<Superscript>137</Superscript>Cs content and vertical migration in littoral soil of two lakes in Bryansk Oblast

The dynamics and present state of the radioactive contamination with ¹³⁷Cs of littoral soil of Lake Kozhanovskoe and Lake Svyatoe on the Besed’ River are presented. The parameters of the vertical migration of ¹³⁷Cs in soil-the rate of directional transfer with soil moisture, the diffusion coefficient, and the average velocity of vertical migration-are estimated by comparing the experimental and model distributions of ¹³⁷Cs content over soil depth. It is shown that at the present time the two 5-cm layer of soil can contain 20–90% ¹³⁷Cs depending on the type of soil and landscape. The average values of the diffusion coefficient, the rate of directional transfer, and the vertical migration velocity for 12-, 13-, and 20-year periods after the Chernobyl accident are 0.1–2.8 cm²/yr, 0.1–0.3 cm/yr, and 0.1–0.8 cm/yr, respectively. __________ Translated from Atomnaya énergiya, Vol. 102, No. 5, pp. 306–311, May, 2007.     

Morphogenesis of the vena cava inferior roots in human embryogenesis

The roots of the vena cava inferior are formed during the 2nd month of human embryogenesis in the course of transformation of posterior caudal veins and their tributaries, including anastomoses with umbilical veins, which is associated with the growth of pelvic kidney and lower extremities. The roots and initial part of vena cava inferior originate from secondary cardinal veins, primarily from sacrocardinal anastomosis and sacrocardinal veins proximal regions.     

A new recombination center in heavily doped GaAs: Zn grown by liquid-phase epitaxy

The photoluminescence properties of p-GaAs: Zn (100) layers grown by liquid-phase epitaxy from gallium and bismuth melts at various temperatures have been studied. It is shown that a novel radiative recombination center is formed in these layers. The concentration of the centers increases with the doping level in proportion to the concentration of free holes raised to the power 5.35±0.1. The exponent is independent of the growth melt (gallium or bismuth) and the growth temperature. It is found that the center is a neutral complex consisting of an antisite defect of gallium at an arsenic site and two arsenic vacancies. Fiz. Tekh. Poluprovodn. 32, 1184–1189 (October 1998)