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U.S. International ESL Students' Experiences with and Perceptions of Utilizing Mobile Technologies for English Learning (open access)

U.S. International ESL Students' Experiences with and Perceptions of Utilizing Mobile Technologies for English Learning

The purpose of this research was to examine ESL (English as a second language) students' current use of their mobile phones for English skill building activities outside of class in a U.S. school setting. In addition, this research reported on students' perceptions of the potential benefits of using smartphones in class for English learning. Also learners' current English related activities using mobile devices and time duration of using different phone features were studied. The literature review included smartphones, computer education, mobile learning, mobile assisted language learning (MALL), computer assisted language learning (CALL), theories of second language learning, second language learner attributes and the use of smartphones outside the classroom. An electronic survey was used to collect the quantitative data which were analyzed by descriptive and inferential statistics. The results concluded that students used mobile applications on a daily basis to read and write email, read books and news, check a dictionary, talk, text and video chat. Students used mobile phones outside of class to improve the English skills listed in the survey and the same participants perceived the potential benefits of using smartphones in class for the same English skills. Among the English skills, vocabulary exercises, finding example sentences of …
Date: December 2017
Creator: Zhu, Shanyuan
System: The UNT Digital Library
Preservice Teachers' Beliefs about Writing and Their Plans to Teach Writing: The Apprenticeship of Observation (open access)

Preservice Teachers' Beliefs about Writing and Their Plans to Teach Writing: The Apprenticeship of Observation

Preservice teachers (PSTs) bring a plethora of knowledge and experiences to their educator preparation courses. The PSTs have also formed ideas about how to teach based on their observations during the thousands of hours they spent as students in the classroom from kindergarten through high school graduation. This phenomenon, coined by Lortie, is called the apprenticeship of observation. Past research has focused on the apprenticeship of observation in general while neglecting to specifically explore how this phenomenon influences PSTs in regards to writing. Guiding this study were three research questions: (1) what are the PSTs' beliefs about writing instruction and themselves as writers, (2) how have PSTs' experiences as students affected their beliefs about themselves as writers, and (3) how do PSTs' experiences as students influence their plans to teach writing? After conducting a thematic analysis, there are four findings that stemmed from the data. First, PSTs come to their educator preparation programs with beliefs about themselves as writers. Particularly, the PSTs believe they are either writers or non-writers, Next, PSTs believe that writing instruction should be high-quality and foster student interest. Additionally, data suggested that PSTs' past experiences as students in a writing classroom influenced the PSTs' beliefs. Particularly, …
Date: December 2017
Creator: Thompson, Emily Kyle
System: The UNT Digital Library
The Experience of Language Use for Second Generation, Bilingual, Mexican American, 5th Grade Students (open access)

The Experience of Language Use for Second Generation, Bilingual, Mexican American, 5th Grade Students

There is a paucity of research regarding language use among bilingual clients, particularly with Latino children. In order to provide culturally sensitive counseling for bilingual, Spanish-speaking, Latino children it is important to understand their experience of language use. The purpose of this study was to investigate how second generation, bilingual, Mexican American, 5th grade students experience language use in the two languages with which they communicate. I employed a phenomenological method to data collection and analysis and conducted semi-structured individual and group interviews with three boys and five girls (N = 8). Analysis of the individual and group interviews yielded four main structures: (a) dominant language determined perception of developing dual selves, (b) speaking two languages useful in language brokering and upward mobility, (c) dominant language determined experience of language use, and (d) language use and aspects of the complementarity principle. Findings from this study suggest that bilingual Latino children experience language brokering for their parents as difficult, speaking two languages as useful regarding upward mobility, and that their dominant language influences various aspects of their daily experiences such as with whom and where they use each language. Limitations to this research include insufficient time building rapport with participants and …
Date: December 2017
Creator: Paz, Michael
System: The UNT Digital Library
Catalysts of Women's Success in Academic STEM: A Feminist Poststructural Analysis (open access)

