Electroosmosis and electrochromatography in narrow bore packed capillaries.

Electroosmosis, the electrically induced flow of liquid, can be used as an alternative to pressure driven flow in liquid chromatography. Consideration of the physical nature of this type of flow suggests that less peak dispersion should result than with conventional flow. In addition theoretical considerations indicate that it should be possible to work with particles far smaller than those currently used in high performance liquid chromatography. This work describes the use of electroosmosis to propel electrolyte through narrow capillaries packed with typical chromatographic packing materials. The resistive heating generated by the passage of electric current through the medium dictates that this must be carried out in capillaries of less than 200 µm i.d.. The experimental methods used with such capillaries, including the production of packed capillaries are discussed. Experiments carried out in capillaries packed with particles as small as 1.5 µm in diameter demonstrate that adequate linear flow velocities can be obtained with particles which are too small for use in conventional chromatography due to pressure limitations. Measurements of the linear velocity of electroosmotic flow show that there is no evidence of a relationship between linear velocity and particle diameter, for particles ranging from 1.5 µm to 50 µm in diameter. The direct comparison of plate heights obtained using both pressure driven flow and electroosmotic flow shows’ that in the latter case considerably enhanced efficiencies are obtained. In some cases reduced plates heights as low as 0.7 have been achieved, providing strong evidence of a negligible contribution to the overall plate height from the van Deemter A-term. Using 1.5 µm diameter particles plate numbers of 300,000 have been obtained for an unretained analyte in a time of approximately 5 minutes. The implications of the results together with the performance limitations of electrically driven chromatography (electrochromatography) are discussed

Will Electric Cars Transform the U.S. Market

For the past forty years, United States Presidents have repeatedly called for a reduction in the country's dependence on fossil fuels in general and foreign oil specifically. Stronger efficiency standards and higher taxes on motor fuels are a step in this direction, but achieving even greater reductions in oil consumption will require changing the way Americans power their transportation system. Some officials advocate the electrification of the passenger vehicle fleet as a path to meeting this goal. The Obama administration has, for example, embraced a goal of having one million electric-powered vehicles on U.S. roads by 2015, while others proposed a medium-term goal where electric vehicles would consist of 20% of the passenger vehicle fleet by 2030—approximately 30 million electric vehicles. The technology itself is not in question—many of the global automobile companies are planning to sell plug-in hybrid electric vehicles (PHEVs) and/or battery electric vehicles (BEVs) by 2012. The key question is, will Americans buy them? The answer depends on four additional questions: 1. Is the cost of purchasing and operating an electric vehicle more or less expensive than the cost of a comparable conventional gasoline-powered vehicle? 2. Are the comparative costs likely to change over the next twenty years? 3. Do electric vehicles provide the same attributes as conventional cars, and if not, do the differences matter? 4. Will electric car owners be able to access the electricity needed to power their vehicles? This paper attempts to answer these four questions

Impact of inferred latent heating rates on predictions of convective storms

November 8, 1991.Also issued as author's thesis (M.S.) -- Colorado State University, 1991.Includes bibliographical references.A localized ordinary thunderstorm system occurred during the Convective Initiation and Downburst Experiment (CINDE) , in the Denver, Colorado area on 29-30 July 1987. The three-dimensional, nonhydrostatic version of the Regional Atmospheric Modeling System (RAMS) , developed at Colorado State University, was utilized in this case to investigate the impact of forced latent heating rates on short-range (12 hours or less) quantitative precipitation forecasts (QPFs). This was accomplished by using estimated convective precipitation rates , in a modified Kuo-type convective parameterization scheme, to determine the vertical-distribution of latent-heating rates. The inferred heating rates were then used, instead of the model predicted heating rates, to guide the model to a more desirable state. The sensitivity of the model to a variety of precipitation rates and the impact of the duration of simulation time are also examined. The 12 hour simulation with no forced heating failed to predict any precipitation in the northeast Colorado region. On the other hand, while the 24 hour simulation with no forced heating did predict precipitation in the northeast area of interest, the precipitation was positioned too far north of the observed precipitation area and the intensity was too small. In general, 12 hour simulations that used forced heating rates, for a one hour period during the simulation, produced the most improved precipitation forecasts. However, the results were extremely sensitive to the various precipitation rates used to obtain the forced heating rates, with weaker values having no impact at all and the strongest rates producing the most improved forecast.Sponsored by the National Aeronautics and Space Administration NGT-70153

Exploring the relationship between groundwater geochemical factors and denitrification potentials on a dairy farm in southeast Ireland

