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981.
We present a test of the local Lorentz invariance of post-Newtonian gravity by monitoring Earth's gravity with a Mach-Zehnder atom interferometer that features a resolution of up to 8 x 10{-9}g/sqrt[Hz], the highest reported thus far. Expressed within the standard model extension (SME) or Nordtvedt's anisotropic universe model, the analysis limits four coefficients describing anisotropic gravity at the ppb level and three others, for the first time, at the 10 ppm level. Using the SME we explicitly demonstrate how the experiment actually compares the isotropy of gravity and electromagnetism. 相似文献
982.
Nilius N Ganduglia-Pirovano MV Brázdová V Kulawik M Sauer J Freund HJ 《Physical review letters》2008,100(9):096802
Low-temperature STM measurements combined with density functional theory calculations are employed to study the adsorption of gold on alumina/NiAl(110). The binding of Au monomers involves breaking of an oxide Al-O bond below the adatom and stabilizing the hence undercoordinated O ion by forming a new bond to an Al atom in the NiAl. The adsorption implies negative charging of the adatom. The linear arrangement of favorable binding sites induces the self-organization of Au atoms into chains. For every ad-chain, the number of transfer electrons from the support is determined by analyzing the node structure of the corresponding highest occupied molecular orbital. 相似文献
983.
Sven Mahnkopf Duane A. Louderback Dhiraj Kumar Peter S. Guilfoyle 《Optical and Quantum Electronics》2008,40(14-15):1205-1209
The effect of the mode order of a vertical cavity surface emitting laser on the surface normal coupling efficiency into a horizontal optical waveguide is discussed. The numerical results are compared with experimental observations. 相似文献
984.
The problem of nonconservation of the electromagnetic current for two-boson systems on the light front obtained by truncation of the quasi-potential expansion is studied. We found that current conservation can be restored by a subtle choice of the truncation of the expansion of the current operator, while the naive truncation of the expansion of both current and effective interaction violates covariance and current conservation. The framework allows to treat at the same level the current operator for bound and scattering states. The generalization to two-fermion systems is briefly discussed. 相似文献
985.
986.
Summary: The sol–gel transition of a radical chain cross‐linking copolymerization system [N‐vinylcaprolactam/2‐hydroxylethyl methacrylate/allyl methacrylate] has been studied using in situ time‐resolved dynamic light scattering (DLS) and in situ rheology. A critical dynamic behavior was observed near the sol–gel transition, which was characterized by the presence of a power‐law spectra over three decades in the time–intensity correlation function g2(t) − 1 ∼ t−μ and over two decades in the oscillatory shear experiment G′(ω) ∼ G″(ω) ∼ ωn. A comparison of the obtained critical exponents μ ≈ 0.62 and n ≈ 0.75 was made. The theory predicts a relationship between these exponents, but up to now no experimental comparison has been done. The experimental results favor the percolation model, with a fractal dimension df of the gel clusters of 1.67.
987.
Sven Richter Volodymyr Boyko Rolf Matzker Klaus Schrter 《Macromolecular rapid communications》2004,25(16):1504-1509
Summary: The sol–gel transition of two thermoreversible gelling mixtures made of xanthan gum and locust‐bean gum has been studied by using in situ, time‐resolved dynamic light scattering (DLS) and in situ rheology. A critical dynamical behavior was observed near the sol–gel transition, which was characterized by the presence of power‐law spectra over three and four decades in the time‐intensity correlation function g2(t) − 1 ∼ t−μ and over four and three decades in the oscillatory shear experiment G′(ω) ∼ G″(ω) ∼ ωn. A comparison of the critical exponents obtained (μ1 ≈ 0.36, μ2 ≈ 0.32 and n1 ≈ 0.62, n2 ≈ 0.67) was made as a function of the dependence of the two mixing ratios according to the theory by Doi and Onuki. New experiments were also performed to compare the critical exponents on such a thermoreversible system.
988.
989.
In complex foods, bioactive secondary plant metabolites (SPM) can bind to food proteins. Especially when being covalently bound, such modifications can alter the structure and, thus, the functional and biological properties of the proteins. Additionally, the bioactivity of the SPM can be affected as well. Consequently, knowledge of the influence of chemical modifications on these properties is particularly important for food processing, food safety, and nutritional physiology. As a model, the molecular structure of conjugates between the bioactive metabolite benzyl isothiocyanate (BITC, a hydrolysis product of the glucosinolate glucotropaeolin) and the whey protein α-lactalbumin (α-LA) was investigated using circular dichroism spectroscopy, anilino-1-naphthalenesulfonic acid fluorescence, and dynamic light scattering. Free amino groups were determined before and after the BITC conjugation. Finally, mass spectrometric analysis of the BITC-α-LA protein hydrolysates was performed. As a result of the chemical modifications, a change in the secondary structure of α-LA and an increase in surface hydrophobicity and hydrodynamic radii were documented. BITC modification at the ε-amino group of certain lysine side chains inhibited tryptic hydrolysis. Furthermore, two BITC-modified amino acids were identified, located at two lysine side chains (K32 and K113) in the amino acid sequence of α-LA. 相似文献
990.