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Ohne Zusammenfassung 相似文献
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155.
Harold P. Benson 《Journal of Global Optimization》1999,15(4):315-342
This article presents a new global solution algorithm for Convex Multiplicative Programming called the Outcome Space Algorithm. To solve a given convex multiplicative program (P
D), the algorithm solves instead an equivalent quasiconcave minimization problem in the outcome space of the original problem. To help accomplish this, the algorithm uses branching, bounding and outer approximation by polytopes, all in the outcome space of problem (P
D). The algorithm economizes the computations that it requires by working in the outcome space, by avoiding the need to compute new vertices in the outer approximation process, and, except for one convex program per iteration, by requiring for its execution only linear programming techniques and simple algebra. 相似文献
156.
Michael J. Benson Christopher J. Elkins Paul D. Mobley Marcus T. Alley John K. Eaton 《Experiments in fluids》2010,49(1):43-55
Magnetic resonance imaging (MRI) was used to measure the three-dimensional, time-averaged concentration distribution in a
turbulent two-stream mixing layer. Test fluids and MRI scanning parameters were chosen to give good signal linearity, and
a calibration/normalization procedure was developed to reduce the concentration measurement uncertainty. Plain deionized water
mixing with a solution of 0.8% gadopentetate dimeglumine in deionized water were selected as test fluids. The concentration
of the marked water was measured on an array of 220,000 0.69 mm3 voxels covering the entire flow apparatus. Planar laser-induced fluorescence experiments were performed on the flow centerplane
to provide validation data. The uncertainty of a single voxel measurement was estimated to be less than 12% with the largest
source of uncertainty being turbulent dephasing. Averaging two runs in which the marked water was switched between the two
streams reduced the uncertainty to only 4%. The complete magnetic resonance concentration (MRC) procedure including the adjustment
of scanning parameters, a background run, two reference/calibration runs, and multiple concentration measurement runs can
be completed in 2–3 h. This work establishes MRC as a viable technique for studying the mixing in complex turbulent liquid
flows. 相似文献
157.
Michael Barth Stefan Schietinger Tim Schröder Thomas Aichele Oliver Benson 《Journal of luminescence》2010,130(9):1628-12578
Nitrogen-vacancy (NV) defect centers in diamond have recently emerged as promising candidates for a number of applications in the fields of quantum optics and quantum information, such as single photon generation and spin qubit operations. The performance of these defect centers can strongly be enhanced through coupling to plasmonic and photonic nanostructures, such as metal particles and optical microcavities. Here, we demonstrate the controlled assembly of such hybrid structures via manipulation with scanning near-field probes. In particular, we investigate the plasmonic enhancement of the single photon emission through coupling to gold nanospheres as well as the coupling of diamond nanocrystals to the optical modes of microsphere resonators and photonic crystal cavities. These systems represent prototypes of fundamental nanophotonic/plasmonic elements and provide control on the generation and coherent transfer of photons on the level of a single quantum emitter. 相似文献
158.
A palmitate biosensor that uses the emission intensity of a semiconducting nanoparticle to report palmitate concentration is presented. This method uses electron transfer to quench the emission from a ZnS-coated CdSe nanoparticle. The fatty acid binding pocket of intestinal fatty acid binding protein is used to modulate the electron transfer properties of [Ru(L)(NH3)4](PF6)2 (L = 5-maleimido-1,10-phenanthroline) that is covalently attached within this pocket. Once the metal-complex-modified protein is attached to ZnS-coated CdSe nanoparticles, palmitate addition excludes water from around the metal complex and increases the electron transfer from the metal complex to the valence band hole of the nanoparticle excited state. A 1.6-fold change in emission intensity is observed upon adding a saturated amount (500 nM) of sodium palmitate. The dissociation constant was calculated as 5 nM with a 1 nM lower limit of detection. Since palmitate does not alter the global conformation of intestinal fatty acid binding protein, palmitate-mediated changes in pocket solvation are suggested. This represents a new method in biosensor construction with semiconducting nanoparticles. Including previous conformation-dependent biosensors, there are thousands of potential analytes that can be detected with these strategies. Such biosensors will provide fluorescence contrast imaging reagents for small molecule analytes. 相似文献
159.
Reagentless and reversible maltose biosensors are demonstrated using ZnS coated CdSe (CdSe@ZnS) nanoparticle emission intensities. This method is based on electron transfer quenching of unimolecular protein-CdSe@ZnS nanoparticle assemblies, which is provided by a protein-attached Ru(II) complex. This Ru(II) complex is presumed to reduce a valence band hole of the CdSe@ZnS excited state by tunneling through the ZnS overcoating. The Ru(II) complex mediated quenching of CdSe@ZnS nanoparticle emission was only decreased 1.2-fold relative to the CdSe nanoparticle systems. While four different Ru(II) complex attachment sites provided different amounts of nanoparticle emission quenching (1.20 to 1.75-fold decrease), all of these attachment sites yielded maltose-dependent intensity changes (1.1 to 1.4-fold increase upon maltose addition). Maltose dissociation constants for these four biosensing systems range from 250 nM to 1.0 microM, which are similar to the maltose-maltose binding protein dissociation constant that these sensors are based on. The increased fluorescence intensity was found to only occur in the presence of maltose. Furthermore, the ability of these reagentless protein-nanoparticle assemblies to perform maltose biosensing reversibly is demonstrated with the addition of alpha-glucosidase. Three 50 microM maltose additions after alpha-glucosidase addition showed increases of 2.2 microM, 600 nM, and 150 nM maltose. This result demonstrates a fluorometric method for examining alpha-glucosidase activity. Using maltose binding protein to control Ru(II) complex interactions with CdSe@ZnS nanoparticle surfaces provide a novel class of highly fluorescent, photostable biosensors that are selective for maltose. 相似文献
160.
Primary amines react with keto-aldehyde functionality located in the side-chain of an eta4-dienetricarbonyliron complex to provide the corresponding pyrrolidines in excellent diastereoselectivity. Two of the pyrrolidine products, 1i and 1k, have been elaborated into pyrrolizidines using a 1,5-C-H insertion and radical cyclization strategy, respectively. 相似文献