Current flow through metal shunts in ohmic contacts to n +-Si

It is experimentally found that an ohmic contact based on Au-Pt-Ti-Pd-n ⁺-Si metallization is formed due to nanoscale metal shunts containing Si, Au, and Pt in the region of the interface with n ⁺-Si, which appears during heat treatment at T = 450°C for 10 min in a vacuum chamber with a residual pressure of 10^?6 Torr. The high density of shunts adjoining dislocations and other imperfections is confirmed by the temperature dependence of the specific contact resistance ρ _c (T). The density of conductive dislocations, calculated from the temperature dependence of ρ _c is ～5 × 10⁹ cm^?2 which correlates with the density of structural defects, determined by the etch pits after removal of the metallization layers.     

A Beta Spectrometer Based on Silicon Detectors

The characteristics of a beta spectrometer that consists of a total-absorption Si(Li) detector and a drift Si detector are presented. Using this spectrometer, it is possible to efficiently separate β radiation of nuclei from concomitant X and γ rays. The method is based on coincidences between signals from the thick and thin detectors. The spectrometer can be used to precisely measure the shape of the β spectra of various radioactive nuclei, in particular, of the ¹⁴⁴Pr nucleus, which is the most promising antineutrino source for searching for neutrino oscillations into a sterile state.     

Deposition of Films Based on Americium Isotopes by Vapor-Phase Thermal Decomposition of β-Diketonates and Their Adducts with Neutral Ligands

Deposition of ²⁴³Am-based films by vapor-phase thermal decomposition of the americium hexafluoroacetylacetonate adduct Am(HFA)₃·2TBP was studied. Films containing from fractions of microgram to several tens of micrograms of ²⁴³Am are deposited on iron, stainless steel, aluminum, and copper supports in a forevacuum (10^{- 2} mm Hg) at 340-400°C. The highest yields of ²⁴³Am deposition (75-85%) were obtained on iron and steel supports. Americium is presumably deposited in the form of AmF₃.     

Holographic and speckle interferometry in examining the deformed state of gear teeth in bending

Strength of Materials -     

Initiation and propagation of nuclear burning wave in fast reactor

The regime of the nuclear burning wave (NBW) in a fast reactor (FR) is described using the non-stationary diffusion equation for neutron transport and equations of the fuel component burn-up and of nuclear kinetics for precursor nuclei of delayed neutrons. A critical two-zone fast reactor of cylindrical form with metal fuel of the U–Pu cycle is considered. The initiation of nuclear burning in an enriched ignition zone by means of an external neutron flux that is turned off at an early stage of FR operation has been simulated. The possibility of creating a self-organizing regime of a running NBW in the breeding zone along the reactor axis has been demonstrated. The neutron leakage in a transverse direction was taken into account using the concept of radial buckling. The calculation results of the space–time evolution of neutron flux in this system using the effective multi-group approximation are presented. The average fuel burn-up is about 50%. The velocity of NBW propagation strongly depends on the transverse size of FR. For example, in the reactor of 110 cm radius and 500 cm length the NBW velocity is about 22 cm/year.     

Heat transfer in a retarded fluidized bed

An oscillation model of a fluidized bed is used to examine the effect of the degree of retardation of the bed on external heat transfer.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 50, No. 3, pp. 445–451, March, 1986.     

Red Fluorescent Turn‐On Ligands for Imaging and Quantifying G Protein‐Coupled Receptors in Living Cells

Classical fluorescence‐based approaches to monitor ligand–protein interactions are generally hampered by the background signal of unbound ligand, which must be removed by tedious washing steps. To overcome this major limitation, we report here the first red fluorescent turn‐on probes for a G protein‐coupled receptor (oxytocin receptor) at the surface of living cells. The peptide ligand carbetocin was conjugated to one of the best solvatochromic (fluorogenic) dyes, Nile Red, which turns on emission when reaching the hydrophobic environment of the receptor. We showed that the incorporation of hydrophilic octa(ethylene glycol) linker between the pharmacophore and the dye minimized nonspecific interaction of the probe with serum proteins and lipid membranes, thus ensuring receptor‐specific turn‐on response. The new ligand was successfully applied for background‐free imaging and quantification of oxytocin receptors in living cells.     

A proximate method for determining the refractive indices of liquids

A simple method for measuring the refractive index of liquids that fill thin-wall cylindrical cells of any diameter is described. The method is based on the light-refraction phenomenon in cylindrical lenses and is implemented using a system of lines that are regularly positioned in a plane and are observed in monochromatic light through a liquid-filled cylinder. Images of lines are turned relative to the initial orientation, and the rotation angle is unambiguously related to the refractive index of the liquid.