| 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. |
- Gao, Feng, et al.
(författare)
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Effects of substrate temperature on Bi0.8La0.2FeO3 thin films prepared by pulsed laser deposition
- 2007
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Ingår i: Thin Solid Films. - : Elsevier. - 0040-6090 .- 1879-2731. ; 515:13, s. 5366-5373
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Tidskriftsartikel (refereegranskat)abstract
- Bi0.8La0.2FeO3 thin films on Pt/TiO2/SiO2/Si substrates at various substrate temperatures from 500 degrees C to 750 degrees C are prepared by pulsed laser deposition, and their microstructures and ferroelectric/magnetic properties are carefully investigated using various techniques. It is observed that the crystallographic orientation and Fe-ion valence state depend significantly on the substrate temperature, which consequently influences considerably on the ferroelectric and magnetic properties of the thin films. A considerable improvement of the ferroelectric and magnetic properties of the thin films can be achieved by optimizing the substrate temperature for deposition. (C) 2007 Elsevier B.V. All rights reserved.
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| 3. |
- Yu, Ling-Zhu, et al.
(författare)
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MEK1/2 regulates microtubule organization, spindle pole tethering and asymmetric division during mouse oocyte meiotic maturation.
- 2007
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Ingår i: Cell cycle (Georgetown, Tex.). - 1551-4005. ; 6:3, s. 330-8
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that MAPK plays pivotal roles in oocyte maturation, but the function of MEK (MAPK kinase) remains unknown. We have studied the expression, subcellular localization and functional roles of MEK during meiotic maturation of mouse oocytes. Firstly, we found that MEK1/2 phoshorylation (p-MEK1/2, indicative of MEK activation) was low in GV (germinal vesicle) stage, increased 2h after GVBD (germinal vesicle breakdown), and reached the maximum at metaphase II. Secondly, we found that P-MEK1/2 was restricted in the GV prior to GVBD. In prometaphase I and metaphase I, P-MEK1/2 was mainly associated with the spindle, especially with the spindle poles. At anaphase I and telophase I, p-MEK1/2 became diffusely distributed in the region between the separating chromosomes, and then became associated with the midbody. The association of p-MEK1/2 with spindle poles was further confirmed by its colocalization with the centrosomal proteins, gamma-tubulin and NuMA. Thirdly, we have investigated the possible functional role of MEK1/2 activation by intravenous administration and intrabursal injection of a specific MEK inhibitor, U0126, and by microinjection of MEK siRNA into oocytes. All these manipulations cause disorganized spindle poles and spindle structure, misaligned chromosomes and larger than normal polar bodies. Our results suggest that MEK1/2 may function as a centrosomal protein and may have roles in microtubule organization, spindle pole tethering and asymmetric division during mouse oocyte maturation.
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| 4. |
- Chen, Baowei, et al.
(författare)
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Simulate methylation reaction of arsenic(III) with methyl iodide in an aquatic system
- 2006
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Ingår i: Applied organometallic chemistry. - : John Wiley & Sons. - 0268-2605 .- 1099-0739. ; 20:11, s. 747-753
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Tidskriftsartikel (refereegranskat)abstract
- The methylation reaction of inorganic arsenic occurring in aquatic systems was studied by HPLC-HGAFS as a method to separate and detect soluble methylarsenic species. Transformation from inorganic arsenic to methylarsenic was essential for major changes in toxicity to organisms. Monomethylarsenic [AsOCH(3)(OH)(2)] was the only product in the methylation reaction of inorganic arsenic(III) with methyl iodide (MeI). This process can be described as an oxidative carbonium-ion transfer, with MeI acting as a methyl donor. From a thermodynamic point of view, the activity of the carbonium ion and pH were the two major influencing factors. The pH dependence of redox potential of As(III) was the reason for the effect of pH on methylation of arsenic. The influences of salinity and concentration of the methyl donor may be explained by their effects on the activity of carbonium. Moreover, kinetics experiments demonstrated that the methylation reaction was first-order for both As(III) and methyl iodide. First-order reaction rates were also calculated at different pH, salinity and MeI, and were found to be in the range 0.0026-0.0123 h(-1). The methylation rate varied largely under different reaction conditions.
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| 5. |
- Chen, K., et al.
(författare)
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High permittivity in zr doped NiO ceramics
- 2007
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 102:3, s. 034103-
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Tidskriftsartikel (refereegranskat)abstract
- We report on measurements of the dielectric permittivity of NiO-based ceramics doped with Zr (ZNO). Samples were prepared by the traditional solid-state reaction method. The concentration of Zr has an effect on the dielectric properties of ZNO ceramics. High permittivity values (similar to 10(4)) were observed which remain almost constant from 200 K to 350 K at low frequencies. The high-dielectric-constant response of the ZNO ceramics is attributed mainly to a grain boundary (internal) barrier layer capacitance. (c) 2007 American Institute of Physics.
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| 6. |
- Gao, Feng, et al.
