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Toward an Optimal Position for IVC Filters: Computational Modeling of the Impact of Renal Vein Inflow

Description: The purpose of this report is to evaluate the hemodynamic effects of renal vein inflow and filter position on unoccluded and partially occluded IVC filters using three-dimensional computational fluid dynamics. Three-dimensional models of the TrapEase and Gunther Celect IVC filters, spherical thrombi, and an IVC with renal veins were constructed. Hemodynamics of steady-state flow was examined for unoccluded and partially occluded TrapEase and Gunther Celect IVC filters in varying proximity to the renal veins. Flow past the unoccluded filters demonstrated minimal disruption. Natural regions of stagnant/recirculating flow in the IVC are observed superior to the bilateral renal vein inflows, and high flow velocities and elevated shear stresses are observed in the vicinity of renal inflow. Spherical thrombi induce stagnant and/or recirculating flow downstream of the thrombus. Placement of the TrapEase filter in the suprarenal vein position resulted in a large area of low shear stress/stagnant flow within the filter just downstream of thrombus trapped in the upstream trapping position. Filter position with respect to renal vein inflow influences the hemodynamics of filter trapping. Placement of the TrapEase filter in a suprarenal location may be thrombogenic with redundant areas of stagnant/recirculating flow and low shear stress along the caval wall due to the upstream trapping position and the naturally occurring region of stagnant flow from the renal veins. Infrarenal vein placement of IVC filters in a near juxtarenal position with the downstream cone near the renal vein inflow likely confers increased levels of mechanical lysis of trapped thrombi due to increased shear stress from renal vein inflow.
Date: July 13, 2009
Creator: Wang, S L & Singer, M A
Partner: UNT Libraries Government Documents Department

Development of an Automated Microfluidic System for DNA Collection, Amplification, and Detection of Pathogens

Description: This project was focused on developing and testing automated routines for a microfluidic Pathogen Detection System. The basic pathogen detection routine has three primary components; cell concentration, DNA amplification, and detection. In cell concentration, magnetic beads are held in a flow cell by an electromagnet. Sample liquid is passed through the flow cell and bacterial cells attach to the beads. These beads are then released into a small volume of fluid and delivered to the peltier device for cell lysis and DNA amplification. The cells are lysed during initial heating in the peltier device, and the released DNA is amplified using polymerase chain reaction (PCR) or strand displacement amplification (SDA). Once amplified, the DNA is then delivered to a laser induced fluorescence detection unit in which the sample is detected. These three components create a flexible platform that can be used for pathogen detection in liquid and sediment samples. Future developments of the system will include on-line DNA detection during DNA amplification and improved capture and release methods for the magnetic beads during cell concentration.
Date: December 1, 2002
Creator: Hagan, Bethany S. & Bruckner-Lea, Cynthia J.
Partner: UNT Libraries Government Documents Department

Mechanism of Excretion of a Bacterial Proteinase: Demonstration of Two Proteolytic Enzymes Produced by a Sarcina Strain (Coccus P)

Description: A Sarcina strain (Coccus P) produces two proteolytic enzymes. One is found only extracellularly, is far more prevalent, and is actively excreted during exponential growth. It is the enzyme responsible for the known strong proteolytic activity of the cultures of this strain. A second protease is, however, produced which remains associated with the intact cells but is released by the protoplasts. The two enzymes appear unrelated in their derivation. Calcium ions play an essential role in preventing autodigestion of the excreted enzyme. Bacterial proteins are found outside the cell boundary as a consequence either of passive processes such as leakage or lysis or of active excretion. Under conditions in which leakage and lysis do not occur, as during exponential growth, the cell boundary is a barrier causing a complete separation of the bulk of the intracellular proteins from the one or very few extracellular proteins, with no trace of either type being detectable on the wrong side of the boundary. Since in bacteria there is no evidence of protein being produced other than internally, the separation into intraand extracellular proteins should occur after peptide chain formation. The question arises as to whether the structure of the cell boundary or that of the excreted proteins themselves determines this separation. Coccus P, a Sarcina closely related to Micrococcus lysodeikticus (3), produces an extracellular proteinase during the exponential phase of growth so that the process appears to be active excretion. The organism grows exponentially in a defined synthetic medium (12) to relatively high cell density (10{sup 9} cells/ml); therefore the mechanism of excretion can be studied over an extended period of time without the difficulties of changing growth rates. Coagulation of reconstituted skim milk provides a simple and sensitive assay for enzyme activity (I 1). The extracellular proteinase has also been purified and ...
Date: June 29, 1970
Partner: UNT Libraries Government Documents Department

