Hydrogen and oxygen on a /110/ nickel surface

Hydrogen-oxygen reaction on nickel surface, electron diffraction stud

Ammonia adsorption and decomposition on a tungsten /211/ surface

Ammonia adsorption and decomposition on tungsten 211 surface studied by mass spectrometry, electron diffraction, and changes in work functio

First steps in the oxidation of a /110/ nickel surface

Initial steps in oxidation of nickel surface studied using low energy back-reflection electron diffractio

In-situ-Vergleichstest für Sensoren zur Matrixpotentialmessung

Wassergehalt und Matrixpotenzial sind zentrale bodenhydrologische Zustandsvariablen. Zur in-situ Messung dieser Größen im Freiland bietet der Markt eine zunehmende Vielzahl von konkurrierenden Systemen und Technologien an. Zur Messung des Matrixpotentials existiert allerdings bis heute kein Sensorsystem, das mit Zuverlässigkeit und Genauigkeit das Matrixpotential über den gesamten Feuchtebereich messen kann. Zur Prüfung der Messcharakteristik von Bodenfeuchtesensoren hat ein Konsortium von 10 Institutionen im Jahr 2016 über mehrere Monate eine Vergleichsstudie auf einer homogenisierten Testfläche durchgeführt. Die Fläche war ca. 60 m2 groß, natürlichen meteorologischen Bedingungen ausgesetzt und wurde von Vegetation freigehalten. In einem Raster von 0,5 m Weite wurden 15 verschiedene Systeme zur Messung der Bodenfeuchte und 13 verschiedene Systeme zur Messung des Matrixpotenzials in jeweils vierfacher Wiederholung in 0,2 m Tiefe installiert. In diesem Beitrag sollen spezifisch die Ergebnisse der Matrixpotentialmessungen diskutiert werden, deren Technologie auf direkter Druckmessung (Tensiometer T4, T5, T8 der Fa. UMS), Messungen der dielektrischen Eigenschaften (MPS-1, MPS-2 und MPS-6 der Fa. Decagon Devices) bzw. Messungen der Wärmedissipation (pF-Meter, TensioMark der Fa. EcoTech) beruhen. Wir diskutieren die Ergebnisse hinsichtlich der absoluten Lage und Variabilität der Signale, der Reaktionszeiten auf schnelle Feuchteänderungen und auf Temperaturschwankungen. Die Studie zeigte ferner, wie komplex die Probleme einer Vergleichsstudie im Feld generell sind. Trotz großer Sorgfalt bei der Versuchsanlage konnte z.B. die Homogenitätsannahme nur für eine initiale Periode von wenigen Wochen aufrecht gehalten werden. Ein Starkregenereignis mit Infiltrationsüberschuss führte zur Bildung von Bodenkrusten und oberflächlichen Umverteilungsnetzwerken, und damit zu kleinskaliger Heterogenität der oberen Randbedingung. Generell wirft dies Fragen auf in Hinblick auf die Aussagekraft einzelner Sensorenwerte in Freilandstudien

Hadronic production of bottom-squark pairs with electroweak contributions

We present the complete computation of the tree-level and the next-to-leading order electroweak contributions to bottom-squark pair production at the LHC. The computation is performed within the minimal supersymmetric extension of the Standard Model. We discuss the numerical impact of these contributions in several supersymmetric scenarios.Comment: 33 pages, v2: preprint numbers correcte

Evaluation of Cathode Gas Composition and Temperature Influences on Alkaline Anion Exchange Membrane Fuel Cell (AAEMFC) Performance