(författare)
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Preparation and photoabsorption characterization of BiFeO3 nanowires
- 2006
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 89:10, s. 102506-
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Tidskriftsartikel (refereegranskat)abstract
- Perovskite-type polycrystalline BiFeO3 (BFO) nanowires (similar to 50 nm in diameter and similar to 5 mu m in length) were synthesized using the anodized alumina template technique. An energy band gap of similar to 2.5 eV was determined from the UV-visible diffuse reflectance spectrum, and its photocatalytic ability to produce O-2 was revealed under UV irradiation. Weak ferromagnetism at room temperature and superparamagnetism at low temperature were observed for the BFO nanowires, different from the antiferromagnetic order in bulk BFO, reflecting the significant size effects on the magnetic ordering of BFO. (c) 2006 American Institute of Physics.
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| 7. |
- Gao, Feng, et al.
(författare)
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Preparation of la-doped BiFeO3 thin films with Fe2+ ions on Si substrates
- 2006
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 99:9, s. 094105-
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Tidskriftsartikel (refereegranskat)abstract
- La-doped BiFeO3 thin films with Fe2+ ions have been prepared on Pt/TiO2/SiO2/Si substrates by pulsed laser deposition in order to enhance the ferroelectric and magnetic properties. The targets for the film deposition were synthesized using a rapid liquid phase sintering technique to ensure the low leakage. The dielectric properties at room temperature and above were investigated. It was observed that the La doping greatly enhances the ferroelectric polarization at room temperature by modifying the film structure from rhombohedral to monoclinic. The saturation magnetization was enhanced about two times due to the Fe2+ ions in the thin films. (C) 2006 American Institute of Physics.
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| 8. |
- Gao, Feng, et al.
(författare)
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Visible-light photocatalytic properties of weak magnetic BiFeO3 nanoparticles
- 2007
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Ingår i: Advanced Materials. - : Wiley-VCH Verlag. - 0935-9648 .- 1521-4095. ; 19:19, s. 2889-2892
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Tidskriftsartikel (refereegranskat)abstract
- Polycrystalline BiFeO3 nanoparticles (size 80-120 nm) are prepared by a simple sol-gel technique. Such nanoparticles are very efficient for photocatalytic decomposition of organic contaminants under irradiation from ultraviolet to visible frequencies. The BiFeO3 nanoparticles also demonstrate weak ferromagnetism of about 0.06 mu(B)/Fe at room temperature, in good agreement with theoretical calculations.
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| 9. |
- Gao, Shiwu, 1963, et al.
(författare)
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Emergence of collective plasmon excitation in a confined one-dimensional electron gas
- 2005
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Ingår i: PHYSICAL REVIEW B. ; 72:12, s. art. no. 121406-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of the electronic excitation in a confined one-dimensional electron gas, which is utilized to model atomic chains created in recent experiments. The length dependence of the excitation spectra is obtained from the linear response theory within the random phase approximation and time-dependent density functional theory. As the length of the chains increases, the dipole excitation spectra show a transition from electron-hole pair excitations to collective plasmon excitation. The trend of the length-dependent plasmon resonance is predicted, and the nature of the plasmon resonance is also elaborated.
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| 10. |
- Li, Jin Billy, et al.
(författare)
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Multiplex padlock targeted sequencing reveals human hypermutable CpG variations
- 2009
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Ingår i: Genome Research. - : Cold Spring Harbor Laboratory. - 1088-9051 .- 1549-5469. ; 19:9, s. 1606-1615
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Tidskriftsartikel (refereegranskat)abstract
- Utilizing the full power of next-generation sequencing often requires the ability to perform large-scale multiplex enrichment of many specific genomic loci in multiple samples. Several technologies have been recently developed but await substantial improvements. We report the 10,000-fold improvement of a previously developed padlock-based approach, and apply the assay to identifying genetic variations in hypermutable CpG regions across human chromosome 21. From approximately 3 million reads derived from a single Illumina Genome Analyzer lane, approximately 94% (approximately 50,500) target sites can be observed with at least one read. The uniformity of coverage was also greatly improved; up to 93% and 57% of all targets fell within a 100- and 10-fold coverage range, respectively. Alleles at >400,000 target base positions were determined across six subjects and examined for single nucleotide polymorphisms (SNPs), and the concordance with independently obtained genotypes was 98.4%-100%. We detected >500 SNPs not currently in dbSNP, 362 of which were in targeted CpG locations. Transitions in CpG sites were at least 13.7 times more abundant than non-CpG transitions. Fractions of polymorphic CpG sites are lower in CpG-rich regions and show higher correlation with human-chimpanzee divergence within CpG versus non-CpG sites. This is consistent with the hypothesis that methylation rate heterogeneity along chromosomes contributes to mutation rate variation in humans. Our success suggests that targeted CpG resequencing is an efficient way to identify common and rare genetic variations. In addition, the significantly improved padlock capture technology can be readily applied to other projects that require multiplex sample preparation.
