Adsorption transition of a grafted ferromagnetic filament controlled by external magnetic fields

[eng] Extensive Langevin dynamics simulations are used to characterize the adsorption transition of a flexible magnetic filament grafted onto an attractive planar surface. Our results identify different structural transitions at different ratios of the thermal energy to the surface attraction strength: filament straightening, adsorption, and the magnetic flux closure. The adsorption temperature of a magnetic filament is found to be higher in comparison to an equivalent nonmagnetic chain. The adsorption has been also investigated under the application of a static homogeneous external magnetic field. We found that the strength and the orientation of the field can be used to control the adsorption process, providing a precise switching mechanism. Interestingly, we have observed that the characteristic field strength and tilt angle at the adsorption point are related by a simple power law

Self-organization in dipolar cube fluids constrained by competing anisotropies

For magnetite spherical nanoparticles, the orientation of the dipole moment in the crystal does not affect the morphology of either zero field or field induced structures. For non-spherical particles however, an interplay between particle shape and direction of the magnetic moment can give rise to unusual behaviors, in particular when the moment is not aligned along a particle symmetry axis. Here we disclose for the first time the unique magnetic properties of hematite cubic particles and show the exact orientation of the cubes' dipole moment. Using a combination of experiments and computer simulations, we show that dipolar hematite cubes self-organize into dipolar chains with morphologies remarkably different from those of spheres, and demonstrate that the emergence of these structures is driven by competing anisotropic interactions caused by the particles' shape anisotropy and their fixed dipole moment. Furthermore, we have analytically identified a specific interplay between energy, and entropy at the microscopic level and found that an unorthodox entropic contribution mediates the organization of particles into the kinked nature of the dipolar chains

A REPRESENTATIVE SOLUTION TO M-ORDER LINEAR ORDINARY DIFFERENTIAL EQUATION WITH NONLOCAL CONDITIONS BY GREEN'S FUNCTIONAL CONCEPT

In this work, we investigate a linear completely nonhomogeneous nonlocal multipoint problem for an m-order ordinary differential equation with generally variable nonsmooth coefficients satisfying some general properties such as p-integrability and boundedness. A system of m + 1 integro-algebraic equations called the special adjoint system is constructed for this problem. Green's functional is a solution of this special adjoint system. Its first component corresponds to Green's function for the problem. The other components correspond to the unit effects of the conditions. A solution to the problem is an integral representation which is based on using this new Green's functional. Some illustrative implementations and comparisons are provided with some known results in order to demonstrate the advantages of the proposed approach

From the History of Russian Computer Science

International audienceThis article includes a few passages from the History of Computer Science relating to the events of the middle of the last century. The first part of this article contains a short biography of Norbert Wiener, who is considered to be one of the fathers of modern computer science. This part pays particular attention to Norbert Wiener’s visit to Moscow in the summer of 1960. The other parts of the article focus on life and work of Aleksey Lyapunov, Leonid Kantorovich and Andrey Ershov. The outstanding professional achievements of these Russian scientists, as well as their moral perfection, can set an example for modern students and young professionals