This study examines the relationship between maternal emotional attachment to the fetus, beliefs about fetal health locus of control, and use of prenatal testing (i.e., amniocentesis and maternal serum screening). To date, no research has directly addressed the link between these psychosocial variables and prenatal testing uptake. Ninety-one pregnant women at risk for fetal abnormalities (i.e., 35 years of age or older) participated in the study, of whom 35 had no testing, 27 had serum screening, and 29 had amniocentesis in their current pregnancy. Results of a hierarchical multiple regression partially supported the hypothesis that internal and powerful others Fetal Health Locus of Control (Labs & Wurtele, 1986) and prenatal testing status would be predictive of attachment (Prenatal Attachment Inventory; Muller, 1993) over and above the effects of gestational age, maternal age and attitude toward abortion. Fetal Health Locus of Control beliefs regarding ones own role (FHLC-I) in determining the health of ones fetus were found to be predictive of prenatal attachment. Results failed to support the hypothesis that the role of health professionals (FHLC-P) would be predictive of prenatal attachment. As predicted, women who had not used prenatal testing or who underwent amniocentesis tended to have stronger prenatal attachment than those who underwent serum screening only. Results supported the hypotheses that stronger attachment to the fetus would be positively correlated with both FHLC-I and FHLC-P scores. Women who had no testing were found to hold less favourable attitudes toward abortion and rate their religious as stronger than those who had amniocentesis. Emotional attachment to the fetus was stronger among women who had previous miscarriages than those who had not, but did not differ between women who had a previous abortion and those who had not.

Fibre-reinforced-polymer (FRP) composites have been widely used for the flexural strengthening of reinforced concrete (RC) structures. Flexural strengthening methods with FRP include external bonding of FRP composites (EB system) and insertion of FRP strips or bars into grooves cut into the concrete (near-surface-mounted or NSM system). Recently, a prestressed FRP strengthening system has been developed and investigated, whereby the FRP reinforcement is pretensioned prior to attachment to the concrete to maximize the use of the high tensile strength of the FRP reinforcement. Existing studies have shown that the ultimate load carrying capacity and serviceability were greatly improved in FRP flexural strengthened beams. However, the only disadvantage of the FRP strengthening system is the reduction of deformability compared to that of unstrengthened structures due to the limited strain capacity of the FRP reinforcement and premature debonding failure. Structures with low deformability may fail suddenly without warning to evacuate, resulting in catastrophic failure. Therefore, a study on the improvement of deformability is critical for the effective use of FRP strengthening systems. In this study, a partially bonded concept is introduced and applied to various FRP strengthening methods, with the specific objective of increasing deformability in FRP strengthened beams. The FRP reinforcement is usually completely bonded to the concrete tensile surface, while a portion of the FRP length is intentionally unbonded in the partially bonded system in order to improve deformability while sustaining high load carrying capacity. To investigate the general behaviour of the partially bonded system, a new analytical model has been developed because conventional section analysis used for analysis of the fully bonded system is not applicable due to strain incompatibility at the FRP reinforcement level within the unbonded length. The analysis shows that a partially bonded system has a high potential to improve deformability without the loss of strength capacity. An extensive experimental program was conducted to verify the analytical model and to investigate the actual behaviour of the partially bonded beams. A total of seventeen, 3.5m long, RC T-beams were constructed and tested. One of them is an unstrengthened control beam, while the other 16 beams consist of four test groups that were strengthened by different strengthening methods: non-prestressed EB, non-prestressed NSM, 40% prestressed NSM, and 60% prestressed NSM. To allow investigation of the effect of partially unbonding, each group has different unbonded lengths and includes a fully bonded beam. For the non-prestressed EB strengthened beams, the failure mode of all beams was premature FRP debonding failure without regard to the bond condition. The ultimate strength and the ultimate deformability of the partially bonded beams were improved compared to the fully bonded beam. This was because the typical intermediate debonding failure that occurred in the fully bonded beam was avoided due to intentional unbonding in the partially bonded beams. The analytical model predicted the general behaviour of the EB strengthened beams well except at the ultimate response due to the premature debonding failure. A three-dimensional nonlinear finite element (FE) analysis was performed utilizing interfacial elements and contact modeling to investigate the debonding failure of this system. The FE analysis represented the behaviour of the debonding failure and bond stress distributions at FRP-concrete interface of both the fully bonded and partially bonded beams well. For the non-prestressed NSM strengthened beams, the premature debonding failure that occurred in the EB strengthened beams was not observed, and almost the full capacity of FRP was exhibited. Prominent stiffness reduction was observed in terms of load-deflection diagrams at the post-yielding stage with the increase of the unbonded length. This stiffness reduction increased the deformability of the partially bonded beams for a given applied load after steel yielding in comparison to the fully bonded beam. The FRP started to slip at high load levels and the concrete crushed gradually with a gradual loss of the beam’s cross-section, inducing nonlinear behaviour near the ultimate state of the beams. To address this behaviour, an advanced analytical model utilizing idealized section model and slip model is proposed to consider the FRP slip and concrete gradual failure. Prestressed NSM strengthened beams were very effective to improve the cracking load, to decrease the deflection at service load, and to increase the ultimate load compared to non-prestressed NSM strengthened beams. This improvement was greater as the prestressing level increased. The partially bonded prestressed beams showed an improvement in deformability compared to the fully bonded prestressed beams while minimizing the reduction of the ultimate load carrying capacity and serviceability. The partially bonded system was more effective to improve the deformability at higher levels of prestressing force. Based on the model developed, a parametric study was performed varying the main parameters. This showed that the FRP strengthened beam that has an FRP area (Af) less than the balanced FRP area (Af,b) of the beam has a high potential to improve the deformability as the unbonded length increases. The balanced FRP area is increased as the concrete strength and the FRP prestressing force are increased, or as the area of the steel reinforcement decreases. Finally, design recommendations and procedures are proposed for the effective use of the partially bonded system to improve the deformability of FRP strengthened concrete beams.

