Touching Water: Exploring Thermodynamic Properties with Clausius App

The effect of pressure and temperature on the properties of water is a critical concept within engineering curriculum. Instructors spend considerable effort training students to use reference databases; traditionally in tabulated forms or more recently with use of computer-aided references. The reliance on tables however, places undue emphasis on the property values over property relationships. Understanding thermodynamic relationships and the trends are of greater value from a student learning perspective than the numeric value of the properties. This value is highlighted by the practice of asking students to sketch thermodynamic cycles on a temperature-entropy T-s or pressure-volume P-v chart. The typical analytical steps involving property retrieval followed by depiction on a property chart is disjointed and reversed. If property values are acquired directly from a T-s or P-v property chart, the process is integrated into a single intuitive step that promotes deeper understanding. While printed charts exist, they can be challenging to read considering a single point must supply up to six discrete values (namely P, T, v, u, h, and s). Instead, an interactive property chart that displays properties values for states identified by the user can be highly effective. This was the inspiration behind the Clausius app. Clausius allows users to simply tap on a desired state within a T-s chart to retrieve property values. The design was driven by the need to visualize thermodynamic property relationships as opposed to simply delivering property values. The app was subsequently studied in thermodynamics courses for its impact on student learning (with a treatment group) when compared to accessing properties via steam tables (with a control group). The intervention involved a guided exploration of water properties by the participants, followed by an assessment of students’ understanding of the property trends. Three sets of treatment and control groups participated, across two campuses and three departments. The outcomes provide a strong endorsement for Clausius and its ability to teach property trends. Student feedback also supported the advantages of more visual and dynamic reference for water properties. Overall, enabling students to ‘touch and explore’ thermodynamic properties seems more intuitive and conducive to deeper learning than the traditional use of tabulated property values

Oxidation of substrates tethered to N-donor ligands for modeling non-heme diiron enzyme active sites

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.Vita.Includes bibliographical references.Chapter 1. Modeling Carboxylate-Rich Diiron Sites of Dioxygen-Dependent Non-Heme Enzymes Carboxylate-bridged diiron centers are employed in a variety of biological systems to activate dioxygen for substrate oxidation, and small molecule models have been synthesized to mimic this chemistry outside of the natural systems. In this introductory chapter a brief overview of terphenyl-based carboxylate systems is given and progress toward achieving structural, spectroscopic, and functional models of the protein active sites is reviewed. Chapter 2. Synthesis and Reactivity of Carboxylate-Bridged Diiron(II) Complexes with Primary Alkyl Amine Ligands The synthesis and crystallographic characterization of a series of diiron(II) complexes with sterically hindered terphenyl carboxylate ligands and alkyl amine donors are presented. The compounds ... , where ... 2,6-di(p-tolyl)benzoate, and [...] (L= NH₂(CH₂)₃SMe (4); NH₂(CH₂)₃CCH (5)), where ... is 2,6-di(3,5- dimethylphenyl)benzoate, were prepared as small molecule mimics of the catalytic sites of carboxylate-bridged non-heme diiron enzymes.(cont.) The compounds with the ... carboxylate form tetrabridged structures, but those containing the more sterically demanding ... ligand have only two bridging ligands. The ancillary nitrogen ligands in these carboxylate-rich complexes incorporate potential substrates for the reactive metal centers. Their oxygenation chemistry was studied by product analysis of the organic fragments following decomposition. Compound 1 reacts with dioxygen to afford PhCHO in [approx.] 30% yield, attributed to oxidative dealkylation of the pendant benzyl group. Compound 3 decomposes by established bimolecular pathways upon exposure to dioxygen at low temperatures. When the ... carboxylate is replaced by the ... ligand, as in 5, this behavior no longer occurs. Instead the six- coordinate iron(III) complex with one bidentate and two monodentate carboxylate ligands, [...] (6), was isolated from the reaction mixture following the oxidation of 5.(cont.) Chapter 3. C-H Activation with Benzyl- and Ethyl- Substituted Pyridine Ligands in Carboxylate-Bridged Diiron(II) Complexes with Dioxygen In this study benzyl and ethyl groups were appended to pyridine and aniline ancillary ligands in diiron(II) complexes of the type [...], where ... is the sterically hindered 2,6-di(p-tolyl)- or 2,6-di(p-fluorophenyl)benzoate (R = Tol or 4-FPh, respectively). These crystallographically characterized compounds were prepared as models for the diiron(II) center in the hydroxylase component of soluble methane monooxygenase (MMOH). Use of 2- benzylpyridine (2-Bnpy) afforded doubly-bridged [...] (1) and [...] (4), whereas tetra-bridged [...] (3) resulted when 4-benzylpyridine (4-Bnpy) was employed. Similarly, 2-(4-chloro- benzyl)pyridine (2-(4-ClBn)py) and 2-benzylaniline (2-Bnan) were employed as N-donor ligands to prepare [...] (2) and [...](5). Placement of the substituent on the pyridine ring had no effect on the geometry of the diiron(II) compounds isolated when 2-, 3-, or 4-ethylpyridine (2-, 3-, or 4-Etpy) was introduced as the ancillary nitrogen ligand. The isolated [...] (6), [...] (7), [...] (8), and [...] (9) complexes all contain doubly-bridged metal centers.(cont.) The oxygenation of compounds 1 - 9 was studied by product analysis of the organic fragments following decomposition. Hydrocarbon fragment oxidation occurred for compounds in which the substrate moiety is in close proximity to the diiron center. The extent of oxidation depended on the exact makeup of the ligand set. Chapter 4. A Thermally Sensitive Intermediate Generated in the Reaction of [...] with Dioxygen In this chapter the reaction of [...] (la) with dioxygen at low temperature to form the 02-sensitive intermediate (lb) was investigated. Various spectroscopic methods including UV-visible, resonance Raman (rR), electron paramagnetic resonance (EPR), and M6ssbauer were applied to study the mechanism and the intermediates involved. Chapter 5. Synthesis and Reactivity Studies of Carboxylate-Bridged Diiron(II) Compounds with Dangling Sulfur-Containing Substrates Functional models of the carboxylate-bridged diiron active site in soluble methane monooxygenase are described in which potential substrates are introduced as substituents on bound pyridine ligands.(cont.) Thiol, sulfide, and sulfoxide moieties tethered to pyridine were allowed to react with the prefabricated diiron(II) complex [...], where ... is a sterically hindered 2,6-di(p-tolyl)benzoate. The resulting diiron(II) complexes were characterized crystallographically. Triply- and doubly-bridged compounds [...] (1), [...] (2), and [...] (3) resulted when 2-phenylthiopyridine (2-PhSpy), 2-methylthio- pyridine (2-MeSpy) and 2-pyridylmethylsulfoxide (2-MeS(O)py), respectively, were employed. Use of 2-mercaptopyridine (2-HSpy) afforded the mononuclear complex [...] (4a). The dioxygen reactivity of these iron(II) complexes was investigated. A dioxygen-dependent intermediate (4b) formed upon exposure of 4a to 0₂, the electronic structure of which was probed by various spectroscopic methods. Exposure of 1 - 3 to dioxygen revealed both sulfide and sulfoxide oxidation. Chapter 6. Effect of Substrate Position in Diphenylphosphinopyridine Ligands on Geometry and Reactivity of Diiron(II) Carboxylate-Bridged Compounds In this chapter the exploration of carboxylate-bridged diiron(II) compounds containing phosphino-derivatized pyridine ligands to mimic aspects of chemistry at the active site of soluble methane monooxygenase (sMMO) is presented.(cont.) 2-, 3-, or 4-Diphenylphosphino moieties incorporated into a pyridine ligand (2-, 3-, or 4-Ph₂Ppy) were allowed to react with the preassembled diiron(II) complex [...], where ... is a sterically hindered 2,6-di(p-tolyl)- or 2,6-di(p-fluorophenyl)benzoate (R = Tol or 4-FPh). Triply-, doubly-, and tetrabridged compounds [...] (1), [...] (2), [...] (3), [...] (4) resulted and were characterized crystallographically. Exposure of 1 - 4 to dioxygen revealed both stoichiometric and catalytic phosphine oxidation. Oxidation of 4 in CH₂C1₂ affords [...] (6), which contains the biologically relevant [Fe₂([mu]-OH)₂([mu]-O₂CR)] ³⁺ core. This reaction is sensitive to the choice of carboxylate ligands, however, since the p-tolyl analog 1 yielded a hexanuclear species, 5, upon oxidation.by Emily Carrig Carson.Ph.D

