Interface between Quantum-Size-Effect Pb Nanocrystals and the Si(111)7 × 7 Substrate: an X-Ray Diffraction Study

In-situ X-ray diffraction is used to study the structure of Pb nanocrystalline islands grown on Si(111)7 × 7. The coverage dependence of the (0,8/7) surface reflection demonstrates that when the Pb nanocrystals nucleate, they consume the wetting layer. Concomitantly, the nanocrystals move away from the Si substrate and exhibit two-dimensional mosaicity in the substrate plane, while maintaining nearly perfect orientation in the direction perpendicular to the plane. These results, along with the fact that the nanocrystal interface is very smooth despite the highly corrugated substrate, indicate that the nanocrystals decouple from the Si substrate and provide an excellent interface to support electron standing waves that are needed for quantum-size effects (QSEs).     

Pathways to thin absorbers in CdTe solar cells

We present approaches to reduce the absorber thickness of CdTe solar cells. The investigations were done with CdTe absorber films deposited by the close-space sublimation (CSS) technique. Using these CdTe films, complete solar cells were produced in our own laboratory. The absorber thickness as the crucial parameter was varied between 1 and 11 µm in these experiments. It is analyzed how process steps following the CdTe layer deposition influence the structure of the absorber films as well as the solar cell properties. Three ways of back contact formation are compared. These include (i) the wet chemical etching of the CdTe surface, (ii) a plasma etching step, and (iii) the vacuum deposition of a thin intermediate copper layer. In the latter case, voids and shunts related to preferential etching at grain boundaries are avoided admitting the use of thinner absorber films. Thus, the solar-cell efficiencies were increased from below 9% to more than 10% while the CdTe film thickness was reduced from 11 µm to less than 4 µm.     

Functionalization of multi-walled carbon nanotubes with bis(2,2':6',2"-terpyridine) ruthenium(II)-connected diblock polymer

Multi-walled carbon nanotubes (MWCNTs) were functionalized with a bis(2,2':6',2"-terpyridine) ruthenium(ll)-connected diblock poly(N-isopropyacryamide) (RuTpyPNIPAM) by a simple methodology of covalent amidation. The composition and structure of the functionalized ruthenium multi-walled carbon nanotubes (RuMWCNTs) were characterized by thermogravimetric analysis, Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and scanning electron microscopy (SEM). These characterization methods confirm that after functionalization, ruthenium metallopolymer are interconnected or attached as aggregated structures on the surface of the carbon nanotubes.     

Towards robot cell matrices for agile production – SDU Robotics' assembly cell at the WRC 2018

ABSTRACT

To support shifting to high mix/low volume production, manufacturers in high wage countries aim for robotizing their production operations – with a special focus on the late production phases, where robotic assembly cells are then confronted with any complexities resulting from part and product varieties. The ‘World Robot Challenge 2018’ (WRC 2018) emulated such high mix/low volume production scenarios in a competition taking place in Tokyo, Japan. As part of our activities in SDU's newly founded I4.0 Lab, we integrated and advanced our experiences and developments from our various R & D projects in a novel robotic assembly cell design to compete in the WRC 2018. This article describes the system architecture as well as main aspects of its implementation regarding robot control, robot programming and computer vision and how they contributed to winning the challenge. Due to the application of collaborative robots, the cell design allows for operation without fences. Hence, multiple copies of the cell can be arranged in a highly reconfigurable, highly adaptable matrix structure in which several production flows can be handled concurrently. This concept was demonstrated by the installation of a duplicate cell that allowed for parallel developments on two cells and prolonged development also after shipping the first cell to Japan.     

Kinetics of nonisothermal recrystallization

The kinetics of recrystallization from nonisothermal cycles is modeled using an extension of the Arrhenius relationship. This model is used to predict the annealing response for both isothermal and nonisothermal annealing cycles. A nondimensional parameter called the “annealing index” is based on time and temperature and is related to the extent of anneal through physical properties. The effect of heating and cooling rate also can be quantified because the entire thermal cycle is evaluated. Nonisothermal anneals with heating rates of 10 and 100 °C/s were evaluated (along with isothermal anneals) for colddrawn ETP copper wire. A numerical solution is set forth to evaluate nonisothermal cycles. Formerly Research Assistant, Rensselaer Polytechnic Institute, Troy, NY, USA.     