Rapid Automated Sample Preparation for Biological Assays

Description: Our technology utilizes acoustic, thermal, and electric fields to separate out contaminants such as debris or pollen from environmental samples, lyse open cells, and extract the DNA from the lysate. The objective of the project is to optimize the system described for a forensic sample, and demonstrate its performance for integration with downstream assay platforms (e.g. MIT-LL's ANDE). We intend to increase the quantity of DNA recovered from the sample beyond the current {approx}80% achieved using solid phase extraction methods. Task 1: Develop and test an acoustic filter for cell extraction. Task 2: Develop and test lysis chip. Task 3: Develop and test DNA extraction chip. All chips have been fabricated based on the designs laid out in last month's report.
Date: March 4, 2011
Creator: Shusteff, M
Partner: UNT Libraries Government Documents Department

Ultrasensitive detection of cell lysing in an microfabricated semiconductor laser cavity

Description: In this paper the authors report investigations of semiconductor laser microcavities for use in detecting changes of human blood cells during lysing. By studying the spectra before and during mixing of blood fluids with de-ionized water, they are able to quantify the cell shape and concentration of hemoglobin in real time during the dynamical process of lysing. The authors find that the spectra can detect subtle changes that are orders of magnitude smaller than can be observed by standard optical microscopy. Such sensitivity in observing cell structural changes has implications for measuring cell fragility, monitoring apoptotic events in real time, development of photosensitizers for photodynamic therapy, and in-vitro cell micromanipulation techniques.
Date: January 1, 1998
Creator: Gourley, P.L.; French, T.; McDonald, A.E.; Shields, E.A. & Gourley, M.F.
Partner: UNT Libraries Government Documents Department

Intelligent front-end sample preparation tool using acoustic streaming.

Description: We have successfully developed a nucleic acid extraction system based on a microacoustic lysis array coupled to an integrated nucleic acid extraction system all on a single cartridge. The microacoustic lysing array is based on 36{sup o} Y cut lithium niobate, which couples bulk acoustic waves (BAW) into the microchannels. The microchannels were fabricated using Mylar laminates and fused silica to form acoustic-fluidic interface cartridges. The transducer array consists of four active elements directed for cell lysis and one optional BAW element for mixing on the cartridge. The lysis system was modeled using one dimensional (1D) transmission line and two dimensional (2D) FEM models. For input powers required to lyse cells, the flow rate dictated the temperature change across the lysing region. From the computational models, a flow rate of 10 {micro}L/min produced a temperature rise of 23.2 C and only 6.7 C when flowing at 60 {micro}L/min. The measured temperature changes were 5 C less than the model. The computational models also permitted optimization of the acoustic coupling to the microchannel region and revealed the potential impact of thermal effects if not controlled. Using E. coli, we achieved a lysing efficacy of 49.9 {+-} 29.92 % based on a cell viability assay with a 757.2 % increase in ATP release within 20 seconds of acoustic exposure. A bench-top lysing system required 15-20 minutes operating up to 58 Watts to achieve the same level of cell lysis. We demonstrate that active mixing on the cartridge was critical to maximize binding and release of nucleic acid to the magnetic beads. Using a sol-gel silica bead matrix filled microchannel the extraction efficacy was 40%. The cartridge based magnetic bead system had an extraction efficiency of 19.2%. For an electric field based method that used Nafion films, a nucleic acid extraction efficiency of ...
Date: September 1, 2009
Creator: Cooley, Erika J.; McClain, Jaime L.; Murton, Jaclyn K.; Edwards, Thayne L.; Achyuthan, Komandoor E.; Branch, Darren W. et al.
Partner: UNT Libraries Government Documents Department

