X-ray photoelectron spectroscopy reveals that the remarkable electronic quality of GaAs/sulfide interfaces can be ascribed to the formation of AsxSy phases which grow on an oxide-free GaAs surface. While one of these phases is akin to As2S3, another shows significant in-plane S—S bonding. Raman experiments indicate that the band bending on this disulfide- terminated surface has been reduced to 0.12 eV.

Passivating AsxSy phases that form on GaAs after reactions with aqueous sulfides [Na2S⋅9H2O and (NH4)2S] decompose in the presence of oxygen and light, producing a surface composed primarily of As2O3. X-ray photoelectron spectroscopy (XPS) shows that (NH4)2 S-treated surfaces degrade in two steps with the initial AsxSy (present as a disulfide) degrading by S–S bond cleavage to yield As2O3 and an As2S3 phase like the one that forms on GaAs after Na2S⋅9H2O reactions. XPS reveals little decomposition of surface sulfides in the presence of light or oxygen alone, showing that GaAs passivation could be made long-lived if either is rigorously excluded.

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Four experiments examined young children's understanding of the inverse relation between the number of parts into which a quantity is to be divided and the size of each part. In Experiment 1 5-, 6-, and 7-year-old children tended to judge, incorrectly, that bigger shares would result from sharing with more, rather than fewer, recipients. In Experiment 2, 5-year-olds correctly recognized the inverse effect of additional recipients when the sharing was based on subtraction rather than on equal partitioning. In Experiment 3, a modification of the equal-sharing task from Experiment 1 designed to reduce cognitive complexity successfully elicited correct performance from 7-year-olds but not from 5-year-olds. However, 5-year-olds markedly improved when they were given a chance to compare the outcomes of sharing with different numbers of recipients. Experiment 4 corroborated and extended this evidence of learning.