Formulation/cure technology for ultrahigh molecular weight silphenylene-siloxane polymers

Molecular weights above one million were achieved for methylvinylsilphenylene-siloxane terpolymers using a two-stage polymerization technique which was successfully scaled up to 200 grams. The resulting polymer was vulcanized by two different formulations and compared to an identically formulated commercial methylvinyl silicone on the basis of ultimate strength, Young's modulus, percent elongation at failure, and tear strength. Relative thermal/oxidative stabilities of the elastomers were assessed by gradient and isothermal thermogravimetric analyses performed in both air and nitrogen. The experimental elastomer exhibited enhanced thermal/oxidative stability and possed equivalent or superior mechanical properties. The effect of variations in prepolymer molecular weight on mechanical properties was also investigated

Ultra-high molecular weight silphenylene-siloxane polymers

Silphenylene-siloxane copolymers with molecular weights above one million were prepared using a two stage polymerization technique. The technique was successfully scaled up to produce 50 grams of this high polymer in a single run. The reactive monomer approach was also investigated using the following aminosilanes: bis(dimethylamino)dimethylsilane, N,N-bis(pyrrolidinyl)dimethylsilane and N,N-bis(gamma-butyrolactam)dimethylsilane). Thermal analyses were performed in both air and nitrogen. The experimental polymers decomposed at 540 to 562 C, as opposed to 408 to 426 C for commercial silicones. Differential scanning calorimetry showed a glass transition (Tg) at -50 to -55 C for the silphenylene-siloxane copolymer while the commercial silicones had Tg's at -96 to -112 C

Exploring the Perceived Barriers to Following a Mediterranean Style Diet in Childbearing Age: A Qualitative Study.

A considerable amount of research has focused on interventions in pregnancy to promote health in current and future generations. This has yielded inconsistent results and focus has turned towards improving health in the preconception period. Promotion of healthy dietary patterns similar to a Mediterranean diet in the preconception years has been suggested as a dietary strategy to prevent maternal obesity and optimize offspring health. However, it is uncertain whether adoption is acceptable in women of childbearing age. This qualitative study aims to investigate the perceived barriers to following a Mediterranean diet in women of childbearing age. Semi-structured focus groups were used to generate deep insights to be used to guide the development of a future intervention. Nulliparous women aged between 20 and 47 years were recruited (n = 20). Six focus groups were digitally audio recorded and transcribed verbatim by the researcher. Thematic analysis was used to analyze data, which occurred in parallel with data collection to ascertain when data saturation was reached. Five core themes were identified: Mediterranean diet features, perceived benefits, existing dietary behavior and knowledge, practical factors, and information source. The present study highlights that a Mediterranean diet is acceptable to childbearing-aged women, and the insights generated will be helpful in developing an intervention to promote Mediterranean diet adoption

Defining the latent phase of labour: is it important?

Background and rationale: The latent phase of labour is recognised as a period of uncertainty for both women and midwives. There is evidence from the literature of considerable variation in labour definitions and practice. Stimulated by discussion at an international maternity research conference, we set out to explore opinions regarding the need for labour stage definitions. Aim: to identify health professionals’ views regarding the need for a definition of the onset and the end of the latent phase of labour. Methods: This was an opportunistic, semi-structured, online survey of attendees at a maternity care research conference, which included midwives, other clinicians, academics, advocates and user representatives. Attendees (approximately 100) were invited to participate through a single email invitation sent by the conference committee and containing a link to the survey. Consent was sought on the landing page. Ethical approval was obtained from Bournemouth University’s research ethics committee. Quantitative questions were analysed using simple descriptive statistics using IBM SPSS Statistics Version 24. Open questions were analysed using content analysis and where participants gave a more detailed answer, these were analysed using a thematic approach. Findings: Participants in the survey (n = 21) came from twelve countries. Most of the participants thought that there was a need to define the onset of the latent phase (n = 15, 71%). Common characteristics were cited, but the main theme in the open comments referred to the importance of women’s perceptions of labour onset. Most participants (n = 18, 86%) thought that there was a need to define the end of the latent phase. This was felt necessary because current practice within facilities is usually dictated by a definition. The characteristics suggested were also not unexpected and there was some consensus; but the degree of cervical dilatation that signified the end of the latent phase varied among participants. There was significant debate about whether a prolonged latent phase was important; for example, was it associated with adverse consequences. Most participants thought it was important (n = 15, 71%), but comments indicated that the reasons for this were complex. Themes included the value that women attached to knowing the duration of labour and the need to support women in the latent phase. Implications for practice: The findings from this small, opportunistic survey reflect the current debate within the maternal health community regarding the latent phase of labour. There is a need for more clarity around latent phase labour (in terms of both the definition and the support offered) if midwives are to provide care that is both woman centred and evidence-based. The findings will inform the development of a larger survey to explore attitudes towards labour definitions

"Is it realistic?" the portrayal of pregnancy and childbirth in the media.

