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Notes: We have used the technique of molecular beam epitaxy to grow InAs on GaSb, GaSb on InAs, and InAs/InxGa1−xSb (0≤x≤0.4) multilayered structures and have performed a detailed investigation of the layers and resultant interfaces. The structures were grown on (100) oriented GaSb or GaAs substrates. Combined reflection high energy electron diffraction, x-ray photoelectron spectroscopy (XPS), and Auger electron spectroscopy (AES) studies indicate that Sb is persistently present on the InAs growth surface. XPS and AES analysis of InAs/GaSb heterojunctions indicates no compound formation at either the InAs/GaSb or GaSb/InAs interface. Secondary ion mass spectroscopy (SIMS) and XPS extinction profiles reveal the presence of approximately 5–10% As in the nominally pure GaSb layers. Analysis of InAs/GaSb/GaSb (100) structures by SIMS indicates that the As is incorporated during growth. The multilayer structures have been characterized by double crystal x-ray diffraction and the data has been modeled using kinematic formulations. We find that the experimental data is fitted by assuming atomically abrupt composition changes across the interfaces.

Notes: Multilayered films with an average concentration of Cu-16 at. % Au and a layering periodicity of 3.31 nm were produced by vapor deposition on sodium chloride substrates. Diffraction studies were carried out at Stanford Synchrotron Radiation Laboratory, thus allowing the observation of up to three orders of satellites, the evolutions of which were measured as a function of annealing time at 515 K. It was found that the first-order satellite intensity decayed nearly exponentially with time, whereas intensities of both second- and third-order satellites decreased very rapidly at first, then increased before decaying exponentially. These results could be explained by following the evolution of satellites during annealing of a one-dimensional modulated system governed by a nonlinear diffusion equation. The diffusivity in this system was assumed to be of the form D0+D1u+D2u2, with u=c−c0, where Di's are the coefficients, c is the concentration, and c0 represents the average composition of the alloy. The nonlinear diffusion equation was solved numerically to obtain one-dimensional concentration profiles at successive annealing times. Satellite amplitudes, obtained by Fourier transforming the concentration profiles, were found to exhibit a remarkable phenomenon: The mth-order satellite amplitude changes its sign (m−1) times before decaying asymptotically to zero. By comparing the evolution of the square of the amplitude with that of the satellite intensities, a set of Di's was determined that produced realistic concentration profiles and reproduced the experimentally evaluated satellite intensities reasonably well.

Notes: We present direct evidence for the dependence of critical thickness on growth temperature in a lattice-mismatched epitaxial system. Ge0.5Si0.5/Si strained-layer superlattices have been grown by molecular beam epitaxy on (100) Si substrates at temperatures between 330 and 530 °C. The extent to which lattice mismatch is accommodated by elastic strain has been determined through x-ray diffraction, channeled Rutherford backscattering spectroscopy, and transmission electron microscopy. Lattice mismatch is found to be accommodated purely elastically in a structure grown at 365 °C. Samples grown at higher temperatures are seen to display increasingly high densities of misfit-accommodating dislocations. This growth-temperature dependence may account for apparent inconsistencies in critical thickness data reported in the literature. Our results clearly demonstrate the need to account adequately for the kinetics of defect formation in the prediction of critical thicknesses.

Notes: Single crystal thin films of (111) oriented C60 are grown on epitaxial layers of single crystal antimony. The C60/Sb epitaxy is confirmed by low-energy electron diffraction which indicates that the [11¯0] in-plane directions are parallel in the two layers. X-ray diffraction shows that the C60 film is entirely (111) oriented and of high quality with sharp Bragg peaks and narrow mosaic spread. In this study the Sb films were grown on GaSb, to which they are lattice matched; however, since Sb can be epitaxially grown on surfaces with a large lattice mismatch this technique may be applied to integrate C60 single crystals onto many substrates or devices with a surface having sixfold symmetry.

Notes: Millimeter-sized single crystals of C60 were grown by sublimation of C60 powder in a vacuum for 6–24 h. The crystals had excellent facets, were free of C70 or solvent, and showed face-centered cubic symmetry with a very small mosaic spread down to 0.01°.

