Fourier-Transform Infrared Absorption Spectroscopy in Binary Hydrocarbon-Alcohol Single Droplet Evaporation

Broadband absorption spectroscopy, by way of FTIR, was used to investigate the vapor cloud of a single millimeter sized liquid droplet suspended by a syringe as it evaporates at standard conditions. Single beam data were collected every 8 seconds resulting in a time-resolved record. Species concentrations were tracked using their resonant absorption peaks and correlated with a multidimensional numerical model. The numerical model combined a Gaussian beam transmission through a temporally changing spherical vapor cloud with radial concentration gradients, informed by the D² law and interpreted using the Abel transform. There was fair agreement with temporal evaporation trends for single component runs. Multicomponent experiments of ethanol and isooctane showed synergistic blending effects and preferential evaporation of ethanol. Droplets were also suspended by a thermocouple to track the droplet temperature over time as they were subject to evaporative cooling. This work is the foundation of a basic technique for collecting useful data to inform a complex transport problem.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by Hindawi Publishing Corporation. The published article can be found at: http://www.hindawi.com/journals/jspec

Leveraging Case Study Research: A Mechanism to Measure Teaching Effectiveness

This article shares findings from a descriptive, multiple case study assessing graduate outcomes 2.5 years after the completion of a teacher education program. Case study was used as an alternative to value-added measures to holistically examine complex attributes of effective teaching. Mixed methods data collection included graduate and supervisor surveys, self and supervisor evaluation of skills and dispositions, interviews, and classroom observations. Results indicated participants effectively applied the knowledge, skills, and dispositions the program was designed to achieve in the areas of Learner and Learning, Content, Instructional Practice, and Professional Responsibility. Three major recommendations emerged: 1) the necessity to develop established proficiency levels for new teachers related to diverse learners, 2) the need for shared responsibility of outcomes and targeted induction support, and 3) support for supervisor evaluation as a viable mechanism for education program accountability of teaching effectiveness of graduates

Extraordinary Late-Time Infrared Emission of Type IIn Supernovae

Near-Infrared (NIR) observations are presented for five Type IIn supernovae (SN 1995N, SN 1997ab, SN 1998S, SN 1999Z, and SN 1999el) that exhibit strong infrared excesses at late times (t >= 100 d). H- and K-band emission from these objects is dominated by a continuum that rises toward longer wavelengths. The data are interpreted as thermal emission from dust, probably situated in a pre-existing circumstellar nebula. The IR luminosities implied by single temperature blackbody fits are quite large,> 10^(41 - 42) erg s^-1, and the emission evolves slowly, lasting for years after maximum light. For SN 1995N, the integrated energy release via IR dust emission was 0.5 -- 1 * 10^50 erg. A number of dust heating scenarios are considered, the most likely being an infrared echo poweredby X-ray and UV emissions from the shock interaction with a dense circumstellar medium.Comment: 14 Pages, 3 Figures, Accecpted for publication in The Astrophysical Journa

The Quest for the Missing Dust: II -- Two Orders of Magnitude of Evolution in the Dust-to-Gas Ratio Resolved Within Local Group Galaxies

We explore evolution in the dust-to-gas ratio with density within four well-resolved Local Group galaxies - the LMC, SMC, M31, and M33. We do this using new ${\it Herschel}$ maps, which restore extended emission that was missed by previous ${\it Herschel}$ reductions. This improved data allows us to probe the dust-to-gas ratio across 2.5 orders of magnitude in ISM surface density. We find significant evolution in the dust-to-gas ratio, with dust-to-gas varying with density within each galaxy by up to a factor 22.4. We explore several possible reasons for this, and our favored explanation is dust grain growth in denser regions of ISM. We find that the evolution of the dust-to-gas ratio with ISM surface density is very similar between M31 and M33, despite their large differences in mass, metallicity, and star formation rate; conversely, we find M33 and the LMC to have very different dust-to-gas evolution profiles, despite their close similarity in those properties. Our dust-to-gas ratios address previous disagreement between UV- and FIR-based dust-to-gas estimates for the Magellanic Clouds, removing the disagreement for the LMC, and considerably reducing it for the SMC - with our new dust-to-gas measurements being factors of 2.4 and 2.0 greater than the previous far-infrared estimates, respectively. We also observe that the dust-to-gas ratio appears to fall at the highest densities for the LMC, M31, and M33; this is unlikely to be an actual physical phenomenon, and we posit that it may be due to a combined effect of dark gas, and changing dust mass opacity.Comment: Accepted for publication in the Astrophysical Journa

Development and characterization of 16 microsatellite markers for the Louisiana pine snake, Pituophis ruthveni, and two congeners of conservation concern

