All-chalcogenide glass omnidirectional photonic band gap variable infrared filters

Cataloged from PDF version of article.We report on the design, fabrication, and characterization of spatially variable infrared photonic band gap filter that consists of thermally evaporated, high refractive index contrast, amorphous chalcogenide glass multilayers. Due to graded thickness structure, the filter exhibits a position dependent stop band and a cavity mode ranging from 1.8 to 3.4 μm wavelengths. Reflection measurements on the variable filter agree well with theoretical calculations. These results pave the way to low-loss infrared mirrors, filters, spectral imaging, and miniaturized spectrometers at infrared region. © 2009 American Institute of Physics

Soot nucleation and growth in weakly-buoyant laminar jet diffusion flames

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76524/1/AIAA-1994-428-986.pd

Carbon monoxide and soot emissions from liquid-fueled buoyant turbulent diffusion flames

Carbon monoxide concentrations, soot concentrations, and mixture fractions were measured in the fuel-lean (overfire) region of liquid-fueled buoyant turbulent diffusion flames burning in still air. Pool-fire configurations were studied with the liquids burning from horizontal round wicks, considering both sooting (toluene, benzene, n-heptane, and isopropanol) and nonsooting (methanol and ethanol) fuels. Flame heights and characteristic residence times also were measured, both for the turbulent flames and at the normal smoke point (for the sooting fuels). Carbon monoxide and soot generation factors (mass of CO or soot emitted per unit mass of fuel carbon burned) were uniform throughout the overfire region and were relatively independent of flame residence times (which were generally an order of magnitude longer than the normal smoke point residence times of the sooting fuels). Processes of carbon monoxide and soot emission for the nonalcohols are closely related, based on the good correlation between their emission factors: 0.37 kg CO/per kg soot with a standard deviation of 0.09. However, nonsooting methanol and ethanol/air flames still emitted low levels of CO so that there is a component of CO emissions that is not associated with soot.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/29094/1/0000130.pd

Structure of overfire soot in buoyant turbulent diffusion flames at long residence times

The structure of soot was investigated within the fuel-lean (overfire) region of overventilated buoyant turbulent diffusion flames burning in still air. The study was limited to the long residence time regime where characteristic flame residence times are roughly more than an order of magnitude longer than the laminar smoke point residence time and soot generation factors (the mass of soot emitted per unit mass of fuel carbon burned) are relatively independent of flame residence times. Both gaseous and liquid fuels were used to provide a range of H/C ratios (1-2.7) and fuel types (alkynes, alkenes, alkanes, aromatics, and alcohols) as follows: toluene, acetylene, benzene, propylene, ethylene, n-heptane, propane, and isopropanol. Measurements included transmission electron microscopy to find primary particle diameters, the number of primary particles per aggregate and aggregate geometrical and fractal dimensions. The results show that the structure of soot varies with fuel type but is relatively independent of both position in the overfire region and flame residence time for the long residence time regime. Mean primary particle diameters were 30-51 nm and the mean number of primary particles per aggregate were 255-552, with the larger values associated with the more heavily sooting fuels. Aggregate fractal dimensions, however, were less dependent on fuel type, only varying in the range 1.70-1.79. The structure measurements are used to estimate the optical properties of overfire soot, based on a recent approximate theory for polydisperse aggregates, finding significant differences between aggregate and Rayleigh scattering properties in the visible and near-infrared portions of the spectrum, even though the primary particles are well within the Rayleigh scattering regime.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/30068/1/0000438.pd

Structure of soot-containing laminar jet diffusion flames

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76650/1/AIAA-1993-708-697.pd

All-chalcogenide glass omnidirectional photonic band gap variable infrared filters

We report on the design, fabrication, and characterization of spatially variable infrared photonic band gap filter that consists of thermally evaporated, high refractive index contrast, amorphous chalcogenide glass multilayers. Due to graded thickness structure, the filter exhibits a position dependent stop band and a cavity mode ranging from 1.8 to 3.4 μm wavelengths. Reflection measurements on the variable filter agree well with theoretical calculations. These results pave the way to low-loss infrared mirrors, filters, spectral imaging, and miniaturized spectrometers at infrared region. © 2009 American Institute of Physics

All-chalcogenide variable infrared filter

We present the design, fabrication, characterization of spatially variable infrared filter and a demonstration of the filter as a simple infrared spectrometer. A varying photonic band gap filter which consists of thermally evaporated, high refractive index contrast amorphous chalcogenide glass multilayers, makes the structure suitable to be used as spectrometer. Due to graded thickness structure, the filter exhibits a position dependent stop band and a cavity mode ranging from 2 to 8 μm wavelengths. It is demonstrated that the filter can be used to detect absorption peaks of common gases in the cavity mode range of the filter. © 2009 SPIE

Cocaine- and amphetamine-regulated transcript promoter regulated by nicotine in nerve growth factor-treated PC12 cells

Nicotine and cocaine- and amphetamine-regulated transcripts (CART) have several overlapping functions, such as the regulation of reward, feeding behavior, stress response, and anxiety. Previous studies showed that nicotine regulates CART expression in various brain regions. However, the molecular mechanisms underlying this regulation are not known. This study investigated the regulatory effect of nicotine on promoter activity of the CART gene in PC12 cells, which were differentiated into a neuronal phenotype by nerve growth factor (NGF) treatment. Two vectors containing reporter genes (Gaussia luciferase or mCherry) and the 1,140-bp upstream of the transcriptional start site of the mouse CART gene are used to analyze the CART promoter activity. Transient transfection of PC12 cells with either vector displayed strong promoter activity in both undifferentiated and differentiated PC12 cells. CART promoter activity in the PC12 cell line is increased by forskolin or NGF treatment. In differentiated PC12 cells, exposure to 50 nM nicotine for 6 h increased CART promoter activity. However, treatment with higher nicotine doses for 6 h and treatment with all nicotine doses for 24 h showed no effect. A nicotine concentration of 50 nM is comparable to brain nicotine levels experienced by chronic smokers over long periods of time. Taken together, these data indicate that nicotine may exert some of its actions through the regulation of CART transcription in the brain

A Small Angle Scattering Sensor System for the Characterization of Combustion Generated Particulate

One of the critical issues for the US space program is fire safety of the space station and future launch vehicles. A detailed understanding of the scattering signatures of particulate is essential for the development of a false alarm free fire detection system. This paper describes advanced optical instrumentation developed and applied for fire detection. The system is being designed to determine four important physical properties of disperse fractal aggregates and particulates including size distribution, number density, refractive indices, and fractal dimension. Combustion generated particulate are the primary detection target; however, in order to discriminate from other particulate, non-combustion generated particles should also be characterized. The angular scattering signature is measured and analyzed using two photon optical laser scattering. The Rayleigh-Debye-Gans (R-D-G) scattering theory for disperse fractal aggregates is utilized. The system consists of a pulsed laser module, detection module and data acquisition system and software to analyze the signals. The theory and applications are described