Search for higher twists in meson resonance production in π− N interactions atPT≥2 GeV/c

We study the production of meson resonance atpT≥2 GeV/c inπ ⁻ Be interactions at two beam energies (150 and 300 GeV/c). The motivation is to look for the higher twist (HT) production mechanism, expected to exist besides standard hadron production through the fragmentation process of scattered quarks and gluons, the so-called leading twist (LT) mechanism. We show that the φ, K*⁰ (892) andK*⁰ (892) are found free from HT effects with a good accuracy, as expected from HT estimates and QCD sum rules. The magnitudes of thef ₂(1270) andρ ⁰ mesons signals are found larger than expected from the standard Lund (LT) Monte Carlo and from information provided bye ⁺ e ⁻ annihilation experiments. The possible connection of these excesses with HT physics is discussed. We also report the first evidence for the production off ₀(975) mesons in hadronic experiments at largep _T.     

Random poly(fluorenylene‐vinylene)s containing 3,7‐Dibenzothiophene‐5,5‐dioxide units: Synthesis,photophysical, and electroluminescence properties

The synthesis of new random poly(arylene‐vinylene)s containing the electron withdrawing 3,7‐dibenzothiophene‐5,5‐dioxide unit was achieved by the Suzuki–Heck cascade polymerization reaction. The properties of poly[9,9‐bis(2‐ethylhexyl)‐2,7‐fluorenylene‐vinylene‐co‐3,7‐dibenzothiophene‐5,5‐dioxide‐vinylene] (50/50 mol/mol, P1 ) and poly[1,4‐bis(2‐ethylhexyloxy)‐2,5‐phenylene‐vinylene‐co‐3,7‐dibenzothiophene‐5,5‐dioxide‐vinylene] (50/50 mol/mol, P2 ) were compared with those of terpolymers obtained by combining the fluorene, dibenzothiophene, and 1,4‐bis(2‐ethylexyloxy)benzene in 20/40/40 ( P3 ), 50/25/25 ( P4 ), and 80/10/10 ( P5 ) molar ratios. The polymers were characterized by ¹H NMR and IR, whereas their thermal properties were investigated by TGA and DSC. Polymers P1–5 are blue–green emitters in solution (λ_em between 481 and 521 nm) whereas a profound red shift observed in the solid state is emission (λ_em from 578 to 608 nm) that can be attributed both to the charge transfer stabilization exerted by the polar medium and to intermolecular interactions occurring in the solid state. Cyclic voltammetry permitted the evaluation of the ionization potentials and also revealed a quasi‐reversible behavior in the reduction scans for the polymers ( P1–4 ) containing the higher amounts of 3,7‐dibenzothiophene‐5,5‐dioxide units. Electroluminescent devices with both ITO/PEDOT‐PSS/ P1–5 /Ca/Al (Type I) and ITO/PEDOT‐PSS/ P1–5 /Alq₃/Ca/Al (Type II) configuration were fabricated showing a yellow to yellow–green emission. In the case of P4 , a luminance of 1835 cd/m² and an efficiency of 0.25 cd/A at 14 V were obtained for the Type II devices. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 2093–2104, 2009     

Strangeness production in p+W and S+W Interactions at 200 A GeV/c

Strange and multistrange baryon and antibaryon production is a useful probe into the dynamics of the hot hadronic matter created in central heavy ion interactions. Relative production yields and transverse mass spectra are presented and compared for pW and SW interactions.     

Die Bestimmung von Methoxyl- und Äthoxylgruppen nebeneinander

Zusammenfassung Die Analyse von Methoxyl- und Äthoxylverbindungen durch Kombination des Chromsäureoxydationsverfahrens von Kuhn und L'Orsa mit dem Zeiselschen Verfahren ermöglicht die Bestimmung beider funktioneller Gruppen nebeneinander. Bei Abwesenheit anderer C-Methylgruppen sind die Ergebnisse für beide Gruppen sehr genau.

