7,877 research outputs found
Photosensitized oxidation of unsaturated polymers
The photosensitized oxidation or singlet oxygenation of unsaturated hydrocarbon polymers and of their model compounds was reviewed. Emphasis was on cis and trans forms of 1,4-polyisoprene, 1,4-polybutadiene and 1,2-poly(1,4-hexadiene), and on 1,4-poly(2,3-dimethyl-1,3-butadiene). The microstructural changes which occur in these polymers on reaction with O2-1 in solution were investigated by infrared H-1 and C-13 NMR spectroscopy. The polymers were shown to yield allylic hydroperoxides with shifted double bonds according to the ene mechanism established for simple olefins. The photosensitized oxidation of the above unsaturated polymer exhibited zero order kinetics, the relative rates paralleling the reactivities of the corresponding simple olefins towards O2-1
Vacuum ultraviolet irradiation of polybutadiene final report
Vacuum ultraviolet irradiation of polybutadien
Photochemistry of unsaturated polymers
Radiation induced photochemical reactions in polyisoprene and polybutadiene thin films including microstructural change
Simultaneous Least Squares Treatment of Statistical and Systematic Uncertainties
We present a least squares method for estimating parameters from measurements
of event yields in the presence of background and crossfeed. We adopt a unified
approach to incorporating the statistical and systematic uncertainties on the
experimental measurements input to the fit. We demonstrate this method with a
fit for absolute hadronic D meson branching fractions, measured in e+e- ->
\psi(3770) -> D\bar D$ transitions.Comment: 9 pages, 2 figures; minor clarifications, one figure adde
Shot noise in the interacting resonance level model
The shot noise power and the Fano factor of a spinless resonant level model
is calculated. The Coulomb interaction which in this model acts between the
lead electron and the impurity is considered in the first order approximation.
The logarithmic divergencies which appeared in the expressions for shot noise
and the transport current are removed by renormalization group analysis. It is
shown that Keldysh technique gives an adequate description of perturbation
theory results. By passing to the bosonized form of the resonance model it is
proven that in the strong interaction limit the tunnelling becomes irrelevant
and decreases.Comment: 4 pages, 2 figure
Interleukin 2 and stimulator lymphoblastoid cells will induce human thymocytes to bind and kill K562 targets.
Human thymocytes cultured in the presence of IL-2 and an irradiated B cell line became cytotoxic to K562 target cells. Thymocytes cultured alone or with only IL-2 exhibited almost no killing, but thymocytes cultured in the presence of stimulator cells alone exhibited low levels of cytotoxic activity. Removal of Fc gamma receptor-bearing cells from the activated thymocyte population almost completely abolished the binding and lytic activity. Separation of thymocytes into Fc microns+ and Fc microns-cells before culturing with IL-2 and stimulator cells revealed that only the Fc microns+ subpopulation developed into K562 killer cells. These findings indicate that modulation of Fc microns to Fc gamma receptors on the thymocyte cell surface is part of the maturation process of this particular subset of cytotoxic cells. Morphologically, most of the activated Fc gamma+ K562-binding cells were large, granulated lymphocytes. Only very few of the round, nongranulated small thymocytes were bound to K562 target cells
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