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31.
32.
N. Graneau T. Phipps Jr D. Roscoe 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2001,15(1):87-97
According to the conventional views of electromagnetic theory, as these are expressed in the Lorentz force law, all the forces
which act on a current carrying metallic conductor are perpendicular to the current streamlines. However, over the years,
from Ampère through Maxwell until the present day, there have been persistent claims that when current flows in a metallic
conductor, there are mechanical forces acting along current streamlines which subject the conductor to tensile stress, and
which are therefore capable of performing work in the direction of current flow. The problem of substantiating these claims
has always lain in the difficulty of designing an experiment in which the effects are unambiguously demonstrated. The present
paper describes an experiment which to a large extent removes these ambiguities, and which provides a compelling novel demonstration
of forces acting along current streamlines. A force calculation based on Ampère's original electrodynamic force law is found
to be consistent with the observed behaviour.
Received 15 November 2000 and Received in final form 12 March 2001 相似文献
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Ahmed Z Akerib DS Arrenberg S Bailey CN Balakishiyeva D Baudis L Bauer DA Brink PL Bruch T Bunker R Cabrera B Caldwell DO Cooley J do Couto e Silva E Cushman P Daal M DeJongh F Di Stefano P Dragowsky MR Duong L Fallows S Figueroa-Feliciano E Filippini J Fox J Fritts M Golwala SR Hall J Hennings-Yeomans R Hertel SA Holmgren D Hsu L Huber ME Kamaev O Kiveni M Kos M Leman SW Liu S Mahapatra R Mandic V McCarthy KA Mirabolfathi N Moore D Nelson H Ogburn RW Phipps A Pyle M Qiu X Ramberg E Rau W 《Physical review letters》2011,106(13):131302
We report results from a reanalysis of data from the Cryogenic Dark Matter Search (CDMS II) experiment at the Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with a lowered, 2 keV recoil-energy threshold, to give increased sensitivity to interactions from weakly interacting massive particles (WIMPs) with masses below ~10 GeV/c(2). This analysis provides stronger constraints than previous CDMS II results for WIMP masses below 9 GeV/c(2) and excludes parameter space associated with possible low-mass WIMP signals from the DAMA/LIBRA and CoGeNT experiments. 相似文献
36.
37.
Saltiel J Krishna TR Laohhasurayotin K Ren Y Phipps K Davis PH Yee WA 《The journal of physical chemistry. A》2011,115(11):2120-2129
Quantum yields for the photoisomerization of trans,trans-1,4-diphenyl-1,3-butadiene (tt-DPB), determined in benzene, cyclohexane, methylcyclohexane, hexane, and perfluorohexane, confirm the low values reported earlier for benzene and cyclohexane and reveal even lower values in the last two solvents. In contrast to trans-stilbene (t-St), fluorescence and torsional relaxation leading to photoisomerization do not account exclusively for S(1)tt-DPB decay. Competing radiationless singlet excited-state decay pathways exist in tt-DPB, which do not lead to photoisomerization and may not involve large-amplitude torsional motions. Our results invalidate analyses of tt-DPB fluorescence quantum yields and lifetimes that assign all radiationless decay to the isomerization channel. Gas-phase chromatography analysis of tt-DPB photoisomerization in hexane shows the reaction to be concentration-independent and reveals, for the first time, a significant, two-bond photoisomerization pathway, φ(tt→tc) = 0.092 and φ(tt→cc) = 0.020. The dominant one-bond-twist (OBT) process is accompanied by a bicycle pedal (BP) process that accounts for almost 20% of tt-DPB photoisomerization. The OBT tt-DPB photoisomerization quantum yield is largest in benzene (Bz) and smallest in perfluorohexane (PFH). Contrary to expectations, reduction in medium friction in PFH is accompanied by a decrease in φ(tt→tc). The 1(1)B(u)/2(1)A(g) order and energy gap appear to control the contribution of torsional relaxation to radiationless decay. Lowering the 1(1)B(u) energy as in Bz favors photoisomerization. Reversal of the 1(1)B(u)/2(1)A(g) order in PFH is accompanied by short τ(f) and small φ(f) and φ(tt→tc) values that suggest the presence of competing 2(1)A(g) → 1(1)Ag relaxation paths that are unproductive with respect to photoisomerization. We conclude that the Birks extension to diphenylpolyenes of the Orlandi-Siebrand cis-trans photoisomerization mechanism is not valid. Photoisomerization appears to occur in the 1(I)B(u) state, and we argue that this applies to t-St as well. 相似文献
38.
T Honjo RJ Phipps V Rauniyar FD Toste 《Angewandte Chemie (International ed. in English)》2012,51(38):9684-9688
Double agent: Enantioselective tandem oxyfluorination of enamides using a doubly axially chiral phosphoric acid catalyst is reported. The chiral phosphoric acid catalyst controls both a fluorination step, using a chiral anion phase-transfer strategy, and addition to the resulting imine under the guise of Br?nsted acid catalysis. 相似文献
39.
Nino R. Pereira B.V. Weber D.G. Phipps J.W. Schumer J.F. Seely J.J. Carroll J.R. Vanhoy K. Słabkowska M. Polasik E. Szymańska J. Rzadkiewicz 《High Energy Density Physics》2013,9(3):500-504
A recent measurement [1] demonstrates that iridium's Kα2-line, centered at ?63286.96 eV for a cold atom, increases ?+10 eV in energy when it is emitted by a modestly (~17×) ionized plasma. This measurement, enabled by a near-coincident lutetium K-edge filter, agrees well with atomic physics computations. Not understood at the time was a similar measurement with a thulium filter at the ?59370 eV energy of ytterbium's Kβ1 line, which indicated that its photon energy decreases with ionization. The computation reported here shows that the ionization energy shift for Yb's Kβ lines is indeed negative and agrees qualitatively with the measurements. For the K-lines the ionization energy shift may be most interesting in atomic physics, while for the L-lines the ionization energy shift is a promising plasma diagnostic [2]. 相似文献
40.
Dale E. Phipps 《Tetrahedron letters》2009,50(26):3454-129
A novel [2]catenane is synthesized in good yield from an upper-rim functionalized calix[4]arene macrobicycle and a nitro-substituted isophthalamide threading component in the presence of a chloride anion template via a ring-closing metathesis (RCM) reaction. After halide anion template removal the resulting catenane host exhibits a high degree of selectivity for chloride in competitive organic solvent mixtures. 相似文献