Optimization of cyclotron production for radiometal of Zirconium 89

Zirconium 89 (89Zr) is a promising radionuclide for development of new PET agents due to its convenient half life of 78.4 h, β+ emission rate of 23%, low maximum energy of 0.9 MeV resulting in good spatial resolution, a stable daughter isotope of yttrium-89 (89Y) and favorable imaging characteristics, with only one significant γ-line of 909 keV emitted during decay alongside the 511 keV positron photons. Our aim was to share over 2 years of experience of producing isotopically pure 89Zr via the 89Y(p,n)89Zr nuclear reaction with a COSTIS Solid Target System (STS) and CYCLONE 18/9 cyclotron. We optimized the yields without producing either of the long-lived impurities 88Zr or 88Y. The degradation of the beam energy with 400 and 500 μm thick niobium foils was tested without overheating problems within 2-6 h of irradiation. From repeated measurements of activity, it was clear that there is a bi-exponential decay of radioactivity due to the short lived 89mZr and 89Zr. The measured half life of the longer lived radionuclide was consistent with value for 89Zr. The energy spectrum from 89Zr had energy peaks at 511 keV and 909 keV and was consistent with 89Zr. Production of 89Zr with 400 (Ep = 9.8 MeV) and 500 μ m (Ep = 11.6 MeV) thick niobium beam degrader was achieved, without producing either 88Zr or 88Y. It was necessary to wait at least 4 hours before measuring the activity and decay correct in order to calculate the 89Zr activity at the end of cyclotron production. Degrading the proton beam to 10 MeV produces radionuclidically pure 89Zr with yields from 8 to 9 MBq/μAh. Whilst this is enough for pre-clinical use, the yield is not enough for either clinical use or commercial supply. Use of thinner beam degraders (400 μm) increases the proton beam energy and increases the radionuclidic yield to 15.5 MBq/μAh whilst maintaining radionuclidic purity

Flow turning effect and laminar control by the 3D curvature of leading edge serrations from owl wing

This work describes a novel mechanism of laminar flow control of a backward swept wing with a comb-like leading edge device. It is inspired by the leading-edge comb on owl feathers and the special design of its barbs, resembling a cascade of complex 3D-curved thin finlets. The details of the geometry of the barbs from an owl feather were used to design a generic model of the comb for experimental and numerical flow studies with the comb attached to the leading edge of a flat plate. Examination was carried out at different sweep angles, because life animal clearly show the backward sweep of the wing during gliding and flapping. The results demonstrate a flow turning effect in the boundary layer inboards, which extends along the chord over distances of multiples of the barb lengths. The inboard flow-turning effect described here, thus, counter-acts the outboard directed cross-span flow typically appearing for backward swept wings. From recent theoretical studies on a swept wing, such a way of turning the flow in the boundary layer is known to attenuate crossflow instabilities and delay transition. A comparison of the comb-induced cross-span velocity profiles with those proven to delay transition in theory shows excellent agreement, which supports the laminar flow control hypothesis. Thus, the observed effect is expected to delay transition in owl flight, contributing to a more silent flight

MoonLITE – Technological feasibility of the penetrator concept

Introduction: While the surface missions to the Moon of the 1960s and 1970s achieved a great deal, scientifically a great deal was also left unresolved. The recent plethora of lunar missions (flown or proposed) reflects resurgence in interest in the Moon, not only in its own right, but also as a record of the formation of the Earth-Moon System and the interplanetary environment at 1 AU. Results from orbiter missions have indicated the possible presense of ice within permanently shaded craters at the lunar poles [1] – a situation that, if confirmed, will have profound impacts on lunar exploration

In situ radiometric dating on mars: investigation of the feasibility of K-Ar dating using flight-type mass and X-ray spectrometers

