Transformation laws of the Newman-Penrose field variables

The transformation laws of all the Newman-Penrose gravitational field variables under the six parameter proper, orthochronous, Lorentz group are given. The method used here utilizes results obtained by Carmeli in his gauge theoretic formulation of the gravitational field equations.     

Experimental evaluation of analyte-furnace interactions using combined atomic absorption mass spectrometric techniques

A unique technique for simultaneous monitoring of thermally induced molecular and atomic species is used to investigate vaporization mechanisms for the rubidium analyte-tantalum furnace system used in atomic absorption analyses. The method involves combining atomic absorption and mass spectrometric techniques in order to achieve multiple probe capability; ultra-high vacuum techniques are incorporated in order to control the ambient environment. The results demonstrate the utility of this approach. Surface interactions are found to control the vaporization processes over a wide temperature range. At “low temperature” this surface interaction forms the oxide of the analyte, and at “high temperature” free rubidium atoms, which have been chemisorbed on the tantalum oxide surface, are desorbed as the tantalum oxide vaporizes.     

Development of assay,isotopic and trace actinide measurements on solid plutonium and uranium samples by high resolution gamma spectrometry

Journal of Radioanalytical and Nuclear Chemistry - The precise analysis of sub-gram quantities of actinide materials for regulatory and specification requirements currently relies on destructive,...     

EVALUATION OF PORPHYRIN CHARACTERISTICS REQUIRED FOR PHOTODYNAMIC THERAPY

The cytotoxicity (in the dark), phototoxicity (red light) and subcellular localization (using confocal laser scanning microscopy) were determined for 15 porphyrins (1-15) in C6 glioma cells. The partition coefficient in 2-octanol was also determined for each porphyrin at pH 7.4. The cytotoxicity increased with pi (log of partition coefficient) up to pi values of +2. The 7 porphyrins with cationic side chains exhibited a classical parabolic correlation between phototoxicity and pi, with maximal activity at a pi value of approximately 1.0. There was also a significant correlation between subcellular localization and degree of phototoxicity, with the three most photosensitive porphyrins all possessing cationic side chains, and all three localizing in mitochondria.     

Three-wave interactions between fast-ion modes in the National Spherical Torus Experiment

Simultaneous bursts of energetic particle mode (EPM) and toroidicity-induced Alfvén eigenmode (TAE) activity that correlate with significant fast-ion loss are observed in beam heated plasmas. Three-wave interactions between these modes are conclusively identified, indicating fixed phase relationships. This nonlinear coupling concentrates the energy of the TAEs into a toroidally localized perturbation frozen in the frame of a rigid, toroidally rotating structure formed by the EPMs. This redistribution of energy is significant because it will modify the effect of the TAEs on fast-ion loss.     

Investigating the vortex melting phenomenon in BSCCO crystals using magneto-optical imaging technique

Using a novel differential magneto-optical imaging technique we investigate the phenomenon of vortex lattice melting in crystals of Bi₂Sr₂CaCu₂O₈ (BSCCO). The images of melting reveal complex patterns in the formation and evolution of the vortex solid-liquid interface with varying field (H)/temperature (T). We believe that the complex melting patterns are due to a random distribution of material disorder/inhomogeneities across the sample, which create fluctuations in the local melting temperature or field value. To study the fluctuations in the local melting temperature/field, we have constructed maps of the melting landscape T _m(H, r), viz., the melting temperature (T _m) at a given location (r) in the sample at a given field (H). A study of these melting landscapes reveals an unexpected feature: the melting landscape is not fixed, but changes rather dramatically with varying field and temperature along the melting line. It is concluded that the changes in both the scale and shape of the landscape result from the competing contributions of different types of quenched disorder which have opposite effects on the local melting transition.     

Real‐time non‐invasive detection of inhalable particulates delivered into live mouse airways

Fine non‐biological particles small enough to be suspended in the air are continually inhaled as we breathe. These particles deposit on airway surfaces where they are either cleared by airway defences or can remain and affect lung health. Pollutant particles from vehicles, building processes and mineral and industrial dusts have the potential to cause both immediate and delayed health problems. Because of their small size, it has not been possible to non‐invasively examine how individual particles deposit on live airways, or to consider how they behave on the airway surface after deposition. In this study, synchrotron phase‐contrast X‐ray imaging (PCXI) has been utilized to detect and monitor individual particle deposition. The in vitro detectability of a range of potentially respirable particulates was first determined. Of the particulates tested, only asbestos, quarry dust, fibreglass and galena (lead sulfate) were visible in vitro. These particulates were then examined after delivery into the nasal airway of live anaesthetized mice; all were detectable in vivo but each exhibited different surface appearances and behaviour along the airway surface. The two fibrous particulates appeared as agglomerations enveloped by fluid, while the non‐fibrous particulates were present as individual particles. Synchrotron PCXI provides the unique ability to non‐invasively detect and track deposition of individual particulates in live mouse airways. With further refinement of particulate sizing and delivery techniques, PCXI should provide a novel approach for live animal monitoring of airway particulates relevant to lung health.     

Application of RTDF to particles with curved surfaces

The applicability of the ray tracing with diffraction on facets model is extended to particles with curved surfaces. This allows tests against T-matrix calculations for larger size parameters and modelling of light scattering by more realistic particle shapes, such as ice crystals with rounded edges.