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D. Bisello G. Busetto A. Castro M. Nigro M. Penzo L. Pescara M. Posocco P. Sartori L. Stanco Z. Ajaltouni A. Falvard J. Jousset B. Michel J. C. Montret A. Antonelli R. Baldini A. Calcaterra G. Capon M. Schioppa J. -E. Augustin G. Cosme F. Couchot B. Dudelzak F. Fulda G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne V. Lepeltier F. Manè C. Paulot R. Riskalla Ph. Roy G. Szklarz DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1988,39(1):13-19
Thee + e ?→K + K ? cross section has been measured from about 750 events in the energy interval \(1350 \leqq \sqrt s \leqq 2400 MeV\) with the DM2 detector at DCI. TheK ± form factor |F F ±| cannot be explained by the ρ, ω, ? and ρ′(1600). An additional resonant amplitude at 1650 MeV has to be added as suggested by a previous experiment. 相似文献
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J. -E. Augustin G. Cosme F. Couchot B. Dudelzak F. Fulda B. Grelaud G. Grosdidier B. Jean-Marie S. Jullian D. Lalanne V. Lepeltier B. Louis F. Mané C. Paulot R. Riskalla Ph. Roy F. Rumpf G. Szklarz Z. Ajaltouni A. Falvard J. Jousset B. Michel J. C. Montret R. Baldini S. Calcaterra G. Capon D. Bisello G. Busetto S. Limentani M. Nigro L. Pescara M. Posocco P. Sartori L. Stanco DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1987,36(3):369-376
The radiative decayJ/ψ → γ π+ π? has been studied using the 8.6 millionJ/ψ produced in the DM2 experiment at the DCIe +e? storage rings at Orsay. The π+ π? mass spectrum shows a cleanf 2 (1270) signal, and the possible presence of two other states at thef 2 (1720) andf 4 (2030) masses. For thef 2 (1270), the branching ratio BR(J/ψ →γf)xBR(f→π+ π?) is measured to be (7.50±0.30±1.12)×10?4, and the spin analysis prefers theJ=2 assignment, with helicity parametersx=0.83±0.06 andy=0.01±0.06. The existence of higher mass states is discussed. 相似文献
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The steady propagation of a thin smouldering front in a half-spacehas been considered. A suitable coordinate transformation hasallowed the region near the leading edge of the front to beexamined for both a maintained planar surface and with surfacecollapse due to material shrinkage. The change in the oxidizerconcentration for a small increment in the propagation speedfor large time and surface collapse has been determined. Theinfluence of two types of nonlinear diffusion on the shape ofthe smouldering front has been found; other cases can be dealtwith in a similar manner. 相似文献
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The effect of acidic pH on the translocation of single-stranded DNA through the α-hemolysin pore is investigated. Two significantly different types of events, i.e. deep blockades and shallow blockades, are observed at low pH. The residence times of the shallow blockades are not significantly different from those of the DNA translocation events obtained at or near physiological pH, whereas the deep blockades have much larger residence times and blockage amplitudes. With a decrease in the pH of the electrolyte solution, the percentage of the deep blockades in the total events increases. Furthermore, the mean residence time of these long-lived events is dependent on the length of DNA, and also varies with the nucleotide base, suggesting that they are appropriate for use in DNA analysis. In addition to being used as an effective approach to affect DNA translocation in the nanopore, manipulation of the pH of the electrolyte solution provides a potential means to greatly enhance the sensitivity of nanopore stochastic sensing. 相似文献
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D. M. M. Krishantha R. M. G. Rajapakse D. T. B. Tennakoon H. V. R. Dias 《Ionics》2006,12(4-5):287-294
Investigation of the electrical properties of polymer–clay nanocomposites is important in the development of nanoelectronic devices. These nanocomposites may be prepared by intercalating suitable monomers within interlayer spaces of expanding layered clay materials, followed by in situ polymerization. We made use of this approach to prepare montmorillonite–polyaniline nanocomposites by ion-exchanging the intergallery cations for anilinium ions and subsequently polymerizing the anilinium ions by peroxydisulphate in the acidic medium to yield emeraldine salt form of polyaniline intercalated in montmorillonite (ES1-MMT). The emeraldine salt form of polyaniline contains one positive charge per three monomer units, and