BACKGROUND: Considerable debate surrounds the influence media have on first-time pregnant women. Much of the academic literature discusses the influence of (reality) television, which often portrays birth as risky, dramatic and painful and there is evidence that this has a negative effect on childbirth in society, through the increasing anticipation of negative outcomes. It is suggested that women seek out such programmes to help understand what could happen during the birth because there is a cultural void. However the impact that has on normal birth has not been explored. METHODS: A scoping review relating to the representation of childbirth in the mass media, particularly on television. RESULTS: Three key themes emerged: (a) medicalisation of childbirth; (b) women using media to learn about childbirth; and (c) birth as a missing everyday life event. CONCLUSION: Media appear to influence how women engage with childbirth. The dramatic television portrayal of birth may perpetuate the medicalisation of childbirth, and last, but not least, portrayals of normal birth are often missing in the popular media. Hence midwives need to engage with television producers to improve the representation of midwifery and maternity in the media

Clean birth kits to improve birth practices: development and testing of a country level decision support tool

Background: Clean birth practices can prevent sepsis, one of the leading causes of both maternal and newborn mortality. Evidence suggests that clean birth kits (CBKs), as part of package that includes education, are associated with a reduction in newborn mortality, omphalitis, and puerperal sepsis. However, questions remain about how best to approach the introduction of CBKs in country. We set out to develop a practical decision support tool for programme managers of public health systems who are considering the potential role of CBKs in their strategy for care at birth. Methods: Development and testing of the decision support tool was a three-stage process involving an international expert group and country level testing. Stage 1, the development of the tool was undertaken by the Birth Kit Working Group and involved a review of the evidence, a consensus meeting, drafting of the proposed tool and expert review. In Stage 2 the tool was tested with users through interviews (9) and a focus group, with federal and provincial level decision makers in Pakistan. In Stage 3 the findings from the country level testing were reviewed by the expert group. Results: The decision support tool comprised three separate algorithms to guide the policy maker or programme manager through the specific steps required in making the country level decision about whether to use CBKs. The algorithms were supported by a series of questions (that could be administered by interview, focus group or questionnaire) to help the decision maker identify the information needed. The country level testing revealed that the decision support tool was easy to follow and helpful in making decisions about the potential role of CBKs. Minor modifications were made and the final algorithms are presented. Conclusion: Testing of the tool with users in Pakistan suggests that the tool facilitates discussion and aids decision making. However, testing in other countries is needed to determine whether these results can be replicated and to identify how the tool can be adapted to meet country specific needs

Thermal stability of sputter-deposited 330 austenitic stainless-steel thin films with nanoscale growth twins

We have explored the thermal stability of nanoscale growth twins in sputter-deposited 330 stainless-steel (SS) films by vacuum annealing up to 500 °C. In spite of an average twin spacing of only 4 nm in the as-deposited films, no detectable variation in the twin spacing or orientation of twin interfaces was observed after annealing. An increase in the average columnar grain size was observed after annealing. The hardness of 330 SS films increases after annealing, from 7 GPa for as-deposited films to around 8 GPa for annealed films, while the electrical resistivity decreases slightly after annealing. The changes in mechanical and electrical properties after annealing are interpreted in terms of the corresponding changes in the residual stress and microstructure of the films

Solid Propulsion Systems, Subsystems, and Components Service Life Extension

The service life extension of solid propulsion systems, subsystems, and components will be discussed based on the service life extension of the Space Transportation System Reusable Solid Rocket Motor (RSRM) and Booster Separation Motors (BSM). The RSRM is certified for an age life of five years. In the aftermath of the Columbia accident there were a number of motors that were approaching the end of their five year service life certification. The RSRM Project initiated an assessment to determine if the service life of these motors could be extended. With the advent of the Constellation Program, a flight test was proposed that would utilize one of the RSRMs which had been returned from the launch site due to the expiration of its five year service life certification and twelve surplus Chemical Systems Division BSMs which had exceeded their eight year service life. The RSRM age life tracking philosophy which establishes when the clock starts for age life tracking will be described. The role of the following activities in service life extension will be discussed: subscale testing, accelerated aging, dissecting full scale aged hardware, static testing full scale aged motors, data mining industry data, and using the fleet leader approach. The service life certification and extension of the BSMs will also be presented