Retrospective source attribution for source-oriented sampling

Previous work successfully implemented a novel system that uses a single particle mass spectrometer to conditionally sample size-segregated, source-oriented particles from the ambient atmosphere in real-time. The underlying hypothesis is that the composition of individual particles is a metric of particle source and thus sampling particles based on composition should be synonymous with sampling based on source. System operation relies on real-time pattern recognition to control the actuation of different ChemVol samplers, where each ChemVol is associated with a unique composition signature. In the current work, a synthesis of data collected during these studies is used in retrospect to reconcile the actual source combinations contributing to the particles collected by each ChemVol. Source attribution is based on correlations between ChemVol sampling periods and coincident wind direction and temporal emissions patterns, coupled to knowledge of single particle composition and surrounding sources. Residential and commercial cooking, vehicular emissions, residential heating and highly processed regional background PM were identified as the major sources. Results show that real-time patterns in single particle mixing state correctly identified specific sources and that these sources were successfully separated into different ChemVols for both summer and winter seasons

Iterative detection and decoding for the four-rectangular-grain TDMR model

This thesis considers detection and error control coding for the two-dimensional magnetic recording (TDMR) channel modeled by the two-dimensional (2D) fourrectangular-grain model proposed by Kavcic, Huang et al. in 2010. This simple model captures the effects of different 2D grain sizes and shapes, as well as the TDMR grain overwrite effect: grains large enough to be written by successive bits retain the polarity of only the last bit written. We present a trellis for the channel possessing reasonable complexity while eliminating geometrically invalid states. A row-by-row BCJR detection algorithm is constructed based on the trellis that considers outputs from two rows at a time over two adjacent columns, thereby enabling consideration of more grain and data states than previously proposed algorithms that scan only two outputs at time. The proposed algorithm employs soft-decision feedback of grain states from previous rows to aid the estimation of current data bits and grain states. Simulation results using the same average coded bit density and serially concatenated convolutional code (SCCC) as a previous paper by Pan, Ryan, et al. show gains in user bits/grain of up to 6.7% over the previous work when no iteration is performed between the TDMR BCJR and iv the SCCC, and gains of up to 13.4% when the detector and the decoder iteratively exchange soft information

I. STUDIES IN THE STEVENS REARRANGEMENT. THE PREPARATION AND REARRANGEMENT OF QUATERNARY SALTS OF 4-KETO-1,2,3,4-TETRAHYDROISOQUINOLINE. II. STUDIES IN THE SYNTHESIS OF 4-KETO-1,2,3,4-TETRAHYDROISOQUINOLINE DERIVATIVES. III. THE CLEMMENSEN REDUCTION OF N-SUBSTITUTED PHTHALIMIDES.

Abstract not availabl

Nanoparticles, lung injury, and the role of oxidant stress.

The emergence of engineered nanoscale materials has provided significant advancements in electronic, biomedical, and material science applications. Both engineered nanoparticles and nanoparticles derived from combustion or incidental processes exhibit a range of physical and chemical properties that induce inflammation and oxidative stress in biological systems. Oxidative stress reflects the imbalance between the generation of reactive oxygen species and the biochemical mechanisms to detoxify and repair the damage resulting from reactive intermediates. This review examines current research on incidental and engineered nanoparticles in terms of their health effects on lungs and the mechanisms by which oxidative stress via physicochemical characteristics influences toxicity or biocompatibility. Although oxidative stress has generally been thought of as an adverse biological outcome, this review also briefly discusses some of the potential emerging technologies to use nanoparticle-induced oxidative stress to treat disease in a site-specific fashion

Toxicity of Al to Desulfovibrio desulfuricans

The toxicity of Al to Desulfovibrio desulfuricans G20 was assessed over a period of 8 weeks in a modified lactate C medium buffered at four initial pHs (5.0, 6.5, 7.2, and 8.3) and treated with five levels of added Al (0, 0.01, 0.1, 1.0, and 10 mM). At pH 5, cell population densities decreased significantly and any effect of Al was negligible compared to that of the pH. At pHs 6.5 and 7.2, the cell population densities increased by 30-fold during the first few days and then remained stable for soluble-Al concentrations of <5 × 10(−5) M. In treatments having total-Al concentrations of ≥1 mM, soluble-Al concentrations exceeded 5 × 10(−5) M and limited cell population growth substantially and proportionally. At pH 8.3, soluble-Al concentrations were below the 5 × 10(−5) M toxicity threshold and cell population density increases of 20- to 40-fold were observed. An apparent cell population response to added Al at pH 8.3 was attributed to the presence of large, spirilloidal bacteria (accounting for as much as 80% of the cells at the 10 mM added Al level). Calculations of soluble-Al speciation for the pH 6.5 and 7.2 treatments that showed Al toxicity suggested the possible presence of the Al(13)O(4)(OH)(24)(H(2)O)(12)(7+) “tridecamer” cation and an inverse correlation of the tridecamer concentration and the cell population density. Analysis by (27)Al nuclear magnetic resonance spectroscopy, however, yielded no evidence of this species in freshly prepared samples or those taken 800 days after inoculation. Exclusion of the tridecamer species from the aqueous speciation calculations at pHs 6.5 and 7.2 yielded inverse correlations of the neutral Al(OH)(3) and anionic Al(OH)(4)(−) monomeric species with cell population density, suggesting that one or both of these ions bear primary responsibility for the toxicity observed