Solubility of Si3N4 in Liquid SiO2

The nitrogen solubility in the SiO₂-rich liquid in the metastable binary SiO₂-Si₃N₄ system has been determined by analytical TEM to be 1%–4% of N/(O + N) at 1973–2223 K. Analysis of the near edge structure of the electron energy loss peak indicates that nitrogen is incorporated into the silicate network rather than being present as molecular N₂. A regular solution model with a positive enthalpy of mixing for the liquid was used to match the data for the metastable solubility of N in the presence of crystalline Si₃N₄ and to adjust the computed phase diagram. The solubility of Si₃N₄ in fused SiO₂ is far less than reported in liquid silicates also containing Al, Mg, and/or Y. Apparently, these cations act as modifiers that break anion bridges in the silicate network and, thereby, allow further incorporation of Si₃N₄ without prohibitive amounts of network cross-linking. Finally, indications emerged regarding the diffuse nature of the Si₃N₄-SiO₂ interface that leads to amorphous regions of higher N content.     

High-Throughput Experimentation in Oxidation Catalysis

High-throughput experimentation in catalysis comprises the following components: (i) automated high-throughput synthesis, (ii) testing in Stage I and Stage II, for which to some extent novel assays are necessary, (iii) data handling and experimental design tools, and (iv) robotics. This contribution covers these topics, using examples from the research of the authors, but also from the literature, in order to illustrate the problems and opportunities associated with high-throughput experimentation in catalysis, focusing particularly on heterogeneous catalysis.     

Five-year experience with setup and implementation of an integrated database system for clinical documentation and research

In radiation oncology, where treatment concepts are elaborated in interdisciplinary collaborations, handling distributed, large heterogeneous amounts of data efficiently is very important, yet challenging, for an optimal treatment of the patient as well as for research itself. This becomes a strong focus, as we step into the era of modern personalized medicine, relying on various quantitative data information, thus involving the active contribution of multiple medical specialties. Hence, combining patient data from all involved information systems is inevitable for analyses. Therefore, we introduced a documentation and data management system integrated in the clinical environment for electronic data capture. We discuss our concept and five-year experience of a precise electronic documentation system, with special focus on the challenges we encountered. We specify how such a system can be designed and implemented to plan, tailor and conduct (multicenter) clinical trials, ultimately reaching the best clinical performance, and enhancing interdisciplinary and clinical research.     

Silphinene Sesquiterpenes as Model Insect Antifeedants

Silphinene sesquiterpenes are established chrysomelid antifeedants. In this work, nine silphinene analogs, 11-acetoxy-5-angeloyloxysilphinen-3-one (1), 11-acetoxy-5-tigloyloxysilphinen-3-one (2), 11-acetoxy-5-iso- butyryloxysilphinen-3-one (3), 11-hydroxy-5-angeloyloxysilphinen-3-one (4), 11,5-dihydroxysilphinen-3-one (5), 11,5-diacetoxysilphinen-3-one (6), 5,11-diisobutyryloxysilphinen-3-one (7), silphinen-3,5,11-trione (8), and O-methyl-5-epicantabrenolic acid methyl ester (10), and a presilphiperfolane sesquiterpene (9) were tested against several divergent insect species, including the lepidopteran Spodoptera littoralis, the chrysomelid Leptinotarsa decemlineata, and five aphid species, and their antifeedant effects were compared with those of picrotoxinin, a GABA-antagonist, and thymol, an allosteric modulator for insect GABA receptors. All insects tested responded to at least one silphinene analog and/or GABA antagonist. Compound 3 and thymol were effective antifeedants against all species tested except S. littoralis, with varying potencies according to their feeding ecologies. The toxicity of these compounds was species-dependent and did not correlate with their antifeedant effect.     

Untersuchung des einflusses molekularer parameter auf morphologie und eigenschaften von polyethylenen niedriger dichte

Based on the example of PE-LD grades and on model substances obtained by preparative fractionation (fractions in the molecular weight range M?_w = 1.2 ? 390·10⁴ g/mol), comprehensive investigations regarding the problems of structure/properties have been carried out. The correlations of M?_w with 15 physical and application technological perameters have been investigated taking into account the reaction mechanism during the manufacturing of PE-LD in the tubular and agitated autoclave reactor, resulting in the formation of so-called primary structure perameters M?_n, M?_w, molar mass distribution, short chain branching and long chain branching. For the interpretation of the results, among other factors, also the morphological conditions have been taken into consideration, which in connection with the molecular parameters reveal — for specific M?_w-ranges — strong changes and saturation ranges, resp., for the physical and application technological properties.     

High-Temperature Electrical Properties in the ThO2-Rich Region of ThO2-RE2O3 Systems

In the present study the n -type electronic conduction in terms of the parameter p e, and the phase relations in several ThO₂-RE2O₃ systems were examined. Large fluorite solid solution regions exist at elevated temperatures. It was demonstrated that RE₂O₃-doped thoria compositions feature lower parameters p e, and higher chemical stability than the conventional stabilized ZrO2 electrolytes. The results are given in terms of the characteristic parameter p e, in the temperature range from 1000° to 1600°C. The experimental investigations were made using a new thermodynamic measuring system.     

Practical Significance,Theory and Determination of Compatibility of Dyes on Synthetic-polymer Fibres

The compatibility of dyes is particularly important in regard to the time, reproducibility and levelness of dyeing. For basic dyes on acrylic fibres and anionic dyes on nylon, a characteristic of the dye—the compatibility value K— is valuable in determining whether it can be used in the same bath as others. Dyes having the same K-value are compatible under most dyeing conditions. For disperse dyes, K-values do not exist. In selecting such dyes for use together, other properties of the dyes and the concentrations to be used in the particular combination must be considered.     

Kinetic investigations in heterogeneous reaction systems by wavefront analysis

In this paper the previously introduced wavefront analysis is extended to heterogeneous reaction systems, which consist of several reaction steps. It is shown how three mainly informations obtained at the wavefront, namely the damping of the wavefront, the time-gradients at the wavefront and the propagation velocity of the wavefront, can be used for kinetic investigations of a reaction step under consideration.     

The Effect of processing on the content and composition of free sterols and sterol esters in soybean oil

The content and composition of free sterols and sterol esters in crude soybean oil and in oils from different stages of two continuous refining systems were determined. The sterols were isolated by preparative thin layer chromatography and analyzed by gas chromatography with cholesterol as an internal standard. The free sterols in one of the degummed oils amounted to 3.1 mg/g and were diminished to 1.8 mg/g oil by the De Laval Short-Mix refining process. The content of free sterols of the other degummed oil was reduced from 3.4 to 1.6 mg/g oil by the Zenith process. The greatest reduction of sterol content was caused by the treatment with bleaching earth. The sterol esters accounted for 0.6 mg/g of the degummed oil, and only very small changes were observed during the processes. However, changes in the composition of fatty acids of the sterol esters were found. These changes might indicate a selective deacylation of sterol esters or an interesterification during the refining processes. The composition of sterols in free and esterified form were different. Campesterol, stigmasterol and sitosterol were obtained in both free and esterified form, but Δ7 stigmasterol was only found in esterified form. Only small changes in the percentage distribution of the sterols occurred during the processes. Present adress Food Technology Division, ALFA-LAVAL,S-14700 Tumba, Sweden