Magnetocaloric effect and magnetization in a Ni-Mn-Ga Heusler alloy in the vicinity of magnetostructural transition

The magnetic and thermodynamic properties of a Ni2.19Mn0.81Ga alloy with coupled magnetic and structural (martensitic) phase transitions were studied experimentally and theoretically. The magnetocaloric effect was measured by a direct method in magnetic fields 0-26 kOe at temperatures close to the magnetostructural transition temperature. For theoretical description of the alloy properties near the magnetostructural transition a statistical model is suggested, that takes into account the coexistence of martensite and austenite domains in the vicinity of martensite transformation point.Comment: presented at ICM-2003, to appear in JMM

General statistical-thermodynamical treatment of one-dimensional multicomponent molecular hetero-assembly in solution

A general treatment has been developed for the multicomponent one-dimensional non-covalent molec-ular hetero-assembly in solution using transfer matrix and sequence generating function approaches. The main result is set of equations, which allows one to obtain any thermodynamical quantities of the mul-ticomponent system and, in particular, experimental observable enabling one to get all equilibrium parameters of molecular interaction. The matrix form of presentation of the key equations allows their direct incorporation into matrix-oriented mathematical software, which leads to a two orders of magni-tude increase in speed of calculation of as compared to other known approache

Evidence of entropically driven C₆₀ fullerene aggregation in aqueous solution

In the present work, we report the first experimental evidence of entropically driven C₆₀ fullerene aggregation in aqueous solution, occurring with nearly zero enthalpy chang

Complexation of aromatic drugs with single-walled carbon nanotubes

We report a detailed study of the complexation of aromatic molecules and drugs with the surface of single-walled carbon nanotubes (SWCNTs, the diameter and the length ranges are 0.5-2 nm and 1-5 μm, respectively) in terms of equilibrium binding constants, K. It is found that the binding constants have magnitudes of the order of 104-105 M-1 and that there is some ligand specificity to the SWCNT surface depending on the structure of the aromatic molecul

First Principles Investigation of Magnetic Properties of Fe-Ni-Mn-Al Heusler Alloys

AbstractThe composition dependences of crystal lattice parameters, magnetic moments and magnetic exchange parameters in FexNi2−xMn1+y Al1−y (0.0 ≤ x ≤ 2.0; 0.0 ≤ y ≤ 0.6) Heusler alloys are investigated with the help of first principles calculations. Our simulations have shown that crystal lattice parameter is decreased with Fe content (x) increasing. Our calculations show that increase of Fe content (x) leads increasing of magnetic exchange interactions between Mn atoms at regular positions and Mn atoms at Al positions and change of interaction sign from antiferromagnetic type to ferromagnetic one for Fe content x ≥ 1.4. Competitive behavior between ferromagnetic and antiferromagnetic interactions shows that these alloys have a complex magnetic structure. Calculated data for crystal lattice parameter, magnetic moment and magnetic exchange parameters for pure compounds (x = 0.0 and x = 2.0) are in an agreement with theoretical and experimental data

Interceptor effect of C₆₀ fullerene on the in vitro action of aromatic drug molecules

In this work we are focusing on studying the influence of the pristine C₆₀ fullerene on biological activity of some aromatic drug molecules in human buccal epithelial cells. Assessment of the heterochromatin structure in the cell nucleus as well as the barrier function of the cell membrane was performed. The methods of cell microelectrophoresis and atomic force microscopy were also applied. A concentration-dependent restoration of the functional activity of the cellular nucleus after exposure to DNA -binding drugs (doxorubicin, proflavine and ethidium bromide) has been observed in human buccal epithelial cells upon addition of C₆₀ fullerene at a concentration of ~10−5