Simulating the structural evolution of droplets following shell formation

Building on the new droplet drying framework developed by the authors in their previous work Handscomb et al., Chem. Eng. Sci. 64(4) 628–637 and Chem. Eng. Sci. 64(2) 228–246 this paper develops physically motivated criteria for dynamically deciding the appropriate structural sub-model to use at each stage of the drying process. Such criteria create a spatially resolved mechanistic droplet drying model which is capable of simulating multiple dried-particle morphologies based on evolving droplet composition and drying conditions. The new criteria are used in conjunction with the previously described model framework to simulate colloidal silica droplets, investigating the relationship between suspended particle size and dried-particle morphology.     

Relationship between magnesium intake and fecal magnesium excretion of ruminants

Twenty-four wethers were fed fresh cut orchardgrass, fertilized so that the magnesium concentration in the forage varied, and six lactating dairy cows were fed a 60% concentrate diet supplemented so that the magnesium concentration in the diet varied. This was to evaluate relationships between intake of magnesium and fecal excretion of magnesium in ruminants. Linear and logarithmic equations were evaluated for sheep and dairy cows. Although there was little difference between equations in ability to predict apparent absorption of magnesium at normal intakes of magnesium, the logarithmic equation was more useful for predicting magnesium apparent absorption at extreme intakes of magnesium. Constants for logarithmic equations for sheep and cows were similar; therefore, the data were combined and a single equation was derived for both species on the same logarithmic scale. Apparent absorption of magnesium in ruminants may be a function of the amount of magnesium consumed per unit of digesta surface area exposed to the rumen wall.     

Finite Element Simulation of Die Pressing and Sintering

Numerical simulation of die compaction and sintering is a promising tool for reducing development times and costs or optimizing production cycles. Finite element simulations allow qualitative and quantitative predictions of undesirable distortions after firing. Even qualitative predictions of crack formation are possible.     

Halogenlipide. II. Zur Synthese und massenspektrometrischen Charakterisierung von 2-O-Acyl-3-halogen-propan-1,2-diolen

Halogenolipids. II. Problems of Synthesis and Mass Spectrometric Characterization of 2-O-acyl-3-halogeno-propane-1,2-diols 3-Fluoro- and 3-chloro-2-O-palmitoyl-propane-1, 2-diol 2a, b were prepared by acylation of 3-fluoro- and 3-chloro-1-O-trityl-propane-1, 2-diol with palmitoyl chloride in pyridine and subsequent detritylation of the resulting 3-fluoro- and 3-chloro-2-O-palmitoyl-3-O-trityl-propane-1, 2-diol. 3-chloro-1, 2-di-O-palmitoyl-propane-1, 2-diol was deacylated enzymatically using pancreas lipase to give 3-chloro-2-O-acylpropan-1, 2-diol 2b . 2a and b both were unstable compounds which slightly isomerize — so under conditions of mass spectrometry — to give mixtures of 1- and 2-O-acyl-derivatives.     

Halogenlipide. I. Massenspektrometrische Strukturuntersuchung stellungsisomerer Fettsäureester der Halogenpropandiole (Desoxyhalogen-glyceride)

Halogenolipids. I. Mass Spectrometric Structure Investigation of the Isomeric Halogeno-propanediols Esterified with Fatty Acids (Deoxyhalogeno-glycerides) The mass spectrometric behaviour of the isomers of cytostatic effective halogeno-propanediols esterfied with fatty acids (deoxyhalogeno-monoglycerides and deoxyhalogeno-diglycerides) are investigated. The unambiguous structure of individual isomers is deduced from the characteristic fragmentation patterns of mass spectra. The synthesis of the mentioned compounds is described.