Regions of the genome that affect agronomic performance in two-row barley

Quantitative trait locus (QTL) main effects and QTL by environment (QTL × E) interactions for seven agronomic traits (grain yield, days to heading, days to maturity, plant height, lodging severity, kernel weight, and test weight) were investigated in a two-row barley (Hordeum vulgare L.) cross, Harrington/TR306. A 127-point base map was constructed from markers (mostly RFLP) scored in 146 random double-haploid (DH) lines from the Harrington/TR306 cross. Field experiments involving the two parents and 145 random DH lines were grown in 1992 and/or 1993 at 17 locations in North America. Analysis of QTL was based on simple and composite interval mapping. Primary QTL were declared at positions where both methods gave evidence for QTL. The number of primary QTL ranged from three to six per trait, collectively explaining 34 to 52% of the genetic variance. None of these primary QTL showed major effects, but many showed effects that were consistent across environments. The addition of secondary QTL gave models that explained 39 to 80% of the genetic variance. The QTL were dispersed throughout the barley genome and some were detected in regions where QTL have been found in previous studies. Eight chromosome regions contained pleiotropic loci and/or linked clusters of loci that affected multiple traits. One region on chromosome 7 affected all traits except days to heading. This study was an intensive effort to evaluate QTL in a narrow-base population grown in a large set of environments. The results reveal the types and distributions of QTL effects manipulated by plant breeders and provide opportunities for future testing of marker-assisted selection

Metallization technology for tenth-micron range integrated circuits. CRADA final report for CRADA number ORNL92-0104

A critical step in the fabrication of integrated circuits is the deposition of metal layers which interconnect the various circuit elements that have been formed in earlier process steps. In particular, columns of metal 2-3 times higher than the characteristic dimension of the circuit are needed. At the time of initiation of this CRADA, the state-of-the-art was the production of 1-1.5 micron-high columns for 0.5 micron-wide features with an expected reduction in size by a factor of two or more within five to ten years. Present commercial technologies cannot deposit such features with the process temperature, aspect ratio (ratio of height to diameter), and/or materials capability needed for future devices. This CRADA had the objective of developing a commercial tool capable of depositing metal (either copper or aluminum) at temperatures below 300{degrees}C into features with sizes approaching 0.2 micron on 200-mm wafers. The capability of future modification for deposition of alloys of controllable composition was also an important characteristic. The key technical accomplishments of this CRADA include the development of a system capable of delivering highly ionized metal plasmas, refinement of spectroscopic techniques for in situ monitoring of the ion/neutral ratio, use of these plasmas for filling and lining submicron trenches used for integrated circuit fabrication, and generation of fundamental data on the angular dependent sputtering yield which will prove useful for modeling the time evolution of feature filling and lining

X-ray photoelectron spectroscopy (XPS) studies of oxygen and carbon bonding to tokamak walls

The binding energies of surface atoms of stainless steel samples exposed to hydrogen plasma discharges in PDX are measured using X-ray Photoelectron Spectroscopy. After glow discharge conditioning the O/sub 1s/ line is completely shifted to a higher binding energy which is an indication of the formation of hydroxides. The Fe/sub 2p/ lines show a partial reduction of iron. After high power discharges, the oxygen concentration increases and the binding energy of the deposited O atoms corresponds to a metallic oxide. The deposited limiter material Ti is also completely oxidized. For both kinds of discharges the binding energies of Cr/sub 2p/ and C/sub 1s/ remain essentially unmodified

In-situ impurity measurements in PDX Edge plasma

The surface analysis station of PDX combines several surface analysis techniques (AES, XPS, SIMS) for in-situ measurement of impurity fluxes in the edge-plasma. The major impurities deposited on a sample surface during nondiverted PDX discharges are oxygen, titanium (limiter material) and chlorine. The impurity fluxes measured at different radial positions decreased by a factor of ten from the plasma edge to the wall. The sample surface collecting the impurity ions is located behind a circular aperture. The observed broadening of the deposition profile of Ti relative to the aperture diameter enables an estimate to be made of the ratio of charge state/energy of Ti ions in the edge plasma. Time-resolved analyses of the deposited impurities are presented which indicate that the time behavior for various impurities may be quite different for different impurity species. This aspect is discussed in relation to probable impurity release mechanisms

