Strange particle production at the intersection of soft and hard processes at RHIC

Nuclear suppression factor and u ₂ measurements as a function of transverse momentum for neutral strange particles are shown and compared to particle identified spectra from PHENIX and WA98 and to models that attempt to describe the suppression of particles at moderate pt in central RHIC Au?Au collisions. It is shown that identified spectra carry additional information to the published charged particle spectra. In particular, dependencies of the R _AA and u ₂ values on the measured particle species will be discussed in the context of several models.     

Charge-changing cross sections of the neutron-rich isotopes8,9,11Li

Total charge-changing cross sections have been measured for⁸Li on C and Pb targets, for⁹Li on C, Al, Cu, Sn and Pb targets, as well as for¹¹Li on C, Sn and Pb targets at about 80 MeV/nucleon. These data are compared to measured total reaction cross sections and Glauber-type calculations using Hartree-Fock density distributions. These comparisons allow to draw conclusions on the proton density distribution of the neutronrich lithium isotopes. The results show that even for the most exotic nucleus¹¹Li the proton distribution is only very weakly influenced by the long tail in the neutron density distribution already established in several experiments.     

Application of the program LISE to fusion-evaporation

A new fusion-evaporation model LisFus for fast calculation of fusion residue cross sections has been developed in the framework of the code LISE. This model can calculate very small cross sections quickly compared to programs using the Monte Carlo method. Such type of the fast calculations is necessary to estimate fusion residue yields. Using this model, the program LISE now has the possibility of calculating the transmission of fusion residues through a fragment separator. It is also possible to use fusion residue cross sections calculated by the program PACE, which has been incorporated in the LISE package. The code PACE is a modified version of JULIAN—the Hillman-Eyal evaporation code using a Monte Carlo code coupling angular momentum. A comparison between PACE and the LisFus model is presented.     

Stochastic Arithmetic: s-spaces and Some Applications

It has been recently shown that computation with stochastic numbers as regard to addition and multiplication by scalars can be reduced to computation in familiar vector spaces. In this work we show how this can be used for the algebraic solution of linear systems of equations with stochastic right-hand sides. On several examples we compare the algebraic solution with the simulated solution using the CADNA package.     

Polyfluorothiolate derivatives of rhodium(I). Crystal and molecular structure of [Rh(μ-SC6HF4)(C8H12)]2

Summary The thiolato-bridged dinuclear compounds [Rh(-SR)-(COD)]₂, where R=p-C₆HF₄ (1),p-C₆H₄F (2) and CF₃ (3), are obtained from the chloro-bridged analogue by ligand exchange.Compound (1) crystallizes in the space group P₁ with a=9.740(3)Å, b=11.642(4)Å, c=13.997(6)Å, =103.87(3)°, =106.98(3)° and =105.10(2)°; z=2. In this dinuclear molecule both Rh atoms have a square planar coordination sharing one edge, namely the two sulphur bridging atoms. The Rh—Rh separation of 2.96 Å is consistent with at most a very weak metal-metal interaction. Upon addition of CO the dimeric [Rh(-SR)(CO)₂]₂ (4), (5) and (6) are obtained, but addition of PPh₃ affords the monomeric species [Rh(SR)(PPh₃)-(COD)] (7), (8) and (9). Reactions of the dimeric tetracarbonyl derivatives with PPh₃ vary with the nature of R; [Rh(-SR)(PPh₃)(CO)]₂ is obtained when R=p-C₆H₄F (10) and CF₃ (11) but monomeric [Rh(SR)-(PPh₃)(CO)₂] (12) is produced when R=p-C₆HF₄. The latter mononuclear compounds, with R=p-C₆H₄F (13) and CF₃ (14), are also formed by reaction of [Rh(SR)-(PPh₃)(COD)] with CO.     

SUPEROXIDE DISMUTASE AS AN AMPLIFIER OF THE CHEMICAL REACTIVITY OF PORPHYRIN RADICAL-CATIONS

Abstract— Porphyrin radical-cations have been produced using laser flash photolysis via oxidation of the porphyrin triplets by metronidazole. This radical-cation reacts with OJ as shown by its increased half-life in the presence of native superoxide dismutase. Comparable results are obtained when porphyrin radical-cations are formed by Br₂^-O₂^-oxidation of porphyrins produced in pulse radiolysis of oxygen-saturated aqueous solutions containing 20 mM Br^-O^-. These results provide an explanation for the enhancement by superoxide dismutase of the photosensitizing capacity of porphyrins in the presence of electrophilic nitroimidazoles (Bazin and Santus, 1986). They may also apply to porphyrin radical-cations formed by monophotonic or biphotonic photoionization processes.     

Characterisation of Sugar Cane Combustion Particles in the Araraquara Region, Southeast Brazil

Biomass burning is an important primary and secondary source of aerosol particles. The presence of carbonaceous particles in the respirable size range makes the study of this fraction important in view of possible health and climatic effects. The annual burning of sugar cane plantations causes emission of huge amounts of pyrogenic particles. Aerosol samples were collected in Araraquara city, São Paulo state, Brazil, during the harvest season for fine and coarse particles and bulk; they were analysed by electron-probe microanalysis, including facilities for low-Z element determination (low-Z EPMA) and by energy-dispersive X-ray fluorescence (EDXRF), in order to investigate the elemental composition of individual particles and bulk samples, respectively. Numerical analysis of the EPMA results by hierarchical clustering shows high contributions of carbonaceous particles that can be distinguished mainly in two different types: biogenic and carbon-rich. Additionally, two significant contributions of aluminosilicate particles were identified: as rather pure aluminosilicates or mixed with carbonaceous species. The EDXRF results are compatible with those of aerosol particles in Amazon, which is nowadays one of the main sources of biogenic particles in the world.