Untersuchungen an Alkylmetallalkoxiden der Elemente Aluminium,Gallium und Indium. III. Eigenschaften und Schwingungsspektren von Dialkylgallium- und Indiumalkoxiden

Studies on Alkyl Metal Alkoxides of Aluminium, Gallium, and Indium. III. Properties and Vibrational Spectra of Dialkylgallium- and Indium Alkoxides The preparation and the properties of dialkyl metal alkoxides R₂MOR′ (with R = CH₃, CD₃, C₂H₅; R′ = CH₃, CD₃ and M = Ga, In) are described. The vibrational data (IR and Raman) of the trimeric methyl derivatives point to puckered six-membered M₃O₃-ring systems.     

Phenazine, 3. Mitt.: N-(o-Aminophenyl)-benzo[a]phenazin-5-amin, das vermeintliche “Dihydronaphthodiphenazin”Kehrmanns, und seine Derivate

The dihydronaphthodiphenazine ofKehrmann, which is according toBadger andPettit reported to be 14-o-aminophenyl-13,14-dihydro-5,8,13,14-tetraaza-6,7-benzopentaphene, is N-(o-aminophenyl)-benzo[a]phenazin-5-amine. This was proved by chemical and spectroscopic investigations. The structures of the derivatives prepared byBadger andPettit are also corrected and the acetylation processes are cleared up.     

The effect of the ammonium paratungstate source on the tungsten crystallite size

In an investigation into the effects of CaCl₂ on the sulfation of limestones in a laboratory furnace simulating fluidized-bed coal combustion conditions, small additions of CaCl₂ (<1 mole%) to the limestone prior to calcination were found to increase the extent of sulfation by changing the limestone pore structure. These changes were effected by trace amounts of liquid in the system in a synthetic SO₂/O₂ flue gas at 850°C. At much higher concentrations of CaCl₂, large amounts of a liquid phase are produced, containing a substantial quantity of dissolved CaO and leading to greatly enhanced sulfation when exposed to SO₂/O₂. The use of CaCl₂ additive in fluidized-bed combustion would reduce the quantity of limestones required to meet air pollution standards for SO₂ and also reduce the quantity of solid waste generated.     

Nets and generalized quadrangles

There is a new method of constructing generalized quadrangles (GQs) given by S. Löwe, which is based on covering of nets; all GQs with a regular point can be represented in this way. Here we give a method of constructing GQs with a regular point using the so-called content functions on nets. In the last part of the paper we lay the foundations for a research project aiming to use the more general notion of content to classify GQs and maybe to construct new ones.Both authors acknowledge the financial support by CRUI and DAAD in the frame of Programma Vigoni, which made this work possible.     

Low-temperature transport properties of UCu5

The electrical resistivity (T) and the thermal conductivity (T) have been measured for UCu₅ in the temperature range between 0.02 and 20 K. Two distinct anomalies in (T) are due to previously established phase transitions at approximately 15 and 1 K, respectively. They indicate considerable changes in the electronic structure of this compound, implying sizeable truncations of the Fermi surface with decreasing temperature at both transitions. In almost the entire covered temperature range the thermal conductivity is dominated by phonon contributions. Its temperature dependence is fairly well reproduced by a calculation considering phonon scattering by electrons and by point defects. At very low temperatures, asT approaches 0 K, the Wiedemann-Franz law _e L ₀ T, where _e is the electronic part of (T) andL ₀ is the Lorenz number, is almost perfectly fulfilled.