Glow discharge conditioning of the PDX vacuum vessel

A glow discharge technique has been developed and applied to the conditioning of the large (38 m/sup 3/) Poloidal Divertor Experiment (PDX) vacuum vessel. The discharge parameters and working gas (H/sub 2/) were chosen to maximize C and O removal and minimize metal sputtering. The glow discharge was produced by biasing one or two internal anodes at 400 V to sustain a discharge current of 2 to 4 A per anode. Purified H/sub 2/ at a pressure of 3 x 10/sup -2/ torr was flowed through PDX at approx. 10 t-l/s. The effectiveness of the glow discharge conditioning was monitored by measuring impurity gas (CH/sub 4/, C/sub 2/H/sub 4/, and CO) exhaust rates by mass spectrometry and C and O surface removal rates by in-situ AES and XPS

Observations of changes in residual gas and surface composition with discharge cleaning in PLT

Hydrogen discharge cleaning of the PLT vacuum vessel has been studied by mass spectroscopy of desorbed gases and surface analysis of exposed samples. Several modes of vessel conditioning have been studied to date: (1) a high power discharge cleaning (PDC) mode, with a peak power density to the vessel wall P/sub s/ approximately 0.6 w/cm/sup 2/ and a peak electron temperature T/sub e/ approximately 100 ev; (2) low power (Taylor-type) discharge cleaning (TDC) with P/sub s/ approximately 0.05 w/cm/sup 2/ and T/sub e/ equal to or less than 5 eV. The predominant residual gases produced during PDC are CH/sub 4/ (1-5 x 10/sup -6/ torr) and CO (1-10 x 10/sup -7/ torr), whereas TDC produced primarily H/sub 2/O (1-2 x 10/sup -6/ torr) and CH/sub 4/ (1-10 x 10/sup -7/ torr). In situ surface analysis of hydrocarbon-covered stainless steel has shown significant decreases in carbon coverage occurring after 10/sup 3/-10/sup 4/ pulses of either cleaning mode. Observed changes in oxygen coverage are more difficult to interpret because of the presence of the nascent oxide layer on the stainless steel substrates

Long-term changes in the surface conditions of PLT

Long-term changes in the surface conditions of the PLT vacuum vessel wall have been monitoried by the periodic analysis of a variety of sample substrates (stainless steel, alumina, silicon), exposed to PLT discharges for periods of up to several months and subsequently removed for analysis by Auger electron spectroscopy (AES), photoelectron spectroscopy (ESCA), ion backscattering, nuclear reaction analysis, secondary ion mass spectrometry (SIMS), and scanning electron microscopy. Samples exposed for extended time periods (2 to 6 months) showed deposited films containing limiter (W) and liner constituent metals (Fe, Cr, and Ni) and C and O. The film thicknesses ranged between 100 to 200 A with 2 to 15 atomic percent W and 5 to 40 percent Fe as determined by sputter-AES and ion backscattering measurements. Increased deposition of metallic impurities (W, Fe) was noted following the first extensive application of low power discharge cleaning. We discuss possible mechanisms responsible for the deposition of metals onto the sample surfaces. Deuterium retention was observed in all the exposed samples with the deuterium depth profiles restricted primarily to the deposited films on the stainless steel substrates and extending deeper for Si. The deuterium retained in the exposed samples shows a saturation at (1 to 11) x 10/sup 15/D atoms/cm/sup 2/ for an estimated variation in the deuterium fluence of 10/sup 17/ to 10/sup 19/D atoms/cm/sup 2/

Hydrogen isotope trapping in materials exposed in PLT

Samples exposed at various minor radii in PLT to small numbers of high power discharges have been analyzed for the amount and depth distribution of implanted hydrogen isotopes and higher Z impurities. Comparisons of the measured H,D concentrations and depth profiles with laboratory implantations and calculated depth profiles give the energy and fluence of the hydrogen implanted in the PLT samples. For a Maxwellian distribution, characteristic temperatures of 500 to 600 eV due to plasma charge exchange, and 50 to 350 eV due to ions at the plasma edge are obtained. Also a 5 to 40 keV component is observed due to neutral beam injection