MODELING THE CONDENSED-PHASE BEHAVIOR OF Π-CONJUGATED POLYMERS

It is well established that the morphology and physical properties of an organic semiconducting (OSC) material regulate its electronic properties. However, structure-function relationships remain difficult to describe in polymer-based OSC, which are of particular interest due to their robust mechanical properties. If relationships among the molecular and bulk levels of structure can be found, they can aid in the design of improved materials. To explore and detail important structure-function relationships in polymer-based OSC, this work employs molecular dynamics (MD) simulations to study various π-conjugated polymers in different environments. Two independent investigations are discussed in this work. One investigation examines how the purposeful disruption of the π-conjugated backbone to increase the chain flexibility impacts the chain structure and packing in the condensed phase. This is done by adding a conjugation break spacer (CBS) unit of one to ten carbons in length into the monomer structure of diketopyrrolopyrrole-based polymers. It is found that trends in the folding and glass structure follow the increase and the parity (odd versus even) of the CBS length. The second investigation analyzes a variety of polymers and small molecule acceptor (SMA) blends to observe the effects of changing the shape of either component and the physical properties of the material, as well as the structure of the polymer chains. It is found that the conjugated core, the side chains, and the planarity or sphericity each influence the density and diffusion of the materials made

Immunoreactivity of anti pZP antibodies from the serum of SpayVac vaccinated mares to equine zona protein

2014 Summer.Includes bibliographical references.Immunocontraception with the porcine zona pellucida (pZP) antigen is a well-published means of wild horse contraception. There are three pZP vaccines currently proposed for use in horses, Zonastat-H®, PZP-22, and SpayVac®. Despite abundant research concerning the safety and contraceptive efficacy of pZP vaccines in numerous species, the contraceptive mechanisms of the pZP antigen remain unclear and have not been investigated thoroughly for SpayVac. We investigated the immunoreactivity of anti pZP antibodies from the serum of SpayVac vaccinated mares to equine zona protein using Western blot and immunohistochemical techniques. These techniques were first applied using a bovine model because bovine oocytes are more easily obtained in large quantities relative to equine oocytes. Once the procedure was validated, equine samples were utilized. Western blot analysis revealed immunoreactivity of anti pZP antibodies that were produced in response to SpayVac vaccination to protein isolated from mature equine oocytes, equine zona pellucidae, equine follicular tissue, and equine ovarian stromal tissue. Immunohistochemical analysis identified the location of binding of anti pZP antibodies to the zona pellucida of mature oocytes isolated from Graafian follicles as well as the zona pellucida of immature oocytes in ovarian tissue. Western blot and immunohistochemical analyses also indicate high specificity of anti pZP antibodies for equine zona protein and predominant affinity for zona protein 3. Collectively, results suggest a model where anti pZP antibodies produced in response to SpayVac vaccination are immunoreactive to equine zona protein in vitro. If available in the follicular fluid and able to permeate the ovary following SpayVac vaccination, anti pZP antibodies may act on not only mature oocytes, but also oocytes of growing follicles in vivo. The results of this study lend insight into the infertility observed following SpayVac vaccination, and may also help explain the long-term ovarian effects following pZP vaccination reported by other studies

