Angle-resolved photoemission spectroscopy (ARPES) studies of cuprate superconductors (open access)

Angle-resolved photoemission spectroscopy (ARPES) studies of cuprate superconductors

This dissertation is comprised of three different angle-resolved photoemission spectroscopy (ARPES) studies on cuprate superconductors. The first study compares the band structure from two different single layer cuprates Tl{sub 2}Ba{sub 2}CuO{sub 6+{delta}} (Tl2201) T{sub c,max} {approx} 95 K and (Bi{sub 1.35}Pb{sub 0.85})(Sr{sub 1.47}La{sub 0.38})CuO{sub 6+{delta}} (Bi2201) T{sub c,max} {approx} 35 K. The aim of the study was to provide some insight into the reasons why single layer cuprate's maximum transition temperatures are so different. The study found two major differences in the band structure. First, the Fermi surface segments close to ({pi},0) are more parallel in Tl2201 than in Bi2201. Second, the shadow band usually related to crystal structure is only present in Bi2201, but absent in higher T{sub c} Tl2201. The second study looks at the different ways of doping Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+{delta}} (Bi2212) in-situ by only changing the post bake-out vacuum conditions and temperature. The aim of the study is to systematically look into the generally overlooked experimental conditions that change the doping of a cleaved sample in ultra high vacuum (UHV) experiments. The study found two major experimental facts. First, in inadequate UHV conditions the carrier concentration of Bi2212 increases with time, due to the …
Date: December 15, 2010
Creator: Palczewski, Ari Deibert
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Magnetic nanoparticles for applications in oscillating magnetic field (open access)

Magnetic nanoparticles for applications in oscillating magnetic field

Enzymatic and thermochemical catalysis are both important industrial processes. However, the thermal requirements for each process often render them mutually exclusive: thermochemical catalysis requires high temperature that denatures enzymes. One of the long-term goals of this project is to design a thermocatalytic system that could be used with enzymatic systems in situ to catalyze reaction sequences in one pot; this system would be useful for numerous applications e.g. conversion of biomass to biofuel and other commodity products. The desired thermocatalytic system would need to supply enough thermal energy to catalyze thermochemical reactions, while keeping the enzymes from high temperature denaturation. Magnetic nanoparticles are known to generate heat in an oscillating magnetic field through mechanisms including hysteresis and relaxational losses. We envisioned using these magnetic nanoparticles as the local heat source embedded in sub-micron size mesoporous support to spatially separate the particles from the enzymes. In this study, we set out to find the magnetic materials and instrumental conditions that are sufficient for this purpose. Magnetite was chosen as the first model magnetic material in this study because of its high magnetization values, synthetic control over particle size, shape, functionalization and proven biocompatibility. Our experimental designs were guided by a series …
Date: December 15, 2010
Creator: Peeraphatdit, Chorthip
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Measurements of Exclusive B \to Xc l nubar Decays and |Vcb| at BaBar (open access)

Measurements of Exclusive B \to Xc l nubar Decays and |Vcb| at BaBar

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Date: December 15, 2011
Creator: Pegna, David Lopes
Object Type: Article
System: The UNT Digital Library
Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System (open access)

Isotopic evidence for the infiltration of mantle and metamorphic CO2-H2O fluids from below in faulted rocks from the San Andreas Fault System

To characterize the origin of the fluids involved in the San Andreas Fault (SAF) system, we carried out an isotope study of exhumed faulted rocks from deformation zones, vein fillings and their hosts and the fluid inclusions associated with these materials. Samples were collected from segments along the SAF system selected to provide a depth profile from upper to lower crust. In all, 75 samples from various structures and lithologies from 13 localities were analyzed for noble gas, carbon, and oxygen isotope compositions. Fluid inclusions exhibit helium isotope ratios ({sup 3}He/{sup 4}He) of 0.1-2.5 times the ratio in air, indicating that past fluids percolating through the SAF system contained mantle helium contributions of at least 35%, similar to what has been measured in present-day ground waters associated with the fault (Kennedy et al., 1997). Calcite is the predominant vein mineral and is a common accessory mineral in deformation zones. A systematic variation of C- and O-isotope compositions of carbonates from veins, deformation zones and their hosts suggests percolation by external fluids of similar compositions and origin with the amount of fluid infiltration increasing from host rocks to vein to deformation zones. The isotopic trend observed for carbonates in veins and …
Date: December 15, 2010
Creator: Pili, E.; Kennedy, B.M.; Conrad, M.E. & Gratier, J.-P.
Object Type: Article
System: The UNT Digital Library
Microstructures and oxidation behavior of some Molybdenum based alloys (open access)

