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Small-angle neutron scattering profiles from a concentrated (65 wt % ) polystyrene-polyieoprene block copolymer solution in dioctyl phthalate under shear were obtained both above and below the quiescent order-disorder transition (ODT). The ordered solution has a lamellar structure under quiescent conditions. The shear-induced structure was inferred from scattering measurements in two planes: the v-vxVv plane and the Vv-VXVU plane (v is the fluid velocity direction and Vv is the velocity gradient direction). Below the quiescent ODT, oscillatory shear produces lamellae that are aligned along the shearing surface, while steady shear results in a reorientation of the lamellae normals from the v-vxVv plane to the Vu-vxVv plane. Above the quiescent ODT, steady shear induces order above a critical shear rate. The resulting scattering anisotropy obtained at different temperatures obeys a universal scaling law, and the critical shear rate increases exponentially with temperature.

Measurements of the PVT behavior of compressed gaseous and liquid toluene are reported. Pressure versus temperature observations were made along paths of very nearly constant density (pseudolsochores) In the temperature range from about 348 to over 873 K and at pressures to about 35 MPa. Twenty-seven pseudolsochores were determined ranging In density from about 1.7 to near 9 mol/dm3.

Articles you may be interested inQuasielastic electron scattering from methane, methane-d4, methane-d2, ethylene, and 2-methylpropaneThe decay rate of spontaneous thermal fluctuations in methane has been determined from Rayleigh scattering experiments. Measurements have been made in a broad region about the critical point, along the coexistence .curve, the critical isochore, and an isotherm 0.8 K above the critical temperature. Values of thermal diffusivity obtained from the data are compared with other available data. In the immediate critical region the measured thermal diffusivity is compared with calculated thermal diffusivity values based on a recent prediction of the anomalous thermal conductivity of methane. The comparison involves assumptions concerning the scattered wave vector dependence of the decay rate in the critical region but involves no adjustable parameters. In addition, the critical isochore data are also fitted by other theoretically predicted forms for the decay rate to estimate parameters in these theories. Good agreement between measurement and prediction is found.Here kB is Boltzmann's constant, T is the absolute tem-

Two capacitive pressure gauges which have been used extensively in the study of liquid and solid helium are described. The first gauge, constructed of Be–Cu, has a sensitivity of Δp∼2×10−6 atm for pressures of 100 atm. It is highly stable, has essentially no hysteresis, and is affected very little by changes in temperature below 4.2 K. The second gauge is of nylon construction and is suitable for NMR or with paramagnetic salt thermometry. A detailed description of the construction and use of both gauges is given.