Morphologies of copper deposits obtained at overpotentials belonging to the plateau of the limiting diffusion current density and at higher overpotentials were examined by the scanning electron ...microscopy (SEM) technique. Copper dendrites are formed at overpotentials belonging to the plateau of the limiting diffusion current density. The shape of copper dendrites depends on the electrodeposition overpotential. At higher overpotentials (800 and 1000 mV) and larger values of current densities, porous and very disperse copper deposits were obtained. These morphologies were a consequence of a very vigorous hydrogen evolution at these electrodeposition overpotentials. Also, the obtained copper structures consisted of agglomerates of copper grains. The size of copper grains is a function of the overpotential of electrodeposition, thus approaching to nano-sized dimensions is achieved when the electrodeposition overpotential is increased.
Copper electrodeposition from acid sulfate solutions at an overpotential of 1000
mV, which is about 250
mV outside the plateau of the limiting diffusion current density, was examined by the ...determination of the average current efficiency of hydrogen evolution and by the scanning electron microscopic (SEM) analysis of the morphology of the formed copper deposits. Craters or holes formed due to the attachment hydrogen bubbles were the dominant morphological forms of copper deposits obtained at this overpotential. In dependence of the concentration of Cu (II) ions in the plating solution, the two types of holes or craters were formed. One type of holes is obtained by electrodeposition from a solution with a concentration of Cu (II) ions of 0.075
M CuSO
4 in 0.50
M H
2SO
4, and a honeycomb-like structure was formed from these holes. The other types of holes are formed from a solution with a higher concentration of Cu (II) ions (0.60
M CuSO
4 in 0.50
M H
2SO
4) and the formed holes were dish-like. A mixture of both types of holes was obtained by electrodeposition from 0.30
M CuSO
4 in 0.50
M H
2SO
4. The obtained morphologies of copper deposits are discussed in terms of the effect of hydrogen evolution on the hydrodynamic conditions in the plating solution.
We show theoretically that entangled photon pairs can be produced on demand through the biexciton decay of a quantum dot strongly coupled to the modes of a photonic crystal. The strong coupling ...allows us to tune the energy of the mixed exciton-photon (polariton) eigenmodes and to overcome the natural splitting existing between the exciton states coupled with different linear polarizations of light. Polariton states are moreover well protected against dephasing due to their lifetime of ten to a hundred times shorter than that of a bare exciton. Our analysis shows that the scheme proposed is achievable with the present technology.
The reproducibility of research using laboratory animals requires reliable management of their quality, in particular of their genetics, health and environment, all of which contribute to their ...phenotypes. The point at which these biological materials are transferred between researchers is particularly sensitive, as it may result in a loss of integrity of the animals and/or their documentation. Here, we describe the various aspects of laboratory animal quality that should be confirmed when sharing rodent research models. We also discuss how repositories of biological materials support the scientific community to ensure the continuity of the quality of laboratory animals. Both the concept of quality and the role of repositories themselves extend to all exchanges of biological materials and all networks that support the sharing of these reagents.
Using Keldysh-Green function formalism we theoretically analyzed the dynamics of multimode exciton-polariton Josephson junctions. We took into account the spinor nature of polaritons and considered ...in detail the role of coupling of the fundamental modes with excited states. We demonstrate that the coupling to the reservoir results in a change of the oscillation pattern. In particular, it can lead to renormalization of the oscillation frequency, appearance of higher order harmonics, and induce transition between the regimes of free Josephson oscillations and macroscopic quantum self-trapping.
We propose a novel spin-optronic device based on the interference of polaritonic waves traveling in opposite directions and gaining topological Berry phase. It is governed by the ratio of the TE-TM ...and Zeeman splittings, which can be used to control the output intensity. Because of the peculiar orientation of the TE-TM effective magnetic field for polaritons, there is no analogue of the Aharonov-Casher phase shift existing for electrons.
Formation of irregular deposits by electrodeposition from acid sulfate solutions of various H
2SO
4 concentrations was examined by the determination of the average current efficiency of hydrogen ...evolution and by the scanning electron microscopic (SEM) analysis of the copper deposits morphology. Copper dendrites were the dominant morphological form obtained at overpotentials corresponding to the plateaus of the limiting diffusion current density. The number of the formed dendrites was increasing with the decreasing H
2SO
4 concentration. Holes formed due to the attached hydrogen bubbles were the basic morphological form of electrodeposited copper from all analyzed copper sulfate solutions at overpotentials outside the plateau of the limiting diffusion current density. The honeycomb-like structures (holes of the detached hydrogen bubbles with cauliflower-like agglomerates of copper grains between them) were formed if electrodepositions were performed from 0.15
M CuSO
4 in both 0.250
M and 1.0
M H
2SO
4. On the other hand, aside from the holes and cauliflower-like forms, electrodeposition from 0.15
M CuSO
4 in 0.125
M H
2SO
4 led to the formation of degenerated dendrites and dendritic particles inside channels formed of evolved hydrogen. Holes with shoulders of degenerated dendrites were also formed. The formation of different morphological forms under hydrogen co-deposition was discussed in the terms of hydrodynamic conditions in the near-electrode layer using the values for the break-off diameter of hydrogen bubbles.
Electrodeposition of copper from acid sulfate solutions at overpotentials on theplateau of the limiting diffusion current density and at higher overpotentials wasexamined. The average current ...efficiencies for hydrogen evolution reaction aredetermined by a measurement of the quantity of evolved hydrogen and the overallelectrodeposition current as a function of electrodeposition time, while morphologies ofcopper deposits are examined by the use of the scanning electron microscopy (SEM)technique. It is found that the open and porous structures of copper deposits (denoted andas honeycomb – like copper structures), suitable for electrodes in electrochemical devicessuch as fuel cells and chemical sensors, were reached by electrodeposition processesfrom solutions with the lower concentrations of Cu (II) ions (0.15 M CuSO4 and less in0.50 M H2SO4) at overpotentials outside the plateau of the limiting diffusion currentdensity at which the quantity of evolved hydrogen was enough to change hydrodynamicconditions in the near – electrode layer. The main characteristics of these copperstructures were craters or holes formed primarily due to the attachment hydrogen bubbleswith agglomerates of copper grains between them.
The morphologies of copper dendritic forms obtained in both potentiostatic and galvanostatic regimes of electrolysis with various amounts of the electricity were analyzed by the scanning electron ...microscopy (SEM) technique. Irrespective of amount of passed electricity, 3D (three dimensional) pine-like dendrites with sharp tips were formed in the potentiostatic regime of electrolysis. On the other hand, the amount of passed electricity had a strong effect on the shape of the 3D pine-like dendrites formed in the galvanostatic regime of electrolysis. Dendrites with sharp tips were formed with smaller amount of passed electricity, while dendrites with globular tips were formed with larger amounts. The change in the shape of the galvanostatically synthesized 3D pine-like dendrites was explained by comparison with copper deposits obtained potentiostatically at overpotentials that corresponded to the final overpotentials during galvanostatic regime of electrolysis for the analyzed amounts of electricity. Based on the similarity of the obtained morphologies at the macro level, it was concluded that the overpotential plays a crucial role in the formation of the electrolytically synthesized dendrites and that the controlled conditions of electrolysis could represent a suitable way for a synthesis of spherical Cu particles by electrolysis.
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