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1.
BIT Numerical Mathematics - In this article we address the problem of minimizing a strictly convex quadratic function using a novel iterative method. The new algorithm is based on the well-known... 相似文献
2.
Jonathan L. Sessler Patricia J. Melfi Anne E.V. Gorden Doris K. Ford C. Drew Tait 《Tetrahedron》2004,60(49):11089-11097
Hexaphyrin(1.0.1.0.0.0) (isoamethyrin) undergoes a significant color change in the presence of UO22+, PuO22+, and NpO22+. The complexation of the first of these dioxo actinide cations was studied in semi-quantitative fashion in 1:1 MeOH-CH2Cl2. Under these conditions, the detection limit for UO22+ was found to be ca. 5.8 ppm by naked eye monitoring and <28 ppb by UV-vis spectroscopy. Isoamethyrin does not undergo a color change in the presence of most transition metals or when exposed to Gd(III). Isoamethyrin thus constitutes an attractive alternative to 2,2′(1,8-dihydroxy-3,6-disulfonaphthylene-2,7-bisazo)-bisbenzenarsonic acid (AzIII) and 2-(5-bromo-2-pyridylazo)-5-(diethylamino)phenol (BrPADAP), systems currently used as actinide cation sensors. 相似文献
3.
Two thousand images of resolution 512×512 pixels as a regular matrix pattern of 10×10 elements are stored, where each element is angularly multiplexed 20 times in a 25 μm thickness of dichromated gelatin emulsion without cross-talk effect. The surface area of the matrix is 1 cm2. We show good concordance of the angular selectivity between the experimental result and theory. The diffraction efficiency of each 20 multiplexed images is measured and has nearly the same value. Examples of reconstructed images for multiple applications are given, for example, storage of 160,000 images on a 3′1/2 floppy disc format, which is about 100 min of black and white film. Application can be made to automobile cartography and storage of X-ray images as well as weather forecast images. Colored diffractive images are also possible and are illustrated. 相似文献
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Milind Choubal Warren T. Ford 《Journal of polymer science. Part A, Polymer chemistry》1989,27(6):1873-1882
Crosslinked polystyrene latexes with high surface charge densities have been prepared with 1, 3, and 5 mol% divinylbenzene and 0.5–5.0 mol% of 12-(o-styryloxy)dodecyltrimethylammonium bromide ( 1 ). Within experimental error all of surfactant 1 was incorporated into the particles. Analysis of the latex particles by transmission electron microscopy showed nonspherical shapes, aggregates, and number average diameters ranging from 22 to 95 nm. The particle size decreases and the polydispersity increases with increasing amounts of surfactant 1 and of divinylbenzene in the monomer mixture. A mechanism is proposed for particle formation by precipitation of crosslinked polymer from monomer droplets to form primary particles, coagulation of the primary particles to colloidally stable aggregates, and growth by further polymerization. 相似文献
9.
Summary The pH versus fluorescence intensity profiles of a series of new pH-indicators are reported. They are characterized by two pKa-values in the 3.7–4.9 and 6.9–7.9 range, respectively. The strong change in fluorescence intensity with pH allows the determination of pH's over a much wider range (typically 2–9) than with one-step indicators. They are therefore considered to be of potential utility for measurement of pH over the neutral and slightly acidity range which occurs, for instance, in bioliquids such as urine.
Eine neue Gruppe fluorescierender pH-Indicatoren für einen erweiterten pH-Bereich
Zusammenfassung Die Fluorescenzintensitätsprofile als Funktion des pH-Wertes einer Reihe von neuen pH-Indicatoren werden untersucht. Sie sind charakterisiert durch zwei pKa-Werte im Bereich 3,7–4,9 bzw. 6,9–7,9. Die gefundene starke Änderung der Fluorescenzintensität mit dem pH-Wert erlaubt eine pH-Bestimmung über einen viel weiteren Bereich (typischerweise 2 – 9) als mit einstufigen Indicatoren. Aus diesem Grund werden sie als potentiell nützlich angesehen zur Messung von pH-Werten im neutralen und schwach sauren Bereich, wie er z.B. in biologischen Flüssigkeiten, etwa im Urin, gegeben ist.相似文献
10.
We generalize a variational principle for the mean spherical approximation for a system of charged hard spheres in 3D to arbitrary
dimensions. We first construct a free energy variational trial function from the Debye-Hückel excess charging internal energy
at a finite concentration and an entropy obtained at the zero-concentration limit by thermodynamic integration. In three dimensions
the minimization of this expression with respect to the screening parameter leads to the mean spherical approximation, usually
obtained by solution of the Ornstein-Zernike equation. This procedure, which interpolates naturally between the zero concentration/coupling
limit and the high-concentration/ coupling limit, is extended to arbitrary dimensions. We conjecture that this result is also
equivalent to the MSA as originally defined, although a technical proof of this point is left for the future. The Onsager
limitT ΔS
MSA
/ΔE
MSA
→ 0 for infinite concentration/coupling is satisfied for all d ≠ 2, while ford=2 this limit is 1.
On leave from Department of Physics, University of Puerto Rico, Mayagüez Campus, Mayagüez, Puerto Rico, 00681. 相似文献