Phase Analysis and Thermal Stability of Hot Isostatically Pressed Zirconia–Hydroxyapatite Composites

Composites of zirconia and hydroxyapatite (OHAp) have been processed via hot isostatic pressing (HIP) or sintering in air. When the composites were sintered in air at a temperature of 950°C, decomposition of the OHAp to tricalcium phosphate occurred. Using the HIP technique, composites without any detectable degradation of the OHAp phase were produced at 1200°C. The reactivity between zirconia and OHAp was dependent on both the amount of water lost from OHAp and the geometry of the interaction. The phase composition of the materials prepared was evaluated from their powder X-ray diffraction patterns, and their microstructures were studied via electron microscopy.     

Room-Temperature Solubility Behavior of Barium Titanate in Aqueous Media

In the present study, the incongruent dissolution of barium from barium titanate (BaTiO₃) has been studied as a function of dispersion pH and powder volume fraction for two different BaTiO₃ powders. In alkaline dispersions, the barium solubility strongly increases as the pH increases, as suggested by thermodynamic considerations. At pH <7, the barium solubility reaches a plateau, the height of which is dependent on the surface area of the powder and the solids loading of the slip. The BaTiO₃ surface is completely depleted of barium in this region.     

Lipid and Phospholipid Profiling of Biological Samples Using MALDI Fourier Transform Mass Spectrometry

Here we describe a study of the feasibility of lipid and phospholipid (PL) profiling using matrix assisted laser desorption/ionization (MALDI) Fourier transform mass spectrometry (FTMS) for two different applications. In this work PL profiles of different mammalian tissues as well as those of whole cell organisms were examined. In particular, comparative analysis of lipid and PL profiles of tissues from mice fed different diets was done and, in another application, MALDI FTMS was used to analyze PL profiles of genetically modified Saccharomyces cerevisiae. Computational sorting of the observed ions was done in order to group the lipid and PL ions from complex MALDI spectra. The PL profiles of liver tissues from mice fed different diets showed a cross correlation coefficient of 0.2580, indicating significant dissimilarity, and revealed more than 30 significantly different peaks at the 99.9% confidence level. Histogram plots derived from the spectra of wild type and genetically modified yeast resulted in a cross correlation coefficient 0.8941 showing greater similarity, but still revealing a number of significantly different peaks. Based on these results, it appears possible to use MALDI FTMS to identify PLs as potential biomarkers for metabolic processes in whole cells and tissues.     

Plasma desorption mass spectrometry, an analytical tool in protein engineering: characterization of modified insulins

Californium-252 plasma desorption mass spectrometry (PDMS) hasbeen employed for the characterization of a series of humaninsulin derivatives in order to evaluate the performance ofthis technique as an analytical tool in protein engineering.Several of the characterized modifications result in a 1 a.m.u.mass change. The precision in mass determination obtainableby PDMS analysis is not sufficient for unambiguous verificationof such modifications based on the molecular weight alone. Itis, however, possible to carry out in situ enzymatic digestionof the sample. Subsequent PDMS analysis will in most cases revealif the modification has been introduced as intended.     

Formation of Titanium Nitride Whiskers by Reaction of Sodium Titanium Bronze with Molten Sodium Cyanide

The production of titanium nitride, TiN, whiskers by reaction of sodium titanium bronze, Na_xTiO₂ (STB), with excess sodium cyanide, NaCN, at 1000°C is reported. The solubility of Ti from a STB in molten NaCN has been estimated experimentally. The TiN whiskers obtained under different experimental conditions have been examined by scanning electron microscopy and analyzed by analytical electron microscopy.     

Ionic Resistivity in Fused Silica: I, Conduction-History Effects

The steady-state dc ionic resistivity measurements on GE 124 commercial fused silica glass were carried cut in nonblocking mode between 300° and 650°C using fused Li⁺, Na⁺, and K⁺ nitrate salts as electrodes. The alkali ions were electrolyzed through a sample disk in a U-tube-type dc conductivity cell until steady state was achieved. Sequential conduction experiments at varying temperatures using various ions in a given sample showed that the resistivity of an ion could vary by as much as 1 order of magnitude depending upon the conduction history of the specimen, i.e., which ions had been electrolyzed through the specimen during prior experiments.     

Vergleich von Laser- mit Elektronenstrahlschweißen

Comparison of laser with electron beam welding . International industry requires products of the highest technical standards thus requiring application of the technologically most efficient and most economical processes. For this reason, the electron beam and laser welding processes are becoming more and more important. To provide a workpiece-relevant basis for deciding which technique should be used the following aspects will be investigated: generation of the beam, beam guidance systems, welding processes, application and power ranges, process controls, and equipment for industrial use. Finally a tabulated comparison should facilitate a detailed distinction between the two techniques.     

Verwertung von Klärschlamm

Gasification and pyrolysis of sewage sludges. Gasification and pyrolysis of sewage sludge were examined as alternatives to sewage sludge combustion. For this purpose, experimental gasification and pyrolysis tests were carried out with primary sewage sludge of Emschergenossenschaft. Main objective of these tests was the evaluation of yields and qualitites for products gained via sludge gasification or pyrolysis and an assessment of the environmentally relevant properties of the related residues. Both process alternatives enable the utilization of sewage sludge without any negative impact on the environment. Due to the total use of the organic components out of the sewage sludge in combination with an almost complete utilization resulting from the valuable hydrogen produced, gasification is an attractive alternative compared to the burning of sewage sludge, both from an environmental and an economic point of view. In the case of sewage sludge pyrolysis a portion of the organic components, however, will remain in the pyrolysis residue. Therefore, pyrolysis allows only a minor reduction of the residual product.