We study the adsorption of a fluid in the grand canonical ensemble occurring at a planar heterogeneous wall which is decorated with a chemical stripe of width L. We suppose that the material of the stripe strongly preferentially adsorbs the liquid in contrast to the outer material which is only partially wet. This competition leads to the nucleation of a droplet of liquid on the stripe, the height h m and shape of which (at bulk two-phase coexistence) has been predicted previously using mesoscopic interfacial Hamiltonian theory. We test these predictions using a microscopic Fundamental Measure Density Functional Theory which incorporates shortranged fluid-fluid and fully long-ranged wall-fluid interactions. Our model functional accurately describes packing effects not captured by the interfacial Hamiltonian but still we show that there is excellent agreement with the predictions h m ≈ L 1/2 and for the scaled circular shape of the drop even for L as small as 50 molecular diameters. For smaller stripes the droplet height is considerably lower than that predicted by the mesoscopic interfacial theory. Phase transitions for droplet configurations occurring on substrates with multiple stripes are also discussed.

Using mesoscopic interfacial models and microscopic density functional theory we study fluid adsorption at a dry wall decorated with three completely wet stripes of width L separated by distances D1 and D2. The stripes interact with the fluid with long-range forces inducing a large finite-size contribution to the surface free-energy. We show that this non-extensive free-energy contribution scales with ln L and drives different types of bridging transition corresponding to the merging of liquid drops adsorbed at neighbouring wetting stripes when the separation between them is molecularly small. We determine the surface phase diagram and show that this exhibits two triple points, where isolated drops, double drops and triple drops coexist. For the symmetric case, D1 = D2 ≡ D, our results also confirm that the equilbrium droplet configuration always has the symmetry of the substrate corresponding to either three isolated drops when D is large or a single triple drop when D is small; however, symmetry broken configurations do occur in a metastable part of the phase diagram which lies very close to the equilibrium bridging phase boundary. Implications for phase transitions on other types of patterned surface are considered. arXiv:1905.00308v1 [cond-mat.stat-mech] 1 May 2019

Styrene 7,8-oxide (SO), a reactive metabolic intermediate of the industrial chemical styrene, binds covalently at nucleophilic amino acid residues of blood proteins in vivo and in vitro. In this study, SO adducts with cysteine, lysine, and histidine were synthesized, characterized, and then used as authentic standards to assign and quantitate the SO adducts in globin incubated with SO. S-(2-Hydroxy-1-phenylethyl)cysteine and S-(2-hydroxy-2-phenylethyl)cysteine were prepared by direct alkylation of cysteine with (R)-SO or (S)-SO. To prepare the SO adducts with lysine and histidine, Nalpha-Boc-protected amino acids were alkylated with (R)-SO or (S)-SO followed by deprotection of the Boc group to obtain Nepsilon-(2-hydroxy-1-phenylethyl)lysine and Nepsilon-(2-hydroxy-2-phenylethyl)lysine as well as Npi-(2-hydroxy-1-phenylethyl)histidine, Npi-(2-hydroxy-2-phenylethyl)histidine, Ntau-(2-hydroxy-1-phenylethyl)histidine, and Ntau-(2-hydroxy-2-phenylethyl)histidine. The individual regioisomers were isolated from their mixtures by semipreparative HPLC, and their structure was assigned using NMR techniques. The SO-modified globin, isolated from human hemoglobin incubated in vitro with racemic SO at a molar ratio SO/globin of 100:1 or 10:1, was digested with pronase and subjected to LC/MS and GC/MS analysis. All known regioisomers of the SO adducts were detected, with S-(2-hydroxy-1-phenylethyl)cysteine, Nepsilon-(2-hydroxy-1-phenylethyl)lysine, and Ntau-(2-hydroxy-2-phenylethyl)histidine being the most abundant in the modified globin. Deuterated analogues of the SO adducts were employed as internal standards. The SO-amino acid adducts described here appear to be suitable biomarkers for long-term exposures to styrene or SO.

Using coarse-grained Brownian dynamics simulations, we study the relationship between hydrodynamic radius ([Formula: see text] and the lateral size ([Formula: see text] of dispersed nanosheets. Our simulation results show that the bending modulus of the nanosheets has a significant impact on the exponent of this power-law relationship between the radius of gyration (and thus [Formula: see text] and [Formula: see text] The exponent can vary from 0.17 to 1. This sheds light on the interpretation of dynamic light scattering (DLS) measurements, such that DLS data can capture both nanosheet lateral size and modulus (which is, in turn, affected by nanosheet thickness).