Catalysts of Women's Success in Academic STEM: A Feminist Poststructural Analysis

This study analyzes senior women faculty's discourses about personal and professional experiences they believe contributed to their advancement in academic careers in science, technology, engineering, and mathematics (STEM). The purpose of the study is to understand factors that activate women's success in STEM disciplines where women's representation has not yet attained critical mass. A poststructuralist emphasis on complexity and changing nature of power relations offers a framework that illuminates the ways in which elite women navigate social inequalities, hierarchies of power, and non-democratic practices. Feminist poststructural discourse analysis (FPDA) methods allow analysis of women's talk about their experiences in order to understand the women's complex, shifting positions. Eight female tenured full professors of STEM at research-focused universities in the United States participated in the study. Data sources were in-depth semi-structured interviews, a demographic survey, and curricula vitae. Findings will help shape programs and policies aimed at increasing female representation and promoting achievement at senior levels in academic STEM fields.
Date: December 2017
Creator: Mullet, Dianna Rose
System: The UNT Digital Library
Shear and Compression Strength of Cold-formed Steel Clip Angles Subjected to Different Screw Patterns (open access)

Shear and Compression Strength of Cold-formed Steel Clip Angles Subjected to Different Screw Patterns

This thesis presents experiments and numerical analysis of the cold-formed steel clip angle in three different limit states which are shear, compression, and combination of the screw connection. A previous cold-formed steel clip angle test program (which is Phase 1) developed design methods for clip angle. Therefore, the object of this thesis is to further investigate the behavior and design methods of loading-bearing cold-formed steel clip angles under different screw pattern. For each limit state, a test program was conducted to investigate the behavior, strength, and deflection of the clip angle. The test result were compared with previous CFS clip angle design method. Amending existing CFS clip angle method were developed by each of the four limit states studied in this project.
Date: December 2017
Creator: Yan, Zhishan
System: The UNT Digital Library
Evaluation of Call Mobility on Network Productivity in Long Term Evolution Advanced (LTE-A) Femtocells (open access)

Evaluation of Call Mobility on Network Productivity in Long Term Evolution Advanced (LTE-A) Femtocells

The demand for higher data rates for indoor and cell-edge users led to evolution of small cells. LTE femtocells, one of the small cell categories, are low-power low-cost mobile base stations, which are deployed within the coverage area of the traditional macro base station. The cross-tier and co-tier interferences occur only when the macrocell and femtocell share the same frequency channels. Open access (OSG), closed access (CSG), and hybrid access are the three existing access-control methods that decide users' connectivity to the femtocell access point (FAP). We define a network performance function, network productivity, to measure the traffic that is carried successfully. In this dissertation, we evaluate call mobility in LTE integrated network and determine optimized network productivity with variable call arrival rate in given LTE deployment with femtocell access modes (OSG, CSG, HYBRID) for a given call blocking vector. The solution to the optimization is maximum network productivity and call arrival rates for all cells. In the second scenario, we evaluate call mobility in LTE integrated network with increasing femtocells and maximize network productivity with variable femtocells distribution per macrocell with constant call arrival rate in uniform LTE deployment with femtocell access modes (OSG, CSG, HYBRID) for a given …
Date: December 2017
Creator: Sawant, Uttara
System: The UNT Digital Library
The Effectiveness of Peer Mentoring with High School Student Mentors and Child Mentees (open access)

The Effectiveness of Peer Mentoring with High School Student Mentors and Child Mentees