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| 11. |
- Liu, J. -M., et al.
(författare)
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Ferroelectric and magnetoelectric behaviors of multiferroic BiFeO3 and piezoelectric-magnetostrictive composites
- 2008
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Ingår i: Journal of Electroceramics. - : Springer Verlag (Germany). - 1385-3449 .- 1573-8663. ; 21:1-4, s. 78-84
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we overview our recent work on ferroelectric and magnetoelectric coupling behaviors of multiferroic doped BiFeO3 (BFO) and piezoelectric-magnetostrictive composites. Using rapid liquid sintering method we prepare single-phase BFO ceramics of excellent ferroelectric property. The BFO thin films on Pt-coated silicon wafers by pulsed laser deposition show large remnant polarization but serious ferroelectric switching fatigue. A series of piezoelectric-magnetostrictive composite structures in bulk and thin film forms are prepared and giant magnetoelectric coupling effect of them is observed. The experimentally measured results are confirmed by numerical modeling based on piezoelectric and magnetostrictive constitution equations.
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| 12. |
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| 13. |
- Yan, Jun, et al.
(författare)
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End and Central Plasmon Resonances in Linear Atomic Chains
- 2007
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Ingår i: Phys. Rev. Lett.. ; 98, s. 216602-
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Tidskriftsartikel (refereegranskat)abstract
- The existence and nature of end and central plasmon resonances in a linear atomic chain, the 1D analog to surface and bulk plasmons in 2D metals, has been predicted by ab initio time-dependent density functional theory. Length dependence of the absorption spectra shows the emergence and development of collectivity of these resonances. It converges to a single resonance in the longitudinal mode, and two transverse resonances, which are localized at the ends and center of the atom chains. These collective modes bridge the gaps, in concept and scale, between the collective excitation of atomic physics and nanoplasmonics. It also outlines a route to atomic-scale engineering of collective excitations.
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| 14. |
- Yuan, F., et al.
(författare)
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Effect of Pr doping on ferroelectric behaviors of Pb(Zr0.65Ti0.35)O-3
- 2008
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Ingår i: International Journal of Modern Physics B. - : WORLD SCIENTIFIC PUBL CO PTE LTD. - 0217-9792. ; 22:13, s. 2070-2081
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Tidskriftsartikel (refereegranskat)abstract
- Pr-doped Pb(Zr0.65Ti0.35)O-3 (Pb1-xPr (Zr0.65Ti0.35)(1-x)/O-4(3), PPZT) ceramic samples are prepared using conventional solid-state sintering method, and their structural, dielectric, ferroelectric, and piezoelectric properties are investigated, focusing on the effects of Pr-doping. Upon increasing Pr doping level x, a transition of the crystallographic structure from rhombohedral symmetry to tetrahedral and finally to pseudocubic symmetry is observed at x similar to 0.08. The detailed dielectric measurements present a clear indication of relaxor-like behaviors at x = 0.08, while the samples at x less than 0.08 offer slightly improved ferroelectric properties compared with pure Pb(Zr0.65Ti0.35)O-3. In spite of the dielectric relaxor behaviors induced by Pr-doping, both the ferroelectric and piezoelectric properties of PPZT are degraded at x = 0.08. The physics underlying the Pr-doping induced relaxor behaviors is then discussed.
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| 15. |
- Yuan, Zhe, 1981, et al.
(författare)
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Landau damping and lifetime oscillation of surface plasmons in metallic thin films studied in a jellium slab model
- 2008
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028. ; 602:2, s. 460-464
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Tidskriftsartikel (refereegranskat)abstract
- The lifetime of surface plasmons in metallic thin films has been calculated using linear response theory and time-dependent local density approximation. The linewidth due to Landau damping is found to depend exponentially on the film thickness. It exhibits quantum oscillations in ultrathin films with a period that is about three times longer than the universal period λF/2 observed in other quantities. This period results from the dynamical Friedel oscillations in the collective excitation normal to the films. Its finding has general implications in quantum control of nanoplasmons and their mediated processes across the films and on their surfaces.
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| 16. |
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| 17. |
- Yuan, Zhe, 1981, et al.
(författare)
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Linear-response study of plasmon excitation in metallic thin films: Layer-dependent hybridization and dispersion
- 2006
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Ingår i: PHYSICAL REVIEW B. ; 73:(15), s. 155411-
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of collective plasmon excitation in metal thin films using the jellium model. The excitation spectra are calculated in the linear response theory and the time-dependent local density approximation. The evolution from surface plasmons at large thickness to the hybridized thin film plasmons at smaller thickness is obtained as functions of atomic layers and electron momenta. The energies of the hybridized plasmons follow qualitatively the classical electrodynamical model at large to intermediate thickness. For ultrathin films with a few atomic layers, these plasmon resonances evolve into intraband and interband transitions at small momenta. The latter results from the quantized electron states normal to the films.
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