A compact instrument for gamma-ray burst detection on a CubeSat platform II: Detailed design, assembly and validation.

The Gamma-ray Module, GMOD, is a miniaturised novel gamma-ray detector which will be the primary scientific payload on the Educational Irish Research Satellite (EIRSAT-1) 2U CubeSat mission. GMOD comprises a compact (25 mm × 25 mm × 40 mm) cerium bromide scintillator coupled to a tiled array of 4 × 4 silicon photomultipliers, with front-end readout provided by the IDE3380 SIPHRA. This paper presents the detailed GMOD design and the accommodation of the instrument within the restrictive CubeSat form factor. The electronic and mechanical interfaces are compatible with many off-the-shelf CubeSat systems and structures. The energy response of the GMOD engineering qualification model has been determined using radioactive sources, and an energy resolution of 5.4% at 662 keV has been measured. EIRSAT-1 will perform on-board processing of GMOD data. Trigger results, including light-curves and spectra, will be incorporated into the spacecraft beacon and transmitted continuously. Inexpensive hardware can be used to decode the beacon signal, making the data accessible to a wide community. GMOD will have scientific capability for the detection of gamma-ray bursts, in addition to the educational and technology demonstration goals of the EIRSAT-1 mission. The detailed design and measurements to date demonstrate the capability of GMOD in low Earth orbit, the scalability of the design for larger CubeSats and as an element of future large gamma-ray missions.

Balloon flight test of a CeBr3 detector with silicon photomultiplier readout.

Recent advances in silicon photomultiplier (SiPM) technology and new scintillator materials allow for the creation of compact high-performance gamma-ray detectors which can be deployed on small low-cost satellites. A small number of such satellites can provide full sky coverage and complement, or in some cases replace the existing gamma-ray missions in detection of transient gamma-ray events. The aim of this study is to test gamma-ray detection using a novel commercially available CeBr3 scintillator combined with SiPM readout in a near-space environment and inform further technology development for a future space mission. A prototype gamma-ray detector was built using a CeBr3 scintillator and an array of 16 J-Series SiPMs by ON Semiconductor. SiPM readout was performed using SIPHRA, a radiation-tolerant low-power integrated circuit developed by IDEAS. The detector was flown as a piggyback payload on the Advanced Scintillator Compton Telescope balloon flight from Columbia Scientific Balloon Facility. The payload included the detector, a Raspberry Pi on-board computer, a custom power supply board, temperature and pressure sensors, a Global Navigation Satellite System receiver and a satellite modem. The balloon delivered the detector to 37 km altitude where its detection capabilities and readout were tested in the radiation-intense near-space environment. The detector demonstrated continuous operation during the 8-hour flight and after the landing. It performed spectral measurements in an energy range of 100 keV to 8 MeV and observed the 511 keV gamma-ray line arising from positron annihilation in the atmosphere with full width half maximum of 6.8%. During ascent and descent, the detector count rate peaked at an altitude of 16 km corresponding to the point of maximum radiation intensity in the atmosphere. Despite several engineering issues discovered after the flight test, the results of this study confirm the feasibility of using CeBr3 scintillator, SiPMs, and SIPHRA in future space missions.

A compact instrument for gamma-ray burst detection on a CubeSat platform I: Design drivers and expected performance.

The Educational Irish Research Satellite 1 (EIRSAT-1) is a 2U CubeSat being developed under ESA's Fly Your Satellite! programme. The project has many aspects, which are primarily educational, but also include space qualification of new detector technologies for gamma-ray astronomy and the detection of gamma-ray bursts (GRBs). The Gamma-ray Module (GMOD), the main mission payload, is a small gamma-ray spectrometer comprising a 25 mm × 25 mm × 40 mm cerium bromide scintillator coupled to an array of 16 silicon photomultipliers. The readout is provided by IDE3380 (SIPHRA), a low-power and radiation tolerant readout ASIC. GMOD will detect gamma-rays and measure their energies in a range from tens of keV to a few MeV. Monte Carlo simulations were performed using the Medium Energy Gamma-ray Astronomy Library to evaluate GMOD's capability for the detection of GRBs in low Earth orbit. The simulations used a detailed mass model of the full spacecraft derived from a very high-fidelity 3D CAD model. The sky-average effective area of GMOD on board EIRSAT-1 was found to be 10 cm2 at 120 keV. The instrument is expected to detect between 11 and 14 GRBs, at a significance greater than 10σ (and up to 32 at 5σ), during a nominal one-year mission. The shape of the scintillator in GMOD results in omni-directional sensitivity which allows for a nearly all-sky field of view.

Preparative purification of recombinant proteins: current status and future trends.

Advances in fermentation technologies have resulted in the production of increased yields of proteins of economic, biopharmaceutical, and medicinal importance. Consequently, there is an absolute requirement for the development of rapid, cost-effective methodologies which facilitate the purification of such products in the absence of contaminants, such as superfluous proteins and endotoxins. Here, we provide a comprehensive overview of a selection of key purification methodologies currently being applied in both academic and industrial settings and discuss how innovative and effective protocols such as aqueous two-phase partitioning, membrane chromatography, and high-performance tangential flow filtration may be applied independently of or in conjunction with more traditional protocols for downstream processing applications.

Determination of calcium in synovial fluid samples as an aid to diagnosing osteoarthritis.

BACKGROUND: Microscopic inorganic crystals are commonly observed in the synovial fluid of patients suffering from arthritic diseases. Basic calcium phosphate (BCP) crystals are known to occur quite commonly in the joint fluid of osteoarthritis (OA) patients and are insoluble at physiological pH. Current analysis of patient synovial fluid depends on light microscopy and staining with Alizarin Red-S. Both methods cannot identify crystals < 1µm in size and are highly subjective. This article investigates the use of o-cresolphthalein complexone (OCP), a colorimetric reagent, to quantify calcium from crystals isolated from synovial fluid samples as a means of identifying the presence of BCP and, hence, improving the diagnosis of OA. RESULTS: Inorganic crystals were isolated following degradation of the biological sample matrix with hyaluronidase. 1-M HNO(3) was used for crystal dissociation into ions and the colorimetric response of OCP to calcium was measured in a basic environment of 2-amino-2-methyl-1-propanol. The average calcium content in OA patient samples was up to 40% higher than in rheumatoid arthritis (RA) patient samples. RA samples were used as a comparison, because they are generally accepted to be crystal free. Within the OA group, higher levels of calcium were detected in three out of 12 synovial fluid samples, which correlated with a significantly greater number of BCP crystals detected during microscopic examination. CONCLUSIONS: A simple method based on colorimetry for measurement of calcium content and semiquantification of BCP crystals in synovial fluid samples has been described. Sample pretreatment following addition of hyaluronidase proved to be effective in reducing viscosity and aiding the dissociation of BCP crystals in synovial fluid samples.