Search Results

Advanced search parameters have been applied.
open access

Hybrid collimation for industrial gamma-ray imaging.

Description: Portable photon imaging devices with a broad energy range of sensitivity, adequate angular resolution and high efficiency are useful in applications such as environmental remediation and industrial surveys. The vast majority of past systems built for these applications have relied on mechanical collimation although a few have used electronic collimation. To our knowledge, no devices have been built that exploit the benefits of both mechanical and electronic collimation in the same system. The c… more
Date: June 22, 1999
Creator: He, Z.; Knoll, G. F.; Smith, L. E. & Wehe, D. K.
Partner: UNT Libraries Government Documents Department
open access

The Effect of Compton Scattering on the Double to Single Ionization Ratio in Helium

Description: The ratio of double to single ionization in Helium produced by photon impact has been measured for photon energies from 2.1 to 5.5 keV. The measurements suggest that a significant contribution to the single ionization cross section is caused by Compton scattering for energies greater than {approximately} 3.8 keV. After accounting for the ionizing Compton scattering the measured ratio is not inconsistent with recent calculations of the asymptotic limit of the ionization ratio caused by photoabso… more
Date: October 1993
Creator: Bartlett, R. J.; Sagurton, M.; Samson, J. A. R. & He, Z. X.
Partner: UNT Libraries Government Documents Department
open access

Advanced devices and systems for radiation measurements

Description: The authors` most recent work continues their long-standing efforts to develop semiconductor detectors based on the collection of only a single type of charge carrier. Their best results are an extension of the principle of coplanar electrodes first described by Paul Luke of Lawrence Berkeley Laboratory 18 months ago. This technique, described in past progress reports, has the effect of deriving an output signal from detectors that depends only on the motion of carriers close to one surface. Si… more
Date: June 1, 1996
Creator: Knoll, G. F.; Wehe, D. K.; He, Z.; Barrett, C. & Miyamoto, J.
Partner: UNT Libraries Government Documents Department
open access

Olefin Recovery from Chemical Industry Waste Streams

Description: The objective of this project was to develop a membrane process to separate olefins from paraffins in waste gas streams as an alternative to flaring or distillation. Flaring these streams wastes their chemical feedstock value; distillation is energy and capital cost intensive, particularly for small waste streams.
Date: November 21, 2003
Creator: Costa, A.R. Da; Daniels, R.; Jariwala, A.; He, Z.; Morisato, A.; Pinnau, I. et al.
Partner: UNT Libraries Government Documents Department
open access

The use of microarrays in microbial ecology

Description: Microarrays have proven to be a useful and high-throughput method to provide targeted DNA sequence information for up to many thousands of specific genetic regions in a single test. A microarray consists of multiple DNA oligonucleotide probes that, under high stringency conditions, hybridize only to specific complementary nucleic acid sequences (targets). A fluorescent signal indicates the presence and, in many cases, the abundance of genetic regions of interest. In this chapter we will look at… more
Date: September 15, 2009
Creator: Andersen, G. L.; He, Z.; DeSantis, T. Z.; Brodie, E. L. & Zhou, J.
Partner: UNT Libraries Government Documents Department
open access

READOUT ASIC FOR 3D POSITION-SENSITIVE DETECTORS.

Description: We describe an application specific integrated circuit (ASIC) for 3D position-sensitive detectors. It was optimized for pixelated CZT sensors, and it measures, corresponding to an ionizing event, the energy and timing of signals from 121 anodes and one cathode. Each channel provides low-noise charge amplification, high-order shaping, along with peak- and timing-detection. The cathode's timing can be measured in three different ways: the first is based on multiple thresholds on the charge amplif… more
Date: October 27, 2007
Creator: DE GERONIMO,G.; VERNON, E.; ACKLEY, K.; DRAGONE, A.; FRIED, J.; OCONNOR, P. et al.
Partner: UNT Libraries Government Documents Department
open access

Response of Desulfovibrio vulgaris to Alkaline Stress

Description: The response of exponentially growing Desulfovibrio vulgarisHildenborough to pH 10 stress was studied using oligonucleotidemicroarrays and a study set of mutants with genes suggested by microarraydata to be involved in the alkaline stress response deleted. The datashowed that the response of D. vulgaris to increased pH is generallysimilar to that of Escherichia coli but is apparently controlled byunique regulatory circuits since the alternative sigma factors (sigma Sand sigma E) contributing to… more
Date: November 30, 2007
Creator: Stolyar, S.; He, Q.; He, Z.; Yang, Z.; Borglin, S. E.; Joyner, D. et al.
Partner: UNT Libraries Government Documents Department
open access

