MOVEMENT OF CHARGED PARTICLES IN MAGNETIC AND NONUNIFORM STOCHASTIC ELECTRIC FIELDS

The equation of motion of charged plasma particles in a homogeneous magnetic field and in an inhomogeneous stochastic electric field with a characteristic oscillation frequency much lower than the electron cyclotron frequency and much higher than the ion cyclotron frequency is solved. The diffusion motion, as well as the drift of ions and guiding center of electrons, due to the inhomogeneity of the stochastic electric field, is considered. The obtained values of the diffusion coefficient and drift velocity are used in the Fokker-Planck equation to determine the stationary distribution of the plasma density due to the effect of an inhomogeneous stochastic field.

Modeling of diffusion motion of In nanoparticles in a CdTe crystal during laser-induced doping

In order to solve the problem of the ohmic contact between the crystal surface and the metal electrode in the manufacturing process of the X/γ-ray detector, this paper uses a laser to probe the doping process of In/CdTe crystals in different media. In this experiment, the Traveling Heater Method (THM) is used to obtain CdTe(111) crystals that meet the requirements (ρ >109Ω∙cm). In and Au materials are respectively coated on the surface of the crystal sample by the vacuum thermal evaporation method to obtain the crystal sample meeting the requirements. The high-resistance p-type CdTe crystal of a relatively thick In film is irradiated with nanosecond laser pulses, the In film is used as an n-type doping source and as an electrode after laser irradiation.

Calcium-vesicles perform active diffusion in the sea urchin embryo during larval biomineralization

Biomineralization is the process by which organisms use minerals to harden their tissues and provide them with physical support. Biomineralizing cells concentrate the mineral in vesicles that they secret into a dedicated compartment where crystallization occurs. The dynamics of vesicle motion and the molecular mechanisms that control it, are not well understood. Sea urchin larval skeletogenesis provides an excellent platform for investigating the kinetics of mineral-bearing vesicles. Here we used lattice light-sheet microscopy to study the three-dimensional (3D) dynamics of calcium-bearing vesicles in the cells of normal sea urchin embryos and of embryos where skeletogenesis is blocked through the inhibition of Vascular Endothelial Growth Factor Receptor (VEGFR). We developed computational tools for displaying 3D-volumetric movies and for automatically quantifying vesicle dynamics. Our findings imply that calcium vesicles perform an active diffusion motion in both, calcifying (skeletogenic) and non-calcifying (ectodermal) cells of the embryo. The diffusion coefficient and vesicle speed are larger in the mesenchymal skeletogenic cells compared to the epithelial ectodermal cells. These differences are possibly due to the distinct mechanical properties of the two tissues, demonstrated by the enhanced f-actin accumulation and myosinII activity in the ectodermal cells compared to the skeletogenic cells. Vesicle motion is not directed toward the biomineralization compartment, but the vesicles slow down when they approach it, and probably bind for mineral deposition. VEGFR inhibition leads to an increase of vesicle volume but hardly changes vesicle kinetics and doesn’t affect f-actin accumulation and myosinII activity. Thus, calcium vesicles perform an active diffusion motion in the cell of the sea urchin embryo, with diffusion length and speed that inversely correlate with the strength of the actomyosin network. Overall, our studies provide an unprecedented view of calcium vesicle 3D-dynamics and point toward cytoskeleton remodeling as an important effector of the motion of mineral-bearing vesicles.

Photothermoelectric resistance effect observed in Ti/SiO2/Si structure induced by 10.6 μm CO2 laser

A novel photothermoelectric resistance effect of the Ti/SiO2/Si films induced by 10.6 [Formula: see text]m CO2 laser is discovered and investigated. The transient response of the resistance is observed and analyzed in this work. Under the continuous irradiation of the laser, the thermal resistance value changes with the irradiating time and gradually reaches a stable saturation. The results indicate that the rise time of thermal resistance is shortened and its change rate increased as laser power gets higher. The inner battery of the ohmmeter exerts the positive or negative bias voltage, causing the diffusion motion direction of the hot electrons to be opposite or the same direction with the drift motion, which can increase or decrease the thermal resistance value. Those experimental phenomena are explained by the drift and diffusion motion of the electrons. Based on the results, the Ti/SiO2/Si structure is an attractive candidate for thermal effect devices.

Simulation of diffusion motion of ionomers using Monte Carlo algorithm

We present a simple model of ionomers, namely a single polymer chain in a series of fixed attractors. In analogy to ionized bead’s claws of surrounding chains, the set of attractors can affectively slow down the diffusion motion of the target chain. The monomer mean-square displacement of ionomers is studied by using Monte Carlo algorithm, and compared with the prediction of the sticky Rouse model. The diffusion motion properties of ionomers are explored in three aspects, including the chain length of the polymer, the depth of the potential well and the number of ionic groups. The results show that a plateau appears in the monomer diffusion function due to the attraction of the attractors to the claws. However, comparative theoretical predictions and simulation results show that there exists some discrepancy between them. Therefore, the relaxation time distribution of polymer chain motion is explored. The simulation results confirm that the association lifetime is decreasing exponentially, and the expected values of the association lifetime satisfy the Boltzmann distribution as shown by the results. These results perfectly explain the deviation between the simulation data and the theoretical results.