Resonance enhanced three-photon absorption of molecular iodine

D ← X resonance enhanced three-photon excitation spectrum of iodine was observed by a cw intracavity absorption technique. Vibrational quantum numbers of D ← X transitions are given for every major spectral feature. The corresponding one-photon enhancement from the B state is evident from the one-photon vibrational assignment. The spectroscopic constants for the D state are v₀₀ = 40 998 cm^?1 ω′₀ = 113 cm^?1 and ω′₀χ′₀ = 0.045 cm^?.     

Anwendung mikroanalytischer Methoden zur Lösung kunst- und kulturgeschichtlicher Probleme

Zusammenfassung Mit bekannten mikroanalytischen Arbeitsmethoden — Oberflächenreaktionen, Abstrichuntersuchungen mit dem Korundstäbchen, Schutzschichtreaktionen sowie dem Abdruckverfahren — lassen sich archaeometrische Probleme einer Lösung näherbringen. Die Art der Korrosion kupferhaltiger Oberflächen wurde diskutiert.

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Application of microanalytical methods to the solution of artistic- and cultural historical problems

Summary Archeometrical problems are brought closer to a solution by means of known microanalytical procedures-surface reactions, surface scraping studies with the corundum rod, protective layer reactions as well as the imprint method. A discussion of the corrosion of copper-bearing surfaces is included.

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Vortrag anläßlich der Tagung Chemische Analysen — Kunst- und Kulturwissenschaften im Reiß-Museum in Mannheim, 19.–21. September 1974.     

A new technique for the identification of chloride ions by the formation of chromyl chloride

Summary A new technique is described for the identification of the chloride ion through the formation of chromyl chloride, based on the extraction of the latter with carbon tetrachloride. The identification limit is 2g of chloride. It is possible to carry out the test in the presence of many other anions, including fluoride, which cannot be present when the traditional distillation technique is employed.

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Zusammenfassung Vorgeschlagen wird eine neue Technik zum Chloridnachweis durch Bildung von Chromylchlorid. Dieser Nachweis beruht auf der Extraktion des Chromylchlorids mit Tetrachlorkohlenstoff. Die Nachweisgrenze liegt bei 2g Chlorid, wobei die Möglichkeit besteht, den Test auch in Gegenwart von Fluorid durchzuführen, das bei Anwendung der üblichen Destillationsmethoden nicht anwesend sein darf.

     

Darstellung und Reaktionen des 3-Ethinyl-2,4-diformyl-pentandials

Preparation and physical and chemical properties of 3-ethinyl-2,4-diformyl-pentandial (3 a) and its salts are described.3 a contains 2 malonaldehyde groups. Starting from3 a, 4H-pyranes, 4H-dihydropyridines, dipyrazoles, diisoxazoles, bisdiazepines and vinamidine derivates are obtained.

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Mit 1 Abbildung     

Zur Umsetzung des 3,4,5,6-Tetrahydro-6-hydroxy-4,4,6-trimethyl-1,3-thiazin-2-thions mit sekundären Aminen

Tetrahydro-6-hydroxy-trimethyl-1,3-thiazine-2-thione (1) reacts with secondary amines via the dialkylammonium-3-oxoalkyldithiocarbamate3, either via isothiocyanates6 to 4-dialkylaminodihydro-2(1H)-pyridinethiones7 or to dialkylammonium dithiocarbamates (13), depending on the amine used and the reaction conditions. Subsequently, 6-dialkylaminotetrahydro-1,3-thiazine-2-thiones11 or tetrahydro-6-mercapto-1,3-thiazine-2-thione10 are formed. On being heated to reflux,11 reacts to pyridinethione7 and 4-dialkylaminodihydrothiopyranthione19. With secondary amines only13 is formed from tetrahydro-6-hydroxytetramethyl-1,3-thiazine-2-thione20. The reaction of dihydrotrimethyl-1,3-thiazine-2-thione21 with secondary amines leads to N,N-dialkylthioureas16 or dialkylammonium thiocyanates17 and with dialkylformamides 4-dialkylaminodihydropyridinethiones7 are formed. Dihydrotetramethyl-1,3-thiazine-2-thione24 reacts neither with secondary amines nor with dialkylformamides.     