SPE water electrolysis technology development for large scale hydrogen production. Progress report No. 6, January 1, 1977--March 31, 1977

Description: The status of the following studies is reported: low cost current collector development, high temperature operation, catalytic electrode development, low cost polymer development, evaluation of the effect of hydrogen enrichment on older gas pipelines, cell and SPE optimization, cell assembly design, stack assembly design, manufacturing process development, and system analysis and definition.
Date: April 25, 1977
Partner: UNT Libraries Government Documents Department

Feasibility of electroplated gold for hybrid microcircuits. Final report

Description: Electroplated gold was investigated as a feasible alternative to vacuum evaporated gold for use as a conductive metallization layer on hybrid microcircuits (HMC) substrates. Conductor definition and resolution, RF electrical characteristics, via resistance, solder wettability, thermocompression bondability, and environmental stability of 6, 10 and 25 ..mu..m electroplated gold films were examined and compared to 6 ..mu..m evaporated gold films. No incompatibilities were found between electroplated gold and HMC requirements or fabrication processes.
Date: November 1, 1977
Creator: Blessner, P.L.
Partner: UNT Libraries Government Documents Department

Numerical studies of bubble dynamics in laser thrombolysis

Description: The applicability of modern numerical hydrodynamic methods for modeling the bubble dynamics occurring in Laser Thrombolysis is addressed. An idealized test problem is formulated and comparisons are made between numerical and analytical results. We find that approximately 23% of the available energy is radiated acoustically in one cycle with larger fractions likely to be radiated under more realistic conditions. We conclude that this approach shows promise in helping to optimize design parameters.
Date: March 1, 1996
Creator: Chapyak, E.J. & Godwin, R.P.
Partner: UNT Libraries Government Documents Department

Mechanical properties of electroplated nickel rings for bath aging study

Description: Hydraulic burst tests were performed on electroplated nickel rings as part of a bath aging study. Ring tensile properties were measured. An invalid failure mechanism was observed for rings having a significant gradient in wall thickness over the height. Finite element method (FEM) stress analysis models established the probable cause and helped set limits for future specimen dimension tolerances.
Date: November 1, 1979
Creator: Heffley, P.M.
Partner: UNT Libraries Government Documents Department

Studies on zinc nodules electrodeposited from acid electrolytes

Description: The development of morphology of electrodeposited zinc was investigated by studying the initial stages of deposition. Zinc was deposited galvanostatically from 1.0 M ZnCl/sub 2/ electrolyte (0.7 < pH < 4.6) on rotating disc electrodes at current densities from 5 to 130 ma/cm/sup 2/. Pine glassy carbon, Union Carbide pyrolytic graphite, Gould pyrolytic graphite, Exxon graphite loaded polymer, and platinum substrates were used. The number densities of nodules (diameter greater than 1 ..mu..m), typically encountered during incipient morphological development, were measured using scanning electron microscopy and image analysis. Nodule densities up to 7 x 10/sup 4/ nodules/mm/sup 2/ were measured.
Date: December 1, 1984
Creator: Anderson, R. & Tobias, C.W.
Partner: UNT Libraries Government Documents Department

Advanced alkaline water electrolysis. Task 2 summary report. Model for alkaline water electrolysis systems

