Characterisation of candidate members of (136108) Haumea's family: II. Follow-up observations

From a dynamical analysis of the orbital elements of transneptunian objects (TNOs), Ragozzine & Brown reported a list of candidate members of the first collisional family found among this population, associated with (136108) Haumea (a.k.a. 2003 EL61). We aim to distinguish the true members of the Haumea collisional family from interlopers. We search for water ice on their surfaces, which is a common characteristic of the known family members. The properties of the confirmed family are used to constrain the formation mechanism of Haumea, its satellites, and its family. Optical and near-infrared photometry is used to identify water ice. We use in particular the CH4 filter of the Hawk-I instrument at the European Southern Observatory Very Large Telescope as a short H-band (Hs), the (J-Hs) colour being a sensitive measure of the water ice absorption band at 1.6 {\mu}m. Continuing our previous study headed by Snodgrass, we report colours for 8 candidate family members, including near-infrared colours for 5. We confirm one object as a genuine member of the collisional family (2003 UZ117), and reject 5 others. The lack of infrared data for the two remaining objects prevent any conclusion from being drawn. The total number of rejected members is therefore 17. The 11 confirmed members represent only a third of the 36 candidates. The origin of Haumea's family is likely to be related to an impact event. However, a scenario explaining all the peculiarities of Haumea itself and its family remains elusive.Comment: 8 pages, 4 figures, accepted for publication in A&

Physicochemical characterization of the PEG8000-Na2SO4 aqueous two-phase system

The polyethylene glycol-sodium sulfate aqueous two-phase system has been characterized at 23 °C. Tielines for the phase diagram were obtained experimentally. Phases in equilibrium were characterized by means of the solvatochromic parameters π*, α, and β, which provide a measurement of the polarity/polarizability and the H-bond donor and acceptor abilities, respectively. The ability of the phases to participate in hydrophobic interactions was characterized by means of the free energy of transfer of a methylene group between the conjugated phases, using the partition of a homologous series of dinitrophenylated amino acids. The results show the effect of the presence of polymer and salt in the aqueous phase, and a comparison of both phases with pure water is made.LSRE-PortoUniversidade Católica PortuguesaEscola Superior de Biotecnologia do PortoFundação para a Ciência e a Tecnologia (FCT

Atomic Layer Deposition (ALD) to Mitigate Tin Whisker Growth and Corrosion Issues on Printed Circuit Board Assemblies

This paper presents the results of a research program set up to evaluate atomic layer deposition (ALD) conformal coatings as a method of mitigating the growth of tin whiskers from printed circuit board assemblies. The effect of ALD coating process variables on the ability of the coating to mitigate whisker growth were evaluated. Scanning electron microscopy and optical microscopy were used to evaluate both the size and distribution of tin whiskers and the coating/whisker interactions. Results show that the ALD process can achieve significant reductions in whisker growth and thus offers considerable potential as a reworkable whisker mitigation strategy. The effect of ALD layer thickness on whisker formation was also investigated. Studies indicate that thermal exposure during ALD processing may contribute significantly to the observed whisker mitigation