THE FLUORESCENCE OF CAROTENOIDS

Abstract The carotenoids β-carotene, lutein, lutein epoxide and violaxanthin are fluorescent compounds. Upon excitation around 280 mμ, at wavelengths close to those of their ultraviolet absorption maxima, these carotenoids fluoresce within the range 300–400 mμ, with maximal fluorescence at approximately 320–340 mμ.     

Selektive doppelbindungsisomerisierungen an a-nor-pregnadienen

The reaction sequence 9→11→ 20→23 was carried out as model investigation for the total synthesis of 20-methyl-pregn-4-en-3-on (23) via 9 obtainable by cyclization of tetraen-ol 1. A-nor-steroid-3(5),8(14) diene 9 together with isomers 10–12 was prepared by HBr induced rearrangement of the cyclosteroids 6/7, obtained from ergosterin. 10 and 12 were isomerized on palladium charcoal to 9 or 11 respectively; 9 could be isomerized by HBr to 11. Regioselective hydrogenation of 11 yielded the mono-en 20 which was converted to 23.     

Die HOWARDsche Berechnung optimalen Anschaffungs- und Betriebsalters für Kraftwagen: Ein ergänzender Befund mit deutschen Daten

Zusammenfassung Mit Hilfe des Iterationsverfahrens vonHoward wird das optimale Anschaffungs-und Betriebsalter für ein deutsches PKW-Fabrikat bestimmt. Diese Zeiten liegen unterhalb der entsprechenden Werte, dieHoward auf Grund amerikanischer Daten erhalten hat.

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Summary By aid of theHoward-Algorithm the optimal purchase- and operating age for a German automobile is determined. These time-spans are lying below the corresponding values which were received byHoward on account of American data.

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Vorgel. v.: H.P.Künzi.     

Das Quadrupolmoment des 2,3 MeV-Zustandes in120Sn

Time differentialγγ-angular correlation measurements have been performed to determine the electric interaction of the 2.3 MeVI=5^? state of¹²⁰Sn in different polycristalline antimony compounds. A calibration of the field gradient was achieved by Mößbauerexperiments with the 23.8 keVI=3/2⁺ state in¹¹⁹Sn using identical sources. From the ratio of the measured electric interactions the ratio of the quadrupole moments is deduced as: $$\left| {\frac{{Q(2.3{\mathbf{ }}MeV level,{\mathbf{ }}I = 5^ - ,^{120} Sn)}}{{Q(2.8{\mathbf{ }}keV level,{\mathbf{ }}I = {3 \mathord{\left/ {\vphantom {3 2}} \right. \kern-\nulldelimiterspace} 2}^ + ,^{119} Sn)}}} \right| = 2.86(15)$$ . Using 0.06 (2) b for the quadrupole moment of the 23.8 keV level in¹¹⁹Sn one gets for the quadrupole moment of the 2.3 MeV level in¹²⁰Sn ¦Q(2.3 MeV level,I=5^?,¹²⁰Sn)¦=0.021 (8) b.     

Fortsetzung meromorpher Funktionen in Tori und komplex-projektiven Räumen

Ohne ZusammenfassungSatz 4.1 und 4.6 der vorliegenden Arbeit entstammen der Dissertation des Verf. (Univ. Göttingen, Mai 1967).     

Rate coefficients and final states for the dissociative recombination of LiH+

The dissociative recombination of LiH+ ions with low-energy electrons is observed at a storage ring and the final states are analyzed using fragment imaging and field ionization techniques. The rate coefficient is found to be larger than its estimated value used in astrophysical models. Mostly the highest energetically possible Rydberg states of the lithium atom are populated by the reaction, indicating a common trend for molecular recombination via the noncrossing mode.     

Study of tau decays to six pions and a neutrino

The tau decays to six-pion final states have been studied with the CLEO detector at the Cornell Electron Storage Ring. The measured branching fractions are B(tau(-)-->2pi(-)pi(+)3pi(0)nu(tau)) = (2.2+/-0.3+/-0.4)x10(-4) and B(tau(-)-->3pi(-)2pi(+)pi(0)nu(tau)) = (1.7+/-0.2+/-0.2)x10(-4). A search for substructure in these decays shows that they are saturated by intermediate states with eta or omega mesons. We present the first observation of the decay tau(-)-->2pi(-)pi(+)omega(nu)tau and the branching fraction is measured to be (1.2+/-0.2+/-0.1)x10(-4). The measured branching fractions are in good agreement with the isospin expectations but somewhat below the conserved-vector-current predictions.     

A highly congested N,N'-dioxide fluorosensor for enantioselective recognition of chiral hydrogen bond donors

A rigid C2-symmetric 1,8-diacridylnaphthalene N,N'-dioxide fluorosensor has been developed for enantioselective recognition of chiral hydrogen bond donors such as amines and amino acids.     

Enantioselective sensing of chiral carboxylic acids

A chiral 1,8-diacridylnaphthalene-derived fluorosensor has been prepared and used for enantioselective sensing of a broad variety of chiral carboxylic acids including amino acids, aliphatic acids, arylalkanoic acids, and halogenated carboxylic acids. Fluorescence titration experiments in acetonitrile gave linear Stern-Volmer plots for 1:1 and 1:2 complexes and enantioselectivities up to 4.5.