The absolute chronology of Mars is poorly known and as a consequence a key science aim is to perform accurate radiometric dating of martian geological materials. The scientific benefits of in situ radiometric dating are significant and arguably of most importance is the calibration of the martian cratering rate, similar to what has been achieved for the Moon, to reduce the large uncertainties on absolute boundary ages of martian epochs. The Beagle 2 Mars lander was capable of performing radiometric date measurements of rocks using the analyses from two instruments in its payload: (i) the X-ray Spectrometer (XRS) and (ii) the Gas Analysis Package (GAP). We have investigated the feasibility of in situ radiometric dating using the K-Ar technique employing flight-like versions of the Beagle 2 instrumentation. The K-Ar ages of six terrestrial basalts were measured and compared to the ‘control’ Ar-Ar radiometric ages in the range 171 – 1141 Ma. The K content of each basalt was measured by the flight spare XRS and the 40Ar content using a laboratory analogue of the GAP. The K-Ar ages of five basalts broadly agreed with their corresponding Ar-Ar ages. For the final basalt, the 40Ar content was below the detection limit and so an age could not be derived. The precision of the K-Ar ages was ~30% on average. The conclusions from this study are that careful attention must be paid to improving the analytical performance of the instruments, in particular the accuracy and detection limits. The accuracy of the K and Ar measurements are the biggest source of uncertainty in the derived K-Ar age. Having investigated the technique using flight-type planetary instrumentation, we conclude that come of the principle challenges of conducting accurate in situ radiometric dating on Mars using instruments of these types include determining the sample mass, ensuring all the argon is liberated from the sample given the maximum achievable temperature of the mass spectrometer ovens, and argon loss and non-radiogenic argon in the samples analysed

Phosphorus recovery from anaerobically digested liquor of screenings

Phosphorus is a limited resource which is predicted to get exhausted at some point during the twenty-first century. However, it is present in wastewaters at concentrations that come close to supplying the nation’s annual requirements for fertiliser. Many papers have addressed the recovery of phosphorus as struvite (magnesium ammonium phosphate hexahydrate) from different types of waste while the most prominent usage of struvite is as a slow-release fertiliser, suitable as a replacement for chemical fertiliser, for agricultural application. In this study, screenings produced during the wastewater treatment process were anaerobically digested to obtain anaerobically digested liquor which was subsequently used for phosphorus recovery in the form of struvite. This was carried out at different concentrations of dry solids. The amount of struvite potential was calculated theoretically using molar ratio calculations of 1:1:1 (Mg:N:P). From the results, it was found that the digestate is high in phosphorus content and can be recovered up to 41%. For struvite yield, 0.27,kg of struvite can be recovered from each kg dry solids of screenings from 3% of dry solids. Screenings thus prove a valuable source of additional phosphorus which current disposal practices fail to exploit

Saturn's equinoctial auroras

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95061/1/grl26673.pd

MoonLITE programmatic and technological update

MoonLITE is a proposed four penetrator lunar mission. Following a US/UK working group assessment, a science assessment and the first UK impact trials, a full mission-level phase A study has begun. A technological and programmatic update of the mission is given

Simultaneous Cassini VIMS and UVIS observations of Saturn's southern aurora: Comparing emissions from H, H-2 and H-3(+) at a high spatial resolution

Here, for the first time, temporally coincident and spatially overlapping Cassini VIMS and UVIS observations of Saturn's southern aurora are presented. Ultraviolet auroral H and H-2 emissions from UVIS are compared to infrared H-3(+) emission from VIMS. The auroral emission is structured into three arcs - H, H-2 and H-3(+) are morphologically identical in the bright main auroral oval (similar to 73 degrees S), but there is an equatorward arc that is seen predominantly in H (similar to 70 degrees S), and a poleward arc (similar to 74 degrees S) that is seen mainly in H-2 and H-3(+). These observations indicate that, for the main auroral oval, UV emission is a good proxy for the infrared H-3(+) morphology (and vice versa), but for emission either poleward or equatorward this is no longer true. Hence, simultaneous UV/IR observations are crucial for completing the picture of how the atmosphere interacts with the magnetosphere