Chemistry of the Colloidal Group II-VI Nanocrystal Synthesis (open access)

Chemistry of the Colloidal Group II-VI Nanocrystal Synthesis

In the last two decades, the field of nanoscience andnanotechnology has witnessed tremendous advancement in the synthesis andapplication of group II-VI colloidal nanocrystals. The synthesis based onhigh temperature decomposition of organometallic precursors has becomeone of the most successful methods of making group II-VI colloidalnanocrystals. This method is first demonstrated by Bawendi and coworkersin 1993 to prepare cadmium chalcogenide colloidal quantum dots and laterextended by others to prepare other group II-VI quantum dots as well asanisotropic shaped colloidal nanocrystals, such as nanorod and tetrapod.This dissertation focuses on the chemistry of this type of nanocrystalsynthesis. The synthesis of group II-VI nanocrystals was studied bycharacterizing the molecular structures of the precursors and productsand following their time evolution in the synthesis. Based on theseresults, a mechanism was proposed to account for the 2 reaction betweenthe precursors that presumably produces monomer for the growth ofnanocrystals. Theoretical study based on density functional theorycalculations revealed the detailed free energy landscape of the precursordecomposition and monomerformation pathway. Based on the proposedreaction mechanism, a new synthetic method was designed that uses wateras a novel reagent to control the diameter and the aspect ratio of CdSeand CdS nanorods.
Date: May 17, 2007
Creator: Liu, Haitao
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Chemistry of the Colloidal Group II-VI Nanocrystal Synthesis (open access)

Chemistry of the Colloidal Group II-VI Nanocrystal Synthesis

In the last two decades, the field of nanoscience andnanotechnology has witnessed tremendous advancement in the synthesis andapplication of group II-VI colloidal nanocrystals. The synthesis based onhigh temperature decomposition of organometallic precursors has becomeone of the most successful methods of making group II-VI colloidalnanocrystals. This methodis first demonstrated by Bawendi and coworkersin 1993 to prepare cadmium chalcogenide colloidal quantum dots and laterextended by others to prepare other group II-VI quantum dots as well asanisotropic shaped colloidal nanocrystals, such as nanorod and tetrapod.This dissertation focuses on the chemistry of this type of nanocrystalsynthesis. The synthesis of group II-VI nanocrystals was studied bycharacterizing the molecular structures of the precursors and productsand following their time evolution in the synthesis. Based on theseresults, a mechanism was proposed to account for the 2 reaction betweenthe precursors that presumably produces monomer for the growth ofnanocrystals. Theoretical study based on density functional theorycalculations revealed the detailed free energy landscape of the precursordecomposition and monomerformation pathway. Based on the proposedreaction mechanism, a new synthetic method was designed that uses wateras a novel reagent to control the diameter and the aspect ratio of CdSeand CdS nanorods.
Date: May 17, 2007
Creator: Liu, Haitao
Object Type: Thesis or Dissertation
System: The UNT Digital Library

Controlled Hydrogen Fleet and Infrastructure Analysis

This presentation by Keith Wipke at the 2007 DOE Hydrogen Program Annual Merit Review Meeting provides information about NREL's Controlled Hydrogen Fleet and Infrastructure Analysis Project.
Date: May 17, 2007
Creator: Wipke, K.
Object Type: Presentation
System: The UNT Digital Library
Final Report and Strategic Plan on the Feasibility Study to Assess Geothermal Potential on Warm Springs Reservation Lands. (open access)

Final Report and Strategic Plan on the Feasibility Study to Assess Geothermal Potential on Warm Springs Reservation Lands.

In 2005 the Confederated Tribes of Warm Springs Tribal Council authorized an evaluation of the geothermal development potential on the Confederated Tribes of Warm Springs Reservation of Oregon. Warm Springs Power & Water Enterprises obtained a grant from the U.S. Department of Energy to conduct a geological assessment and development estimate. Warm Springs Power & Water Enterprises utilized a team of expert consultants to conduct the study and develop a strategic plan. The resource assessment work was completed in 2006 by GeothermEx Inc., a consulting company specializing in geothermal resource assessments worldwide. The GeothermEx report indicates there is a 90% probability that a commercial geothermal resource exists on tribal lands in the Mt. Jefferson area. The geothermal resource assessment and other cost, risk and constraints information has been incorporated into the strategic plan.
Date: May 17, 2007
Creator: Manion, James & McClain, David
Object Type: Report
System: The UNT Digital Library

