Importance of grain boundary diffusion : an experimental study

This research is concerned with the mechanisms of diffusion in the Earth and the implications of such an understanding. Specifically, this work is concerned with one particular aspect of diffusion: Grain Boundary Diffusion (GBD). An experimental investigation of GBD has been conducted by considering three specific scenarios; GBD of H in stoichiometric Mg-spinel, GBD of Ti in Quartz and GBD of Li in olivine. By considering the GBD of three very different elements it has been possible to synthesise an understanding of some of the mechanisms involved in the process. GBD is potentially a very important process within the Earth with wide ranging implications. Grain boundaries may provide fast pathways for transportation of a range of compatible and incompatible diffusing species in the Earth’s interior – potentially acting as storage locations and also as efficient pathways between different geological reservoirs. It is also potentially very important in the application of a number of techniques including dating and geothermometry and geobarometry. Here, an experimental study of the GBD of H has been carried out with the overall finding that GBD appears to occur at slightly greater yet broadly similar rates to lattice diffusion. This finding is considered in terms of the mantle properties which are affected by the presence and transport of H. A follow up series of experiments was conducted looking at Li diffusion. Li was chosen due to its volatile nature and larger atomic radius as compared to H. As such, it provided a useful test of the hypothesis that the radius of a diffusant might affect its chosen method of diffusion. A third set of experiments were carried out to investigate the GBD of Ti in quartz with particular reference to the TitaniQ geothermo(baro)meter. This set of experiments provided a very useful comparison to the data which had previously been obtained from lighter elements. This investigation has found that a combination of factors including charge, diffusant diameter and the specific mineralogical characteristics of the host phase will define the dominant diffusive mechanism and the size of the contribution made by that mechanism towards observed bulk diffusivities. A characterisation of the temperature dependency of diffusion within each setting has also been completed. As such, it also makes a useful contribution to the current dataset for GBD

Pollen-pistil interactions and self-incompatibility in the Asteraceae: new insights from studies of Senecio squalidus (Oxford ragwort)

Background Pollen-pistil interactions are an essential prelude to fertilization in angiosperms and determine compatibility/incompatibility. Pollen-pistil interactions have been studied at a molecular and cellular level in relatively few families. Self-incompatibility (SI) is the best understood pollen-pistil interaction at a molecular level where three different molecular mechanisms have been identified in just five families. Here we review studies of pollen-pistil interactions and SI in the Asteraceae, an important family that has been relatively understudied in these areas of reproductive biology. Scope We begin by describing the historical literature which first identified sporophytic SI (SSI) in species of Asteraceae, the SI system later identified and characterized at a molecular level in the Brassicaceae. Early structural and cytological studies in these two families suggested that pollen-pistil interactions and SSI were similar, if not the same. Recent cellular and molecular studies in Senecio squalidus (Oxford ragwort) have challenged this belief by revealing that despite sharing the same genetic system of SSI, the Brassicaceae and Asteraceae molecular mechanisms are different. Key cellular differences have also been highlighted in pollen-stigma interactions, which may arise as a consequence of the Asteraceae possessing a ‘semi-dry' stigma, rather than the ‘dry' stigma typical of the Brassicaceae. The review concludes with a summary of recent transcriptomic analyses aimed at identifying proteins regulating pollen-pistil interactions and SI in S. squalidus, and by implication the Asteraceae. The Senecio pistil transcriptome contains many novel pistil-specific genes, but also pistil-specific genes previously shown to play a role in pollen-pistil interactions in other species. Conclusions Studies in S. squalidus have shown that stigma structure and the molecular mechanism of SSI in the Asteraceae and Brassicaceae are different. The availability of a pool of pistil-specific genes for S. squalidus offers an opportunity to elucidate the molecular mechanisms of pollen-pistil interactions and SI in the Asteracea

Talking about human papillomavirus and cancer:development of consultation guides through lay and professional stakeholder coproduction using qualitative, quantitative and secondary data

Background High-risk human papillomaviruses (HPVs) cause all cervical cancer and the majority of vulvar, vaginal, anal, penile and oropharyngeal cancers. Although HPV is the most common sexually transmitted infection, public awareness of this is poor. In addition, many clinicians lack adequate knowledge or confidence to discuss sexual transmission and related sensitive issues. Complex science needs to be communicated in a clear, digestible, honest and salient way. Therefore, the aim of this study was to coproduce with patients who have cancer appropriate resources to guide these highly sensitive and difficult consultations. Methods A matrix of evidence developed from a variety of sources, including a systematic review and telephone interviews with clinicians, supported the production of a draft list of approximately 100 potential educational messages. These were refined in face-to-face patient interviews using card-sorting techniques, and tested in cognitive debrief interviews to produce a ‘fast and frugal’ knowledge tool. Results We developed three versions of a consultation guide, each comprising a clinician guidance sheet and patient information leaflet for gynaecological (cervical, vaginal, vulvar), anal or oropharyngeal cancers. That cancer could be caused by a sexually transmitted virus acquired many years previously was surprising to many and shocking to a few patients. However, they found the information clear, helpful and reassuring. Clinicians acknowledged a lack of confidence in explaining HPV, welcomed the clinician guidance sheets and considered printed information for patients particularly useful. Conclusion Because of the ‘shock factor’, clinicians will need to approach the discussion of HPV with sensitivity and take individual needs and preferences into account, but we provide a novel, rigorously developed and tested resource which should have broad applicability in the UK National Health Service and other health systems

