Design and implementation of a noise temperature measurement system for the Hydrogen Intensity and Real-time Analysis eXperiment (HIRAX)

This paper describes the design, implementation, and verification of a test-bed for determining the noise temperature of radio antennas operating between 400-800MHz. The requirements for this test-bed were driven by the HIRAX experiment, which uses antennas with embedded amplification, making system noise characterization difficult in the laboratory. The test-bed consists of two large cylindrical cavities, each containing radio-frequency (RF) absorber held at different temperatures (300K and 77K), allowing a measurement of system noise temperature through the well-known 'Y-factor' method. The apparatus has been constructed at Yale, and over the course of the past year has undergone detailed verification measurements. To date, three preliminary noise temperature measurement sets have been conducted using the system, putting us on track to make the first noise temperature measurements of the HIRAX feed and perform the first analysis of feed repeatability.Comment: 19 pages, 12 figure

Convalescent plasma in patients admitted to hospital with COVID-19 (RECOVERY): a randomised controlled, open-label, platform trial

Background: Many patients with COVID-19 have been treated with plasma containing anti-SARS-CoV-2 antibodies. We aimed to evaluate the safety and efficacy of convalescent plasma therapy in patients admitted to hospital with COVID-19. Methods: This randomised, controlled, open-label, platform trial (Randomised Evaluation of COVID-19 Therapy [RECOVERY]) is assessing several possible treatments in patients hospitalised with COVID-19 in the UK. The trial is underway at 177 NHS hospitals from across the UK. Eligible and consenting patients were randomly assigned (1:1) to receive either usual care alone (usual care group) or usual care plus high-titre convalescent plasma (convalescent plasma group). The primary outcome was 28-day mortality, analysed on an intention-to-treat basis. The trial is registered with ISRCTN, 50189673, and ClinicalTrials.gov, NCT04381936. Findings: Between May 28, 2020, and Jan 15, 2021, 11558 (71%) of 16287 patients enrolled in RECOVERY were eligible to receive convalescent plasma and were assigned to either the convalescent plasma group or the usual care group. There was no significant difference in 28-day mortality between the two groups: 1399 (24%) of 5795 patients in the convalescent plasma group and 1408 (24%) of 5763 patients in the usual care group died within 28 days (rate ratio 1·00, 95% CI 0·93–1·07; p=0·95). The 28-day mortality rate ratio was similar in all prespecified subgroups of patients, including in those patients without detectable SARS-CoV-2 antibodies at randomisation. Allocation to convalescent plasma had no significant effect on the proportion of patients discharged from hospital within 28 days (3832 [66%] patients in the convalescent plasma group vs 3822 [66%] patients in the usual care group; rate ratio 0·99, 95% CI 0·94–1·03; p=0·57). Among those not on invasive mechanical ventilation at randomisation, there was no significant difference in the proportion of patients meeting the composite endpoint of progression to invasive mechanical ventilation or death (1568 [29%] of 5493 patients in the convalescent plasma group vs 1568 [29%] of 5448 patients in the usual care group; rate ratio 0·99, 95% CI 0·93–1·05; p=0·79). Interpretation: In patients hospitalised with COVID-19, high-titre convalescent plasma did not improve survival or other prespecified clinical outcomes. Funding: UK Research and Innovation (Medical Research Council) and National Institute of Health Research

Characterisation of nickel(II) extraction by 2-hydroxy-5-nonylacetophenone oxime (LIX 84) in a micellar phase

The properties of the nickel(II)/2-hydroxy-5-nonylacetophenone oxime (HNAPO), an active ingredient in LIX 84, extraction system were characterised in a micellar system. The extinction coefficient, &lambda;max of HNAPO (316 nm) and the Ni2+ complex (387 nm) in a neutral micellar system, poly dispersed octa-ethyleneglycol mono-n-dodecyl ether (G12A8) were determined as 3100 and 3500 M&minus;1 cm&minus;1, respectively. HNAPO was found to have a neutral micellar phase and bulk aqueous phase pKa of 11.5 and 12.5, respectively. The extraction equilibrium constant, Kex, was determined to be 10&minus;8.0, and the deviation from theory observed at high pH can be accounted for by consideration of the competition for nickel(II) ions by hydroxide ions and HNAPO. A micellar phase of octa-ethyleneglycol mono-n-dodecyl ether (C12E8) was determined to be an appropriate model of the free oil/water interface from the solubilised location of HNAPO. Utilising the interfacial probe, 4-heptadecyl-7-hydroxy coumarin (HHC) allowed the determination of the electrostatic surface potential of mixed micelles of G12A8 and sodium dodecyl sulphate (SDS) or dodecyl trimethyl ammonium chloride (DTAC). The electrostatic surface potential was a linear function of the number of additional surfactant monomers within the G12A8 micelle, for the concentration range studied. For G12A8/DTAC mixed micelles, the surface potential was given by +1.1 mV per DTAC molecule per micelle, and for G12A8/SDS mixed micelles the relationship was &minus;1.4 mV per SDS molecule per micelle.<br /

Evaluation of the Structural Determinants of Polymeric Precipitation Inhibitors Using Solvent Shift Methods and Principle Component Analysis

The presence of polymers within solid dose forms, such as solid dispersions, or liquid or semisolid formulations, such as lipid-based formulations, can promote the maintenance of drug supersaturation after dissolution or dispersion/digestion of the vehicle in the gastrointestinal tract. Transiently stable supersaturation delays precipitation, increases thermodynamic activity, and may enhance bioavailability and reduce variability in exposure. In the current study a diverse range of 42 different classes of polymers, with a total of 78 polymers across all classes, grades, and molecular weights were examined, to varying degrees, as potential polymeric precipitation inhibitors (PPIs) using a solvent shift method to initiate supersaturation. To provide a deeper understanding of the molecular determinants of polymer utility the data were also analyzed, along with a range of physicochemical descriptors of the polymers employed, using principle component analysis (PCA). Polymers were selectively tested for their ability to stabilize supersaturation for nine poorly water-soluble model drugs, representing a range of nonelectrolytes, weak acids, and weak bases. In general, the cellulose-based polymers (and in particular hydroxypropylmethyl cellulose, HPMC, and its derivatives) provided robust precipitation inhibition across most of the drugs tested. Subsequent PCA indicate that there is consistent PPI behavior of a given polymer for a given drug type, with clear clustering of the performance of polymers with each of the nonelectrolytes, weak bases, and weak acids. However, there are some exceptions to this, with some specific drug type–polymer interactions also occurring. Polymers containing primary amine functional groups should be avoided as they are prone to enhancing precipitation rates. An inverse relationship was also documented for the number of amide, carboxylic acid, and hydroxyl functional groups; therefore for general good PPI performance the number of these contained within the polymer should be minimized. Molecular weight is a poor predictor of performance, having only a minor influence, and in some cases a higher molecular weight enhances the precipitation process. The importance of ionic interactions to the ability of a PPI to stabilize the supersaturated state was demonstrated by the advantage of choosing a polymer with an opposite charge with respect to the drug. Additionally, when the polymer charge is the same as the supersaturated drug, precipitation is likely to be enhanced. A PCA model based on polymer molecular properties is presented, which has a central oval region where the polymer will general perform well across all three drug types. If the polymer is located outside of this region, then they either show compound-specific inhibition or enhance precipitation. Incomplete separation of the PPI performance based on the molecular properties on the polymers indicates that there are some further molecular properties that might improve the correlation