Mass spectral fingerprints of detergents in gasolines using electrospray ionization

Mass spectral fingerprints of detergents in Austrian, Hungarian, Uruguayan, and Chilean gasolines have been obtained using electrospray ionization mass spectrometry. Polymers or copolymers were observed based on ether motifs (inter-peak spacings of 44, 58 and 72 u) in all samples. Austrian gasoline was found to also contain polymers based on isobutene-amine.     

Q2 evolution of the neutron spin structure moments using a 3He target

We have measured the spin structure functions g(1) and g(2) of 3He in a double-spin experiment by inclusively scattering polarized electrons at energies ranging from 0.862 to 5.058 GeV off a polarized 3He target at a 15.5 degrees scattering angle. Excitation energies covered the resonance and the onset of the deep inelastic regions. We have determined for the first time the Q2 evolution of Gamma(1)(Q2)= integral (1)(0)g(1)(x,Q2)dx, Gamma(2)(Q2)= integral (1)(0)g(2)(x,Q2)dx, and d(2)(Q2)= integral (1)(0)x(2)[2g(1)(x,Q2)+3g(2)(x,Q2)]dx for the neutron in the range 0.1< or =Q2< or =0.9 GeV2 with good precision. Gamma(1)(Q2) displays a smooth variation from high to low Q2. The Burkhardt-Cottingham sum rule holds within uncertainties and d(2) is nonzero over the measured range.     

Q2 evolution of the generalized Gerasimov-Drell-Hearn integral for the neutron using a 3He target

We present data on the inclusive scattering of polarized electrons from a polarized 3He target at energies from 0.862 to 5.06 GeV, obtained at a scattering angle of 15.5 degrees. Our data include measurements from the quasielastic peak, through the nucleon resonance region, and beyond, and were used to determine the virtual photon cross-section difference sigma(1/2)-sigma(3/2). We extract the extended Gerasimov-Drell-Hearn integral for the neutron in the range of four-momentum transfer squared Q2 of 0.1-0.9 GeV2.     

Selective hydrogenation of o-xylene on noble metals: Thermal effect in selectivity

Selective hydrogenation of o-xylene on silica supported noble metals Pd, Rh, Ni, Pt, Ir, Ru, Os and Re has been studied. A correlation between the heat capacity of the metal conduction electrons and the selectivity towards the cis-product was found. Thermal effect in activity and selectivity is reported.

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- Pd, Rh, Ni, Pt, Ir, Ru, Os Re, Al₂O₃. -. .

     

Alkoxyamines of Stable Aromatic Nitroxides: N?O vs. C?O Bond Homolysis

A series of stable 2,2‐disubstituted 3‐(phenylimino)indol‐1‐oxyls, the alkoxyamines 3 , were prepared, characterized, and tested as possible candidates in controlled radical polymerization (CRP). The sturctures of 3d and 10 were additionally solved by X‐ray diffraction. The lability of the N? O(C) and (N)O? C bonds of compounds 3 were compared, and the possibility of N? O vs. O? C bond cleavage was evaluated by thermal degradation, ESR spin trapping, MS experiments, and DFT calculations. Alkoxyamines with a primary‐ or secondary‐alkyl group bound to the O‐atom of the nitroxide function (hexyl and i‐Pr) mainly underwent (undesired) N? O bond homolysis. When the O‐alkyl radical was a tertiary or a benzyl group (crotonyl or styryl), O? C bond cleavage occurred as the main process, thus suggesting a possible use of these compounds in CRP processes.     

Theoretical study of the H(2) reaction with a Pt(4) (111) cluster

The C(s) symmetry reaction of the H(2) molecule on a Pt(4) (111) clusters, has been studied using ab initio multiconfiguration self-consistent field plus extensive multireference configuration interaction variational and perturbative calculations. The H(2) interaction by the vertex and by the base of a tetrahedral Pt(4) cluster were studied in ground and excited triplet and singlet states (closed and open shells), where the reaction curves are obtained through many avoided crossings. The Pt(4) cluster captures and activates the hydrogen molecule; it shows a similar behavior compared with other Pt(n) (n=1,2,3) systems. The Pt(4) cluster in their lowest five open and closed shell electronic states: (3)B(2), (1)B(2), (1)A(1) (3)A(1), (1)A(1), respectively, may capture and dissociate the H(2) molecule without activation barriers for the hydrogen molecule vertex approach. For the threefolded site reaction, i.e., by the base, the situation is different, the hydrogen adsorption presents some barriers. The potential energy minima occur outside and inside the cluster, with strong activation of the H-H bond. In all cases studied, the Pt(4) cluster does not absorb the hydrogen molecule.     

Effect of tetrabutyltin on the acidity and reducibility of platinum-tin alumina supported sol-gel catalysts

Tin precursor effect in Pt−Sn/Al₂O₃ sol-gel catalysts has been studied. It is shown that catalysts prepared with tetrabutyltin allow a better reduction of platinum than catalysts prepared with tin tetrachloride and with tin tetra-tert-amyloxide. The solids prepared with tetrabutyltin are catalysts showing a high activity in isopropanol decomposition and cyclohexane dehydrogenation.     

Speciation and adsorption of trace-level fission product of 132Te, 95Zr, 99Mo and 103Ru on inorganic materials

The potential uses of hydrous oxides in the treatment of radioactive wastes may be affected by the physical-chemical properties of these materials. The sorption behavior of trace level (less than 10^-14 g/ml) ²³⁵U fission products in aqueous solutions was studied under static conditions on TiO₂, MnO₂ and SnO sorbents. A variety of anions, cations and neutral species of ¹³²Te,⁹⁵Zr, ⁹⁹Mo and ¹⁰³Ru in aqueous solutions at 1, 3, 5, 7 and 10 pH values were identified and their retention values were calculated. High voltage electrophoresis was used to establish the chemical species of these radioisotopes formed in the solution. This revised version was published online in July 2006 with corrections to the Cover Date.     

Pion correlations and resonance effects in [`(p)]p\bar pp annihilation at rest to 2π+2π-π0

We study ππ correlations in the exclusive reaction at rest with complete reconstruction of the kinematics for each event. Inclusive and differential distributions properly normalized show an enhancement for small invariant masses M ₊₊,M _-- of like-pion pairs. An even stronger enhancement is seen for the double differential distributions for low pion-pair masses. The signal is strongest when the π₀ energy is large and much weaker when this energy is small. Dynamical models with resonances in the final state are confronted with the data. For the kinematic situation where the ρ3π channel is important the simulation predicts a large pion correlation for the double differential density, qualitatively explaining the observed bahaviour. The stochastic HBT mechanism is not supported by these findings for the exclusive annihilation reaction studied.     

Enabling continuous-flow chemistry in microstructured devices for pharmaceutical and fine-chemical production

Microstructured devices offer unique transport capabilities for rapid mixing, enhanced heat and mass transfer and can handle small amounts of dangerous or unstable materials. The integration of reaction kinetics into fluid dynamics and transport phenomena is essential for successful application from process design in laboratory to chemical production. Strategies to implement production campaigns up to tons of pharmaceutical chemicals are discussed, based on Lonza projects.