Beiträge zur Chemie der Pyrrolpigmente, 19. Mitt.: Die elektrochemische Oxidation von Pyrromethenonen und Pyrromethenen (Gallenpigment-Partialstrukturen)

The electrochemical oxidation of arylmethylene-pyrrolinones, pyrromethenones and pyrromethenes as representative bile pigment partial structure models was investigated by means of a rotating disc platinum electrode using acetonitrile as the solvent. Two different oxidation reactions were found. The first reaction being a reversible one-electron oxidation with compounds of the arylmethylene-pyrrolinone series and pyrromethenones which are unsubstituted in position 5 of the pyrrole ring. A two step reaction (the first one reversible, the second irreversible) on the other hand was found to be typical for pyrromethenones bearing a methyl group in this position.Through protonation the first step is at a higher potential, whereas the second one is lowered and becomes reversible. The resulting oxidation pattern can be interpreted analogous to the oxidation of hydroquinones in aprotic solvents.The geometrical isomers of a pyrromethenone were oxidized at appr. the same potential, but there is a strong dependence of the potential of the first oxidation step on the substitution: a higher degree of alkylation favours oxidation by lowering the oxidation potential.

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Mass spectrometry analysis of synthetically myristoylated peptides

Myristoylpeptides were synthesized in order to determine if a neutral loss of 210 Da, C14H26O (the mass of the myristoyl moiety), was universal and observable by both liquid chromatography electrospray ionization quadrupole ion trap (LC-ESI-QIT) and matrix-assisted laser desorption/ionization time-of-flight time-of-flight (MALDI-ToF/ToF) mass spectrometry. Myristoylation was successfully introduced on the N-terminus, internally on the amino group of lysine and arginine. Larger peptides and the arginine compounds needed elevated temperatures for myristoylation. To our knowledge, this is the first report of a chemically-synthesized myristoylated arginine in a peptide. Collision energy studies for the LC-ESI-QIT instrument showed that modified peptides and a loss of 210 Da could be detected under commonly used conditions (energy level between 30 and 42%) with picomole amounts of sample. The loss of myristoyl moiety is observed on the MALDI-Tof/Tof mass spectrometer as well. Due to the hydrophobic properties of the myristoyl moiety, it is not surprising that the modified peptides all formed at least dimers, and in some cases trimers. We were also able to distinguish a mixture of two mono-myristoylated peptides. MS3 data from the LC-ESI-QIT instrument on a di-myristoylated peptide indicates the loss of 210 Da at either the N-terminus or lysine. We were also able to analyze a mixture of modified and unmodified peptides on the MALDI-ToF/ToF instrument. The data presented in this paper demonstrates the constant neutral loss of the 210 Da, C14H26O, from both N-terminally and internally myristoylated peptides can be identified unambiguously using LC-ESI-QIT or MALDI-ToF/ToF mass spectrometers. This will be a useful tool in determining the myristoylation status of candidate proteins after enzyme digestion, and in elucidating the modification sites of internal myristoyl proteins.     

Simultaneous determination of cefazolin in rat blood and brain by microdialysis and microbore liquid chromatography

A sensitive microbore liquid chromatographic method combined with the minimally invasive technique of microdialysis was devised for simultaneously and continuously monitoring the levels of unbound blood and brain cefazolin in rats. Microdialysis probes were inserted into the jugular vein and brain striatum for blood and brain sampling, respectively. Chromatographic conditions consisted of a mobile phase of methanol-acetonitrile-100 mM monosodium phosphoric acid (20:10:70, v/v, pH 4.5) pumped through a microbore reversed-phase column at a flow rate of 0.05 mL/min. The ultraviolet detection wavelength was set at 270 nm. An on-line design allowed direct and continuous analysis of protein-free samples in the dialysate. Microdialysis probes, being home-made, were screened for acceptable in vivo recovery. Chromatographic resolution and detection were validated for response linearity as well as intra-day and inter-day variabilities. This method was then applied to pharmacokinetic profiling of protein unbound cefazolin in both the blood and brain following intravenous administration (10 mg/kg, i.v., n = 6). Rapid appearance of cefazolin in the rat brain striatal dialysate following drug injection suggested good blood-brain barrier penetration. According to a non-compartmental pharmacokinetics model, the area under the concentration (AUC) vs time ratio of cefazolin in rat brain and blood was 6%.     

A novel route for waste water treatment: photo-assisted Fenton degradation of dye pollutants accumulated in natural polyelectrolyte microshells

The efficient accumulation of dyes in constructed natural polyelectrolyte microshells under moderate conditions, combined with the photo-assisted Fenton reagent, opens a new route for the effective elimination of dye pollutants from waste water.