Dynamics of Switching Waves in a Nanofluid in a Light Field

The dynamics of the concentration of nanofluids placed in a light field with a Gaussian intensity profile is studied theoretically. The investigation is based on the analytical and numerical solutions of the system of linearized heat conduction and convectiondiffusion equations. The convection-diffusion equation contains terms that correspond both to the Soret effect and to the transfer of nanoparticles, caused by the action of a light field on them (electrostriction). The dependence of the coefficient of thermal conductivity of the medium on the concentration is taken into account. It is shown that under these conditions single travelling waves appear in the medium, the velocity of which depends not only on the thermal physical parameters of the medium, but also on the polarization of the particles. Conditions under which the stratification of the medium is possible are found

Temperature-dependent quantum electron transport in 2D point contact

We consider a transmission of electrons through a two-dimensional ballistic point contact in the low-conductance regime below the 0.7-anomaly. The scattering of electrons by Friedel oscillations of charge density results in a contribution to the conductance proportional to the temperature. The sign of this linear term depends on the range of the electron-electron interaction and appears to be negative for the relevant experimental parameters.Comment: 10 pages, 5 figure

Стадії гальваностатичного фазоутворення цинку на вольфрамовому електроді із цинкатного розчину

On the basis of the classical theory of galvanostatic nucleation and Vetter’s kinetic conception, formation of zinc nuclei on the tungsten electrode from the zincate electrolyte (0.5 М ZnO, 6 M NaOH) has been investigated. In the region of the current density 200 - 600 mАсm-2 the charge transfer overpotential (100 - 200 mV), the crystallization overpotential (50 - 60 mV), the nucleation work ((2 - 12)×10-20 J), the number of atoms in the nuclei (2 - 10) were determined. It was proved that nucleation take place on reduced sites of the oxidized tungsten surface. Within the range of studied diapason of current densities nucleis are forming on energetically similar electrode centers. The low value of the charge transfer coefficient (α = 0.26) indicates a weak effect of the double layer electrical field on the activation energy of charge transfer.      На основании классической теории гальваностатического фазообразования и кинетической концепции Феттера исследовано фазообразование цинка на вольфрамовом электроде из цинкатного раствора (0.5 М ZnO, 6 M NaOH). В области плотности тока 200-600 мА/см2 определено: перенапряжение перехода (100-200 мВ), перенапряжение кристаллизации (50-60 мВ), работа фазообразования ((2-12) ×10-20 Дж), число атомов в зародыше (2-10). Обосновано предположение, что фазообразование осуществляется на восстановленных участках окисленной поверхности вольфрама. В изученном диапазоне плотности тока зародыши формируются на энергетически однородных центрах электрода. Низкое значение коэффициента переноса (α = 0.26) отражает слабое влияние электрического поля двойного слоя на энергию активации переноса заряда.                На підставі класичної теорії гальваностатичного фазоутворення і кінетичної концепції Феттер досліджено фазоутворення цинку на вольфрамовому електроді з цинкатного розчину (0.5 М ZnO, 6 М NaOH). В області густини струму 200-600 мА/см2 визначено: перенапругу переходу (100-200 мВ), перенапругу кристалізації (50-60 мВ), роботу фазоутворення ((2-12) × 10-20 Дж), кількість атомів у зародку (2-10). Обґрунтовано припущення, що фазоутворення здійснюється на відновлених ділянках окисленої поверхні вольфраму. У вивченому діапазоні густини струму зародки формуються на енергетично однорідних центрах електрода. Низьке значення коефіцієнта переносу (α = 0.26) відображає слабкий вплив електричного поля подвійного шару на енергію активації переносу заряду.    

Transformation of polarons into magnetopolarons in GaAs quantum well

An experimental study is made of electron tunneling in a resonant-tunneling diode in magnetic fields directed parallel and perpendicular to the planes of the GaAs/Al xGa1-XAs heterostructure layers. In particular, phonon replicas on the current–voltage characteristics of the diode are investigated. In the second current derivatives a fine structure of replicas is found. The transformation of the structure of replicas in a perpendicular magnetic field can be qualitatively understood as a manifestation of the transition of polaron states to magnetopolaronic ones

The stages of galvanostatic nucleation of zinc on the tungsten electrode from a zincate solution

On the basis of the classical theory of galvanostatic nucleation and Vetter’s kinetic conception, formation of zinc nuclei on the tungsten electrode from the zincate electrolyte (0.5 М ZnO, 6 M NaOH) has been investigated. In the region of the current density 200 - 600 mАсm-2 the charge transfer overpotential (100 - 200 mV), the crystallization overpotential (50 - 60 mV), the nucleation work ((2 - 12)×10-20 J), the number of atoms in the nuclei (2 - 10) were determined. It was proved that nucleation take place on reduced sites of the oxidized tungsten surface. Within the range of studied diapason of current densities nucleis are forming on energetically similar electrode centers. The low value of the charge transfer coefficient (α = 0.26) indicates a weak effect of the double layer electrical field on the activation energy of charge transfer.      </div