1,394 research outputs found
Reduction Of Trace Quantities Of Chromium (vi) By Strong Acids
The chemical behavior of Cr(VI) at low concentrations (10-4 to 10-7 mol L-1) in several strong acids was studied using high specific activity 51Cr(VI) as a tracer. The speciation of the products from these systems was carried out by ion exchange chromatography with stepwise elution. The results show that trace quantities of Cr(VI), monitored by means of radiochromium (51Cr), are reduced in the presence of mineral acids such as perchloric, hydrochloric, hydrofluoric, sulfuric, nitric and trifluoromethanesulfonic acids, even in the absence of conventional reducing agents, producing different measureable Cr(III) species, depending on the acid anion. Detailed studies of the reduction of low concentrations of Cr(VI) with nitric acid have shown that the relative rate of reduction increases as the concentration of the acid increases or as the concentration of the Cr(VI) decreases.1515865Weeks, M.E., Leicester, H.M., (1968) Discovery of the Elements, 7th Ed., , American Chemical Society: EastonFeigl, F., (1943) J. Chem. Educ., 20, p. 240Westheimer, F.H., (1949) Chem. Rev., 45, p. 419Wiberg, K.B., (1965) Oxidation in Organic Chemistry, Part A, , Academic: New YorkCainelli, G., Cardillo, G., (1984) Chromium Oxidations in Organic Chemistry, , Springer-Verlag: BerlinDas, A.K., (2001) Oxid. Commun., 24, p. 321Beattie, J.K., Haight Jr., G.P., (1972) Prog. Inorg. Chem., 17, p. 93Fendorf, S., Wienlinga, B.W., Hansel, C.M., (2000) Int. Geol. Rev., 42, p. 691Smith, G.F., (1934) Ind. Eng. Chem. Anal. Edition, 6, p. 229Bobtelsky, M., Glasner, A., (1948) J. Chem. Soc., p. 1376Ho, W.-H., (1979) Proc. Natl. Sci. Counc. ROC, 4, p. 1Archundia, C., Collins, C.H., Collins, K.E., (1990) J. Radioanal. Nucl. Chem. Lett., 146, p. 49Archundia, C., Bonato, P.S., Lugo Rivera, J.F., Mascioli, L.C., Collins, C.H., Collins, K.E., (1993) Sci. Total Environ., 130-131, p. 231Archundia, C., Lugo Rivera, J.F., Collins, K.E., Collins, C.H., (1995) J. Radioanal. Nucl. Chem. Art., 195, p. 363Pezzin, S.H., Archundia, C., Collins, C.H., Collins, K.E., (1997) Radiochim. Acta, 77, p. 91Khan, Z., Hashmi, A.A., Din, K., (1998) Transition Met. Chem., 23, p. 147Pezzin, S.H., Collins, C.H., Archundia, C., Collins, K.E., (1998) J. Radioanal. Nucl. Chem., 236, p. 209Pezzin, S.H., Archundia, C., Collins, K.E., Collins, C.H., (2000) Czech. J. Phys., 50, p. 315Pezzin, S.H., Collins, C.H., Collins, K.E., (2000) Proceedings of the National Meeting on Nuclear Applications, , Rio de Janeiro, Brazil, CD-ROM, paper no. 61Pavel, J., Kliment, J., Stoerk, S., Suter, O., (1985) Fresenius Z. Anal. Chem., 321, p. 587Stollenwerk, K.G., Grove, D.B., (1985) J. Environ. Qual., 14, p. 386Gil, M., Escolar, D., Iza, N., Montero, J.L., (1986) Appl. Spectrosc., 40, p. 1156Tong, J.Y.P., King, E.L., (1960) J. Am. Chem. Soc., 82, p. 3805Espenson, J.H., King, E.L., (1963) J. Am. Chem. Soc., 85, p. 3328Khan, Z., Din, K., (2001) Indian J. Chem., 40 A, p. 528Haight Jr., G.P., Richardson, D.C., Coburn, N.H., (1964) Inorg. Chem., 3, p. 1777Espenson, J.H., (1964) J. Am. Chem. Soc., 86, p. 5101Pezzin, S.H., Collins, C.H., Collins, K.E., (2001) Radiochim. Acta, 89, p. 845House, D.A., (1994) Mechanisms of Inorganic and Organometallic Reactions, p. 97. , Twigg, M. V., ed.Plenum: New YorkSena, M.M., Scarminio, I.S., Collins, K.E., Collins, C.H., (2000) Talanta, 53, p. 453Cruywagen, J.J., Heyns, J.B.B., Rohwer, E.A., (1998) Polyhedron, 17, p. 1741Brito, F., Ascanio, J., Mateo, S., Hernandez, C., Araujo, L., Gili, P., MartinZarza, P., Mederos, A., (1997) Polyhedron, 16, p. 3835Nriagu, J.O., Nieboer, E., (1988) Chromium in the Natural and Human Environments, , Wiley: New YorkCollins, C.H., Pezzin, S.H., Lugo Rivera, J.F., Bonato, P.S., Windmöller, C., Archundia, C., Collins, K.E., (1997) J. Chromatogr. A, 789, p. 469Marques, M.J., Salvador, A., Morales-Rubio, A., De La Guardia, M., (2000) Fresenius. J. Anal. Chem., 367, p. 601Collins, K.E., Bonato, P.S., Archundia, C., De Queiroz, M.E.L.R., Collins, C.H., (1988) Chromatographia, 26, p. 160Collins, C.H., Collins, K.E., Ackerhalt, R.E., (1971) J. Radioanal. Chem., 8, p. 263De Andrade, J.C., Collins, K.E., (1981) Quim. Nova, 4, p. 89Gates, H.S., King, E.L., (1958) J. Am. Chem. Soc., 80, p. 5011Autenrieth, W., (1902) Ber. Deutsch. Chem. Ges., 35, p. 2057Krauss, H.L., Leder, M., Münster, G., (1963) Chem. Ber., 96, p. 3008Finholt, J.E., Ph.D. Thesis, Lawrence Radiation Laboratory Report UCRL-8879, University of California, Berkeley, 1960Collins, C.H., Lanças, F.M., (1982) Radiochem. Radioanal. Letters, 19, p. 117Jones, K.M., Bjerrum, J., (1965) Acta Chem. Scand., 19, p. 974Aggett, J., Udy, D.J., (1970) J. Inorg. Nucl. Chem., 32, p. 2802Chaabouni, M., Chausse, T., Pascal, J.L., Potier, J., (1980) J. Chem. Res. (S), 72Archundia, C., Collins, C.H., Collins, K.E., (1988) Proceedings of the Second General Congress on Nuclear Energy, 2, p. 415. , Rio de Janeiro, BrazilStünzi, H., Marty, W., (1983) Inorg. Chem., 22, p. 2145(1985) Chemical Analysis of Metals and Metal-Bearing Ores, , Annual Book of ASTM Standards, Section 3, Vol.03.05, American Society for Testing and MaterialsPhiladelphiaOttaway, J.M., Fell, G.S., (1986) Pure Appl. Chem., 58, p. 170
