Transfer doping of diamond: Buckminsterfullerene on hydrogenated, hydroxylated, and oxygenated diamond surfaces

A monolayer of buckminsterfullerene (C₆₀) has been modelled on hydrogenated, hydroxylated (–OH-terminated), and oxygenated diamond surfaces using ab-initio, density-functional-theory calculations, with a view to assessing the likelihood of transfer doping in each case. The C₆₀ layer is predicted to spontaneously extract electrons from the hydrogenated surface, although on the hydroxylated surface there is an energy gap of ∼1 eV preventing a similar electron transfer. With the fully oxygenated surface, there is a gap to electron transfer of ∼4 eV, effectively prohibiting the transfer-doping effect. In each case, the molecule causes only very little disturbance to the substrate, although chemical reaction remains a significant possibility.     

A new systematic classification of influences on thermal production processes for mechanical simulations

For process–structure simulation, a lot of models and methods have been created and implemented into different software systems. The uncontrolled growth of specific solutions has led to a bewilderment for (potential) users during the last years. Therefore, the most important step before choosing and applying a method for modeling is to define the task of each simulation clearly and, in addition, to analyze the general conditions. In this paper, a systematic classification of all relevant influences for a part-specific simulation by means of the Finite Element Method (FEM) concerning thermal production processes is presented. Relating to a certain scenario, this classification helps to choose adequate models. Combined with the experience and the theoretical background of the user, the dilemma of efficiency in application and the accuracy of the results can be solved satisfactorily for each task. This paper is based on investigations within the scope of the Transregional Collaborative Research Center/ TR 10 and is kindly supported by the German Research Foundation (DFG).     

Effects of the level of feed intake and ergot contaminated concentrate on ergot alkaloid metabolism and carry over into milk

The aim of the present study was to examine the effects of ergot contaminated concentrate at differing levels of feed intake on ergot alkaloid metabolism and carry over into milk. Twelve double fistulated (in the rumen and the proximal duodenum) Holstein Friesian cows were fed either the control diet (on a dry matter (DM) base: 60% maize silage, 40% concentrate) or the contaminated diet (concentrate contained 2.25% ergot, which caused an alkaloid concentration of the daily ration between 504.9 and 619.5 μg/kg DM) over a period of 4 weeks. Daily feed amounts were adjusted to the current performance which resulted in a dry matter intake (DMI) variation between 6.0 and 18.5 kg/day. The actual alkaloid exposure varied between 4.1 and 16.3 μg/kg body weight when the ergot contaminated concentrate was fed. Approximately 67% of the alkaloids fed were recovered in the duodenal ingesta, and ～?24% were excreted with the faeces. No alkaloid residues could be detected in the blood or milk samples.     

Effect of coating on cleanability of glazed surfaces

The aim of this study was to establish the effects of different coatings on the cleanability of glazed ceramics. The surface properties were examined with a contact angle meter, a contact profilometer and a confocal microscope. The surfaces were soiled with three radiochemical model soils: inorganic particle soil, organic particle soil and oil soil. Soil adhesion on surfaces was measured with a quantitative radiochemical procedure. Generally, cleanability of the particles present in the model soil was found to be affected by the roughness of the surfaces; however, the cleanability of the oil in the model soils correlated with the contact angle of water on the surfaces. Coating of glazes, especially with fluoropolymer film, generally increased the contact angle values. The coatings affected the cleanability of ceramics somewhat: particle soils were removed most efficiently from glazes coated with TiO₂ and Zr. By contrast the oil soil residues of the fluoropolymer surfaces were the lowest. The cleanability results of the three model soils based on inorganic or organic particles or oil were different indicating differences between the cleanabilities of these main components of the soils.     

Flow physics and Stokes’ theorem in wind turbine aerodynamics

A viscous lift theorem is derived from a momentum balance and Stokes’ theorem around one section of a wind turbine blade. The theorem is a generalization of the classical Kutta–Zhukovsky lift theorem for the viscous near-field and is validated for 2-D attached and separated flow. The application of the viscous lift theorem within a coupled Navier–Stokes/vortex-panel solver gives insight into the complex 3-D aerodynamics pertinent to wind turbines.     

Solving probabilistic multi-facility Weber problem by vector quantization

The multi-facility Weber problem is concerned with locating in the plane m facilities having unlimited capacities and allocating them to n customers at minimum total cost. The deterministic version is a non-convex optimization problem and difficult to solve exactly. In this work we focus on a probabilistic extension and consider the situation where the customer locations are randomly distributed. For this problem, we propose new heuristics based on the principle of vector quantization which are capable of computing good quality solutions for general distance functions and customer location distributions.     

Frequency Selective Characteristics of a Plasma Layer with Sinusoidally Varying Electron Density Profile

In this study reflection, absorbtion and transmission characteristics of a plasma layer having sinusoidally varying electron number density are analysed. In the analysis, plasma layer is divided into thin subslabs with constant electron number densities. The general frequency selective behavior of the plasma is investigated by varying the plasma parameters, external magnetic field excitation and sinusoidal electron distribution in order to be used in recent plasma applications.     

Synthesis and crystal structure of dinuclear [(thf)3YCl2{μ-P(H)C6H2-2,4,6-Me3}]2 with seven-coordinate yttrium atoms

The metathesis reaction of KP(H)Mes with YCl₃ in tetrahydrofuran yields dinuclear [(thf)₃YCl₂{μ-P(H)Mes}]₂ (1) with a yield of 26% (Mes = mesityl, C₆H₂-2,4,6-Me₃). The seven-coordinate yttrium atoms exhibit pentagonal bipyramidal coordination spheres with bridging mesitylphosphanide substituents. The Y₂PC fragments are nearly planar with an average Y–P bond length of 296.0 pm. The P-bound hydrogen atoms are perpendicular to these planes. The small ¹J(P,H) coupling constant of 125 Hz is in agreement with the picture that the H atom binds mainly to the p-orbital of the phosphorus atom.     

Alkali deactivation of high-dust SCR catalysts used for NOx reduction exposed to flue gas from 100 MW-scale biofuel and peat fired boilers: Influence of flue gas composition

Deactivation of vanadium–titanium deNO_x SCR (selective catalytic reduction) catalysts in high-dust position have been investigated in three 100 MW-scale boilers during biofuel and peat combustion. The deactivation of the catalyst samples has been correlated to the corresponding flue gas composition in the boilers. Too investigate the effect on catalyst deactivation a sulphate-containing additive was sprayed into one of the furnaces. Increased alkali content on the SCR catalyst samples decreased the catalytic deNO_x activity. The study has shown a linear correlation between exposure time in the boilers and alkali concentration (mainly potassium) on the samples. The results imply that mainly alkali in ultra fine particles (<100 nm) in the flue gas increased the alkali accumulation on the catalyst samples. Low correlation was found between particles larger than 100 nm and the catalyst deactivation. It was not possible to decrease the deactivation of the catalyst samples by the sulphate-containing additive. Although the additive had an effect in sulphating potassium chloride to potassium sulphate, it did not decrease the amount of potassium in ultra fine particles or the deactivation of the catalyst samples.