PAH in the laboratory and interstellar space

The theory that polycyclic aromatic hydrocarbons (PAHs) are a constituent of the interstellar medium, and a source of the IR emission bands at 3.3, 6.2, 7.7, 8.6, and 11.3 microns is being studied using PAH containing acid insoluble residue of the Orgueil CI meteorite and coal tar. FTIR spectra of Orgueil PAH material that has undergone thermal treatment, and a solvent insoluble fraction of coal tar that has been exposed to hydrogen plasma are presented. The UV excided luminescence spectrum of a solvent soluble coal tar film is also shown. Comparison of the lab measurements with observations appears to support the interstellar PAH theory, and shows the process of dehydrogenation expected to take place in the interstellar medium

Ion bombardment experiments suggesting an origin for organic particles in pre-cometary and cometary ices

During the Giotto and Vega encounters with Comet Halley both organic particles called CHON and energetic ions were detected. The acceleration of ions to hundreds of keV in the vicinity of the bow shock and near the nucleus may be a demonstration of a situation occurring in the early solar system (perhaps during the T Tauri stage) that led to the formation of organic particles only now released. Utilizing a Van de Graaff accelerator and a target chamber having cryogenic and mass spectrometer capabilities, frozen gases were bombarded at 10 K with 175 keV protons with the result that fluffy solid material remains after sublimation of the ice. Initial experiments were carried out with a gas mixture in parts of 170 carbon monoxide, 170 argon, 25 water, 20 nitrogen, and 15 methane formulated to reflect an interstellar composition in experiments involving the freezing out of the products of a plasma. The plasma experiments resulted in a varnish-like film residue that exhibited luminescence when excited with ultraviolet radiation, while the ion bombardment created particulate material that was not luminescent

Continuous gas processing without bubbles using thin liquid film bioreactors containing biocomposite biocatalysts

Continuous microbial gas processing without bubbles is possible with thin liquid film, plug flow bioreactors. We have demonstrated that power input can be minimized by using a falling liquid film operating under laminar wavy flow conditions (Re \u3c200) in contact with highly concentrated living, non-growing microbes stabilized in a porous biocomposite biocatalyst. This composite materials approach to continuous gas processing can dramatically increase mass transfer rates \u3e100 fold compared to bubble aeration, decrease process volume, significantly decrease gas-liquid mass transfer energy input, decrease water use, and increase secreted product concentration. We have shown that this approach can also increase microbial specific activity for some organisms compared to microbes suspended in liquid media. Paper-based biocomposite biocatalysts provide a rough hydrophilic surface resulting in uniform ~300 μm thick falling liquid films. Paper roughness enhances gas-liquid-microbe mass transfer. This mass transfer enhancement has been simulated using a finite element (FEM) CFD model. The paper structure also functions as a separation device - the secreted products are released into the falling liquid film and continuously removed from the reactor. We are investigating biocomposite biocatalyst design and stabilization using a 0.05 m2 prototype cylindrical paper falling film bioreactor (FFBR). This approach can be used for continuous gas processing with either non-photosynthetic or photosynthetic microorganisms. Current experimental model systems we are investigating include Clostridium ljungdahlii OTA1 for absorbing CO from syn-gas, Methylomycrobium alkaliphilum 20Z for absorbing CH4 in air, and Chlamydomonas renhardtii for CO2 emissions. Critical to biocomposite biocatalyst design are generation of nanoporous coating microstructure, microbe adhesion to paper during film formation (which may include engineering the surface of the microbes), surviving osmotic shock in coating formulations, as well as desiccation tolerance to drying and prolonged dry storage. Spatially correlated Raman microspectroscopy and hyperspectral imaging techniques have been developed as a non-destructive method to monitor the distribution of residual water surrounding and within the cells. The distribution of vitrified residual water may contribute to desiccation resistance. Other types of thin liquid film reactors, such as a spinning disk bioreactor (SDBR), that enhance mass transfer by reducing liquid film thickness to \u3c100 μm with wave induced turbulent flow using centrifugal force (1000 x g) can be used in the future to further intensify continuous gas processing rates using biocomposite biocatalysts

Preliminary calibration results for the BATSE instrument on CGRO

Preliminary results pertaining to spectral reconstruction using Burst and Transient Source (BATSE) Large Area Detector measurements of solar flares are presented. The solar flare measurements are currently being used to fine tune the calibration of our data analysis software. The current status of the stability of spectral analysis, given the systematic errors present in burst location, are given. A brief description is given of enhancements to the input data for the atmospheric scattering algorithm that will be implemented in the data analysis software