Soft-gluon effects in WW production at hadron colliders
We consider QCD radiative corrections to WW pair production in hadron
collisions. We perform a calculation that consistently combines next-to-leading
order predictions with soft-gluon resummation valid at small transverse momenta
ptWW of the WW pair. We present results for the ptWW distribution at the LHC up
to (almost) next-to-next-to-leading logarithmic accuracy, and study the effect
of resummation on the charged-lepton distributions. Soft-gluon effects are
typically mild, but they can be strongly enhanced when hard cuts are applied.
The relevant distributions are generally well described by the MC@NLO event
generator.Comment: 15 pages, 12 postscript figures. Error corrected in NLO plot for WW
transverse-mass distribution. Results unchange
Qubits from Number States and Bell Inequalities for Number Measurements
Bell inequalities for number measurements are derived via the observation
that the bits of the number indexing a number state are proper qubits.
Violations of these inequalities are obtained from the output state of the
nondegenerate optical parametric amplifier.Comment: revtex4, 7 pages, v2: results identical but extended presentation,
v3: published versio
Higher-Order QCD Corrections to Inclusive Particle Production in p anti-p Collisions
Inclusive single-particle production cross sections have been calculated
including higher-order QCD corrections. Transverse-momentum and rapidity
distributions are presented and the scale dependence is studied. The results
are compared with experimental data from the CERN S(p anti-p)S Collider and the
Fermilab Tevatron.Comment: 28 pages, [12 uuencoded PS figures, 3 available under request].
Preprint DESY 92-13
QCD Factorized Drell-Yan Cross Section at Large Transverse Momentum
We derive a new factorization formula in perturbative quantum chromodynamics
for the Drell-Yan massive lepton-pair cross section as a function of the
transverse momentum of the pair. When is much larger than the
pair's invariant mass , this factorization formula systematically resums the
logarithmic contributions of the type to all
orders in the strong coupling . When , our formula yields
the same Drell-Yan cross section as conventional fixed order QCD perturbation
theory. We show that resummation is important when the collision energy
is large enough and , and we argue that perturbative
expansions are more stable and reliable in terms of the modified factorization
formula.Comment: 36 pages, latex, including 16 figure
Differential Equations for Definition and Evaluation of Feynman Integrals
It is shown that every Feynman integral can be interpreted as Green function
of some linear differential operator with constant coefficients. This
definition is equivalent to usual one but needs no regularization and
application of -operation. It is argued that presented formalism is
convenient for practical calculations of Feynman integrals.Comment: pages, LaTEX, MSU-PHYS-HEP-Lu2/9
Virtual photon fragmentation functions
We introduce operator definitions for virtual photon fragmentation functions,
which are needed for reliable calculations of Drell-Yan transverse momentum
() distributions when is much larger than the invariant mass . We
derive the evolution equations for these fragmentation functions. We calculate
the leading order evolution kernels for partons to fragment into a unpolarized
as well as a polarized virtual photon. We find that fragmentation functions to
a longitudinally polarized virtual photon are most important at small , and
the fragmentation functions to a transversely polarized virtual photon dominate
the large region. We discuss the implications of this finding to the
J/ mesons' polarization at large transverse momentum.Comment: Latex, 19 pages including 6 figures. An error in the first version
has been corrected, and references update
Azimuthal correlation in DIS
We introduce the azimuthal correlation for the deep inelastic scattering
process. We present the QCD prediction to the level of next-to-leading log
resummation, matching to the fixed order prediction. We also estimate the
leading non-perturbative power correction. The observable is compared with the
energy-energy correlation in e+e- annihilation, on which it is modelled. The
effects of the resummation and of the leading power correction are both quite
large. It would therefore be particularly instructive to study this observable
experimentally.Comment: 33 pages, 4 figures, JHEP class included. One figure and some
clarifications adde
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