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981.
We have imaged a 2D buried Ni nanostructure at 8 nm resolution using coherent x-ray diffraction and the oversampling phasing method. By employing a 3D imaging reconstruction algorithm, for the first time we have experimentally determined the 3D structure of a noncrystalline nanostructured material at 50 nm resolution. The 2D and 3D imaging resolution is currently limited by the exposure time and the computing power, while the ultimate resolution is limited by the x-ray wavelengths. We believe these results pave the way for the development of atomic resolution 3D x-ray diffraction microscopy. 相似文献
982.
Yasunori Saito Koh-jiro Kurihara Hiroaki Takahashi Fumitoshi Kobayashi Takuya Kawahara Akio Nomura Satomi Takeda 《Optical Review》2002,9(2):37-39
Monthly variation in chlorophyll concentration of living ginko tree leaves 65 m away from a system was remotely estimated by a laser-induced fluorescence imaging lidar. The combination of a pulsed laser and a short-time gated CCD using an image intensifier made it possible to monitor the weak fluorescence signal from the ginko tree leaves as an image. By applying the experimental idea that a ratio of intensity of the chlorophyll fluorescence at 740 nm to that at 685 nm showed a linear correlation to the chlorophyll concentration, the fluorescence image of the ginko tree obtained by the lidar was converted to the chlorophyll concentration distribution image. 相似文献
983.
The flow field and the energy transport near thermoacoustic couples are simulated using a 2D full Navier-Stokes solver. The thermoacoustic couple plate is maintained at a constant temperature; plate lengths, which are "short" and "long" compared with the particle displacement lengths of the acoustic standing waves, are tested. Also investigated are the effects of plate spacing and the amplitude of the standing wave. Results are examined in the form of energy vectors, particle paths, and overall entropy generation rates. These show that a net heat-pumping effect appears only near the edges of thermoacoustic couple plates, within about a particle displacement distance from the ends. A heat-pumping effect can be seen even on the shortest plates tested when the plate spacing exceeds the thermal penetration depth. It is observed that energy dissipation near the plate increases quadratically as the plate spacing is reduced. The results also indicate that there may be a larger scale vortical motion outside the plates which disappears as the plate spacing is reduced. 相似文献
984.
Recent progress on time-division multiplexed (TDM) and wavelength-division multiplexed (WDM) soliton transmission is described, in which dispersion management plays an important role in increasing the power margin and the dispersion tolerance. The characteristics of the dispersion-managed soliton are compared with those of return to zero and nonreturn to zero pulses. With a small dispersion swing, the system can still be described as an average soliton using the nonlinear Schrodinger equation, while with a large dispersion swing, the solitonlike steady-state pulse becomes a chirped Gaussian pulse, in which the governing equation is closer to a linear Schrodinger equation with a parabolic potential well. We describe an in-line modulation scheme for up to 80 Gbit/s per channel and its two channel WDM transmission over 10 000 km. Finally, we describe 640 Gbit/s (40 Gbit/sx16 channels) WDM soliton transmission over 1000 km with a dispersion-managed single-mode fiber. (c) 2000 American Institute of Physics. 相似文献
985.
Aoki S Fukugita M Hashimoto S Ishikawa KI Ishizuka N Iwasaki Y Kanaya K Kaneko T Kuramashi Y Okawa M Onogi T Tsutsui N Ukawa A Yamada N Yoshié T;JLQCD Collaboration 《Physical review letters》2003,91(21):212001
We present an unquenched lattice calculation for the B(0)-B(0) transition amplitude. The calculation, carried out at an inverse lattice spacing 1/a=2.22(4) GeV, incorporates two flavors of dynamical quarks described by the O(a)-improved Wilson fermion action and heavy quarks described by nonrelativistic QCD. Particular attention is paid to the uncertainty that arises from the chiral extrapolation, especially the effect of pion loops, for light quarks, which we find could be sizable for the leptonic decay constant, whereas it is small for the B parameters. We obtain f(B(d))=191(10)(+12-22) MeV, f(B(s))/f(B(d))=1.13(3)(+13-2), B(B(d))(m(b))=0.836(27)(+56-62), B(B(s))/B(B(d))=1.017(16)(+56-17), and xi=1.14(3)(+13-2), where the first error is statistical, and the second is systematic, including uncertainties due to chiral extrapolation, finite lattice spacing, heavy quark expansion, and perturbative operator matching. 相似文献
986.
