The formation of amorphous metal nanoparticles by the method of electrohydrodynamic dispersion is studied. In this method, fine liquid metal drops are generated, charged in an electron beam to an ...unstable state, and dispersed into nanometer droplets. Rapid cooling of these nanometer droplets results in the formation of amorphous metal nanoparticles. The chief problem in the formation of such particles is that it is difficult to charge molten metal drops to an unstable state, since the bombardment of the drop by an electron beam may cause intense emission of electrons. To overcome this difficulty, the drops are charged by a beam of slow electrons. Charging proceeds in such a way that the electron energy rises with the drop’s charge. It is shown that this method makes it possible to obtain granulated films made up of amorphous metal particles. Copper films with a nanoparticle mean size of 2 nm and a small dimensional variation are prepared.
We discuss the importance of the vortex core energy and realistic boundary conditions to the Fokker-Plank equation for the calculation of thermally activated hopping of vortices across narrow ...superconducting films. Disregard of these issues in the papers by Bulaevskii, Graf and Kogan, Phys. Rev. B 85, 014505 (2012) (http://dx.doi.org/10.1103/PhysRevB.85.014505) and by Bulaevskii et al., Phys. Rev. B 83, 144526 (2011) (http://dx.doi.org/10.1103/PhysRevB.83.144526) in which an uncertain London vortex core cutoff was used, can produce large numerical errors and a significant discrepancy between their results and the results of the paper by Gurevich and Vinokur, Phys. Rev. Lett. 100, 227007 (2008) (http://dx.doi.org/10.1103/PhysRevLett.100.227007) in which these issues were taken into account. This can be essential for the interpretation of experimental data on thin-film photon detectors and other superconducting nanostructures.
This lengthy review is devoted to large-scale electric fields in the Earth's magnetosphere. Such fields play an important part in the dynamics of the magnetosphere and the ionosphere. They determine ...the convection in the magnetosphere, drifts and currents in the ionosphere, variations of the geomagnetic field, and the stability and inhomogeneous structure of the magnetosphere and ionosphere. The following list of topics is covered in considerable detail: the electric field potential; conductivity of the ionosphere and magnetosphere; electric currents; magnetic field disturbances; plasma convection (electric field of rotation); electric field in the low latitude ionosphere; and electric fields and currents in the high latitude ionosphere. A mathematical appendix is included.
The process of lithium insertion into thin gold films is studied. It is found that lithium is reversibly inserted with the formation of compounds, which are close to Li
1.5
Au in their average ...composition. The long-term cycling leads to the breakdown of gold layer (and corresponding decrease in the electrode capacity), which is associated with considerable volume changes due to lithium insertion.
An overview of the theory of the upper critical field in dirty two-gap
superconductors, with a particular emphasis on MgB$_2$ is given. We focus here
on the maximum $H_{c2}$ which may be achieved by ...increasing intraband
scattering, and on the limitations imposed by weak interband scattering and
paramagnetic effects. In particular, we discuss recent experiments which have
recently demonstrated ten-fold increase of $H_{c2}$ in dirty carbon-doped films
as compared to single crystals, so that the $H_{c2}(0)$ parallel to the ab
planes may approach the BCS paramagnetic limit, $H_pT = 1.84T_cK \simeq
60-70T$. New effects produced by weak interband scattering in the two-gap
Ginzburg-Landau equations and $H_{c2}(T)$ in ultrathin MgB$_2$ films are
addressed.
The Escherichia coli genes encoding purine nucleoside phosphorylase, uridine phosphorylase, and thymidine phosphorylase were cloned into pET plasmids to generate highly effective E. coli BL21(DE3) ...strains producing each of these enzymes. Optimum conditions for biosynthesis of each enzyme as a soluble protein with intact biological activity were found. The crude preparations are approximately 80% pure and can be used immediately for enzymatic transglycosylation. The enzyme preparations were purified to homogeneity by two steps including fractional precipitation with ammonium sulfate and subsequent chromatography on Sephadex G-100 and DEAE-Sephacel.
