The multi-player nonzero-sum Dynkin game in discrete time

We study the infinite horizon discrete time N-player nonzero-sum Dynkin game ( $N \ge 2$ ) with stopping times as strategies (or pure strategies). The payoff depends on the set of players that stop at the termination stage (where the termination stage is the minimal stage in which at least one player stops). We prove existence of a Nash equilibrium point for the game provided that, for each player $\pi _i$ and each nonempty subset $S$ of players that does not contain $\pi _i$ , the payoff if $S$ stops at a given time is at least the payoff if $S$ and $\pi _i$ stop at that time.     

Surface Activity of Novel Polymerizable Anionic Polyoxyethylene 4-Nonyl-2-Prpylene-Phenyl Ether Ammonium Sulfate Succinate Surfactants

Novel polymerizable surface-active monomers were synthesized by successive treatment of polyoxyethylene 4-nonyl-2-prpylene-phenyl ether ammonium sulfate with maleic anhydride in the presence of hydroquinone at temperature of 180°C. The molecular structures of the polymerizable surfactants were confirmed by ¹H and ¹³C NMR spectroscopy. The surface tension isotherms on the air-water solution interface were obtained. The critical micelle concentrations (cmc) as well as the surface tension at the cmc were determined for these substances. The micellization and adsorption of the prepared anionic surfactants have been investigated by surface tension, and cloud point measurements. Surface parameters such as surface excess concentration (Γ _max), the area per molecule at interface (A _min) and the effectiveness of surface tension reduction (π_CMC) were determined from the adsorption isotherms of the prepared surfactants.      

Synthesis and Evaluation of Some Schiff Base Surfactants for Treating Crude Oil Emulsions

Water soluble nonionic surfactants based on Schiff base monomers were prepared by their etherification with β,^` β- dichlorodiethylether and PEG 400 in presence of NaOH. The surface properties of the prepared surfactants were determined by measuring the surface tension at different temperatures. The prepared nonionic surfactants were evaluated as demulsifiers for synthetic water in crude-oil emulsions that were pronounced at different ratios of crude oil: water at 45°C and 60°C. The experimental results showed that the dehydration rate of the prepared demulsifiers reached 90% and 100% at some concentrations.     

A DFT study of substrate effect on the magnetism of V(001) surface

The effect of isoelectric transition metals (TM) Nb and Ta on the magnetism of the V(001) surface is investigated from first principles using Density functional theory (DFT), with the generalized gradient approximation (GGA). Ferromagnetic (FM) moments of 2.5 μ_B and 2.2 μ_B are obtained for the relaxed surface V monolayer (ML) in the V/Nb(001) and the V/Ta(001) systems respectively, at T = 0 K. The values are almost twice of those obtained with Mo and W of group VIB and can be attributed to the comparatively smaller bandwidths of the substrates Nb and Ta. Small induced magnetic moments are present on the Nb and Ta interfacial layers, which are coupled anti-ferromagnetically with the V ML.     

Chiral nematic assemblies of silver nanoparticles in mesoporous silica thin films

Silver nanoparticles (NPs) have been synthesized inside mesoporous silica films with chiral nematic structure. Circular dichroism measurements of the silver NP-loaded silica films show NP-based optical activity in the vicinity of the surface plasmon resonance. These materials, with an optical response associated with the chiral assembly of metal NPs, may be useful for developing new sensors.     

Site‐Selective Late‐Stage Aromatic [18F]Fluorination via Aryl Sulfonium Salts

Site‐selective functionalization of C?H bonds in small complex molecules is a long‐standing challenge in organic chemistry. Herein, we report a broadly applicable and site‐selective aromatic C?H dibenzothiophenylation reaction. The conceptual advantage of this transformation is further demonstrated through the two‐step C?H [¹⁸F]fluorination of a series of marketed small‐molecule drugs.     

Some Reactions of 2-Amino-3-Cyano-Substituted Pyrroles

Reactivity of 2-amino-3-cyano-4.5-disubstituted pyrroles was studied and data for structural assignment are reported.     

Polymer and Mesoporous Silica Microspheres with Chiral Nematic Order from Cellulose Nanocrystals

Polymer microspheres with chiral nematic order were obtained from an emulsion polymerization technique using cellulose nanocrystals (CNCs) as the template. The growth of the liquid crystals from tiny tactoids to droplets with spherical symmetry was captured and investigated by both optical and electron microscopy for the first time. The size of the microspheres could be tuned between tens and hundreds of micrometers; to obtain single, integrated chiral nematic kernels, the size of water droplets in the emulsion should be similar to that of CNC tactoids. Through a double‐matrix templating method, novel silica microspheres with chiral nematic order were fabricated, which showed a high surface area and mesoporosity. The methods developed here may help to reveal the evolution of other self‐assembling systems, and these materials have potential applications in optical devices and chiral separations.     

Clustering of glycine molecules in aqueous solution studied by molecular dynamics simulation

The nature of glycine--glycine interactions in aqueous solution has been studied using molecular dynamics simulations at four different concentrations and, in each case, four different temperatures. Although evidence is found for formation of small, transient hydrogen-bonded clusters of glycine molecules, the main type of interaction between glycine molecules is found to be single NH...OC hydrogen bonds. Double-hydrogen-bonded "dimers", which have often been cited as a significant species present in aqueous solutions of glycine, are only observed infrequently. When double-hydrogen-bonded dimers are formed, they dissociate quickly (typically within less than ca. 4 ps), although the broken hydrogen bonds have a higher than average probability of reforming. Several aspects of the clustering of glycine molecules are investigated as a function of both temperature and concentration, including the size distribution of glycine clusters, the radii of gyration of the clusters, and aspects of the lifetimes of glycine-glycine hydrogen bonding by means of hydrogen-bond correlation functions. Diffusion coefficients for the glycine clusters and water molecules are also investigated and provide results in realistic agreement with experimental results.     

传感器用镓掺杂氧化锌纳米盘/纳米花状结构催化剂的制备及表面表征

采用简便的旋涂过程和一步水热法在压电基片上制备了Ga掺杂的ZnO纳米薄膜(GZO)。在水热处理过程中,通过添加不同的聚合物可形成纳米盘和纳米花状形貌的薄膜。采用场发射扫描电镜(Fe-SEM)、X射线衍射(XRD)和Raman光谱表征了样品的形貌、微结构和组成。 XRD和FE-SEM结果证明,在AlN/Si压电基片上形成的纳米盘、纳米棒和纳米花状GZO均为纤维锌矿相。采用浸渍法进一步在所制GZO样品上固定了绿色的荧光蛋白质(GFP)。运用原子力显微镜和荧光光谱分析了GFP与GZO表面结合的性质,考察了其用于传感器和生物成像技术的可行性。痕量GFP的固定使该材料产生荧光响应,表明其用于紫外光传感器时具有较好活性。