Geographically-Based Hydrogen Demand & Infrastructure Rollout Scenario Analysis

This presentation by Margo Melendez at the 2007 DOE Hydrogen Program Annual Merit Review Meeting provides information about NREL's Hydrogen Demand & Infrastructure Rollout Scenario Analysis.
Date: May 17, 2007
Creator: Melendez, M.
Object Type: Presentation
System: The UNT Digital Library

HyDRA: Hydrogen Demand and Resource Analysis Tool

None
Date: May 17, 2007
Creator: Levene, J.
Object Type: Presentation
System: The UNT Digital Library

Hydrogen Codes and Standards

Presentation on Hydrogen Codes and Standards.
Date: May 17, 2007
Creator: Ohi, J.; Hewett, R.; Burgess, R.; Barley, D.; Gawlik, K.; Thomas, J. et al.
Object Type: Presentation
System: The UNT Digital Library

Hydrogen Fuel Quality

Jim Ohi of NREL's presentation on Hydrogen Fuel Quality at the 2007 DOE Hydrogen Program Annual Merit Review and Peer Evaluation on May 15-18, 2007 in Arlington, Virginia.
Date: May 17, 2007
Creator: Ohi, J.
Object Type: Presentation
System: The UNT Digital Library

Macro-System Model

None
Date: May 17, 2007
Creator: Ruth, M.
Object Type: Presentation
System: The UNT Digital Library
METHODOLOGY FOR THE NUMBER OF FILTERS NEEDED IN A WASTE BOX (open access)

METHODOLOGY FOR THE NUMBER OF FILTERS NEEDED IN A WASTE BOX

Waste in large waste boxes can generate volatile organic compounds (VOCs) and hydrogen. These waste boxes may or may not have flow paths out of them (although it is believed that most do). These boxes will be retrieved, sampled, and then coated with polyurea. After coating, filters will be installed in the box to keep the concentration of VOCs and hydrogen acceptably low. The MDSA requires that a vent path must be protected during application of the polyurea coating. If the box has been sampled then it is vented and the vent path must be protected. This report provides a model in which the user inputs the free volume of the waste box, sample concentration (ppm of total VOC or volume fraction hydrogen) along with the number of filters to be placed into the waste box lid. Using this information, the model provides an estimate of concentration vs. time or the number of filters needed to reduce the concentration by a specified fraction. If the equations from this report are placed into spreadsheets which are then used to demonstrate TSR compliance, the spreadsheets must come under the Software QA Plan for such documents. Chapters 2 and 3 present the theory. …
Date: May 17, 2007
Creator: MARUSICH, R.M.
Object Type: Report
System: The UNT Digital Library
Model-based Layer Estimation using a Hybrid Genetic/Gradient Search Optimization Algorithm (open access)

Model-based Layer Estimation using a Hybrid Genetic/Gradient Search Optimization Algorithm

A particle swarm optimization (PSO) algorithm is combined with a gradient search method in a model-based approach for extracting interface positions in a one-dimensional multilayer structure from acoustic or radar reflections. The basic approach is to predict the reflection measurement using a simulation of one-dimensional wave propagation in a multi-layer, evaluate the error between prediction and measurement, and then update the simulation parameters to minimize the error. Gradient search methods alone fail due to the number of local minima in the error surface close to the desired global minimum. The PSO approach avoids this problem by randomly sampling the region of the error surface around the global minimum, but at the cost of a large number of evaluations of the simulator. The hybrid approach uses the PSO at the beginning to locate the general area around the global minimum then switches to the gradient search method to zero in on it. Examples of the algorithm applied to the detection of interior walls of a building from reflected ultra-wideband radar signals are shown. Other possible applications are optical inspection of coatings and ultrasonic measurement of multilayer structures.
Date: May 17, 2007
Creator: Chambers, D.; Lehman, S. & Dowla, F.
Object Type: Article
System: The UNT Digital Library

PHEV Energy Storage and Drive Cycle Impacts

Plug-in Hybrid vehicles energy storage and drive cycle impacts, presented at the 7th Advanced Automotive Battery Conference.
Date: May 17, 2007
Creator: Markel, T. & Pesaran, A.
Object Type: Presentation
System: The UNT Digital Library

Photoelectrochemical Water Systems for H2 Production

This Photoelectrochemical Water Systems for Hydrogen Production presentation by the National Renewable Energy Laboratory's John Turner was given at the DOE Hydrogen Program's 2007 Annual Merit Review.
Date: May 17, 2007
Creator: Turner, J. A.; Deutsch, T.; Head, J. & Vallett, P.
Object Type: Presentation
System: The UNT Digital Library
PHYSICAL AND CHEMICAL MEASUREMENTS NEEDED TO SUPPORT DISPOSITION OFSAVANNAH RIVER SITE RADIOACTIVE HIGH LEVEL WASTE SLUDGE (open access)

