Wetting films on chemically heterogeneous substrates

Based on a microscopic density functional theory we investigate the morphology of thin liquidlike wetting films adsorbed on substrates endowed with well-defined chemical heterogeneities. As paradigmatic cases we focus on a single chemical step and on a single stripe. In view of applications in microfluidics the accuracy of guiding liquids by chemical microchannels is discussed. Finally we give a general prescription of how to investigate theoretically the wetting properties of substrates with arbitrary chemical structures.Comment: 56 pages, RevTeX, 20 Figure

Search for the Chiral Magnetic Effect in Au+Au collisions at sNN=27\sqrt{s_{_{\rm{NN}}}}=27 GeV with the STAR forward Event Plane Detectors

A decisive experimental test of the Chiral Magnetic Effect (CME) is considered one of the major scientific goals at the Relativistic Heavy-Ion Collider (RHIC) towards understanding the nontrivial topological fluctuations of the Quantum Chromodynamics vacuum. In heavy-ion collisions, the CME is expected to result in a charge separation phenomenon across the reaction plane, whose strength could be strongly energy dependent. The previous CME searches have been focused on top RHIC energy collisions. In this Letter, we present a low energy search for the CME in Au+Au collisions at $\sqrt{s_{_{\rm{NN}}}}=27$ GeV. We measure elliptic flow scaled charge-dependent correlators relative to the event planes that are defined at both mid-rapidity $|\eta|<1.0$ and at forward rapidity $2.1 < |\eta|<5.1$. We compare the results based on the directed flow plane ($\Psi_1$) at forward rapidity and the elliptic flow plane ($\Psi_2$) at both central and forward rapidity. The CME scenario is expected to result in a larger correlation relative to $\Psi_1$ than to $\Psi_2$, while a flow driven background scenario would lead to a consistent result for both event planes[1,2]. In 10-50\% centrality, results using three different event planes are found to be consistent within experimental uncertainties, suggesting a flow driven background scenario dominating the measurement. We obtain an upper limit on the deviation from a flow driven background scenario at the 95\% confidence level. This work opens up a possible road map towards future CME search with the high statistics data from the RHIC Beam Energy Scan Phase-II.Comment: main: 8 pages, 5 figures; supplementary material: 2 pages, 1 figur

Interaction of triosmium complexes with hydrogen chloride: A model for fine-tuning regioselective protonation in metal clusters

The reaction of Os-3(CO)(10)(CNR)(NCMe) (1) with HCl was studied and this system was found to be a good model for observing the fine-tuning of site-selective protonation in metal complexes. Three products including the protonated species [(mu-H)Os-3(CO)(10)(CNR)(NCMe)]Cl-+(-) (2), the bridging aminocarbyne complex (mu-Cl)Os-3(CO)(10)(mu(2)-C = NHR) (3), and the hydride derivative (mu-H)Os3Cl(CO)(10)(CNR) (4) were obtained for the reaction. The site of protonation, either on the Os center or on the nitrogen atom of coordinated isocyanide, was tuned in a sensitive manner by the nature of the coordinated isocyanides, the polarity of the solvents, and the strengths of the acids, leading to different product distributions. The more electron withdrawing isocyanides (CNCH2Ph, CNPh) favor the formation of the aminocarbyne complex 3. In a nonpolar solvent like cyclohexane the reaction afforded 3 as the main product. Furthermore, complex 2 was converted to (mu-H)Os-3(CO)(10)(mu(2)-CONHR) (5) upon hydrolysis, in which the coordinated isocyanide was transformed to a carboxamido group. This was verified by obtaining the deuterated species (mu-H) Os-3(CO)(10)(mu(2)-CONDPr) when [(mu-H)Os-3(CO)(10)(CNPr)(NCMe)]Cl-+(-) (2a) was treated with D2O in THF. The molecular structures of (mu(2)-Cl)Os-3(CO)(10) (mu(2)-C = NHCH2Ph) (3b) and (mu-H)Os3Cl(CO)(10)(CNPr) (4a) were determined by X-ray diffraction analyses. Complex 3b contains both bridging chloride and bridging aminocarbyne groups, whereas 4a contains a terminal chloride, a terminal isocyanide and a bridging hydride