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31.
Dvinskikh SV Zimmermann H Maliniak A Sandström D 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2004,168(2):5967-201
A novel MAS NMR approach is presented for the determination of heteronuclear dipolar couplings in unoriented materials. The technique is based on the proton-detected local field (PDLF) protocol, and achieves dipolar recoupling by R-type radio-frequency irradiation. The experiment, which is called R-PDLF spectroscopy, is demonstrated on solid and liquid-crystalline systems. For mobile systems, it is shown that the R-PDLF scheme provides better dipolar resolution as compared to techniques combining conventional separated local field (SLF) spectroscopy with R-type recoupling. 相似文献
32.
Kastelein RA Hagedoorn M Au WW de Haan D 《The Journal of the Acoustical Society of America》2003,113(2):1130-1137
The underwater hearing sensitivity of a striped dolphin was measured in a pool using standard psycho-acoustic techniques. The go/no-go response paradigm and up-down staircase psychometric method were used. Auditory sensitivity was measured by using 12 narrow-band frequency-modulated signals having center frequencies between 0.5 and 160 kHz. The 50% detection threshold was determined for each frequency. The resulting audiogram for this animal was U-shaped, with hearing capabilities from 0.5 to 160 kHz (8 1/3 oct). Maximum sensitivity (42 dB re 1 microPa) occurred at 64 kHz. The range of most sensitive hearing (defined as the frequency range with sensitivities within 10 dB of maximum sensitivity) was from 29 to 123 kHz (approximately 2 oct). The animal's hearing became less sensitive below 32 kHz and above 120 kHz. Sensitivity decreased by about 8 dB per octave below 1 kHz and fell sharply at a rate of about 390 dB per octave above 140 kHz. 相似文献
33.
Dvinskikh SV Zimmermann H Maliniak A Sandström D 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2003,164(1):165-170
A pulse sequence is described for the recoupling of heteronuclear dipolar interactions under MAS. The method is similar to the PISEMA experiment, but employs a well-defined amplitude modulation of one of the two radio-frequency fields. The technique is used for measurements of 1H-13C dipolar couplings in unoriented solid and liquid-crystalline samples. 相似文献
34.
Complex tree-like nanostructures with controlled morphology are becoming increasingly important for the development of nanoscale
devices. The position of branches on III–V semiconductor nanotrees is determined by the distribution of Au seed particles.
Here we report the dependence of the distribution of Au aerosol nanoparticles on nanowires on parameters including distance
between wires, particle size, wire length, wire diameter, III–V material and particle charge. It was observed that different
wire lengths and separation distances as well as different particle polarities have a significant effect on the resulting
particle distribution while different wire diameters, particle diameters, materials and deposition voltages do not. 相似文献
35.
J. Dick und A. Rudner 《Fresenius' Journal of Analytical Chemistry》1934,96(7-8):245-248
Ohne Zusammenfassung 相似文献
36.
Dick Hoekzema 《Foundations of Physics》1987,17(8):787-797
Two types of contextual theories are distinguished and shown to be related. For theories of each type a criterion of locality is formulated which is weaker than the classical requirement of separability at spacelike intervals. The relations between the concepts of locality, realism, and ontic chance are discussed. 相似文献
37.
E. Dick 《Applied Scientific Research》1982,39(4):321-328
Galerkin finite element methods based on symmetric weighting functions give oscillations in the solution of steady Navier-Stokes equations when the Reynolds number is large. To overcome this difficulty Galerkin methods with asymmetric weighting functions can be used. In the present paper a critical test case is calculated with this so-called Petrov-Galerkin method. Comparison between calculations and experiments proofs that the accuracy of the method is good, even for a Reynolds number based on mesh size as high as two hundred. 相似文献
38.
Ferry Heus Martin Giera Gerdien E. de Kloe Dick van Iperen Joost Buijs Tariq T. Nahar August B. Smit Henk Lingeman Iwan J. P. de Esch Wilfried M. A. Niessen Hubertus Irth Jeroen Kool 《Analytical and bioanalytical chemistry》2010,398(7-8):3023-3032
One way to profile complex mixtures for receptor affinity is to couple liquid chromatography (LC) on-line to biochemical detection (BCD). A drawback of this hyphenated screening approach is the relatively high consumption of sample, receptor protein and (fluorescently labeled) tracer ligand. Here, we worked toward minimization of sample and reagent consumption, by coupling nano-LC on-line to a light-emitting diode (LED) based capillary confocal fluorescence detection system capable of on-line BCD with low-flow rates. In this fluorescence detection system, a capillary with an extended light path (bubble cell) was used as a detection cell in order to enhance sensitivity. The technology was applied to a fluorescent enhancement bioassay for the acetylcholine binding protein, a structural analog of the extracellular ligand-binding domain of neuronal nicotinic acetylcholine receptors. In the miniaturized setup, the sensitive and low void volume LED-induced confocal fluorescence detection system operated in flow injection analysis mode allowing the measurement of IC50 values, which were comparable with those measured by a conventional plate reader bioassay. The current setup uses 50 nL as injection volume with a carrier flow rate of 400 nL/min. Finally, coupling of the detection system to gradient reversed-phase nano-LC allowed analysis of mixtures in order to identify the bioactive compounds present by injecting 10 nL of each mixture. 相似文献
39.
Coensel BD Vanwetswinkel S Botteldooren D 《The Journal of the Acoustical Society of America》2011,129(4):EL148-EL153
Recent studies show that introducing sound from water features in urban open spaces may reduce the loudness of road traffic noise, but it is not clear in which situations this measure also improves overall soundscape quality. This work describes a listening experiment on loudness, pleasantness, and eventfulness of stimuli that combine road traffic noise with fountain or bird sound at different sound levels. Adding fountain sound reduced the loudness of road traffic noise only if the latter had low temporal variability. Conversely, adding bird sound significantly enhanced soundscape pleasantness and eventfulness, more than what was achieved by adding fountain sound. 相似文献
40.
The problem of minimizing a quadratic objective function subject to one or two quadratic constraints is known to have a hidden convexity property, even when the quadratic forms are indefinite. The equivalent convex problem is a semidefinite one, and the equivalence is based on the celebrated S-lemma. In this paper, we show that when the quadratic forms are simultaneously diagonalizable (SD), it is possible to derive an equivalent convex problem, which is a conic quadratic (CQ) one, and as such is significantly more tractable than a semidefinite problem. The SD condition holds for free for many problems arising in applications, in particular, when deriving robust counterparts of quadratic, or conic quadratic, constraints affected by implementation error. The proof of the hidden CQ property is constructive and does not rely on the S-lemma. This fact may be significant in discovering hidden convexity in some nonquadratic problems. 相似文献