From mantle to critical zone : a review of large and giant sized deposits of the rare earth elements

MS, AF and FW acknowledge the support of the NERC SoS:RARE consortium grant (NE/M011267/1). D. Kavecsanszki acknowledges the support of a postgraduate fellowship from the College of Engineering, Mathematics and Physical Sciences at the University of Exeter.The rare earth elements are unusual when defining giant-sized ore deposits, as resources are often quoted as total rare earth oxide, but the importance of a deposit may be related to the grade for individual, or a limited group of, the elements. Taking the total REE resource, only one currently known deposit (Bayan Obo) would class as giant (>1.7×107 tonnes contained metal), but a range of others classify as large (>1.7×106 tonnes). With the exception of unclassified resource estimates from the Olympic Dam IOCG deposit, all of these deposits are related to alkaline igneous activity – either carbonatites or agpaitic nepheline syenites. The total resource in these deposits must relate to the scale of the primary igneous source, but the grade is a complex function of igneous source, magmatic crystallisation, hydrothermal modification and supergene enrichment during weathering. Isotopic data suggest that the sources conducive to the formation of large REE deposits are developed in subcontinental lithospheric mantle, enriched in trace elements either by plume activity, or by previous subduction. The reactivation of such enriched mantle domains in relatively restricted geographical areas may have played a role in the formation of some of the largest deposits (e.g. Bayan Obo). Hydrothermal activity involving fluids from magmatic to meteoric sources may result in the redistribution of the REE and increases in grade, depending on primary mineralogy and the availability of ligands. Weathering and supergene enrichment of carbonatite has played a role in the formation of the highest grade deposits at Mount Weld (Australia) and Tomtor (Russia). For the individual REE with the current highest economic value (Nd and the HREE), the boundaries for the large and giant size classes are 2 orders of magnitude lower, and deposits enriched in these metals (agpaitic systems, ion absorption deposits) may have significant economic impact in the near future.Publisher PDFPeer reviewe

Structure and magnetic properties of the cubic oxide fluoride BaFeO2F

Fluorination of the parent oxide, BaFeO3- δ, with polyvinylidine fluoride gives rise to a cubic compound with a = 4.0603(4) Å at 298K. 57Fe Mössbauer spectra confirmed that all the iron is present as Fe3+. Neutron diffraction data showed complete occupancy of the anion sites indicating a composition BaFeO2F, with a large displacement of the iron off-site. The magnetic ordering temperature was determined as TN = 645±5K. Neutron diffraction data at 4.2K established G-type antiferromagnetism with a magnetic moment per Fe3+ ion of 3.95μB. However, magnetisation measurements indicated the presence of a weak ferromagnetic moment which is assigned to the canting of the antiferromagnetic structure. 57Fe Mössbauer spectra in the temperature range 10 to 300K were fitted with a model of fluoride ion distribution that retains charge neutrality of the perovskite unit cel

Experimentally integrated dynamic modelling for intuitive optimisation of cell based processes and manufacture

Dynamic mechanistic modelling of cell culture is a key tool in bioprocess development to support optimisation and risk assessment. However, the approach is underutilised in the bioprocess industry due to challenges including lack of accessible tools to support a structured approach, the difficulty of realising computationally tractable (low parameter) yet realistic models, and the specialised skill sets required. We have proposed that these issues could be partly addressed by developing a parsimonious framework comprising a set of model building blocks, based on the ordinary differential equation modelling paradigm, representing common cell culture dynamics and modulation thereof. The framework is designed to avoid obvious pathological behaviours. Further, specific model instances within the framework can be simply visualised as a directed graph with vertices representing system species, dynamics and modulations, and arcs representing the interactions between them. The directed graph can be extended to describe the timing and nature of experimental interventions. A visual and intuitive route to describing models with an associated mathematical framework enables realisation in a software interface and integration with standard mathematical tools such as those for sensitivity analysis and parameter estimation. Such a framework is sufficient to represent some of the simple mechanisms underpinning bioprocesses that nonetheless lead to highly non-linear and counterintuitive outcomes. It also has a relatively low learning burden for users without formal mathematical training. The concept could be extended to include, for example, partial differential equation-based approaches to stochastic or spatially complex systems built up from a small number of parametrically parsimonious and well-behaved building blocks

The influence of self-talk on challenge and threat states and performance

Objectives A psychophysiological response called a challenge state has been associated with better performance than a threat state. However, to date, challenge-promoting interventions have rarely been tested. Therefore, this study investigated whether instructional and/or motivational self-talk promoted a challenge state and improved task performance. Design A three-group, randomised-controlled experimental design was used. Method Sixty-two participants (52 males, 10 females; Mage = 24 years, SD = 6) were randomly assigned to one of three self-talk groups: instructional, motivational, or control (verbalising trial number). Participants performed four dart-throwing tasks. Cognitive and cardiovascular measures of challenge and threat states were recorded before the first and final task. Results The motivational, but not the instructional group, improved their performance between the first and final tasks more than the control group. Self-talk had no effect on the cognitive or cardiovascular challenge and threat measures. However, evaluating the task as more of a challenge (coping resources match/exceed task demands) was related to better performance. Cardiovascular reactivity more reflective of a challenge state (higher cardiac output and/or lower total peripheral resistance reactivity) was more positively related to performance in the motivational than in the control group, and in the control than the instructional group. Conclusions Motivational self-talk improved performance more than control self-talk. Furthermore, motivational self-talk may have strengthened, whereas instructional self-talk may have weakened, the relationship between challenge and threat states and performance. Hence, athletes in a challenge state may benefit from motivational self-talk, whereas those in a threat state may profit from instructional self-talk

