygen in metakaolin of different origin was studied by a solid-state ²⁷Al NMR spectroscopy, as well as changes in aluminum ion coordination in an interaction of metakaolins with sodium silicate solution. At the same time a durability of structures resulting from this interaction was examined. Based on the findings the relationship between the structure of metakaolin and its astringent properties in alkaline environment was considered.     

Eikonal formulation of the minimal principle for scroll wave filaments

Recently, Wellner et al. [Proc. Natl. Acad. Sci. U.S.A. 99, 8015 (2002)]] proposed a principle for predicting a stable scroll wave filament shape as a geodesic in a 3D space with a metric determined by the inverse diffusivity tensor of the medium. Using the Hamilton-Jacobi theory we show that this geodesic is the shortest path for a wave propagating through the medium. This allows the use of shortest path algorithms to predict filament shapes, which we confirm numerically for a medium with orthotropic anisotropy. Our method can be used in cardiac tissue experiments since it does not require knowledge of the tissue anisotropy.