Antigen-Independent Maturation of CD2, CD11a/CD18, CD44, and CD58 Expression on Thymic Emigrants in Fetal and Postnatal Sheep

We have compared the expression of CD2, CD11a/CD18, CD44, and CD58 on αβ and γδ T cells emigrating from the fetal and postnatal thymus. We report that both γδ and the CD4+ CD8- and CD4-CD8+ subsets of αβ T cells express mature levels of the adhesion molecules CD11a/CD18, CD44, and CD58 upon emigration from the thymus. Whereas CD44 is up-regulated on γδ+ thymocytes prior to export, down-regulation of both CD11a/CD18 and CD58 occurs prior to emigration from the thymus, suggesting that down-regulation of these molecules may be a final maturational step taken by developing γδ T cells before their export from the thymus. In contrast, there is continued up-regulation of CD2 on αβ and γδ T cells upon emigration from the thymus and as they move into the mature peripheral T-cell pool. There was also a marked reduction in the number of CD2+ γδ T cells exported during fetal development that was associated with a marked reduction in the percentage of CD22+ γδ thymocytes exported. The postthymic maturation of CD2 and the other changes in adhesion-molecule expression appear to be independent of extrinsic antigen, as the same changes were observed in the antigen-free environment of the fetus as in the postnatal lamb, which has been exposed to extrinsic antigen. It thus appears that these changes in adhesion-molecule expression are as a result of the normal maturation pathway from a developing thymocyte to a mature peripheral T cell

Hydrogen reduction of ilmenite: Towards an in situ resource utilization demonstration on the surface of the Moon

Water is one of the most vital resources required for future space exploration. By obtaining water from lunar regolith, humans are one step closer to being independent of Earth's resources enabling longer term exploration missions. Hydrogen reduction of ilmenite is often proposed as a technique for producing water on the Moon. ProSPA, a miniature analytical laboratory, will perform reduction of lunar soils as an In-Situ Resource Utilization (ISRU) demonstration on the lunar surface. The technique used by ProSPA will be useful for prospecting payloads with limited mass and power resources. This work considers the development and optimization of an ilmenite (FeTiO3) reduction procedure for use with the ProSPA instrument. It is shown that the reaction can be performed in a static (non-flowing) system, by utilizing a cold finger to collect the water produced from the reaction. Among the investigated parameters an initial H2:FeTiO3 ratio of 1, in this case equating to a hydrogen pressure of 418 mbar, proved to be best for providing maximum yields over 4 h when operating at 1000 °C. Results indicate that a maximum yield of 3.40 ± 0.17 wt % O2 can be obtained at 1000 °C (with a maximum possible yield of 10.5 wt % O2). When operating at higher temperatures of 1100 °C the ilmenite grains undergo a subsolidus reaction resulting in the formation of ferropseudobrookite and higher yields of 4.42 ± 0.18 wt % O2 can be obtained

Feasibility studies for hydrogen reduction of ilmenite in a static system for use as an ISRU demonstration on the lunar surface

The ESA-ROSCOSMOS mission, Luna-27, scheduled for launch in 2023, includes a payload known as PROSPECT that is intended for sampling the polar lunar regolith through drilling, with subsequent analyses of the retrieved material. One of the aims of the analytical module, ProSPA, which is being developed at The Open University, is to identify and quantify the volatiles present in the extracted sample that are released by heating from ambient up to 1000 °C and analyzed by the mass spectrometers to assess their potential for in-situ resource utilization. The ProSPA design also includes a provision to test the extraction of water (and its associated oxygen) from lunar regolith by hydrogen reduction. Previous attempts at such extractions generally utilize a flow of hydrogen gas through the feedstock to efficiently extract water. However, in ProSPA, samples would be processed in a static mode, which leads to concerns that the reaction may be suppressed by inefficient removal of water vapor above the regolith. A first order theoretical assessment of the diffusion of gases in such a system was performed and suggested that water can diffuse through the system at an acceptable rate and be collected upon a cold finger thus enabling the reaction to proceed. Proof of concept experiments were successfully performed with a ProSPA breadboard using ilmenite samples up to ∼45 mg heated at 900 °C for 60 min. Subsequent heating of the cold finger, in vacuum, released 17 ± 1 μmol water from a 44.7 ± 0.5 mg sample, equating to a calculated yield of 0.6 ± 0.1 wt % oxygen, and a reduction extent of 5.8 ± 0.4%. A sample of mass 11.2 ± 0.5 mg had the greatest calculated yield of 1.4 ± 0.2 wt % oxygen, and this equates to a reduction extent of 12.9 ± 1.5%. SEM analyses of cross-sections of grains showed evidence of a reduction reaction inside the ilmenite grains with some showing greater reduction than others, indicating the reaction is limited by furnace dimensions, reaction kinetics and geometry. The results suggest that the ProSPA ISRU experiment should be capable of producing water, and therefore oxygen, by hydrogen reduction of ilmenite, ultimately this could be a viable technique for producing oxygen from ilmenite-containing lunar regolith with ProSPA

Mass Spectrometers for In-Situ Resource Utilisation

The Open University has a heritage in developing small mass spectrometers for planetary lander payloads. The first was a 6 cm radius magnetic sector instrument for light element isotopic analysis (H, C, N, and O), part of the Gas Analysis Package (GAP) on the Beagle 2 Mars lander. The second was the Ptolemy ion trap mass spectrometer (ITMS) on the Philae lander which successfully operated and returned results during the comet landing in November 2014. The Ptolemy ion trap unit fits within a 10 x 10 x 10 cm cube, including RF, detector and ion source electronics and is capable of a mass range from 10 to 150 amu at unit resolution. Development is continuing for purposes ranging from lander instruments (ProSPA and LUVMI), to rugged deployable probes (penetrators) and for process monitoring within ISRU plant. Many of the planned developments are aimed at the various stages of lunar ISRU, from resource prospecting to demonstration and optimisation of extraction processes

Developmental contexts and features of elite academy football players: Coach and player perspectives

Player profiling can reap many benefits; through reflective coach-athlete dialogue that produces a profile the athlete has a raised awareness of their own development, while the coach has an opportunity to understand the athlete's viewpoint. In this study, we explored how coaches and players perceived the development features of an elite academy footballer and the contexts in which these features are revealed, in order to develop a player profile to be used for mentoring players. Using a Delphi polling technique, coaches and players experienced a number of 'rounds' of expressing their opinions regarding player development contexts and features, ultimately reduced into a consensus. Players and coaches had differing priorities on the key contexts of player development. These contexts, when they reflect the consensus between players and coaches were heavily dominated by ability within the game and training. Personal, social, school, and lifestyle contexts featured less prominently. Although 'discipline' was frequently mentioned as an important player development feature, coaches and players disagreed on the importance of 'training'