973 resultados para B ... n C ... f.


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Three enclosures (10 x 10 x 1.5-1.3 m in depth) were set beside Dianch Lake, Kunming, People's Republic of China, for the period from July 28 to August 26, 2002. The enclosures were filled with cyanobacterial (Microcystis aeruginosa) water bloom-containing lake water. Lake sediment that contained macrophytes and water chestnut seeds was spread over the entire bottom of each enclosure. Initially, 10 g/m(2) of lysine was sprayed in Enclosure B, and 10 g/m(2) each of lysine and malonic acid were sprayed together in Enclosure C. Enclosure A remained untreated and was used as a control. The concentrations of lysine, malonic acid, chlorophyll a, and microcystin as well as the cell numbers of phytoplankton such as cyanobacteria, diatom, and euglena were monitored. On day 1 of the treatment, formation of cyanobacterial blooms almost ceased in Enclosures B and C, although Microcystis cells in the control still formed blooms. On day 7 Microcystis cells in Enclosure B that had been treated with lysine started growing again, whereas growth was not observed in Microcystis cells in Enclosure C, which had been treated with lysine and malonic acid. On day 28 the surface of Enclosure B was covered with water chestnut (Trapa spp.) and the Microcystis blooms again increased. In contrast, growth of macrophytes (Myriophllum spicatum and Potamogeton crispus) was observed in Enclosure C; however, no cyanobacterial blooms were observed. Lysine and malonic acid had completely decomposed. The microcystin concentration on day 28 decreased to 25% of the initial value, and the pH shifted from the initial value of 9.2 to 7.8. We concluded that combined treatment with lysine and malonic acid selectively controlled toxic Microcystis water blooms and induced the growth of macrophytes. (c) 2005 Wiley Periodicals, Inc.

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Hybrid bulk heterojunction solar cells based on blend of poly(3-hexylthiophene) (P3HT) and TiO2 nanotubes or dye(N719) modified TiO2 nanotubes were processed from solution and characterized to research the nature of organic/inorganic hybrid materials. Compared with the pristine polymer P3HT and TiO2 nanoparticles/P3HT solar cells, the TiO2 nanotubes/P3HT hybrid solar cells show obvious performance improvement, due to the formation of the bulk heterojunction and charge transport improvement. A further improvement in the device performance can be achieved by modifying TiO2 nanotube surface with a standard dye N719 which can play a role in the improvement of both the light absorption and charge dissociation. Compared with the non-modified TiO2 nanotubes solar cells, the modified ones have better power conversion efficiency under 100 mW/cm(2) illumination with 500W Xenon lamp. (C) 2008 Elsevier B. V. All rights reserved.

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A detailed analysis of the photoluminescence (PL) from Si nanocrystals (NCs) embedded in a silicon-rich SiO2 matrix is reported. The PL spectra consist of three Gaussian bands (peaks A,B, and C), originated from the quantum confinement effect of Si NCs, the interface state effect between a Si NC and a SiO2 matrix, and the localized state transitions of amorphous Si clusters, respectively. The size and the surface chemistry of Si NCs are two major factors affecting the transition of the dominant PL origin from the quantum confinement effect to the interface state recombination. The larger the size of Si NCs and the higher the interface state density (in particular, Si = O bonds), the more beneficial for the interface state recombination process to surpass the quantum confinement process, in good agreement with Qin's prediction in Qin and Li [Phys. Rev. B 68, 85309 (2003)]. The realistic model of Si NCs embedded in a SiO2 matrix provides a firm theoretical support to explain the transition trend.

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Three different inorganic-organic hetero-junctions (A : ITO/SiO2/Alq(3)/Al, B: ITO/Alq3/SiO2/Al and C: ITO/SiO2/Alq(3)/ SiO2/Al) were fabricated. The emission can be observed only under positive bias in devices A and B, but under both biases in device C according to their brightness waveforms. With increasing voltage, the increase in blue emission in devices B and C is faster than that in green emission. This is because that the recombination of hot electrons and holes, i.e., electron-hole pairs, produced blue emission in devices B and C, and the recombination of electrons injected from Al with the accumulated holes, which are excited by hot electrons, produced green emission in device A. Hence, the emissions of the devices are attributed to not only the recombination of electrons and accumulated holes, but also the cathodoluminescence-like (CL-like) emission.