Microstructures and oxidation behavior of some Molybdenum based alloys

The advent of Ni based superalloys revolutionized the high temperature alloy industry. These materials are capable of operating in extremely harsh environments, comprising of temperatures around 1050 C, under oxidative conditions. Demands for increased fuel efficiency, however, has highlighted the need for materials that can be used under oxidative conditions at temperatures in excess of 1200 C. The Ni based superalloys are restricted to lower temperatures due to the presence of a number of low melting phases that melt in the 1250 - 1450 C, resulting in softening of the alloys above 1000 C. Therefore, recent research directions have been skewed towards exploring and developing newer alloy systems. This thesis comprises a part of such an effort. Techniques for rapid thermodynamic assessments were developed and applied to two different systems - Mo-Si alloys with transition metal substitutions (and this forms the first part of the thesis) and Ni-Al alloys with added components for providing high temperature strength and ductility. A hierarchical approach towards alloy design indicated the Mo-Ni-Al system as a prospective candidate for high temperature applications. Investigations on microstructures and oxidation behavior, under both isothermal and cyclic conditions, of these alloys constitute the second part of this thesis. It …
Date: December 15, 2010
Creator: Ray, Pratik Kumar
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Checklist for Transition to New Highway Fuel(s). (open access)

Checklist for Transition to New Highway Fuel(s).

Transportation is vital to the U.S. economy and society. As such, U.S. Presidents have repeatedly stated that the nation needs to reduce dependence on petroleum, especially for the highway transportation sector. Throughout history, highway transportation fuel transitions have been completed successfully both in United States and abroad. Other attempts have failed, as described in Appendix A: Historical Highway Fuel Transitions. Planning for a transition is critical because the changes can affect our nation's ability to compete in the world market. A transition will take many years to complete. While it is tempting to make quick decisions about the new fuel(s) of choice, it is preferable and necessary to analyze all the pertinent criteria to ensure that correct decisions are made. Doing so will reduce the number of changes in highway fuel(s). Obviously, changes may become necessary because of occurrences such as significant technology breakthroughs or major world events. With any and all of the possible transitions to new fuel(s), the total replacement of gasoline and diesel fuels is not expected. These conventional fuels are envisioned to coexist with the new fuel(s) for decades, while the revised fuel and vehicle infrastructures are implemented. The transition process must analyze the needs of …
Date: December 15, 2011
Creator: Risch, C. & Santini, D.J. (Energy Systems)
Object Type: Report
System: The UNT Digital Library
Content Analysis for Proactive Protective Intelligence (open access)

Content Analysis for Proactive Protective Intelligence

The aim of this paper is to outline a plan for developing and validating a Proactive Protective Intelligence approach that prevents targeted violence through the analysis and assessment of threats overtly or covertly expressed in abnormal communications to USSS protectees.
Date: December 15, 2010
Creator: Sanfilippo, Antonio P.
Object Type: Report
System: The UNT Digital Library
Extending the frontiers of mass spectrometric instrumentation and methods (open access)

