| 1. |
- Ablikim, M., et al.
(författare)
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Measurements of (XcJ)-> K+K-K+K- decays
- 2006
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Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 642:3, s. 197-202
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Tidskriftsartikel (refereegranskat)abstract
- Using 14M psi(2S) events taken with the BESII detector, chi(cJ) -> 2(K+K-) decays are studied. For the four-kaon final state, the branching fractions are B(chi(c0,1,2) ->.2(K+K-)) = (3.48 +/- 0.23 +/- 0.47) x 10(-3), (0.70 +/- 0.13 +/- 0.10) x 10(-3), and (2.17 +/- 0.20 +/- 0.31) x 10(-3). For the phi K+K- final state, the branching fractions, which are measured for the first time, are B(chi(c0,1,2) -> phi K+K-) = (1.03 +/- 0.22 +/- 0.15) x 10(-3), (0.46 +/- 0.16 +/- 0.06) x 10(-3), and (1.67 +/- 0.26 +/- 0.24) x 10(-4). For the phi phi final state, B(chi(c0,2) -> phi phi) = (0.94 +/- 0.21 +/- 0.13) x 10(-3) and (1.70 +/- 0.30 +/- 0.25) x 10(-3).
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| 2. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 3. |
- Yu, G., et al.
(författare)
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Structures, electronic states, photoluminescence, and carrier transport properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles
- 2005
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 127:17, s. 6335-6346
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Forskningsöversikt (refereegranskat)abstract
- The excellent electroluminescent (EL) properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles, 1-methyl-1,2,3,4,5-pentaphenylsilole (MPPS), and 1,1,2,3,4,5-hexaphenylsilole (HPS) have been found. Despite some studies devoted to these materials, very little is known about the real origin of their unique EL properties. Therefore, we investigated the structures, photoluminescence (PL), and charge carrier transport properties of 1,1-disubstituted 2,3,4,5-tetraphenylsiloles as well as the effect of substituents on these characteristics. The single crystals of the three siloles involving 1,1-dimethyl-2,3,4,5-tetraphenylsilole (DMTPS), MPPS, and HIPS were grown and their crystal structures were determined by X-ray diffraction. Three siloles have nonplanar molecular structures. The substituents at 1,1-positions enhance the steric hindrance and have predominant influence on the twisted degree of phenyl groups at ring carbons. This nonplanar structure reduces the intermolecular interaction and the likelihood of excimer formation, and increases PL efficiency in the solid state. The silole films show high fluorescence quantum yields (75-85%), whereas their dilute solutions exhibit a faint emission. The electronic structures of the three siloles were investigated using quantum chemical calculations. The highest occupied molecular orbitals (HOMOs) and the lowest unoccupied molecular orbitals (LUMOs) are mainly localized on the silole ring and two phenyl groups at 2,5-positions in all cases, while the LUMOs have a significant orbital density at two exocyclic Si-C bonds. The extremely theoretical studies of luminescent properties were carried out. We calculated the nonradiative decay rate of the first excited state as well as the radiative one. It is found that the faint emission of DMTPS in solutions mainly results from the huge nonradiative decay rate. In solid states, molecular packing can remarkably restrict the intramolecular rotation of the peripheral side phenyl ring, which has a large contribution to the nonradiative transition process. This explains why the 1,1-disubstituted 2,3,4,5-tetraphenylsiloles in the thin films exhibit high fluorescence quantum yields. The charge carrier mobilities of the MPPS and HPS films were measured using a transient EL technique. We obtained a mobility of 2.1 x 10(-6) cm(2)/V(.)s in the MPPS film at an electric field of 1.2 x 10(6) V/cm. This mobility is comparable to that of Alq(3), which is one of the most extensively used electron transport materials in organic light-emitting diodes (LEDs), at the same electric field. The electron mobility of the HPS film is about similar to 1.5 times higher than that of the MPPS film. To the best of our knowledge, this kind of material is one of the most excellent emissive materials that possess both high charge carrier mobility and high PL efficiency in the solid states simultaneously. The excellent EL performances of MPPS and HPS are presumably ascribed to these characteristics.
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| 4. |
- Hou, Yuanyuan, et al.
(författare)
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Pressure-induced polymerization of nano- and submicrometer C60 rods into a rhombohedral phase
- 2006
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Ingår i: Chemical Physics Letters. - : Elsevier BV. - 0009-2614. ; 423:1-3, s. 215-219
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Tidskriftsartikel (refereegranskat)abstract
- C-60 rods with nano- and submicrometer dimensions were polymerized at 4.5 GPa and 973 K. Raman spectroscopy showed that the material transformed into a rhombohedral polymeric structure under high pressure and high temperature (HPHT) conditions. The HPHT polymerized samples keep the original rod shape. The position dependence of photoluminescence (PL) spectra have been studied on the rhombohedral polymer C60 rods at room temperature. The intensity of the 1.74 eV peak from the rhombohedral phase varies systematically between the edge of and the middle of the rod. Our results indicate that the 1.74 eV peak originates from surface defects.
