Structural Characterization of Doped GaSb Single Crystals by X-ray Topography

We characterized GaSb single crystals containing different dopants (Al, Cd and Te), grown by the Czochralski method, by x-ray topography and high angular resolution x-ray diffraction. Lang topography revealed dislocations parallel and perpendicular to the crystal's surface. Double-crystal GaSb 333 x-ray topography shows dislocations and vertical stripes than can be associated with circular growth bands. We compared our high-angular resolution x-ray diffraction measurements (rocking curves) with the findings predicted by the dynamical theory of x-ray diffraction. These measurements show that our GaSb single crystals have a relative variation in the lattice parameter ({Delta}d/d) on the order of 10{sup -5}. This means that they can be used as electronic devices (detectors, for example) and as x-ray monochromators

Drug transporters: recent advances concerning BCRP and tyrosine kinase inhibitors

Multidrug resistance is often associated with the (over)expression of drug efflux transporters of the ATP-binding cassette (ABC) protein family. This minireview discusses the role of one selected ABC-transporter family member, the breast cancer resistance protein (BCRP/ABCG2), in the (pre)clinical efficacy of novel experimental anticancer drugs, in particular tyrosine kinase inhibitors

Divide and Privatize: Firms Break-Up and Performance

We analyze the long-term effects of divesture and ownership change on corporate performance. We employ a unique data set for a large number of Czech firms spanning the period 1996-2005. We employ a propensity score matching procedure to deal with endogeneity problems. Our results, which are generally in line with the positive effects of divestiture found in the developed-market literature, show that the initial effects of divestiture are positive but after a certain point they quickly diminish over time

Size Effect on Shear Strength of Reinforced Concrete: Is CSCT or MCFT a Viable Alternative to Energy-Based Design Code?

After sketching the history of the size effect models for the shear strength of reinforced concrete (RC) in design codes, the energy-based size effect law (SEL), recently incorporated into the American Concrete Institute (ACI) design code articles for beam shear and slab punching, is briefly discussed. A general derivation of the SEL based only on the first principles involving energy conservation and dimensional analysis (or laws of similitude) is presented. Attention is then focused on recent articles that present a severe critique of the SEL and various arguments in support of the Muttoni et al.'s critical shear crack theory (CSCT)-an update of the Collins et al.'s modified compression field theory (MCFT)-that some researchers propose to be introduced into the fib Model Code and the Eurocode as an alternative to the SEL. In a point-by-point analysis, it is shown that this critique and these arguments are incorrect and baseless. It is hoped that the present clarification would lead to progress in design codes, enhancing the safety and efficiency of RC structures. (c) 2020 American Society of Civil Engineers

Microsoft Word - Bazant-Framcos-Fracturing_headers+footers_.doc

ABSTRACT: The paper summarizes three recent advances in the modeling of inelastic behavior and fracturing of concrete, achieved at Northwestern University and Politecnico di Milano. First, improvements of microplane model M4 which allow a more realistic simulation of frictional shear and of lateral strains in tensile fracturing are presented. Second, development of microplane model M5 which can capture the transition from distributed cracking damage to complete cohesive fracture is described and its novel concept-a combination of kinematic and static constraints-is discussed. Third, a new lattice type model for concrete, which can simulate (with the same material parameters) tensile fracturing, complete cohesive fracture, compression-shear behavior with softening at zero or mild confinement, and response at confined compression at which there is only hardening (i.e., no peal and no postpeak softening), is outlined

A versatile X-ray topographic camera with elastic translation

A versatile X-ray topographic Lang camera was developed and tested. A simple and easy-to-build elastic system driven by a stepping motor is used to avoid expensive and sophisticated bearings normally required for highly precise translation. After initial and permanent corrections for repetitive angular deviation (yaw), the angular stability was 10 µrad for a 30 mm translation during a 16 h run. Topographical images taken with this camera show that it is a reliable and thermomechanically stable apparatu