Upconversion processes in Yb-sensitized Tm:ZBLAN

A spectroscopic study of 22 rare-earth-ion doped ZBLAN (fluorozirconate) glass was done to study feasibility of sensitizing Tm:ZBLAN with Yb to facilitate development of an efficient, conveniently pumped blue upconversion fiber laser. it was found that, under single-color pumping, 480 nm emission from Tm{sup 3+} was strongest when Yb,Tm:ZBLAN is excited at 975 nm; the strongest blue blue emission was obtained from a glass sample with 2.0 wt% Yb + 0.3 wt% Tm. Also, for weak 975 nm pump intensities, strength of blue upconversion emission can be greatly enhanced by simultaneously pumping at 785 nm. This increased upconversion efficiency is due to reduced number of energy transfer steps needed to populate the Tm{sup 3+} {sup 1}G{sub 4} energy level. Measurements of fluorescence lifetimes vs dopant concentration were also made for Yb{sup 3+}, Tm{sup 3+}, and Pr{sup 3+} transitions in ZBLAN in order to better characterize concentration quenching effects. Energy transfer between Tm{sup 3+} and Pr{sup 3+} in ZBLAN is also described

Radical HRM innovation and competitive advantage: The Moneyball story

Moneyball (Lewis, 2003), a New York Times bestseller, is a book about baseball. When read through a broader lens, however, Moneyball is also a book about innovation, resistance to change, competitive advantage, achieving excellence, and, of most relevance here, human resource management. While many would agree that the radical innovation described in Moneyball represents a “new vision of management” in baseball, this article describes how Moneyball lessons might contribute to a “new vision of HRM” in various types of organizations. The focus of the article is on what HR executives and scholars can learn from the Moneyball phenomenon. More specifically, the authors address a number questions related to the Moneyball story that have relevance to successfully implementing HRM innovations; these questions have to do with overcoming resistance to the implementation of radical innovation and how HRM innovation can contribute to sustainable competitive advantage. © 2006 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/49274/1/20100_ftp.pd

Special and inclusive education in the Republic of Ireland: reviewing the literature from 2000 to 2009

Provision for pupils with special educational needs in Ireland has undergone considerable change and review in the first decade of the twenty first century. In response to international demands for a more equitable education system which recognises diversity and considers how schools might address the needs of pupils who have been previously marginalised, Irish legislation has focused upon the development of inclusive schooling. Researchers during this period have endeavoured to understand how responses to the demand for greater inclusion have impacted upon the perceived need for change. This paper reviews the research literature for this period and identifies four key themes under which research has been conducted. The literature pertaining to these themes is explored and a possible agenda for future researchers identifie