Corpuscular diagnostics of a hollow-cathode discharge-III. The metal-ions-regime evolution

The variations in time of mass spectra of ions, extracted from the hollow-cathode discharge in the regime of the intensive sputtering of the cathode material were measured. The mass spectrum changes in time conspicuously. From the results of measurements a distinct anisotropy of ion beam is inferred. The discharge turns into a metal-ions regime.The helpful discussions with Dr. J. Musil are gratefully acknowledged.     

The small momentum transfer k L o C→K S 0 C regeneration at high energies

Results of the first elastic K _S ^o regeneration experiment on carbon, using magnetic spark chamber spectrometer, are presented in the beam momentum interval 10p50 GeV/c. The d ifferentia cross section d/dt is reconstructed in the range 0·0025–t0·02 (GeV/c)² and its slopeB is found to be momentum independent with an average valueB=(65±11) (GeV/c)^–2. The results are in agreement with the calculations using the coherent production model.     

Triplet losses in dye lasers

The expression for losses due to triplet states in dye laser considered as a six-level system is given. It is shown that triplet losses depend on pumping parameters and photon number. Depending on molecular and cavity parameters two different behaviours of dye lasers are expected. Physical conditions are discussed in which triplet losses as well as photon number undergo a jump at the threshold.     

Bestimmung von C-Methylgruppen in organischen Sauerstoffverbindungen durch Oxydation mit Chromsäure unter optimalen Bedingungen. I

Zusammenfassung Eine Reihe sauerstoffhaltiger Modellsubstanzen, die Methylgruppen am primären, sekundären oder doppelt gebundenen Kohlenstoffatom enthalten, wurden mit einem Gemisch von 2 T. 5-n Chromsäure und 1 T. konz. Schwefelsäure 45 Minuten bei 130° C oxydiert. Die entstandene Essigsäure wurde mit Wasserdampf abdestilliert und alkalimetrisch titriert. Die angeführten Reaktionsbedingungen können als optimal angesehen werden, da sie die größte oxydative Wirkung haben, bei der jedoch Essigsäure nicht weiter oxydiert wird. Der Abbau des Kohlenstoffskeletts verläuft schneller und vollständiger als bei der Methode vonKuhn undRoth. Die Essigsäureausbeute lag zwischen 0,70 und 0,95 Mol Essigsäure je C-Methylgruppe und wurde in Abhängigkeit von der Struktur der untersuchten Stoffe diskutiert.

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Determination of C-methyl groups in organic oxygen compounds through oxidation with chromic acid under optimal conditions

Summary A number of oxygen-containing model substances, which contained methyl groups on primary, secondary or doubly bound carbon atoms, were oxidized with a mixture of 2 parts of 5N chromic acid and 1 part of conc. sulfuric acid for 45 minutes ar 130° C. The resulting acetic acid was distilled off with steam and titrated alkametrically. The cited reaction conditions may be regarded as optimal, because they exert the greatest oxidative action, which however the acetic acid is not further oxidized. The degradation of the carbon skeleton proceeds faster and more completely than in the method ofKuhn andRoth. The yield of acetic acid lay between 0.70 and 0.95 mol acetic acid per C-methyl group and was discussed with respect to the structure of the investigated material.

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In dieser Mitteilung ist der erste Teil der Dissertationsarbeit von Frau Dipl.-Ing.B. Voláková inbegriffen.     

Extraction of Am(III) in the presence of lanthanides and yttrium by benzyldimethyldodecylammonium nitrate from acidic nitrate solutions

We have investigated the effect of coextraction of lanthanides and yttrium on the distribution coefficients D_Am in the extraction of americium by benzyldimethyldodecylammonium nitrate (BDMLNNO₃) from nitrate solutions. In the coextraction of lanthanides, the extraction of Am(NO₃)₃ is suppressed, which is markedly manifested in the extraction of light lanthanides (La, Ce, Pr); of the series of lanthanides their extraction is the highest. The effect of nitric acid and the possibility of separation of lanthanides and americium by the application of three-stage multiple extraction is discussed.     

