As new adhesive products become available in restorative dentistry, investigating their potential application for orthodontic use is warranted. Vertise Flow (Kerr) is a self-adhering flowable resin and is being marketed for use as a sealant, porcelain repair and small class I restorations. It has potential for use as an orthodontic adhesive. Objective: Determine if Vertise Flow (Kerr) is suitable for bonding fixed orthodontic appliances to enamel, restorative resin composite and porcelain with minimal surface preparation. Methods: Shear Bond Strengths (SBS) from six (6) groups of fifteen (15) bonded stainless steel lingual buttons (Ormco) were obtained over three time points (24hr, 7 days, and 3 months). The six test groups were: 1.Vertise Flow to enamel (Tt) with coarse pumice debridement, 2. Transbond XT (3M, Unitek) to enamel (Tc) with phosphoric acid etching [control], 3.Vertise Flow to Herculite Ultra (Kerr) (Cc) with coarse pumice debridement, 4. Vertise Flow to Filtek Supreme Ultra (3M, ESPE) (Ct) with coarse pumice debridement, 5. Vertise Flow (Kerr) to porcelain (Pt) with diamond bur roughening, and 6. Transbond XT (3M Unitek) to porcelain (Pc) with hydrofluoric acid etching. Samples were stored in distilled water and incubated at 37C. The buttons were then debonded with a Zwick Universal Testing machine using a 10 kN load cell with a crosshead speed of 0.5mm/min. Debonded buttons were evaluated based on a modified Adhesive Remnant Index (ARI). Statistical assessment of the data was performed using parametric and non-parametric tests, with p<0.05 as the threshold for statistical significance. Results: The mean SBS obtained in all groups at each time point were >4MPa and varied between 8.69MPa and 27.44MPa. Statistical differences were found within the composite and porcelain groups at T1, and the enamel and composite groups at both T2 and T3. Nearly half of the sample (47.2%) achieved an ARI score of 5 (100% adhesive left on button base). Conclusion: Vertise Flow potentially provides clinically acceptable bond strengths to enamel, restorative resin composite and porcelain with minimal surface preparation. Furthermore, upon removal, minimal adhesive clean-up is required thus saving valuable chair time. Based on the results in this study, future in vivo investigation is suggested.

Objective: Evaluate the effect of crosshead speed, load cell configuration and curing time on shear bond strengths. Methods: 160 human molars were divided into equal groups of 20 second and 40 second photopolymerization times and then into 1kN or 10kN load cell groups. Each of the groups were divided into 0.5mm/min or 5mm/min crosshead speeds. Results: Regarding photopolymerization time (20s vs. 40s) and crosshead speeds (0.5mm/min vs. 5.0mm/min) there were no significant differences in SBS (p>0.05). The load cell configuration (1kN vs. 10kN) however showed statistically significant differences (p<0.05) with the 1kN producing higher bond strengths.

Thesis (Ph.D.)(Applied Mathematics)--University of Pretoria, 2000. / Includes summary. Includes bibliographical references.

Mainz, Universiẗat, Diss., 2003.

Thesis (Ph. D.)--Ohio State University, 1987. / Includes bibliographical references (leaves 117-119). Available online via OhioLINK's ETD Center.

abstract: This paper examines dealers' inventory holding periods and the associated price markups on corporate bonds from 2003 to 2010. Changes in these measures explain a large part of the time series variation in aggregate corporate bond prices. In the cross-section, holding periods and markups overshadow extant liquidity measures and have significant explanatory power for individual bond prices. Both measures shed light on the credit spread puzzle: changes in credit spread are positively correlated with changes in holding periods and markups, and a large portion of credit spread changes is explained by them. The economic effects of holding periods and markups are particularly sharp during crisis periods. / Dissertation/Thesis / Ph.D. Business Administration 2012

Nltrogen-15 isotope effects have been measured In the simple bond formation reactions of triethylamine with methyl iodide, triethylamine with ethyl iodide and triethylamine with ethyl bromide. Tests have been performed, to establish that the reactions were unidirectional under the experimental conditions and that the chemical procedures used to convert the quaternary ammonium salts to molecular nitrogen proceeded quantitatively. The mass spectrometer data were examined by rigorous statistical tests. At 6°C. the values of the ratio of rate constants, k14/k15, were: triethylamine-methyl iodide, 1.0009 +/- 0.0005; triethylamine-ethyl iodide, 1.0007 ±0.0006; trimethylamine-ethyl bromide, 0.9994 ±0.0006. For the reaction of triethylamine with ethyl iodide the value of k14/k15 increased slightly with increasing temperature. The results have been discussed in terms of the Bigeleisen theory of isotope effects with particular reference to the correct form for the effective mass term. / Thesis / Doctor of Philosophy (PhD)

No description available.

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Reinforced concrete structures deteriorate throughout their lifetime. This is particularly apparent in structures subjected to aggressive environments, which results in corrosion of reinforcing steel. Designers make allowances for accelerated deterioration in these environments in an attempt to ensure the durability of the structure. To combat corrosion, improved concrete characteristics and additional concrete cover are used to increase the protection provided by concrete to reinforcing. In spite of these measures, cracking of structures in service and from natural hazards can limit the effectiveness that these measures provide. Ultimately, this results in structures suffering from corrosion, which affects their strength, stiffness, and ductility. While strength reduction can be associated directly with a reduction in bar area, impacts on stiffness and ductility are associated with more complex mechanisms, one of which is bond deterioration. A key assumption in reinforced concrete design is that there is perfect bonding between steel reinforcing and surrounding concrete to allow for strain compatibility to be assumed. Perfect bond does not exist and diminished bond performance due to corrosion deterioration further violates this assumption, the effects of which are not fully understood. This thesis investigates the effects of bond deterioration due to corrosion on the seismic performance of reinforced concrete structures. 60 monotonic and cyclic pull-out tests were undertaken on corroded reinforced concrete specimens, with corrosion levels ranging from 0% to 25% reinforcing mass loss. Additional tests were also conducted on specimens with variations in the amount of confining steel to simulate losses in confinement associated with corrosion of confining steel. Experimental results were used to develop corrosion and confinement dependent cyclic bond-slip model. The proposed bond-slip model was then used to modelling pull-out of reinforcing bars detailed in accordance with New Zealand design standard NZS3101. Analyses were performed at a range of corrosion levels, levels of confinement, and uncorroded bond strengths. These showed that pull-out of reinforcement occurred at as little as 8% corrosion in low strength, unconfined conditions. Multi-spring modelling of standard reinforced concrete columns, representing a bridge pier to foundation connection, was performed at the full range of deterioration with allowance for bond slippage. These analyses showed significant reductions in stiffness occurring with increased corrosion levels as well as reduced ductility and possible pull-out of reinforcement.