Description: Task 2 involved the establishment of an engineering and economic model for the evaluation of various options in water electrolysis. The mode, verification of the specific coding and four case studies are described. The model was tested by evaluation of a nearly commercial technology, i.e., an 80-kW alkaline electrolyte system, operating at 60/sup 0/C, which delivers approximately 255 SLM, hydrogen for applications such as electrical generation cooling or semiconductor manufacturing. The calculated cost of hydrogen from this installed non-optimized case system with an initial cost to the customer of $87,000 was $6.99/Kg H/sub 2/ ($1.67/100 SCF) on a 20-yr levelized basis using 2.5 cents/kWh power costs. This compares favorably to a levelized average merchant hydrogen cost value of $9.11/Kg H/sub 2/ ($2.17/100 SCF) calculated using the same program.
Date: April 1, 1980
Creator: Yaffe, M.R. & Murray, J.N.
Partner: UNT Libraries Government Documents Department

The development of a micropatterned electrode for studies of zinc electrodeposition

Description: A micropatterned electrode was prepared for the study of electrocrystallization. Using microphotolithography, in conjunction with evaporation and pulse electrodeposition of thin films, a set of artificially roughened electrodes with hemispherical surface features five microns in diameter was developed. Voltammetric studies were conducted to determine the best electrode material. Gold, platinum, and various carbon surfaces were evaluated for zinc nucleation density and hydrogen overpotential. Surface homogeneity was examined by both light and scanning electron microscopy. Gold was determined to possess the best combination of material properties: chemical inertness, low melting point, and a high work function allowing underpotential deposition of zinc which reduces the rate of hydrogen evolution. Stripping coulometry was employed to determine zinc limiting currents, and evaluate effective diffusion coefficients in concentrated zinc chloride solutions. Although the method worked well for dilute zinc chloride and copper sulfate solutions, it failed at higher current densities; the emergence of surface roughness obscured actual limiting current plateaus.
Date: December 1, 1986
Creator: Sutija, D. P.; Muller, R. H. & Tobias, C. W.
Partner: UNT Libraries Government Documents Department

Microsystem strategies for sample preparation in biological detection.

Description: The objective of this LDRD was to develop microdevice strategies for dealing with samples to be examined in biological detection systems. This includes three sub-components: namely, microdevice fabrication, sample delivery to the microdevice, and sample processing within the microdevice. The first component of this work focused on utilizing Sandia's surface micromachining technology to fabricate small volume (nanoliter) fluidic systems for processing small quantities of biological samples. The next component was to develop interfaces for the surface-micromachined silicon devices. We partnered with Micronics, a commercial company, to produce fluidic manifolds for sample delivery to our silicon devices. Pressure testing was completed to examine the strength of the bond between the pressure-sensitive adhesive layer and the silicon chip. We are also pursuing several other methods, both in house and external, to develop polymer-based fluidic manifolds for packaging silicon-based microfluidic devices. The second component, sample processing, is divided into two sub-tasks: cell collection and cell lysis. Cell collection was achieved using dielectrophoresis, which employs AC fields to collect cells at energized microelectrodes, while rejecting non-cellular particles. Both live and dead Staph. aureus bacteria have been collected using RF frequency dielectrophoresis. Bacteria have been separated from polystyrene microspheres using frequency-shifting dielectrophoresis. Computational modeling was performed to optimize device separation performance, and to predict particle response to the dielectrophoretic traps. Cell lysis is continuing to be pursued using microactuators to mechanically disrupt cell membranes. Novel thermal actuators, which can generate larger forces than previously tested electrostatic actuators, have been incorporated with and tested with cell lysis devices. Significant cell membrane distortion has been observed, but more experiments need to be conducted to determine the effects of the observed distortion on membrane integrity and cell viability. Finally, we are using a commercial PCR DNA amplification system to determine the limits of detectable sample size, and to ...
Date: March 1, 2005
Creator: James, Conrad D.; Galambos, Paul C.; Bennett, Dawn Jonita (University of Maryland Baltimore County, Baltimore, MD); Manginell, Monica; Okandan, Murat; Acrivos, Andreas (The City College of New York, NY) et al.
Partner: UNT Libraries Government Documents Department

Magnetophoretic bead trapping in a high-flowrate biological detection system.

