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Investigation of Ultratrace Metallic and Organic Contaminants in Semiconductor Processing Environments

Investigation of Ultratrace Metallic and Organic Contaminants in Semiconductor Processing Environments

Date: May 1997
Creator: Xu, Fei, 1971-
Description: Detection of ultratrace levels of metallic ion impurities in hydrofluoric acid solutions and alkaline hydrogen peroxide solution was demonstrated using a silicon-based sensing electrode. The sensor's operation principle is based on direct measurements of the silicon open-circuit potential shift generated by the interaction between metallic ions and the silicon-based sensing surface. The new sensor can have practical applications in the on-line monitoring of microelectronic chemical processing. The detection of Ag+ content in KODAK waste water was carried out successfully by this novel sensor. Trace levels of organic impurities in the hydrofluoric acid solutions and in the cleanroom air were characterized by multiple internal reflection infrared spectroscopy (MIRIS) using an organics probe prepared directly from a regular silicon wafer.
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An Investigation of Young Children's Awareness of Line and Line Quality in Art and Graphic Reproductions

An Investigation of Young Children's Awareness of Line and Line Quality in Art and Graphic Reproductions

Date: December 1994
Creator: Young, Jeffry R. (Jeffry Ray)
Description: The purpose of this study was to determine whether kindergarten children possess the ability to recognize, match, and discuss lines and line qualities. Using graphics and art reproductions, three matching tasks were constructed which examined young children's awareness of the line qualities of length, width, straightness, direction, movement, and uniformity. Graphics and art reproductions were also used to construct two tracing tasks employed to examine young children's awareness of actual and implied lines. The tasks were administered to 69 kindergarten students from four elementary schools in a public school district in the north central Texas area.
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An Investigation to Determine Improvement in the Social Status of Children Through Concetrated Effort

An Investigation to Determine Improvement in the Social Status of Children Through Concetrated Effort

Date: 1950
Creator: Atkins, Thelma
Description: The problem of this study is an investigation of the development of social adjustment in thirty-three first-grade pupils in Gainesville, Texas, during 1949-1950. The purpose of the study is to determine each child's total readiness status at the beginning of the investigation, surround each with socializing experiences appropriate to his need, and then determine whether measurable benefits appear to result from his participation in the specific activities designed for social development.
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Investigations of neuronal network responses to electrical stimulation in murine spinal cultures.

Investigations of neuronal network responses to electrical stimulation in murine spinal cultures.

Date: December 2001
Creator: Sparks, Christopher A.
Description: Spontaneous activity in neuronal networks in vitro is common and has been well documented. However, alteration of spontaneous activity in such networks via conditioning electrical stimulation has received much less experimental attention. Two different patterns of electrical stimulation were used to enhance or depress the level of spontaneous activity in spinal cord cultures. High-frequency stimulation (HFS), a method routinely shown to increase the efficacy of synaptic transmission, was employed to augment spontaneous activity. Low-frequency stimulation (LFS), the technique often applied to depress synaptic efficacy, was employed to decrease spontaneous activity. In addition, LFS was used to reverse the effect of HFS on spontaneous activity. Likewise, HFS was applied to counter the effect of LFS. Because these networks were grown on multi-microelectrode plates (MMEPs), this allowed the simultaneous stimulation of any combination of the 64 electrodes in the array. Thus, the possible differences in response to single versus multi-electrode stimulation were also addressed. Finally, test-pulses were delivered before and after the conditioning stimulation on the same stimulation electrode(s) in order to assess the change in mean evoked action potentials (MEAPs). Dissociated spinal tissue from embryonic mice was allowed to mature into self-organized networks that exhibited spontaneous bursting activity after two weeks ...
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Investigations of Thermochemistry and the Kinetics of H Atom Radical Reactions

Investigations of Thermochemistry and the Kinetics of H Atom Radical Reactions

Access: Use of this item is restricted to the UNT Community.
Date: December 2002
Creator: Peebles, Lynda Renee
Description: The thermochemistry of several species, and the kinetics of various H atom radical reactions relevant to atmospheric and combustion chemistry were investigated using ab initio theoretical techniques and the flash photolysis / resonance fluorescence technique. Using ab initio quantum mechanical calculations up to the G3 level of theory, the C-H bond strengths of several alkanes were calculated. The bond strengths were calculated using two working reactions. From the results, it is apparent that the bond strengths decrease as methyl groups are added to the central carbon. The results are in good agreement with recent experimental halogenation kinetic studies. Hydrogen bond strengths with sulfur and oxygen were studied via CCSD(T) theory, together with extrapolation to the complete basis set limit. The results for the bond dissociation energies (ground state at 0 K, units: kJ mol-1) are: S-H = 349.9, S-D = 354.7, HS-H = 376.2, DS-D = 383.4, and HO-H = 492.6. These data compare well with experimental literature. The rate constants for the isotopic reactions of H + H2S, D + H2S, H + D2S, and D + D2S are studied at the QCISD(T)/6-311+G(3df,2p) level of theory. The contributions of the exchange reaction versus abstraction are examined through transition state ...
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Investing and Hedging Techniques in the Convertible Bond Market

