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51.
In this paper, gold nanoparticles coated with palladium dots (Pd@Au) bimetallic nanostructures have been reported to have a peroxidase like activity which is not found in their monometallic counterparts. Based on this finding, we have developed an immunoassay in which antibody-modified Pd@Au nanostructure catalyzes the dimerization of a fluorogenic substrate for peroxidase, 3-(4-dihydroxy phenyl) propionic acid (HPPA), to generate high fluorescence signal. Specific antibodies against bensulfuron-methyl were generated by using a well characterized bensulfuron–protein conjugate as an immunogen, and the assay was performed in a competitive immunoassay format where Pd@Au nanostructure was bound to secondary antibody to show the peroxidase like activity. The developed immunoassay exhibited an excellent sensitivity showing a dynamic response range from 0.001 to 100 ng mL−1 for herbicide bensulfuron-methyl with a detection limit of 0.01 ng mL−1 (n = 3). The newly synthesized bimetallic nanostructure shows the advantages of low cost, easy synthesis and tunable catalytic activity, making it a promising substitution of enzyme peroxidase in different applications. 相似文献
52.
Morphing Simple Polygons 总被引:2,自引:0,他引:2
In this paper we investigate the problem of morphing (i.e., continuously deforming) one simple polygon into another. We assume
that our two initial polygons have the same number of sides n , and that corresponding sides are parallel. We show that a morph is always possible through an interpolating simple polygon
whose n sides vary but stay parallel to those of the two original ones. If we consider a uniform scaling or translation of part
of the polygon as an atomic morphing step, then we show that O(n log n) such steps are sufficient for the morph. Furthermore, the sequence of steps can be computed in O(n log n) time.
Received May 25, 1999, and in revised form November 15, 1999. 相似文献
53.
We study the following tiling problem in d dimensions: given a d-dimensional rectangular array of nonnegative numbers and an integer p, partition the array into at most p rectangular subarrays so that the maximum weight of any subarray is minimized; the weight of a subarray is the sum of its elements. The rectangular tiling problem is motivated by applications in data mining, data partitioning, and video compression. Recently, Khanna, Muthukrishnan, and Paterson [SODA '98], showed that the tiling problem is NP-complete and gave a 2.5-approximation algorithm for d = 2.In this paper, we extend their result to multidimensional arrays and give an algorithm with approximation ratio
, for d ≥ 2. The algorithm can be implemented to run in worst-case time O(N + p log N) time, where N is the size of the array, and the constant is of the order d!. We also obtain a similar algorithm for the dual tiling problem, where the goal is to compute a tiling of weight at most W using as few tiles as possible. Our algorithm yields an approximation factor (2d + 1).We implemented our algorithm and ran simulation tests on multidimensional arrays with random data. In our limited experiments, the algorithm always produced approximations that were no worse than factor two from the optimal. 相似文献
54.
John Hershberger Subhash Suri 《Journal of Algorithms in Cognition, Informatics and Logic》1996,21(3):453-475
We achieve anO(log n) amortized time bound per operation for the off-line version of the dynamic convex hull problem in the plane. In this problem, a sequence ofninsert,delete, andqueryinstructions are to be processed, where each insert instruction adds a new point to the set, each delete instruction removes an existing point, and each query requests a standard convex hull search. We process the entire sequence in totalO(n log n) time andO(n) space. Alternatively, we can preprocess a sequence ofninsertions and deletions inO(n log n) time and space, then answer queries in history inO(log n) time apiece (a query in history means a query comes with a time parametert, and it must be answered with respect to the convex hull present at timet). The same bounds also hold for the off-line maintenance of several related structures, such as the maximal vectors, the intersection of half-planes, and the kernel of a polygon. Achieving anO(log n) per-operation time bound for theon-lineversions of these problems is a longstanding open problem in computational geometry. 相似文献
55.
Fork/join stations are commonly used to model the synchronization constraints in queuing models of computer networks, fabrication/assembly systems and material control strategies for manufacturing systems. This paper presents an exact analysis of a fork/join station in a closed queuing network with inputs from servers with two-phase Coxian service distributions, which models a wide range of variability in the input processes. The underlying queue length and departure processes are analyzed to determine performance measures such as throughput, distributions of the queue length and inter-departure times from the fork/join station. The results show that, for certain parameter settings, variability in the arrival processes has a significant impact on system performance. The model is also used to study the sensitivity of performance measures such as throughput, mean queue lengths, and variability of inter-departure times for a wide range of input parameters and network populations. 相似文献
56.
57.
In this paper we report measurements of the thermoelectric power on a series of Y1Ba2Cu3O7-x specimens with varying amounts of oxygen deficiency obtained by changing the cooling rate of the sintered specimens. The
specimens have been characterized by X-ray diffraction measurements, electric resistivity and oxygen contents. The temperature
variation of the thermopower reveals a peak just before the onset of superconducting transition. We examine possible theoretical
explanations of this anomaly. In particular we argue that this anomaly is associated with the pairing fluctuations in the
normal state close toT
c
. We present some theoretical results in support of this conclusion. 相似文献
58.
P. N. Bajaj K. G. Manohar B. M. Suri K. Dasgupta R. Talukdar P. K. Chakraborti P. R. K. Rao 《Applied physics. B, Lasers and optics》1988,47(1):55-59
Using two pulsed tunable dye lasers, a two colour multiphoton ionization process has been utilised to explore the higher energy levels of uranium. One hundred and thirty eight new UI levels have been observed in the 37540–38420 cm–1 region. J assignments of these levels have been suggested on the basis of their excitation from intermediate levels with known and contiguous J values. In eight cases the J assignments are unique. 相似文献
59.
Summary.
We consider the mixed formulation for the
elasticity problem and the limiting
Stokes problem in ,
.
We derive a set of sufficient conditions under which families of
mixed finite element spaces
are simultaneously stable with respect to the mesh size
and, subject to a
maximum loss of
,
with respect to the polynomial
degree .
We obtain asymptotic
rates of convergence that are optimal up to
in the
displacement/velocity and up to
in the
"pressure", with
arbitrary
(both rates being
optimal with respect to
). Several choices of
elements are discussed with reference to
properties desirable in the
context of the -version.
Received
March 4, 1994 / Revised version received February 12, 1995 相似文献
60.
Popovici M Gich M Roig A Casas L Molins E Savii C Becherescu D Sort J Suriñach S Muñoz JS Baró MD Nogués J 《Langmuir : the ACS journal of surfaces and colloids》2004,20(4):1425-1429
Monoliths of iron oxide-silica aerogel nanocomposites have been synthesized using a novel synthesis route which consists of impregnating silica wet gels with anhydrous iron(II) precursors followed by ethanol supercritical drying of the gels. The process yields aerogels exhibiting high porosity, large surface areas (approximately 900 m2/g), rather low densities (approximately 0.6 g/cm3), and a homogeneous distribution of single-phase maghemite, gamma-Fe2O3, nanoparticles with average sizes in the 7-8 nm range. Remarkably, the gamma-Fe2O3 nanoparticles are obtained in the as-dried state without the need of postannealing. The nanoparticles are mostly superparamagnetic at room temperature but become blocked in a ferrimagnetic state at lower temperatures. 相似文献