Description: This report contains the summary of the 'Magnetophoretic Bead Trapping in a High-Flowrate Biological Detection System' LDRD project 74795. The objective of this project is to develop a novel biodetection system for high-throughput sample analysis. The chief application of this system is in detection of very low concentrations of target molecules from a complex liquid solution containing many different constituents--some of which may interfere with identification of the target molecule. The system is also designed to handle air sampling by using an aerosol system (for instance a WESP - Wet Electro-Static Precipitator, or an impact spray system) to get air sample constituents into the liquid volume. The system described herein automatically takes the raw liquid sample, whether air converted or initially liquid matrix, and mixes in magnetic detector beads that capture the targets of interest and then performs the sample cleanup function, allowing increased sensitivity and eliminating most false positives and false negatives at a downstream detector. The surfaces of the beads can be functionalized in a variety of ways in order to maximize the number of targets to be captured and concentrated. Bacteria and viruses are captured using antibodies to surface proteins on bacterial cell walls or viral particle coats. In combination with a cell lysis or PCR (Polymerase Chain Reaction), the beads can be used as a DNA or RNA probe to capture nucleic acid patterns of interest. The sample cleanup capability of this system would allow different raw biological samples, such as blood or saliva to be analyzed for the presence of different infectious agents (e.g. smallpox or SARS). For future studies, we envision functionalizing bead surfaces to bind to chemical weapons agents, radio-isotopes, and explosives. The two main objectives of this project were to explore methods for enhancing the mixing of the capture microspheres in the ...
Date: March 1, 2005
Creator: Galambos, Paul C.; Hopkins, Matthew Morgan; Rahimian, Kamayar; Martin, James Ellis; Anderson, G. Ronald; Clem, Paul Gilbert et al.
Partner: UNT Libraries Government Documents Department

Survey of organic electrolytic processes. Final report

Description: The basic objectives of this study were to review the literature to determine the commercial status of electroorganic processes and to estimate whether there would be significant possible energy savings by introduction of electroorganic processes to replace conventional chemical processes for production of certain large-tonnage organic chemicals. A list was compiled of the 220 organic chemicals that were produced at greater than 10,000 tons per year in 1975 in the United States. Search of the Swann and of the Fichter Bibliographies of electroorganic literature yielded references on 95 of these compounds. By application of selection rules to obtain promising candidates, nine chemicals with diverse electrochemical processes were chosen for detailed process energy calculations. Parallel calculations were made for presently-used commercial chemical routes to these products. Two of the nine electrochemical processes, adiponitrile and methyl ethyl ketone, had energy savings in comparison to the corresponding chemical processes. Other more-energy-efficient electrochemical processes are likely among the above 95, although they remain to be identified.
Date: November 1, 1979
Partner: UNT Libraries Government Documents Department

SPE water electrolysis technology development for large scale hydrogen production. Progress report No. 4, June 15, 1976--September 30, 1976

Description: Porous carbon fiber paper was selected as the cathode membrane and electrode assembly support based on over 1200 hr operational evaluation. Three potential anode supports are under test. All three appear technically satisfactory after 500 to 1200 hr operational evaluation on each. Optimization of molds and molding techniques for a foil backed ribbed carbon collector of bipolar design, including ribbed flow fields, manifolds, ports and sealing surfaces, is in process. Over 2800 hr demonstrated at 300/sup 0/F on platinum screened cell. Over 2200 hr demonstrated at 300/sup 0/F on cell with carbon cloth cathode current collector. Forty-eight hours screening tests of 56 different anode catalysts have been completed. A 500-hr life test program of 12 anode catalyst types which showed promise on the screening tests has been started. Attempts to stabilize RuO/sub x/ for use as an anode catalyst are being pursued. Low loaded cathodes on graphite substrates show performance to within 25 MV of baseline. Optimization of substrate thickness and fabrication procedures is continuing. Twenty-five low loaded anodes catalyst/substrate combinations have all shown poor performance stability with time. Continued development of the grafted TFS membrane has shown greatly improved physical characteristics and encouraging performance for samples in the 25 to 45 percent graft level range. In the cell and SPE optimization work, initial testing of cells with tandem (anion/cation monobed followed by cation only) deionizers show improved voltage invariance. Evaluation of a hydraulically loaded cell test fixture which eliminates gaskets and gives uniform cell compression was completed. Hydraulic fixtures are being factored into the low cost current collector and high temperature operation tasks.
Date: October 7, 1976
Partner: UNT Libraries Government Documents Department

