Structure and magnetic properties of multi-walled carbon nanotubes modified with iron

Magnetic properties of multi-walled carbon nanotubes modified with iron (MWCNT+Fe) are studied in detail in the temperature range 4.2–300 K. Carbon encapsulated Fe nanoparticles were obtained using chemical vapor deposition method. The low-temperature SQUID magnetization measurements are supplemented by structural investigations with thermogravimetric (TG) analysis, transmission electron microscopy (TEM), x-ray diffraction spectroscopy (XRD), and scanning electron microscopy (SEM). The magnetic susceptibility of MWCNT+Fe was also studied above room temperature to provide a complete picture of magnetic phase transitions

The Lake Baikal neutrino experiment

We rewiew the present status of the Baikal Neutrino Project and present the results of a search for high energy neutrinos with the detector intermediate stage NT-96.Comment: 3 pages, 2 figures, to appear in the Proceedings of Sixth International Workshop on Topics in Astroparticle and Underground Physics (TAUP99), September 6-10, 1999, Pais, Franc

On the asymptotics of solutions of boundary value problems for singularly perturbed linear systems on an infinite interval

[No abstract available

On the asymptotics of solutions of boundary value problems for singularly perturbed linear systems on an infinite interval

[No abstract available

An asymptotic analog of reducibility theorems for some classes of nonautonomous linear systems

[No abstract available

An asymptotic analog of reducibility theorems for some classes of nonautonomous linear systems

[No abstract available

Asymptotic analysis of linear periodic systems of homogeneous differential equations with a large or small parameter

The system dot x=(A_0+delta A_1(t))x, A_1in C^+(Bbb R), tin Bbb R^+, with a constant matrix A_0 and T-periodic matrix A_1, is studied. Two cases are considered. par First, if delta=varepsilon is a small parameter, under some assumptions concerning the spectrum of A_0 it is proved that even a more general system dot x=bigl(sum_{k=0}^infty A_k(t)varepsilon^kbigr)x+f(t), x(0,varepsilon)=x^0, can be transformed to the system with almost constant diagonal matrix dot z=Q(t,varepsilon)z+b(t,varepsilon). The result can be viewed as a constructive analogue of the Floquet-Lyapunov theorem. par Second, if delta=varepsilon^{-1} is a large parameter, the singularly perturbed system varepsilon dot x=(sum_{k=0}^infty A_k(t)varepsilon^k)+f(t), x(0,varepsilon)=x^0, is investigated and existence and uniqueness of a uniformly bounded solution on Bbb R^+ is proved for small varepsilon and an asymptotic formula of this solution is given