A Study in Molecular Recognition: Synthesis of a Β-sheet Mimic & Quantitation of Metal Ions in Aqueous Solutions Through Solid Supported Semi-selective Chemosensors

From the hydrophobic effect, which is responsible for the organization of amphipathic molecules into cellular membranes, to the highly specific hydrogen binding patterns found in DNA base pairs that keeps our genetic material “zipped up”, non-covalent and reversible interactions are critical to properly functioning biological processes. Molecular recognition is an area of study that seeks to better understand these observed phenomena. In a general sense, association of “Host” and “Guest” molecules are based on ionic forces, hydrophobic interactions, cation-π effects, π-π stacking, conformational restriction, and many others. This dissertation will primarily focus on two projects that have an emphasis on studying molecular recognition. The first major project details the synthesis of a molecule that mimics the hydrogen bonding array of a β-sheet. β-sheets, secondary protein structures found ubiquitously in nature, are composed of peptide strands that associate through hydrogen bonds between an amide carbonyl on one strand to an amide -NH on an adjacent strand. As peptide strands begin to fold into a β-strand it pre-organizes the hydrogen bond donors and acceptors on the other edge allowing for the β-strand to propagate into a β-sheet. While this propagation is beneficial in the efficient folding of proteins, it makes it difficult for scientists to study this phenomenon in solution apart from the other complexities that exist in protein structures. Chemists have addressed this issue by creating synthetic mimics that simulate the hydrogen bonding array found in β-sheets along only one edge, greatly simplifying the observable phenomena and allowing them to study these effects in greater detail in solution. Based on the work of previous chemists I have developed a synthetic β-sheet mimic that can replace 3 amino acids in a peptide, has fluorescent properties, and can be incorporated by solid phase synthetic methods into peptides. Using a quinolone as a fluorescent core, I have synthesized a 3,6-diaminoquinol-4-one that has the same hydrogen bonding array. Preliminary studies appear to show association with itself in organic solvents. Additionally, I have developed synthetic schemes towards a pyrido[2,g]quinolone that would retain the same hydrogen binding array with a higher degree of conformational restriction and presumed fluorescent properties. This synthetic work will allow for future graduate students to study these hydrogen bonding interactions. The second major project in this dissertation details the work I have done on a hydrogel solid support. This work was done to enable the development of a real-time continuously monitoring sensor for the detection and quantitation of metal ions in aqueous solution. Specific azo dyes have long been known to show a shift in their absorbance spectrum with the addition of metal ions. When used as soluble molecules they are difficult to reuse due to their strong association to the metal ions. I have developed various hydrogel polymers with covalently attached azo dyes capable of metal ion diffusion in aqueous solutions. Optimization of these hydrogels has been achieved by variation of composition, crosslink-density, co-solvent selection and glass derivatization allowing for a robust attachment to a rigid backing. These hydrogels are optically transparent, allow for removal of the metals with acidic media, and demonstrate sufficient mechanical strength to allow them to be easily moved between analyte solutions. Two separate type of polymers have been developed to allow for either alkylation or acylation reactions to produce the covalent linkage of dye to hydrogel, each with its own advantages. With others in my research group and in collaboration with a local Milwaukee company, we have shown the azo-dyes covalently tethered to these hydrogels retain their optical properties and can be used for the identification and quantitation of aqueous metal species when incorporated into a flow cell. They are stable to hundreds of binding and release cycles and months of use, at least

Measuring Empathy, Feedback, Therapeutic Alliance, and Outcome with Sexual Offenders

Research has found the therapeutic alliance to be the strongest predictor of successful outcomes from treatment (Orlinsky, Ronnestad, & Willutzki, 2003) . While many populations have been studied to determine successful outcomes through the strengthening of the therapeutic alliance, psychological literature lacks research targeting the specific group of sexual offenders. The present research addressed this gap in psychological literature. Research focused upon three treatment groups involving 19 sexual offenders. The study investigated four hypotheses: (a) symptoms will be reduced as a result of treatment, (b) helping alliance will improve over time in treatment, (c) the strength of the helping alliance will be related to the degree of symptom improvement, (d) feedback given to the therapist about empathy (component of helping alliance) will foster better treatment outcomes. Preliminary outcome data was gathered using three different measures. The Helping Alliance Questionnaire II (HAQ II) is a widely used 19 item questionnaire that measures the strength of the client therapist alliance. The Empathy Scale Revised (ESR) is a 23-item test that asks patients to rate how caring, empathic, and genuine their therapists are. The Outcome Questionnaire 45.2 (OQ 45.2) is a 45-item test that measures distress symptoms. The pre-test included the HAQ-II, OQ-45.2, a demographic questionnaire, and an informed consent statement. The 2nd through the 11th week included only the ESR which was scored and interpreted by the lead researcher. The encoded results were then sent back to the lead therapist before the beginning of the next group session for the treatment group but not for control groups. The post-test included the OQ-45.2 and HAQ-II. Results indicate that during the course of treatment symptoms were reduced. Similarly, the helping alliance was improved. Finally, the strength of the alliance was related to the degree of improvement in symptoms. However, the feedback of ESR information did not affect outcomes. These results suggest that an effective working alliance can be formed with sex offenders. Second, the helping alliance is at least somewhat related to outcomes. Third, even for the relatively short treatment period investigated, symptomatic improvement can occur among sex offenders

Measuring Potential Dermal Transfer of a Pesticide to Children in a Child Care Center

Currently, the major determinants of children’s exposure to pesticides are not fully understood, and approaches for measuring and assessing dermal exposure in a residential setting have not been sufficiently evaluated. In one approach, dermal exposure is estimated using empirically derived transfer coefficients. To assess the feasibility of using this approach for assessing children’s exposure to pesticides, we conducted a study was conducted in a child care center that had a preexisting contract with a pest control service for regular monthly pesticide applications. Children in the selected child care center were monitored using full-body cotton garments to measure dermal loading. Pesticide residues on classroom surfaces were measured in the areas where the children spent time. Measured surface-wipe loadings ranged from 0.47 to 120 ng/cm(2), and total garment loadings ranged from 0.5 to 660 pg/cm(2). The garment and surface loading measurements were used to calculate dermal-transfer coefficients for use in assessing children’s residential exposure to pesticides. Dermal-transfer coefficients calculated using these data range from approximately 10 to 6,000 cm(2)/hr. The wide range in these values demonstrates the importance of developing standard surface-measurement protocols if this approach is to be used to assess dermal exposure in a residential environment. The upper-range values resulting from this study were found to be similar to the default value used by the U.S. Environmental Protection Agency to assess children’s dermal exposures resulting from contact with indoor surfaces

Preparation of ultralow-friction surface films on vanadium diboride.

In this paper, we present a simple annealing procedure (which we refer to as ''flash-annealing'' because of short duration) that results in the formation of an ultralow friction surface film on vanadium diboride (VB{sub 2}) surfaces. This annealing is done in a box furnace at 800 C for a period of 5 min. During annealing, the exposed surface of the VB{sub 2} undergoes oxidation and forms a layer of boron oxide (B{sub 2}O{sub 3}). In open air, the B{sub 2}O{sub 3} layer reacts spontaneously with moisture and forms a boric acid (H{sub 3}BO{sub 3}) film. The friction coefficient of a 440C steel pin against this H{sub 3}BO{sub 3} film is {approx}0.05, compared to 0.8 against the as-received VB{sub 2}. Based on Raman spectroscopy and electron microscopy studies, we elucidate the ultralow friction mechanism of the flash-annealed VB{sub 2} surfaces