A study of the reactions γp→ωp and γp→ωp and γp→ωΔ+

The differential and total corss sections and the decay density matrix elements have been measured for the reactions, γp→ωp and γp→ωΔ⁺ (1232) in the photon energy range 2.8 to 4.8 GeV. The total cross sections for ωΔ⁺ (1232) photo-production are found to be slightly larger than those for elastic ω photo-production in this energy range. The data are compared to the predictions of a theoretical model and the contributing exchange mechanics are discussed.     

Concerning phyltetralin : Synthesis of lignan aryltetralin isomers

The acid-catalyzed rearrangement of diaryl-dilactones, readily obtained by oxidation of ferulic acid derivatives, is examined as a synthesis route to aryltetralins. Two structures which have been proposed for the lignan, phyltetralin, are shown by synthesis of the two diastereomeric 1-veratryltetralins (3A) and (3B), to be untenable. Conidendrin has been converted to isolariciresinol tetramethyl ether (21) and comparison of empirical constants and spectra with those reported for phyltetralin strongly suggest that the lignan has the enantiomeric constitution (26).     

Appearance potential spectroscopy of layer materials

It has been shown that soft X-ray appearance potential spectroscopy (SXAPS) can be used as a probe of the conduction band density of states in several of the layer transition metal dichalcogenides, where the pronounced structure seen for TiS₂ agrees well with X-ray absorption data. In contrast, the complex structure seen in the SXAPS of pyrolytic graphite has previously been interpreted in terms of strong plasmon coupling. However, we find that the SXAP spectrum for vacuum cleaved pyrolytic graphite shows details not readily explicable by such an argument but which agree well with what would be expected on the basis of a conduction band self-convolution model. Further strong support for this interpretation is derived from XPS and SXAPS studies of the isostructural, isoelectronic boron nitride.     

Correlation effects and electron momentum distributions in the valence orbitals of ethylene

The non-coplanar symmetric (e, 2e) reaction has been applied to C₂H₄ at 1000-eV incident electron energy. An ion state at 27.4 eV separation en     

The non destructive determination of iodine in soils and biological materials by high energy gamma-photon activation

A non destructive high energy gamma photon activation technique has been developed for the determination of iodine in a wide range of natural materials. Results are presented and compared with those obtained by independent analytical techniques. Studies of the loss of iodine from soils on heating are also presented. The sensitivity and precision of the technique are discussed and its practical aspects described.     

Equilibrium encapsulation of polystyrene latex particles

We have performed a series of seeded styrene emulsion polymerizations in which the second stage of growth was initiated only after the second-stage monomer charge had achieved equilibrium saturation with the seed particles. The final particles were observed in the electron microscope by using two means of distinguishing between the first- and second-generation polymer: (a) butadiene tagging and osmium tetroxide staining coupled with ultramicrotomy and (b) tritiated-styrene tagging coupled with autoradiographic detection. We find that the first- and second-generation polymer chains are not uniformly mixed throughout the final latex product; rather, the second-generation polymer overcoats the seed polymer in a core–shell fashion. In order to explain these results, we present the viewpoint that monomer actually concentrates at the periphery of the swollen particle to form a monomer-encapsulated structure, rather than swelling the particle uniformly as has always been envisioned. We believe the encapsulation phenomena to be governed by the microscopic thermodynamic environment of the latex particles which has, in turn, a profound effect upon the conformational behavior of the long-chain polymer molecules as they interact with the particle–water interface.     

Analysis of the random configuration of the polycarbonate of diphenylol-2,2′-propane

The structure of the polycarbonate chain has been analyzed from the point of view of the spatial configurations it may assume. The carbonate group is certainly planar, and the trans,trans configuration probably is strongly preferred. Rotations about the aryloxygen bonds are subject to symmetric, twofold potentials. It follows that the molecule can be treated as a freely rotating chain consisting of a succession of virtual bonds 7.0 Å in length, joined at angles of ca. 112°. Calculations carried out on this basis yield 〈r²〉₀/M = 0.85 Ų/g-mole wt for the unperturbed random coil, in excellent agreement with the experimental results of Berry, Nomura, and Mayhan. The effect of occurrence of some of the carbonate groups in cis, trans configurations is investigated using more elaborate methods.