Suppression of high-p{T} neutral pion production in central Pb+Pb collisions at sqrt[S{NN}]=17.3 GeV relative to p+C and p+Pb collisions.

Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at sqrt[S{NN}]=17.4 GeV at midrapidity (2.3 less than or approximately equal eta{lab} less than or approximately equal 3.0) over the range 0.7 less than or approximately equal p{T} less than or approximately equal 3.5 GeV/c. The spectra are compared to pi{0} spectra measured in Pb+Pb collisions at sqrt[S{NN}]=17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N{part} less than or approximately equal 300), the yield of pi{0}'s with p{T} greater than or approximately equal 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N{coll}), while for central Pb+Pb collisions with N{part}greater than or approximately equal 350, the pi{0} yield is suppressed.

Interferometry of direct photons in central 208Pb + 208Pb collisions at 158A GeV.

Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158A GeV. The invariant interferometric radii were extracted for 100

Encapsulation of aluminium hydroxide fillers with poly-methyl-methacrylate.

A process was developed for the microencapsulation of inorganic filler particles with poly-methyl-methacrylate, to increase the interaction between the hydrophilic filler particles and a polymer matrix. The filler utilised was aluminium hydroxide with an average diameter of 1.9 microm and a specific surface area of 5 m2/g. The process comprised a surface modification, in which a monolayer of isopropoxy titanium isostearate was chemically bound to the surface to render it hydrophobic and to ensure a chemical bond between the filler and the organic phase. Then, an encapsulation reaction was carried out by means of an emulsion-like polymerization process at monomer starved conditions. The modified particles were stabilized in water with sodium-dodecyl-sulphate. A redox system consisting of cumene-hydroperoxide in combination with sodium-formaldehyde-sulphoxylate and iron(II) salt was applied for the initiation of the polymerization. Besides surface polymer, free polymer particles were also formed. The parameters which varied were the filler concentration, the concentration of the initiator components and the surfactant concentration. At optimum conditions, approximately 50% of the added monomer polymerized at the modified filler surface, thus forming encapsulated filler particles. SEM together with TGA analysis indicated that a smooth polymer layer had been formed on the filler surface. At high filler loading, however, coagulation occurred.

Morphological and neurochemical differentiation of large granular layer interneurons in the adult rat cerebellum.

The granular layer of the cerebellar cortex consists of densely packed neuronal cells, classified into granule cells and large interneurons. In this study, we provide a comparative survey of large granular layer interneurons in the adult rat cerebellum based on both morphological and neurochemical criteria. To this end, double immunofluorescence histochemistry was performed by combining antibodies against the cytoplasmic antigen Rat-303, calretinin, the metabotropic glutamate receptor mGluR2 and somatostatin. Based on Rat-303/calretinin double immunohistochemistry, three distinct populations of large granular layer interneurons could be discerned: cells immunopositive for Rat-303, calretinin or both. Rat-303 or calretinin single-labeled cells represented Golgi cells and unipolar brush cells, respectively. Rat-303/calretinin double-labeled cells located just underneath the Purkinje cell layer represented Lugaro cells. Morphometrical analysis distinguished two populations of Rat-303-positive Golgi cells according to their location: vermis versus hemisphere. Immunostaining for the metabotropic glutamate receptor mGluR2 combined with Rat-303 or calretinin revealed that the majority of Golgi cells (about 90%) appeared to be mGluR2 positive. Lugaro cells were mGluR2 negative. In addition, a limited population of large polymorphous interneurons in the depth of the granular layer with morphological features resembling Golgi cells also displayed Rat-303/calretinin immunoreactivity and were mGluR2 negative. Double immunohistochemistry for Rat-303 and somatostatin revealed three populations of labeled cells in the depth of the granular layer. Besides double-labeled Golgi cells, Rat-303 or somatostatin single-labeled cells were present. Based on mGluR2/somatostatin and calretinin/somatostatin double immunostainings, Rat-303 single-labeled cells were found to correspond to Rat-303/calretinin-positive, mGluR2-negative Golgi-like cells, while the identity of somatostatin single-labeled cells remained unclear. The data presented in this article elaborate previous reports on the morphological and neurochemical differentiation of large interneurons in the rat cerebellar granular layer. In addition, they indicate that the current classification of these cells into Golgi cells, Lugaro cells and unipolar brush cells does not describe the observed neurochemical heterogeneity.

Three-pion interferometry results from central Pb+Pb collisions at 158A GeV/c.

Three-particle correlations have been measured for identified pi(-) from central 158A GeV Pb+Pb collisions by the WA98 experiment at CERN. A substantial contribution of the genuine three-body correlation has been found as expected for a mainly chaotic and symmetric source.

The exocellular DD-carboxypeptidase-endopeptidase from Streptomyces albus G. Purification and chemical properties.

The exocellular DD-carboxypeptidase-endopeptidase of Streptomyces albus G was purified to protein homogeneity and compared with the exocellular DD-carboxypeptidases-transpeptidases of Streptomyces R61 and Actinomadura R39. The S. albus G enzyme, as it is isolated, occurs in two forms. Enzyme I (30% of the total amount) and enzyme II (70% of the total amount) are identical in all respects, except that, by polyacrylamide-gel electrophoresis in the presence of sodium dodecyl sulphate, enzyme I has an apparent mol. wt. (9000) that is half of that found by molecular-sieve filtration under non-denaturing conditions. Irrespective of the technique used, enzyme II has an apparent mol. wt. of about 18500.

The exocellular DD-carboxypeptidase-endopeptidase of Streptomyces albus G. Interaction with beta-lactam antibiotics.

Kinetically, the three-step model proposed for the interaction between beta-lactam antibiotics and the exocellular DD-carboxypeptidases-transpeptidases of Streptomyces R61 and Actinomadura R39 [Frère, Ghuysen & Iwatsubo (1975) Eur. J. Biochem. 57, 343--357; Fuad, Frère, Ghuysen, Duez & Iwatsubo (1976) Biochem. J. 155, 623--629] applies to the interaction between the much less penicillin-sensitive exocellular DD-carboxypeptidase-endopeptidase of Streptomyces albus G and at least phenoxymethylpenicillin, cephalothin and cephalosporin C. The penicillin resistance of the albus G enzyme is mainly due to the low efficiency with which the first reversible complex formed with the antibiotic (complex EI) undergoes transformation into a second more stable complex EI*. Analysis of the ternary interaction between enzyme, NalphaNepsilon-diacetyl-L-lysyl-D-alanyl-D-alanine (Ac2-L-Lys-D-Ala-D-Ala) and cephalosporin C indicates a non-competitive mechanism.