As-placed contact angles for sessile drops

As-placed contact angle is the contact angle a drop adapts as a result of its placement on a surface. As expected, the as-placed contact angle, thetaAP, of a sessile drop on a horizontal surface decreases with the drop size due to the increase in hydrostatic pressure. We present a theoretical prediction for thetaAP which shows that it is a unique function of the advancing contact angle, thetaA, drop size, and material properties (surface tensions and densities). We test our prediction with published and new data. The theory agrees with the experiments. From the relation of the as-placed contact angle to drop size the thermodynamic equilibrium contact angle is also calculated.     

Ti-catalyzed reformatsky-type coupling between alpha-halo ketones and aldehydes

We describe the first Ti-catalyzed Reformatsky-type coupling between alpha-halo ketones and aldehydes. The reaction affords beta-hydroxy ketones under mild, neutral conditions compatible with ketones and other electrophiles. The catalytic cycle possibly proceeds via bis(cyclopentadienyl)titanium enolates.     

Planar tetracoordinate carbons in cyclic semisaturated hydrocarbons

A series of planar tetracoordinate carbon molecules in cyclic semisaturated hydrocarbons resulting from the combination of the C5(2-) skeleton with saturated hydrocarbon fragments is reported. The electronic stabilization and the bonding situation are studied through the analyses of molecular orbitals and the electron localization function. The magnetic properties are also revised, giving particular attention to the induced magnetic field. These systems are the first semisaturated cycles containing a planar tetracoordinate carbon stabilized only by electronic factors.     

On a Drift–Diffusion System for Semiconductor Devices

In this note, we study a fractional Poisson–Nernst–Planck equation modeling a semiconductor device. We prove several decay estimates for the Lebesgue and Sobolev norms in one, two and three dimensions. We also provide the first term of the asymptotic expansion as \({t\rightarrow\infty}\).     

Synthesis of Dihydroindolo[2,3‐c]carbazole as Potential Telomerase Inhibitor

The dictyodendrins A–E were the first marine natural products that show inhibition of telomerase. A versatile and convergent route was described for the synthesis of derivatives of these pyrrolo[2,3‐c]carbazole alkaloids as potential inhibitors of telomerase, by cyclotrimerization [2 + 2 + 2] of ruthenium‐catalyzed diynamides diarylacetylenes.     

Computational studies of stable hexanuclear CulAgmAun (l + m + n = 6; l,m, n > 0) clusters

A DFT study was carried out on the ground state structures of ternary Cu_lAg_mAu_n (l + m + n = 6) clusters, with the aim of investigating changes of thermal and kinetic stabilities as an effect of composition, as well as the composition dependence of the electrostatic potential, of stable planar structures. DFT optimizations were performed using the PBE functional and the SDD basis set. All the optimized structures adopt planar geometries with bent triangular structures. Calculated binding energy values are in the range 1.5–1.9 eV/atom, which shows their thermal stability. The predicted HOMO‐LUMO energy gap values are in the semiconductor region, providing a qualitative indication of a moderate kinetic stability. NBO analyses indicate the existence of two mechanisms promoting planar structural stability, one due to bonding‐antibonding orbital interaction, and the other one due to the well‐known spd hybridization. Wiberg indices were obtained showing interatomic bonding. Electrostatic potential calculations show the existence of nucleophilic attack regions preferentially around silver and copper atoms located at the vertices while electrophilic attack regions are found in the vicinity of gold atoms over the cluster plane. Apparently, charge transfer occurs toward gold from silver and copper atoms when the concentration is favorable in the proximity of gold atoms. In particular, if the small ternary clusters discussed here contain only one gold atom, then a high electron density is observed at the site of this gold atom. © 2016 Wiley Periodicals, Inc.     

Coagulant Activity of Water-Soluble <Emphasis Type="Italic">Moringa oleifera</Emphasis> Lectin Is Linked to Lowering of Electrical Resistance and Inhibited by Monosaccharides and Magnesium Ions

Moringa oleifera seeds contain a water-soluble lectin [water-soluble M. oleifera lectin (WSMoL)] that has shown coagulant activity. Magnesium ions are able to interfere with the ability of this lectin to bind carbohydrates. In this study, we performed structural characterization of WSMoL and analyzed its effect on the electrical resistance of a kaolin clay suspension in both presence and absence of monosaccharides (N-acetylglucosamine, glucose, or fructose) and magnesium ions. The coagulant activity of WSMoL was monitored by measuring optical density and electrical resistance over a period of 60 min. Native WSMoL had a molecular mass of 60 kDa and exhibited anionic nature (pI 5.5). In sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE), it appeared as three polypeptide bands of 30, 20, and 10 kDa. WSMoL reduced the optical density and electrical resistance of the kaolin suspension, which suggests that suspended particles are destabilized and that this is followed by formation of complexes. The coagulant activity of lectin decreased in the presence of Mg²⁺ ions and carbohydrates at concentrations that also inhibited hemagglutinating activity. This was most likely due to conformational changes in lectin structure. Our findings suggest that the coagulant activity of WSMoL is enhanced by lowering of electrical resistance of the medium and is impaired by lectin–carbohydrate and lectin–Mg²⁺ interactions.     

Tristimulus analysis for sensors set with either positive or negative sensitivities—determination of the relative concentration of an analyte in a binary mixture

We consider the general case of a set of three sensors that show a response proportional to analyte concentration and apply tristimulus analysis to represent the set of responses as tristimulus coordinates in a two-dimensional representation. These coordinates are a signature of the analyte and can be used for analyte identification. We extend the tristimulus analysis for cases where the sensors may present either positive or negative sensitivities, a situation in which the usual tristimulus analysis has limitations. We propose a different approach, taking the coordinates where the tristimulus vector crosses the unitary radius spherical shell, taking the angular coordinates as signature of the analyte. We also consider the case of binary mixtures and derive the set of equations that can be used to determine the relative concentration of each one of the analytes in the binary mixture from the tristimulus coordinates of the mixture.