Die löslichkeitskonstanten der zinkhydroxidchloride-einbeitrag zur kenntnis der korrosionsprodukte des zinks

The solubilities of zinc hydroxychloride II and III have been studied at 25°C in solutionsof the constant ionic strength I = 0·2M. From experimental data the following values for equilibrium0842 constants are deduced: II:Zn(OH)_1,6 Cl_0,4: log[Zn²⁺] [Cl⁻]^10,4 [H⁺]^−1,6 = 8·22 ± 0,1 III: Zn(OH)_1,794 Cl_0,206: log[Zn²⁺] [Cl⁻]^0,206 [H⁺]^−1.794 = 9·84 ± 0,05. A value of K₁ = 6 ± 2 has been estimated for the equilibrium Zn²⁺ + Cl⁻ZnCl⁺. The relative stabilities of zinc hydroxychlorides and zinc hydroxides are represented with the aid of a predominance area diagram. Comparing recent data on the solubility of hydrozincite it is seen that zinc hydroxychlorides are not stable in natural waters.     

Vergleichende Glycerinbestimmungen im Wein nach der Jodid- und Kalkmethode

Ohne ZusammenfassungMitteilung aus den Laboratorien der Landes-Versuchsstation St. Michele a. E. und der Landes-Versuchsstation des Herzogtums Kärnten zu Klagenfurt.     

Low strain rate plasticity of continuously cast carbon steels

By a special plastometric method, the straightening operation of a vertically cast strand of two carbon steels was simulated. The temperature dependence of the low strain rate plasticity of both the steels examined is analogous although caused by very different reasons. As to the plain carbon steel, the amount of ferrite and its location is of prime importance, whereas in the case of eutectoid steel various modes of fracture and the influence of temperature on the relative plasticity of type II MnS inclusions are influencial. To avoid transverse cracking, it seems to be suitable to keep the strand at a rather high temperature (above 900 °C). Temperature cycling seems to be fundamental as to the structural changes taking place in the strand (grain size refining, ferrite fraction if any), whereas analogous influences of straining are more or less inexpressive. Of course, the results obtained are of quality only since the practical and laboratory conditions differ significantly. The knowledge obtained could be applied in regulating the intensity of strand cooling with the aim of lowering the waste portion and improving the surface quality of worked products.     

Magnetic force microscopy studies on the magnetic ordering in organic materials induced by high-energy proton irradiation

In this study, ferromagnetic microstructures in highly oriented pyrolytic graphite and superparamagnetic spots in polyimide foils were created by 2.25 MeV proton microbeam irradiation and characterized using atomic and magnetic force microscopy. For this purpose, graphite samples were irradiated with cross-like patterns of 15 μm × 15 μm size using ion fluences in the range of (0.003–2.5) × 10¹⁸ cm⁻². The irradiated crosses showed strong magnetic signals and a complex domain structure in the magnetic images depending on the geometrical dimensions of the crosses. Furthermore, polyimide foils were irradiated with microspots and fluences in the range of (0.016–3.1) × 10¹⁹ cm⁻². Magnetic force microscopy shows very strong phase shifts in these irradiated areas.     

Localization of the somatostatin sst2(a) receptor in human cerebral cortex, hippocampus and cerebellum

AIMS: To quantify birth prevalence and spectrum of congenital heart disease in the Island population of Malta, and compare these rates with previous studies. METHODS: All patients diagnosed as having congenital heart disease by echocardiography, cardiac catheterization, surgery or post-mortem by 1 year of age between 1990-1994 were included. There were 231 cases of live born congenital heart disease with a birth prevalence of 8.8/1000 live births. The commonest lesions were ventricular septal defect, pulmonary stenosis and tetralogy of Fallot. The rates of individual lesions were compared with two recent epidemiological studies with similar methodologies. RESULTS: Although the overall birth prevalence of congenital heart disease was similar in three studies, significantly higher rates of pulmonary stenosis, tetralogy of Fallot and double outlet right ventricle were found in Malta, all of which predispose to right ventricular outflow tract obstruction. In contrast, there were lower rates of lesions causing left ventricular outflow tract obstruction. A higher rate of ventricular septal defect was also found. The Maltese gene pool may contain an inherent predisposition towards lesions causing right ventricular outflow tract obstruction.     

Nanokomposite für die Herstellung oxidischer Matrices keramischer Faserverbundwerkstoffe

Nanocomposites for the preparation of oxide/oxide ceramic matrix composites Ceramic suspensions for the fabrication of ceramic matrix composites are usually produced from submicron powders. Taking the electrophoretic infiltration of Nextel? 720‐ and Nextel? 650‐ fabrics as an example, it is shown that the use of nanopowders and nanocomposites can be advantageous for the preparation of matrices, too. Coinfiltration of submicron α‐alumina and a second nanoscale phase (zirconia) allows the preparation of a (α‐alumina + zirconia) structural composit matrix. Functional nanocomposites of alumina and silica facilitate the formation and densification of mullite at temperatures below the the maximum temperature for short‐term heat treatment of the reinforcement fibre.     

Pattern synthesis for TechSat21 - a distributed space-based radar system

The TechSat21 space-based radar employs a cluster of free-floating satellites, each of which transmits its own orthogonal signal and receives all reflected signals. The satellites operate coherently at the X band. The cluster forms essentially a multielement interferometer, with a concomitantly large number of grating lobes and significant ground clutter. A novel technique for pattern synthesis in angle-frequency space is proposed, which exploits the double periodicities of the grating lobes in the angular domain and of the radar pulses in the frequency domain, and allows substantial gains in clutter suppression. Gains from 7 to 17 dB relative to the normal random, sparse array appear feasible.     

On the design of the tubesheet and the tubesheet-to-shell junction of a fixed tubesheet heat exchanger

For the (mechanical) design of an existing fixed tubesheet heat exchanger, a C2-Hydrogenation reactor in a petrochemical plant, various code solutions are compared with each other and with a Finite Element solution based on the Direct Route in Design by Analysis (EN 13445-3, Annex B). The codes and standards used in the investigation are ASME Section VIII, Division 1 and EN 13445-3, Clause 13 and Annex J.