The effects of different temperatures (55, 65, 75 and 85 °C) and cathode gas compositions (O2, synthetic air, air and 90% synthetic air+10% CO2) on alkaline anion exchange membrane fuel cell (AAEMFC) were evaluated. Membrane electrode assemblies (MEA) were fabricated using commercial anion exchange membrane (AEM) in OH- form and Pt catalyst. Polarization curves and voltage responses during constant current were performed in order to describe the influences of temperature and gas composition on the AAEMFC performance. The experimental results showed that the fuel cell performance increases with elevating temperatures for all applied gas compositions. Highest power density of 34.7 mW cm-2 was achieved for pure O2 as cathode feed. A decrease to 20.3 mW cm-2 was observed when cathode gas composition was changed to synthetic air due to reduction of the O2 partial pressure. The presence of CO2 in atmospheric air applied to the cathode stream caused a further drop of the maximum power density to 15.2 mW cm-2 driven by neutralization of OH- ions with CO2

Particle-in-cell simulations of rf breakdown

Breakdown voltages of a capacitively coupled radio frequency argon discharge at 27 MHz are studied. We use a one-dimensional electrostatic PIC code to investigate the effect of changing the secondary emission properties of the electrodes on the breakdown voltage, particularly at low pd values. Simulation results are compared with the available experimental results and a satisfactory agreement is found.Comment: 12th International Congress on Plasma Physics, 25-29 October 2004, Nice (France

Optimizing of preoperative computed tomography for diagnosis in patients with peritoneal carcinomatosis

<p>Abstract</p> <p>Background and Objective</p> <p>This study evaluates whether Computer Tomography is an effective procedure for preoperative staging of patients with Peritoneal Carcinomatosis.</p> <p>Method</p> <p>A sample of 37 patients was analyzed with contrast enhanced abdominal Computer Tomography, followed by surgical staging. All Computer Tomography scans were evaluated 3 times by 2 radiologists with one radiologist reviewing 2 times. The efficacy of Computer Tomography was evaluated using the Spearman correlation coefficient. Correlations were analyzed by abdominopelvic region to assess results of the Peritoneal Carcinomatosis Index (PCI) aggregating the 13 regions. Surgical findings were compared to radiological findings.</p> <p>Results</p> <p>Results indicate high correlations between the surgical and radiological Peritoneal Carcinomatosis Indices. Analyses of the intra-class correlation between the first and second reading of one radiologist suggest high intra-observer reliability. Correlations by abdominopelvic region show higher values in the upper and middle regions and relatively lower values in the lower regions and the small bowel (correlation coefficients range between 0.418 and 0.726, p < 0.010; sensitivities range between 50% and 96%; and specificities range between 62% and 100%).</p> <p>Conclusion</p> <p>Computer Tomography represents an effective procedure in the preoperative staging of patients with PC. However, results by abdominopelvic region show lower correlation, therefore suggest lower efficacy. These results are supported by analyses of sensitivity and accuracy by lesion size. This suggests that Computer Tomography is an effective procedure for pre-operative staging but less for determining a tumor's accurate extent.</p

Global assessment of manure management policies and practices

In 2014 an assessment of livestock manure policies was performed in 34 countries in Asia, Africa and Latin America, followed by an in-depth assessment of manure management practices in Bangladesh, Viet Nam, Ethiopia, Malawi, Argentina and Costa Rica. The assessments revealed the key barriers for improving integrated manure management and identified six opportunities for actual practice changes to improve manure related policies as well as farm practices with the overall objective of improving food security while mitigating methane emissions at the same tim

Hadronic production of squark-squark pairs: The electroweak contributions

We compute the electroweak (EW) contributions to squark--squark pair production processes at the LHC within the framework of the Minimal Supersymmetric Standard Model (MSSM). Both tree-level EW contributions, of O(alpha_s alpha + alpha^2), and next-to-leading order (NLO) EW corrections, of O(alpha_s^2 alpha), are calculated. Depending on the flavor and chirality of the produced quarks, many interferences between EW-mediated and QCD-mediated diagrams give non-zero contributions at tree-level and NLO. We discuss the computational techniques and present an extensive numerical analysis for inclusive squark--squark production as well as for subsets and single processes. While the tree-level EW contributions to the integrated cross sections can reach the 20% level, the NLO EW corrections typically lower the LO prediction by a few percent.Comment: 36 pages, 18 figure