This randomized, controlled study examined the effectiveness of two mentoring programs, child mentor relationship training (CMRT) and peer assistance and leadership (PAL®), on high school mentor empathic behaviors and child mentee behavior problems. Participants were 60 young, at-risk students (61.7% male; 38.3% Hispanic/Latino/a, 31.7% Caucasian, 21.7% African American, 8.3% biracial) and 30 high school students (53.3% male; 66.7% Caucasian, 26.7% Hispanic/Latino/a, 0.03% African American, 0.03% Asian). Mentors and mentees were randomly assigned to CMRT or PAL®, which was treatment as usual in the participating school district. Results from 2 (group) by 2 (time) repeated measures ANOVAs indicated compared to the PAL® treatment group over time, mentors in the CMRT group demonstrated statistically significant improvement in empathic behaviors with a large treatment effect, as rated by independent observers. Analysis revealed a moderate treatment effect with CMRT group mentee behavior problems, but the difference was not statistically significant between treatment groups over time. Further analysis revealed the CMRT group demonstrated statistically significant reductions in behavior problems from pre- to post-test with a very large treatment effect. Overall, findings support CMRT as a promising school-based intervention for at-risk young children that potentially increases school counselor efficiency.
Date: December 2017
Creator: Dafoe, Eric C.
System: The UNT Digital Library
Phylogenetic and Functional Characterization of Cotton (Gossypium hirsutum) CENTRORADIALIS/TERMINAL FLOWER1/SELF-PRUNING Genes (open access)

Phylogenetic and Functional Characterization of Cotton (Gossypium hirsutum) CENTRORADIALIS/TERMINAL FLOWER1/SELF-PRUNING Genes

Plant architecture is an important agronomic trait driven by meristematic activities. Indeterminate meristems set repeating phytomers while determinate meristems produce terminal structures. The centroradialis/terminal flower1/self pruning (CETS) gene family modulates architecture by controlling determinate and indeterminate growth. Cotton (G. hirsutum) is naturally a photoperiodic perennial cultivated as a day-neutral annual. Management of this fiber crop is complicated by continued vegetative growth and asynchronous fruit set. Here, cotton CETS genes are phylogenetically and functionally characterized. We identified eight CETS genes in diploid cotton (G. raimondii and G. arboreum) and sixteen in tetraploid G. hirsutum that grouped within the three generally accepted CETS clades: flowering locus T (FT)-like, terminal flower1/self pruning (TFL1/SP)-like, and mother of FT and TFL1 (MFT)-like. Over-expression of single flower truss (GhSFT), the ortholog to Arabidopsis FT, accelerates the onset of flowering in Arabidopsis Col-0. In mutant rescue analysis, this gene driven by its native promoter rescues the ft-10 late flowering phenotype. GhSFT upstream sequence was used to drive expression of the uidA reporter gene. As anticipated, GUS accumulated in the vasculature of Arabidopsis leaves. Cotton has five TFL1-like genes, all of which delay flowering when ectopically expressed in Arabidopsis; the strongest phenotypes fail to produce functional flowers. Three …
Date: December 2017
Creator: Prewitt, Sarah F.
System: The UNT Digital Library
Artscapes: Community Perceptions of City Beautification through Murals in Denton, Texas (open access)

Artscapes: Community Perceptions of City Beautification through Murals in Denton, Texas

Keep Denton Beautiful (KDB) is inspired by Keep America Beautiful's model of community engagement to create a clean, beautiful, and vibrant city. The community mural initiative, Artscapes, aims to enliven public spaces, abate graffiti, and inspire community members to keep Denton, Texas, clean and beautiful. The goals of this research project are to understand the impact of Artscapes initiative, community perceptions of public art, and find ways KDB can better align future mural projects with the needs and desires of community members. By talking to artists that have worked with KDB, members of the mural art committee, and community members from the neighborhoods that have existing murals, this research provides input from these three populations to continue creating public art for the Denton community. I discuss the context of my work through Lefebvre's concept of "Right to the City," Rafael Schacter's opposition between sanctioned and non-sanctioned murals, Bourdieu's concept of symbolic and social capital, and David Harvey's work on neoliberalism and the entrepreneurial city.
Date: December 2017
Creator: Robertson, Lindsey
System: The UNT Digital Library
An Analytical Perspective of the Developing Aesthetic Concepts in Sergey Prokofiev's Choses en soi, Op. 45 (open access)

An Analytical Perspective of the Developing Aesthetic Concepts in Sergey Prokofiev's Choses en soi, Op. 45