Application of quality by design tools to upstream processing of platelet precursor cells to enable in vitro manufacture of blood products

Annually 4.5 million platelet units are transfused in Europe and the United States. These are obtained solely from allogeneic donations and have a shelf life of 5-7 days. To address the corresponding supply challenge, Moreau et al.1 devised a novel process for producing megakaryocytes (MKs, the platelet precursor cell) in vitro. A transcription-factor driven, forward-programming (FOP) approach converts human pluripotent stem cells into MKs. This strategy has the unique advantage of generating high yields of pure MKs in chemically defined medium which could lead to the production of a consistent, reliable supply of platelets which overcomes the logistical, financial and biosafety challenges for health organisations worldwide. Here we follow a Quality by Design (QbD) approach to enable improvements to the upstream processing of FOPMKs. Firstly, we created a process flow diagram for production of in vitro platelets for transfusion, which segregated processes into individual unit operations for control and optimisation. Next, we developed a Quality Target Product Profile (QTPP) and identified Critical Quality Attributes (CQAs) for each stage. We conducted a range of experiments utilising Design of Experiments (DOE) and mechanistic modelling2 tools to link Critical Process Parameters (CPPs) to CQAs. For adherent culture, we identified a productivity limit related to surface area available for growth and a cell loss phase which was dependent on cell seeding density, RhoK inhibitor usage and seed density. Using suspension cultures of FOPMK. We noted that TPO and Doxycycline concentration were CPPs as these impacted cell net growth rate and phenotype trajectory. Furthermore, we noted that medium exhaustion led to a 30% loss of viable cells over 8 hours. Proof of concept studies also showed that FOPMKs can be cultured in scaled-down suspension systems (ambr-15 and spinner flask culture) whilst retaining CQAs. 1. Moreau, T. et al. Large-scale production of megakaryocytes from human pluripotent stem cells by chemically defined forward programming. Nat. Commun. 7, 1–15 (2016). 2. Stacey, A. J., Cheeseman, E. A., Glen, K. E., Moore, R. L. L. & Thomas, R. J. Experimentally integrated dynamic modelling for intuitive optimisation of cell-based processes and manufacture. Biochem. Eng. J. 132, 130–138 (2018)

Ozone loss derived from balloon-borne tracer measurements and the SLIMCAT CTM

Balloon-borne measurements of CFC-11 (on flights of the DIRAC in situ gas chromatograph and the DESCARTES grab sampler), ClO and O3 were made during the 1999/2000 winter as part of the SOLVE-THESEO 2000 campaign. Here we present the CFC-11 data from nine flights and compare them first with data from other instruments which flew during the campaign and then with the vertical distributions calculated by the SLIMCAT 3-D CTM. We calculate ozone loss inside the Arctic vortex between late January and early March using the relation between CFC-11 and O3 measured on the flights, the peak ozone loss (1200 ppbv) occurs in the 440–470 K region in early March in reasonable agreement with other published empirical estimates. There is also a good agreement between ozone losses derived from three independent balloon tracer data sets used here. The magnitude and vertical distribution of the loss derived from the measurements is in good agreement with the loss calculated from SLIMCAT over Kiruna for the same days

Association of dietary flavan-3-ol intakes with plasma phenyl-γ-valerolactones: analysis from the TUDA cohort of healthy older adults

Background: Dietary polyphenols, including flavan-3-ols (F3O), are associated with better health outcomes. The relationship of plasma phenyl-γ-valerolactones (PVLs), the products of colonic bacterial metabolism of F3O, with dietary intakes is unclear. Objectives: To investigate whether plasma PVLs are associated with self-reported intakes of total F3O and procyanidins+(epi)catechins. Design: We measured 9 PVLs by uHPLC-MS-MS in plasma from adults (>60y) in the Trinity-Ulster-Department of Agriculture (TUD study (2008 to 2012; n=5,186) and a follow-up subset (2014 to 2018) with corresponding dietary data (n=557). Dietary (poly)phenols collected by FFQ were analyzed using Phenol-Explorer. Results: Mean (95% confidence interval [CI]) intakes were estimated as 2283 (2213, 2352) mg/d for total (poly)phenols, 674 (648, 701) for total F3O, and 152 (146, 158) for procyanidins+(epi)catechins. Two PVL metabolites were detected in plasma from the majority of participants, 5-(hydroxyphenyl)-γ-VL-sulfate (PVL1) and 5-(4'-hydroxyphenyl)-γ-VL-3'-glucuronide (PVL2). The 7 other PVLs were detectable only in 1-32% of samples. Self-reported intakes (mg/d) of F3O (r = 0.113, P = 0.017) and procyanidin+(epi)catechin (r = 0.122, P = 0.010) showed statistically significant correlations with the sum of PVL1 and PVL 2 (PVL1+2). With increasing intake quartiles (Q1-Q4), mean (95% CI) PVL1+2 increased; from 28.3 (20.8, 35.9) nmol/L in Q1 to 45.2 (37.2, 53.2) nmol/L in Q4; P = 0.025, for dietary F3O, and from 27.4 (19.1, 35.8) nmol/L in Q1 to 46.5 (38.2, 54.9) nmol/L in Q4; P = 0.020, for procyanidins+(epi)catechins. Conclusions: Of 9 PVL metabolites investigated, 2 were detected in most samples and were weakly associated with intakes of total F3O and procyanidins+(epi)catechins. Future controlled feeding studies are required to validate plasma PVLs as biomarkers of these dietary polyphenols