Extending the frontiers of mass spectrometric instrumentation and methods

The focus of this dissertation is two-fold: developing novel analysis methods using mass spectrometry and the implementation and characterization of a novel ion mobility mass spectrometry instrumentation. The novel mass spectrometry combines ion trap for ion/ion reactions coupled to an ion mobility cell. The long term goal of this instrumentation is to use ion/ion reactions to probe the structure of gas phase biomolecule ions. The three ion source - ion trap - ion mobility - qTOF mass spectrometer (IT - IM - TOF MS) instrument is described. The analysis of the degradation products in coal (Chapter 2) and the imaging plant metabolites (Appendix III) fall under the methods development category. These projects use existing commercial instrumentation (JEOL AccuTOF MS and Thermo Finnigan LCQ IT, respectively) for the mass analysis of the degraded coal products and the plant metabolites, respectively. The coal degradation paper discusses the use of the DART ion source for fast and easy sample analysis. The sample preparation consisted of a simple 50 fold dilution of the soluble coal products in water and placing the liquid in front of the heated gas stream. This is the first time the DART ion source has been used for analysis of …
Date: December 15, 2010
Creator: Schieffer, Gregg
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Energy Saving Melting and Revert Reduction Technology: Melting Efficiency in Die Casting Operations (open access)

Energy Saving Melting and Revert Reduction Technology: Melting Efficiency in Die Casting Operations

This project addressed multiple aspects of the aluminum melting and handling in die casting operations, with the objective of increasing the energy efficiency while improving the quality of the molten metal. The efficiency of melting has always played an important role in the profitability of aluminum die casting operations. Consequently, die casters need to make careful choices in selecting and operating melting equipment and procedures. The capital cost of new melting equipment with higher efficiency can sometimes be recovered relatively fast when it replaces old melting equipment with lower efficiency. Upgrades designed to improve energy efficiency of existing equipment may be well justified. Energy efficiency is however not the only factor in optimizing melting operations. Melt losses and metal quality are also very important. Selection of melting equipment has to take into consideration the specific conditions at the die casting shop such as availability of floor space, average quantity of metal used as well as the ability to supply more metal during peaks in demand. In all these cases, it is essential to make informed decisions based on the best available data.
Date: December 15, 2012
Creator: Schwam, David
Object Type: Report
System: The UNT Digital Library
The Earned Income Tax Credit (EITC): An Overview (open access)

The Earned Income Tax Credit (EITC): An Overview

The Earned Income Tax Credit began in 1975 as a temporary program to return a portion of the Social Security taxes paid by lower-income taxpayers, and was made permanent in 1978. In the 1990s, the program because a major component of federal efforts to reduce poverty, and is now the largest anti-poverty entitlement program. This report contains information on eligibility for the program, credit amount, participation, interaction with other tax provisions, issues, compliance, and more as related to the Earned Income Tax Credit.
Date: December 15, 2010
Creator: Scott, Christine
Object Type: Report
System: The UNT Digital Library
Enrichment, isolation and characterization of fungi tolerant to 1-ethyl-3-methylimidazolium acetate (open access)

Enrichment, isolation and characterization of fungi tolerant to 1-ethyl-3-methylimidazolium acetate

This work aims to characterize microbial tolerance to 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), ionic liquid that has emerged as a novel biomass pretreatment for lignocellulosic biomass. Enrichment experiments performed using inocula treated with [C2mim][OAc] under solid and liquid cultivation yielded fungal populationsdominated by Aspergilli. Ionic liquid-tolerant Aspergillus isolates from these enrichments were capable of growing in a radial plate growth assay in the presence of 10% [C2mim][OAc]. When a [C2mim][OAc]-tolerant Aspergillus fumigatus strain was grown in the presence of switchgrass, endoglucanases and xylanases were secreted that retained residual enzymatic activity in the presence of 20% [C2mim][OAc]. The results of the study suggest tolerance to ionic liquids is a general property of Aspergilli. Tolerance to an industrially important ionic liquid was discovered in a fungal genera that is widely used in biotechnology, including biomass deconstruction.
Date: December 15, 2010
Creator: Singer, S.W.; Reddy, A. P.; Gladden, J. M.; Guo, H.; Hazen, T.C.; Simmons, B. A. et al.
Object Type: Article
System: The UNT Digital Library
TANKS 18 AND 19-F EQUIPMENT GROUT FILL MATERIAL EVALUATION AND RECOMMENDATIONS (open access)

