The starting stress for dislocations in a superlattice

The forces on superdislocations due to the state of the antiphase boundaries (APB) are examined as functions of temperature and concentration on the basis of a previously expounded theory of component concentrations and degree of order at APB in superlattices of CsCl type. Forces due to loss of position correlation in the glide plane are also examined. It is considered that the yield points of superlattices as functions of concentration may be explained by these mechanisms.     

Sintering in Cu-Al powders

Various methods of examination have been applied to Cu-Al alloys (10 at. % Al) during sintering over a wide temperature range. The density change is found to result from balance between shrinkage and volume growth.     

Calculation of the deceleration of a viscous supersonic gas flow in a channel

The deceleration of nonuniform viscous supersonic gas flows in planar and axisymmetric channels is investigated. A modification of Prandtl's formula for the turbulent viscosity is proposed in order to take into account the dependence of the mixing length on the value of the axial Mach number. The results of the calculations are compared with known experimental data on the deceleration of a supersonic flow in a subsonic pseudoshock.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 162–166, March–April, 1982.We thank A. N. Sekundov for discussing the work.     

Preparative synthesis of functionally substituted esters of dehydroabietic and 4,4′-biphenyldicarboxylic acids

A preparative synthesis of functionally substituted esters of dehydroabietic and 4,4-biphenylcarboxylic acids by the reaction of chlorides of these acids with alcohols in the presence of pyridine is developed. 4,4-Biphenyldicarbonyl dichloride reacts with hydroperoxides to form peroxy esters and with lithium alcoholates, which allows preparation of the corresponding ethers derived from secondary and tertiary alcohols.Translated from Zhurnal Obshchei Khimii, Vol. 74, No. 8, 2004, pp. 1360–1364.Original Russian Text Copyright © 2004 by Dikusar, Yuvchenko, Kozlov, Olkhovik, Potkin.This revised version was published online in April 2005 with a corrected cover date.     

Two-detector reactor neutrino oscillation experiment Kr2Det at Krasnoyarsk: Status report

We consider the status of the Kr2Det project aimed at sensitive searches for neutrino oscillations in the atmospheric neutrino mass parameter region around Δm² ～ 3×10^?3 eV² and at obtaining new information on the electron neutrino mass structure (U_e3).     

New data processing technique based on the optimal control theory

The problem of choosing the best set of parameters for a given mathematical model that adequately describes independent experimental data is formulated in terms of the optimal control theory. The sum of squares of discrepancies between experimental data and their analogues calculated within the framework of a given mathematical model of a process is minimized. A solution to the problem is found, and conditions for optimally choosing the parameters of the mathematical model are established. The search algorithm is generalized for the case where a penalty function is present, and an efficient way of including inequality constraints is suggested. The algorithm was tested by finding the thermal conductivity of single crystals (Ioffe-Ioffe classical experiment), thermal diffusivity of a thin plate, and parameters of gene expression during the fruit fly (Drosophila melanogaster) embryo evolution.     

Sterical Hindrances as a Driving Force of Skeleton Rearrangements of Fenchone and Its Oxime in Ritter Reaction

Fenchone (1,3,3-trimethylbicyclo[2.2.1]heptan-2-one) in reaction with acetonitrile in the presence of sulfuric acid (Ritter reaction) due to steric hindrances preventing geminal addition of two nucleophile molecules gives rise to a mixture of 1,2-exo-diacetamido-6-endo,7,7-trimethylbicyclo[2.2.1]heptane, 2-endo6-exo-diacetamido-3,3,6-trimethylbicyclo[2.2.1]heptane, and 2-exo,6-exo-diacetamido-1,3,3-tri- methylbicyclo[2.2.1]heptane in the ratio of 6:4:1. Fenchone oxime under condition of this reaction affords a mixture of stereoisomeric cis- and trans-acetamido-1-methyl-3-(-cyanoisopropyl)cyclopentanes in 2:3 ratio.