A differential thermal analysis technique was used to study the carbothermic reduction of aluminum oxide a t reduced pressures in the temperature range 1700-2200" K. The reduction was found to proceed through the intermediate oxycarbide A1404C, identified by previous workers, to the aluminum carbide. The A140aC and another oxycarbide, AlZOC, were formed by a direct solid-solid reaction, rather than by formation of a gaseous aluminum suboxide and subsequent reaction with carbon as has been postulated.The carbon monoxide pressures over the following reactions were measured:Heats and free energies of reaction were found and standard heats and free energies of formation were calculated for AlzOC, A1404C, and A I L The values for A14C3 agreed with previously published results.The direct reaction did not occur. To account for the aluminum produced a t high temperatures, the reaction below was postulated:The calculated equilibrium pressure above this reaction agreed with experimental observations. ISTRODUCTIONIn the past few years, there has been a revival of interest in the production of aluminum by direct reduction (1, 2). Since a carbothermic reduction of aluminum oxide is involved in these processes, the present work was carried out to investigate the details of this reaction.Despite the industrial supremacy of the Hall-Heroult electrolytic process, there has been a sustained experimental interest in the aluminum-oxygen-carbon* system. Previous experiments on the system may be divided into two main groups. The first of these involved studies of the gas pressures existing above the system and paralleled the present investigation. The second, and more recent group, was a study of the compounds and phase relations occurring in the system, as determined by analyses of solidified melts of varying composition. In the latter group, a large number of compounds have been postulated by various workers (3, 4), but the existence of many of these has been disproved a t a later date. Foster, Long, and Hunter ( 5 ) have subjected the system to an extensive analysis in which two oxycarbides, AlpOC and A1404C, were found, as well as the known carbide,The existence of the two oxycarbides has been confirmed by Filonenko et al. (6, 7).* I n the text, the words graphite and carbon are used inte~changeably.

Personal contacts drive COVID-19 infections. After being closed (23 March 2020) UK primary schools partially re-opened on 1 June 2020 with social distancing and new risk mitigation strategies. We conducted a structured expert elicitation of teachers to quantify primary school contact patterns and how contact rates changed upon re-opening with risk mitigation measures in place. These rates, with uncertainties, were determined using a performance-based algorithm. We report mean number of contacts per day for four cohorts within schools, with associated 90% confidence ranges. Prior to lockdown, younger children (Reception and Year 1) made 15 contacts per day [range 8.35] within school, older children (Year 6) 18 contacts [range 5.55], teaching staff 25 contacts [range 4.55] and non-classroom staff 11 contacts [range 2.27]. After re-opening, the mean number of contacts was reduced by 53% for young children, 62% for older children, 60% for classroom staff and 64% for other staff. Contacts between teaching and non-teaching staff reduced by 80%. The distributions of contacts per person are asymmetric with heavy tail reflecting a few individuals with high contact numbers. Questions on risk mitigation and supplementary structured interviews elucidated how new measures reduced daily contacts in-school and contribute to infection risk reduction.

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Background Contact patterns are the drivers of close-contacts infections, such as COVID-19. In an effort to control COVID-19 transmission in the UK, schools were closed on 23 March 2020. With social distancing in place, Primary Schools were partially re-opened on 1 June 2020, with plans to fully re-open in September 2020. The impact of social distancing and risk mitigation measures on childrens contact patterns is not known. Methods We conducted a structured expert elicitation of a sample of Primary Headteachers to quantify contact patterns within schools in pre-COVID-19 times and how these patterns were expected to change upon re-opening. Point estimates with uncertainty were determined by a formal performance-based algorithm. Additionally, we surveyed school Headteachers about risk mitigation strategies and their anticipated effectiveness. Results Expert elicitation provides estimates of contact patterns that are consistent with contact surveys. We report mean number of contacts per day for four cohorts within schools along with a range at 90% confidence for the variations of contacts among individuals. Prior to lockdown, we estimate that, mean numbers per day, younger children (Reception and Year 1) made 15 contacts [range 8..35] within school, older children (Year 6) 18 contacts [range 5..55], teaching staff 25 contacts [range 4..55) and non-classroom staff 11 contacts [range 2..27]. Compared to pre-COVID times, after schools re-opened the mean number of contacts were reduced by about 53% for young children, about 62% for older children, about 60% for classroom staff and about 64% for other staff. Contacts between teaching and non-teaching staff reduced by 80%, which is consistent with other independent estimates. The distributions of contacts per person are asymmetric indicating a heavy tail of individuals with high contact numbers. Conclusions We interpret the reduction in childrens contacts as a consequence of efforts to reduce mixing with interventions such as forming groups of children (bubbles) who are organized to learn together to limit contacts. Distributions of contacts for children and adults can be used to inform COVID-19 transmission modelling. Our findings suggest that while official DfE guidelines form the basis for risk mitigation in schools, individual schools have adopted their own bespoke strategies, often going beyond the guidelines.

Prostaglandin E1 (PGE1) is currently being evaluated in clinical trials to determine its usefulness in the treatment of adult respiratory distress syndrome (ARDS). The drug is administered to ARDS patients by continuous intravenous infusion at dosage rates of up to 30 ng/kg/min for 7 days. The present study was conducted to determine the pulmonary extraction efficiency and pharmacokinetics of PGE1 under these conditions. Plasma levels of PGE1 were determined by high performance liquid chromatography in 14 patients who either had ARDS or were considered to be at risk of developing ARDS following trauma or sepsis. Predose plasma levels of PGE1 were below the detection limit of the assay (50 pg/ml). At a dosage rate of 30 ng/kg/min, pulmonary arterial and systemic arterial plasma levels ranged from 265 to 1,009 pg/ml and 50 to 796 pg/ml, respectively. The pulmonary extraction ratio (Ep) of PGE1 varied from 0.11 to 0.90 and was independent of dose but dependent on cardiac output. The data were adequately described by first-order pharmacokinetic equations which assumed that the lung was the only site of PGE1 clearance. Nine of 10 patients with AaPO2/FlO2 below 510 mm Hg had Ep greater than 0.7 and high pulmonary intrinsic clearance for PGE1 (ca. 250 L/min), but all 4 patients with AaPO2/FlO2 above 510 mm Hg had Ep less than 0.6 and low intrinsic clearance (ca. 37 L/min or less). The intrinsic clearance of the lung for PGE1 in ARDS patients therefore appears to decrease abruptly once a threshold of severe respiratory failure is achieved.