Interaction effects in assembly of magnetic nanoparticles

A specific absorption rate of a dilute assembly of various random clusters of iron oxide nanoparticles in alternating magnetic field has been calculated using Landau- Lifshitz stochastic equation. This approach simultaneously takes into account both the presence of thermal fluctuations of the nanoparticle magnetic moments, and magneto-dipole interaction between the nanoparticles of the clusters. It is shown that for usual 3D clusters the intensity of magneto- dipole interaction is determined mainly by the cluster packing density eta = Np*V/Vcl, where Np is the average number of the particles in the cluster, V is the nanoparticle volume, and Vcl is the cluster volume. The area of the low frequency hysteresis loop and the assembly specific absorption rate have been found to be considerably reduced when the packing density of the clusters increases in the range of 0.005 < eta < 0.4. The dependence of the specific absorption rate on the mean nanoparticle diameter is retained with increase of eta, but becomes less pronounced. For fractal clusters of nanoparticles, which arise in biological media, in addition to considerable reduction of the absorption rate, the absorption maximum is shifted to smaller particle diameters. It is found also that the specific absorption rate of fractal clusters increases appreciably with increase of the thickness of nonmagnetic shells at the nanoparticle surfaces.Comment: The paper is accepted for Nanoscale Res. Let

Networking in the food sector of regional economy

Purpose: The article aims to study the features and the directions of development of network interaction of subjects of the food sector in different regions of the economy. Design/Methodology/Approach: The use of different methodological approaches allowed us to formulate a holistic management concept for the development of a network of competences in the food sector of the regional economy. Findings: The study identified the subjects of such interaction, as well as features that allow them to unite into groups that form networks of competencies. Considering the food sector of the region's economy as a socio-economic system, noted its extreme structural complexity, which necessitates the development of special approaches to its management, or rather the need for structural management is presented. The format of such interaction is a network of competencies, representing a spatially localized socio-economic structure formed on the initiative of active subjects of the regional economy. Practical Implications: The results obtained can be used as a basis for designing a network form of development of the food sector of the region's economy, taking into account the nature of placement and interaction of participants, as well as allowing for effective use of their resource capabilities, experience and knowledge. Originality/Value: In order to overcome the problems associated with the formation of network identity, network management competence is proposed to use a structured approach allowing them to make targeted decisions based on objective conditions and institutional nature.peer-reviewe

CAPITALIZATION OF RELATIONS IN THE CONTEXT OF VALUE MANAGEMENT

The article deals with the capitalization of relations as a result of the interaction under conditions of value management. The author proves that, at the present time to obtain high results organizations form capital, contributing to sustainable socio-economic systems

MgB2 conductors for dc and ac applications

The paper presents discussion on up to date results on MgB2 conductors from the point of view of their future dc and ac applications. Basic physical parameters of MgB2 compound relevant to conductors are introduced. Different conductor preparation methods and conductor architectures are presented and attainable critical current densities discussed. Some numerical results on critical currents and ac losses of future multifilamentary MgB2 conductors with magnetic cladding of their filaments are given. Recently observed anomalous decrease of ac susceptibility at 50 K in copper clad Powder-in-tube, PIT, MgB2 wires is presented.Comment: Paper presented at EUCAS'01 conference, Copenhagen, 26-30 August 200