Notes: GaN p–i–n photovoltaic diode arrays were fabricated from epitaxial films deposited on sapphire by molecular beam epitaxy. Peak UV responsivity was 0.11 A/W at 360 nm, corresponding to 48% internal quantum efficiency. Visible rejection over 400–800 nm was 3–4 orders of magnitude. Typical pulsed time response was measured at 8.2 μs. Spectral response modeling was performed to analyze the photocurrent contributions from photogenerated carrier drift in the depletion region and from minority carrier diffusion in the p and n layers. With the model, a maximum internal quantum efficiency of 55% at 360 nm was calculated for the photovoltaic diode structure. © 1997 American Institute of Physics.

Notes: No association between HLA DP1 and the development of multiple basal cell carcinomas (BCC) was found among patients who had lived at least two-thirds of their lives in the tropics. The percentage of patients with multiple BCCS increased with age; this was different from what has been found in people living in the temperate zone of Australia.

Notes: In field experiments with spring wheat (Triticum aestivum L., cv. Neepawa), the low rate (0·02 kg ha-1) of chlorsulfuron significantly reduced wild oat control from individual applications of only barban and diclofop-methyl. The high rate (008 kg ha-1) affected wild oat control by all four graminicides, including difenzoquat and flam-prop-methyl. In most cases, the graminicides did not affect the broad-leaved weed control of chlorsulfuran. Overall, a low rate of chlorsulfuron in mixture with graminicides did not reduce wheat yield, whereas a high rate of chlorsulfuron in the mixtures gave a significant yield reduction compared with individual graminicides applied alone. All herbicide treatments increased wheat yield over the control. In the glasshouse, reduction in wild oat control by diclofop-methyl was directly related to the rate of chlorsulfuron added to diclofop-methyl. The effect of 0·02 kg ha-1 chlorsulfuron on control of wild oat was decreased when the rate of diclofop-methyl increased from 0·5 to 0·9 kg ha-1 and was completely eliminated when diclofop-methyl reached 1·1 kg ha-1. Conversely, diclofop-methyl (0·7 and 1·1 kg ha-1) gave some reduction of wild mustard (Sinapis arvensis L.) and redroot pigweed (Amaranthus retrofiexus L.) control by chlorsulfuron (0·01 and 0·02 kg ha-1), even though in some cases diclofop-methyl/chlorsul-furon gave better control of these broad-leaved weeds. In the laboratory, the absorption and translocation of [14C]-diclofop-nieihyl in wild oat seedlings were significantly reduced when chlorsulfuron was added, compared with [14C]-diclo-fop-methyl applied alone.Effet du chlorsulfuron sur l'efficacité et l'effet sur le rendement de quatre graminicidesDans des essais de plein champ sur blé de printemps (Triticuni aestivum L., cv. Neepawa), la faible dose (0, 02 kg ha-1) de chlorsulfuron a réduit significativement l'efficacité d'une application séparée de barbane et de diclofop-methyl. La forte dose (0, 08 kg ha-1) a contrarié la destruction de la folle avoine pour les quatre graminicides dont le difenzoquat et le flamprop-methyl. Dans la plupart des cas, les graminicides n'ont pas eu d'incidence sur la destruction des dicotylédones par le chlorsulfuron. Par ailleurs. une faible dose de chlorsulfuron en mélange avec les graminicides n'a pas réduit le rendement en blé, en revanche, une forte dose de chlorsulfuron en mélange a entrainé une baisse significative de rendement en comparaison des graminicides appliqués seuls. Tous les traitements herbicides ont entrainé un gain de rendement par rapport au témoin non traité. En serre, la réduction d'efficacité sur folle avoine du diclofop-methyl était directement correlée à