Control of Particle Properties in Thermally-Induced Precipitation of Polyetherimide.

The feasibility of thermally-induced phase separation and crystallization for the production of semi-crystalline polyetherimide (PEI) microparticles from an amorphous feedstock has been reported recently. Here, we investigate process parameter dependencies for designing and control of particle properties. A stirred autoclave was used to extend the process controllability, as the applied process parameters, e.g., stirring speed and cooling rate, were adjusted. By increasing the stirring speed, the particle size distribution was shifted to larger values (correlation factor ρ = 0.77). Although, the enhanced droplet breakup, induced by the higher stirring speed, led to the formation of smaller particles (ρ = -0.68), broadening the particle size distribution. The cooling rate showed a significant influence on the melting temperature, reducing it with a correlation factor of ρ = -0.77, as confirmed by differential scanning calorimetry. Lower cooling rates led to larger crystalline structures and enhanced the degree of crystallinity. The polymer concentration mainly affected the resulting enthalpy of fusion, as an increased polymer fraction enhanced the latter (correlation factor ρ = 0.96). In addition, the circularity of the particles was positively correlated to the polymer fraction (ρ = 0.88). The structure assessed via X-ray diffraction, was not affected.

Limited access to family-based addiction prevention services for socio-economically deprived families in Switzerland: a grounded theory study.

BACKGROUND: Families living in poor socio-economic circumstances, already confronted with social and health inequalities, are often not reached by family-based addiction prevention services. Besides quantitative models and health literacy approaches, qualitative research is lacking that could shed light on the exact circumstances and processes that lead to hindered addiction prevention service uptake by these families. Drawing on the concept of candidacy, we therefore reconstructed how socio-economically deprived parents and their (pre) adolescent children in the German-speaking part of Switzerland (non-)identified their candidacy for family-based addiction prevention services. METHODS: Following grounded theory, we collected and analysed data in an iterative-cyclical manner using theoretical sampling and theoretical coding techniques. Sixteen families with children aged 10-14 years were interviewed in depth (parent/s and child separately). All but one family lived below the at-risk-of-poverty threshold. RESULTS: Socio-economically deprived families' modes of recognizing and handling problems in everyday life were found to be core phenomena that structure the process towards (non) identification of candidacy for family-based addiction prevention services. Four modes anchored within socio-demographic resources were found: Families with mode A perceived their current life situation as existentially threatening and focused daily coping on the main pressing problem. Others (mode B) perceived prevalent multiple problems as normal (now); problems were normalized, often not recognized as such. In mode C families, problems were pragmatically recognized at a low threshold and pragmatically dealt with, mostly within the family. In mode D families, problems were constantly produced and dealt with early by the worried and anxious parents monitoring their child. From modes D to A, vulnerability increased concerning non-identification of candidacy for family-based addiction prevention services. Further, thematic relevance of addiction prevention, past experience with offers, integration in systems of assistance, strategies to protect the family, and families' search for information influenced whether identification of candidacy took place. CONCLUSIONS: Socio-economically deprived families differ in modes of problem construction and handling in everyday life; this differently opens up or closes routes to family-based addiction prevention. Addiction prevention practice should build on a bundle of diverse strategies for outreach to these families, stressing especially interventions on the structural and environmental level.

Participation of adults with cognitive, physical, or psychiatric impairments in family of origin and intimate relationships: a grounded theory study.

BACKGROUND: How adults with disabilities perceive participation has received little attention. Our purpose was to formulate a grounded theory on participation, based on the subjective experience of adults with cognitive, physical, or psychiatric impairment(s), and to identify barriers, facilitators, and support needs concerning participation in different areas of life. We aimed to explore whether the United Nations' Convention on the Rights of Persons with Disabilities (CRPD), ratified by Switzerland in 2014, and its principles are being met. Here we report on the main category and focus on the participation areas 'family of origin' and 'intimate relationships.' METHODS: In a qualitative, grounded theory study, we conducted problem-centered interviews with 23 adults with cognitive, physical, or psychiatric impairments (30-53 years; 11 men, 12 women), with different housing (on their own, assisted living, with parents) and work situations (primary vs. secondary labor market) in nine German-speaking Swiss cantons. RESULTS: Participation can be understood as a continuum that extends on a horizontal level (from participation is restricted to participation takes place) and a vertical level (separative setting vs. inclusive setting). In separative as well as in inclusive settings, diverse levels of participation are possible. Many participants were stuck in an 'in-between' area between separative and inclusion-oriented settings. In the family of origin, there was a thin line between fulfilling relations that enhance participation and conflictual relations and overprotective parenting that limit participation. In intimate relationships, opportunities for participation were limited overall. Many interviewees were single. Social environment and family of origin (e.g., parents) can enable and facilitate intimate relationships and sexual contacts but can also be an important barrier. CONCLUSIONS: Participation can be understood as a continuum. Participation restrictions exist in separative as well as in inclusive-oriented settings, also in the areas of family of origin and intimate relationships. Participation barriers must be torn down in separative as well as in inclusion-oriented settings. Trajectories to inclusive settings should be facilitated. Families with children with impairment(s) should be supported from early on to create the best possible participation possibilities for the (adult) person with impairment(s) and to support the family of origin itself.

Development of a solvent-free polylactide/calcium carbonate composite for selective laser sintering of bone tissue engineering scaffolds.

Since large bone defects cannot be healed by the body itself, continuous effort is put into the development of 3D scaffolds for bone tissue engineering. One method to fabricate such scaffolds is selective laser sintering (SLS). However, there is a lack of solvent-free prepared microparticles suitable for SLS. Hence, the aim of this study was to develop a solvent-free polylactide/calcium carbonate composite powder with tailored material properties for SLS. Four composite powders with a composition of approximately 75 wt% polylactide (PLLA as well as PDLLA) and 25 wt% calcium carbonate (calcite) were prepared by a milling process based on GMP standards. Four different grades of polylactide were chosen to cover a broad inherent viscosity range of 1.0-3.6 dl/g. The composite material with the lowest inherent viscosity (1.0 dl/g) showed the best processability by SLS. This was caused by the small polymer particle diameter (50 µm) and the small zero-shear melt viscosity (400 Pa·s), which led to fast sintering. The SLS process parameters were developed to achieve low micro-porosity (approx. 2%) and low polymer degradation (no measurable decrease of the inherent viscosity). A biaxial bending strength of up to 75 MPa was achieved. Cell culture assays indicated good viability of MG-63 osteoblast-like cells on the SLS specimens. Finally, the manufacture of 3D scaffolds with interconnected pore structure was demonstrated. After proving the biocompatibility of the material, the developed scaffolds could have great potential to be used as patient-specific bone replacement implants.

Unexpected formation and structural characterisation of a novel rhodium B12 analogue.

The metalation reactions of the 2,2'-bidipyrrin 4 with different rhodium(I) precursors yield the complexes 5 and 6 and the unusual corrinoid 7, depending only on the type of the ancillary ligand employed.