Category: Uncategorized

J. Houston Miller, Greg B.Clarke,  Hilary Melroy, Lesley Ott and  Emily Wilson Steel

GeoCarbon:Towards an operational global carbon observing system; 24 Sep. 2013; Geneva; Switzerland

In a collaboration between NASA GSFC and GWU, a low-cost, surface instrument is being developed that can continuously monitor key carbon cycle gases in the atmospheric column: carbon dioxide (CO₂) and methane (CH₄). The instrument is based on a miniaturized, laser heterodyne radiometer (LHR) using near infrared (NIR) telecom lasers. Despite relatively weak absorption line strengths in this spectral region, spectrallyresolved atmospheric column absorptions for these two molecules fall in the range of 60-80% and thus sensitive and precise measurements of column concentrations are possible. In the last year, the instrument was deployed for field measurements at Park Falls, Wisconsin; Castle Airport near Atwater, California; and at the NOAA Mauna Loa Observatory in Hawaii. For each subsequent campaign, improvement in the figures of merit for the instrument has been observed. In the latest work the absorbance noise is approaching 0.002 optical density (OD) noise on a 1.8 OD signal. An overview of the measurement campaigns and the data retrieval algorithm for the calculation of column concentrations will be presented. For light transmission through the atmosphere, it is necessary to account for variation of pressure, temperature, composition, and refractive index through the atmosphere that are all functions of latitude, longitude, time of day, altitude, etc. For temperature, pressure, and humidity profiles with altitude we use the Modern-Era Retrospective Analysis for Research and Applications (MERRA) data. Spectral simulation is accomplished by integrating short-path segments along the trajectory using the SpecSyn spectral simulation suite developed at GW. Column concentrations are extracted by minimizing residuals between observed and modeled spectrum using the Nelder-Mead simplex algorithm. We will also present an assessment of uncertainty in the reported concentrations from assumptions made in the meteorological data, LHR instrument and tracker noise, and radio frequency bandwidth and describe additional future goals in instrument development and deployment target

J. HoustonMiller, Jennifer D. Herdman, Candace D.O.Green, and Erin M.Webster

Proceedings of the Combustion Institute, 2013, 34, 3669-3675

Carbon, 49, Issue 15, December 2011, Pages 5298-5311

The predictions of “soot” concentrations from numerical simulations for nitrogen-diluted, ethylene/air flames are compared with laser-induced incandescence and Raman spectra observed from samples thermophoretically extracted using a rapid insertion technique. In some flame regions, the Raman spectra were obscured by intense, radiation that appeared to peak in the near infrared spectral region. There is a good agreement between spatial profiles of this ex situ laser-induced incandescence (ES-LII) and the “traditional” in situ laser-induced incandescence (IS-LII). Raman signatures were observed from low in the flame and extended into the upper flame regions. The spectra consisted of overlapping bands between 1000 and 2000 cm⁻¹ dominated by the “G” band, near ≈1580 cm⁻¹, and the “D” band in the upper 1300 cm⁻¹ range. Several routines are explored to deconvolve the data including 3- and 5-band models, as well as a 2-band Breit–Wigner–Fano (BWF) model. Because the Raman signals were observed at heights below those where in situ LII was observed, we postulate that these signals may be attributable to smaller particles. The results suggest that the observed Raman signals are attributable to particulate with modest (≈1 nm) crystallite sizes. This observation is discussed in the context of current models for nascent particle formation.

US8063373 B2

This invention relates to a compact cavity ring down spectrometer for detection and measurement of trace species in a sample gas using a tunable solid-state continuous-wave mid-infrared PPLN OPO laser or a tunable low-power solid-state continuous wave near-infrared diode laser with an algorithm for reducing the periodic noise in the voltage decay signal which subjects the data to cluster analysis or by averaging of the interquartile range of the data.

Applied Optics Vol. 48, Issue 4, pp. 695-703 (2009)

A portable cavity ringdown spectroscopy (CRDS) apparatus was used to detect effluents from small test fires in the Fire Emulator/Detector Evaluator (FE/DE) and a small room in the Building Fire and Research Laboratory at the National Institute of Standards and Technology (NIST). The output from two lasers is combined to detect four combustion gases, CO, CO2, HCN, and C2H2, near simultaneously using CRDS. The goal of this work was to demonstrate the feasibility of using a CRDS sensor as a fire detector. Fire effluents were extracted from several test facilities and measurements of CO, CO2, HCN, and C2H2 were obtained every 25–30 s. In the FE/DE test, peak concentrations of the gases from smoldering paper were 420 parts in 106 (ppm) CO, 1600 ppm CO2, 530 parts in 109 (ppb) HCN, and 440 ppb C2H2. Peak gas concentrations from the small room were 270 ppm CO, 2100 ppm CO2, and 310 ppb C2H2.

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WO2006060171 A2

Embodiments of the invention include additional compositions and related methods and devices for the use of phage-nanoparticle assemblies. Embodiments of the invention include compositions, methods and devices related to phage-nanoparticle assemblies and their use in a variety of methods including detection methods, in vitro and in vivo diagnostic methods, direct and/or indirect therapeutic methods, or combinations thereof. Phage-nanoparticle assemblies of the invention comprise a plurality of nanoparticles complexed with one or more phage particles to form a phage-nanoparticle assembly. In certain aspects, the phage-­nanoparticle assembly may also include other agents, including but not limited to organizing agents and/or therapeutic agents.

ExcimersPCI30_1381_2005-1im2phh

US5252060 A

An optical method for monitoring the products of combustion, particularly for the detection of upset conditions in the incineration of hazardous waste, is disclosed. On-line detection of upsets is extremely important to avoid sending untreated waste out the stack plume and to avoid the formation of hazardous products of incomplete combustion, such as dioxins. Small hydrocarbons are the strongest candidates for in situ monitoring of combustion efficiency. The combustion is monitored via infrared absorption using tunable diode lasers (TDLs).

Combust. Sci: and Tech, 1987, Vol. 52, pp.139-149

Abstract: Methyl radicals have been detected in a laminar methane/air diffusion flame via an application of the scavenger probe technique. In these experiments, a quartz microprobe was modified such that iodine vapor was pumped from a storage side arm into the inside tip of the probe. Sampled methyl radicals react quantitatively with iodine to produce methyl iodide, which was detected by a mass spectrometer. The resulting quantitative profiles are compared to profiles of stable intermediate hydrocarbons which have been observed in this flame, as well as to profile signals which are due to methyl radical ionization by laser radiation. The concentrations of methyl are combined with velocity and temperature data to calculate the net rate of chemical reactions of methyl radical in the flame. The use of methyl radical concentration and rate data to estimate the concentrations of other reactive species is discussed.

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