Immobilization of Analgetic AB-101 into Calcium Alginate Gels

A new analgetic drug AB-101 has been immobilized into Ca2+-alginate gel beads with average diameter of 1 mm. A series of the alginate gel contains with various mannuronic/guluronic (M/G) ratios has been chosen to control the diffusion of the drug. Release of the drug from the alginate gel beads into physiological solutions consisting of sodium ions has been examined. A discontinuous time of the Fickian diffusion of the drug depending on M/G ratio was followed by a burst release of the remaining drugs. The burst release was due to a swift disintegration of Ca2+-alginate with exchange on sodium ions. The preceding discontinuous lag time promotes a free dissociate exchange of sodium-calcium ions in M units, while the burst disintegration leads to fast dissociation of G units. The lag time can be control by M/G ratio of Ca2+-alginate gels. The lag time increases if a content of the M units decreases. The increase of M units was led to more extensive swelling of the gel beads. Such way could be promising for a controlled drug delivery or the use in implants with controlled drug effect

Current status of turbulent dynamo theory: From large-scale to small-scale dynamos

Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic Prandtl numbers. It is argued that all the different cases show similarities at intermediate length scales. On the other hand, in the presence of helicity of the turbulence, power develops on large scales, which is not present in non-helical small-scale turbulent dynamos. At small length scales, differences occur in connection with the dissipation cutoff scales associated with the respective value of the magnetic Prandtl number. These differences are found to be independent of whether or not there is large-scale dynamo action. However, large-scale dynamos in homogeneous systems are shown to suffer from resistive slow-down even at intermediate length scales. The results from simulations are connected to mean field theory and its applications. Recent work on helicity fluxes to alleviate large-scale dynamo quenching, shear dynamos, nonlocal effects and magnetic structures from strong density stratification are highlighted. Several insights which arise from analytic considerations of small-scale dynamos are discussed.Comment: 36 pages, 11 figures, Spa. Sci. Rev., submitted to the special issue "Magnetism in the Universe" (ed. A. Balogh