First-principles thermodynamic modeling of lanthanum chromate perovskites

Tendencies toward local atomic ordering in (A,A′)(B,B′)O_(3−δ) mixed composition perovskites are modeled to explore their influence on thermodynamic, transport, and electronic properties. In particular, dopants and defects within lanthanum chromate perovskites are studied under various simulated redox environments. (La_(1−x),Sr_x)(Cr_(1−y),Fe_y)O_(3−δ) (LSCF) and (La_(1−x),Sr_x)(Cr_(1−y),Ru_y)O_(3−δ) (LSCR) are modeled using a cluster expansion statistical thermodynamics method built upon a density functional theory database of structural energies. The cluster expansions are utilized in lattice Monte Carlo simulations to compute the ordering of Sr and Fe(Ru) dopant and oxygen vacancies (Vac). Reduction processes are modeled via the introduction of oxygen vacancies, effectively forcing excess electronic charge onto remaining atoms. LSCR shows increasingly extended Ru-Vac associates and short-range Ru-Ru and Ru-Vac interactions upon reduction; LSCF shows long-range Fe-Fe and Fe-Vac interaction ordering, inhibiting mobility. First principles density functional calculations suggest that Ru-Vac associates significantly decrease the activation energy of Ru-Cr swaps in reduced LSCR. These results are discussed in view of experimentally observed extrusion of metallic Ru from LSCR nanoparticles under reducing conditions at elevated temperature

First-principles thermodynamic modeling of atomic ordering in yttria-stabilized zirconia

Yttria-stabilized zirconia YSZ is modeled using a cluster expansion statistical thermodynamics method built upon a density-functional theory database. The reliability of cluster expansions in predicting atomic ordering is explored by comparing with the extensive experimental database. The cluster expansion of YSZ is utilized in lattice Monte Carlo simulations to compute the ordering of dopant and oxygen vacancies as a function of concentration. Cation dopants show a strong tendency to aggregate and vacate significantly sized domains below 9 mol % Y_2O_3, which is likely important for YSZ aging processes in ionic conductivity. Evolution of vibrational and underlying electronic properties as a function of Y doping is explored

An epigenetic clock for gestational age at birth based on blood methylation data

Background: Gestational age is often used as a proxy for developmental maturity by clinicians and researchers alike. DNA methylation has previously been shown to be associated with age and has been used to accurately estimate chronological age in children and adults. In the current study, we examine whether DNA methylation in cord blood can be used to estimate gestational age at birth. Results: We find that gestational age can be accurately estimated from DNA methylation of neonatal cord blood and blood spot samples. We calculate a DNA methylation gestational age using 148 CpG sites selected through elastic net regression in six training datasets. We evaluate predictive accuracy in nine testing datasets and find that the accuracy of the DNA methylation gestational age is consistent with that of gestational age estimates based on established methods, such as ultrasound. We also find that an increased DNA methylation gestational age relative to clinical gestational age is associated with birthweight independent of gestational age, sex, and ancestry. Conclusions: DNA methylation can be used to accurately estimate gestational age at or near birth and may provide additional information relevant to developmental stage. Further studies of this predictor are warranted to determine its utility in clinical settings and for research purposes. When clinical estimates are available this measure may increase accuracy in the testing of hypotheses related to developmental age and other early life circumstances

This is my boy’s health! Talk straight to me! perspectives on accessible and culturally safe care among Aboriginal and Torres Strait Islander patients of clinical genetics services

Abstract Background Aboriginal and Torres Strait Islander people do not enjoy equal access to specialist health services that adequately meet their needs. Clinical genetics services are at the vanguard of realising the health benefits of genomic medicine. As the field continues to expand in clinical utility and implementation, it is critical that Aboriginal and Torres Strait Islander people are able to participate and benefit equally to avoid further widening of the existing health gap. This is the first study to explore barriers to accessing clinical genetics services among Aboriginal and Torres Strait Islander people, which has been acknowledged as a key strategic priority in Australian genomic health policy. Methods A participatory design process engaged a majority-Aboriginal Project Reference Group and Aboriginal End-User Group. 63 semi-structured interviews were conducted with Aboriginal and/or Torres Strait Islander people who had accessed the government-funded clinical genetics service in Western Australia, Queensland or the Northern Territory between 2014 and 2018. The sample included patients, parents and carers. Participants were asked to recount their &lsquo;patient journey&rsquo;, from referral through to post-appointment and reflect on their perceptions of genetics and its implications for the health of themselves and their families. Analysis tracked chronological service engagement, followed by an inductive thematic approach. Results Barriers to access and engagement were present at each stage of the patient journey. These included challenges in obtaining a referral, long waiting periods, limited genetic literacy, absence of Aboriginal support services, communication challenges and lack of adequate psychosocial support and follow-up after attendance. Participants&rsquo; overall experiences of attending a genetic health service were varied, with positive perceptions tied closely to a diagnosis being achieved. The experience of (and expectation for) recognition of cultural identity and provision of culturally safe care was low among participants. Unaddressed concerns continued to cause significant distress in some people years after their appointment took place. Conclusions There is significant scope for improving the care provided to Aboriginal and Torres Strait Islander people at clinical genetics services. Immediate attention to minimising logistical barriers, developing relationships with Aboriginal Community Controlled Health Services and providing practical and specific cultural safety training for practitioners is required at the service-level. Our findings strongly support the development of guidelines or policies recognising the collective cultural needs of Aboriginal and Torres Strait Islander people in relation to genomic health care. </jats:sec