Fivefold helically corrugated waveguide for high-power w-band gyro-devices and pulse compression

The design, simulation, manufacture and measurement of a W-band five-fold (5F) helically corrugated waveguide (HCW) is reported. The 5F HCW is based on the coupling of the traveling TE31 and near cut-off TE22 modes to create an operating eigenwave. The fabricated test structure has circular waveguide ports and features elliptical polariser sections and broadband TE11 to TE31 mode converters on either side of the 5F HCW. The optimised mode converter design, based on a four-fold (4F) HCW, has a predicted power conversion efficiency greater than 90% from 89 to 102.5 GHz, and 96% peak efficiency at 94 GHz. The optimization of the 5F HCW geometry produced an eigenwave suitable for gyro-devices, but the optimization could equally well have been directed to applications such as pulse compression and microwave undulators. Analysis of simulated electric field profiles showed that the propagating power in the 5F HCW was increased by a factor of 6 over that in the 3F HCW at equivalent peak electric field strength. This is due to the larger diameter of the waveguide. Test structures were manufactured through a combination of precision machining of a sacrificial mandrel, copper growth by electroforming followed by removal of the aluminium mandrel by chemically etching. Measurements of the 5F HCW structure’s dispersion showed excellent agreement with the prediction over the design range of 90 to 98 GHz

MASC 2022: What challenges and opportunities do supramolecular chemists face in coming years?

Supramolecular chemistry has gone from strength to strength in recent decades, with its impact felt from catalysis to materials science to chemical biology. This Voices article, published to coincide with the 2022 Macrocyclic and Supramolecular Chemistry Group meeting at the University of Nottingham, UK, asks speakers from the meeting: what are the major challenges and opportunities facing the field in coming years

A shared-care model of obesity treatment for 3-10 year old children: Protocol for the HopSCOTCH randomised trial

Extent: 17 p.BACKGROUND Despite record rates of childhood obesity, effective evidence-based treatments remain elusive. While prolonged tertiary specialist clinical input has some individual impact, these services are only available to very few children. Effective treatments that are easily accessible for all overweight and obese children in the community are urgently required. General practitioners are logical care providers for obese children but high-quality trials indicate that, even with substantial training and support, general practitioner care alone will not suffice to improve body mass index (BMI) trajectories. HopSCOTCH (the Shared Care Obesity Trial in Children) will determine whether a shared-care model, in which paediatric obesity specialists co-manage obesity with general practitioners, can improve adiposity in obese children. DESIGN Randomised controlled trial nested within a cross-sectional BMI survey conducted across 22 general practices in Melbourne, Australia. PARTICIPANTS Children aged 3–10 years identified as obese by Centers for Disease Control criteria at their family practice, and randomised to either a shared-care intervention or usual care. INTERVENTION A single multidisciplinary obesity clinic appointment at Melbourne’s Royal Children’s Hospital, followed by regular appointments with the child’s general practitioner over a 12 month period. To support both specialist and general practice consultations, web-based shared-care software was developed to record assessment, set goals and actions, provide information to caregivers, facilitate communication between the two professional groups, and jointly track progress. OUTCOMES Primary - change in BMI z-score. Secondary - change in percentage fat and waist circumference; health status, body satisfaction and global self-worth. DISCUSSION This will be the first efficacy trial of a general-practitioner based, shared-care model of childhood obesity management. If effective, it could greatly improve access to care for obese children. TRIAL REGISTRATION Australian New Zealand Clinical Trials Registry ACTRN12608000055303Melissa Wake, Kate Lycett, Matthew A Sabin, Jane Gunn, Kay Gibbons, Cathy Hutton, Zoe McCallum, Elissa York, Michael Stringer and Gary Witter

Genomic Clues to the Evolutionary Success of Polyploid Plants

Polyploidy, or the presence of two or more diploid parental genome sets within an organism, is found to an amazing degree in higher plants. In addition, many plant species traditionally considered to be diploid have recently been demonstrated to have undergone rounds of genome duplication in the past and are now referred to as paleopolyploids. Polyploidy and interspecific hybridisation (with which it is often associated) have long been thought to be important mechanisms of rapid species formation. The widespread occurrence of polyploids, which are frequently found in habitats different from that of their diploid progenitors, would seem to indicate that polyploidy is associated with evolutionary success in terms of the ability to colonise new environmental niches. A flurry of recent genomic studies has provided fresh insights into the potential basis of the phenotypic novelty of polyploid species. Here we review current knowledge of genetic, epigenetic, and transcriptional changes associated with polyploidy in plants and assess how these changes might contribute to the evolutionary success of polyploid plants. We conclude by stressing the need for field-based experiments to determine whether genetic changes associated with polyploidy are indeed adaptive