Powering the analytical glow discharge

The glow discharge may be powered by direct current (dc), radio frequency (rf) and pulsed discharge sources. Each has specific advantages and special features that should be considered by analysts using the various forms of glow discharge spectroscopy. This paper reviews some of the factors that contribute to the selection of a power source for the glow discharge.     

Evaluation of an Economical Sunlamp that Emits a Near Solar UV Power Spectrum for Conducting Photoimmunological and Sunscreen Immune Protection Studies

Expense and inconvenience have restricted the use of the filtered xenon are lamp (solar simulator) as a UV source for conducting large-scale animal studies. Because sunscreen immunoprotective levels are significantly affected by the UV power spectrum of the source it is imperative that a solar simulating source be used for accurate measurements of sunscreen protection levels that are relevant to human UV exposures from sunlight. However, relatively inexpensive sunlamps, e. g. the UVA-340, that emit a UV power spectrum similar to that of a solar simulator are available. Unlike FS-type UVB sunlamps, which have a significant amount of effective immunosuppressive nonsolar UV energy at wavelengths below 295 nm, the immunosuppression effectiveness spectrum of UVA-340 sunlamps was nearly identical to that of a solar simulator. The purpose of this study was to evaluate this sunlamp for conducting photoimmunological and sunscreen immune protection studies. Groups of C3H mice were exposed to a range of UVA-340 sunlamp doses (0.25 KJ/m² to 20.0 KJ/m²) to establish a dose-response curve and determine the minimum immune suppression dose (MISD) for induction of local-type suppression of contact hypersensitivity (CH). The MISD, defined as the lowest UV dose given to produce ～50% suppression of the CH response in mice, was determined to be 1.0 kJ/m² for UVA-340 sunlamps. Immune protection tests on four marketed sunscreen lotions (sun protection factors [SPF] 4, 8, 15 and 30) were then conducted with UVA-340 sunlamps using MISD as the endpoint. The immune protection factors for these sunscreens were equivalent to the level of protection predicated by their labeled SPF. These results are similar to those we have previously obtained using a solar simulator. We conclude from these data that the immunosuppressive effects of UVA-340 sunlamps are similar to those of a solar simulator; however, further studies are needed to determine if UVA-340, or similar, sunlamps are a viable alternative to the solar simulator for conducting large-scale animal experiments that require a relevant UV solar spectrum.     

Radiation degradation of copolymers of methyl methacrylate and 3-oximino-2-butanone methacrylate

Copolymers of methyl methacrylate and 3-oximino-2-butanone methacrylate (OM) were investigated as deep-UV and e-beam resists. Their increased sensitivity relative to PMMA (up to 50 times) was correlated with the radiation chemical yields of the volatile products and main chain scissions. The degradation of these copolymers, activated by the 3-oximino-2-butanone entity, is discussed in terms of energy absorption mechanisms and the subsequent scission reactions.     

Beiträge zur quantitativen Dünnschichtchromatographie. V

Zusammenfassung Eine dünnschichtchromatographische Trennung des Wismuts von einem Überschuß an Metallen der Schwefelwasserstoffgruppe wurde beschrieben. Als Laufmittel dient ein Gemisch von tert.-Butanol, Salzsäure und Wasser. Nach Absaugen der Sorptionsschicht wird das Wismut mit MDCM spektralphotometrisch bestimmt. Standardabweichung und Varianz des Verfahrens werden angegeben.

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Summary A thin layer Chromatographic separation of the bismuth from an excess of metal ions of the hydrogen sulfide group is described. A mixture of tert. butanol, hydrochloric acid and water serves as mobile phase. After sucking off the sorption layer, the bismuth is determined spectrophotometrically with MDCM. The standard deviation and the variance of the procedure is given.

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Résumé On décrit une séparation par Chromatographie en couche mince du bismuth de métaux en excès du groupe de l'hydrogène sulfuré. On utilise comme éluant un mélange de butanol tert., d'acide chlorhydrique et d'eau. Après aspiration de la couche de sorption, on dose par spectrophotométrie le bismuth par le MDCM. On communique l'écart-type et le coefficient de variation du procédé.