Fabrication of ion source components by electroforming

Description: Several components of the Oak Ridge National Laboratory (ORNL)/Magnetic Fusion Test Facility (MFTF-B) ion source have been fabricated utilizing an electroforming process. A procedure has been developed for enclosing coolant passages in copper components by electrodepositing a thick (greater than or equal to 0.75-mm) layer of copper (electroforming) over the top of grooves machined into the copper component base. Details of the procedure to fabricate acceleration grids and other ion source components are presented.
Date: January 1, 1983
Creator: Schechter, D.E. & Sluss, F.
Partner: UNT Libraries Government Documents Department

Hydrogen gas from cured RTV silicones

Description: Eight different RTV silicones were sealed in containers, and after preselected times the amount of hydrogen in the containers was determined. The silicone samples were conditioned at 80/sup 0/C in a 100% RH air atmosphere and at 23/sup 0/C in a dry air atmosphere. The amount of gas from duplicate samples varied considerably. The cause of these variations was investigated, and it was determined that humidity in a helium atmosphere produced the maximum hydrogen, and the amount of hydrogen is less if oxygen is present in the atmosphere. 10 figures, 3 tables.
Date: October 1, 1977
Creator: Myers, L.C.
Partner: UNT Libraries Government Documents Department

''Aged'' (dense) circulating red cells contain normal concentrations of ATP

Description: A newly-developed technique for determination of the ATP content of individual red cells to the densest, and hence presumably the oldest, cells from normal human blood was applied. It was found that these cells contain normal concentrations of ATP, although the net content of ATP is decreased. The essence of the technique is suspension of red cells in autologous plasma containing luciferin and luciferase, lysis of the cells with a pulse from a laser, and counting of the photoemissions resulting from reaction of the released ATP with the luciferase. These data appear to disprove the otherwise plausible hypothesis of Lichtman that red cells decline exponentially in ATP content as they age, by one of the suggested tests of this hypothesis. The data suggest an alternative hypothesis: red cells maintain an approximately constant concentration of ATP as they age, and red cell destruction is caused by factors other than cellular ATP.
Date: January 1, 1978
Creator: Kirkpatrick, F.H.; Muhs, A.G.; Kostuk, R.K. & Gabel, C.W.
Partner: UNT Libraries Government Documents Department

Energy savings by means of fuel cell electrodes in electro-chemical industries. Progress report, August 1, 1979-October 31, 1979

Description: Initial efforts in studies of the effects of fuel cell electrodes on energy savings in electrochemical processes have been directed toward assembling test hardware and evaluation of a new zinc plant feed. A complete chemical analysis of the feed is reported. Utilizing the 2'' x 2'' (active electrode area) hardware and techniques developed under Contract No. ET-78-C-02-4881, 6 h zinc electrowinning tests demonstrated a current efficiency of greater than 90% with an energy consumption of 0.54 to 0.55 kWh/lb of zinc. For these tests, 0.1 g/l gelatin was employed as an electrolyte additive and the resultant zinc plates were bright, smooth and compact.
Date: December 12, 1979
Creator: Allen, R.J.; Juda, W. & Lindstrom, R.W.
Partner: UNT Libraries Government Documents Department