| 1. |
- Aaron, F. D., et al.
(författare)
-
Multi-leptons with high transverse momentum at HERA
- 2009
-
Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :10
-
Tidskriftsartikel (refereegranskat)abstract
- Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb(-1). The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e(+)p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94 +/- 0.17 events are expected. Such events are not observed in e(-)p collisions for which 1.19 +/- 0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions.
|
|
| 2. |
- Matxain, Jon M, et al.
(författare)
-
New solids based on B12N12 fullerenes
- 2007
-
Ingår i: The Journal of Physical Chemistry C. - Washington, DC : American Chemical Society. - 1932-7447 .- 1932-7455. ; 111:36, s. 13354-60
-
Tidskriftsartikel (refereegranskat)abstract
- In recent years, BN fullerenes have been synthesized experimentally. As their carbon counterparts, these BN fullerenes could be assembled in molecular solids, but this possibility has been studied little in the literature. In this work, we focus on the smallest synthesized BN fullerene, B12N12, which is built by squares and hexagons. First, the interaction between two of these fullerenes has been analyzed, using the hybrid B3LYP and MPW1PW91 density functional methods. Two different interactions have been studied in the dimer, a square facing a square (S−S) and a hexagon facing a hexagon (H−H). In both cases, a B is facing a N. The most stable dimer was found to be S−S facing, with covalent interactions between the monomers, but other dimers with weak interactions have been found as well, which opens possibilities of new systems, as in the case of fullerene dimers and solids. The solids resulting from the infinite repetition of the characterized dimers were optimized, finding two different solids, with covalent and weak interactions between monomers, respectively. The solid with covalent interactions is a nanoporous material that is more stable by around 12 eV. Because of the nanoporous character of this solid, it could be used for heterogeneous catalysis, molecular transport, and so forth. The SIESTA code with the GGA-PBE density functional method has been used for the solid-state calculations.
|
|
| 3. |
|
|
| 4. |
- Guell, Mireia, et al.
(författare)
-
Theoretical study of the hydroxylation of phenolates by the Cu2O2(N,N '-dimethylethylenediamine)(2)(2+) complex
- 2009
-
Ingår i: Journal of Biological Inorganic Chemistry. - : Springer Science and Business Media LLC. - 0949-8257 .- 1432-1327. ; 14:2, s. 229-242
-
Tidskriftsartikel (refereegranskat)abstract
- Tyrosinase catalyzes the ortho hydroxylation of monophenols and the subsequent oxidation of the diphenolic products to the resulting quinones. In efforts to create biomimetic copper complexes that can oxidize C-H bonds, Stack and coworkers recently reported a synthetic mu-eta(2):eta(2)-peroxodicopper(II)(DBED)(2) complex ( DBED is N,N'-di-tert-butylethylenediamine), which rapidly hydroxylates phenolates. A reactive intermediate consistent with a bis-mu-oxo-dicopper(III)-phenolate complex, with the O-O bond fully cleaved, is observed experimentally. Overall, the evidence for sequential O-O bond cleavage and C-O bond formation in this synthetic complex suggests an alternative mechanism to the concerted or late-stage O-O bond scission generally accepted for the phenol hydroxylation reaction performed by tyrosinase. In this work, the reaction mechanism of this peroxodicopper(II) complex was studied with hybrid density functional methods by replacing DBED in the mu-eta(2):eta(2)-peroxodicopper(II)(DBED)(2) complex by N,N'-dimethylethylenediamine ligands to reduce the computational costs. The reaction mechanism obtained is compared with the existing proposals for the catalytic ortho hydroxylation of monophenol and the subsequent oxidation of the diphenolic product to the resulting quinone with the aim of gaining some understanding about the copper-promoted oxidation processes mediated by 2: 1 Cu(I)O-2-derived species.
|
|
| 5. |
- Guell, Mireia, et al.
(författare)
-
Theoretical study of the hydroxylation of phenols mediated by an end-on bound superoxo-copper(II) complex
- 2009
-
Ingår i: Journal of Biological Inorganic Chemistry. - : Springer Science and Business Media LLC. - 0949-8257 .- 1432-1327. ; 14:2, s. 273-285
-
Tidskriftsartikel (refereegranskat)abstract
- Peptidylglycine alpha-amidating monooxygenase and dopamine beta-monooxygenase are copper-containing proteins which catalyze essential hydroxylation reactions in biological systems. There are several possible mechanisms for the reductive O-2-activation at their mononuclear copper active site. Recently, Karlin and coworkers reported on the reactivity of a copper(II)-superoxo complex which is capable of inducing the hydroxylation of phenols with incorporated oxygen atoms derived from the Cu(II)-O-2(-) moiety. In the present work the reaction mechanism for the abovementioned superoxo complex with phenols is studied. The pathways found are analyzed with the aim of providing some insight into the nature of the chemical and biological copper-promoted oxidative processes with 1:1 Cu(I)/O-2-derived species.
|
|
| 6. |
- Heinat, Fredrik, et al.
(författare)
-
Probing phrases, pronouns and binding
- 2009
-
Ingår i: Merging Features : Computation, Interpretation, and Acquisition - Computation, Interpretation, and Acquisition. - : Oxford University PressOxford. - 9780199553266 - 9780191720833 ; , s. 25-45
-
Bokkapitel (refereegranskat)abstract
- This chapter makes use of Pesetsky and Torrego's feature chains to account for the distribution of reflexive and personal pronouns. Under the assumption that all unvalued features probe when merged, it is possible to form chains between reflexives and their antecedents. In line with Reuland (2001), the assumption is that these chains force the reflexives to be interpreted as bound variables at LF.
|
|