TANKS 18 AND 19-F EQUIPMENT GROUT FILL MATERIAL EVALUATION AND RECOMMENDATIONS

The United States Department of Energy (US DOE) intends to remove Tanks 18-F and 19-F at the Savannah River Site (SRS) from service. The high-level waste (HLW) tanks have been isolated from the F-area Tank Farm (FTF) facilities and will be filled with cementitious grout for the purpose of: (1) physically stabilizing the empty volumes in the tanks, (2) limiting/eliminating vertical pathways from the surface to residual waste on the bottom of the tanks, (3) providing an intruder barrier, and (4) providing an alkaline, chemical reducing environment within the closure boundary to limit solubility of residual radionuclides. Bulk waste and heel waste removal equipment will remain in Tanks 18-F and 19-F when the tanks are closed. This equipment includes: mixer pumps, transfer pumps, transfer jets, equipment support masts, sampling masts and dip tube assemblies. The current Tank 18-F and 19-F closure strategy is to grout the internal void spaces in this equipment to eliminate fast vertical pathways and slow water infiltration to the residual material on the tank floor. This report documents the results of laboratory testing performed to identify a grout formulation for filling the abandoned equipment in Tanks 18-F and 19-F. The objective of this work was to …
Date: December 15, 2011
Creator: Stefanko, D. & Langton, C.
Object Type: Report
System: The UNT Digital Library
Army Corps Fiscal Challenges: Frequently Asked Questions (open access)

Army Corps Fiscal Challenges: Frequently Asked Questions

This report lists and answers the frequently asked questions on the army corps fiscal challenges.
Date: December 15, 2011
Creator: Stern, Charles V. & Carter, Nicole T.
Object Type: Report
System: The UNT Digital Library
Developing new optical imaging techniques for single particle and molecule tracking in live cells (open access)

Developing new optical imaging techniques for single particle and molecule tracking in live cells

Differential interference contrast (DIC) microscopy is a far-field as well as wide-field optical imaging technique. Since it is non-invasive and requires no sample staining, DIC microscopy is suitable for tracking the motion of target molecules in live cells without interfering their functions. In addition, high numerical aperture objectives and condensers can be used in DIC microscopy. The depth of focus of DIC is shallow, which gives DIC much better optical sectioning ability than those of phase contrast and dark field microscopies. In this work, DIC was utilized to study dynamic biological processes including endocytosis and intracellular transport in live cells. The suitability of DIC microscopy for single particle tracking in live cells was first demonstrated by using DIC to monitor the entire endocytosis process of one mesoporous silica nanoparticle (MSN) into a live mammalian cell. By taking advantage of the optical sectioning ability of DIC, we recorded the depth profile of the MSN during the endocytosis process. The shape change around the nanoparticle due to the formation of a vesicle was also captured. DIC microscopy was further modified that the sample can be illuminated and imaged at two wavelengths simultaneously. By using the new technique, noble metal nanoparticles with different …
Date: December 15, 2010
Creator: Sun, Wei
Object Type: Thesis or Dissertation
System: The UNT Digital Library
Texas Commission on Environmental Quality Annual Report of Nonfinancial Data: 2016 (open access)

Texas Commission on Environmental Quality Annual Report of Nonfinancial Data: 2016

Report containing non-financial data for the Texas Commission on Environmental Quality during fiscal year 2016, including information on nonfinancial data such as various progress reports, schedules, and fees, space occupied, and itemized and vehicle purchases.
Date: December 15, 2016
Creator: Texas Commission on Environmental Quality
Object Type: Report
System: The Portal to Texas History
Texas Lottery Commission Annual Financial Report: 2011, with Auditor's Report (open access)

