Aluminium-26 production in low- and intermediate-mass binary systems

Aluminium-26 is a radioactive isotope which can be synthesized within asymptotic giant branch (AGB) stars, primarily through hot bottom burning. Studies exploring $^{26}$Al production within AGB stars typically focus on single-stars; however, observations show that low- and intermediate-mass stars commonly exist in binaries. We use the binary population synthesis code binary_c to explore the impact of binary evolution on $^{26}$Al yields at solar metallicity both within individual AGB stars and a low/intermediate-mass stellar population. We find the key stellar structural condition achieving most $^{26}$Al overproduction is for stars to enter the thermally-pulsing AGB (TP-AGB) phase with small cores relative to their total masses, allowing those stars to spend abnormally long times on the TP-AGB compared to single-stars of identical mass. Our population with a binary fraction of 0.75 has an $^{26}$Al weighted population yield increase of $25\%$ compared to our population of only single-stars. Stellar-models calculated from the Mt Stromlo/Monash Stellar Structure Program, which we use to test our results from binary_c and closely examine the interior structure of the overproducing stars, support our binary_c results only when the stellar envelope gains mass after core-He depletion. Stars which gain mass before core-He depletion still overproduce $^{26}$Al, but to a lesser extent. This introduces some physical uncertainty into our conclusions as $55\%$ of our $^{26}$Al overproducing stars gain envelope mass through stellar wind accretion onto pre-AGB objects. Our work highlights the need to consider binary influence on the production of $^{26}$Al.Comment: 20 pages, 17 figures, and 6 tables. This article has been accepted for publication in MNRAS Published by Oxford University Press on behalf of the Royal Astronomical Societ

Viability of novae as sources of Galactic lithium

Of all the light elements, the evolution of lithium (Li) in the Milky Way is perhaps the most difficult to explain. Li is difficult to synthesize and is easily destroyed, making most stellar sites unsuitable for producing Li in sufficient quantities to account for the proto-solar abundance. For decades, novae have been proposed as a potential explanation to this 'Galactic Li problem', and the recent detection of 7Be in the ejecta of multiple nova eruptions has breathed new life into this theory. In this work, we assess the viability of novae as dominant producers of Li in the Milky Way. We present the most comprehensive treatment of novae in a galactic chemical evolution code to date, testing theoretical- and observationally-derived nova Li yields by integrating metallicity-dependent nova ejecta profiles computed using the binary population synthesis code binary c with the galactic chemical evolution code OMEGA+. We find that our galactic chemical evolution models which use observationally-derived Li yields account for the proto-solar Li abundance very well, while models relying on theoretical nova yields cannot reproduce the proto-solar observation. A brief exploration of physical uncertainties including single-stellar yields, the metallicity resolution of our nova treatment, common-envelope physics, and nova accretion efficiencies indicates that this result is robust to physical assumptions. Scatter within the observationally-derived Li yields in novae is identified as the primary source of uncertainty, motivating further observations of 7Be in nova ejecta.Comment: Accepted for publication in ApJL 28/7/202

A novel approach to oral iron delivery using ferrous sulphate loaded solid lipid nanoparticles

Iron (Fe) loaded solid lipid nanoparticles (SLN’s) were formulated using stearic acid and iron absorp-tion was evaluated in vitro using the cell line Caco-2 with intracellular ferritin formation as a marker ofiron absorption. Iron loading was optimised at 1% Fe (w/w) lipid since an inverse relation was observedbetween initial iron concentration and SLN iron incorporation efficiency. Chitosan (Chi) was included toprepare chitosan coated SLN’s. Particle size analysis revealed a sub-micron size range (300.3 ± 31.75 nmto 495.1 ± 80.42 nm), with chitosan containing particles having the largest dimensions. As expected,chitosan (0.1%, 0.2% and 0.4% w/v) conferred a net positive charge on the particle surface in a concen-tration dependent manner. For iron absorption experiments equal doses of Fe (20 �M) from selectedformulations (SLN-FeA and SLN-Fe-ChiB) were added to Caco-2 cells and intracellular ferritin proteinconcentrations determined. Caco-2 iron absorption from SLN-FeA (583.98 ± 40.83 ng/mg cell protein)and chitosan containing SLN-Fe-ChiB (642.77 ± 29.37 ng/mg cell protein) were 13.42% and 24.9% greaterthan that from ferrous sulphate (FeSO4) reference (514.66 ± 20.43 ng/mg cell protein) (p ≤ 0.05). Wedemonstrate for the first time preparation, characterisation and superior iron absorption in vitro fromSLN’s, suggesting the potential of these formulations as a novel system for oral iron delivery

