The Host Galaxy and Central Engine of the Dwarf AGN POX 52

We present new multi-wavelength observations of the dwarf Seyfert 1 galaxy POX 52 in order to investigate the properties of the host galaxy and the active nucleus, and to examine the mass of its black hole, previously estimated to be ~ 10^5 M_sun. Hubble Space Telescope ACS/HRC images show that the host galaxy has a dwarf elliptical morphology (M_I = -18.4 mag, Sersic index n = 4.3) with no detected disk component or spiral structure, confirming previous results from ground-based imaging. X-ray observations from both Chandra and XMM show strong (factor of 2) variability over timescales as short as 500 s, as well as a dramatic decrease in the absorbing column density over a 9 month period. We attribute this change to a partial covering absorber, with a 94% covering fraction and N_H = 58^{+8.4}_{-9.2} * 10^21 cm^-2, that moved out of the line of sight in between the XMM and Chandra observations. Combining these data with observations from the VLA, Spitzer, and archival data from 2MASS and GALEX, we examine the spectral energy distribution (SED) of the active nucleus. Its shape is broadly similar to typical radio-quiet quasar SEDs, despite the very low bolometric luminosity of L_bol = 1.3 * 10^43 ergs/s. Finally, we compare black hole mass estimators including methods based on X-ray variability, and optical scaling relations using the broad H-beta line width and AGN continuum luminosity, finding a range of black hole mass from all methods to be M_bh = (2.2-4.2) * 10^5 M_sun, with an Eddington ratio of L_bol/L_edd = 0.2-0.5.Comment: 19 pages, 16 figures, accepted for publication in Ap

Linking dust emission to fundamental properties in galaxies: The low-metallicity picture

In this work, we aim at providing a consistent analysis of the dust properties from metal-poor to metal-rich environments by linking them to fundamental galactic parameters. We consider two samples of galaxies: the Dwarf Galaxy Survey (DGS) and KINGFISH, totalling 109 galaxies, spanning almost 2 dex in metallicity. We collect infrared (IR) to submillimetre (submm) data for both samples and present the complete data set for the DGS sample. We model the observed spectral energy distributions (SED) with a physically-motivated dust model to access the dust properties. Using a different SED model (modified blackbody), dust composition (amorphous carbon), or wavelength coverage at submm wavelengths results in differences in the dust mass estimate of a factor two to three, showing that this parameter is subject to non-negligible systematic modelling uncertainties. For eight galaxies in our sample, we find a rather small excess at 500 microns (< 1.5 sigma). We find that the dust SED of low-metallicity galaxies is broader and peaks at shorter wavelengths compared to more metal-rich systems, a sign of a clumpier medium in dwarf galaxies. The PAH mass fraction and the dust temperature distribution are found to be driven mostly by the specific star-formation rate, SSFR, with secondary effects from metallicity. The correlations between metallicity and dust mass or total-IR luminosity are direct consequences of the stellar mass-metallicity relation. The dust-to-stellar mass ratios of metal-rich sources follow the well-studied trend of decreasing ratio for decreasing SSFR. The relation is more complex for highly star-forming low-metallicity galaxies and depends on the chemical evolutionary stage of the source (i.e., gas-to-dust mass ratio). Dust growth processes in the ISM play a key role in the dust mass build-up with respect to the stellar content at high SSFR and low metallicity. (abridged)Comment: 44 pages (20 pages main body plus 5 Appendices), 11 figures, 9 tables, accepted for publication in A&

Nevada Test Site-Directed Research, Development, and Demonstration

The Nevada Test Site-Directed Research, Development, and Demonstration (SDRD) program completed a very successful year of research and development activities in FY 2005. Fifty new projects were selected for funding this year, and five FY 2004 projects were brought to conclusion. The total funds expended by the SDRD program were $5.4 million, for an average per project cost of just under$100,000. Two external audits of SDRD accounting practices were conducted in FY 2005. Both audits found the program's accounting practices consistent with the requirements of DOE Order 413.2A, and one included the observation that the NTS contractor ''did an exceptional job in planning and executing year-start activities.'' Highlights for the year included: the filing of 18 invention disclosures for intellectual property generated by FY 2005 projects; programmatic adoption of 17 FY 2004 SDRD-developed technologies; participation in the tri-lab Laboratory Directed Research and Development (LDRD) and SDRD program review that was broadly attended by NTS, NNSA, LDRD, and U.S. Department of Homeland Security representatives; peer reviews of all FY 2005 projects; and the successful completion of 55 R&D projects, as presented in this report

Operando chemical tomography of packed bed and membrane reactors for methane processing

