Short-range order and electronic properties of epitaxial graphene

One of the most rapidly developing areas of modern materials science is the study of graphene and materials on its basis. The experimental investigations have revealed different types of defects on the surface of graphene that form the ordered structures of atomic configurations. In the present work, the value of short-range order parameter for different configurations of foreign atoms in a graphene layer was calculated. The effect of various factors on the density of electronic states and electrical resistance in graphene was also investigated. The type of the ordering of foreign atoms in graphene rather than the concentration of impurities, was shown to be responsible for the change in the conductivity of graphene

Short-range order and electronic properties of epitaxial graphene

One of the most rapidly developing areas of modern materials science is the study of graphene and materials on its basis. The experimental investigations have revealed different types of defects on the surface of graphene that form the ordered structures of atomic configurations. In the present work, the value of short-range order parameter for different configurations of foreign atoms in a graphene layer was calculated. The effect of various factors on the density of electronic states and electrical resistance in graphene was also investigated. The type of the ordering of foreign atoms in graphene rather than the concentration of impurities, was shown to be responsible for the change in the conductivity of graphene

Etude et realisation d'un epurateur a trichlorethylene adapte aux machines a degraisser les metaux

SIGLECNRS-CDST / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

Changes in the Quantum of Russian Fertility During the 1980s and Early 1990s

To investigate whether Russia's dramatic fertility changes pre- and post-Soviet times were due primarily to tempo effects, as has been argued recently, or to quantum effects, this study standardizes for factors that distort conventional fertility indexes. A time series spanning 1978-93 of period parity-progression ratios for the Russian Federation is constructed applying the PADTFR technique, which takes into account age, parity, and time elapsed since the birth of the previous child, to data from the Russian micro census of February 1994 (2.8 million maternity histories). Both the fertility rise of the 1980s and the fertility fall of the early 1990s are found to be primarily due to changes in the probability of a second birth. The impact of tempo on the conventional TFR is significant, but of relatively minor magnitude in comparison to changes in the quantum of fertility. The social and economic context in which the fertility change took place is described. Copyright 2005 The Population Council, Inc..