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Now showing items 1 - 16 of 2330

  • Brilliant GeV gamma-ray flash from inverse Compton scattering in the QED regime

    Gong, Z.   Hu, R. H.   Lu, H. Y.   Yu, J. Q.   Wang, D. H.   Fu, E. G.   Chen, C. E.   He, X. T.   Yan, X. Q.  

    An all-optical scheme is proposed for studying laser plasma based incoherent photon emission from inverse Compton scattering in the quantum electrodynamic regime. A theoretical model is presented to explain the coupling effects among radiation reaction trapping, the self-generated magnetic field and the spiral attractor in phase space, which guarantees the transfer of energy and angular momentum from electromagnetic fields to particles. Taking advantage of a prospective similar to 10(23) W cm(-2) laser facility, 3D particle-in-cell simulations show a gamma-ray flash with unprecedented multi-petawatt power and brightness of 1.7 x 10(23) photons s(-1) mm(-2) mrad(-2)/0.1% bandwidth (at 1 GeV). These results bode well for new research directions in particle physics and laboratory astrophysics exploring laser plasma interactions.
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  • Circulating Tumor Cells and PET

    Yu, J. Q.   Cristofanilli, M.  

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  • Microfluidic droplet grating for reconfigurable optical diffraction

    Yu, J. Q.   Yang, Y.   Liu, A. Q.   Chin, L. K.   Zhang, X. M.  

    This Letter presents a reconfigurable optical diffraction grating using multiphase droplets on a microfluidic chip. The uniform and evenly spaced circular droplets are generated by continuously dispersing two immiscible liquids into a T junction to produce plugs, which are then transformed into a circular shape at a sudden expansion of the microchannel. In experiments, the droplet grating shows a detection limit of similar to 6.3 x 10(-5) when used as an optofluidic refractometer and produces different colors as a color filter. Such a grating has the advantages of high stability and wide tunability in droplet size, grating period, and refractive index, making it promising for biochemical and biomaterial applications. (C) 2010 Optical Society of America
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  • Allelochemicals and photosynthesis

    Zhou, Y. H.   Yu, J. Q.  

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  • Droplet optofluidic imaging for λ-bacteriophage detection via co-culture with host cell Escherichia coli

    Yu, J. Q.   Huang, W.   Chin, L. K.   Lei, L.   Lin, Z. P.   Ser, W.   Chen, H.   Ayi, T. C.   Yap, P. H.   Chen, C. H.   Liu, A. Q.  

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  • Effects of the plasma profiles on photon and pair production in ultrahigh intensity laser solid interaction

    Tian, Y. X.   Jin, X. L.   Yan, W. Z.   Yu, J. Q.   Li, J. Q.   Li, B.  

    The model of photon and pair production in strong field quantum electrodynamics is implemented into our 1D3V particle-in-cell code with Monte Carlo algorithm. Using this code, the evolution of the particles in ultrahigh intensity laser (similar to 10(23) W/cm(2)) interaction with aluminum foil target is observed. Four different initial plasma profiles are considered in the simulations. The effects of initial plasma profiles on photon and pair production, energy spectra, and energy evolution are analyzed. The results imply that one can set an optimal initial plasma profile to obtain the desired photon distributions. (C) 2015 AIP Publishing LLC.
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  • Preparative Separation of Flavanones and Terpenoids from Olibanum by High-Speed Counter-Current Chromatography

    Zhao, H. W.   Geng, Y. L.   Zhu, H.   Yang, P.   Yu, J. Q.  

    Seven compounds, including two flavanones, dihydrokaempferol (1) and naringenin (2), and five terpenoids, boscartol A (3), 3,7-dioxo-tirucalla-8,24-dien-21-oic acid (4), 3 alpha-acetoxyl-7-oxo-tirucalla-8,24-dien-21-oic acid (5), 11-keto-beta-boswellic acid (6), and acetyl-11-keto-boswellic acid (7), have been purified by high-speed counter-current chromatography (HSCCC) from olibanum. For the separation, from 250 mg of the crude extract, 3.1 mg of 1 (95.2% purity), 2.7 mg of 2 (96.1% purity), 9.1 mg of 3 (96.7% purity), 4.5 mg of 4 (95.3% purity), 5.4 mg of 5 (96.3% purity), 48.1 mg of 6 (96.8% purity), and 45.5 mg of 7 (98.1% purity) were obtained by HSCCC with petroleum ether-ethyl acetate-methanol-water (1:0.8:1.1:0.6, v/v). The structures of these seven compounds were elucidated by a combination of electrospray ionization mass spectrometry (ESI-MS) and extensive nuclear magnetic resonance (NMR) spectroscopic.
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  • The generation of collimated gamma-ray pulse from the interaction between 10 PW laser and a narrow tube target

    Yu, J. Q.   Hu, R. H.   Gong, Z.   Ting, A.   Najmudin, Z.   Wu, D.   Lu, H. Y.   Ma, W. J.   Yan, X. Q.  

