Po Reaction Research Articles

Preparation and properties of difluorophosphino-derivatives of phosphorus(V) hydroxy-compounds

Phosphoric acid and other hydroxy-derivatives of phosphorus(V) react with S(PF2)2 to give difluorophosphino-esters. Tris(difluorophosphino) phosphate, PO(OPF2)3, and bis(difluorophosphino) monofluorophosphate, PFO(OPF2)2, have been prepared and characterised by n.m.r., mass, and vibrational spectroscopy. The reaction of PO(OPF2)3 with diborane is described. The formation and n.m.r. spectra of PO(OPF2)2Ph and PO(OPF2)Ph2 are also reported.

Free radical-induced oxidative degradation of polyacrylamide in aqueous solution

The oxidative main chain degradation of polyacrylamide initiated by ·OH radicals attacking the polymer in aqueous solution was studied. ·OH radicals were produced by irradiating dilute polymer solutions with high energy radiation. A bimolecular process (combination of PO 2 radicals) was found to be the rate determining step in the series of consecutive reactions leading to main-chain rupture. This was revealed from results obtained in pulse radiolysis studies using the light scattering detection method. Under the given experimental conditions, the number of radical sites per initial macromolecule exceeded unity with the consequence that intramolecular reactions of PO 2 radicals dominated intermolecular combinations. From both pulse radiolysis and continuous irradiations it was inferred that only a small fraction (about 1%) of the attacking ·OH radicals initiated main-chain scission.

Levels of 209Po and 211Po populated in one-neutron stripping and pickup from 210Po

Abstract Energy levels of 209 Po have been populated with the 210 Po(d, t) 209 Po and 210 Po(p, d) 209 Po reactions at bombarding energies of 17.0 and 17.8 MeV respectively. Fifteen levels were observed below 2.7 MeV of excitation. Energy levels of 211 Po were populated with the 210 Po(d, p) 211 Po reaction, also at 17.0 MeV. Thirty-five levels, almost all new, were observed below 3.9 MeV of excitation. Comparison of experimental angular distributions with DWBA calculations allowed l -value assignments and extraction of spectroscopic factors for many levels. In 209 Po the observed level structure is well described in terms of a simple particle-vibration coupling model. In 211 Po the level structure is more complex and the simple model is not adequate.

Die Phenoloxidase-Aktivität bei Gegenwart von H2O2, EDTA und Kupfer

Investigations performed with cryostat sections of the gut, spleen and lung of the rat have shown, that the substrate of PER H2O2 inhibits the PO activity in dependence of the concentration, and that obvious the PO substrate DOPA is no suitable H2-donator for the PER reaction. Therefore a false positive reaction by the PO proof is not to be expected. Copper sulfat does not influence the PO reaction, but it accelerates melanin formation, which causes an unspecific colouring of the tissue.

Vaporization of iron and phosphorus from iron-phosphorus melts in oxygen-bearing gas streams

Experiments have been made to demonstrate that when an oxygen-bearing gas is blown on the surface of iron-phosphorus melts, iron and phosphorus vaporize at rates enhanced by vapor-gas phase reactions. These findings are in accord with the theoretical predictions. The reaction mechanism considered is based on the concept of vaporization of phosphorus at the surface of iron as volatile PO and PO2, which then react with iron vapor and oxygen in the gas close to the surface of the melt. If powdered lime were present, as in the Q-BOP, a relatively stable calcium phosphate would form, thus bringing about dephosphrization. From the available thermodynamic data and reaction-equilibrium data, equilibrium constants have been derived for the reaction of PO and PO2 with liquid iron.

Radiative proton capture into 14N

Abstract The reactions 13C(p,γ1,2)14N and 13C(p, p', γ(3.09, 3.68, 3.85))13C have been studied for Ep = 3.0 to 18 MeV, covering the giant dipole resonance in 14N. Below Ep = 7.0 MeV resonances in the γ0 yield were found at Ep = 3.771 MeV (Γc.m.≦ 2keV), 4.53 (115 ± 10), 5.32 (48 ± 7) and 6.2 (1000 ± 150), corresponding to excitation energies of 11.049, 11.74, 12.485 and 13.3 MeV, respectively. From the angular distribution, Jπ = 2+, 3+ was established for the 11.049 MeV state, which is thus a newly found excited state of 14N. In all other cases cross correlations exist with states reported in other reactions. The 13.3 MeV state is thought to be part of the giant dipole resonance. Above 7 MeV bombarding energy the (p, γo) yield shows broad structure and the giant dipole resonance with two peaks at 22.5 and 23.0 MeV excitation energy. All peaks can be related to structure observed in the inverse photonuclear (γ, po) reaction. The inverted (p, γo) cross section exhausts 18 % of the classical dipole sum-rule between 12 and 24 MeV. Angular distributions indicate that most of the GDR up to 24 MeV is related to Jπ = 2− states, in accordance with theoretical predictions. The (p,γ1) yield to the Jπ = 0+, T = 1 state in 14N averages only 1 5 of the γ0 yield and no giant resonance structure is evident up to 24 MeV. The expectations for the T = 0 GDR based on the 2.31 MeV state are discussed. It is suggested that two narrow resonances seen at excitation energies of Ex = 23.7 MeV (Γc.m.≈ 500 keV) and 24.2 MeV (Γc.m.≈ 100 keV) are the lowest Jπ = 1−, T = 2 states in 14N.

THE PREPARATION AND IDENTIFICATION OF SOME INTERMETALLIC COMPOUNDS OF POLONIUM1

ABS>A micro technique for the preparation of intermetallic polonium compounds is described. Several polonides of the form MPo were prepared in this way and investigated by x-ray-powder diffraction; they include those of Be, Mg, Ca, Sr, Ba, Zn, Cd, Hg, and Pb. All these polonides, with the exception of Mg and Hg, were found to be isomorphous with the corresporiding compounds of S, Se, and Te. X-raydiffraction and crystal structure data are given. Reactions of Po with Ni, Cu, Ag, Au, C, Mo, Ta, and W are also described. (D.L.C.)

Relationship between strength and porosity for coal compacts

When powdered coal is compacted by subjecting it to high pressures it is found that the quality of the compact as measured by strength tests is, for a given batch of powder, a single valued function of the porosity of the compact. The shape of this strength-porosity curve cannot-be explained by treating the pores as if they only reduced the load bearing area available to withstand stresses in the compact. The form of the observed strength-porosity curves for compacts tested at right angles to the direction of compaction has been explained in terms of the development of contacts between particles with increasing compaction, and of the changing action of pores as stress magnifiers. A strength-porosity relationship of the form σ = (1 - pp)pp-1 has been deduced, where pp (rationalized porosity) is the ratio of the porosity of the compact to that of the pile of loose powder having no mechanical strength. It has been shown that this expression gives a good representation of the experimental data.