la dose de chlorsulfuron ajouté. Les effets de 0, 02 kg ha-1 sur la destruction de la folle avoine baissaient quand le niveau de diclofop-methyl augmentait de 0,5 à 0,9 kg ha-1 et étaient complètement éliminés quand la dose de diclofop-methyl atteignait 1, 1 kg ha-1. Par ailleurs, le diclofop-méthyl (0,7 et 1,1 kg ha-1) a réduit l'efficacité du chlorsulfuron (0,01 et 0,02 kg ha-1) sur la sanve (Sinapis arvensis L.) et l'amaranthe réflechie (Amaranthus retroflexus L.) même si dans certains cas l'association diclofop-mélhyl-chtorsulfuron a eu une meilleure efficacité sur ces mauvaises herbes. Au laboratoire, l'ab sorption et la translocation du diclofop-methyl C14 dans les plantules de folle avoine ont été réduites significativement par l'addition de chlor-sulfuron en comparaison du diciofop-méthyl C14 appliqué seul.Wirkung von Chlorsulfuron zusammen mil Vier Graminiziden auf die Unkrautbekämpfung und den Ertrag von WeizenIn Freilandversuehen mit Sommerweizen (Triticum aesttotm L. ‘Neepawa’) verminderie Chlorsulfuron in niedriger Aufwandmenge (0,02 kg ha-1) den Bekämpfungserfolg gegen Flug-Hafer nur bei Barban und Diclofop-menthyl. Die hohe Aufwandmenge (0,08 kg ha-1)beeinträchtigte die Wirkung aller 4 Graminizide, einschliesslich Difenzoquat und Flamprop-methyl. Die Graminizide beeinfiussten die Wirkung von Chlorsulfuron gegen zweikeimblättrige Arten meistens nicht, Der Weizenertrag blieb bei der Mischung der niedrigen Aufwandmenge von Chlorsulfuron mit den Graminiziden unverändert, die hohe Aufwandmenge führte aber in den Mischungen zu einem signifikaten Abfall des Ertrags, vergli-chen mit dem bei Anwendung der Graminizide allein. Mit allen Herbizidbehandlungen wurden gegenüber Unbehandelt höhere Erträge erzielt. Im Gewächshaus war die Wirkung von Diclofopmethyl gegen Flug-Hafer direkt von der zugefügten Menge an Chlorsulfuron abhängig. Der Einfluss von 0,02 kg ha-1 Chlorsulfuron aif die Bekämpfung von Fiug-Hafer nahm ab. wenn die Aufwundmenge von Diclofop-methyl von 0,5 auf 0,9 kg ha-1 gesteigert wurde; bei 1, 1 kg ha-1 Diclofop-methyl war er aufgehoben. Andererseits trat bei 0,7 und 1,1 kg ha-1 Diclofop-methyl eine Minderung der Wirkung von Chlosulfuron (0,01 und 0,02 kg ha-1) gegen Acker-Senf (Sina-psis arvensis L.) und Zurückgekrümmten Fuchsschwanz (Amarenthus retroflexus L.) ein, wenn auch dise Mischung in einigen Fällen gegen dise Arten starker wirkte. Im Labor wurde einc signifikant geringere Absorption und Trans-lokation von 14C-Diclofop-methyl in Keimpflan-zen des Flug-Hafers beobachtet, wenn Chlorsulfuron zugefügt worden war.

Notes: Five field experiments were conducted from 1972 to 1975 to evaluate weed control in flax (Linum usitatissimum L.) using post-emergence treatments of asulam [methyl (4-aminobenzenesulphonyl) carbamatel alone and in combination with other herbicides. The 14C-asulam absorption by leaf segments and roots of glasshouse grown wild oats (Avena fatua L.) was also investigated. Asulam at 1.12 kg/ha gave good wild oat control and acceptable control of green foxtail (Setaria viridis (L.) Beauv.). However, wild oat control was poorer when asulam was combined with other herbicides: on a 3-year average, as compared with asulam alone at equal rates, the asulam+MCPA mixture resulted in a greater antagonism and a significant 6% reduction in flax seed yield, whereas the asulam+bromoxynil/MCPA mixture gave the least antagonistic effect, improved broadleaf weed control and increased yield by 13%. In mixtures, the potassium salt of MCPA was more compatible with asulam for weed control than the amine form. Both leaf segments and roots of wild oats absorbed and distributed less 14C-asulam from solutions containing MCPA than from those containing bromoxynil or bromoxynil/MCPA.