The construction of benzylic quaternary stereocentres via the enantioselective copper-catalyzed 1,4-addition of dialkylzinc reagents to Meldrum’s acid acceptors in the presence of a phosphoramidite ligand is reported. Meldrum’s acid acceptors can be easily accessed and numerous derivatives have been prepared to investigate the scope of the enantioselective 1,4-addition. The reaction is tolerant to a wide range of heteroaromatic and functional groups. The significance of substituting the position para, meta, and ortho to the electrophilic centre is also highlighted. Primary and secondary organozinc reagents are shown to be compatible in this reaction. A highly enantioselective synthesis of carboxylic acid derivatives having an -quaternary centre through copper-catalyzed 1,4-addition of dialkylzinc reagents to aryl acetate derivatives is also described. This method employs a commercially available phosphoramidite ligand and readily accessible Meldrum’s acid acceptors. A brief insight into the observed selectivity is also discussed. The significance of this method was established by the expedient preparation of chiral diesters, succinimides, γ-butyrolactones, and isocyanates from highly functionalized benzyl Meldrum’s acids. In addition to 1,4-addition, the enantioselective asymmetric synthesis of benzylic tertiary and quaternary stereogenic centres via 1,6-addition of dialkylzinc reagents to Meldrum’s acid acceptors is outlined. This work represents one of the early examples of 1,6-asymmetric conjugate addition reactions and discussions on the regioselectivity of the process are disclosed. On a different subject matter, the occurrence and persistence of C–H•••X (O, S, Br, Cl, and F) bond in solution using 1H NMR spectroscopy is discussed for a large number of benzyl Meldrum’s acids. The latter are novel and reliable probes for the evaluation of this type of non-classical interactions in solution. The persistence of the C–H•••X bond in solution is demonstrated to be dependent upon structural features present on the aromatic moiety and the benzylic position of the benzyl Meldrum’s acid derivatives. The observations presented highlight the large potential of Meldrum’s acid in developing an understanding of the function and nature of C–H•••X interactions.

