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Multilayer structures on the basis of n-type (In,Fe)Sb and p-type (Ga,Fe)Sb diluted magnetic semiconductors (DMS) along with separate (In,Fe)Sb and (Ga,Fe)Sb layers were fabricated on GaAs substrates by pulsed laser sputtering of InSb, GaAs, GaSb, Sb and Fe targets in a vacuum. Transmission electron microscopy and energy-dispersive x-ray spectroscopy reveal a strong dependence of the phase composition of the (In,Fe)Sb compound on the growth temperature. An increase of the latter from 220 °C to 300 °C leads to a coalescence of Fe atoms and formation of a secondary crystalline phase in the (In,Fe)Sb layer with a total Fe content of ≈ 10 at. %. At the same time, the Ga0.8Fe0.2Sb layers obtained at 220 °C and 300 °C are single-phase. The separate In0.8Fe0.2Sb and Ga0.8Fe0.2Sb layers grown on i-GaAs at 220 °C are DMS with Curie temperatures of ≈ 190 K and 170 K, respectively. The three-layer p-i-n diode (In,Fe)Sb/GaAs/(Ga,Fe)Sb structure grown on a GaAs substrate at 220 °C with a Fe content of 10 ± 1 at. % in the single-phase (In,Fe)Sb and (Ga,Fe)Sb layers has a rather high crystalline quality and can be considered as a prototype of a bipolar spintronic device based on Fe-doped III-V semiconductors.

Reliable generation and measurement of triphoton states has yet to be achieved in laboratory. We give an overview of the problems in generating and measuring triphoton quantum states and analyze several protocols of quantum measurements, which allow for high precision of reconstruction when sizes of available statistical data samples are limited. The tomography procedure under investigation is based on root approach to state estimation. In particular, we use the generalized Fisher information matrix to assess the accuracy of the quantum state parameters measurement. We use tomographic protocols, based on the symmetry of the Platonic solids. We demonstrate the capability to reconstruct triphoton quantum states with precision close to the maximum achievable value allowed by quantum mechanics, 11 pages, 5 figures. International Conference on Micro- and Nano-Electronics 2016. Zvenigorod, Russian Federation, October 3-7, 2016

This article is about the trial of transplantation of fetal cells of pancreas to laboratory mice with streptosotozin diabetes. Cells were infused into liver in the dose of 105 cells/0,5 ml. Mices that received rabbit β-cells had normal level blood glucose within 2 months after xenotransplantation.

Recently, local bifurcation theory for delayed neural fields was developed. In this paper, we show how symmetry arguments and residue calculus can be used to simplify the computation of the spectrum in special cases and the evaluation of the normal form coefficients, respectively. This is done hand in hand with an extensive study of two pitchfork–Hopf bifurcations for a 1D neural field model with ‘Wizard hat’ type connectivity.

Bifurcation theory provides powerful tools for the analysis of the dynamics of open-loop or closed-loop nonlinear control systems. These systems are Filippov (or piecewise smooth) when the dynamics depends discontinuously on the state, for example as a consequence relay feedback actions. In this paper we contribute to the analysis of codimension-two bifurcations in Filippov systems by reporting some results on the equilibrium bifurcations of 2D systems that involve a sliding limit cycle. There are only two such local bifurcations: a degenerate boundary focus that we call homoclinic boundary focus ; and the boundary Hopf. We address both of them, and provide the complete set of curves that exist around such codimension-two bifurcation points. Existing numerical software can be used to exploit these results for the analysis of the stability boundaries of nonlinear piecewise smooth control systems. In the final part of this paper, we discuss a 2D Filippov system modelling an ecosystem subject to on-off harvesting control that exhibits both codimension-two bifurcations.

