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101.
102.
C. M. Castaneda R. Gearhart B. Sanii P. A. J. Englert D. M. Drake R. C. Reedy 《Journal of Radioanalytical and Nuclear Chemistry》1992,160(2):387-393
Planetary gamma-ray spectroscopy can be used to chemically analyze the top soil from planets in future planetary missions. The production from inelastic neutron interaction plays an effective role in the determination on the C and H at the surface. The gamma-ray production cross section from the strongest lines excited in the neutron bombardment of Fe have been measured by the use of a time analyzed quasi-mono-energetic neutron beam and a high purity germanium detector. The results from En=6.5, 32, 43, and 65 MeV are presented. 相似文献
103.
V.A. Smalyuk O.A. Hurricane J.F. Hansen G. Langstaff D. Martinez H.-S. Park K. Raman B.A. Remington H.F. Robey O. Schilling R. Wallace Y. Elbaz A. Shimony D. Shvarts C. Di Stefano R.P. Drake D. Marion C.M. Krauland C.C. Kuranz 《High Energy Density Physics》2013,9(1):47-51
Kelvin–Helmholtz (KH) turbulent mixing measurements were performed in experiments on the OMEGA Laser Facility [T.R. Boehly et al., Opt. Commun. 133 (1997) 495]. In these experiments, laser-driven shock waves propagated through low-density plastic foam placed on top of a higher-density plastic foil. Behind the shock front, lower-density foam plasma flowed over the higher-density plastic plasma. The interface between the foam and plastic was KH unstable. The experiments were performed with pre-imposed, sinusoidal 2D perturbations, and broadband 3D perturbations due to surface roughness at the interface between the plastic and foam. KH instability growth was measured using X-ray, point-projection radiography. The mixing layer caused by the KH instability with layer width up to ~100 μm was observed at a location ~1 mm behind the shock front. The measured mixing layer width was in good agreement with simulations using a K–L turbulent mixing model in the two-dimensional ARES hydrodynamics code. In the definition of the K–L model K stands for the specific turbulent kinetic (K) energy, and L for the scale length (L) of the turbulence. 相似文献
104.
Joachim Mohn Christina Biasi Samuel Bodé Pascal Boeckx Paul J. Brewer Sarah Eggleston Heike Geilmann Myriam Guillevic Jan Kaiser Kristýna Kantnerová Heiko Moossen Joanna Müller Mayuko Nakagawa Ruth Pearce Isabell von Rein David Steger Sakae Toyoda Wolfgang Wanek Sarah K. Wexler Naohiro Yoshida Longfei Yu 《Rapid communications in mass spectrometry : RCM》2022,36(13):e9296
105.
The surface enhanced resonance Raman spectra of three modified carboxy-x-rhodamine dyes were recorded using Au nanoparticles
and an excitation laser operating at 670 nm. The dyes were modified with a linker group designed both to increase the surface
enhanced Raman spectroscopy signal and to couple the dye to the Au nanoparticles surface. The maximum signal intensity was
recorded for a Cys-Gly linker with Cys thiol group acting as the coupling point to the Au surface and Gly-NH2 group used to attach the carboxy-x-rhodamine dye. This gave a signal intensity in the 1503 cm−1 Raman peak that was more than 20 times greater than for the unmodified dye. The Au nanoparticles used had a diameter of 49.8
± 1.2 nm and were synthesised by the citrate reduction method. 相似文献
106.
Vicinal (1)H--(1)H coupling constants were used to determine the conformational preferences of 2,3-dihydroxypropanoic acid (1) (DL-glyceric acid) in various solvents and its different carboxyl ionization states. The stereospecific assignments of J(12) and J(13) were confirmed through the point-group substitution of the C-3 hydrogen with deuterium, yielding rac-(2SR,3RS)-[3-(2)H]-1, and the observation of only J(13) in the (1)H NMR spectra. While hydrogen bonding and steric strain may be expected to drive the conformational equilibrium, their role is overshadowed by a profound gauche effect between the vicinal hydroxyl groups that mimics other substituted ethanes, such as 1,2-ethanediol and 1,2-difluoroethane. At low pH, the conformational equilibrium is heavily weighted toward the gauche-hydroxyl rotamers with a range of 81% in DMSO-d(6) to 92% in tert-butyl alcohol-d(10). At high pH, the equilibrium exhibits a larger dependence upon the polarity and solvating capability of the medium, although the gauche effect still dominates in D(2)O, 1,4-dioxane-d(8), methanol-d(4), and ethanol-d(6) (96, 89, 85, and 83% gauche-hydroxyls respectively). The observed preference for the gauche-hydroxyl rotamers is believed to stem primarily from hyperconjugative sigma(C--H) --> sigma*(C--OH) interactions. 相似文献
107.
Drake IJ Zhang Y Gilles MK Teris Liu CN Nachimuthu P Perera RC Wakita H Bell AT 《The journal of physical chemistry. B》2006,110(24):11665-11676
Aluminum coordination in the framework of USY and ZSM-5 zeolites containing charge-compensating cations (NH4+, H+, or Cu+) was investigated by Al K-edge EXAFS and XANES. This work was performed using a newly developed in-situ cell designed especially for acquiring soft X-ray absorption data. Both tetrahedrally and octahedrally coordinated Al were observed for hydrated H-USY and H-ZSM-5, in good agreement with 27Al NMR analyses. Upon dehydration, water desorbed from the zeolite, and octahedrally coordinated Al was converted progressively to tetrahedrally coordinated Al. These observations confirmed the hypothesis that the interaction of water with Br?nsted acid protons can lead to octahedral coordination of Al without loss of Al from the zeolite lattice. When H+ is replaced with NH4+ or Cu+, charge compensating species that absorb less water, less octahedrally coordinated Al was observed. Analysis of Al K-edge EXAFS data indicates that the Al-O bond distance for tetrahedrally coordinated Al in dehydrated USY and ZSM-5 is 1.67 angstroms. Simulation of k3chi(k) for Cu+ exchanged ZSM-5 leads to an estimated distance between Cu+ and framework Al atoms of 2.79 angstroms. 相似文献
108.
H. G. Eggleston 《Israel Journal of Mathematics》1963,1(3):149-155
It is shown that any plane set of constant unit width contains a semi-circle of radius 1/2, and using this a minimal univeral
plane cover is explicitly constructed. It is also shown that in an n-dimensional space with n>2 there are minimal universal
covers of arbitrary large diameter.
This paper was written while the author was a National Science Foundation Visiting Senior Fellow at the University of Washington,
Seattle, Washington, U.S.A. 相似文献
109.
110.