We compare molecular modeling results of two glassy polymer membranes and one rubbery polymer membrane with gas transport parameters and free-volume-related quantities from positronium annihilation. A simple geometric model reveals hole size distributions of asymmetric shape. Among glassy polymers, the distribution parameters show a good correlation with average hole sizes determined by positron annihilation lifetime spectroscopy. Higher permeability is measured in the glassy polymer with the higher mean value of the hole size distribution. The permselectivity of the membranes for permanent gases can be interpreted in terms of the distribution broadness via free-volume-controlled diffusion selectivity. A comparison with the rubbery polymer shows that the permeation behavior is not determined only by the free volume concentration. The thermal fluctuations of the polymer matrix play an important role for gas transport properties.

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AF demagnetization of thermoremanent magnetization (TRM) and saturation isothermal remanent magnetization (IRM(s)) are used to establish diagnostic criteria for primary TRM and for secondary magnetization in igneous rocks. In applying the approach to the interpretation of natural remanent magnetization (NRM), the demagnetization of IRM(s) documents the nature of the magnetic phases in the rock, while the demagnetization of the NRM gives information about the process of magnetization. The ratio of NRM : IRM (s) measures the efficiency of the magnetization process.

Paleomagnetic data from 231 samples from 31 sites in rocks of Upper Jurassic to Miocene age in Sarawak (Malaysian Borneo) reveal a trend of increasing counterclockwise (CCW) declination deflection with age. Six sites in Tertiary hypabyssal intrusions show 8° to 52° of CCW deflection. The intrusion deflected 52° CCW was K‐Ar dated at 26 m.y. (Upper Oligocene), while one deflected 22° CCW gives a 17 m. y. age (Lower Miocene). Three sites in the Upper Eocene to Miocene(?) Silantek Formation show an average 40° of CCW deflection. Prefolding directions, showing 90° of CCW deflection, are isolated in 4 sites (including two positive fold tests) in Upper Jurassic and Cretaceous rocks of the Bau Limestone and Pedawan Formations. A postfolding, Cenozoic remagnetization with an average of 60° of CCW deflection is found in five Bau Limestone sites. Three sites in the Upper Jurassic Kedadom Formation show an average of 50° of CCW deflection. CCW declination deflections found in Mesozoic and Cenozoic rocks as far as 400 km east and 150 km south of Sarawak, in Kalimantan (Indonesian Borneo), also fit the trend of deflection versus age. On the basis of the regional consistency of declination deflection versus age, along with geologic evidence the data are considered to be evidence of a regional (rather than a local block or distributed shear) rotation. The domain of CCW rotation extends into West Malaysia, suggesting that West Borneo and the Malay Peninsula may have been a stable block during the latest Cretaceous and Cenozoic. West Malaysia and Borneo may have had different histories in the rest of the Mesozoic. The data imply up to 108° CCW rotation of Borneo with respect to stable Eurasia, sometime during the Cretaceous and Cenozoic. Cenozoic rotation may also have occurred between Indochina and Borneo. The sense of rotation shown by the data does not support the “propagating extrusion tectonics” model for Cenozoic Southeast Asia.