Temporal transcriptomic analysis of Desulfovibrio vulgaris Hildenborough transition into stationary phase growth during electrondonor depletion

Description: Desulfovibrio vulgaris was cultivated in a defined medium, and biomass was sampled for approximately 70 h to characterize the shifts in gene expression as cells transitioned from the exponential to the stationary phase during electron donor depletion. In addition to temporal transcriptomics, total protein, carbohydrate, lactate, acetate, and sulfate levels were measured. The microarray data were examined for statistically significant expression changes, hierarchical cluster analysis, and promot… more
Date: August 1, 2006
Creator: Clark, M. E.; He, Q.; He, Z.; Huang, K. H.; Alm, E. J.; Wan, X. -F. et al.
Partner: UNT Libraries Government Documents Department
open access

NITROGEN REMOVAL FROM NATURAL GAS

Description: The objective of this project was to develop a membrane process for the denitrogenation of natural gas. Large proven reserves in the Lower-48 states cannot be produced because of the presence of nitrogen. To exploit these reserves, cost-effective, simple technology able to reduce the nitrogen content of the gas to 4-5% is required. Technology applicable to treatment of small gas streams (below 10 MMscfd) is particularly needed. In this project membranes that selectively permeate methane and rej… more
Date: December 31, 1999
Creator: Lokhandwala, K. A.; Ringer, M. B.; Su, T. T.; He, Z.; Pinnau, I.; Wijmans, J. G. et al.
Partner: UNT Libraries Government Documents Department
open access

Global Analysis of Heat Shock Response in Desulfovibrio vulgaris Hildenborough.

Description: Desulfovibrio vulgaris Hildenborough belongs to a class ofsulfate-reducing bacteria (SRB) and is found ubiquitously in nature.Given the importance of SRB-mediated reduction for bioremediation ofmetal ion contaminants, ongoing research on D. vulgaris has been in thedirection of elucidating regulatory mechanisms for this organism under avariety of stress conditions. This work presents a global view of thisorganism's response to elevated growth temperature using whole-celltranscriptomics and prote… more
Date: September 16, 2005
Creator: Chhabra, S. R.; He, Q.; Huang, K. H.; Gaucher, S. P.; Alm, E. J.; He, Z. et al.
Partner: UNT Libraries Government Documents Department
open access

GeoChip 3.0 as a high-thoughput tool for analyzing microbial community composition, structure, and functional activity

Description: A new generation of functional gene arrays (FGAs; GeoChip 3.0) has been developed, with {approx}28,000 probes covering approximately 57,000 gene variants from 292 functional gene families involved in carbon, nitrogen, phosphorus and sulfur cycles, energy metabolism, antibiotic resistance, metal resistance and organic contaminant degradation. GeoChip 3.0 also has several other distinct features, such as a common oligo reference standard (CORS) for data normalization and comparison, a software pa… more
Date: April 1, 2010
Creator: He, Z.; Deng, Y.; Van Nostrand, J.D.; Tu, Q.; Xu, M.; Hemme, C.L. et al.
Partner: UNT Libraries Government Documents Department
open access

How sulphate-reducing microorganisms cope with stress: Lessons from systems biology

Description: Sulphate-reducing microorganisms (SRMs) are a phylogenetically diverse group of anaerobes encompassing distinct physiologies with a broad ecological distribution. As SRMs have important roles in the biogeochemical cycling of carbon, nitrogen, sulphur and various metals, an understanding of how these organisms respond to environmental stresses is of fundamental and practical importance. In this Review, we highlight recent applications of systems biology tools in studying the stress responses of … more
Date: April 1, 2011
Creator: Zhou, J.; He, Q.; Hemme, C. L.; Mukhopadhyay, A.; Hillesland, K.; Zhou, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Metagenomic insights into evolution of heavy metal-contaminated groundwater microbial community

Description: Understanding adaptation of biological communities to environmental change is a central issue in ecology and evolution. Metagenomic analysis of a stressed groundwater microbial community reveals that prolonged exposure to high concentrations of heavy metals, nitric acid and organic solvents ({approx}50 years) has resulted in a massive decrease in species and allelic diversity as well as a significant loss of metabolic diversity. Although the surviving microbial community possesses all metabolic… more
Date: July 1, 2010
Creator: Hemme, C. L.; Deng, Y.; Gentry, T. J.; Fields, M. W.; Wu, L.; Barua, S. et al.
Partner: UNT Libraries Government Documents Department
open access

CFD ANALYSES ON THE COOLING FOR SCQ MAGNETS IN BEPC II UPGRADE.