The purpose of this study is to analyze the compositional techniques in Choses en soi op.45, by Sergey Prokofiev, and to explore the new aesthetic concepts he claimed to include in this composition. Through the examination of the compositional elements and discussion of its salient characteristics.
Date: December 2017
Creator: Liu, Tzu-Yi
System: The UNT Digital Library
Considerations for Global Development and Impact using Haiti as a Case Study (open access)

Considerations for Global Development and Impact using Haiti as a Case Study

As the world becomes more connected, issues surrounding sustainable development are coming to the fore of global discussions. This is exemplified in strategies such as the United Nation's Sustainable Development Goals (SDGs), released in 2015, which created a framework for global development that defines specific goals for issues like poverty, climate change, and social justice. To complement the analysis that went into defining the SDGs, capital allocations around the world are becoming more impact focused so that the paradigm of development is shifting from donations to impact investments. The push for impact, however, has led to a homogenization of global challenges like reproductive health and poverty. This, in turn, has led to a standardization of information resulting in agencies designing interventions based on data and information that is misguided because of incorrect assumptions about a specific context. This paper explores how the decision-making mechanisms of global development agencies and investors could apply more anthropological processes to mitigate negative impact. As the development sector becomes more and more standardized, anthropologists can act as translators between affected communities and the institutions deciding how best to help them.
Date: December 2017
Creator: Clerie, Isabelle
System: The UNT Digital Library
The Impact of True Fit® Technology on Millennial Consumer Confidence and Satisfaction in their Online Clothing Purchase (open access)

The Impact of True Fit® Technology on Millennial Consumer Confidence and Satisfaction in their Online Clothing Purchase

This study examines the use of True Fit® technology by millennial consumers and its impact on consumer confidence and satisfaction with respect to online sizing. In the apparel industry, there is a lack of size standards among retailers, and as a result consumers will encounter frequent size variations in their clothing size. Difference sizing technology has been developed to address the sizing issue. One is True Fit® which unlike other sizing technologies, uses mathematical algorithms to compile large amounts of data from designers. The purpose of this study was to analyze consumer confidence and satisfaction after True Fit® has been used to make a sizing decision while online shopping. The technology acceptance model (TAM) was used as the basis for the theoretical framework for this study. TAM explores how current advances in technology are influencing consumers' behaviors and attitudes. The variables studies included perceived ease of use, perceived usefulness, attitude, intent to use True Fit®, confidence and satisfaction. The methodology used in the study is a quantitative method consisting of an online survey and a True Fit® task, where consumers were exposed to True Fit® prior to answering questions about the use of sizing technology. The results of the study …
Date: December 2017
Creator: Parr, Jacqueline Nicole
System: The UNT Digital Library
Using Concurrent Schedules of Reinforcement to Decrease Behavior (open access)

Using Concurrent Schedules of Reinforcement to Decrease Behavior

We manipulated delay and magnitude of reinforcers in two concurrent schedules of reinforcement to decrease a prevalent behavior while increasing another behavior already in the participant's repertoire. The first experiment manipulated delay, implementing a five second delay between the behavior and delivery of reinforcement for a behavior targeted for decrease while no delay was implemented after the behavior targeted for increase. The second experiment manipulated magnitude, providing one piece of food for the behavior targeted for decrease while two pieces of food were provided for the behavior targeted for increase. The experiments used an ABAB reversal design. Results suggest that behavior can be decreased without the use of extinction when contingencies favor the desirable behavior.
Date: December 2017
Creator: Palmer, Ashlyn
System: The UNT Digital Library
Impact of Relational Incongruity on Customer Ownership and Sales Outcome Performance: A Resource-Advantage Theory Approach (open access)

Impact of Relational Incongruity on Customer Ownership and Sales Outcome Performance: A Resource-Advantage Theory Approach

