12 Matching Results

Search Results

Advanced search parameters have been applied.

Morphology of Azotobacter vinelandii grown on nutrient agar

Description: This research deals with the changes in cellular morphology of Azotobacter vinelandii cultured on nutrient agar. In particular, this study is concerned with the formation of intracellular particles and a description of their size and sequence of appearance. Changes in morphology of Azotobacter vinelandii grown on nutrient agar are contrasted photographically with morphology of Azotobacter vinelandii grown on Burk's nitrogen free medium.
Date: May 1984
Creator: Hartnett, Glenna Hollar
Partner: UNT Libraries

Purification and characterization of a differentiation factor from rat lung conditioned medium

Description: A Differentiation Factor (DF) was purified from rat lung conditioned medium by a four-steps procedure. The DF has a molecular weight of 27000, and an isoelectric point of 4.70. Although DF is stable up to 60°C, it is sensitive to digestion by trypsin, chymotrypsin and subtilisin. DF forms granulocyte colonies in soft agar. Studies using anti-NRK CSF antibody demonstrated that DF is distinct from GM-CSF.
Date: May 1988
Creator: Ansari, Naser A. (Naser Awni)
Partner: UNT Libraries

Resistance and morphology of Azotobacter vinelandii grown on dialyzed soil agar

Description: The objectives of this research were to identify the form of Azotobacter as it exists in situ in the soil; to compare its resistance to that of laboratory grown cysts typical of those described in the literature; and to compare its resistance to that of cells grown on dialyzed soil agar.
Date: May 1987
Creator: Gogu, Sudhir Reddy
Partner: UNT Libraries

Low density, microcellular, dopable, agar/gelatin foams for pulsed power experiments

Description: Low-density, microcellular foams prepared from the natural polymers agar and gelatin have been developed for pulsed-power physics experiments. Numerous experiments were supported with foams having densities at or below 10 mg/cm{sup 3}. For some of the experiments, the agar/gelatin foam was uniformly doped with metallic elements using soluble salts. Depending on the method of preparation, cell sizes were typically below 10 microns and for one process were below 1.0 micron.
Date: April 1997
Creator: McNamara, W. F. & Aubert, J. H.
Partner: UNT Libraries Government Documents Department

Time-resolved x-ray imaging of high-power laser-irradiated under-dense silica aerogels and agar foams

Description: This paper presents the results of experiments in which a high-power laser was used to irradiate low density (4 - 9 mg/cm{sup 3}) silica aerogel and agar foam targets. The laser-solid interaction and energy transport through the material were monitored with time-resolved imaging diagnostics, and the data show the production and propagation of an x-ray emission front in the plasma. The emission-front trajectory data are found to be in significant disagreement with detailed simulations, which predict a much more rapid heating of the cold material, and the data suggest that this discrepancy is not explainable by target inhomogeneities. Evidence suggests that energy transport into the cold material may be dominated by thermal conduction; however, no completely satisfactory explanation for the discrepancies is identified, and further experimental and theoretical research is necessary in order to resolve this important problem in laser-plasma interaction physics.
Date: August 1, 1995
Creator: Koch, J.A.; Estabrook, K.G. & Bauer, J.D.
Partner: UNT Libraries Government Documents Department

Differential sensitivity of aerobic gram-positive and gram-negative microorganisms to 2,4,6-trinitrotoluene (TNT) leads to dissimilar growth and TNT transformation: Results of soil and pure culture studies

Description: The effects of 2,4,6-trinitrotoluene (TNT) on indigenous soil populations and pure bacterial cultures were examined. The number of colony-forming units (CFU) appearing when TNT-contaminated soil was spread on 0.3% molasses plates decreased by 50% when the agar was amended with 67 {mu}g TNT mL{sup -1}, whereas a 99% reduction was observed when uncontaminated soil was plated. Furthermore, TNT-contaminated soil harbored a greater number of organisms able to grow on plates amended with greater than 10 {mu}g TNT mL{sup -1}. The percentage of gram-positive isolates was markedly less in TNT-contaminated soil (7%; 2 of 30) than in uncontaminated soil (61%; 20 of 33). Pseudomonas aeruginosa, Pseudomonas corrugate, Pseudomonasfluorescens and Alcaligenes xylosoxidans made up the majority of the gram-negative isolates from TNT-contaminated soil. Gram-positive isolates from both soils demonstrated marked growth inhibition when greater than 8-16 {mu}g TNT mL{sup -1} was present in the culture media. Most pure cultures of known aerobic gram-negative organisms readily degraded TNT and evidenced net consumption of reduced metabolites. However, pure cultures of aerobic gram-positive bacteria were sensitive to relatively low concentrations of TNT as indicated by the 50% reduction in growth and TNT transformation which was observed at approximately 10 {mu}g TNT mL{sup -1}. Most non-sporeforming gram-positive organisms incubated in molasses media amended with 80 {mu}g TNT mL{sup -1} or greater became unculturable, whereas all strains tested remained culturable when incubated in mineral media amended with 98 {mu}g TNT mL{sup -1}, indicating that TNT sensitivity is likely linked to cell growth. These results indicate that gram-negative organisms are most likely responsible for any TNT transformation in contaminated soil, due to their relative insensitivity to high TNT concentrations and their ability to transform TNT.
Date: July 30, 1996
Creator: Fuller, M.E. & Manning, J.F. Jr.
Partner: UNT Libraries Government Documents Department

Development of an integrated, in-situ remediation technology: Task 2--4, electrokinetic modeling. Topical report, September 26--May 25, 1996