Description: A pair of superconducting interaction region quadrupole magnets in Beijing Electron-Positron Collider Upgrade (BEPCII) are to be cooled by supercritical helium in order to eliminate the flow instabilities in the constrained cooling channels. The fluid flow is simulated by the commercial computational dynamics fluid software. The heat loads to the superconducting quadrupole (SCQ) magnets from the radiation shields at 80 K and from the thermal conduction of mechanical supports are considered. The… more
Date: September 22, 2003
Creator: HE,Z. H. WANG,L. TANK,H. M. ZHANG,X. B. JIA,L. X.
Partner: UNT Libraries Government Documents Department
open access

Microbial gene functions enriched in the Deepwater Horizon deep-sea oil plume

Description: The Deepwater Horizon oil spill in the Gulf of Mexico is the deepest and largest offshore spill in U.S. history and its impacts on marine ecosystems are largely unknown. Here, we showed that the microbial community functional composition and structure were dramatically altered in a deep-sea oil plume resulting from the spill. A variety of metabolic genes involved in both aerobic and anaerobic hydrocarbon degradation were highly enriched in the plume compared to outside the plume, indicating a g… more
Date: June 15, 2011
Creator: Lu, Z.; Deng, Y.; Nostrand, J. D. Van; He, Z.; Voordeckers, J.; Zhou, A. et al.
Partner: UNT Libraries Government Documents Department
open access

Dynamics of microbial community composition and function during in-situ bioremediation of a uranium-contaminated aquifer

Description: A pilot-scale system was established to examine the feasibility of in situ U(VI) immobilization at a highly contaminated aquifer (U.S. DOE Integrated Field Research Challenge site, Oak Ridge, TN). Ethanol was injected intermittently as an electron donor to stimulate microbial U(VI) reduction, and U(VI) concentrations fell to below the Environmental Protection Agency drinking water standard (0.03 mg liter{sup -1}). Microbial communities from three monitoring wells were examined during active U(V… more
Date: August 15, 2010
Creator: Van Nostrand, J. D.; Wu, L.; Wu, W. M.; Huang, A.; Gentry, T. J.; Deng, Y. et al.
Partner: UNT Libraries Government Documents Department
open access

Responses of microbial community functional structures to pilot-scale uranium in situ bioremediation

Description: A pilot-scale field test system with an inner loop nested within an outer loop was constructed for in situ U(VI) bioremediation at a US Department of Energy site, Oak Ridge, TN. The outer loop was used for hydrological protection of the inner loop where ethanol was injected for biostimulation of microorganisms for U(VI) reduction/immobilization. After 2 years of biostimulation with ethanol, U(VI) levels were reduced to below drinking water standard (<30 {micro}gl{sup -1}) in the inner loop m… more
Date: February 15, 2010
Creator: Xu, M.; Wu, W.-M.; Wu, L.; He, Z.; Van Nostrand, J.D.; Deng, Y. et al.
Partner: UNT Libraries Government Documents Department
open access

Impact of elevated nitrate on sulfate-reducing bacteria: A comparative study of Desulfovibrio vulgaris

Description: Sulfate-reducing bacteria have been extensively studied for their potential in heavy-metal bioremediation. However, the occurrence of elevated nitrate in contaminated environments has been shown to inhibit sulfate reduction activity. Although the inhibition has been suggested to result from the competition with nitrate-reducing bacteria, the possibility of direct inhibition of sulfate reducers by elevated nitrate needs to be explored. Using Desulfovibrio vulgaris as a model sulfate-reducing bac… more
Date: July 15, 2010
Creator: He, Q.; He, Z.; Joyner, D. C.; Joachimiak, M.; Price, M. N.; Yang, Z. K. et al.
Partner: UNT Libraries Government Documents Department
Back to Top of Screen