A technique for the local doping and correction of the conductivity of PbSnTe epitaxial layers via indium diffusion from superficial nanometer-thick films

A technique is described for the local indium doping of epitaxial films of a p-type PbSnTe solid solution to obtain a metal-insulator transition at liquid-helium temperatures. The indium was diffused from the surface of the film, from an In layer several nanometers thick, whereas the shape and size of the doped layer were set by a mask. It is emphasized that the oxide layer should be removed before indium deposition, and that the thickness of the deposited indium layer should be precisely chosen based on the thickness of the PbSnTe film. The results of using this technique for films having different compositions and the results of measurements performed on a planar p-i-p structure are considered.     

Conformational analysis and hemolytic activity of immunoglobulin G fragment 285-292 and its analogs

Theoretical conformational analysis was carried out for the 285-292 fragment of human immunoglobulin G (His-Asn-Ala-Lys-Thr-Lys-Pro-Arg) and its analogues containing Arg, Glu, Gly, Lys, or Trp residue instead of the His residue in position 1. Spectropolarimetic investigation of these peptides showed the analogues to have different activities in the C1q-mediated erythrocytes hemolysis assay. Comparison of the low-energy structures sets of the compounds tested allowed to suggest a model of the "biological active" conformation for the peptide molecule in the course of the C1q complement component binding.     

Features of the Current Flow in Injection Structures Based on PbSnTe:In Films

This paper reports a study of the current–voltage (I–V) features of the p-i-p structures based on Pb_1–xSn_xTe:In films with the tin content х ≈ 0.31 in which the metal–insulator transition occurs. It is shown that the photocurrent is the hole current under light interband excitation, and electron trapping is dominant. The experimental and theoretical data are compared.     

PbSnTe:In compound: Electron capture levels,galvanomagnetic properties,and THz sensitivity

A model of the Pb_1–x Sn _x Te:In compound, based on concepts of the theory of disordered systems is considered. The temperature dependences of the Fermi-level position and carrier concentration are calculated depending on the indium doping level and are compared with experimental data. The transient current–voltage characteristics are calculated in the mode of injection from the contact and current limitation by space charge at various voltage-variation rates. The data obtained are compared with the experiments. It is demonstrated that the shape of the characteristics is controlled by the parameters of electron capture at localized states. Photocurrent relaxation in a magnetic field is studied, and the mechanism of such relaxation is discussed under the assumption of the magnetic freezing of carriers.     

Interaction of Supercavitating Strikers with Underwater Obstacles

Journal of Engineering Physics and Thermophysics - The interaction of supercavitating strikers with obstacles placed in water was investigated in a wide range of intersection angles. Several...     

The morphology evolution of polyethylene produced in the presence of a Ziegler-type catalyst anchored on the surface of multi-walled carbon nanotubes

Data are presented on the evolution of the morphology of polyethylene (PE) formed via in situ polymerization with different polymer yield over a Ziegler-type titanium-magnesium catalyst anchored on the CNT surface. Individual polymer microparticles are formed on the CNT surface at the initial polymerization stage (the yield of 2.5–10 g PE/g CNT) with the formation of PE/CNT composites having a shish-kebab structure. As the polymer yield increases above 10 g PE per g CNT, the size of microparticles increases and the CNT surface gets totally covered with the polymer. We have found also a great effect produced by the morphology of initial CNT particle aggregates of individual nanotubes on the morphology of macroparticles in PE/CNT composites and the uniformity of CNTs distribution in PE/CNT composites. In the case of CNT samples with a loose structure of macroparticles (aggregates of entangled nanotubes), it is possible to obtain a homogeneous distribution of nanotubes in the polymer matrix of composites and increase the electrical conductivity of composites by 1–8 orders of magnitude by varying the CNT content in the composites from 0.9 to 2.8 wt%.     

Development of porous composite self-propagating high-temperature ceramics of the Ti-B-C system

The results of investigations into the porous composite ceramics produced from the Ti-B-C system by self-propagating high-temperature (SHS) synthesis are represented. The effect of the titanium amount in the charge and the billet density on the structure formation and strength characteristics of synthesized porous materials is studied. The results of their investigations using a JSM-6390A scanning electron microscope, an ARL X’TRA diffractometer, and an INSTRON 5988 universal testing machine are given.     

Photoconductivity of polymer compositions with a high content of organic dyes

Semiconductors - The photoconductivity of films of an amorphous molecular semiconductor based on poly-N-epoxypropylcarbazole with high contents of organic dye molecules and films of a polymer...