Akio Kawai Shuichi Mori Kazuhide Tsuji Kazuhiko Shibuya 《Applied magnetic resonance》2010,38(2):205-216
Quenching of the triplet excited state of molecular tryptophan by nitroxide radical in 1,4-dioxane and water solutions was
investigated by means of time-resolved electron paramagnetic resonance (EPR) and Fourier-transform (FT)-EPR. The chemically
induced dynamic electron polarization (CIDEP) signals with net emissive phase were recorded at these quenching events and
were analyzed through radical-triplet pair mechanism. The CIDEP time profiles were well reproduced by Bloch and kinetic equations,
assuming radical-triplet pair mechanism with the appropriate quenching rate constants. From a comparison of the simulation
and the experiment, CIDEP enhancement factor in 1,4-dioxane was determined to be −30 × P
eq, where P
eq is the spin polarization of nitroxide at thermal equilibrium. Net emissive CIDEP was also observed by FT-EPR measurements
on the nitroxide quenching of the triplet excited state of tryptophan residue in α-lactalbumin. Magnitude of CIDEP created
in α-lactalbumin/nitroxide system depends on the pH condition of α-lactalbumin solution, which is related to protein folding
dynamics. We argue the CIDEP mechanism at the α-lactalbumin surface and propose a possibility of a novel CIDEP method to probe
a protein surface and structural changes. 相似文献
987.
The phase transition mechanism in squaric acid is reviewed from the viewpoint of the pressure dependence of the O—H—O bond length (2R). The two-dimensional pressure effect on Tc is extracted from the hydrostatic pressure behaviour by taking account of the uniaxial stress applied perpendicular to the layer planes. The result shows that if 2R(H2SQ) is stretched to 2R(D2SQ) the phase transition temperature 7H c of H2SQ coincides with TD c of D2SQ. This result supports the suggestion that the phase transition mechanism is of the order-disorder type. 相似文献
988.
Chen JH Wang MZ Adachi I Aihara H Arinstein K Aulchenko V Aushev T Bakich AM Balagura V Barberio E Bay A Bedny I Belous K Bitenc U Bondar A Bozek A Bracko M Browder TE Chang MC Chao Y Chen A Chen KF Chen WT Cheon BG Chistov R Cho IS Choi SK Choi Y Dalseno J Dash M Drutskoy A Eidelman S Golob B Ha H Haba J Hara T Hayasaka K Hayashii H Hazumi M Heffernan D Hoshi Y Hou WS Hsiung YB Hyun HJ Inami K Ishikawa A Ishino H Itoh R Iwasaki M Joshi NJ Kah DH Kaji H Kapusta P Katayama N Kawasaki T Kichimi H 《Physical review letters》2008,100(25):251801
Using a 492 fb{-1} data sample collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e{+}e{-} collider, we observe the decay B{0}-->ppK*0 with a branching fraction of (1.18{-0.25}{+0.29}(stat)+/-0.11(syst))x10{-6}. We study the decay dynamics of B{0}-->ppK*0 and compare with B{+}-->ppK*+. The K*0 meson is found to be almost 100% polarized (with a fraction of (101+/-13+/-3)% in the helicity zero state), while the K*+ meson has a (32+/-17+/-9)% fraction in the helicity zero state. The direct CP asymmetries for B{0}-->ppK*0 and B{+}-->ppK*+ are measured to be -0.08+/-0.20+/-0.02 and -0.01+/-0.19+/-0.02, respectively. In addition, we report improved measurements of the branching fractions B(B{+}-->ppK*+)=(3.38{-0.60}{+0.73}+/-0.39)x10{-6} and B(B{0}-->ppK{0})=(2.51{-0.29}{+0.35}+/-0.21)x10{-6}, which supersede our previous measurements. 相似文献
989.
M. Mihara K. Matsuta D. Nishimura T. Nagatomo R. Matsumiya S. Momota T. Ohtsubo T. Izumikawa D. M. Zhou Y. N. Zheng M. Ogura H. Akai J. Komurasaki M. Fukuda D. Ishikawa Y. Nojiri H. Hirano S. Takahashi R. Watanabe T. Kubo S. Y. Zhu A. Kitagawa M. Kanazawa S. Sato M. Torikoshi T. Sumikama T. Minamisono J. R. Alonso G. F. Krebs T. J. M. Symons 《Hyperfine Interactions》2007,178(1-3):83-86
The spin-lattice relaxation times T 1 for short-lived β emitters 25Al(I?=?5/2, T 1/2?= 7.2 s) and 28P(I?=?3, T 1/2?= 270 ms) in Pt were measured by means of the β-NMR technique. As a result, T 1[25Al in Pt] = (1.1 $^{+\ 0.7}_{-\ 0.3})$ s and T 1[28P in Pt] >0.5 s were obtained at temperatures of 17 and 20 K, respectively. The Knight shifts were estimated from the Korringa relation, which were evaluated by comparing to the first principle calculations. 相似文献
990.
Abstract Exchange of hydrogen isotopes between diffusing and trapped populations was found with successive injections of 25 keV D2 + and 100 or 140 keV H2 + into Al surface by simultaneously detecting elastically recoilled hydrogen and deuterium using 2 MeV He+. When backward diffusion of injected hydrogen toward surface was supposed to be impeded or by-passed by structural changes in the subsurface layer due to ion bombardment, effective replacement cross-section of about 1.4 × 10?18 cm2 was observed. Otherwise, namely when the hydrogen backward diffusion is supposed to be rather free, the effective cross section of about 7.8 × 10?18 was observed. Due to the difference in energy of the first and second injections, this phenomenon is different from that so called “isotopic exchange”, which occurs through collisional process. 相似文献