Heterogeneous functional materials, like catalytic solids, batteries and fuel cells tend to usually possess complex structures where the 3D spatial distribution of the various components of these materials is rarely uniform. Such materials are known to change with time under operating conditions. In order to gain an insight into the structure-function relationships, it is essential to study them in situ with spatially-resolved techniques. The work presented in this thesis focuses on the development and application of synchrotron X-ray tomographic imaging methods to study various catalytic materials in real time and under real process conditions. The main X-ray tomographic imaging technique used in this study is X-ray diffraction computed tomography (XRD-CT) which couples powder diffraction with “pencil” beam computed tomography. Chapters 3 and 4 of this thesis outline some of the technical achievements accomplished in this work. More specifically, Chapter 3 outlines the development of a new data processing strategy used to remove line or “streak” artefacts generated in reconstructed XRD-CT images due to the presence of large crystallites in the sample; a common problem in XRD-CT measurements. Chapter 4 introduces a new data collection strategy, termed interlaced XRD-CT, which allows, post experiment, choice between temporal and spatial resolution. This data collection strategy can in principle be applied to all pencil beam CT techniques. The results from the first multi-length scale chemical imaging experiments of an unpromoted and a La-promoted Mn-Na-W/SiO2 catalyst for the oxidative coupling of methane are presented in Chapter 5. The spatially-resolved chemical signals obtained from these operando experiments provided new chemical information that can lead to the rational design of improved OCM catalysts. In Chapter 6, the results from, the first ever reported, XRD-CT experiments of working catalytic membrane reactors are presented. It is shown that the pertinent changes in the physicochemical state of these integrated reactor systems can be spatially-resolved. The results from Rietveld analysis of a 5D diffraction imaging (>106 diffraction patterns) redox experiment of a Ni-Pd/CeO2-ZrO2/Al2O3 catalyst and the first XRD-CT study of this catalyst during partial oxidation of methane are presented in Chapter 7

Poly(2-oxazoline)-based polymeric micelle platform for drug delivery

Polymeric micelles (PMs) have been extensively utilized as drug delivery platform. Particularly, potent hydrophobic small molecules were encapsulated in the PMs to alleviate toxicity issues and improve therapeutic outcomes. We attempt to provide detailed information on PMs for hydrophobic small molecules, such as the design of block copolymers (BCP) and current clinical outcomes from PMs. In particular, we aim to describe advanced analytical approaches for elucidating molecular interactions for effective solubilization. This dissertation includes a novel computer-aided strategy for rational design of PMbased delivery systems for poorly soluble drugs. We have developed novel descriptors of drug polymer complexes that were employed to build models to predict both drug loading efficiency (LE) and loading capacity (LC). These models were used for virtual screening of drug libraries and eight drugs for the experimental validation. Three putative true positive as well as three putative negative hits were confirmed (implying 75% prediction accuracy). The success of the computational strategy suggests its broad utility for rational design of drug delivery systems. This dissertation involves the study of poly(2-oxazoline) micelles (POx) for treatment of medulloblastoma. For patients with SHH-subgroup medulloblastoma, SHH-pathway inhibition may be more effective and less toxic than current non-targeted therapy. We successfully solubilized SHH-pathway inhibitor, vismodegib, in POx micelles (POx-vismo) and showed the PM formulation improved drug efficacy, demonstrated in the treatment of medulloblastoma animal model. Mechanistic studies revealed that POx-vismo decreased vismodegib binding to serum proteins and improved brain and tumor drug penetration without penetration of the nanoparticle carrier into the CNS. This dissertation also includes the development of novel poly(2-oxazoline)-based block copolymer with the aromatic heterocyclic side chains and demonstration of its application as a drug delivery platform. The copolymer was synthesized via the condensation of N,N dimethylbiguanide with the methyl ester side chain in poly(2-methoxycarboxyethyl-2-oxazoline) block (PMestOx). Successful encapsulation into these micelles has been demonstrated for several poorly soluble drugs. The capability of this new copolymer to solubilize a uniquely diverse set of active pharmaceutical ingredients suggests potential applications in drug delivery. In summary, poly(2-oxazoline)-based PM platforms are versatile drug delivery platform and exhibit the broad potential for ideal drug delivery of therapeutic small molecules.Doctor of Philosoph

Cumulative index to NASA Tech Briefs, 1970-1975

Tech briefs of technology derived from the research and development activities of the National Aeronautics and Space Administration are presented. Abstracts and indexes of subject, personal author, originating center, and tech brief number for the 1970-1975 tech briefs are presented

The 1974 NASA-ASEE summer faculty fellowship aeronautics and space research program

Research activities by participants in the fellowship program are documented, and include such topics as: (1) multispectral imagery for detecting southern pine beetle infestations; (2) trajectory optimization techniques for low thrust vehicles; (3) concentration characteristics of a fresnel solar strip reflection concentrator; (4) calaboration and reduction of video camera data; (5) fracture mechanics of Cer-Vit glass-ceramic; (6) space shuttle external propellant tank prelaunch heat transfer; (7) holographic interferometric fringes; and (8) atmospheric wind and stress profiles in a two-dimensional internal boundary layer