There exists heightened research attention afforded to the pivotal demands - both internal and external - that exist within the salesperson role set. Unprecedented pressures on salespersons to acquire, retain, and build enduring customer relationships to enhance the firm's bottom-line performance coincides with increasing complexities within the work environment. This relevant and timely research introduces an original construct derived from the long-standing attention afforded to relationship selling, relational incongruity that exists within the buyer-seller exchange. Relational incongruity, defined, is the relational tension spawned between the salesperson, the customer, and the firm when situational psychological incongruity exists within the buyer-seller exchange itself. Framed in resource-advantage theory, this research investigates divergent demands and the increasing complexity of sales relationships through the lens of relational incongruity. A research program based on minimizing relational incongruity will augment the sales management and B2B literature by looking at how he salesperson and the customer build strong relationships as well as the antecedents that can undermine these relationships by generating realtional incongruity.
Date: December 2017
Creator: Fergurson, Ricky
System: The UNT Digital Library
Effects of HALSs and Nano-ZnO Worked as UV Stabilizers of Polypropylene (open access)

Effects of HALSs and Nano-ZnO Worked as UV Stabilizers of Polypropylene

This work reports the outdoor weathering performance of ultraviolet (UV)-stabilized polypropylene (PP) products (using PP resins from Encore Wire). Different hindered amine light stabilizers (HALSs) and nano-ZnO were used to stabilize PP-film-based formulations that were exposed under UV light for 6 weeks simulating for in harsh outdoor weather of Dallas, Texas, USA in 2016. Characterization of the exposed PP film products was done in terms of mechanical and friction spectroscopic properties. The PP film formulations were divided into 15 categories based on the type of HALS and nano-ZnO incorporated. This was done to derive meaningful comparison of the various film formulations. Following exposure under UV light, the lifetimes of certain formulations were determined. On the basis of the mechanical and friction properties, it was determined that generally, the HALS or nano-ZnO stabilized PP film give better properties and if those two kinds of UV stabilizers can work together.
Date: December 2017
Creator: Lu, Xinyao
System: The UNT Digital Library
Core-Shell Based Metamaterials: Fabrication Protocol and Optical Properties (open access)

Core-Shell Based Metamaterials: Fabrication Protocol and Optical Properties

The objective of this study is to examine core-shell type plasmonic metamaterials aimed at the development of materials with unique electromagnetic properties. The building blocks of metamaterials under study consist of gold as a metal component, and silica and precipitated calcium carbonate (PCC) as the dielectric media. The results of this study demonstrate important applications of the core-shells including scattering suppression, airborne obscurants made of fractal gold shells, photomodification of the fractal structure providing windows of transparency, and plasmonics core-shell with a gain shell as an active device. Plasmonic resonances of the metallic shells depend on their nanostructure and geometry of the core, which can be optimized for the broadband extinction. Significant extinction from the visible to mid-infrared makes fractal shells very attractive as bandpass filters and aerosolized obscurants. In contrast to the planar fractal films, where the absorption and reflection equally contribute to the extinction, the shells' extinction is caused mainly by the absorption. This work shows that the Mie scattering resonance of a silica core with 780 nm diameter at 560 nm is suppressed by 75% and only partially substituted by the absorption in the shell so that the total transmission is noticeably increased. Effective medium theory supports …
Date: December 2017
Creator: De Silva, Vashista C
System: The UNT Digital Library
The Generation of Recombinant Zea mays Spastin and Katanin Proteins for In Vitro Analysis (open access)

The Generation of Recombinant Zea mays Spastin and Katanin Proteins for In Vitro Analysis