NOTICE: this is the author’s version of a work that was accepted for publication in the journal Ecological Engineering. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Ecological Engineering, volume 37, issue 9, September 2011, 1304-1313. DOI: 10.1016/j.ecoleng.2011.03.025peer-reviewedNitrate (NO3−) loss from agriculture to shallow groundwater and transferral to sensitive aquatic ecosystems is of global concern. Denitrifying bioreactor technology, where a solid carbon (C) reactive media intercepts contaminated groundwater, has been successfully used to convert NO3− to di-nitrogen (N2) gas. One of the challenges of groundwater remediation research is how to track denitrification potential spatially and temporally within reactive media and subsoil. First, using δ15N/δ18O isotopes, eight wells were divided into indicative transformational processes of ‘nitrification’ or ‘denitrification’ wells. Then, using N2/argon (Ar) ratios these wells were divided into ‘low denitrification potential’ or high denitrification potential’ categories. Secondly, using falling head tests, the saturated hydraulic conductivity (Ksat) in each well was estimated, creating two groups of ‘slow’ (0.06 m day−1) and ‘fast’ (0.13 m day−1) wells, respectively. Thirdly, two ‘low denitrification potential’ wells (one fast and one slow) with high NO3− concentration were amended with woodchip to enhance denitrification. Water samples were retrieved from all wells using a low flow syringe to avoid de-gassing and analysed for N2/Ar ratio using membrane inlet mass spectrometry. Results showed that there was good agreement between isotope and chemical (N2/Ar ratio and dissolved organic C (DOC)) and physio-chemical (dissolved oxygen, temperature, conductivity and pH) parameters. To explain the spatial and temporal distribution of NO3− and other parameters on site, the development of predictive models using the available datasets for this field site was examined for NO3−, Cl−, N2/Ar and DOC. Initial statistical analysis was directed towards the testing of the effect of woodchip amendment. The analysis was formulated as a repeated measures analysis of the factorial structure for treatment and time. Nitrate concentrations were related to Ksat and water level (p < 0.0001 and p = 0.02, respectively), but did not respond to woodchip addition (p = 0.09). This non-destructive technique allows elucidation of denitrification potential over time and could be used in denitrifying bioreactor technology to assess denitrification hotspots in reactive media, while developing a NO3− spatial and temporal predictive model for bioreactor site specific conditions

Successful Cessation Programs that Reduce Comorbidity May Explain Surprisingly Low Smoking Rates Among Hospitalized COVID-19 Patients

A recent, non-peer-reviewed meta-analysis suggests that smoking may reduce the risk of hospitalization with COVID-19 because the prevalence of smoking among hospitalized COVID-19 is less than that of the general population. However, there are alternative explanations for this phenomena based on (1) the failure to report, or accurately record, smoking history during emergency hospital admissions and (2) a pre-disposition to avoid smoking among COVID-19 patients with tobacco-related comorbidities (a type of “reverse” causation). For example, urine testing of hospitalized patients in Australia for cotinine showed that smokers were under-counted by 37% because incoming patients failed to inform staff about their smoking behavior. Face-to-face interviews can introduce bias into the responses to attitudinal and behavioral questions not present in the self-completion interviews typically used to measure smoking prevalence in the general population. Subjects in face-to-face interviews may be unwilling to admit socially undesirable behavior and attitudes under direct questioning. Reverse causation may also contribute to the difference between smoking prevalence in the COVID-19 and general population. Patients hospitalized with COVID-19 may be simply less prone to use tobacco than the general population. A potentially robust “reverse causation” hypothesis for reduced prevalence of smokers in the COVID-19 population is the enrichment of patients in that population with serious comorbidities that motivates them to quit smoking. We judge that this “smoking cessation” mechanism may account for a significant fraction of the reduced prevalence of smokers in the COVID-19 population. Testing this hypothesis will require a focused research program

Living in the Explore House: A Major and Career Exploration-Focused Residential Learning Community for Undecided Students

Scholarship on students who enter college without a declared major indicates that this population of students faces unique challenges (Anderson, 1985; Beal & Noel, 1980; Lewallen, 1993), but also may be more likely to persist to graduation and earn higher grades than those who enter college with a declared major (Lewallen, 1995). Based on undecided students’ needs for academic, career, and personal resources (Zarvell & Rigby, 1994), this article describes the implementation of a residential learning community (RLC) focused specifically on providing undecided students with in-hall programming and services related to academic major and career exploration, and provides implications for future implementation

Effects of Insect Populations on Seed Production of Sorghum vulgare (Pers.)

Entomolog