Particles of ΔProCANC, a fusion of capsid (CA) and nucleocapsid (NC) protein of Mason-Pfizer monkey virus (M-PMV), which lacks the amino terminal proline, were reassembled in vitro and visualized by atomic force microscopy (AFM). The particles, of 83-84 nm diameter, exhibited ordered domains based on trigonal arrays of prominent rings with center to center distances of 8.7 nm. Imperfect closure of the lattice on the spherical surface was affected by formation of discontinuities. The lattice is consistent only with plane group p3 where one molecule is shared between contiguous rings. There are no pentameric clusters nor evidence that the particles are icosahedral. Tubular structures were also reassembled, in vitro, from two HIV fusion proteins, ΔProCANC and CANC. The tubes were uniform in diameter, 40 nm, but varied in length to a maximum of 600 nm. They exhibited left handed helical symmetry based on a p6 hexagonal net. The organization of HIV fusion proteins in the tubes is significantly different than for the protein units in the particles of M-PMV ΔProCANC. © 2006 Elsevier Inc. All rights reserved.

Turnip Yellow Mosaic Virus (TYMV) was subjected to a variety of procedures which disrupted the protein capsids and produced exposure of the ssRNA genome. The results of the treatments were visualized by atomic force microscopy (AFM). Both in situ and ex situ freeze-thawing produced RNA emission, though at low efficiency. The RNA lost from such particles was evident, in some cases in the process of exiting the virions. More severe disruption of TYMV and extrusion of intact RNA onto the substrate were produced by drying the virus and rehydrating with neutral buffer. Similar products were also obtained by heating TYMV to 70 -75 °C and by exposure to alkaline pH. Experiments showed the nucleic acid to have an elaborate secondary structure distributed linearly along its length. © 2006 Elsevier Inc. All rights reserved.

A genetically engineered humanized CH2-domain-deleted monoclonal antibody lacking any interchain-hinge disulfide bonds has been crystallized in the presence of detergent in a form suitable for X-ray diffraction analysis. The crystals were grown from 4 M formate along with Triton X-100 and had P2 1212 space-group symmetry, with unit-cell parameters a = 83, b = 224, c = 167 Å. The crystals diffract to beyond 2.8 Å resolution. A disordered crystal form of larger size and more attractive habit was also grown from 4 M formate, but in the presence of the Anapoe series of detergents. Preliminary X-ray data, in conjunction with atomic force microscopy images, are consistent with asymmetric units consisting of two intact antibodies forming a circular dimeric ring. The crystallizing unit, which must contain a twofold axis, is a toroidal assembly of four antibodies (two dimeric rings). Competition between dimers and tetramers to enter the lattice, along with a unique kind of planar defect of packing, may be responsible for the unusually high defect density and the disorder of the X-ray diffraction pattern exhibited by the second crystal form. An approach to crystallizing proteins showing phase separation, particularly intact antibodies, that uses a preliminary detergent test set is described. © 2005 International Union of Crystallography - all rights reserved.

A virus PBCV-1, which infects certain fresh water algae and has been shown by transmission and cryo-electron microscopy to exist as a triskaidecahedron, was imaged using atomic force microscopy (AFM). From AFM the particles have diameters of about 190 nm and the overall structure is in all important respects consistent with existing models. The surface lattice of the virion is composed of trimeric capsid proteins distributed according to p3 symmetry to create a honeycomb arrangement of raised edges forming quasi-hexagonal cells. At the pentagonal vertices are five copies of a different protein forming an exact pentagon, and this has yet another unique protein in its center. The apical protein exhibits some unusual mechanical properties in that it can be made to retract into the virion interior when subjected to AFM tip pressure. When PBCV-1 virions degrade, they give rise to small, uniform, spherical, and virus like particles (VLP) consistent with T = 1 or 3 icosahedral products. Also observed upon disintegration are strands of linear dsDNA. Fibers of unknown function are also occasionally seen associated with some virions. © 2004 Elsevier Inc. All rights reserved.