     

Darstellung und thermische Zersetzung von Lithiumcyanuraten Eine einfache Methode zur Gewinnung von wasserfreiem Lithiumcyanat

Zusammenfassung Die Darstellung von Mono-, Di- und Tri-Lithiumcyanurat durch Umsetzung von Cyanursäure mit LiOH bzw. Li₂CO₃ in hochsiedenden Alkoholen und durch lösungsmittelfreie Festkörperreaktion wird beschrieben. Die Festkörperreaktionen werden mit Hilfe thermoanalytischer Methoden untersucht. Die Reaktion mit LiOH erfolgt in zwei Schritten und ergibt bei 400°C. Trilithium-cyanurat. Unter denselben Bedingungen wird mit Li₂CO₃ nur Dilithium-cyanurat gebildet. Die Thermolyse von Trilithium-cyanurat bei 550°C liefert in hoher Ausbeute Lithiumcyanat und stellt somit eine einfache Methode zur Darstellung dieser Verbindung in wasserfreier Form dar.

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Formation and thermolysis of lithium cyanurates (a simple preparation of anhydrous lithium cyanate)

The formation of mono-, di- and tri-lithium cyanurate by reaction of LiOH or Li₂CO₃ with cyanuric acid has been investigated as a solid state reaction and by using high boiling alcohols as reaction medium. For investigating the solid state reactions thermoanalytical methods were used. The reaction with LiOH proceeds in two steps yielding trilithium cyanurate at 400°C. Under the same conditions only dilithium cyanurate is formed by reaction with Li₂CO₃. Lithium cyanate is obtained in high yields by thermolysis of trilithium cyanurate at 550°C. This procedure is therefore a simple method in synthesizing pure anhydrous lithium cyanate.

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Mit 3 Abbildungen

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Herrn Univ.-Prof. Dr.O. Kratky zum 70. Geburtstag gewidmet.     

Random peptide synthesis using immobilized enzymes in high concentrations of organic solvents

Trypsin, leucine aminopeptidase, and carboxypeptidase B were separately immobilized on controlled pore glass and reacted with a dipeptide substrate in high concentrations of either acetone or 1-propanol. Hydrolytic activity was demonstrated and evidence for the possible synthesis of peptide polymer is presented. Directed synthesis using amino acids and blocked amino acids as substrates was not successful.     

On [Na(POCl3)4]+ Complex Ion Formation: Conductivity,Raman, and NMR studies in the system phosphoryl chloride–sodium tetrachloro aluminate and related compounds

The system POCl₃–NaAlCl₄ was investigated by measuring the conductivity and the Raman and NMR spectra (²⁷Al, ²³Na and ³¹P) as a function of the mol fraction x of NaAlCl₄ in POCl₃. Additionally, Raman spectra of POCl₃ solutions of NaFeCl₄, LiAlCl₄, LiFeCl₄, and KAlCl₄ were recorded. In solutions containing Li⁺ or Na⁺ ions a liquid to solid (or jelly) phase transition was observed under certain conditions, dependent on salt concentration and temperature. Observed changes in the Raman spectra of the electrolyte solutions in comparison to the pure solvent POCl₃ demonstrate the existence of interactions. Clearly, the POCl₃ eigenfrequencies and hence the molecules are pertubed. The formation of [M(POCl₃)₄]⁺ complexes (M = Li, Na) can be deduced from the Raman measurements. NMR investigations support this conclusion. For assigning of Raman spectra, (Li⁺, K⁺) cation and ([FeCl₄]^?, [SbCl₆]^?) anion substitutions were employed.     

Studies on thermal decomposition of 3-chlorobenzoates of rare earth elements in air atmosphere

The conditions of thermal decomposition of the 3-chlorobenzoates of Y, La and the lanthanides from Ce(III) to Lu have been studied. The complexes of La, Pr(III), Sm, Eu, Gd, Tb(III) and Dy were prepared as heptahydrates, those of Ce(III) and Y as pentahydrates, that of Nd as the tetrahydrate, that of Ho as the dihydrate and those of Er, Tm, Yb and Lu as anhydrous salts. On heating, these complexes decompose in three or two stages. They first lose some water molecules and then decompose to oxides through the intermediate formation of LnOCl. Cerium(III) 3-chlorobenzoate loses its crystallization water in two stages and yields the anhydrous salt, which is then transformed directly into CeO₂. All these complexes melt before decomposition in the temperature range 441–513 K.