Description: This report summarizes the work conducted in Tasks 2-4, which together make up the Electrokinetic Modeling carried out in this project. The modeling was divided into three main sections: thermal analysis, chemical species transport, and electrode geometry and soil heterogeneity issues. The thermal modeling consisted of development of the governing equations to incorporate Joule heating associated with electro-osmosis, heat conduction and convection, and temperature dependencies of electrical conductivity and electro-osmotic permeability. To model the transport of chemical species in the Lasagna{sup TM} process, a one-dimensional model was developed. This model is based on previous models, but includes additional mechanism to account for charge transfer in the double layer, pH buffering of the soil, and zeta potential dependency on pH and ionic strength. The results of this model and the corroboration by experimental measurement support some key assumptions made in the thermal model. An analysis was also conducted to compare the use of cylindrical electrodes to the plate geometry used in Phase I. In summary, cylindrical electrodes may be appropriate for anodes, because the do not intercept the flow. If used as cathodes, a planar treatment zone in their vicinity would probably be required. The cylindrical electrodes can operate at reasonable current densities without boiling water. Because the hottest region is at the electrode, cooling schemes could be used to operate at higher current densities. If iron anodes are used, they will have to be quite massive, and may not be economical compared to planar models. An example of soil heterogeneity was investigated when it was discovered that a steel pt was buried in the vicinity of the pilot test. There is some distortion of the field near the pit, but its effects on the test zone between the electrodes are minimal.
Date: May 1, 1997
Partner: UNT Libraries Government Documents Department

Spectroscopic diagnosis of foam z-pinch plasmas on SATURN

Description: Solid and annular silicon aerogel and agar foams were shot on the accelerator SATURN to study plasma initiation, acceleration, and stagnation. SATURN delivers 7 MA with a 50 nsec rise time to these foam loads. We fielded several spectroscopic diagnostics to measure plasma parameters throughout the z-pinch discharge. A spatially resolved single frame time-gated EUV spectrometer measured the extent of plasma ablation off the surface foam. A time integrated crystal spectrometer showed that characteristic K shell radiation of silicon in the aerogel and of S and Na impurities in the agar were all attenuated when the foam loads were coated with a conductive layer of gold. The time resolved pinhole camera showed that in general the quality of the pinch implosions was poor but improved with increasing efforts to improve current continuity such as prepulse and conductive coatings.
Date: June 1996
Creator: Nash, T. J.; Derzon, M. S.; Allshouse, G.; Deeney, C.; Jobe, D.; McGurn, J. et al.
Partner: UNT Libraries Government Documents Department

Current initiation in low-density foam z-pinch plasmas

Description: Low density agar and aerogel foams were tested as z-pinch loads on the SATURN accelerator. In these first experiments, we studied the initial plasma conditions by measuring the visible emission at early times with a framing camera and 1-D imaging. At later time, near the stagnation when the plasma is hotter, x-ray imaging and spectral diagnostics were used to characterize the plasma. Filamentation and arcing at the current contacts was observed. None of the implosions were uniform along the z-axis. The prime causes of these problems are believed to be the electrode contacts and the current return configuration and these are solvable. Periodic phenomena consistent with the formation of instabilities were observed on one shot, not on others, implying that there may be a way of controlling instabilities in the pinch. Many of the issues involving current initiation may be solvable. Solutions are discussed.
Date: July 1, 1996
Creator: Derzon, M.; Nash, T. & Allshouse, G.
Partner: UNT Libraries Government Documents Department

QNS measurements on water in biological and model systems

Description: Results are presented on the quasi-elastic spectra of 0.95 THz neutrons scattered from pure water, a 20% agarose gel and cysts of the brine shrimp (Artemia) of hydration 1.2 gms H/sub 2/O per gm of dry solids. The lines are interpreted with a two-component model in which the hydration water scatters elastically and the free water is described by a jump-diffusion correlation function. The results for the line widths GAMMA(Q/sup 2/) are in good agreement with previous measurements for the water sample but show deviations from pure water at large Q for agarose and the Artemia cysts that suggest an increased value of the residence time in the jump-diffusion model.
Date: January 1, 1981
Creator: Trantham, E.C.; Rorschach, H.E.; Clegg, J.C.; Hazlewood, C.F. & Nicklow, R.M.
Partner: UNT Libraries Government Documents Department

Biotechnology and genetic optimization of fast-growing hardwoods

Description: A biotechnology research program was initiated to develop new clones of fast-growing Populus clones resistant to the herbicide glyphosate and resistant to the leaf-spot and canker disease caused by the fungus Septoria musiva. Glyphosate-resistant callus was selected from stem segments cultured in vitro on media supplemented with the herbicide. Plants were regenerated from the glyphosate-resistant callus tissue. A portion of plants reverted to a glyphosate susceptible phenotype during organogenesis. A biologically active filtrate was prepared from S. musiva and influenced fresh weight of Populus callus tissue. Disease-resistant plants were produced through somaclonal variation when shoots developed on stem internodes cultured in vitro. Plantlets were screened for disease symptoms after spraying with a suspension of fungal spores. A frequency of 0.83 percent variant production was observed. Genetically engineered plants were produced after treatment of plant tissue with Agrobacterium tumefasciens strains carrying plasmid genes for antibiotic resistance. Transformers were selected on media enriched with the antibiotic, kanamycin. Presence of foreign DNA was confirmed by Southern blot analysis. Protoplasts of popular were produced but did not regenerate into plant organs. 145 refs., 12 figs., 36 tabs.
Date: February 1, 1991
Creator: Garton, S.; Syrkin-Wurtele, E.; Griffiths, H.; Schell, J.; Van Camp, L. & Bulka, K. (NPI, Salt Lake City, UT (United States))
Partner: UNT Libraries Government Documents Department