The experimental results on the Alfvén mode structure identification by the microwave reflectometry in TCABR tokamak are presented. The knowledge of the spatial spectrum of the excited waves is crucial for optimization of Alfvén wave plasma heating and noninductive current drive scenarios in tokamak plasmas. No less important is the possibility to use the Alfvén wave excitation for diagnostic purposes. A microwave reflectometer with fixed frequency was used to register plasma density oscillations driven by the excited Alfvén waves, under the condition of the spectrum scanned by a controlled plasma density rise. It is shown that when the position of the local Alfvén resonance, rA, which is defined by relation omega = k||(rA)C A(rA), is close to the plasma zone where the microwave signal is reflected, the high-frequency modulation of the output signal of the reflectometer at the RF generator frequency increases. The possibility to use the observed effect for finding the plasma current profile in tokamaks is discussed.

"A new regime of runaway discharges has been observed in the TCABR tokamak. One of the most distinctive features of this regime is the effect of plasma detachment from the limiter. This experimental fact can only be explained by the volume recombination, which requires a low-temperature plasma. The analysis of the energy and particle balance in the system plasma-relativistic runaway beam in TCABR, which takes into account only the collisional mechanism of the heat transfer from runaways to thermal electrons, predicts electron temperatures Te = 0.1 - 2 eV; the temperature decreases with the neutral density increase. The recombination process with the rate constant around 10-16 m³/s is required for the explanation of plasma density behavior in the experiment. At present, it is difficult to conclude about the mechanism of recombination. More reliable and detailed experimental data, mainly about the plasma temperature, are necessary."

We consider numerical methods for the computation and continuation of the three generic secondary periodic solution bifurcations in autonomous ordinary differentialequations (ODEs), namely the fold, the period-doubling (or flip) bifurcation, and the torus (or Neimark-Sacker) bifur- cation. In the fold and flip cases we append one scalar equation to the standard periodic boundary value problem (BVP) that defines the periodic solution; in the torus case four scalar equations are appended. Evaluation of these scalar equations and their derivatives requires the solution of lin- ear BVPs, whose sparsity structure (after discretization) is identical to that of the linearization of the periodic BVP. Therefore the calculations can be done using existing numerical linear algebra techniques, such as those implemented in the software auto and colsys.

Atomic force microscopy was applied to investigate the influence of protein and precipitant (sodium-potassium tartrate) concentration on thaumatin crystal growth mechanisms. At constant protein concentration, a decrease of salt concentration from 0.8 to 0.085M caused a transition of the crystal growth mechanism from two-dimensional nucleation to dislocation growth. At different, fixed concentrations of salt, the protein concentration, which does not induce multiple crystal nucleation, was increased from 8 to 60mg/ml with corresponding increases in the tangential velocity of growth steps from 5 to 17.5nm/s. Results from these experiments suggest that a highly concentrated protein solution, as might be found in a protein rich phase, may not induce crystal nucleation, but can promote crystal growth if screw dislocations are present in the crystal. © 2001 Elsevier Science B.V. All rights reserved.

In situ atomic force microscopy (AFM) was used to investigate surface evolution during the growth of single crystals of turnip yellow mosaic virus (TYMV), cucumber mosaic virus (CMV) and glucose isomerase. Growth of these crystals proceeded by two-dimensional (2D) nucleation. For glucose isomerase, from supersaturation dependencies of tangential step rates and critical step length, the kinetic coefficients of the steps and the surface free energy of the step edge were calculated for different crystallographic directions. The molecular structure of the step edges, the adsorption of individual virus particles and their aggregates, and the initial stages of formation of 2D nuclei on the surfaces of TYMV and CMV crystals were recorded. The surfaces of individual TYMV virions within crystals were visualized, and hexameric and pentameric capsomers of the T = 3 capsids were clearly resolved. This, so far as we are aware, is the first direct visualization of the capsomere structure of a virus by AFM. In the cour se of recording the in situ development of the TYMV crystals, a profound restructuring of the surface arrangement was observed. This transformation was highly cooperative in nature, but the transitions were unambiguous and readily explicable in terms of an organized loss of classes of virus particles from specific lattice positions. © 2001 Elsevier Science B.V. All rights reserved.