Effects of annulation on the mass spectral behaviour of monosubstituted bicyclo[4.3.0]-3-nonenes and bicyclo[4.3.0]-3,7-nonadienes

The mass spectra of the title compounds differ considerably depending on the annulation of the bicyclic skeleton. For a series of alkyl derivatives the cis-annulated compounds show a higher abundance of the products due to the retro Diels-Alder cleavage than the corresponding trans isomers. The cis-annulated esters and alcohols lose a molecule of ethanol and water, respectively, more easily than the corresponding trans isomers. Effects of conformation and configuration are discussed.     

Radical polymerization of n-substituted methacrylamides

The relationship between the structure of monomer and kinetics of the radical polymerization of N-ethylmethacrylamide, N-butylmethacrylamide and N-phenylmethacrylamide in methanol and in dimethylsulphoxide was investigated. The reaction order with respect to initiator is 0·5 in all cases; the order with respect to monomer is independent of the type of substituent but depends on the solvent and on the viscosity of the reaction mixture. The polymerization rate, the value of $\text{κ}{}_{\mathrm{p}}\text{/κ}{}_{\mathrm{t}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, and the initiator efficiency decrease in the series N-phenylmethacrylamide, N-ethylmethacrylamide and N-butylmethacrylamide. The overall activation energy of polymerization for the monomers lies between 16 and 20 kcal/mol.     

Infrared study of adsorption of methanol,deuterated methanol and ethylene on the surface of ZSM-5 type zeolite

The surface species resulting in exposing of the ZSM-5 zeolite at elevated temperatures to methanol, deuterated methanol or ethylene have been studied by IR method.The three-step adsorption at 150°, 300°, 420° C or one-step adsorption at 420° C have been carried out in order to prepare the samples for IR. In all cases the most prominent band appeared in the range 1495–1515 cm^?1; besides two bands at about 1470 and 1370 cm^?1 have been observed. On the basis of Greenler's results and of the shift values of the bands in our spectrum of adsorbed deuterated methanol it was supposed that the band 1495–1515 cm^?1 is due to the OCO group from the surface species. Moreover these species would involve both oxygen atoms from the surface of zeolite but not from OH groups of methanol.     

P, p, T Surfaces of real gases and the Riemann-Hugoniot catastrophe

Analysing experimentally determined P, ?, T data of N₂, ethylene, propene, CO₂ and Xe by a new mathematical technique, we present evidence that their isothermal pressure-density dependence exhibits behaviour characteristic of a Riemann-Hugoniot catastrophe, in analogy to a van der Waals gas for above and sub critical isotherms.     

Amperometry with two polarizable electrodes. XVI

Summary Conditions for the magnesium determination in alkaline solution by EDTA titration with biamperometric indication were examined. The most preferable pH range was found to be above 9.6. A reliable determination can be carried out in the presence of Ca, Ni, Cu and Co up to the ratio of 11. In the case of higher concentrations of Cu and Ni masking with potassium cyanide can be used. In this case, however, a change of the titration curves occurs.A new method for the determination of water-hardness by biamperometric indication is proposed. It is rapid and accurate and meets the requirements of routine and research work (error: ±1%).

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Zusammenfassung Die Bedingungen für die Magnesiumbestimmung in alkalischer Lösung durch Titration mit ÄDTA bei biamperometrischer Endpunktsanzeige wurden untersucht. Der günstigste pH-Bereich liegt über 9,6. Zuverlässige Bestimmungen können in Gegenwart von Ca, Ni, Cu und Co bis zum Verhältnis 11 ausgeführt werden. Höhere Konzentrationen an Cu oder Ni können mit KCN maskiert werden, wobei allerdings eine Umkehrung der Kurven auftritt.Ein Verfahren zur Wasserhärtebestimmung mit biamperometrischer Indikation wird vorgeschlagen, das schnell durchzuführen ist und genaue Werte liefert (Fehler ±1%).

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Part XV: Vorlíek, J., and P. Peták: Microchem. J. 12, 466–471 (1967).