Fibre-reinforced-polymer (FRP) composites have been widely used for the flexural strengthening of reinforced concrete (RC) structures. Flexural strengthening methods with FRP include external bonding of FRP composites (EB system) and insertion of FRP strips or bars into grooves cut into the concrete (near-surface-mounted or NSM system). Recently, a prestressed FRP strengthening system has been developed and investigated, whereby the FRP reinforcement is pretensioned prior to attachment to the concrete to maximize the use of the high tensile strength of the FRP reinforcement. Existing studies have shown that the ultimate load carrying capacity and serviceability were greatly improved in FRP flexural strengthened beams. However, the only disadvantage of the FRP strengthening system is the reduction of deformability compared to that of unstrengthened structures due to the limited strain capacity of the FRP reinforcement and premature debonding failure. Structures with low deformability may fail suddenly without warning to evacuate, resulting in catastrophic failure. Therefore, a study on the improvement of deformability is critical for the effective use of FRP strengthening systems. In this study, a partially bonded concept is introduced and applied to various FRP strengthening methods, with the specific objective of increasing deformability in FRP strengthened beams. The FRP reinforcement is usually completely bonded to the concrete tensile surface, while a portion of the FRP length is intentionally unbonded in the partially bonded system in order to improve deformability while sustaining high load carrying capacity. To investigate the general behaviour of the partially bonded system, a new analytical model has been developed because conventional section analysis used for analysis of the fully bonded system is not applicable due to strain incompatibility at the FRP reinforcement level within the unbonded length. The analysis shows that a partially bonded system has a high potential to improve deformability without the loss of strength capacity. An extensive experimental program was conducted to verify the analytical model and to investigate the actual behaviour of the partially bonded beams. A total of seventeen, 3.5m long, RC T-beams were constructed and tested. One of them is an unstrengthened control beam, while the other 16 beams consist of four test groups that were strengthened by different strengthening methods: non-prestressed EB, non-prestressed NSM, 40% prestressed NSM, and 60% prestressed NSM. To allow investigation of the effect of partially unbonding, each group has different unbonded lengths and includes a fully bonded beam. For the non-prestressed EB strengthened beams, the failure mode of all beams was premature FRP debonding failure without regard to the bond condition. The ultimate strength and the ultimate deformability of the partially bonded beams were improved compared to the fully bonded beam. This was because the typical intermediate debonding failure that occurred in the fully bonded beam was avoided due to intentional unbonding in the partially bonded beams. The analytical model predicted the general behaviour of the EB strengthened beams well except at the ultimate response due to the premature debonding failure. A three-dimensional nonlinear finite element (FE) analysis was performed utilizing interfacial elements and contact modeling to investigate the debonding failure of this system. The FE analysis represented the behaviour of the debonding failure and bond stress distributions at FRP-concrete interface of both the fully bonded and partially bonded beams well. For the non-prestressed NSM strengthened beams, the premature debonding failure that occurred in the EB strengthened beams was not observed, and almost the full capacity of FRP was exhibited. Prominent stiffness reduction was observed in terms of load-deflection diagrams at the post-yielding stage with the increase of the unbonded length. This stiffness reduction increased the deformability of the partially bonded beams for a given applied load after steel yielding in comparison to the fully bonded beam. The FRP started to slip at high load levels and the concrete crushed gradually with a gradual loss of the beam’s cross-section, inducing nonlinear behaviour near the ultimate state of the beams. To address this behaviour, an advanced analytical model utilizing idealized section model and slip model is proposed to consider the FRP slip and concrete gradual failure. Prestressed NSM strengthened beams were very effective to improve the cracking load, to decrease the deflection at service load, and to increase the ultimate load compared to non-prestressed NSM strengthened beams. This improvement was greater as the prestressing level increased. The partially bonded prestressed beams showed an improvement in deformability compared to the fully bonded prestressed beams while minimizing the reduction of the ultimate load carrying capacity and serviceability. The partially bonded system was more effective to improve the deformability at higher levels of prestressing force. Based on the model developed, a parametric study was performed varying the main parameters. This showed that the FRP strengthened beam that has an FRP area (Af) less than the balanced FRP area (Af,b) of the beam has a high potential to improve the deformability as the unbonded length increases. The balanced FRP area is increased as the concrete strength and the FRP prestressing force are increased, or as the area of the steel reinforcement decreases. Finally, design recommendations and procedures are proposed for the effective use of the partially bonded system to improve the deformability of FRP strengthened concrete beams.