Atomic force microscopy (AFM) can be applied both in situ and ex situ to study the growth of crystals from solution. The method is particularly useful for investigating the crystallization of proteins, nucleic acids and viruses because it can be carried out in the mother liquor and in a non-perturbing fashion. Interactions and transformations between various growth mechanisms can be directly visualized as a function of supersaturation, as can the incorporation of diverse impurities and the formation and propagation of defects. Because the crystals can be observed over long periods, it is also possible to obtain precise quantitative measures of the kinetic parameters for nucleation and growth. Finally, AFM has allowed us to identify a number of previously unsuspected phenomena that influence nucleation, rate of growth and the ultimate perfection of macromolecular crystals. These are all features which are important in determining the ultimate resolution and quality of a crystal's diffraction pattern.

There is a renewed interest in using Alfven waves (AW) in tokamak plasmas. Previously, AW were actively explored mostly for current drive and plasma heating in tokamaks. Presently, the possibility of the anomalous and neoclassical transport suppression by AW in tokamak plasmas is being vividly discussed. AW can also induce poloidal and toroidal plasma rotation. Toroidal plasma rotation can reach the subsonic level. These flows can substantially affect neoclassical transport both in collisional and weakly collisional plasmas. In this paper, the effect of plasma subsonic toroidal flows induced by Alfven waves on transport processes in the edge of elongated tokamak is investigated. The dependence of poloidal plasma rotation and ion heat conductivity on the elongation parameter and the ratio of induced toroidal velocity to the sonic speed are analytically obtained.

We study conformations assumed by single diblock star copolymers in a poor solvent by means of the Gaussian variational theory and Monte Carlo simulation in continuous space. Cases of stars with internal and external hydrophobic blocks are analysed. While in the former case the collapsed state has an obvious micellar shape, the latter case exhibits two nontrivial conformational structures. Apart from the equilibrium state of a globular hydrophobic core with hydrophilic daisy loops, one also finds here a metastable state of outstretched hydrophilic blocks with hydrophobic subglobules at their ends. Such a state appears to be rather long-lived during the kinetics of collapse of a swollen star. The plots of monomer densities and other observables computed by both techniques are found to be in good agreement with each other., RevTeX, 13 pages, 20 PS figures. Accepted for publication in Macromol. Theory Simul

We investigate the aggregation number and size distributions for inter-molecular clusters of amphiphilic diblock and triblock copolymers in poor solvent at very low concentrations. Diblocks and triblocks with hydrophilic ends are shown to possess narrow distributions corresponding to formation of monodispersed mesoglobules. Diblocks with hydrophobic ends are found to produce inter-cluster multimers due to bridging by the hydrophilic middle blocks, resulting in polydisperse distributions. Implications of these observations for preparation of monodispersed nanoparticles and, potentially, understanding of the quaternary structure of proteins are discussed., 4 pages, 4 PS figures. Accepted for publication in EPL

We study the formation of clusters consisting of several chains in dilute solutions of amphiphilic heteropolymers. By means of the Gaussian variational theory we show that in a region of the phase diagram within the conventional two-phase coexistence region mesoglobules of equal size possess the lowest free energy. Monte Carlo simulation confirms that the mesoglobules are stabilised due to micro-phase separation, which introduces a preferred length scale. The very existence of such mesoscopic structures is related to a delicate balance of the energetic and entropic terms under the connectivity constraints. The issue of size monodispersity and fluctuations for mesoglobules is investigated., 30 pages, RevTeX, 14 ps figures. Accepted for publication in J. Chem. Phys

The evolution of surface morphology and step dynamics during growth of single crystals of the protein Canavalin and of the cubic satellite tobacco mosaic virus crystals (STMV) have been investigated by in situ atomic force microscopy. These two crystals were observed to grow by very different mechanisms. Growth of Canavalin occurs on complex vicinal hillocks formed by multiple, independently acting screw dislocations. Small cluster were observed on the terraces. STMV on the other hand, was observed to grow by 2D nucleation of islands. No dislocations were found on the crystal. The results are used to determine the growth mechanisms and estimate fundamental materials parameters. The images also illustrate the important mechanism of defect incorporation and provide insight to the processes that limit the growth rate and uniformity of these crystals.