A comparison of inductively coupled argon plasma atomic emission spectrometry and electrothermal atomization atomic absorption spectrometry in the determination of copper and zinc in serum

Summary A comparison of performance characteristics of ICAP-AES and ETA-AAS experienced in analyzing Cu and Zn in blood serum is described. Accuracy and precision were evaluated by a statistical procedure permitting graphical representation of the results. It was concluded that ETA-AAS is very suitable for monitoring and screening purposes in toxicology and clinical chemistry whereas ICAP-AES is to be preferred when more precise determinations are required.

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Vergleich von AES mit induktiv gekuppeltem Argonplasma und AAS mit elektrothermischer Atomisierung für den Fall der Kupfer- und Zinkbestimmung im Serum

Zusammenfassung Die Leistungsfähigkeit der beiden Methoden wurde verglichen, wobei Richtigkeit und Reproduzierbarkeit statistisch mit graphischer Darstellung der Ergebnisse ausgewertet wurden. Als Schlußfolgerung ergab sich, daß sich die ETA-AAS als Überwachungs- und Screeningverfahren in der Toxikologie und klinischen Chemie eignet, während für höhere Präzision die ICAP-AES vorzuziehen ist.

     

The smallest resonance energy transfer acceptor for tryptophan

The utility of diazirine ligands as acceptors in resonance energy transfer (RET) distance measurements with tryptophan or tryptophan analogues as donor is reported. The principle is demonstrated for a diazirine derivative of d-mannitol, 2-azi-2-deoxy-d-arabino-hexitol, and single-tryptophan-containing mutants of the mannitol transporter, EIImtl, from E. coli. The F?rster distance is 10 A for the tryptophan-diazirine donor-acceptor couple, allowing the measurement of distances up to 17 A. The versatility of tryptophan as an intrinsic spectroscopic probe in protein chemistry and the small size of the diazirine group makes this a very attractive donor-acceptor couple for accurate RET distance information in protein chemistry.     

Quantum mechanical criteria for choosing appropriate voltage stabilization additives for polyethylene

One of the major application fields for solid dielectric polymers is their use as insulating materials for power cables. Since the electrical aging of the insulating polymeric materials is one of the most important factors affecting the service lifetime of power cables, developing a model which can be used to design materials with an improved resistance to electrical degradation would be highly beneficial. We developed a model for the electrical field within the polymer material contaminated with a sharp conducting defect (a metallic needle) and defined a parameter characterizing the resistance of polymer to electrical treeing. The model was used to analyse data for the electrical degradation of polyethylene stabilized with polycyclic aromatic hydrocarbons. Based on quantum mechanically calculated electron affinities and ionisation potentials of the stabilizer molecules, we discovered that if a molecule is to be considered for voltage stabilization use it has to have a specific combination of the ionisation potential and adiabatic electron affinity. The model allows for a choice of appropriate voltage stabilizers based on theoretical calculations only and can help to facilitate any experimental study for choosing appropriate voltage stabilizer additives.     

Untersuchung von Eiern und Eiwaren

Ohne Zusammenfassung     

INTERACTION OF PHOTODYNAMICALLY INDUCED CELL KILLING and DARK CYTOTOXICITY OF RHODAMINE 123

Abstract— Loss of clonogenicity of Chinese hamster ovary (CHO) cells, murine L929 fibroblasts and human bladder carcinoma T24 cells caused by photodynamic treatment (PDT) with hematoporphyrin derivative (HPD) is synergistically enhanced by subsequent incubation with rhodamine 123 in the dark. For CHO and L929 cells this synergistic interaction can be explained by an increased uptake of rhodamine 123 as the result of the photodynamic treatment. With aluminum phthalocyanine (AIPc) as photosensitizer only additive effects were observed in the three cell lines. Incubation in the dark with rhodamine 123, followed by a photodynamic treatment with HPD, resulted in an antagonistic interaction with regard to loss of colony formation. With AIPc the combination of treatments resulted in an additive effect with L929 and T24 cells, whereas with CHO cells a slight antagonistic interaction was observed. An antagonistic effect was also observed in model experiments, treating histidine photodynamically with HPD and measuring oxygen consumption. A possible explanation of these results could be an interaction or complex formation of rhodamine 123 with HPD resulting in a diminished singlet oxygen production. With AIPc this does not take place.     

A non-selfdual automorphic representation of GL3 and a Galois representation

Oblatum 13-XI-1992 & 22-X-1993