A study of hydrogen bonding in concentrated diol/water solutions by proton NMR correlations with glass formation

Solute/water interactions in a series of diol solutions have been investigated by ¹H NMR. Strong hydrogen bonding between water and alcohols that are more basic than water is thought to result in lower chemical shifts of water protons compared to the case of pure water. This is attributed to a greater degree of covalent character in the hydrogen bonding between water and the more basic diols. The inductive effect of the methyl group and longer chain alkyls is observed to increase basicity in ethylene glycol, propylene glycol, and 2,3-butanediol solutions. A correlation between the glass-forming ability of the diol solutions and the stronger hydrogen-bonding solutes (i.e., stronger bases) is developed, with 2,3-butanediol best promoting glass formation at the lowest concentrations.

Theoretical study on behaviour of superplastic forming/diffusion bonding of bulk metallic glasses

Based on the behaviour of the superplastic deformation of metallic glasses and Pilling’s model, a diffusion bonding model suitable for metallic glasses is proposed in the present study. In the current model, the diffusion bonding processes consists of two stages: one is the plastic deformation stage and the other is the void shrinkage stage, in which, the atom diffusion and superplastic deformation are responsible for the void shrinkage. Applying this model to the diffusion bonding of a Zr based metallic glass, the predicted bonding time is in good agreement with the experimental result. A map for determining the bonding temperature and time to achieve high quality bonding in a Zr based metallic glass is suggested.

Self-assembled diblock copolymer complexes via competitive hydrogen bonding

This thesis investigates self-assembly and microphase separation induced by competitive hydrogen bonding in A-b-BC diblock copolymer/homopolymer systems. A series of ordered and disordered morphologies including lamellae, hexagonal cylinders, wormlike microdomains and hierarchical structures were observed. The morphological transitions are correlated with hydrogen bonding interactions in terms of the association constants.

The role of attachment in current and future parent caregiving

Few studies have investigated how attachment bonds between older parents and their adult children influence adult children’s provision of care and older parents’ seeking of support from kin. The aim of this study was to investigate how the attachment orientations of adult children (N = 119) and older parents (N = 148) predict family caregiving and perceptions of carer burden. Across both samples (that were unrelated), attachment dimensions were associated with current and future caregiving and care receiving and perceptions of carer burden, even when accounting for demographic variables, parental dependence and filial obligation. Specifically, attachment avoidance was associated negatively with adult children’s future care of parents and positively with burden. In contrast, attachment anxiety was positively associated with older parents’ seeking current support, perceptions of carer burden, and intentions to seek future support.

Microphase separation through competitive hydrogen bonding in double crystalline diblock copolymer/homopolymer blends

Microphase separation induced by competitive hydrogen bonding interactions in double crystalline diblock copolymer/homopolymer blends was studied for the first time. Poly(ethylene oxide)- block-poly(e-caprolactone) (PEO-b-PCL)/poly(4-vinylphenol) (PVPh) blends were prepared in tetrahydrofuran. The diblock copolymer PEO-b-PCL consists of two immiscible crystallizable blocks wherein bothPEO and PCL blocks can form hydrogen bonds with PVPh. In these A-b-B/C diblock copolymer homopolymer blends, microphase separation takes place due to the disparity in intermolecular interactions; specifically, PVPh and PEO block interact strongly whereas PVPh and PCL block interact weakly. The TEM and SAXS results show that the cubic PEO-b-PCL diblock copolymer changes into ordered hexagonal cylindrical morphology upon addition of 20 wt % PVPh followed by disordered bicontinuous phase in the blend with 40 wt % PVPh and then to homogeneous phase at 60 wt % PVPh and above blends. Up to 40 wt % PVPh there is only weak interaction between PVPh and PCL due to the selective hydrogen bonding between PVPh and PEO. However, with higher PVPh concentration, the blends become homogeneous since a sufficient amount of PVPh is available to form hydrogen bonds with both PEO and PCL. A structural model was proposed to explain the self-assembly and microphase morphology of these blends based on the experimental results obtained. The formation of nanostructures and changes in morphologies depend on the relative strength of hydrogen bonding interaction between each block of the block copolymer and the homopolymer.