Genital tract inflammation during early HIV-infection predicts higher plasma viral load set point in women.

Background. The biggest challenge in human immunodeficiency virus type 1 (HIV-1) prevention in Africa is the high HIV-1 burden in young women. In macaques, proinflammatory cytokine production in the genital tract is necessary for target cell recruitment and establishment of simian immunodeficiency virus (SIV) infection following vaginal inoculation. The purpose of this study was to assess if genital inflammation during early HIV-1 infection predisposes women to rapid disease progression. Methods. Inflammatory cytokine concentrations were measured in cervicovaginal lavage (CVL) from 49 women 6, 17, 30, and 55 weeks after HIV-1 infection and from 22 of these women before infection. Associations between genital inflammation and viral load set point and blood CD4 cell counts 12 months after infection were investigated. Results. Elevated genital cytokine concentrations 6 and 17 weeks after HIV-1 infection were associated with higher viral load set points and, to a lesser extent, with CD4 depletion. CVL cytokine concentrations during early infection did not differ relative to preinfection but were elevated in women who had vaginal discharge, detectable HIV-1 RNA in their genital tracts, and lower blood CD4 counts. Conclusion. Genital inflammation during early HIV-1 infection was associated with higher viral load set point and CD4 depletion, which are markers of rapid disease progression. Strategies aimed at reducing genital inflammation during early HIV-1 infection may slow disease progression

The Cambridge Study: Previous Results

The Cambridge Study in Delinquent Development represents one of the longest and most comprehensive, prospective longitudinal studies in the world focusing on offending, risk factors, and life events. Evidence gleaned from nearly five decades of research has generated a wealth of empirical information relevant for criminology and related disciplines with regard to family criminality, the relationship between employment and crime, risk factors associated with offending, the association between offending and adverse physical health outcomes, and the costs of crime. This chapter reviews these research findings in detail and concludes with a discussion of the strengths and limitations of the Cambridge Study in Delinquent Development

Author Correction: The messy death of a multiple star system and the resulting planetary nebula as observed by JWST

International audienc

The messy death of a multiple star system and the resulting planetary nebula as observed by JWST

International audiencePlanetary nebulae—the ejected envelopes of red giant stars—provide us with a history of the last, mass-losing phases of 90% of stars initially more massive than the Sun. Here we analyse images of the planetary nebula NGC 3132 from the James Webb Space Telescope (JWST) Early Release Observations. A structured, extended hydrogen halo surrounding an ionized central bubble is imprinted with spiral structures, probably shaped by a low-mass companion orbiting the central star at about 40-60 au. The images also reveal a mid-infrared excess at the central star, interpreted as a dusty disk, which is indicative of an interaction with another closer companion. Including the previously known A-type visual companion, the progenitor of the NGC 3132 planetary nebula must have been at least a stellar quartet. The JWST images allow us to generate a model of the illumination, ionization and hydrodynamics of the molecular halo, demonstrating the power of JWST to investigate complex stellar outflows. Furthermore, new measurements of the A-type visual companion allow us to derive the value for the mass of the progenitor of a central star with excellent precision: 2.86 ± 0.06 M⊙. These results serve as pathfinders for future JWST observations of planetary nebulae, providing unique insight into fundamental astrophysical processes including colliding winds and binary star interactions, with implications for supernovae and gravitational-wave systems