hence, polymerization of anilinium ions reduces the number of cations present within the interlayer. Charge compensation thus requires uptake of required amount of cations from the solution. Further, the emeraldine salt form of polyaniline can be neutralized by treating with excess base such as ammonia. Thus, the neutralization of emeraldine salt results in an uptake of ammonium ions for charge balance. We have, therefore, neutralized ES1-MMT using aqueous ammonium hydroxide, and the cations inserted into the interlayer were again exchanged for anilinium ions. The latter was polymerized in acidic medium to yield more polyaniline in its emeraldine salt form (ES2-MMT). By repeating this procedure we have also prepared ES3-MMT. X-ray diffraction (XRD) spectra recorded at 150 °C reveal the enhancement of d-spacing upon increased amounts of polymer formation, and the Fourier transform infrared (FTIR) analysis also supports this by showing enhanced absorption due to bands typical of emeraldine salt (for example, B–NH+ = Q, where B and Q stand for benzanoid and quinoid, respectively). Careful analyses of FTIR spectra reveal that the polymer is present within the interlayers, as well as adsorbed onto the external surfaces and is bound to clay layers through hydrogen bonding. In this publication, we report the electrical properties of such ES-MMT nanocomposites. Alternating current (AC) impedance analysis shows that the nanocomposites are highly conducting materials, and their bulk conductivity enhances in the order ES1-MMT < ES2-MMT < ES3-MMT. The materials are pure electronic conductors as revealed by the direct current polarization studies. Further, their conductivities decrease with increasing temperature as of pure electronic conductors. By treating kaolinite with anilinium ions in acidic medium followed by peroxydisulphate ions, emeraldine salt–kaolinite (ES-KAL) composites have also been prepared. Because kaolinite is a non-expanding clay, the ion exchange is not possible, and hence, the polymer cannot be incorporated into the interlayer. This is indeed shown in the XRD analysis. The polymer can only reside out of the kaolinite particles. FTIR spectra reveal the hydrogen bonding between the polymer and kaolinite outer surfaces. AC impedance spectra of ES-KAL do not show high bulk conductivity. Thus, the comparison of AC impedance spectra of ES-KAL with ES-MMT systems clearly indicates that the bulk conductivity of the latter systems is predominantly due to intercalated polyaniline. 相似文献
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D. Bisello G. Busetto A. Castro M. Nigro L. Pescara M. Posocco P. Sartori L. Stanco A. Antonelli M. E. Biagini R. Baldini A. Calcaterra M. Schioppa J. E. Augustin G. Cosme F. Couchot F. Fulda G. Grosdidier B. Jean-Marie V. Lepeltier G. Szklarz DM Collaboration 《Zeitschrift fur Physik C Particles and Fields》1990,48(1):23-28
Search for baryon pairs production ine + e ? annihilation at \(\sqrt s = 2386 MeV\) is reported. The data relate to a luminosity of 161 nb?1 collected by the DM2 experiment at DCI, the Orsay colliding ring. First measurements of directe + e ? annihilation into \(\Lambda \bar \Lambda \) and ofe + e ?→ \(p\bar p\) at this energy are presented. First observation of a goode + e ?→ \(n\bar n\) candidate is reported and upper limits are given fore + e ?→ \(n\bar n, \Lambda \bar \sum ^0 + c.c.\) and \(\Sigma ^0 \bar \Sigma ^0 \) . 相似文献
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Molecular weights of {[3,5-(CF 3) 2Pz]Ag} 3, {[3-(C 3F 7),5-( t-Bu)Pz]Ag} 3, and {[3,5-( i-Pr) 2Pz]Ag} 3 at various solution concentrations have been investigated using vapor-pressure osmometry. Depending on the concentration, the trinuclear {[3,5-(CF 3) 2Pz]Ag} 3 either dissociates into mono- and dinuclear moieties or remains trinuclear or aggregates to hexanuclear species in toluene. In contrast, {[3-(C 3F 7),5-( t-Bu)Pz]Ag} 3, which has a bulky and relatively electron-rich pyrazolate, retains the trinuclear form even at low concentrations in toluene. Both {[3,5-(CF 3) 2Pz]Ag} 3 and {[3,5-( i-Pr) 2Pz]Ag} 3 adopt trinuclear structures in heptane at low concentrations. At higher concentrations, {[3,5-( i-Pr) 2Pz]Ag} 3 forms hexanuclear species. The aggregation-segregation points are rather sharp and are reminiscent of the all-or-none character of phase transitions. Remarkably, at higher concentrations, the aggregation states of these silver pyrazolates are similar to those expected based on solid-state data. 相似文献