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31.
W. C. Burnett G. Kim D. Lane-Smith 《Journal of Radioanalytical and Nuclear Chemistry》2001,249(1):167-172
Radon-222 is a good natural tracer of groundwater flow into the coastalocean. Unfortunately, its usefulness is limited by the time consuming natureof collecting individual samples and traditional analysis schemes. We demonstratehere an automated system which can determine, on a continuousbasis, the radon activity in coastal ocean waters. The system analyses 222Rn from a constant stream of water passing through an air-water exchangerthat distributes radon from the running flow of water to a closed air loop.The air stream is feed to a commercial radon-in-air monitor which determinesthe concentration of 222Rn by collection and measurement of theemitting daughters, 214Po and 218Po, via a charged semiconductordetector. Since the distribution of radon at equilibrium between the air andwater phases is governed by a well-known temperature dependence, the radonconcentration in the water is easily calculated. 相似文献
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Andrew D. Burnett Dr. John Kendrick Dr. John E. Cunningham Dr. Michael D. Hargreaves Dr. Tasmin Munshi Dr. Howell G. M. Edwards Prof. Edmund H. Linfield Prof. A. Giles Davies Prof. 《Chemphyschem》2010,11(2):368-378
The terahertz frequency spectrum of pentaerythritol tetranitrate (PETN) is calculated using Discover 1 with the COMPASS 2 force field, CASTEP[3] and PWscf. 4 The calculations are compared to each other and to terahertz spectra (0.3–3 THz) of crystalline PETN recorded at 4 K. A number of analysis methods are used to characterise the calculated normal modes. 相似文献
34.
J. J. Carroll J. Burnett T. Drummond J. Lepak R. Propri D. Smith S. A. Karamian J. Adam F. Stedile F. J. Agee 《Hyperfine Interactions》2002,143(1-4):37-54
Experiments with the long-lived, high-K isomer 178Hfm2 have been recognized as intriguing tests of multi-quasiparticle state structures and their interactions with external radiation.
A triggered release of the energy stored by this isomer, 2.5 MeV per nucleus or 1.2 GJ/gram, in the form of a gamma-ray burst
might prove valuable for numerous applications. The observation of “accelerated” decay of 178Hfm2 during irradiation by 90-keV bremsstrahlung has already been reported, but with poor statistical accuracy due to the experimental
approach. That approach employed single Ge detectors to seek increases in the areas of peaks at energies corresponding to
transitions in the spontaneous decay of the isomer. The need for better quality data to confirm those results has motivated
the development of improved detection concepts. One such concept was utilized here to perform an initial search for low-energy
(<20 keV) triggered gamma emission from 178Hfm2 using the YSU miniball detector array.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
35.
Bai R Nguyen TL Burnett JC Atasoylu O Munro MH Pettit GR Smith AB Gussio R Hamel E 《Journal of chemical information and modeling》2011,51(6):1393-1404
Compounds that modulate microtubule dynamics include highly effective anticancer drugs, leading to continuing efforts to identify new agents and improve the activity of established ones. Here, we demonstrate that [(3)H]-labeled halichondrin B (HB), a complex, sponge-derived natural product, is bound to and dissociated from tubulin rapidly at one binding site per αβ-heterodimer, with an apparent K(d) of 0.31 μM. We found no HB-induced aggregation of tubulin by high-performance liquid chromatography, even following column equilibration with HB. Binding of [(3)H]HB was competitively inhibited by a newly approved clinical agent, the truncated HB analogue eribulin (apparent K(i), 0.80 μM) and noncompetitively by dolastatin 10 and vincristine (apparent K(i)'s, 0.35 and 5.4 μM, respectively). Our earlier studies demonstrated that HB inhibits nucleotide exchange on β-tubulin, and this, together with the results presented here, indicated the HB site is located on β-tubulin. Using molecular dynamics simulations, we determined complementary conformations of HB and β-tubulin that delineated in atomic detail binding interactions of HB with only β-tubulin, with no involvement of the α-subunit in the binding interaction. Moreover, the HB model served as a template for an eribulin binding model that furthered our understanding of the properties of eribulin as a drug. Overall, these results established a mechanistic basis for the antimitotic activity of the halichondrin class of compounds. 相似文献
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We report observation of the scattered spectrum from a Zeeman degenerate atom at high laser intensities. For a J = 0 to J = 1 transition in the presence of collisions we observe an asymmetric triplet in the polarization parallel to the incident laser and an asymmetric doublet in the polarization perpendicular to the incident laser. 相似文献
38.
Gd2O3 particles (less than 2 microns) in suspension were evaluated as a potential contrast agent for liver-spleen imaging with magnetic resonance. The agent was administered IV to rabbits in doses ranging from 10 to 120 mumol/kg and the tissues removed after sacrifice for in vitro T1 and T2 analysis. The temporal response was determined in liver and spleen samples of rabbits given a fixed dose (60 mumol/kg) and sacrificed at intervals from 15 min to 60 hr later. Documentation of the subanatomic location of Gd2O3 particles in tissue was accomplished by electron microscopy and x-ray dispersion microanalysis. T1 weighted images were obtained at 0.12T on a prototype resistive scanner. The liver, spleen, and lung relaxation times are very responsive to Gd2O3 IV and the effect is dose related. A peak effect is observed between 3-7 hr after injection and relaxation times may normalize by 60 hr. By electron microscopic and x-ray analysis, Gd2O3 is most prominently found in the hepatic and splenic sinusoids. The images show marked enhancement of liver and splenic tissues, aiding in the clear delineation of these tissues from neighboring structures. 相似文献
39.
Recent experimental observation of induced scattering of CO2 laser radiation by an underdense hydrogen plasma can be explained theoretically by non-linear and Compton scattering from ions in the highly cooperative plasma conditions prevailing (kλD? 1). 相似文献
40.