Space shuttle ice nuclei

With the advent of the space shuttle era, increasing rocket activity is expected in the Earth's upper atmosphere. The space shuttle solid-fuelled booster rockets emit ∼150 tonnes of alumina (Al2O3) particles per launch, much of which spreads throughout the upper troposphere and stratosphere1. Such particles can seed aerosols and clouds, and might therefore cause changes in the terrestrial radiation balance and climate2. Estimates are made here showing that average ice nuclei concentrations in the upper troposphere could increase by a factor of 2, and that an aluminium dust layer weighing up to 1,000 tonnes might eventually form in the lower stratosphere. © 1982 Nature Publishing Group

Multiphysical characterization of FSW of aluminum electrical busbars with copper ends

This work investigates the benefits of having an aluminum (Al) busbar with welded copper (Cu) ends, and evaluates the force relaxation phenomena of a pre-loaded bolt joint on Cu versus Al, under cyclic thermal loading. The results show a force relaxation rate 50% lower in the Cu-bolted joint compared with the one in Al. The core of this research is the weldability analysis of Al-Cu butt joints made by friction stir welding (FSW). The materials are AA1050 H14/24 and Cu OF 04 with thickness of 6 mm. Temperature monitoring during the FSW cycle emphasize how heat generation depends mostly on local internal viscoplastic deformation. Tensile, bending, and microhardness tests were used to establish the mechanical properties. Optical microscope and scanning electron microscopy were used to characterize the microstructure. Joining mechanisms in the weld were investigated using energy-dispersive X-ray spectroscopy. The FSW resulted in 85% tensile strength efficiency compared to the Al base material, and 97% electrical conductivity efficiency compared to an ideal bimetallic component made of the same materials with no contact resistance. Electrical resistance of the FSW is 200 times lower than the electrical contact resistance between the Al-Cu materials while under high compressive force.Peer reviewe

Prostaglandin D2 amplifies lupus disease through basophil accumulation in lymphoid organs

In a lupus environment, basophils accumulate in secondary lymphoid organs where they affect pathogenesis by stimulating autoantibody production. Here the authors show this accumulation is driven by PGD2-induced CXCR4 surface expression and trafficking of basophils