We isolated and characterized 16 microsatellite loci from the Louisiana pine snake, Pituophis ruthveni. Loci were screened in 24 individuals from locations throughout its distribution in Louisiana and Texas. The number of alleles per locus ranged from 4 to 12, observed heterozygosity ranged from 0.200 to 0.875, and the probability of identity ranged from 0.043 to 0.298. We examined cross-species amplification at these loci in P. catenifer (bullsnakes and gopher snakes) and P. melanoleucus (pine snakes). These new markers provide tools for examining the conservation genetics of this species complex. Louisiana pine snakes face numerous threats: population densities are extremely low and their natural habitat has been severely altered and fragmented. In southern Canada, P. catenifer is at the northern extreme of its range and limited by the availability of suitable over-wintering sites. Hence, for these two species reduction of heterozygosity, potential for inbreeding, and increased effects of genetic drift are all of considerable conservation concern

Detection of CO and Dust Emission in Near-Infrared Spectra of SN 1998S

Near-infrared spectra (0.95 -- 2.4 micron) of the peculiar Type IIn supernova 1998S in NGC 3877 from 95 to 355 days after maximum light are presented. K-band data taken at days 95 and 225 show the presence of the first overtone of CO emission near 2.3 micron, which is gone by day 355. An apparent extended blue wing on the CO profile in the day 95 spectrum could indicate a large CO expansion velocity (~2000 -- 3000 km/s). This is the third detection of infrared CO emission in nearly as many Type II supernovae studied, implying that molecule formation may be fairly common in Type II events, and that the early formation of molecules in SN 1987A may be typical rather than exceptional. Multi-peak hydrogen and helium lines suggest that SN 1998S is interacting with a circumstellar disk, and the fading of the red side of this profile with time is suggestive of dust formation in the ejecta, perhaps induced by CO cooling. Continuum emission that rises towards longer wavelengths (J -> K) is seen after day 225 with an estimated near-infrared luminosity >~ 10^40 erg/s. This may be related to the near-infrared excesses seen in a number of other supernovae. If this continuum is due to free-free emission, it requires an exceptionally shallow density profile. On the other hand, the shape of the continuum is well fit by a 1200 +- 150 K blackbody spectrum possibly due to thermal emission from dust. Interestingly, we observe a similar 1200 K blackbody-like, near-infrared continuum in SN 1997ab, another Type IIn supernova at an even later post-maximum epoch (day 1064+). A number of dust emission scenarios are discussed, and we conclude that the NIR dust continuum is likely powered by the interaction of SN 1998S with the circumstellar medium.Comment: 38 Pages, 12 Figures, Submitted to The Astronomical Journa

Investigation of the LTC fuel performance index for oxygenated reference fuel blends

A new metric for ranking the suitability of fuels in LTC engines was recently introduced, based on the fraction of potential fuel savings achieved in the FTP-75 light-duty vehicle driving cycle. In the current study, this LTC fuel performance index was calculated computationally and analyzed for a number of fuel blends comprised of n-heptane, isooctane, toluene, and ethanol in various combinations and ratios corresponding to octane numbers from 0 to 100. In order to calculate the LTC index for each fuel, computational driving cycle simulations were first performed using a typical light-duty passenger vehicle, providing pairs of engine speed and load points. Separately, for each fuel blend considered, single-zone naturally aspirated HCCI engine simulations with a compression ratio of 9.5 were performed in order to determine the operating envelopes. These results were combined to determine the varying improvement in fuel economy offered by fuels, forming the basis for the LTC fuel index. The resulting fuel performance indices ranged from 36.4 for neat n-heptane (PRF0) to 9.20 for a three-component blend of n-heptane, isooctane, and ethanol (ERF1). For the chosen engine and chosen conditions, in general lower-octane fuels performed better, resulting in higher LTC fuel index values; however, the fuel performance index correlated poorly with octane rating for less-reactive, higher-octane fuels.Keywords: HCCI engines, Low-temperature combustion, Gasoline, Octane numberKeywords: HCCI engines, Low-temperature combustion, Gasoline, Octane numbe

A Novel Fuel Performance Index for Low-Temperature Combustion Engines Based on Operating Envelopes in Light-Duty Driving Cycle Simulations

Low-temperature combustion (LTC) engine concepts such as homogeneous charge compression ignition (HCCI) offer the potential of improved efficiency and reduced emissions of NOₓ and particulates. However, engines can only successfully operate in HCCI mode for limited operating ranges that vary depending on the fuel composition. Unfortunately, traditional ratings such as octane number poorly predict the autoignition behavior of fuels in such engine modes, and metrics recently proposed for HCCI engines have areas of improvement when wide ranges of fuels are considered. In this study, a new index for ranking fuel suitability for LTC engines was defined, based on the fraction of potential fuel savings achieved in the FTP-75 light-duty vehicle driving cycle. Driving cycle simulations were performed using a typical light-duty passenger vehicle, providing pairs of engine speed and load points. Separately, single-zone naturally aspirated HCCI engine simulations were performed for a variety of fuels in order to determine the operating envelopes for each. These results were combined to determine the varying improvement in fuel economy offered by fuels, forming the basis for a fuel performance index. Results showed that, in general, lower octane fuels performed better, resulting in higher LTC fuel index values; however, octane number alone did not predict fuel performance