Rotation of a dynamically symmetric body under constant and dissipative torques

Conclusion With the help of the variables k₁ and k₂ we have found quasistationary regimes of axial rotation and have determined their characteristics. For the general case (a>0, b>0, c>0, c<0) the quasistationary axial rotation k₂=k*₂ is asymptotically stable with respect to k₂. Similar regimes but with different values of k*₂ occur when one of the components of the dissipative torque vanishes (a=0, b>0, c>0, c<0 or a>0, b=0 c>0, c<0). Under the quadratic component of the torque (b=c=0, a>0) the axial rotation of the body is determined by the sign of the initial value of k₂. The behavior of the rotation of the body for only the dissipative torque (a>0, b>0, c=0) or only its linear component (a=c=0, b>0) depends on the ratio of the coefficients and b of the linear dissipation and can lead to axial rotation or to rotation in the equatorial plane. It follows from the above diagrams that axial rotation of a body in a medium with weak drag can be stabilized by applying a small constant torque about the axis of dynamical symmetry.Moscow. Translated from Prikladnaya Mekhanika, Vol. 29, No. 3, pp. 82–85, March, 1993.     

Study of the physicochemical characteristics of dispersions of n-alkanes C23H48 and C28H58 in water: zeta potential and temperatures of phase transitions

The effect of pH on the zeta potential of dispersions of individual n-alkanes C₂₃H₄₈ and C₂₈H₅₈ with particle sizes of the order of 100 nm, which were prepared by ultrasonic dispersion without the addition of surfactants, was studied. It is shown that at pH ranged from 4 to 12, the investigated n-alkanes form stable dispersions in water. They are characterized by a high zeta potential varying from ?30 to ?50 mV. The phase transition temperatures (melting point, crystallization temperature, formation of rotator phases) were determined for the dispersions using an optical method.

     

Phase behavior of DODAB aqueous solution

Phase behavior of DODAB aqueous solution, prepared without sonication, was studied by adiabatic scanning calorimetry. Measurements revealed four phase transitions with the temperatures 35.2, 39.6, 44.6, and 52.4°C at heating and one transition at the temperature 40.4°C at cooling. The first three transitions at heating occur in unilamellar vesicles. The first and third transitions correspond to the subgel-gel and gelliquid phase transitions, corresponding enthalpy jumps are equal to 33 and 49 kJ/mol. The second transition appears after some aging and is similar to gel-ripple phase transition in a DPPC solution, with the enthalpy jump under the transition exceeding 7.4 kJ/mol. The transition occurs in unilamellar vesicles. The transition at the temperature 52.4°C occurs in another subsystem of the solution, which we believe to be multilamellar vesicles. The enthalpy jump at this transition is equal to 97 kJ/mol, and data analysis suggests that this is a subgel-liquid transition. The phase transition at cooling is the liquid-gel transition in unilamellar vesicles. During the measurements, a slow evolution of the solution occurs, consisting in a change of concentrations of unilamellar and multilamellar vesicles. This transformation mainly occurs at low temperatures.     

Impact of silver nanoparticles synthesized by green method and microemulsion loaded with the nanoparticles on the development of cress

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Comparison of micro-DSC and light scattering methods for studying the phase behavior of n-alkane in the oil-in-water dispersion

Journal of Thermal Analysis and Calorimetry - This article investigates the phase behavior of&nbsp;n-octacosane (C28H58) in the form of an aqueous dispersion with a particle size of about...