A method is developed for analyzing the outer part of the small-angle x-ray or neutron

No abstract

No abstract

The solutions, which contained from 1 to 2.5 hydroxide ions added per aluminum ion, were studied immediately after preparation and also in the final equilibrium condition. Aggregates present in the freshly prepared solutions probably have a characteristic platelet shape. Mention is made of the possible importance of these platelet-shaped aggregates to the structure of freshly precipitated aluminum hydroxide gel. Estimates of the size of the clusters present in the aged solutions were obtained in terms of the radius-of-gyration parameter. For solutions with OH/Al ion ratios between 1.5 and 2.25, the parameter had a constant value of 4.3 Å. This value is in good agreement with the calculated radius of gyration for the complex [Al13O4(OH)24(H2O)12]7+.

Experiments are reported in which (1) the resistivity has been measured as a function of the angle between the magnetic field direction and the current direction and as a function of the thickness in 82% Ni-18% Fe thin films, (2) the ferromagnetic resistance anisotropy in these films has been measured as a function of thickness, (3) the anisotropy in the fractional magnetoresistance has been measured as a function of thickness in these films, and (4) the anisotropy in the fractional magnetoresistance of films ranging in composition from 65% Ni-35% Fe to 92% Ni-8% Fe has been measured. The angular dependence of the resistivity agreed with theoretical predictions, provided suitable values are assumed for the mean free path and bulk resistivity of the films. The ferromagnetic resistance anisotropy appears to be independent of film thickness in the range from 75 to 2500 Å. The anisotropy in fractional magnetoresistance is lower than in bulk due to an abnormally high value for the resistivity of the zero magnetostrictive films studied. Nonzero magnetostrictive films also exhibit anomalies when the anisotropy in fractional magnetoresistance is compared with that in bulk material. A simple analytic expression relating these resistance anomalies to the magnetostriction parameter for the films is explained in terms of the magnetostriction of the films and the fact that they are attached to the substrate.

I n situ small-angle scattering measurements were made on a subbituminous coal during various stages of fluid extraction with tetrahydrofuran. The experiments not only showed the changes in the porosity due to fluid exposure, but also the pore filling characteristics of the fluid needed for extraction. Specifically, the experiments showed that the extensive micropore structure formed during fluid exposure at temperatures and pressures in the range of 380 °C and 4.5 MPa played a key role in the interaction of the fluid and coal matrix needed for a substantial extraction yield. Two distinct types of fluid penetration into the pore system were in evidence. One process involved the filling of the macropore structure. This process was observed at low temperature (120 °C) and high pressure, and did not cause appreciable swelling of the structure, but proved to be a reversible process when the fluid pressure was reduced. In contrast, the filling of the micropore system was accompanied by micropore dilation, which was irreversible at low temperatures.

No abstract

No abstract