Quantum chromodynamics: Working group report

This is the report of the QCD working group at WHEPP-6. Discussions and work on heavy ion collisions, polarized scattering, and collider phenomenology are reported.     

Static and dynamic scattering behavior of regularly branched chains: A model of soft-sphere microgels

The static structure factor and the first cumulant of the time correlation function in dynamic light scattering have been calculated for a regularly branched molecule with n shells of branching generations which are connected by chains of m repeating units per chain. Ideal flexibility for the chains is assumed. The dynamic scattering functions of these soft spheres show behavior significantly different from that of a hard sphere. The theory describes very satisfactorily the static and dynamic light scattering results obtained experimentally with polyvinyl acetate microgels. The possibility of determining the glass transition temperature of latex particles is briefly discussed.     

Paraffin oil pneumonia. Analysis of saturated hydrocarbons in different human tissue

Temperature-programmed gas chromatographic analysis on columns packed with Apiezon L as stationary phase is shown to be the best method for the qualitative and quantitative analysis of simple and complex hydrocarbon mixtures when compared with all the other applicable techniques (thin-layer chromatography, column chromatography, ultraviolet spectroscopy, infrared spectroscopy, nuclear magnetic resonance spectroscopy, mass spectrometry) described in this paper. Using the method in a patient with mineral oil pneumonia it could be demonstrated that he expectorated a maximum of 79.5 mg liquid paraffin daily and also transported equally complex saturated hydrocarbons in a concentration of 1.3 mg% in plasma and of 1.6 mg% in the cellular blood components. In an additional experiment the direct determination of liquid paraffin resorbed from the gastrointestinal tract was possible in a patient with a left chyle fistula in the neck. After a dose of 50 g liquid paraffin administered as a laxative, 246 ml chyle was collected within the following 14 h which yielded a total of 4.5 mg liquid paraffin. Its composition was identical with the administered laxative. Assuming a daily lymph volume of 1.51, the resorbed amount would correspond to a resorption rate of 0.5 (see article) liquid paraffin. The importance of these results as well as the diagnostic consequences arising from the described analytical technique are discussed in detail.     

Near-infrared light-fiber spectroscopic reaction monitoring of the synthesis of diphenylurethane

The extension from the mid-infrared (MIR) to the near-infrared (NIR) region alongside the introduction of light-fiber optics has had a significant impact on vibrational spectroscopy for chemical quality- and process-control. In the present contribution the application of NIR light-fiber spectroscopy to the remote monitoring of the synthesis of diphenylurethane shall demonstrate the potential of this analytical technique. Received: 15 January 1998 / Revised: 29 May 1998 / Accepted: 2 June 1998     

How gluon bremsstrahlung inW-decays distorts the experimental signature ofe + e −→W + W −

The effect of gluon bremsstrahlung in the decays of theW-bosons on the measurement of the reactione ⁺ e ^?→W ⁺ W ^?→ hadrons is discussed. From simulation studies we find a substantial fraction of events with high jet multiplicities. At energies of \(\sqrt s = 200\) GeV this leads to probabilities of 25% or higher to misassign a jet to aW-boson when a realistic resolution of a detector is assumed. Some implications on the measurement of the decay and production properties of theW's are discussed.     

Further Characterization of UVB Radiation Effects on Langerhans Cells: Altered Expression of the Costimulatory Molecules B7-1 and B7-2

We have reported previously that low-dose UVB radiation (UVBR, 50-200 J/m²) perturbs the antigen-presenting cell (APC) function of murine Langerhans cells (LC) by interfering with yet undefined costimulatory signals. In this study, we investigated (1) the effects of UVBR on the expression of the costimulatory molecules B7-1 and B7-2 on murine LC, (2) the functional consequences of defective B7-1 and B7-2 signalling on primary and secondary T-cell responses induced by LC and (3) the mechanism by which UVBR interferes with B7-1 and B7-2 expression. Ultraviolet-B radiation dose-dependently inhibited the culture-induced upregulation of B7-1 and B7-2 on LC from both UVB-susceptible (UVB_s, C57BL/6) and UVB-resistant (UVB_R, Balb/c) mice and abrogated their capacity to stimulate proliferation of naive alloreactive T cells and of the KLH (keyhole limpet hemocyanin)-specific T helper (Th)1 clone HDK-1. The UVBR-induced suppression of B7-1 and B7-2 on LC and their perturbed APC function were related, because exogenous triggering of the B7/CD28 pathway with a stimulatory monoclonal antibody (mAb) for CD28 to UVB-irradiated LC partially restored T-cell proliferation. Such reconstitution was not observed when the mAb was added to killed LC, indicating that the UVBR-induced suppression of APC function was not due to lethal effects on LC. Conditioned supernatants from UVB-irradiated epidermal cells did not inhibit the functional upregulation of B7-1 and B7-2, suggesting that UVBR inhibits B7-1 and B7-2 upregulation by acting directly on LC and not by altering LC costimulatory function via release of soluble immunosuppressive factors. In conclusion, UVBR distorts the functional expression of B7-1 and B7-2 on LC from both UVBs and UVBR mice, thereby contributing to the failure of UVB-irradiated LC to stimulate resting alloreactive T cells or KLH-specific Thl cells.     

Zur Kenntnis der Reduktion von Metallsalzen. III. Die Reduktion von CrPO4 und CrPO4/Cr2O3-Gemischen im Wasserstoffstrom

In contrast to the reduction of FePO₄ and the Fe₂O₃ · FePO₄ phase by hydrogen, which yields the reaction products FeP and Fe₃P, respectively, it was impossible to reduce CrPO₄ and an equimolecular mixture of CrPO₄ and Cr₂O₃ to pure CrP and Cr₃P, respectively. Likewise it was impossible to produce a Cr₂O₃ · CrPO₄ phase by solid state reaction. The course of reduction of CrPO₄ described in literature must be corrected as far as always Cr₂O₃ was found in the reduction product. CrP, which was produced by direct reaction of the elements, shows extensive solid solution with FeP and FeAs.     

Near-infrared light-fiber spectroscopic reaction monitoring of the synthesis of diphenylurethane

The extension from the mid-infrared (MIR) to the near-infrared (NIR) region alongside the introduction of light-fiber optics has had a significant impact on vibrational spectroscopy for chemical quality- and process-control. In the present contribution the application of NIR light-fiber spectroscopy to the remote monitoring of the synthesis of diphenylurethane shall demonstrate the potential of this analytical technique.     

Plasma chemical preparation and characterization of perovskite-type mixed oxides

The microwave plasma enhanced chemical vapour deposition (MPECVD) was applied for the preparation of perovskite-like mixed oxides, using either the metal acetylacetonates or metal nitrates as precursors. The same materials were prepared by the citrate method as reference substances. The obtained mixed oxides were calcined at 1100 °C, tested in the methane oxidation up to 1000 °C and characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductive coupled plasma–optical emissions spectroscopy (ICP–OES) and specific surface area (BET) determination. These studies revealed that LaMnO₃ with La³⁺ cation partly substituted by Sr, Ce and Ba cations and La_0.9Sr_0.1Co_0.9Fe_0.1O₃ calcined at 1100 °C seem to be highly active and stable catalysts in methane oxidation. In the case of LaMnO₃ and La_0.9Ce_0.1MnO₃ lowest light-off temperatures were reached with the catalysts prepared by the plasma method.