The Influence of overlaying solvent on the environment and structure of polymeric C18, alkylated silica surfaces Is studied by using the fluorescence of pyrene as a probe. Intensity ratios of vibronic emission bands are used to determine changes In polarity around the probe sorbed to the C18 surface, while quenching of fluorescence by potassium Iodide Is used to correlate those changes to exposure of pyrene to the mobile phase. Two distinct regions of stationary phase behavior are Identified. At high concentrations of methanol In the mobile phase, pyrene Is partitioned or fully surrounded by alkyl chains which are apparently well solvated by methanol. At lower concentrations of methanol, the Increase In surface polarity and onset of quenching by solution phase Ions Indicate that some fraction of sorbed pyrene Is exposed to the surrounding solvent as the stationary phase volume collapses. Under these conditions, a significantly greater heterogeneity In the polarity of sorption environments Is observed, where a fraction of the fluorescent probe molecules Is partitioned Into nonpolar domains which are Inaccessible to a sorbed polar quencher.

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Tyrosine 411 of human albumin is an established site for covalent attachment of 10-fluoroethoxyphosphinyl-N-biotinamidopentyldecanamide (FP-biotin), diisopropylfluorophosphate, chlorpyrifos oxon, soman, sarin, and dichlorvos. This work investigated the hypothesis that other residues in albumin could be modified by organophosphorus agents (OP). Human plasma was aggressively treated with FP-biotin; plasma proteins were separated into high and low abundant portions using a proteome partitioning antibody kit, and the proteins were digested with trypsin. The FP-biotinylated tryptic peptides were isolated by binding to monomeric avidin beads. The major sites of covalent attachment identified by mass spectrometry were Y138, Y148, Y401, Y411, Y452, S232, and S287 of human albumin. Prolonged treatment of pure human albumin with chlorpyrifos oxon labeled Y138, Y150, Y161, Y401, Y411, and Y452. To identify the most reactive residue, albumin was treated for 2 h with DFP, FP-biotin, chlorpyrifos oxon, or soman, digested with trypsin or pepsin, and analyzed by mass spectrometry. The most reactive residue was always Tyr 411. Diethoxyphosphate-labeled Tyr 411 was stable for months at pH 7.4. These results will be useful in the development of specific antibodies to detect OP exposure and to engineer albumin for use as an OP scavenger.

Language maps signals onto meanings through the use of two distinct types of structure. First, the space of meanings is discretized into categories that are shared by all users of the language. Second, the signals employed by the language are compositional: The meaning of the whole is a function of its parts and the way in which those parts are combined. In three iterated learning experiments using a vast, continuous, open‐ended meaning space, we explore the conditions under which both structured categories and structured signals emerge ex nihilo. While previous experiments have been limited to either categorical structure in meanings or compositional structure in signals, these experiments demonstrate that when the meaning space lacks clear preexisting boundaries, more subtle morphological structure that lacks straightforward compositionality—as found in natural languages—may evolve as a solution to joint pressures from learning and communication.