Experiments in general chemistry

The investigations described here in are concerned with several problems. The original investigation dealt with a common qualitative test for the presence of cobalt ion. The test involves the use of alcoholic ammonium thiocyanate which results in the formation of the unstable blue complexion Co(SCN)4

Master of Science

thesisSerum creatinine concentrations and estimated glomerular filtration rates (eGFR) are widely used for the evaluation of renal function. The Jaffe and enzymatic methods are the most common methods for creatinine measurement. The Jaffe method is commonly less expensive than enzymatic methods but may be more susceptible to interferences. Significant savings could be obtained if populations could be identified where the interference rate of the Jaffe method is acceptably low. The study objective was to compare creatinine and corresponding eGFR results from representative Jaffe and enzymatic creatinine methods in an outpatient population and determine the prevalence and magnitude of differences. This study analyzed 543 unique, randomly selected, outpatient samples. Samples were analyzed using both the Jaffe and enzymatic creatinine methods using an Abbott Architect c8000. eGFRs were calculated using the CKD-EPI and MDRD equations. Orthogonal (Deming) regression showed no significant difference between the two assays. The slope was 1.006 (95% CI: 0.998, 1.103) and the intercept was -0.005 (95% CI: -0.015, 0.006). The average difference (bias) was -0.007 mg/dL. The Bland- Altman limits of agreement (LOA) for the creatinine differences were -0.139 and 0.136 mg/dL. Of the CKD-EPI eGFR discrepancies, 3.1% resulted in a reclassification at the 60 mL/min/1.73m2 decision limit. The difference between the predicted and actual CKDEPI discordance at the 60 mL/min/1.73m2 decision limit was not statistically significant (χ! ! = -0.13, p=0.89). Of the MDRD eGFR discrepancies, 4.8% resulted in a iv reclassification at the 60 mL/min/1.73m2 decision limit. The difference between the predicted and actual MDRD discordance at the 60 mL/min/1.73m2 decision limit was not statistically significant (χ! ! = 0.31, p=0.76). Discrepancies in the CKD-EPI and MDRD eGFRs based on the Jaffe method did not result in a statistically significant increase in disease reclassifications at the 60 mL/min/1.73m2 decision limit in an outpatient population. The number of discordant eGFR results slightly varied by what discordance criteria was used. An equal number of discordances were observed with the MDRD and CKD-EPI equations when eGFR were based upon measurement error (217 of 543). When discordance criteria was based upon observed differences (Bland-Altman), the MDRD equation showed slightly more discordances (26 of 543) compared to the CKD-EPI (21 of 543). Studies are needed to characterize the relative rate of interference in additional populations

There is No Place Like Home

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Characterization of low thermal conductivity PAN-based carbon fibers

The microstructure and surface chemistry of eight low thermal conductivity (LTC) PAN-based carbon fibers were determined and compared with PAN-based fibers heat treated to higher temperatures. Based on wide-angle x ray diffraction, the LTC PAN fibers all appear to have a similar turbostratic structure with large 002 d-spacings, small crystallite sizes, and moderate preferred orientation. Limited small-angle x ray scattering (SAXS) results indicate that, with the exception of LTC fibers made by BASF, the LTC fibers do not have well developed pores. Transmission electron microscopy shows that the texture of the two LTC PAN-based fibers studied (Amoco T350/23X and /25X) consists of multiple sets of parallel, wavy, bent layers that interweave with each other forming a complex three dimensional network oriented randomly around the fiber axis. X ray photoelectron spectroscopy (XPS) analysis finds correlations between heat treated temperatures and the surface composition chemistry of the carbon fiber samples

Near field performance of staged diffusers in shallow water

This work was performed by John H. Trowbridge as part of his masters thesis in the M.I.T. Dept. of Civil Engineering, 1979.Submerged diffusers are commonly used to dilute condenser cooling water from coastal power plants. A staged diffuser, in which the diffuser centerline is perpendicular to shore and the nozzles are direc- ted essentially offshore, is often used at sites where there is a long- shore, reversing current. Because of the symmetry of this design, dilution is improved by a longshore current in either direction, and the diffuser's position perpendicular to shore allows it to intercept a crossflow effectively. The performance of a staged diffuser in shallow water of constant depth has been analysed previously by treating the diffuser as a continuously distributed line source of momentum (Almquist and Stolzen- bach, 1976). This theory has been reviewed and extended to consider the case of a sloping bottom and to compute the external (entrainment) flow field set up by the diffuser. In these analyses the important parameters are the gross diffuser dimensions, including total flow rate, discharge velocity, water depth and diffuser length. Length scales are on the order of one diffuser length, and the characteristics of the individual jets are assumed to be insignificant in describing diffuser performance at this level. A more detailed analysis of staged diffuser performance in the near field is useful if one wishes to describe the temperatures and shear stresses experienced by organisms that are entrained into the diffuser plume. Length scales in this problem are on the order of the port spacing, and characteristics of the individual jets are very important at this level. Relevant diffuser dimensions are discharge velocity, port diameter D , port spacing, port elevation h, water depth H, and discharge orientation. A description of the near field at this level has been obtained by solving for the trajectories, velocities, temperatures and flow rates of individual jets. Boundary layer approximations are made similar to those used in the classical analysis of free turbulent jets, and the analysis includes the effects of shallow water, the flowfield set up by adjacent jets, and an ambient current. Theoretical predictions are compared with the results of an experimental program. The analysis is then used to evaluate different diffuser designs from the stand- point of temperature and shear stress exposure of entrained organisms

LADEE Satellite Modeling and Simulation Development

As human activity on and around the Moon increases, so does the likelihood that our actions will have an impact on its atmosphere. The Lunar Atmosphere and Dust Environment Explorer (LADEE), a NASA satellite scheduled to launch in 2013, will orbit the Moon collecting composition, density, and time variability data to characterize the current state of the lunar atmosphere. LADEE will also test the concept of the "Modular Common Bus" spacecraft architecture, an effort to reduce both development time and cost by designing reusable, modular components for use in multiple missions with similar requirements. An important aspect of this design strategy is to both simulate the spacecraft and develop the flight code in Simulink, a block diagram-style programming language that allows easy algorithm visualization and performance testing. Before flight code can be tested, however, a realistic simulation of the satellite and its dynamics must be generated and validated. This includes all of the satellite control system components such as actuators used for force and torque generation and sensors used for inertial orientation reference. My primary responsibilities have included designing, integrating, and testing models for the LADEE thrusters, reaction wheels, star trackers, and rate gyroscopes

Whose Little Girl Are You

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