Tuning the electrically evaluated electron Lande g factor in GaAs quantum dots and quantum wells of different well widths

We evaluate the Lande g factor of electrons in quantum dots (QDs) fabricated from GaAs quantum well (QW) structures of different well width. We first determine the Lande electron g factor of the QWs through resistive detection of electron spin resonance and compare it to the enhanced electron g factor determined from analysis of the magneto-transport. Next, we form laterally defined quantum dots using these quantum wells and extract the electron g factor from analysis of the cotunneling and Kondo effect within the quantum dots. We conclude that the Lande electron g factor of the quantum dot is primarily governed by the electron g factor of the quantum well suggesting that well width is an ideal design parameter for g-factor engineering QDs

Scattering functions of knotted ring polymers

We discuss the scattering function of a Gaussian random polygon with N nodes under a given topological constraint through simulation. We obtain the Kratky plot of a Gaussian polygon of N=200 having a fixed knot for some different knots such as the trivial, trefoil and figure-eight knots. We find that some characteristic properties of the different Kratky plots are consistent with the distinct values of the mean square radius of gyration for Gaussian polygons with the different knots.Comment: 4pages, 3figures, 3table

Light scattering and phase behavior of Lysozyme-PEG mixtures

Measurements of liquid-liquid phase transition temperatures (cloud points) of mixtures of a protein (lysozyme) and a polymer, poly(ethylene glycol) (PEG) show that the addition of low molecular weight PEG stabilizes the mixture whereas high molecular weight PEG was destabilizing. We demonstrate that this behavior is inconsistent with an entropic depletion interaction between lysozyme and PEG and suggest that an energetic attraction between lysozyme and PEG is responsible. In order to independently characterize the lysozyme/PEG interactions, light scattering experiments on the same mixtures were performed to measure second and third virial coefficients. These measurements indicate that PEG induces repulsion between lysozyme molecules, contrary to the depletion prediction. Furthermore, it is shown that third virial terms must be included in the mixture's free energy in order to qualitatively capture our cloud point and light scattering data. The light scattering results were consistent with the cloud point measurements and indicate that attractions do exist between lysozyme and PEG.Comment: 5 pages, 2 figures, 1 tabl

Rashba spin-orbit interaction in a Mg_xZn_(1−x)O/ZnO two-dimensional electron gas studied by electrically detected electron spin resonance

We report the experimental determination of Rashba spin-orbit interaction (SOI) strength in two-dimensional electrons in a MgZnO/ZnO heterostructure using electrically detected electron spin resonance. The Rashba parameter is determined to be 7.0 × 10⁻¹⁴ eV m, which is the second smallest value among prevalent semiconductor heterostructures, following Si/SiGe. A long transverse spin relaxation time was derived to show a maximum value of 27 ns, owing to weak SOI. Our study demonstrates that the ZnO heterostructure is a promising candidate for spintronic devices utilizing long spin coherence

Overview of the current CRWMS repository design

This paper summarizes the current design for a potential geologic repository for spent fuels and high-level wastes at Yucca Mountain, Nevada. The objective of the paper is to present the key design features of the Mined Geologic Disposal System (MGDS) surface facilities and MGDS subsurface facilities. The paper describes the following: surface layout; waste handling operations design; subsurface design; and the underground transport and emplacement design. A more detailed presentation of key features is provided in the ``Reference design description for a geologic repository`` which is located on the YMP Homepage at www.ymp.gov

Heavy metal contamination of soil and sediment in Zambia

Heavy metal pollution is one of the most important problems in Zambia and causes serious effects to humans and animals. The aim of the present study was to evaluate the spatial distribution of heavy metals in main areas of Zambia and understand the characteristics of the pollution in each area. River and lake sediments and soil samples were collected from a large area of Zambia and analyzed for ten heavy metals (Cr, Co, Ni, Cu, Zn, As, Cd, Pb, Sr and Hg). The results indicate that heavy metal pollution in Zambia has strong regional differences. Using cluster analysis, the patterns of heavy metal pollution were divided into three major clusters: (1) Kabwe, (2) Copperbelt and (3) Lusaka and other areas. Heavy metals in the Copperbelt area are transported to downstream areas by the Kafue River. Pollution was also detected in national parks, and Lake Itezhi-tezhi has been polluted with high concentrations of Cu, possibly from mining activities in the upper reaches of the river. However, areas geographically distant from mining beds had only moderate or low heavy metal concentrations, although the concentrations of Pb and Zn were highly correlated with the populations of each town. Our findings indicate that heavy metal pollution in Zambia is still increasing, due to human activities, especially mining.Key words: Heavy metal, contamination, mining, soil, sediment

Current Mined Geologic Disposal System concept of operations

The concept of operations for the Mined Geologic Disposal System (MGDS) provides an integrated, conceptual description of the physical architecture and operating concept of the potential repository. The document facilitates a common understanding of the operations among system planners, developers and implementors by summarizing design solutions and operating concepts. During this past year, the MGDS Concept of Operations document was updated to reflect the Viability Assessment (VA) design and operating concept. Previously, this document reflected the Advanced Conceptual Design (ACD). This paper presents a description of the significant operational changes from ACD to VA design that are now captured in the concept of operations document

Tests of mode coupling theory in a simple model for two-component miscible polymer blends

We present molecular dynamics simulations on the structural relaxation of a simple bead-spring model for polymer blends. The introduction of a different monomer size induces a large time scale separation for the dynamics of the two components. Simulation results for a large set of observables probing density correlations, Rouse modes, and orientations of bond and chain end-to-end vectors, are analyzed within the framework of the Mode Coupling Theory (MCT). An unusually large value of the exponent parameter is obtained. This feature suggests the possibility of an underlying higher-order MCT scenario for dynamic arrest.Comment: Revised version. Additional figures and citation