Bestimmung von Melment in Zementmischungen durch UV-Spektralphotometrie

Ohne Zusammenfassung

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Determination of melment in cement mixtures by UV-spectrophotometry

     

Der Dreistoff: Vanadium-Silicium-Germanium

Zusammenfassung V-Si-Ge-Legierungen werden aus den Komponenten hergestellt und röntgenographisch untersucht. V₃Si und V₃Ge bilden eine lückenlose Mischreihe. Ebenso gehen die T1-Phasen V₅Si₃ und V₅Ge₃ homogen über, was auch für die C-stabilisierten Phasen mit teilweise aufgefüllter Mn₅Si₃-Struktur gilt. V₁₁Ge₈ löst praktisch kein Silicid und steht mit V₅(Si, Ge)₃ und (Ge, Si)-Mischkristall im Gleichgewicht. Im Disilicid erfolgt ein Si/Ge-Austausch bis etwa 11 (1000°C Homogenisierungstemp.). Bei dieser Temp. tritt nach kurzen Glühzeiten das sogenannte Digermanid (V₁₇Ge₃₁) noch nicht in Erscheinung.

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V-Si-Ge-alloys have been prepared out of the components and examined. V₃Si and V₃Ge do form a contineous solid solution, the same is true for V₅Si₃ and V₅Ge₃ either for the W₅Si₃-structure or for the carbon stabilized Mn₅Si₃-type phases. V₁₁Ge₈ does not dissolve any silicide. There are equilibria between V₁₁Ge₈, V₅(Si,Ge)₃ and a (Ge, Si)-solid solution. Silicon can be substituted by germanium in VSi₂ up to 11 (1000°C homogenizing temperature). At this temperature the so called digermanide (V₁₇Ge₃₁) does not occur after a short anneal.

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Mit 1 Abbildung     

Low-temperature infrared and raman studies: XI. The vibrational behaviour of ammonium perchlorate- its phase changes and the rotational freedom of its ions

An infrared, Raman and X-ray diffraction study on NH₄CIO₄. was conducted in the temperature ranges 300 to 17 °K, 300 to 130 °K and 300 to 120 °K respectively. The infrared studies also included the deuterated salt. The spectra are discussed and vibrational assignments made. Changes in the infrared spectra, as well as intensity measurements of the vibrational bands indicate anomalous behaviour in the region 100–110 °K as well as 17–50 °K. Possible reasons for these changes are proposed. The rotational behaviour of the ammonium ion upon cooling and hydrogen bonding are discussed.     

Koordinationschemische Untersuchungen an Zinkdialkylen. X. Über die Reaktion von Zinkdimethyl mit sekundären Aminen

Dimethyl zinc reacts with diethyl amine, piperidine and morpholine forming definite 1:2- or 1:1-complexes. The weaker basic secondary amines pyrroline, pyrazolidine and imidazoline cause the evolution of methane and the formation of the corresponding zinc amides. In this way zinc pyrrolide, zinc pyrazolide and zinc imidazolide were obtained in form of pure substances.     

Spektralphotometrische Bestimmung von Spurenelementen der Schwefelwasserstoffgruppe mit Natriumpyrrolidindithiocarbamidat

Zusammenfassung Es wird eine direkte, photometrische Bestimmungsmethode für Kupfer in Eisenwerkstoffen mit Natriumpyrrolidindithiocarbamidat beschrieben. Nach Auflösen der Probe wird der Cu-PyDTC-Komplex in Anwesenheit von Maskierungsmitteln mit Tetrachlorkohlenstoff extrahiert und photometriert. Die Methode ist der Kupferbestimmung mit Diäthyldithiocarbamidat durchaus gleichwertig, das Na-PyDTC besitzt aber gegenüber dem DDTC den Vorteil größerer Anwendungsbreite, da es auch im sauren Gebiet verwendbar ist. Gegenüber anderen bekannten Bestimmungsverfahren bietet die beschriebene Arbeitsweise den Vorteil größerer Schnelligkeit bei gesteigerter Genauigkeit und Reproduzierbarkeit.

