1,786 research outputs found

    New Metal-NHC Complexes: Synthesis, Characterization, and Uses

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    N-Heterocyclic Carbenes (NHC) present a viable alternative to traditional phosphine ligands in a variety of organometallic mediated catalytic reactions. Singlet ground-state carbenes are stabilized by the push-pull presence of two adjacent nitrogen atoms in an imidizolium 5-membered ring, allowing neutral electron donor properties. The ability to synthesize a variety of NHC ligands with differing steric and electronic properties is possible by changing the sustiuents on the nitrogen atoms of the imidizolium. Tunable characteristics and enhanced chemical and thermal stability give NHC’s an advantage over phosphines in many catalytic systems. This dissertation focuses on the use N-Hetercyclic Carbenes in a variety of organometallic complexes. The synthesis of NHC complexes with a variety of transition metals is described. The transition metals complexed with NHC’s include palladium, iridium, nickel and ruthenium. The catalytic activity of the metal-NHC complexes is investigated as well

    The ATIS Message: A Study in One-Way Communication

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    The purpose of this study was to explore the effects of high fidelity digital voice transmission, some aspects of information processing and the effect of short-term memory and long-term memory on one-way verbal communication. The experiment consisted of one realistic scenario with each of the twenty-four subjects involved recording on paper each of the sixteen Automatic Terminal Information Serice (ATIS) messages that they heard. Each subject heard each message one time, and the listening devices used were changed after four messages. The ATIS message consists of eleven hem groups of information. The results were viewed in group, number, and word errors. The largest error was the error of omission, and the most errors were found in message item 11 of the remarks section. The lengthy and complex remarks section overtaxed the capacity of the short term memory and resulted in large numbers of omission errors

    New Metal-NHC Complexes: Synthesis, Characterization, and Uses

    Get PDF
    N-Heterocyclic Carbenes (NHC) present a viable alternative to traditional phosphine ligands in a variety of organometallic mediated catalytic reactions. Singlet ground-state carbenes are stabilized by the push-pull presence of two adjacent nitrogen atoms in an imidizolium 5-membered ring, allowing neutral electron donor properties. The ability to synthesize a variety of NHC ligands with differing steric and electronic properties is possible by changing the sustiuents on the nitrogen atoms of the imidizolium. Tunable characteristics and enhanced chemical and thermal stability give NHC’s an advantage over phosphines in many catalytic systems. This dissertation focuses on the use N-Hetercyclic Carbenes in a variety of organometallic complexes. The synthesis of NHC complexes with a variety of transition metals is described. The transition metals complexed with NHC’s include palladium, iridium, nickel and ruthenium. The catalytic activity of the metal-NHC complexes is investigated as well

    Fractal Like Snowflakes Generated by Non-Contractive Function Systems

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    At the heart of this thesis is the examination of a non-contractive iterative function system T on the Hausdorff metric space of all compact subset of ℝ . Despite the absence of an 2 attracting fixed point, an examination reveals the appearance of fractal-like shapes (snowflakes) when applying the Barnsley’ random walk method to study the iterative sequence n(0) ( ∈ ℕ) for = 1 ∪ 2 ∪ 3, where 1() = , 2() = + , and 3() = - , and = π/3

    Brain Amino Acids and Biogenic Amines Under Various Atmospheric Mixtures Semiannual Report, 1 Mar. 1965 - 30 Apr. 1966

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    Effects of exposure to different gaseous atmospheric mixtures on free amino acids and biogenic amines in rat brain

    The Productivity Consequences of Two Ergonomic Interventions

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    Pre- and post-intervention data on health outcomes, absenteeism, and productivity from a longitudinal, quasi-experimental design field study of office workers was used to evaluate the economic consequences of two ergonomic interventions. Researchers assigned individuals in the study to three groups: a group that received an ergonomically designed chair and office ergonomics training; a group that received office ergonomics training only; and a control group. The results show that while training alone has neither a statistically significant effect on health nor productivity, the chair-with-training intervention substantially reduced pain and improved productivity. Neither intervention affected sick leave hours.ergonomics, chair, pain, DeRango, Upjohn

    SOUTHERN AGRICULTURE UNDER THE 2002 FARM BILL: A REPRESENTATIVE FARMS APPROACH

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    The 2002 Farm Bill affects economic activity of farms and ranches in the southern United States. Using stochastic simulation techniques, key financial variables were projected for 39 representative farms and ranches in ten southern states. Results indicate 24 of 39 farms studied have more than a 40 percent likelihood of having annual cash flow deficits during the period 2002 through 2007. Results are largely consistent across commodities and between moderate and large size farms in the same geographic area.Agricultural and Food Policy,
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