Texas Lottery Commission Annual Financial Report: 2011, with Auditor's Report

Annual financial report of the Texas Lottery Commission for fiscal year 2011, providing statements of assets, expenditures, revenues, and other relevant data as well as the report of an independent auditor.
Date: December 15, 2011
Creator: Texas Lottery Commission
Object Type: Report
System: The Portal to Texas History
Texas Attorney General Opinion: GA-0897 (open access)

Texas Attorney General Opinion: GA-0897

Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, Greg Abbott, regarding a legal question submitted for clarification: Whether the use of the term “Nationally Certified School Psychologist” by a Licensed Specialist in School Psychology is a violation of the Psychologists’ Licensing Act (RQ-0947-GA)
Date: December 15, 2011
Creator: Texas. Attorney-General's Office.
Object Type: Text
System: The Portal to Texas History
Texas Attorney General Opinion: GA-0898 (open access)

Texas Attorney General Opinion: GA-0898

Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, Greg Abbott, regarding a legal question submitted for clarification: Whether a member of the El Paso County Ethics Commission who is a practicing attorney or former judge may be appointed to serve as the review officer of a preliminary screening committee (RQ-0978-GA)
Date: December 15, 2011
Creator: Texas. Attorney-General's Office.
Object Type: Text
System: The Portal to Texas History
Texas Attorney General Opinion: GA-0899 (open access)

Texas Attorney General Opinion: GA-0899

Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, Greg Abbott, regarding a legal question submitted for clarification; Jurisdiction of the Texas State Cemetary over a state highway, the majority of which is located within the boundaries of the Cemetary (RQ-0979-GA)
Date: December 15, 2011
Creator: Texas. Attorney-General's Office.
Object Type: Text
System: The Portal to Texas History
Texas Attorney General Opinion: GA-1094 (open access)

Texas Attorney General Opinion: GA-1094

Document issued by the Office of the Attorney General of Texas in Austin, Texas, providing an interpretation of Texas law. It provides the opinion of the Texas Attorney General, Greg Abbott, regarding a legal question submitted for clarification: Disposition of surplus property purchased with proceeds of the sheriffs commissary account (RQ-1207-GA).
Date: December 15, 2014
Creator: Texas. Attorney-General's Office.
Object Type: Text
System: The Portal to Texas History
Texas Comptroller of Public Accounts Annual Report of Nonfinancial Data: 2017 (open access)

Texas Comptroller of Public Accounts Annual Report of Nonfinancial Data: 2017

Report containing non-financial data for the Texas Office of the Comptroller of Public Accounts during fiscal year 2017, including information on occupied spaces, strategic plan updates, vehicles purchased, and other related topics and documentation.
Date: December 15, 2017
Creator: Texas. Comptroller's Office.
Object Type: Report
System: The Portal to Texas History
Texas Department of Licensing and Regulation Annual Report of Nonfinancial Data: 2011 (open access)

Texas Department of Licensing and Regulation Annual Report of Nonfinancial Data: 2011

Annual report on nonfinancial data from the Texas Department of Licensing and Regulation for fiscal year 2011, including information about space usage, fees, progress on their HUB (historically underutilized business) plan, state-owned vehicles, environmentally-sensitive purchases, and other relevant data from the year.
Date: December 15, 2011
Creator: Texas. Department of Licensing and Regulation.
Object Type: Report
System: The Portal to Texas History
Texas Department of Transportation Annual Financial Report: 2017 (open access)

Texas Department of Transportation Annual Financial Report: 2017

Annual financial report of the Texas. Department of Transportation documenting income, expenditures, and other relevant financial information for fiscal year 2017.
Date: December 15, 2017
Creator: Texas. Department of Transportation.
Object Type: Report
System: The Portal to Texas History
Interim News, Volume 82, Number 1, December 2011 (open access)

Interim News, Volume 82, Number 1, December 2011

Newsletter of the Texas House of Representative House Research Organization, addressing law reform in Texas and the activities of the agency.
Date: December 15, 2011
Creator: Texas. Legislature. House of Representatives. Research Organization.
Object Type: Journal/Magazine/Newsletter
System: The Portal to Texas History