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Summary A direct photometric method is described for the determination of copper in ferrous material with sodium pyrrolidinedithiocarbamate (Na-PyDTC). After dissolution of the sample the Cu-PyDTC complex is extracted with carbon tetrachloride in presence of masking agents and is determined by photometry. The method can be favourably compared to the determination of copper with diethyldithiocarbamate (DDTC), yet Na-PyDTC is superior to DDTC with regard to the range of applicability as it can be used also in acid medium. In contrast to other methods already known the recommended procedure permits more rapid determinations of increased accuracy and reproducibility.

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IV. Mitt.: Kovács, E., H. Guyer u. W. Lüscher: diese Z. 208, 321 (1965).

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Kovács, E.; Produktions A.G. Meilen (Schweiz); H. Guyer, Hilger and Watts Ltd., German Office, Dortmund (Deutschland)

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Der Direktion der Georg Fischer Aktiengesellschaft, Schaffhausen (Schweiz), danken wir für die Bewilligung zur Veröffentlichung der vorstehenden Arbeit. Herrn W. Lüscher danken wir für die Ausführung der zahlreichen Extraktionen und photometrischen Messungen.     

The ETACS European project for testing the comparability of sensors and analysers

ETACS is the official acronym for the European project "European Testing and Assessment of Comparability of On-line Sensors/Analysers". This project has three main objectives to achieve the comparability of performance data for sensors and analysers in the environmental field. First, to develop a test protocol for validation and comparison of the performance of on-line sensors/analysers. The test protocol is intended to be generic, that is independent of the specific sensors/analysers and the specific parameters to be monitored. Second, the practical testing of this test protocol to assess its applicability and to develop the techniques used. Finally, to achieve widespread acceptance of the test protocol by producer/suppliers, users and relevant authorities to assist its early adoption as an agreed European standard. Laboratory tests for producing the test protocol have been carried out and completed to check the applicability of such a protocol.     

Salting-in of alcohols in aqueous solutions by tetraalkylammonium bromides at the freezing temperature

The freezing-point depression of the ternary systems tetraalkylammonium bromides-t-butanol-water for the first five homologs of R₄NBr was measured. In the case of Bu₄NBr, the effect of size of the alcohol (methahol ton-butanol) was also investigated. From the corresponding freezing-point data for the binary systems the apparent salting constants were calculated. The true salting constantsk _s were obtained by extrapolation to infinite dilution. These are all very close to zero at the freezing temperature. From the corresponding thermochemical data the temperature dependence ofk _s was calculated, and above 5°C all the R₄NBr salts int-butanol; the salting-in increases with temperature and with the size of the hydrophobic cations. The scaled-particle theory is at present the only one which can account semiquantitatively for the temperature dependence of the salting-in effect. On leave of absence from Chemistry Department, The University, Sheffield S3 7HF, England To whom correspondence should be addressed.     

Neopentylallylsodium

Neopentylallylsodium (NpANa) has been prepared by the reaction of neopentylallyllithium with an equivalent amount of sodium 2,2-dimethyl-1-butoxide in hydrocarbon solvent. NpANa is stable in diethyl ether and THF solvents for extended periods of time, and proton NMR and UV data are reported for NpANa in THF at various temperatures. A more substantial degree of ionic delocalization is indicated for NpANa as compared to NpALi and apparently is greater for the trans isomer of NpANa. UV absorption maxima for NpANa and NpALi are explained in terms of cis/trans ratios rather than in terms of ion pairing.     

A configuration interaction study of phosphine using bonded functions

A computational study is made of the effect of basis set upon the energy, properties and inversion barrier of the phosphine molecule. The calculations are performed at both the SCF and CI level. The flexibility of the double zeta basis is discussed in the light of the results.