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51.
Electrofiltration of hydrosols in fixed-bed filters was studied experimentally. The experimental variables examined included media type, electric field strength, and suspension pH values. The extent of particle removal was found to improve with the application of the electric field, and lower pH values favor particle collection. The filtrate quality displayed the transient behavior of increasing particle concentration with time. A simple model which assumes that the filter coefficient decreases linearly with the extent of deposition was developed and found capable of predicting the observed behavior. Copyright 2000 Academic Press. 相似文献
52.
53.
Electronic Moirè patterns found on lead (Pb) quantum islands can serve as a template to grow self-organized cluster (nanopucks) arrays of various materials. These patterns can be divided into fcc- and hcp-stacked areas, which exhibit different binding strengths to the deposited adatoms. For Ag adatoms, the binding energy can differ substantially and the confined nucleation thus occurs in the fcc sites. Both the size distribution and spatial arrangement of the Ag nanopucks are analyzed and found to be commensurate with the characteristics of the template island, which exhibits a bilayer oscillatory behavior. 相似文献
54.
Taking the view that computation is after all physical, we argue that physics, particularly quantum physics, could help extend
the notion of computability. Here, we list the important and unique features of quantum mechanics and then outline a quantum
mechanical “algorithm” for one of the insoluble problems of mathematics, the Hilbert's tenth and equivalently the Turing halting
problem. The key element of this algorithm is the computability and measurability of both the values of physical observables and of the quantum-mechanical probability distributions for these values. 相似文献
55.
By employing the technique of asynchronous mode locking, we have successfully demonstrated direct generation of stable 10 GHz 816 fs pulse trains with a supermode-suppression ratio >70 dB from a hybrid mode-locked Er-fiber laser. When the modulation frequency deviates from the cavity harmonic frequency by 15-40 kHz, stable femtosecond soliton pulses are formed. Our results demonstrate that asynchronous mode locking can act as an effective mechanism for achieving a shorter pulse width and for stabilizing high-repetition-rate pulse trains in soliton fiber lasers. 相似文献
56.
Chin CL Wehrli FW Hwang SN Jaggard DL Hackney DB Wehrli SW 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,160(1):20-25
It is well known that one-dimensional (1D) q-space imaging allows retrieval of structural information at cellular resolution. Here we demonstrate by simulation that boundary morphology of structured materials can be derived from 2D q-space mapping. Based on a finite-difference model for restricted diffusion, 2D q-space maps obtained from water diffusion inside apertures at various levels of asperity were simulated. The results indicate that the observed ring patterns (diffraction minima) reveal the boundary profiles of the apertures but become blurred in the case of significant variation in aperture size. For uniform size distribution of apertures, a quantitative measure of surface roughness can be established by means of spatial autocorrelation analysis. The results suggest that 2D q-space imaging may allow probing of the boundary morphology of structured materials and possibly biological cells. 相似文献
57.
E. V. Charnaya Cheng Tien N. V. Chejina M. K. Lee S. Y. Sun 《Physics of the Solid State》2007,49(3):449-453
27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) was studied for diluted alkali earth metal-doped lanthanum
manganite solid solutions in the lanthanum aluminate (1 − y)LaAlO3-yLa0.67
A
0.33MnO3 (A = Ca, Sr, Ba) with y =0, 2, 3, and 5 mol %. The spectra depended on the dopant species and showed higher substitutional ordering for the Ba-containing
mixed crystals. Magnetically shifted lines were observed in all solid solutions and were attributed to Al in the octahedral
oxygen environment near manganese trivalent ions. Nonlinear dependences of their intensity were referred to the manganese-rich
cluster formation. An additional MAS NMR line corresponding to aluminum at sites different from the octahedral site in pure
LaAlO3 was observed only in solutions doped with Ba. 3Q MAS NMR revealed that the broadening of this line is governed mainly by quadrupole coupling and made it possible to calculate
the isotropic chemical shift.
The article was submitted by the authors in English. 相似文献
58.
An experimental and computational investigation into the autoignition of methanol under high‐pressure and low‐to‐intermediate temperature conditions is conducted. The ignition delay results have been obtained using a heated rapid compression machine, over a pressure range of 7–30 bar, a temperature range of 850–1100 K, and an equivalence ratio range of 0.25–2.0. Using kinetic schemes recently reported in the literature for the combustion of methanol, the experimental results are compared to computationally obtained values. The kinetic schemes studied are found to significantly underpredict ignition delays for the conditions investigated. A sensitivity analysis of the computed results to reaction rate constants is also conducted. It is shown that the reaction of methanol with HO2 radical is critical to the predicted values of ignition delays under the current experimental conditions. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 175–184, 2011 相似文献
59.
60.
Harihara Padhy Duryodhan Sahu Dhananjaya Patra Murali Krishna Pola Jen‐Hsien Huang Chih‐Wei Chu Kung‐Hwa Wei Hong‐Cheu Lin 《Journal of polymer science. Part A, Polymer chemistry》2011,49(15):3417-3425
Two β‐cyano‐thiophenevinylene‐based polymers containing cyclopentadithiophene ( CPDT‐CN ) and dithienosilole ( DTS‐CN ) units were synthesized via Stille coupling reaction with Pd(PPh3)4 as a catalyst. The effects of the bridged atoms (C and Si) and cyano‐vinylene groups on their thermal, optical, electrochemical, charge transporting, and photovoltaic properties were investigated. Both polymers possessed the highest occupied molecular orbital (HOMO) levels of about ?5.30 eV and the lowest unoccupied molecular orbital (LUMO) levels of about ?3.60 eV, and covered broad absorption ranges with narrow optical band gaps (ca. 1.6 eV). The bulk heterojunction polymer solar cell (PSC) devices containing an active layer of electron‐donor polymers ( CPDT‐CN and DTS‐CN ) blended with an electron‐acceptor, that is, [6,6]‐phenyl‐C61‐butyric acid methyl ester (PC61BM) or [6,6]‐phenyl‐C71‐butyric acid methyl ester (PC71BM), in different weight ratios were explored under 100 mW/cm2 of AM 1.5 white‐light illumination. The PSC device based on DTS‐CN: PC71BM (1:2 w/w) exhibited a best power conversion efficiency (PCE) value of 2.25% with Voc = 0.74 V, Jsc = 8.39 mA/cm2, and FF = 0.36. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011. 相似文献