DEVELOPING PEDAGOGICAL CONTENT KNOWLEDGE AS COMMUNAL PRACTICE: A CASE STUDY OF CHEMISTRY GRADUATE TEACHING ASSISTANTS

Learning does not only happen during dedicated instructional time, which also applies to learning how to teach. Teachers can reflect on their practice while working to continue to improve and develop their teaching skills. In addition to self-reflection, teachers can also learn from their colleagues to experiment with new practices and take others’ teaching knowledge into their repertoire. Understanding how these two processes function can lead to developments in teacher education and professional development, specifically for initiatives that seek to promote collaboration among teachers. Post-secondary educators in particular can benefit from collaborative and reflective practices to improve their teaching, especially given that these educators do not often have rigorous teaching training. To explore how teaching practices can be influenced by interactions with one’s community of educator colleagues, this work combines the recently developed refined consensus model of pedagogical content knowledge (PCK) with Wenger’s communities of practice framework to explore how teaching knowledge moves throughout a community of educators. Taking an ethnographic approach that involves participant observation and in-depth immersion, a cohort of graduate teaching assistants (GTAs) in a chemistry department is studied to learn how teaching knowledge and practice are developed through experience in their cohorts of fellow GTAs. Specifically, this work compares the experiences of recitation and laboratory GTAs teaching in the same discipline and level of course: general chemistry. Observations of GTA training, weekly meetings, and instructional time are supplemented with data from semi-structured and informal interviews to determine specific features of this group’s PCK and the social factors that moderate its uptake by members of the group. Analyzing the knowledge bases that contribute to PCK reveals that the structure of the specific job these GTAs perform mitigates the development of their teaching practices, specifically their content knowledge, which is a prerequisite for developing PCK and therefore limits its growth. Possibilities for connecting this research into practice are explored, as is the benefit of the new framework that this study seeks to validate

Effects of mask fitness and worker education on the prevention of occupational dust exposure

To decrease the incidence of pneumoconiosis, we examined dust protective mask performance and its relation to pulmonary function as well as the effects of worker education on the proper wearing of masks. One hundred and seventy-eight workers from 15 factories subject to dust exposure participated in this study. All participants were interviewed to obtain relevant personal information and underwent both a mask leakage and a pulmonary function test. The mask leakage was expressed as a percentage, with under 10% leakage indicating that the dust protective mask worked efficiently. In addition, 23 workers from 2 factories were educated on how to wear masks properly. The average mask leakage was 24.3%, and 58% of workers wore ineffective masks. Though pulmonary function was almost normal, the percent vital capacity (%VC) tended to be lower depending on the mask leakage. Mask education, which was very easy and took only a short time, dramatically decreased average mask leakage from 32.1% to 10.5% (p0.001). Educating workers to wear masks properly might prevent the worsening of pulmonary function in response to dust exposure. Appropriate mask fitness by education could be useful in preventing the development of pneumoconiosis.</p

Method to make a single-step etch mask for 3D monolithic nanostructures

Current nanostructure fabrication by etching is usually limited to planar structures as they are defined by a planar mask. The realisation of three-dimensional (3D) nanostructures by etching requires technologies beyond planar masks. We present a method to fabricate a 3D mask that allows to etch three-dimensional monolithic nanostructures by using only CMOS-compatible processes. The mask is written in a hard-mask layer that is deposited on two adjacent inclined surfaces of a Si wafer. By projecting in single step two different 2D patterns within one 3D mask on the two inclined surfaces, the mutual alignment between the patterns is ensured. Thereby after the mask pattern is defined, the etching of deep pores in two oblique directions yields a three-dimensional structure in Si. As a proof of concept we demonstrate 3D mask fabrication for three-dimensional diamond-like photonic band gap crystals in silicon. The fabricated crystals reveal a broad stop gap in optical reflectivity measurements. We propose how 3D nanostructures with five different Bravais lattices can be realised, namely cubic, tetragonal, orthorhombic, monoclinic, and hexagonal, and demonstrate a mask for a 3D hexagonal crystal. We also demonstrate the mask for a diamond-structure crystal with a 3D array of cavities. In general, the 2D patterns for the different surfaces can be completely independent and still be in perfect mutual alignment. Indeed, we observe an alignment accuracy of better than 3.0 nm between the 2D mask patterns on the inclined surfaces, which permits one to etch well-defined monolithic 3D nanostructures.Comment: 18 pages, 10 figure

Method for growing low defect, high purity crystalline layers utilizing lateral overgrowth of a patterned mask

A method for growing a high purity, low defect layer of semiconductor is described. This method involves depositing a patterned mask of a material impervious to impurities of the semiconductor on a surface of a blank. When a layer of semiconductor is grown on the mask, the semiconductor will first grow from the surface portions exposed by the openings in the mask and will bridge the connecting portions of the mask to form a continuous layer having improved purity, since only the portions overlying the openings are exposed to defects and impurities. The process can be iterated and the mask translated to further improve the quality of grown layers