Abstract-Here, we report the identification of 69 tracks in approximately 250 cm 2 of aerogel collectors of the Stardust Interstellar Dust Collector. We identified these tracks through Stardust@home, a distributed internet-based virtual microscope and search engine, in which > 30,000 amateur scientists collectively performed >9 9 10 7 searches on approximately 10 6 fields of view. Using calibration images, we measured individual detection efficiency, and found that the individual detection efficiency for tracks > 2.5 lm in diameter was >0.6, and was >0.75 for tracks >3 lm in diameter. Because most fields of view were searched >30 times, these results could be combined to yield a theoretical detection efficiency near unity. The initial expectation was that interstellar dust would be captured at very high speed. The actual tracks discovered in the Stardust collector, however, were due to low-speed impacts, and were morphologically strongly distinct from the calibration images. As a result, the detection efficiency of these tracks was lower than detection efficiency of calibrations presented in training, testing, and ongoing calibration. Nevertheless, as calibration images based on low-speed impacts were added later in the project, detection efficiencies for lowspeed tracks rose dramatically. We conclude that a massively distributed, calibrated search, with amateur collaborators, is an effective approach to the challenging problem of identification of tracks of hypervelocity projectiles captured in aerogel. 1510 A. J. Westphal et al.

Here we describe the critical role that synchrotron X-ray and infrared microprobes are playing in the search for interstellar dust in the Stardust Interstellar Dust Collector (SIDC). The samples under examination are submicron particles trapped in low-density aerogel. We have found that the spatial resolution, energy range, and flux capabilities of the FTIR beamlines 1.4.3, ALS, and U2B, NSLS; the XRF microprobes ID13 and ID22NI, ESRF and 2-ID-D, APS; and the STXM beamline 11.0.2, ALS are ideally suited for studying these tiny returned samples. Using nondestructive, coordinated analyses at these microprobes, we have been able to eliminate most candidates as likely samples of interstellar dust. This in itself is a major accomplishment, since the analysis of these tiny samples is technically extremely challenging.

Zinc(II) formaldehyde sulfoxylate, [Zn(CH3O3S)2], a widely marketed additive in the polymer and textile industry (under the registered trademarks Decroline, Decolin and Safolin, CAS 24887‐06‐7), possesses, in the solid state, a polymeric framework, with the Zn atoms octa­hedrally coordinated by six O atoms of four different hydroxy­methane­sulfinate groups. The latter are found to coordinate through all their O atoms, including the hydr­oxy ones, and possess a chelating nature. By contrast, in the structure of the only other commercially available salt of this ligand (dihydrated sodium formaldehyde sulfoxylate), the organic residue, being involved in an extensive network of hydrogen‐bond contacts, is fully stretched and bridges two NaI ions through a single O atom.