Investing and Hedging Techniques in the Convertible Bond Market

Date: June 1969
Creator: Vinson, Charles E. (Charles Eldred)
Description: This study was designed to yield three types of information: (1) The degree of perfection prevailing in the parimary and secondary convertible bond markets; (2) the profit potential of various investing and hedging techniques in the convertible bond market; and (3) a judgment on whether each technique can be classified as rational or irrational.
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Investment decisions: Influence of an Internet stock message board.

Investment decisions: Influence of an Internet stock message board.

Date: December 2007
Creator: Pleis, Letitia Meier
Description: The Internet provides many sources of financial information that investors can use to help with investment decisions and in interpreting companies' accounting information. One source of information is Internet stock message boards such as those at Yahoo! Finance. This source allows for anonymous postings and information exchange. Despite the possibility of the information being incorrect many individuals visit these message boards. The purpose of this study is to investigate Internet stock message boards and address the primary question: From an individual investor perspective, do message boards, which contain accounting information, influence investment decisions? The question is addressed using psychology rumor literature and attitude theories. Message board postings are a type of rumor, since not all the information is verified and is usually intended to persuade a belief or influence a decision. Further, the messages may influence an investor by causing a change in attitude about the investment. Using an experiment, message board influence on an investment decision and attitude was tested. The results indicated that individuals that received negative message board postings did have a significantly higher change in investment amount as compared to a control group that did not receive any message postings. The positive message board group and ...
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The Invisible Dragon

The Invisible Dragon

Date: December 2012
Creator: Boutwell, Nathan
Description: This collection of memoir essays chronicles the author's 19 year struggle with chronic depression. "The Invisible Dragon" explores the onset of the disease and its cure. "The Silent Typewriter" looks at how it affected the author as a writer. "Roses for Trish" discusses how it affected his wife. "My Mother's Son" explores the possibility that he inherited depression from his mother. The final essay, "The Dragon Returns" probes the author's life in 2012 with the probability that he has a personality disorder. The preface examines several depression memoirs and explores the strategies used by William Styron, Elizabeth Wurtzel and Kay Redfield Jamison to prevent sliding into the pitfalls inherent in a linear structure. Among these are the use of alternative structures, language, characterization, focus and imagery.
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Involvement in Admission to Two Homes for the Aged

Involvement in Admission to Two Homes for the Aged

Date: August 1963
Creator: Howze, Glenn Ray
Description: The study reported in the thesis attempted to examine the decision-making process for the institutionalization of older people in homes for the aged. More specifically, it sought to determine who was responsible for the decisions, to discover if this responsibility was related to selected social factors, and to ascertain if it affected the adjustment of older people to the institutional setting.
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Ion Beam Synthesis of Carbon Assisted Nanosystems in Silicon Based Substrates

Ion Beam Synthesis of Carbon Assisted Nanosystems in Silicon Based Substrates

Date: May 2011
Creator: Poudel, Prakash Raj
Description: The systematic study of the formation of β-SiC formed by low energy carbon ion (C-)implantation into Si followed by high temperature annealing is presented. The research is performed to explore the optimal annealing conditions. The formation of crystalline β-SiC is clearly observed in the sample annealed at 1100 °C for a period of 1 hr. Quantitative analysis is performed in the formation of β-SiC by the process of implantation of different carbon ion fluences of 1×1017, 2×1017, 5×1017, and 8×1017 atoms /cm2 at an ion energy of 65 keV into Si. It is observed that the average size of β-SiC crystals decreased and the amount of β-SiC crystals increased with the increase in the implanted fluences when the samples were annealed at 1100°C for 1 hr. However, it is observed that the amount of β-SiC linearly increased with the implanted fluences up to 5×1017 atoms /cm2. Above this fluence the amount of β-SiC appears to saturate. The stability of graphitic C-C bonds at 1100°C limits the growth of SiC precipitates in the sample implanted at a fluence of 8×1017 atoms /cm2 which results in the saturation behavior of SiC formation in the present study. Secondly, the carbon cluster formation process ...
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