    A scheme to radiate a highly collimated gamma-ray pulse is proposed through the interaction between an ultra-intense laser pulse and a narrow tube target. The gamma-ray pulse, with high conversion efficiency, can be generated as a result of electron acceleration in a longitudinal electric field. In a Particle-inCell simulation with a 10-PW laser, 18% of the laser energy is transferred into the forward gamma-ray in a divergence angle less than 3 degrees. It is also found that such a highly collimated gamma-ray pulse can be produced with a large range of tube diameters and laser intensities. This scheme could be realized in experiment with the coming 10-PW class lasers in the near future. Published by AIP Publishing.
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  • Effects of root temperature on leaf gas exchange and xylem sap abscisic acid concentrations in six Cucurbitaceae species

    Zhang, Y. P.   Qiao, Y. X.   Zhang, Y. L.   Zhou, Y. H.   Yu, J. Q.  

    Roots of six Cucurbitaceae species were exposed to low (14 degrees C), middle (24 degrees C), and high (34 degrees C) temperatures while aerial parts of plants were maintained at ambient temperatures between 23 and 33 degrees C. The highest dry mass (DM), photon-saturated rate of net photosynthesis (P(Nsat)), and stomatal conductance (g(s)) were found at 14 degrees C in figleaf gourd and turban squash plants, at 24 degrees C in cucumber and melon plants, while bitter melon and wax gourd plants had lower DM, P(Nsat), and g(s) at 14 degrees C than at 24 or 34 degrees C. Sub-or supra-optimum root temperatures did not induce photoinhibition but induced slight changes in the quantum efficiency of photosystem 2, PS2 (Phi(PS2)) and photochemical quenching(q(p)). Meanwhile, xylem sap abscisic acid (ABA) concentration followed a contrastingchange pattern to that of g(s). Thus the change in P(Nsat) was mainly due to the change in g(s) and roots played an important role in the regulation of stomatal behaviour by deliveringincreased amount of ABA to shoots at sub-or supra-optimum root temperatures.
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  • The role of Ca-2+ and protein kinase C in the acrosome reaction of giant panda (Ailuropoda melanoleuca) spermatozoa

    Sun, Q. Y.   Liu, H.   Li, X. B.   Song, X. F.   Yu, J. Q.   Li, G. H.   Chen, D. Y.  

    Fresh semen was collected from adult male giant pandas and the rote of Ca-2+, Ca-2+ ionophore A23187 and protein kinase C (PKC) in sperm motility and acrosome reaction (AR) was assessed by lens culinaris agglutinin conjugated with fluorescein isothiocyanate (FITC-LCA) labeling and transmission electron microscopy. The AR in giant panda spermatozoa was characterized by vesiculation of the outer acrosomal membrane through its invagination. Both the sperm motility and the AR rate decreased significantly (p lt 0.05) in Ca-2+-free and low Ca-2+ medium. The addition of 10 mu-M Ca-2+ ionophore A23187 potently stimulated AR. After incubation for capacitation, the PKC activator phorbol 12-myristate 13-acetate (PMA) stimulated AR in a dose-dependent manner and its effect could be overcome by the PKC inhibitor staurosporine. These results suggest that Ca-2+ and PKC play an important role in the sperm acrosome reaction of the giant panda.
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  • Crush Thoracic Trauma in the Massive Sichuan Earthquake: Evaluation with Multidetector CT of 215 Cases (vol 254, pg 285, 2010)

    Dong, Z. H.   Yang, Z. G.   Chen, T. W.   Feng, Y. C.   Chu, Z. G.   Yu, J. Q.   Bai, H. L.   Wang, Q. L.  

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  • Q&A Daniel J. Povinelli

    Barker, K. Brandon   Povinelli, Daniel J.  

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  • Guan Yu: The Religious Afterlife of a Failed Hero, by Barend J. ter Haar

    Burton-Rose, Daniel  

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  • Q&A With Dr. Fabian J. David

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  • Q&A With Dr. Fabian J. David

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  • The Infinity of You & Me by J. Q. Coyle

    Quealy-Gainer, Kate  

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