The construction of benzylic quaternary stereocentres via the enantioselective copper-catalyzed 1,4-addition of dialkylzinc reagents to Meldrum’s acid acceptors in the presence of a phosphoramidite ligand is reported. Meldrum’s acid acceptors can be easily accessed and numerous derivatives have been prepared to investigate the scope of the enantioselective 1,4-addition. The reaction is tolerant to a wide range of heteroaromatic and functional groups. The significance of substituting the position para, meta, and ortho to the electrophilic centre is also highlighted. Primary and secondary organozinc reagents are shown to be compatible in this reaction. A highly enantioselective synthesis of carboxylic acid derivatives having an -quaternary centre through copper-catalyzed 1,4-addition of dialkylzinc reagents to aryl acetate derivatives is also described. This method employs a commercially available phosphoramidite ligand and readily accessible Meldrum’s acid acceptors. A brief insight into the observed selectivity is also discussed. The significance of this method was established by the expedient preparation of chiral diesters, succinimides, γ-butyrolactones, and isocyanates from highly functionalized benzyl Meldrum’s acids. In addition to 1,4-addition, the enantioselective asymmetric synthesis of benzylic tertiary and quaternary stereogenic centres via 1,6-addition of dialkylzinc reagents to Meldrum’s acid acceptors is outlined. This work represents one of the early examples of 1,6-asymmetric conjugate addition reactions and discussions on the regioselectivity of the process are disclosed. On a different subject matter, the occurrence and persistence of C–H•••X (O, S, Br, Cl, and F) bond in solution using 1H NMR spectroscopy is discussed for a large number of benzyl Meldrum’s acids. The latter are novel and reliable probes for the evaluation of this type of non-classical interactions in solution. The persistence of the C–H•••X bond in solution is demonstrated to be dependent upon structural features present on the aromatic moiety and the benzylic position of the benzyl Meldrum’s acid derivatives. The observations presented highlight the large potential of Meldrum’s acid in developing an understanding of the function and nature of C–H•••X interactions.

No description available.

No description available.

A novel methodology has been developed for the formation of block copolymers that combines ring-opening metathesis polymerization (ROMP) with functional chain-transfer agents (CTAs), functional chain-terminators (CTs) and self-assembly. Telechelic homopolymers of cyclooctene derivatives that are end-functionalized with hydrogen-bonding or metal-coordination sites are formed via the combination of ROMP with a corresponding functional CTA. These telechelic homopolymers are fashioned with a high control over molecular weight and without the need for post-polymerization procedures. The homopolymers undergo fast and efficient self-assembly with their complement homopolymer or small molecule analogues to form block copolymer architectures. The block copolymers have similar association constants to small molecule analogues described in the literature, regardless of size or the nature of the complementary unit or the polymer side-chain. The ROMP of side-chain functionalized norbornene polymers is coupled with functional CTs to produce block copolymer with main- and side-chain self-assembly sites. Combinations of these norbornene polymers with their complement polymer via self-assembly produce non-covalent AB type block copolymers fast and efficiently. ABA type block copolymers are realized by combining the difunctional homopolymer formed via the CTA pathway with the CT synthesized mono-functional polymer. These polymers show similar association constants regardless of the sequence of polymer formation.

The role of bonding in the tensile creep behavior of paper was analyzed. This was accomplished by producing handsheets at a range of different bonding levels through manipulation of relative bonded area and specific bond strength. This was done by varying the level of wet pressing (to change relative bonded area) and using debonding and bonding agents (to change specific bond strength). Once manufactured, sheets underwent an extensive battery of physical testing and creep testing. Creep testing was conducted under constant humidity and cyclic humidity (accelerated creep) conditions. Microscopic analysis techniques were also employed to visually study bonded area loss from creep strain. Two mathematical models (one empirical and one rheological) were created to isolate, account for, and incorporate bonding into predicting tensile creep behavior in paper. Overall, the results from this thesis show that the role of bonding in tensile creep behavior (and accelerated creep behavior) is no different than its role in stress-strain behavior, which is a new finding. This means the bonding influence on tensile creep behavior is related to sheet efficiency and how effectively stress is distributed within the structure, bonded area loss is a strain-induced phenomenon and bonding is not the cause of accelerated creep behavior.

The effect of laser power pattern on the temperature and thermal stress distributions in LED die bonding process is investigated in this work. The wavelength of 940nm diode laser source is used in this study. The laser light is focus on the back of an AlN substrate. The eutectic Au80Sn20 solder metallized between die and substrate is soldered by the heat conducted from the controlled laser power. The finite element package software-MSC. Marc is employed to simulate the laser soldering process. The thermal-elastic-plastic models of the solid elements are used. The temperature dependent material properties are applied to characterize the temperature variation effect during the die bonding. The measured temperature data have also been used to derive the absorption coefficient, conductivity, specific heat of AlN substrate and the convection coefficient in free convection via the inverse engineering process. A difference between the simulated and measured temperature can be kept in 10%. The temperature and thermal stress distributions during the die bonding process have been simulated and studied. The distributions of residual stress induced in this die bonding process have also been studied. The effects of different laser soldering parameters, e.g. focus shift, defocus, inclined angle, on the die bonding are also studied.