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We investigate the quantum dynamics of the quantum-dot cellular automata qubit in the presence of a quantum point contact detector by modified rate equations. It is demonstrated that the qubit information can be resolved by measuring the detector current variation. Furthermore, we show that this oscillating current and the electron occupation probabilities in states \b> and \c> decay drastically as the dephasing rate increases, clearly revealing the influence of the dephasing induced by the detector. Moreover, it is shown that the operation speed of the quantum-dot cellular automata qubit may be adjusted by varying the interdot coupling strength. (C) 2003 American Institute of Physics.

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A systematic investigation of crystallographic and intrinsic magnetic properties of the hydrides R3Fe29 - xVxHy (R = Y, Ce, Nd, Sm, Gd, Tb, and Dy) has been performed in this work. The lattice constants a, b, and c and the unit cell volume of R3Fe29 - xVxHy decrease with increasing rare-earth atomic number from Nd to Dy, except for Ce, reflecting the lanthanide contraction. Hydrogenation results in regular anisotropic expansions along the a-, b-, and c-axes in this series of hydrides. Abnormal crystallographic and magnetic properties of Ce3Fe27.5V1.5H6.5, like Ce3Fe27.5V1.5, suggest that the Ce ion is non-triply ionized. Hydrogenation leads to the increase in both Curie temperature for all the compounds and in the saturation magnetization at 4.2 K and RT for R3Fe29 - xVx with R = Y, Ce, Nd, Sm, Gd, and Dy, except for Tb. Hydrogenation also leads to a decrease in the anisotropy field at 4.2 K and RT for R3Fe29 - xVx with R = Y, Ce, Nd, Gd, Tb, and Dy, except for Sm. The Ce3Fe27.5V1.5 and Gd3Fe28.4V0.6 show the larger storage of hydrogen with y = 6.5 and 6.9 in these hydrides. (C) 1998 Elsevier Science B.V. All rights reserved.

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Fourier transform photoluminescence measurements were carried out to investigate the optical transitions in InxGa1-xAs/InyAl1-yAs one-side-modulation-doped asymmetric step quantum wells. Samples with electron density n(s) between 0.8 and 5.3 x 10(12) cm(-2) rue studied. Strong recombination involving one to three populated electron subbands with the first heavy-hole subband is observed. Fermi edge singularity (FES) clearly can be observed for some samples. The electron subband energies in the InGaAs/InAlAs step quantum wells were calculated by a self-consistent method, taking into account strain and nonparabolicity effects and the comparison with the experimental data shows a good agreement. Our results can help improve understanding for the application of InGaAs/InAlAs step quantum wells in microelectronic and optoelectronic devices. (C) 1998 Elsevier Science Ltd. All rights reserved.

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High-quality InGaAs/InAlAs/InP high-electron-mobility transistor (HEMT) structures with lattice-matched or pseudomorphic channels have been grown by molecular-beam epitaxy (MBE). The purpose of this work is to enhance the channel conductivity by changing the epitaxial structure and growth process. With the use of pseudomorphic step quantum-well channel, the highest channel conductivity is achieved at x = 0.7, the corresponding electron mobilities are as high as 12300 (300 K) and 61000 cm(2)/V.s (77 K) with two-dimensional electron gas (2DEG) density of 3.3 x 10(12) cm(-2). These structures are comprehensively characterized by Hall measurements, photoluminescence, double crystal X-ray diffraction and transmission electron microscopy. Strong room-temperature luminescence is observed, demonstrating the high optical quality of the samples. We also show that decreasing the In composition in the InyAl1-yAs spacer is very effective to increase the 2DEG density of PHEMT structures. (C) 1998 Published by Elsevier Science B.V. All rights reserved.