Being a parent on dialysis : a literature review

Aim
This literature review explored the extant literature to further our understanding of the experience of being a parent on dialysis.
Methods
Keywords used to search the literature were haemodialysis, hemodialysis, chronic kidney disease, end stage renal disease, parent and experience. Databases searched included CINAHL, Medline, Wiley/Blackwell, EBSCOHost, Web of Science, Pubmed, and ProQuest. Years included were 1999 to 2009. Seventeen primary research articles (sixteen qualitative, one mixed methods) met the search criteria with only one on parents undergoing dialysis.
Findings
The experience of the parent on dialysis has rarely been explored in the literature. Related research has indicated important themes including: restricted lives; relationships; adjustment; consequences and future outlook.
Conclusions
More should be known about challenges that face parents who receive dialysis. This review established an urgent need for further research to determine the experiences and needs of this population to provide empirical, person-centred nursing care.

Problematic placement : pathways pre-service teachers’ perspectives on their infant/toddler placement

The inclusion of an infant/toddler placement in a ‘pathways’ early childhood teaching degree, where students already have qualifications and experience in working with young children, can be problematic. This pilot study investigated student teachers’ views on their infant/toddler (birth-to-two-years) placement. Sixty-six students completing their early childhood education degree at an Australian university responded to a survey seeking their perspectives on the effectiveness of the placement in developing teacher confidence, knowledge and skills, and the quality of the supervision they received. The participants had entered their degree with a two-year Diploma of Children’s Services. Responses indicated significant dissatisfaction with the quality of supervision, the absence of teacher-mentors, and the lack of opportunities to practise new approaches. Participants commented that they ‘already knew’ how to work with this age group, and that they aspired to work with older children. The results align with other findings on factors associated with positive placements, and raise questions about the effectiveness of the infant/toddler placement in its current form.

Multiple vesicular morphologies in AB/AC diblock copolymer complexes through hydrogen bonding interactions

We report for the first time multiple vesicular morphologies in block copolymer complexes formed in aqueous media via hydrogen bonding interactions. A model AB/AC diblock copolymer system consisting of polystyrene-block- poly(acrylic acid) (PS-b-PAA) and polystyrene-block-poly(ethylene oxide) (PS-b-PEO) was examined using transmission electron microscopy, small-angle X-ray scattering, and dynamic light scattering. The complexation and morphological transitions were driven by the hydrogen bonding between the complementary binding sites on PAA and PEO blocks of the two diblock copolymers. Upon the addition of PS-b-PEO, a variety of bilayer aggregates were formed in PS-b-PAA/PS-b-PEO complexes including vesicles, multilamellar vesicles (MLVs), thick-walled vesicles (TWVs), interconnected compound vesicles (ICCVs), and irregular aggregates. Among these aggregates, ICCVs were observed as a new morphology. The morphology of aggregates was correlated with respect to the molar ratio of PEO to PAA. At [EO]/[AA] = 0.5, vesicles were observed, while MLVs were obtained at [EO]/[AA] = 1. TWVs and ICCVs were formed at [EO]/[AA] = 2 and 6, respectively. When [EO]/[AA] reached 8 and above, only irregular aggregates appeared. These findings suggest that complexation between two amphiphilic diblock copolymers is a viable approach to prepare polymer vesicles in aqueous media.

Parent participation in disadvantaged schools : moving beyond attributions of blame

Although facilitating community participation in disadvantaged schools can be difficult, this article argues that, given the structuring of schooling in contemporary western democracies, it is even more difficult than we might imagine. Drawing on Bourdieu, we attempt to elucidate the complex relations between schooling and socio·cultural contexts which can lead to inequalities of opportunity for parent participation in schooling and which work to maintain disadvantage for marginalised students. Recognitive justice, with its positive regard for social difference and centrality of social democratic processes, offers us another way of advancing this discussion beyond simplistic attributions of blame. In particular, a polities of recognition is concerned with opening up the processes of schooling to groups who often have been excluded. This article uses interview data from a small Australian secondary school located in a regional community with high welfare dependency and a large indigenous population.