PHYSICAL AND CHEMICAL MEASUREMENTS NEEDED TO SUPPORT DISPOSITION OFSAVANNAH RIVER SITE RADIOACTIVE HIGH LEVEL WASTE SLUDGE

Radioactive high level waste (HLW) sludge generated as a result of decades of production and manufacturing of plutonium, tritium and other nuclear materials is being removed from storage tanks and processed into a glass waste-form for permanent disposition at the Federal Repository. Characterization of this HLW sludge is a prerequisite for effective planning and execution of sludge disposition activities. The radioactivity of HLW makes sampling and analysis of the sludge very challenging, as well as making opportunities to perform characterization rare. In order to maximize the benefit obtained from sampling and analysis, a recommended list of physical property and chemical measurements has been developed. This list includes distribution of solids (insoluble and soluble) and water; densities of insoluble solids, interstitial solution, and slurry rheology (yield stress and consistency); mineral forms of solids; and primary elemental and radioactive constituents. Sampling requirements (number, type, volume, etc.), sample preparation techniques, and analytical methods are discussed in the context of pros and cons relative to end use of the data. Generation of useful sample identification codes and entry of results into a centralized database are also discussed.
Date: May 17, 2007
Creator: Hamm, B
Object Type: Article
System: The UNT Digital Library
Plant-Wide Energy Efficiency Assessment at the Arizona Portland Cement Plant in Rillito, Arizona (open access)

Plant-Wide Energy Efficiency Assessment at the Arizona Portland Cement Plant in Rillito, Arizona

A Department of Energy Plant-wide Assessment was undertaken by Arizona Portland Cement (APC) beginning in May 2005. The assessment was performed at APC’s cement production facility in Rillito, Arizona. The assessment included a compressed air evaluation along with a detailed process audit of plant operations and equipment. The purpose of this Energy Survey was to identify a series of energy cost savings opportunities at the Plant, and provide preliminary cost and savings estimates for the work. The assessment was successful in identifying projects that could provide annual savings of over $2.7 million at an estimated capital cost of $4.3 million. If implemented, these projects could amount to a savings of over 4.9 million kWh/yr and 384,420 MMBtu/year.
Date: May 17, 2007
Creator: Stephen J. Coppinger, P.E. & Bruce Colburn, Ph.D., P.E., CEM
Object Type: Report
System: The UNT Digital Library

Quantifying Consumer Sensitivity to Hydrogen Refueling Station Coverage

This presentation by Cory Welch at the 2007 DOE Hydrogen Program Annual Merit Review Meeting focuses on consumer sensitivity to hydrogen refueling station coverage.
Date: May 17, 2007
Creator: Welch, C.
Object Type: Presentation
System: The UNT Digital Library
Thermal Effects on Thin Laser-Peened Ferritic-Martensitic Samples (open access)

Thermal Effects on Thin Laser-Peened Ferritic-Martensitic Samples

None
Date: May 17, 2007
Creator: Caro, M.; Zalesky, T.; Hosemann, P.; El-dasher, B. S.; Halsey, W. G. & Stuart, B.
Object Type: Report
System: The UNT Digital Library
UTILIZING STATISTICS TO DETERMINE HOW MUCH SAMPLING AND ANALYSISIS WARRANTED TO SUPPORT SAVANNAH RIVER SITEHIGH LEVEL WASTE SLUDGE BATCH PREPARATION (open access)

UTILIZING STATISTICS TO DETERMINE HOW MUCH SAMPLING AND ANALYSISIS WARRANTED TO SUPPORT SAVANNAH RIVER SITEHIGH LEVEL WASTE SLUDGE BATCH PREPARATION

Accelerated cleanup initiatives at the SRS include expediting radioactive sludge processing. Sludge is the highest risk component of waste since it contains the highest concentrations of long-lived radionuclides. The sludge is staged into ''batches'' that are then the feed material to the Defense Waste Processing Facility (DWPF) which vitrifies the waste into a safe form for permanent disposal. The preparation of each batch includes sampling and analysis of the slurried material. The results of the characterization are used as the bases for batch blending and processing decisions. Uncertainty is inherent in the information used for planning. There is uncertainty in the quantity of sludge contained in a tank, the waste composition, and the waste physical properties. The goal of this analysis is to develop the basis for the number of physical samples that should be taken from the slurried waste tank and the number of replicates of laboratory measurements that should be performed in order to achieve a specified uncertainty level. Recommendations for sampling and analysis strategies are made based on the results of the analysis.
Date: May 17, 2007
Creator: Hamm, B
Object Type: Article
System: The UNT Digital Library