The interaction of small metal particles with refractory oxide supports

Islands and continuous layers of Pd were grown in UHV on Mo and MoO subtrates. As-deposited Pd islands and layers exhibited bulk Pd adsorption properties for CO when the Pd had been deposited at RT and at thicknesses exceeding 3 ML. However, CO adsorption was drastically reduced upon annealing. This deactivation was interpreted in terms of substrate/support interaction involving the diffusion of substrate species toward the Pd surface, using AES, TPD, and work function measurement techniques. A study of the growth and annealing behavior of Pd on Mo(110) was made for thicknesses up to 12 monolayers and substrate temperatures up to 1300K, using AES, XPS, LEED, and work function measurements. At low tempertures Pd formed a monolayer without alloying. In thick layers (12 ML) annealed about 700 K, Mo diffusion into the Pd layer and alloying were noted. Such layers remained continuous up to 1100 K. Thinner Pd layers were less stable and started coalescing upon annealing to as little as 550 K. Significant changes in Pd Auger peak shape, as well as shifts of Pd core levels, were observed during layer growth and annealing

Size and shape dependence of CO adsorption sites on sapphire supported Fe microcrystals

The surface structure and stoichiometry of alumina substrates, as well as the size, growth characteristics, and shape of Fe deposits on sapphire substrates have been investigated by low energy electron diffraction (LEED), Auger electron spectroscopy, electron energy loss spectroscopy, and X-ray photoemission spectroscopy (XPS), as well as work function measurements, in conjunction with transition electron microscopy observations. The substrates used in this work were the following: (1) new, clean Al2O3; (2) same surface amorphized by Ar ion bombardment; (3) same surface regenerated by 650 C annealing; (4) amorphous alumina films on Ta slab; and (5) polycrystal alumina films, obtained by heating amorphous films to 600 C. Substrate cleaning was found to be most effective in producing a reproducible surface upon oxygen RF plasma treatment. The Fe nucleation and growth process was found to depend strongly on the type of substrate surface and deposition conditions. Ar ion bombardment under beam flooding, and subsequent annealing at 650 C was found an effective means to restore the original Al2O3 (1102) surface for renewed Fe deposition

A temperature-dependent phase-field model for phase separation and damage

In this paper we study a model for phase separation and damage in thermoviscoelastic materials. The main novelty of the paper consists in the fact that, in contrast with previous works in the literature (cf., e.g., [C. Heinemann, C. Kraus: Existence results of weak solutions for Cahn-Hilliard systems coupled with elasticity and damage. Adv. Math. Sci. Appl. 21 (2011), 321--359] and [C. Heinemann, C. Kraus: Existence results for diffuse interface models describing phase separation and damage. European J. Appl. Math. 24 (2013), 179--211]), we encompass in the model thermal processes, nonlinearly coupled with the damage, concentration and displacement evolutions. More in particular, we prove the existence of "entropic weak solutions", resorting to a solvability concept first introduced in [E. Feireisl: Mathematical theory of compressible, viscous, and heat conducting fluids. Comput. Math. Appl. 53 (2007), 461--490] in the framework of Fourier-Navier-Stokes systems and then recently employed in [E. Feireisl, H. Petzeltov\'a, E. Rocca: Existence of solutions to a phase transition model with microscopic movements. Math. Methods Appl. Sci. 32 (2009), 1345--1369], [E. Rocca, R. Rossi: "Entropic" solutions to a thermodynamically consistent PDE system for phase transitions and damage. SIAM J. Math. Anal., 47 (2015), 2519--2586] for the study of PDE systems for phase transition and damage. Our global-in-time existence result is obtained by passing to the limit in a carefully devised time-discretization scheme

A Weakly nonlinear theory for spiral density waves excited by accretion disc turbulence

We develop an analytic theory to describe spiral density waves propagating in a shearing disc in the weakly nonlinear regime. Such waves are generically found to be excited in simulations of turbulent accretion disks, in particular if said turbulence arises from the magneto-rotational instability (MRI). We derive a modified Burgers equation governing their dynamics, which includes the effects of nonlinear steepening, dispersion, and a bulk viscosity to support shocks. We solve this equation approximately to obtain nonlinear sawtooth solutions that are asymptotically valid at late times. In this limit, the presence of shocks is found to cause the wave amplitude to decrease with time as 1/t^2. The validity of the analytic description is confirmed by direct numerical solution of the full nonlinear equations of motion. The asymptotic forms of the wave profiles of the state variables are also found to occur in MRI simulations indicating that dissipation due to shocks plays a significant role apart from any effects arising from direct coupling to the turbulence