Plant microtubules play essential roles in cell processes such as cell division, cell elongation, and organelle organization. Microtubules are arranged in highly dynamic and ordered arrays, but unlike animal cells, plant cells lack centrosomes. Therefore, microtubule nucleation and organization are governed by microtubule-associated proteins, including a microtubule-severing protein, katanin. Mutant analysis and in vitro characterization has shown that the highly conserved katanin is needed for the organization of the microtubule arrays in Arabidopsis and rice as well as in a variety of animal models. Katanin is a protein complex that is part of the AAA+ family of ATPases. Katanin is composed of two subunits, katanin-p60, a catalytic subunit and katanin-p80, a regulatory subunit. Spastin is another MT-severing protein that was identified on the basis of its homology to katanin. In animal cells, spastin is also needed for microtubule organization, but its functionality has not yet been investigated in plants. To initiate an exploration of the function of katanin-p60 and spastin in Zea mays, my research goal was to generate tools for the expression and purification of maize katanin-p60 and spastin proteins in vitro. Plasmids that express katanin-p60 and spastin with N-terminal GST tags were designed and constructed via In-Fusion® cloning …
Date: December 2017
Creator: Alodailah, Sattam Sonitan
System: The UNT Digital Library
Synthesis and characterization of an N-(2-hydroxyethyl)-ethylenediaminetriacetic acid resin (open access)

Synthesis and characterization of an N-(2-hydroxyethyl)-ethylenediaminetriacetic acid resin

A chelating ion-exchange resin with N-(2-hydroxyethyl)ethylene-diaminetriacetic acid (HEDTA) used as the ligand chemically bonded to XAD-4 by an ester linkage, HEDTA-4, was synthesized. It is stable under normal experimental conditions with the liquid chromatograph. The structure of the resin was confirmed by an infrared spectrum, and by potentiometric titrations. The capacity of the resin was also obtained by potentiometric titration and by a nitrogen analysis. The resin was used to pack a column of 5 mm internal diameter and 5 cm long. The effect of pH on the retention of different metal ions on the resin was studied. It was found that the resin was most selective for chromium(III), copper(II), lead(II), mercury(II), uranium(VI), zirconium(IV) and zinc(II) at a pH of less than 3. Furthermore, the resin proves to be functioning with a chelating mechanism rather than ion-exchange, and it can concentrate trace metal ions in the presence of a large excess of calcium and magnesium. This makes the resin potentially useful for purifying and analyzing drinking water.
Date: October 1, 1977
Creator: Lai, Y. F.
System: The UNT Digital Library
Electron microscopy of hydrocarbon production in parthenium argentatum (guayule) (open access)

Electron microscopy of hydrocarbon production in parthenium argentatum (guayule)

The electron microscope was used to study the biological processes involved in hydrocarbon production. The little desert shrub Guayule (Parthenium argentatum) was selected for study. This shrub can produce hydrocarbons (rubber) in concentrations up to 1/4 of its dry weight. It grows on semi-arid land and has been extensively studied. The potential of Guayule is described in detail. Results of an investigation into the morphology of Guayule at the electron microscope level are given. Experiments, which would allow the biosynthesis of hydrocarbon in Guayule to be followed, were designed. In order to do this, knowledge of the biochemistry of rubber formation was used to select a tracer, mevalonic acid. Mevalonic acid is the precursor of all the terpenoids, a large class of hydrocarbons which includes rubber. It was found that when high enough concentrations of mevalonic acid are administered to seedling Guayule plants, build-ups of metabolized products are found within the chloroplasts of the seedlings. Also, tritium labeled mevalonic acid was used as a precursor, and its metabolic progress was followed by using the technique of electron microscope autoradiography. The results of these experiments also implicated chloroplasts of the Guayule plant in hydrocarbon production. The final task was the development …
Date: November 1, 1977
Creator: Bauer, T.E.
System: The UNT Digital Library
Stress induced reorientation of vanadium hydride (open access)

Stress induced reorientation of vanadium hydride

The critical stress for the reorientation of vanadium hydride was determined for the temperature range 180/sup 0/ to 280/sup 0/K using flat tensile samples containing 50 to 500 ppM hydrogen by weight. The critical stress was observed to vary from a half to a third of the macroscopic yield stress of pure vanadium over the temperature range. The vanadium hydride could not be stress induced to precipitate above its stress-free precipitation temperature by uniaxial tensile stresses or triaxial tensile stresses induced by a notch.
Date: October 1, 1977
Creator: Beardsley, M. B.
System: The UNT Digital Library
Electromigration of hydrogen and deuterium in vanadium, niobium, and tantalum (open access)

