Laminar flow in screwed pipe fittings

M.S.Charles W. Gorto

Influential Spheres: Examining Actors’ Perceptions of Education Governance

Many layers of education governance press upon U.S. schools, so we separated state actors into those internal to and those external to the system. In the process, we unpacked the traditional state–local dichotomy. Using interview data (n = 45) from six case-study states, we analyzed local leaders’, state-internal actors’, and state-external players’ perceptions of implementation flexibility and hindrances across several policy areas. We observed how interviewees’ spheres of influence linked to which policy areas they viewed as salient or not, and their relative emphaseson who and what within state education systems contributed to implementation flexibility and/or hindrances, and how these factors played out. We found important differences by sphere: the local sphere produced the most coherent findings, and state-internal was least coherent. We discuss implications for education governance research, applications for practitioners and policymakers, and a methodological contribution

A RENAISSANCE OF RADICAL FLUORINATION CHEMISTRY: METHODS, MECHANISMS, AND ADVANCES IN SELECTIVITY

As taught in most introductory organic chemistry courses, a safe, selective "radical fluorination" of sp3 C-H bonds has been virtually absent from the synthetic toolbox for decades. In 2012, such radical monofluorination tactics came to fruition employing metal initiators and mild sources of atomic fluorine. Specifically, our laboratory, contemporaneous with Groves' report on a manganese-porphyrin/silver(I) fluoride approach, introduced a copper(I)/Selectfluor protocol for aliphatic fluorination. Beyond these pioneering examples, a number of methods have been reported from our laboratory, and others, that accomplish similar chemistry using different transition metals, radical initiators, and both ultraviolet and visible light photosensitizers. Although these represent a substantial leap in controlling reactivity, the issue of selectivity remains an even greater challenge. The original work in this area proved fit for selective fluorination of highly symmetric molecules and those containing more activated benzylic C-H bonds; yet, so-called scattershot fluorination may occur on more complex molecules with multiple, dissimilar C-H bonds, thus generating a large number of products. Through better mechanistic understanding of the existing protocols, we have begun to envision ways to direct radical fluorination more reliably to enable practical late-stage fluorination of biologically relevant molecules. In addition to guiding sp3 C-H functionalization through the use of directing groups, we have also discovered ways to fluorinate carbon-centered radicals generated from strained and unstrained sp3 C-C bond cleavage that, in turn, also led to the unveiling of an unanticipated aminofluorination reaction. This dissertation discusses the serendipitous discovery of initial reactivity with the copper(I)/Selectfluor aliphatic fluorination method and the ongoing method development and mechanistic investigations that have paved the way for 1) alternative approaches to practical radical fluorination chemistry (with a more recent emphasis on photochemical approaches) and 2) timely improvements in selectivity. Among other applications, this work highlights methods that may be used for the selective fluorination of amino acids, peptides, steroids, terpenoids, and other natural products. We are optimistic that this rebirth of radical fluorination may find near-term adoption in a medicinal chemistry setting, where fluorine plays a prominent role

Cooler Target Development

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Feasibility Study of a Storage Cell Target

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Molecular Variation at a Candidate Gene Implicated in the Regulation of Fire Ant Social Behavior

The fire ant Solenopsis invicta and its close relatives display an important social polymorphism involving differences in colony queen number. Colonies are headed by either a single reproductive queen (monogyne form) or multiple queens (polygyne form). This variation in social organization is associated with variation at the gene Gp-9, with monogyne colonies harboring only B-like allelic variants and polygyne colonies always containing b-like variants as well. We describe naturally occurring variation at Gp-9 in fire ants based on 185 full-length sequences, 136 of which were obtained from S. invicta collected over much of its native range. While there is little overall differentiation between most of the numerous alleles observed, a surprising amount is found in the coding regions of the gene, with such substitutions usually causing amino acid replacements. This elevated coding-region variation may result from a lack of negative selection acting to constrain amino acid replacements over much of the protein, different mutation rates or biases in coding and non-coding sequences, negative selection acting with greater strength on non-coding than coding regions, and/or positive selection acting on the protein. Formal selection analyses provide evidence that the latter force played an important role in the basal b-like lineages coincident with the emergence of polygyny. While our data set reveals considerable paraphyly and polyphyly of S. invicta sequences with respect to those of other fire ant species, the b-like alleles of the socially polymorphic species are monophyletic. An expanded analysis of colonies containing alleles of this clade confirmed the invariant link between their presence and expression of polygyny. Finally, our discovery of several unique alleles bearing various combinations of b-like and B-like codons allows us to conclude that no single b-like residue is completely predictive of polygyne behavior and, thus, potentially causally involved in its expression. Rather, all three typical b-like residues appear to be necessary

Students' attitudes towards the introduction of a Personal and Professional Development portfolio: potential barriers and facilitators

Peer reviewedPublisher PD