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71.
Recent measurements of differential and elastic cross-sections, slope parameters and ratios of the real and imaginary parts
of the forward scattering amplitudes for pion-proton elastic scattering at 200 GeV/c have been fitted by using a simple Regge
pole model with phenomenological residue functions. The computed results for total cross-sections have also been compared
with the experimental data. 相似文献
72.
The modulational instability of ion acoustic waves is studied in the presence of a dc magnetic field, taking the ion temperature into account. It is well known that the instability sets in for wave numbers exceeding 1.47 kD when there is no magnetic field and the ion temperature is negligible. The instability behaviour, however, changes drastically when either the magnetic field is switched on or the ion temperature becomes important or both. In general three different regions emerge wherein the waves becomes modulationally unstable. The relative sizes of these regions change as the magnetic field, the angle of propagation and the ion temperature are varied. 相似文献
73.
Substitution reactions take place following the photonic excitation of aqueous K4M(CN)8 (where M = Mo or W) in the presence of 1,10-phenanthroline and 2,2bipyridyl. Changes in absorbance with time show that the overall reaction is dependent on photochemical activation of potassium octacyanomolybdate(IV) and -tungstate(IV). The species [K2Mo(CN)4(OH)2(phen)], [K2W(CN)4(OH)2(phen)], [K2Mo(CN)4(OH)2(bipy)] and [K2W(CN)4(OH)2(bipy)] exist in solution. The final photosubstitution products [Mo(OH)3(CN)(phen)2] · 2H2O], [Mo(OH)3(CN)(bipy)2] · 3H2O, [W(OH)3(CN)(phen)2] · 2H2O and [W(OH)3(CN)(bipy)2] · H2O have been isolated in the solid state. Their IR spectra have been discussed. The quantum yield of the photosubstitution reactions has been determined and its variation with change of concentration of the complex as well as the H+ ion concentration has been studied. 相似文献
74.
Michael Koch Mahmood Saleem Gernot Krammer 《Particle & Particle Systems Characterization》2007,24(6):431-439
The measurement of a distributed property is frequently encountered in engineering applications. The impact of a possible measurement error on the measured distribution is described and two methods to account for such an error are detailed: A Fourier transform based deconvolution procedure and a moment based deconvolution approach via kernel estimators are presented. The deconvolution methods can be used in many particle characterization and process applications where particle features or properties are commonly presented in a distributed form. In the current instance, these methods are carefully explored by using artificially generated data and applied to experimental data obtained from filter cake thickness measurements. 相似文献
75.
Eann A. Patterson Erwin Hack Philippe Brailly Richard L. Burguete Qasim Saleem Thorsten Siebert Rachel A. Tomlinson Maurice P. Whelan 《Optics and Lasers in Engineering》2007,45(5):550
The design and testing of a reference material for the calibration of optical systems for strain measurement is described, together with the design and testing of a standardized test material that allows the evaluation and assessment of fitness for purpose of the most sophisticated optical system for strain measurement. A classification system for the steps in the measurement process is also proposed and allows the development of a unified approach to diagnostic testing of components or sub-systems in an optical system for strain measurement based on any optical technique. The results described arise from a European study known as SPOTS whose objectives were to begin to fill the gap caused by a lack of standards. 相似文献
76.
Zakir Murtaza Leah Tolosa Peter Harms Joseph R. Lakowicz 《Journal of fluorescence》2002,12(2):187-192
We describe a new approach to optical sensing of glucose based on the competitive interactions between a ruthenium metal ligand complex, a boronic acid derivative and glucose. The metal-ligand complex [Ru(2,2-bipyridine)2(5,6-dihydroxy-1,10-phenanthroline)](PF6)2 at pH 8 forms a reversible complex with 2-toluylboronic acid or 2-methoxyphenyl boronic acid. Complexation is accompanied by a several-fold increase in the luminescent intensity of the ruthenium complex. Addition of glucose results in decreased luminescent intensity, which appears to be the result of decreased binding between the metal-ligand complex and the boronic acid. Ruthenium metal-ligand complexes are convenient for optical sensing because their long luminescent decay times allow lifetime-based sensing with simple instrumentation. 相似文献
77.