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:(1).PHC/N.(2)BACC/NBC/N...

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The near-threshold highly bound states of all three stable isotopic variants of molecular hydrogen have been studied. Numerous perturbations and unexpected transitions are observed as far as 1cm(-1) just below the second dissociation threshold. This complex structure may arise from a combination of nonadiabatic coupling between B, B', C electronic states, perturbations due to. ne and hyperfine interactions, and strong shape resonances. The perturbed near-threshold states and vibrational continuum exhibit finegrained structure, differing greatly between isotopes because of varying nonadiabatic coupling.

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,,,(0.00.51.05.010.0ga.i.·kg-1),(),;;U=A/(1+B×C);0.322.8811.43ga.i.·kg-1;,18.61%8.36%,;

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沿""""Monte Carlo广Monte CarloBCBCBA/BCB80BBBO80%BA/BCBBA/BCABBBABCABCABMonte Car toBBABABAABABACBCABCABCBCACABAA/CCABAC'

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NiZrTi-VCrCrTiTi017Zr008V035Cr010Ni030BFeCoAlXRDICPSEMEDXXPSEIS线TiVCrTiVCrNiCrTi0.25-xZr_xV0.35Cr0.1Ni0.3x005-015bccc14LavesZr005008x008015xx00801550Tio17zr"sVscrol0Ni03303K313K9070275mAgTi17Zr008VSCr0Ni03050kJmolNlnBFeCAITio17zroosvo35Crol0Nio3Tio17Zr008Vo35Cro10Ni020Mnol390n1Ag253343KTiol7Zr08V035Cr0JONioz5Mnoos167298mAgZrVTiVCr

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Armco~-PH~-PH(a) 线Tafep(b)RpCI_cI_(2c)I_(3c)I_(4c)ΔE2E3ΔEEa = I_(2c)/I_c, b = I_(3c)/I_c, c = I_(4c)/I_(2c), (4b-3a~2)~(1/2)(3c-2b)~(1/2)(2c-a~2)~(1/2)S_jI_(corr) = I_c/S_j b_c = ΔE/lg((a+s_j)/2) b_a = -E/lg((a-s_j)/2)ΔEI_λSI_(corr) = from i=1 to n I/ from i=1 ton S_ b_c = form to n ΔE_/ form i=1 to n lg ((a_λ+S_)/2) b_a = form i=1 ton ΔE_/ form i=1 to n lg ((a_λ-S_)/2)LaplaceE_1(t) = λ_o(R_s+R_p) - 2_oR_p (e~(-)/RpC))/(1+e~(/RpC)) (o<<) E_2(t) = _o(R_s+R_p) + 2λ_oR_p (e~(-(-)/RpC))/(1+e~(λ/RpC)) <2)Eλ:ΔE = _oR_p (e~/RpC)-1)/(e~/RpC)+1) = 2λ_oR_p t_(anh)/(2RpC)) Δh = _o RsEhRp =E)/(2_o) >>RpC (_o)/(ΔE) = C/λ + 1/(2Rp) λ<pCR_pCR_s使R_p线λ_a = k_a [OH~-][ψ~-]~(0.5)e~(3/2Fψ/RT) λ_c = k_c [H~+] e~(/2RT) [((partial deriv) ψ_(corr))/((partial deriv) PH)]_([~-]) = -55 [((partial deriv) ψ_(corr))/((partial deriv) lg[~-])]_(PH) = -15 [((partial deriv) lg I_(corr))/((partial deriv) PH)]_([~-]) = -0.4 [((partial deriv) lg I_(corr))/((partial deriv) lg~-])]_(PH) = 0.13 α_(corr)/α lg[] = -44 α lg I_(corr)/α lg[] = 0.45 b_a = 40 b_c = 120 TafelTafelPHψ~-PHψ~-

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ab721cIII