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Determination of methoxyl and ethoxyl groups side by side

Summary Analysis of methoxyl and ethoxyl compounds by combination of the chromic acid oxidation method of Kuhn and L'Orsa with the Zeisel method enables determination of both functional groups side by side. In the absence of other methyl groups the results for the two groups are very precise.

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Herrn Univ.-Prof. Dr. Hans Lieb zum 90. Geburtstag gewidmet.     

Visible continuum generation using a femtosecond erbium-doped fiber laser and a silica nonlinear fiber

Supercontinuum extending to visible wavelengths is generated in a hybrid silica nonlinear fiber pumped at 1560 nm by a femtosecond, erbium-doped fiber laser. The hybrid nonlinear fiber consists of a short length of highly nonlinear, germano-silicate fiber (HNLF) spliced to a length of photonic crystal fiber (PCF). A 2 cm length of HNLF provides an initial stage of continuum generation due to higher-order soliton compression and dispersive wave generation before launching into the PCF. The visible radiation is generated in the fundamental mode of the PCF.     

Probing optical microfiber nonuniformities at nanoscale

We demonstrate a novel, simple, and comprehensive method for probing optical microfiber surface and bulk distortions with subnanometer accuracy. The method employs a regular optical fiber as a probe that slides along a microfiber transmitting the fundamental mode. The fraction of radiation power absorbed in the probe depends on the local distribution of the mode propagating in the microfiber. From the measured variation of the absorbed power, we determine the variation of the effective microfiber radius, which takes into account both the microfiber radius and refractive index variations. Furthermore, we verify the cylindrical symmetry of the microfiber nonuniformities by probing the microfiber from different sides. These results explain observed transmission losses in silica microfibers and open broad opportunities for microfiber investigation.     

Spectral polarimetry with a differential group delay bias

We show that the addition of a polarization controller and bias differential group delay to a spectral polarimeter increases the amount of polarization information that can be extracted from a Stokes spectrum measurement. We use this biased spectral polarimetry on 40-Gbit/s signals to measure the polarization mode dispersion of the optical fiber through which they propagate. Our measurements do not require any control of the polarization at the fiber input. Averaging measurements from several settings of the polarization controller yields improved accuracy, and, after data rejection is applied, both the accuracy and the number of valid data points is increased when using several measurements.     

Determination of superoxide dismutase in erythrocytes by a chemiluminescent assay

A highly rapid chemiluminescent assay for the determination of superoxide dismutase (SOD) activity in erythrocytes was developed. The inhibition of the luminescent emission caused by the decrease of generated superoxide anions was measured. The aim of this work was to verify the application of a non amplified luminol SOD luminescent assay (CLM) in erythrocytes starting from an amplified method already used for the determination of XOD activity in milk (CLME). Both the assays had a detection limit of 3x10(-2)+/-7x10(-3) U/ml of SOD at 2sigma level, and a linear range of activity from 5.2 to 0.03 U/ml of SOD. The imprecision of assays (repeatability) presented coefficients of variations ranging from 3.1 to 7.9% for the CLME method and from 0.6 to 17.7% for CLM method. Both luminescent techniques were compared using a spectrophotometric kit, that had a detection limit of 0.3 U/ml, and showed good agreement.     

Verkürzung der Analysenzeit bei der Mikrobestimmung von Kohlenstoff und Wasserstoff

Zusammenfassung Eine Methodik zur gravimetrischen Schnellbestimmung von Kohlenstoff und Wasserstoff wird beschrieben.Es werden gleichzeitig die Katalysatoren vonKörbl undVeea angewandt. Die Gesamtanalyse dauert etwa 16 bis 17 Minuten.

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Summary A procedure is described for the rapid gravimetric determination of carbon and hydrogen. TheKörbl andVeea catalysts are employed concurrently. The entire analysis requires about 16–17 minutes.

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Herrn Univ.-Prof. Dr.Hans Lieb zum 80. Geburtstag gewidmet.

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Herrn Prof.L. Musajo sind wir für wertvolle Hinweise und Korrektur zu aufrichtigem Dank verpflichtet.