Silver-doped calcium phosphate nanopowders were successfully prepared by the cost-effective electrostatic spray-pyrolysis
process. The properties of the silver-doped nanopowder annealed at 500°C for 30 min were investigated through X-ray diffraction
analysis, field emission scanning electron microscope, and Fourier transform infrared spectroscopy. The silver-doped nanopowders
with 70–90 nm particle size showed an antibacterial performance against Escherichia coli. 相似文献
Applying the theory of generalized functions we obtain the Shannon sampling theorem for entire functions F(z) of exponential growth and give its error estimate which shows how much the error depends on the sampling size and bandwidth for given domain of the signal F(z). As an application we obtain a uniqueness theorem for entire functions and temperature functions. 相似文献
Examples of Kähler metrics of constant scalar curvature are relatively scarce. Over the past two decades, several workers in geometry and physics have used symmetry reduction to construct complete Kähler metrics of constant scalar curvature by ODE methods. One fruitful idea--the ``Calabi ansatz'--is to begin with an Hermitian line bundle over a Kähler manifold, and to search for Kähler forms in some disk subbundle, where is the logarithm of the norm function and is a function of one variable.
Our main technical result (Theorem A) is the calculation of the scalar curvature for an arbitrary Kähler metric arising from the Calabi ansatz. This suggests geometric hypotheses (which we call ``-constancy') to impose upon the base metric and Hermitian structure in order that the scalar curvature of be specified by solving an ODE. We show that -constancy is ``necessary and sufficient for the Calabi ansatz to work' in the following sense. Under the assumption of -constancy, the disk bundle admits a one-parameter family of complete Kähler metrics of constant scalar curvature that restrict to on the zero section (Theorems B and D); an analogous result holds for the punctured disk bundle (Theorem C). A simple criterion determines when such a metric is Einstein. Conversely, in the absence of -constancy the Calabi ansatz yields at most one metric of constant scalar curvature, in either the disk bundle or the punctured disk bundle (Theorem E).
Many of the metrics constructed here seem to be new, including a complete, negative Einstein-Kähler metric on the disk subbundle of a stable vector bundle over a Riemann surface of genus at least two, and a complete, scalar-flat Kähler metric on .
Geocenter motion (GCM) is one important topic for constructing and maintaining the terrestrial reference frame and its applications.
GCM is studied from CHAMP with the multi-step approach in this paper. Geometric orbits of CHAMP in 2001–2006 are precisely
determined with the kinematic method only from the satellite-borne GPS zero-difference data. Then a GCM time series is estimated
from the precise kinematic orbits based on the theory of satellite dynamics to fit the CHAMP’s real geometric orbits. We compare
the series with the geocenter series used in ITRF2005. Then the GCM series are analyzed with Fourier transform and wavelet
transformation. The mean motions within 6 years in TX, TY and TZ directions are respectively 0.8 mm, 2.2 mm, and 7.9 mm. The trends of GCM in the three directions are 0.495 mm/a, −0.004
mm/a, and 1.309 mm/a, respectively. The long-term movement (2001–2006) indicates that the crustal figure is changing. The
seasonal variations are the main component which may be excitated by the mass redistribution of Earth’s fluid layer, e.g.
ocean, atmosphere and continental water. The inter-annual variations are also found in the GCM series measured with CHAMP.
Supported by the International S&T Cooperation Program of China (Grant No. 2006DFA21980), the National Hi-tech R&D Program
of China (Grant No. 2006AA12z303), the National Natural Science Foundation of China (Grant No. 40774009), and the Natural
Science Foundation of Shandong Province, China (Grant No. Y2003E01) 相似文献
In this paper, we provide an easily satisfied relaxation condition for the primaldual interior path-following algorithm to solve linear programming problems. It is shown that the relaxed algorithm preserves the property of polynomial-time convergence. The computational results obtained by implementing two versions of the relaxed algorithm with slight modifications clearly demonstrate the potential in reducing computational efforts.Partially supported by the North Carolina Supercomputing Center, the 1993 Cray Research Award, and a National Science Council Research Grant of the Republic of China. 相似文献
The concept of partitionable starters is introduced and it is shown how to construct: a balanced Howell rotation on mn players from a balanced Howell rotation on n players, a balanced Howell rotation on m players, and a partitionable starter on m players. Two results concerning the existence of partitionable starters are proved 相似文献
We describe a soliton bag model which incorporates explicitly SU(2) × SU(2) chiral dynamics, including the conservation of the polar vector current, the partial conservation of the axial vector current, and the SU(2) × SU(2) current algebra. This model appears to be renormalizable so that higher order effects may be treated systematically. 相似文献
Ground-state hyperfine splittings in hydrogen and muonium are very well measured. Their difference, after correcting for magnetic moment and reduced mass effects, is due solely to proton structure-the large QED contributions for a pointlike nucleus essentially cancel. The rescaled hyperfine difference depends on the Zemach radius, a fundamental measure of the proton, computed as an integral over a product of electric and magnetic proton form factors. The determination of the Zemach radius, (1.019+/-0.016) fm, from atomic physics tightly constrains fits to accelerator measurements of proton form factors. Conversely, we can use muonium data to extract an experimental value for QED corrections to hydrogenic hyperfine data. There is a significant discrepancy between measurement and theory, in the same direction as a corresponding discrepancy in positronium. 相似文献
We demonstrate that meandering as well as regular spiral waves can form in a well-controlled culture layer of rat ventricle cells and that the meandering spiral wave, in particular, can generate an alternant rhythm. These observations are made possible by a newly developed, noninvasive phase contrast macro-optics that is simple but highly effective in visualizing the contractile motion of the populations of cardiac cells. 相似文献
We develop a lattice mean field theory for ferromagnetic ordering in diluted magnetic semiconductors by taking into account the spatial fluctuations associated with random disorder in the magnetic impurity locations and the finite mean free path associated with low carrier mobilities. Assuming a carrier-mediated indirect RKKY exchange interaction among the magnetic impurities, we find substantial deviation from the extensively used continuum Zener model Weiss mean field predictions. Our theory allows accurate analytic predictions for Tc and provides simple explanations for a number of observed anomalies, including the non-Brillouin function magnetization curves, the suppressed low-temperature magnetization saturation, and the dependence of Tc on conductivity. 相似文献