Jayasimhadri M Moorthy LR Saleem SA Ravikumar RV 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,64(4):939-944
Optical absorption, luminescence and lifetime measurements of Sm(3+)-doped alkali fluorophosphate glasses with molar compositions of 50(NaPO(3))(6)+10TeO(2)+20AlF(3)+19RF+1Sm(2)O(3) (R=Li, Na and K) are described. The variation of optical properties with glass composition plays a dominant role in the determination of efficient laser materials. From the experimental oscillator strengths of f-f electric dipole transitions, the phenomenological Judd-Ofelt parameters have been evaluated and are used to evaluate radiative parameters such as radiative transition probabilities (A(R)), branching ratios (beta(R)), lifetimes (tau(R)) and integrated absorption cross-section (sigma(a)) for various excited levels. The predicted values of tau(R) and beta(R) from the (4)G(5/2) excited level to its lower levels are compared with the experimentally measured values. Stimulated emission cross-sections (sigma(e)) were also determined for (4)G(5/2)-->(6)H(J) (J=5/2, 7/2, 9/2 and 11/2) emission transitions. From the emission transitions of Sm(3+) in these alkali tellurofluorophosphate glasses certain potential laser transitions have been identified. 相似文献
78.
Ammar R Bean A Besson D Davis R Kwak N Zhao X Anderson S Frolov VV Kubota Y Lee SJ Mahapatra R O'Neill JJ Poling R Riehle T Smith A Stepaniak CJ Urheim J Ahmed S Alam MS Athar SB Jian L Ling L Saleem M Timm S Wappler F Anastassov A Duboscq JE Eckhart E Gan KK Gwon C Hart T Honscheid K Hufnagel D Kagan H Kass R Pedlar TK Schwarthoff H Thayer JB von Toerne E Zoeller MM Richichi SJ Severini H Skubic P Undrus A Chen S Fast J Hinson JW Lee J Miller DH Shibata EI Shipsey IP Pavlunin V 《Physical review letters》2001,86(7):1167-1170
Using data recorded with the CLEO II and CLEO II.V detector configurations at the Cornell Electron Storage Rings, we report the first observation and mass measurement of the Sigma(*+)(c) charmed baryon, and an updated measurement of the mass of the Sigma(+)(c) baryon. We find M(Sigma(*+)(c))-M(Lambda(+)(c)) = (231.0+/-1.1+/-2.0) MeV, and M(Sigma(+)(c))-M(Lambda(+)(c)) = (166.4+/-0.2+/-0.3) MeV, where the errors are statistical and systematic, respectively. 相似文献
79.
Porphyrin-metal complexes are potentially useful to catalyze redox reactions, which convert toxic and biologically recalcitrant
compounds to compounds that are less toxic and more amenable to biotreatment. Porphyrins, in the absence of proteins as in
ligninases, peroxidases, and oxidases, are potentially more robust than enzymes and microbial cultures in the treatment of
inhibitory substances.
2,4,6-Trichlorophenol was used as a model compound for chlorinated phenols and as a substrate for various porphyrin-metal
complexes acting as oxidation catalysts. t-Butyl hydroperoxide was the oxidizing agent. TCP was shown to be at least partially
dechlorinated and the aromatic ring broken in reaction products. All porphyrins exhibited saturation kinetics with regard
to the initial TCP concentration in reaction mixtures. Electron-withdrawing substituents on the porphyrins were observed to
increase stability of the catalysts to inactivating ring-centered oxidation. 相似文献
80.
Joseph R. Lakowicz Zakir Murtaza Wayne E. Jones Jr. Kihan Kim Henryk Szmacinski 《Journal of fluorescence》1996,6(4):245-249
We report the first observation of polarized emission from a rhenium-phenanthroline complex, Re(CO)3(phen)Cl. Highly luminescent rhenium complexes are known, with quantum yields near 0.5 and lifetimes in excess of 10 s. The detection of polarized emission suggests the use of rhenium complexes as probes of the hydrodynamics of large macromolecular complexes and for use in fluorescence polarization immunoassays with gated detection. 相似文献