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| 5. |
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| 6. |
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| 7. |
- Brooks, BR, et al.
(författare)
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CHARMM: the biomolecular simulation program
- 2009
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Ingår i: Journal of computational chemistry. - : Wiley. - 1096-987X .- 0192-8651. ; 30:10, s. 1545-1614
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Tidskriftsartikel (refereegranskat)
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| 8. |
- Hartley, D. J., et al.
(författare)
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Wobbling mode in Ta-167
- 2009
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 80:4
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Tidskriftsartikel (refereegranskat)abstract
- The collective wobbling mode, the strongest signature for the rotation of a triaxial nucleus, has previously been seen only in a few Lu isotopes in spite of extensive searches in nearby isotopes. A sequence of transitions in the N = 94 Ta-167 nucleus exhibiting features similar to those attributed to the wobbling bands in the Lu nuclei has now been found. This band feeds into the pi i(13/2) band at a relative energy similar to that seen in the established wobbling bands and its dynamic moment of inertia and alignment properties are nearly identical to the i(13/2) structure over a significant frequency range. Given these characteristics, it is likely that the wobbling mode has been observed for the first time in a nucleus other than Lu, making this collective motion a more general phenomenon.
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| 9. |
- Luo, Guogang, et al.
(författare)
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ERK1/2 pathway involved in the expression of ETB receptors of the culturing smooth muscle cells of rat mesenteric artery
- 2006
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Ingår i: Yao Xue Xue Bao. - 0513-4870. ; 41:3, s. 257-262
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To determine the involvement of extracellular signal-regulated kinase 1/2 (ERK1/2) pathway in the expression of endothelin receptor type B (ETB) during culture. METHODS: SB386023, a specific inhibitor for ERK1/2 pathway, was used to define the intracellular signaling pathway for the upregulation of ETB receptors and sarafotoxin 6c (S6c), a selective agonist for ETB receptors, induced contraction in isolated rat superior mesenteric arteries. The contraction was recorded by a sensitive in vitro myograph and the receptor mRNA was quantified by a real-time PCR. The phosphorylated ERK1/2 proteins were analyzed by phosphoELISA assay. RESULTS: S6c induced strong contractile responses of the artery after culture for 24 h, while there was no response to S6c in fresh vessel segments. The enhanced contractile response to S6c paralleled with an increase of mRNA for ETB receptors. The phosphorylated ERK1/2 proteins significantly increased after culture for 3 h. After co-culture with SB386023 for 24 h, S6c-induced contractions significantly decreased with reduction of Emax from (217 +/- 14) % to (127 +/- 23) % (P <0.01). This response paralleled with a decreased level of ETB receptor mRNA. CONCLUSION: ERK1/2 pathway was involved in the up-regulation of ETB receptors on smooth muscle cells isolated from rat mesenteric arteries during culture.
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| 10. |
- Wang, Wei-Zhou, et al.
(författare)
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Comparative analysis of gene expression profiles between the normal human cartilage and the one with endemic osteoarthritis.
- 2009
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Ingår i: Osteoarthritis and Cartilage. - : Saunders Elsevier. - 1063-4584 .- 1522-9653. ; 17:1, s. 83-90
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the differences in gene expression profiles of adult articular cartilage with endemic osteoarthritis (OA), Kashin-Beck disease (KBD), and the same regions in the normal joint.METHODS: The messenger RNA expression profiles of articular cartilage with KBD diagnosed according to "Diagnosing Criteria of Kashin-Beck Disease in China" were compared with the normal cartilage. Total RNA isolated separately from four pairs of the KBD and normal cartilage samples were evaluated by oligonucleotide microarray analysis. The microarray data were confirmed by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) amplification and were compared with previously published experiments.RESULTS: About 4100 transcripts, which corresponded to 35% of the expressed transcripts, showed >or=twofold differences in expression between the cartilage tissues in pairs. Approximately 2% of the expressed genes (79, 55 genes expressed in KBD>normal; 24 genes expressed in KBDCONCLUSION: Differences between KBD cartilage and the normal exhibited a similar pattern among the four pairs examined, indicating the presence of common mechanisms mainly including chondrocyte metabolism and apoptosis that contribute to cartilage destruction in KBD.
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