Normalized 87Sr86Sr by multiple collection and comparison to a standard

A system for precisely determining normalized ${}^{87}\text{Sr}{}^{86}\text{Sr}$ by comparing unknown to standard in a solid-source quadruple-collector mass spectrometer is outlined. This is made possible by a mathematical approximation in the data-reduction process.     

Effect of the solids retention time on the rate of biodegradation of organic compounds

The paper studies the effect of the solids retention time (SRT) on the rate of biodegradation of morpholine (M), sulfanilic acid (SA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA) in laboratory mixed culture systems, fed semicontinuously on a once-a-day feeding schedule. It has been found that the minimum values of SRT at which microorganisms degrading the above compounds were washed out from the cultivation systems were 3, 1, 1, and 20 days for M, SA, NTA, and EDTA systems, respectively. A critical value of SRT was defined as that below which the rate of substrate removal is lower than the rate of substrate application into the system. The critical values of SRT were found to be 8, 3, 2.5, and above 20 days for M, SA, NTA, and EDTA systems, respectively. In a range between the minimum and critical values of SRT the mixed culture system cannot give stable efficiency of a given compound removal and the effluent concentration can be expected to vary considerably. Above the critical value of SRT, every cultivation system has a potential capability of shock loading treatment.     

Asthenospheric parameters of dipping plate regions by magnetotelluric investigations

The multifrequency resolving capability of the electromagnetic surface impedance parameter, employed in magnetotelluric investigations, has been examined for an upper mantle model incorporating (1) a deep-seated lithosphere-asthenosphere boundary and (2) preferred orientations of olivine crystals in the lithosphere, usually associated with the subducting plate boundary zones. Numerical results display the quantitative errors in the resolution of various anisotropic and dipping plate conditions. It is found that (1) conductivity anisotropy, particularly with higher dips, causes a significant dispersion in the impedance values and higher resolving power, and (2) variations in the geometrical/physical parameters are reflected predominantly in the phase component of the surface impedance. The study has relevance to the understanding of the electrical nature of materials, its relationship with physical properties and associated geothermal and seismic activities in the dipping plate regions.     

Synchrotron radiation,an intense x-ray source for high pressure diffraction studies

The Wilson electron synchrotron at Cornell University has recently undergone modifications which enable it to produce a highly collimated X-ray beam of 10¹⁵ photons (s mrad. 10% bandwidth)^?1 in the range from 1 to 40 keV (12.4 to 0.31 Å wavelength). It is expected that a monochromatic beam produced from this source will have at least a hundred times the intensity of the X-rays from a rotating anode source. It is hoped that the use of a position-sensitive detector will improve the detection efficiency by another factor of a hundred over photographic film. If these improvements are realized, it should be possible to conduct real-time or nearly real-time diffraction experiments in the diamond anvil cell. The technique will be used to collect data for experiments in which slower data collecting would mean missing transient phenomena. The technique will also be useful for making studies during conditions that cause deterioration of the experimental apparatus such as graphitization of the diamonds or creep of the metal parts.