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排序方式: 共有243条查询结果,搜索用时 15 毫秒
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94.
Tamara A. Leskova Ingve Simonsen Alexei A. Maradudin 《Waves in Random and Complex Media》2002,12(3):307-319
We study the statistical properties of the scattering matrix S(q|k) for the problem of the scattering of light of frequency ω from a randomly rough one-dimensional surface, defined by the equation x3=ζ(x1), where the surface profile function ζ(x1) constitutes a zero-mean, stationary, Gaussian random process. This is done by studying the effects of S(q|k) on the angular intensity correlation function C(q,k|q',k')=〈I(q|k)I(q'|k')〉-〈I(q|k)〉〈I(q'|k')〉, where the intensity I(q|k) is defined in terms of S(q|k) by I(q|k)=L-11(ω/c)|S(q|k)|2, with L1 the length of the x1 axis covered by the random surface. We focus our attention on the C(1) and C(10) correlation functions, which are the contributions to C(q,k|q',k') proportional to δ(q-k-q'+k') and δ(q-k+q'-k'), respectively. The existence of both of these correlation functions is consistent with the amplitude of the scattered field obeying complex Gaussian statistics in the limit of a long surface and in the presence of weak surface roughness. We show that the deviation of the statistics of the scattering matrix from complex circular Gaussian statistics and the C(10) correlation function are determined by exactly the same statistical moment of S(q|k). As the random surface becomes rougher, the amplitude of the scattered field no longer obeys complex Gaussian statistics but obeys complex circular Gaussian statistics instead. In this case the C(10) correlation function should therefore vanish. This result is confirmed by numerical simulation calculations. 相似文献
95.
The earlier structure proposal for carolic acid as (E,R)-5-methyl-3-(2'-tetrahydrofurylidene)tetrahydro-furan-2,4-dione has been confirmed using diffractometercollected X-ray data. The extended bond delocalization makes the cis isomerization of carolic acid understandable. 相似文献
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97.
Immobilization of DNA (encoding) on solid nanoparticles requires surface chemistry, which is well established for gold surfaces but often tedious and not generally applicable for many other inorganic surface materials. While substantial effort has been devoted to expanding surface chemistry techniques for solid nanoparticles, considerably less attention has been given to the development of noncovalent attachment of DNA to soft nanoparticles, like liposomes. Here we report a DNA-controlled assembly of liposomes in solution and on solid supported membranes, this process displays remarkably sharp thermal transitions from an assembled to a disassembled state, allowing application of DNA-controlled liposome assembly for the detection of polynucleotides (e.g., DNA) with single mismatch discrimination power. The method is based on a single DNA strand (contains two lipid membrane anchors), which is able to noncovalently attach to a liposome surface. This design enables detection of biological polynucleotide targets as the complementary strand can be unmodified DNA and RNA strands. 相似文献
98.
Thormann E Simonsen AC Hansen PL Mouritsen OG 《Langmuir : the ACS journal of surfaces and colloids》2008,24(14):7278-7284
The interaction between a colloidal polystyrene particle mounted on an AFM cantilever and a hydrophilic and a hydrophobic surface in aqueous solution is investigated. Despite the apparent simplicity of these two types of systems a variety of different types of interactions are observed. The system containing the polystyrene particle and a hydrophilic surface shows DLVO-like interactions characteristic of forces between charged surfaces. However, when the surface is hydrophobized the interaction changes dramatically and shows evidence of a bridging air bubble being formed between the particle and the surface. For both sets of systems, plateaus of constant force in the force curves are obtained when the particle is retracted from the surface after being in contact. These events are interpreted as a number of individual polystyrene molecules that are bridging the polystyrene particle and the surface. The plateaus of constant force are expected for pulling a hydrophobic polymer in a bad (hydrophilic) solvent. The plateau heights are found to be of uniform spacing and independent of the type of surface, which suggests a model by which collapsed polymers are extended into the aqueous medium. This model is supported by a full stretching curve showing also the backbone elasticity and a stretching curve obtained in pentanol, where the plateau changes to a nonlinear force response, which is typical for a polymer in a good or neutral solvent. We suggest that these polymer bridges are important in particular for the interaction between polystyrene and the hydrophilic surface, where they to some extent counteract the long-range electrostatic repulsion. 相似文献
99.
Vibe L. E. Simonsen Linda Nørskov Kent Kammer Hansen 《Journal of Solid State Electrochemistry》2008,12(12):1573-1577
A series of La2 − x
Sr
x
CuO4 (x = 0.0, 0.05, 0.15, 0.25 and 0.35) compounds was investigated for the use of direct electrochemical reduction of NO in an
all-solid-state electrochemical cell. The materials were investigated using cyclic voltammetry in 1% NO in Ar and 10% O2 in Ar. The most selective electrode material was La2CuO4, which had an activity of NO reduction that was 6.8 times higher than that of O2 at 400 °C. With increasing temperature, activity increased while selectivity decreased. Additionally, conductivity measurements
were carried out, and the materials show metallic conductivity behavior which follows an adiabatic small polaron hopping mechanism. 相似文献
100.
Aleksander S. Simonsen Sigurd Askeland Morten Førre 《Central European Journal of Physics》2013,11(9):1099-1106
In this paper, we present theoretical results for the process of non-sequential two-photon double ionization of helium at the photon energy 42 eV. Our approach is based on solving the time-dependent Schrödinger equation in a B-spline based numerical framework. Information about the process is obtained by extracting the double-ionized component by means of uncorrelated final states. The total (generalized) cross section for the process is extracted, as well as differential cross sections resolved in electron energies and ejection angles. We focus on the impact the final-state correlation has on the accuracy of the cross sections. 相似文献