The magnetic properties and hyperthermia effect were studied in a magnetorheological fluid (MRF) containing iron particles of 1µm to 5 µm in diameter. The measurements showed that the magnetization in the saturation state reaches a value of 171 A · m 2 · kg −1 with very small values of coercivity and remanence. They also showed the ferromagnetic behavior in the system together with a value of the magnetic susceptibility of 1.7. Theoretical and experimental results of the calorimetric effect investigation under a changeable magnetic field of high frequency ( f = 504 kHz) in an MRF will be presented in the article. The sample was subjected to an alternating magnetic field of different strengths (H = 0 to 4 kA · m −1 ). It results from a theoretical analysis that the heat power density (released in the MRF sample) referenced to the eddy current is proportional to the square of frequency, the magnetic field amplitude, and the iron grain diameter. Experimental results indicate that there are some reasons for the released heat energy such as: energy losses from magnetic hysteresis and eddy currents induced in the iron grains. If the magnetic field intensity amplitude grows, the participation of losses connected with magnetic hysteresis is increased. From the calorimetric measurements, the conclusion is as follows: for a magnetic field H < 1946 A · m −1 , the eddy current processes dominate in the heat generation mechanism, whereas hysteresis processes for the total release of thermal energy dominate for higher magnetic fields. Both mechanisms take equal parts in heating the tested sample at a magnetic field intensity amplitude H = 1946 A · m −1 . The specific absorption rate referenced to the mass unit of the MRF sample at the amplitude of the magnetic field strength 4 kA · m −1 equals 24.94 W · kg −1 at a frequency f = 504 kHz.

Manipulation of particles at the surface of a droplet can lead to the formation of structures with heterogeneous surfaces, including patchy colloidal capsules or patchy particles. Here, we study the assembly and rearrangement of microparticles confined at the surface of oil droplets. These processes are driven by electric-field-induced hydrodynamic flows and by ‘electro-shaking’ the colloidal particles. We also investigate the motion of an intruder particle in the particle film and present the possibility of segregating the surface particles. The results are expected to be relevant for understanding the mechanism for particle segregation and, eventually, lead to the formation of new patchy structures.

We report experimental results for the melting of eutectic mixtures confined in nanoporous matrices. Dielectric relaxation spectroscopy and differential scanning calorimetry were used to determine the solid/liquid phase diagram of C6H4Br2/CCl4 mixtures confined in controlled pore glasses (CPG) with an average pore diameter of 7.5 nm, and C6H5Br/CCl4 mixtures confined in activated carbon fibers (ACF) with a mean pore diameter of 1.4 nm. We find that the phase diagram of the confined mixtures are of the same type as that for the bulk mixture (eutectic). However, in the case of mixtures in carbon nanopores the solid/liquid coexistence lines are located at higher temperatures than for the bulk mixtures, whereas they are at lower temperatures than the bulk for mixtures confined in silica pores. These results are compared with those previously obtained for azeotropic mixtures in ACF. The results suggest that the melting temperatures, T mp, of confined mixtures decrease relative to the bulk when the fluid–wall interactions are weaker than the fluid–fluid interaction (silica glasses), and increase in the case of fluid–wall interactions that are stronger than the fluid–fluid interaction (nanoporous carbons).

Magnetic Co-beads were fabricated in the course of a three-step procedure comprising preparation of a metal-acrylamide complex, followed by frontal polymerization and finally pyrolysis of the polymer. The composites obtained were composed of cobalt nanocrystallites stabilized in a carbon matrix built of disordered graphite. The crystallite size, material morphology, fraction of the magnetic component, and thus the magnetic properties can be tailored by a proper choice of the processing variables. The samples were subjected to an alternating magnetic field of different strengths (H = 0 to 5 kA · m −1 ) at a frequency of f = 500 kHz. From the calorimetric measurements, we concluded that the relaxation processes dominate in the heat generation mechanism for the beads pyrolyzed at 773 K. For the beads pyrolyzed at 1073 K, significant values of magnetic properties, such as the coercive force and remanence give substantial contribution to the energy losses for hysteresis. The specific absorption coefficient (SAR) related to the cobalt mass unit for the 1073 K pyrolyzed beads (SAR = 1340 W · g −1 cobalt ) is in very good conformity with the results obtained by other authors. The effective density power loss, caused by eddy currents, can be neglected for heating processes applied in magnetic hyperthermia. The Co-beads can potentially be applied for hyperthermia treatment.

The paper reports the study of the complexation processes in aqueous solution of α-CD and DMSO. Cyclodextrins (CDs) (sometimes called cycloamyloses) are cyclic oligosaccharides formed by glucose units interconnected by α-(1,4) linkages; α-CD is one of three the most common CDs. It consists of six glucopyranose units. The speed of ultrasonic waves has been measured by the resonance method on Resoscan TM System apparatus. Some collateral data, such as density and heat capacity of the system, have also been measured. On the basis of the experimental data the excess adiabatic compressibility was determined. The extremes of the excess adiabatic compressibility function for different mixture compositions allowed us to establish the composition of molecular complexes formed in the solution. The obtained results suggest the formation of the α-CD with DMSO inclusion complexes with chemical stoichiometric ratio value of 1:1.