[en] A method is described for measuring the magnetorheological characteristics of ferrosuspensions by means of a capillary rheometer by use of measurement section in the form of a helix. This configuration permits liberal variation of the fundamental technical characteristics (diameter and length of the capillary) while imparting overall dimensions to the measurement section such that practical homogeneous magnetic field patterns can be utilized. It is noted that because of the orientation effect, the viscosity of the ferrosuspension in the inlet and exit ducts will be much smaller than the viscosity in the working section, thereby enhancing the measurement accuracy and simplifying the measurement of the pressure differential. Principal measurement errors associated with the proposed experimental scheme are analyzed. 6 references

[en] Recent results on the behaviour of aluminium and zinc superconducting grain colloids at very low temperature are reported, exhibiting possible evidence for avalanche phenomena. (orig.)

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[en] The structure of colloidal crystals, determined by scattering methods, is discussed. Charge-stabilized particles are considered briefly. The phase behaviour and crystal structures of 'hard-sphere' sterically-stabilized particles are described in more detail. Both one-component suspensions and binary mixtures of different-sized spheres are considered. (author). 9 refs.; 2 figs

[en] Previous computation of stability factors of colloidal gold from coagulation data was found to be in systematic error due to an underestimation of the particle concentration by electron microscopy. A new experimental technique was developed for determination of this concentration. Stability factors were recalculated from the previous data using the correct concentration. While most of the previously reported conclusions remain unchanged, the absolute rate of fast coagulation is found to agree with that predicted by the theory. A value of the Hamaker constant was determined from the corrected data

No abstract available

[en] The spectral luminescent characteristics of colloidal quantum dots as a new class of luminophores are discussed and state-of-the-art investigations, problems, and prospects for their applications are considered. (conferences and symposia)

[en] In this work an alternative method has been developed which permits to estimate the rate constant of an aggregation process of model colloids (spheric and monodisperse particles) but in an automatic and reliable way, because a longer time is considered during the aggregation process which avoid the uncertainties for the calculation of the initial slopes with very few experimental data. to reach an objective condition a limit time of 20 s was taken and it is necessary to assume a concrete form of the aggregates growing which establishes a square dependency between the optical absorbance and the time. By this fitting it is possible to estimate the coagulation rate constant which is in accordance with that obtained by conventional methods, but now the rate constant is the same and maintains a constant value for a longer time (till 20 s). (Author) 19 refs

[en] We study the current rectification of particles moving in a pulsating channel under the influence of an applied force. We have shown the existence of different rectification scenarios in which entropic and energetic effects compete. The effect can be quantified by means of a rectification coefficient that is analyzed in terms of the force, the frequency and the diffusion coefficient. The energetic cost of the motion of the particles expressed in terms of the entropy production depends on the importance of the entropic contribution to the total force. Rectification is more important at low values of the applied force when entropic effects become dominant. In this regime, the entropy production is not invariant under reversal of the applied force. The phenomenon observed could be used to optimize transport in microfluidic devices or in biological channels. (paper)