Detailed analysis of radiation data from the Gemini 4 and Gemini 7 proton-electron spectrometer experiments Final report, 13 Jun. 1967 - 30 Dec. 1968

Detailed analysis of radiation data from Gemini 4 and 7 proton-electron spectrometer experiment

Environmental group identification for upland rice production in central Brazil.

Upland rice (Oryza sativa L.) production is basically concentrated in four central Brazilian States, Mato Grosso, Goiás, Rondônia and Tocantins. To reduce the genotype and environment (G × E) interactions, the classification of environment groups was proposed. The goal of this study explores possibilities to adjust the upland rice regional breeding systems to optimally fit to the range of environments they are targeting, based on a historical yield data set of the Brazilian Geographic and Statistics Institute (IBGE, www.ibge.gov.br/home/) from 54 microregions. The specific objectives of this study were: (i) to identify and classify environmental groups in the Brazilian upland rice production area; (ii) to validate these environmental groups using yield data set from the upland rice multi-trial experiments (MTEs); (iii) and to identify the most representative site for each environmental group. For this the historical upland rice yield data from 54 microregions were detrented from the effects of technological advances and adjusted to the reference year, 2006. The adjusted yield data were used to build a matrix, which was submitted to a cluster analysis allowing the identification of three different environmental groups. These groups were classified as: highly favorable environment (HFE); favorable environment (FE); and less favorable environment (LFE). The HFE is less affected by inter-annual rainfall variability than the other two groups. The upland rice breeding programs must take into account the differences among the environmental groups to conduct their trials and suggest genotypes for the upland production area

Identification of mega environments in the Brazilian upland rice production area.

The goal of this study explores possibilities to adjust the upland rice regional breeding systems to optimally fit the range of environments they are targeting, based on a historical yield data set of the IBGE. The specific objectives of this study were: to identify and classify environment groups in the Brazilian upland rice (UPR) production area; to validate these environment groups using yield data set from the upland rice multi-trial experiments (MTEs); and to identify the most representative site for each environment group. For that, the historical upland rice yield data from 54 microregions were detrented from the effects of technological advances and adjusted to the reference year, 2006. A matrix was built with the adjusted yield data and submitted to a cluster analysis allowing to identify three different environment groups. These groups were classified as: high favourable environment (HFE); favourable environment (FE); and low favourable environment (LFE). The HFE has as characteristic being less affected by inter-annual rainfall variability than the other two. KEYWORDS: environment classification, cluster analysis, yield

Sensitivity as outcome measure of androgen replacement: the AMS scale

BACKGROUND: The capacity of the AMS scale as clinical utility and as outcome measure still needs validation. METHODS: An open post-marketing study was performed by office-based physicians in Germany in 2004. We analysed data of 1670 androgen-deficient males who were treated with testosterone gel. The AMS scale was applied prior to and after 3 months treatment. RESULTS: The improvement of complaints under treatment relative to the baseline score was 30.7% (total score), 27.3% (psychological domain), 30.5% (somatic domain), and 30.7% (sexual domain), respectively. Patients with little or no symptoms before therapy improved by 9%, those with mild complaints at entry by 24%, with moderate by 32%, and with severe symptoms by 39% – compared with the baseline score. We showed that the distribution of complaints of testosterone deficient men before therapy almost returned to norm values after 12 weeks of testosterone treatment. Age, BMI, and total testosterone level at baseline did not modify the positive effect of androgen therapy. We also demonstrated that the AMS results can predict the independent (physician's) opinion about the individual treatment effect. Both, sensitivity (correct prediction of a positive assessment by the physician) and specificity (correct prediction of a negative assessment by the physician) were over 70%, if about 22% improvement of the AMS total score was used as cut-off point. CONCLUSION: The AMS scale showed a convincing ability to measure treatment effects on quality of life across the full range of severity of complaints. Effect modification by other variables at baseline was not observed. In addition, results of the scale can predict the subjective clinical expert opinion on the treatment efficiency