Electromigration of hydrogen and deuterium in vanadium, niobium, and tantalum

The electric mobility and effective valence of hydrogen and deuterium in vanadium, niobium, tantalum and three niobium-tantalum alloys were measured. A resistance technique was used to directly determine the electric mobility of hydrogen and deuterium at 30/sup 0/C while a steady-state method was used to measure the effective valence. The use of mass spectrographic techniques on a single specimen which contained both hydrogen and deuterium greatly increased the precision with which the isotope effect in the effective valence could be measured.
Date: October 1, 1977
Creator: Jensen, C. L.
System: The UNT Digital Library
Kinetic Studies of the Reactions Occurring Between Tungsten and Gases at Low Pressure and High Temperatures (open access)

Kinetic Studies of the Reactions Occurring Between Tungsten and Gases at Low Pressure and High Temperatures

Oxygen, nitrogen, and nitric oxide gases were passed through a system consisting of a tungsten filament, an ion gauge, and a mass spectrometer. The ion gauge recorded total pressures and the spectrometer recorded partlal pressures of O/sub 2/, N/sub 2/, NO, CO, COa, and H/sub 2/O. From the way these pressures changed with filamert temperature, the rates of conversion of O/sub 2/ to volatile tungsten oxides and O, and of NO to volatile tungsten oxides N/sub 2/ , O/sub 2/, and O were computed. The time rate of resistance change in the filament was used to compute the rate of conversion of tungsten to tungsten oxides. The filament temperatures ranged from 1950 through 2600 deg K and gas pressures ranged from 10/sup -8/ to 10/sup -6/ atm. For the tungsten-oxygen reaction, the rates of tungsten and oxygen loss were found to depend upon oxygen atom concentration on the surface. The rate of oxide power, depending upon the concentration of oxygen atoms on the surface. The reaction rate at constant oxygen pressure decreases with increasing temperature. For calculational purposes, the tungsten oxygen gas moleeules were assumed to be WO/sub 3/ only, though WO/sub 2/ and WO are other possible products. The …
Date: April 1, 1962
Creator: Anderson, H. U.
System: The UNT Digital Library
Use of a semiconductor laser in infrared spectroscopy (open access)

Use of a semiconductor laser in infrared spectroscopy

A semiconductor laser has certain properties which makes its use desirable as a continuous monitor of atmospheric pollutants. Its energy output is concentrated in widely separated energy modes of very narrow bandwidths (less than 10/sup -5/ cm/sup -1/) which can be centered on one infrared absorption line of one gas. This makes the laser quite selective. The energy in each mode is typically greater than 200 ..mu.. watts, and, because of the laser's small size, its light energy can be collimated over large distances with minimal optical losses and be easily detected. One can rapidly measure the decrease in transmission of the light due to the absorption of the light by the gas being monitored, and, using certain analytical parameters, which are different for each absorption line, one can determine the concentration of the gas in question immediately. In addition to the line center (nu/sub 0/), these analytical parameters are the intensity (S) and the half width at half maximum (..gamma..). The intensity (S) is dependent only on temperature when expressed in a per concentration basis and ..gamma.. is dependent on pressure. The Lorentzian lineshape equation K(nu) + S/..pi gamma..(((nu - nu/sub 0/)/..gamma..)/sup 2/ + 1)/sup -1/ is the equation …
Date: December 1, 1977
Creator: Morris, R. N.
System: The UNT Digital Library
Thermal Conductivity and Lorenz Function of Gadolinium, Terbium, and Holmium Single Crystals. (open access)

Thermal Conductivity and Lorenz Function of Gadolinium, Terbium, and Holmium Single Crystals.

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Date: January 1, 1968
Creator: Nellis, William Joel
System: The UNT Digital Library