We have prepared a new class of polybenzoxazine based nanocomposites through DNA-like self-complementary multiple hydrogen bonding. At first, benzoxazine containing thymine (Bz-T), PEO containing adenine (PEO-A) group and POSS containing adenine (POSS-A) have been successfully synthesized, respectively. Those chemical structures were confirmed by 1H and 13C NMR and FT-IR spectroscopies. DSC and TGA analyses showed that the Bz-T had lower cross-link temperature and higher thermostability than benzoxazine containing methyl acrylate (BZ-ac) group. Moreover, TEM and WAXD provided a new evidence for linearly structure and self-assembly polybenzoxaine through self-complementary multiple hydrogen bonding of its T units. Then, PEO-A/PBz-T and POSS-A/PBz-T hybrid materials were prepared. SAX, WAXD, TEM and AFM analyses indicated that the size of PEO domain in PBz-T matrix was significantly decreased and the new type phase separation boundary (discrete domain through non-convent bonds) was obtained. Finally, we were using WAXD, TEM, DSC and nanoindenter to study properties of POSS-A/PBz-T nanocomposite. The presence of self-assembly nano-lamellate structure and enhance the mechanical properties on thin film, because of well-dispersion of POSS in PBz-T matrix through strong hydrogen bonding between A-T interactions.

Thesis (M.S.)--University of North Carolina at Wilmington, 2004. / Includes bibliographical references (leaves : [56]-57).

Thesis (M.Sc.(Odontology))--University of Pretoria, 2009. / Includes bibliographical references (leaves 75-101).

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003. / Includes bibliographical references (leaves 129-132). Also available in electronic version. Access restricted to campus users.

Noncovalent and reversible covalent interactions have long been exploited in catalysis and supramolecular chemistry. Examples of such noncovalent interactions include hydrogen bonding, halogen bonding and CH-π and π-π interactions. Reversible covalent interactions that have been employed towards these ends comprise the formation of imines, acetals, ketals and boronate esters. This thesis describes the investigation of various noncovalent and reversible covalent interactions, and their possible applications in catalysis and novel reaction development. Chapter 1 describes the investigation of anion receptors composed of hydrogen- and halogen- bond donor groups. Binding studies of these molecules have indicated that they are capable of interacting with an anion simultaneously through hydrogen and halogen bonding. Receptor design was found to have a profound effect on the strength of the halogen bonding interaction. Receptors containing halogen-bond donors showed selectivity for halide anions over oxyanions. In Chapter 2, potential halogen bonding catalysts were synthesized and screened in a series of reactions. Incorporating halogen-bond donors into the catalysts appeared to have no beneficial effect in terms of reactivity. Explanations for these observations are discussed along with suggestions for designing future catalysts that could exploit halogen bonding interactions. Chapter 3 discusses attempts to use hydrogen-bond donor catalysts to effect catalyst-controlled stereoselective additions to 2-nitroglycals. While stereoselective additions were observed in some cases, they were not catalyst-controlled. The results from these experiments suggested that catalysts and reactions developed for simple nitroalkenes could not be easily adapted to 2-nitroglycal substrates. A review of interactions between boron containing compounds and saccharides is presented in Chapter 4. Their applications in drug delivery systems, cellular imaging and the sensing and separation of carbohydrates are discussed, in addition to their uses as protecting and activating groups in oligosaccharide synthesis. Finally in Chapter 5, the development of a regioselective boronic acid-mediated glycosylation reaction is described. This methodology was applied in the synthesis of two key intermediates used in the synthesis of a pentasaccharide derivative isolated from the plant Spergularia ramosa.

Noncovalent and reversible covalent interactions have long been exploited in catalysis and supramolecular chemistry. Examples of such noncovalent interactions include hydrogen bonding, halogen bonding and CH-π and π-π interactions. Reversible covalent interactions that have been employed towards these ends comprise the formation of imines, acetals, ketals and boronate esters. This thesis describes the investigation of various noncovalent and reversible covalent interactions, and their possible applications in catalysis and novel reaction development. Chapter 1 describes the investigation of anion receptors composed of hydrogen- and halogen- bond donor groups. Binding studies of these molecules have indicated that they are capable of interacting with an anion simultaneously through hydrogen and halogen bonding. Receptor design was found to have a profound effect on the strength of the halogen bonding interaction. Receptors containing halogen-bond donors showed selectivity for halide anions over oxyanions. In Chapter 2, potential halogen bonding catalysts were synthesized and screened in a series of reactions. Incorporating halogen-bond donors into the catalysts appeared to have no beneficial effect in terms of reactivity. Explanations for these observations are discussed along with suggestions for designing future catalysts that could exploit halogen bonding interactions. Chapter 3 discusses attempts to use hydrogen-bond donor catalysts to effect catalyst-controlled stereoselective additions to 2-nitroglycals. While stereoselective additions were observed in some cases, they were not catalyst-controlled. The results from these experiments suggested that catalysts and reactions developed for simple nitroalkenes could not be easily adapted to 2-nitroglycal substrates. A review of interactions between boron containing compounds and saccharides is presented in Chapter 4. Their applications in drug delivery systems, cellular imaging and the sensing and separation of carbohydrates are discussed, in addition to their uses as protecting and activating groups in oligosaccharide synthesis. Finally in Chapter 5, the development of a regioselective boronic acid-mediated glycosylation reaction is described. This methodology was applied in the synthesis of two key intermediates used in the synthesis of a pentasaccharide derivative isolated from the plant Spergularia ramosa.

