Saturated hydrocarbon polymeric binder for advanced solid propellant and hybrid solid grains Quarterly report no. 3, 1 May - 31 Jul. 1966

Saturated hydrocarbon polymeric binder for advanced solid propellant and hybrid solid grain

Saturated hydrocarbon polymeric binder for advanced solid propellant and hybrid solid grains Quarterly report no. 2, 1 Feb. - 30 Apr. 1966

Synthesis and analysis of ethylene-neohexene copolymers with other non ketene-imine group free radicals for solid and hybrid grain propellant saturated hydrocarbon binder progra

Characterization of mesostasis areas in mare basalts: constraining melt compositions from which apatite crystallizes

Crystallization of major silicate and oxide phases from basaltic melts produces late-stage liquids whose chemical compositions differ from the initial melt. These chemically evolved liquids crystallize phases in the interstitial mesostasis regions in lunar basaltic rocks. Enrichment of incompatible elements, including volatiles such as OH, F, Cl, is characteristic of these late-stage liquids and encourages growth of accessory phases including apatite [Ca5(PO4)2(F,Cl,OH)]. Apatite is the main volatile bearing crystalline phase in lunar rocks. It starts crystallizing after ~95% melt solidification in typical mare basalts, but could crystallize earlier, after ~85-90% solidification in KREEP basalts. Using the OH contents of apatites, several researchers have calculated water contents for parental magmas. These calculated parental magma water contents can then be used to estimate a range of values for water in the mantle source regions of mare basalts [e.g.,2-6]. Therefore, a better characterization of the mesostasis areas, and of the melts in which apatite forms, is paramount to gain further insights and constraints on water in the lunar interior, especially because important parameters such as partitioning of volatiles between late-stage melts and apatite remain poorly constrained

Why is timing of bird migration advancing when individuals are not?

Recent advances in spring arrival dates have been reported in many migratory species but the mechanism driving these advances is unknown. As population declines are most widely reported in species that are not advancing migration, there is an urgent need to identify the mechanisms facilitating and constraining these advances. Individual plasticity in timing of migration in response to changing climatic conditions is commonly proposed to drive these advances but plasticity in individual migratory timings is rarely observed. For a shorebird population that has significantly advanced migration in recent decades, we show that individual arrival dates are highly consistent between years, but that the arrival dates of new recruits to the population are significantly earlier now than in previous years. Several mechanisms could drive advances in recruit arrival, none of which require individual plasticity or rapid evolution of migration timings. In particular, advances in nest-laying dates could result in advanced recruit arrival, if benefits of early hatching facilitate early subsequent spring migration. This mechanism could also explain why arrival dates of short-distance migrants, which generally return to breeding sites earlier and have greater scope for advance laying, are advancing more rapidly than long-distance migrants

Controlling cyanobacterial harmful blooms in freshwater ecosystems

Cyanobacteria's long evolutionary history has enabled them to adapt to geochemical and climatic changes, and more recent human and climatic modifications of aquatic ecosystems, including nutrient over-enrichment, hydrologic modifications, and global warming. Harmful (toxic, hypoxia-generating, food web altering) cyanobacterial bloom (CyanoHAB) genera are controlled by the synergistic effects of nutrient (nitrogen and phosphorus) supplies, light, temperature, water residence/flushing times, and biotic interactions. Accordingly, mitigation strategies are focused on manipulating these dynamic factors. Strategies based on physical, chemical (algaecide) and biological manipulations can be effective in reducing CyanoHABs. However, these strategies should invariably be accompanied by nutrient (both nitrogen and phosphorus in most cases) input reductions to ensure long-term success and sustainability. While the applicability and feasibility of various controls and management approaches is focused on freshwater ecosystems, they will also be applicable to estuarine and coastal ecosystems. In order to ensure long-term control of CyanoHABs, these strategies should be adaptive to climatic variability and change, because nutrient-CyanoHAB thresholds will likely be altered in a climatically more-extreme world

Using lunar apatite to assess the volatile inventory of the Moon

Lunar petrology, most notably the absense of hydrous minerals (such as micas and amphiboles) and the lack of Fe2O3, imply a low oxygen activity for the Moon. The anhydrous nature of the Moon is consistent with observed depletions in volatile elements compared to the Earth. Recent analytical developments have led to the re-investigation of lunar samples. In volcanic products, heterogeneous water contents in volcanic glass beads olivine-hosted melt inclusions and in the accessory phase apatite indicate a wetter lunar interior than previously thought. Analysis of lunar apatite has produced OH contents as high as ~12000 ppm and volatile contents of olivine-hosted melt inclusions appear to be similar to terrestrial mid-ocean ridge basalts values. However, analysis of Cl isotope compositions from a range of lunar rocks (basalts, glasses, apatite grains) identified a Cl fractionation 25 times larger than on Earth. This has been interpreted as reflecting a relatively dry lunar interior. The coupled nature of Cl and H, together with this high fractionation of Cl has been used to suggest the Moon’s mantle has H values as low as 10 ppb. To calculate the volatile contents of lunar melts, the partitioning behaviour of volatiles into apatite must be considered. Very little work has been done on the partition of volatiles under lunar conditions, however to fully constrain the H content of the magmatic source regions based on apatite grain measurements, determination of accurate partition coefficients is required. Experimental work using a piston-cylinder assembly at VU, University Amsterdam, is being carried out to derive these partition coefficients for volatiles (F, OH, Cl) between apatite and melts. Measurements of the volatile contents in experimental synthesised apatites are being carried out using a Cameca NanoSIMS 50L ion probe at the Open University. Primary experiments have looked at the temperature effect of F partitioning into apatite. This experimental work will be combined with measurements of Cl, F, and OH concentrations as well as Cl and H isotope compositions in mare basalts. This will provide better constraints on the volatile budget of the lunar magmatic source regions