NGR study of pyrrhotites obtained in coal hydroliquefaction

Iron Mössbauer spectroscopy has been performed on 38 residues of hydroliquefaction of the French bituminous Freyming coal, without and with added iron based catalysts. 56 to 94 % of the area of each spectrum was occupied by 2, 3, 4 or 5 sextets of Fe_1?xS, either at 295 K or at 78 K or at 4 K. Values of H at 295 K are proposed: 299, 283, 268, 254, 242 and 228 kOe, ±3 kOe, associated with δ(α-Fe)=0.72±0.02 mm/s. The vacancies responsible for the values of H are likely to be randomly distributed. The best accuracy on the relative intensities cannot ensure a precise determination of the overall stoichiometry, so that a better knowledge of the samples is given by the distribution of the Fe sites.     

Determination of the angular and energy dependence of hard constituent scattering from π0 pair events at the CERN intersecting storage rings

We present data on proton-proton collisions, obtained at the CERN Intersecting Storage Rings, in which two roughly back-to-back π⁰'s of high transverse momentum (p_T) were produced. The angular distribution of the dipion axis relative to the collision axis is found to be independent of both the effective mass m of the dipion system and the centre-of-mass energy √s of the proton-proton collision. The cross-sections $\text{d}\text{σ}\text{d}\text{m}$ at the values of √s satisfy a scaling law of the form $\text{d}\text{σ}\text{d}\text{m}\text{=}\text{G(x)}\text{m}{}^{\mathrm{n}}\text{,}\text{where}\text{x = m(π}{}^0\text{, π}{}^0\text{)//trs}\text{and}\text{n = 6.5 ± 0.5}$. We show from our data that the leading π⁰ carries most of the momentum of the scattered parton. Given this fact, the axis of the dipion system follows closely the direction of the scattered constituents, and we exploit this to determine the angular dependence of the hard-scattering subprocess. We also compare our data with the lowest order QCD predictions using structure functions as determined in deep-inelastic scattering and fragmentation functions from electron-positron annihilation.     

High pT π0 production from αα and αp collisions at the CERN ISR

The invariant cross sections for π⁰ meson production in alpha—alpha and alpha—proton collisions at the ISR were meas- ured up to transverse momenta of $\text{7}\text{GeV}\text{c}$ and $\text{8}\text{GeV}\text{c}$, respectively. These measurements are compared with π⁰ production in pp collisions at the same values of $\text{s}\text{/}$nucleon, and the variation of the nuclear A-dependence with p_T is determined.     

A Method for Obtaining Exact Solutions to Partial Differential Equations with Variable Coefficients

This paper describes techniques that can be used to transform PDEs with variable coefficients into equations with constant coefficients. The techniques are illustrated by calculating shear flows over quite general surfaces, by solving the signaling problem for diffusive processes in inhomogeneous materials, and by solving the signaling problem for acoustical waves when the sound speed varies with distance. The techniques may also be used to solve equations governing processes in inhomogeneous, anisotropic materials.     

The general solution of the vacuum einstein equation in the limit of strong gravity

The general solution to the strong coupling limit of the vacuum Einstein field equations is obtained. This limit is related to the theory of symmetric spaces.On leave from the Department of Mathematics, Monash University, Clayton, Victoria, 3168, Australia.On leave from F.A.M.A.F., Laprida 854, University of Cordoba, 5000 Cordoba, Argentina.On leave from the Physics Department, Jamestown Community College, Jamestown, N.Y. 14701.     

Silicon-29 and carbon-13 n.m.r. studies of organosilicon chemistry. VII—trimethylsilylated silicates

Silicon-29 n.m.r. was used to study the products from trimethylsilylation of minerals. Chemical shifts are reported for four model compounds, viz. the monomer, dimer, linear trimer (from natrolite) and cyclic tetramer (from laumontite). Information is then obtained from the products of trimethylsilylation of the anhydrous calcium silicates wollastonite and pseudo-wollastonite. In the latter case it is shown that the principal products are the four model compounds, and percentage yields are obtained for these.     

Temperature dependence of the thermal conductivity for tellurium dioxide

The thermal conductivity of tellurium dioxide is reported as a function of temperature. At 77K, the thermal conductivity is 0.09 W/cm-K and it decreases approximately as the inverse of the temperature to a value of 0.02 W/cm-K at 300K. The anisotropy between the a- and c-axes is less than 20% over the entire experimental temperature range, with the a-axis more conductive than the c-axis. By making some simplifying assumptions, the phonon mean free paths and relaxation times are deduced.     

A radical diophantine equation

All solutions in positive integers x, yz of the diophantine equation $\text{x}{}^{\mathrm{<mtext>1</mtext><mtext>m</mtext>}}\text{+ y}{}^{\mathrm{<mtext>1</mtext><mtext>n</mtext>}}\text{= z}{}^{\mathrm{<mtext>1</mtext><mtext>r</mtext>}}$ are determined, where m, n, r are given positive integers. The proof makes use of a simple criterion for the irreducibility of the polynomial xⁿ ? a over the rationals, where a is a positive rational.     

Cationated cyclopropanes as reaction intermediates in mass spectra: an earlier incarnation of ion-neutral complexes

The appearance a decade ago of the concept of ion-neutral complexes as intermediates in unimolecular decompositions constituted a major advance in mechanistic interpretation of mass spectra. The concept, however, was not new; it goes back to the introduction of the cationated cyclopropane in the mid-1950s. Its development did not occur via a smooth progression; rather, its history bridges a sharp discontinuity. The early workers, in a curious historical quirk, failed to generalize on the idea beyond complexes in which the neutral component is cyclopropane or a closely related species. Hence it took an independent rediscovery of the concept to usher in the rapid growth and wide application that characterize its present stage of development.