No description available.

No description available.

New phosphine ligands which also contained crown ether groups were synthesized by condensing two main reagents. Reagent A was Ph2P(CH2)3NH2 and it was prepared by reductingPh2P(CH2)2CN with LiALH4 in diethyl ether. Ph2P(CH2)2CN is obtained by reacting Ph2PH and CH2=C(H)CN in a Michael-type reaction. Reagent B, 4-formyl-benzo-15-crown-5, was obtained from the reaction of 3,4 dihydroxybenzaldehyde with 1,11 dichloro-3,6,9 trioxoundecane.By condensing the benzaldehyde crown ether and the phosphine amine, a Schiff-base type crown ether containing both P(III) and N(III) centers was obtained. Spectroscopic studies of the ligand and its Pd(II) derivative have shown PdCl2[Ph2P.(CH2)3N CH-C6H3(OMe)2]2 were characterized by that metal binding occurred exclusively on the P( III) center.A model ligand was synthesized by condensing 3,4-dimethoxybenzaldehyde with Ph2P(CH2)3NH2 to obtain an analogous product. Both ligands, Ph2P(CH2)3N=CH-benzo-15crown-5 and Ph2P(CH2)3N=CH -C6H3(OMe)2 and their palladium derivatives, PdCl2[Ph2P(CH2)3N=CH-benzo-15-crown-5]2 and spectroscopic and elemental analysis. The Pd(II) derivatives were synthesized from the reactions of (Ph2CN)2)PdC12 with the ligands. / Department of Chemistry

The focus of the study is on the effect of massage on an infant's stress level, development and the emotional bond between the infant and the mother. Eight mother-infants dyads were recruited and the infants were between the ages of 3 to 9 months. The dyads were paired to ensure similarity of the groups and divided into an experimental and control group. The research made use of a multi-method, pre and post-test design. The measures used during the pre and post-testing included a biographical questionnaire, the Griffiths Mental Development Scales, the Parenting Stress Index and the Mother-to-lnfant Bonding Scale. Personal interviews were conducted with each mother as part of the post-test procedures. Saliva samples from every mother and infant were retrieved on three separate occasions to determine cortisol levels before, during and after the intervention. The experimental group's mothers received training to perform infant massage and were requested to massage their infants at least four times a week for the duration of four months. The data was processed by the Statistical Consultation Service of the Northwest University at Potchefstroom. The non-parametric test, Mann-Whitney U Test, was used to determine any statistical and/or practical significant differences between the experimental and control group before and after implementation of the intervention. The non-parametric test, Wilcoxon Matched-Pairs Signed Rank T-Test, was used to determine the differences within both the experimental and control group. Friedman's ANOVA was used to determine the changes within the groups regarding cortisol levels. As the sample size for this study is small and the possibility of determining statistical significance was slight, the effect sizes were considered for this study. The study had six aims. The first aim focused on the effect of infant massage on the infants' stress levels as measured through cortisol. No statistical significance could be found and the results revealed that the experimental group's infants' stress levels did not decrease. The second aim investigated the effect of infant massage on the mothers' stress levels as measured on the Parenting Stress Index and cortisol levels. No statistical significance could be determined but practical significant differences on the Parenting Stress Index indicated decreased maternal stress levels in the experimental group. These results differ from the cortisol levels that revealed the experimental group's mothers to experience higher levels of stress. The third aim focused on the effect of infant massage on the bond between mother and infant and found that the bond improved due to the intervention. The fourth aim investigated the effect of massage on the infants' development and although no statistical significance could be determined, practical significance could be found, indicating improvements on the motor scales for the experimental group. The fifth aim explored the mothers' subjective experience of infant massage as reported through qualitative measures. The sixth aim compared the mothers as participants' experience of infant massage as reported through quantitative measures and through qualitative measures. Strengths of the study included making use of a multi-method design and following a multi-disciplinary approach. Limitations of the study included a small sample size, the participants' restricted background and difficulty to ensure that the participants comply with the instructions for sampling saliva. Based on the results from the study, it can be concluded that infant massage have an effect on the mother-infant relationship, the mothers' subjective view of their stress levels and specified areas of the infants' development. According to the results from this study infant massage did not have an effect on the infants and mothers' stress levels as measured through cortisol. / Thesis (M.Sc. (Psychology))--North-West University, Potchefstroom Campus, 2009.