Stable sets and mean Li–Yorke chaos in positive entropy systems

It is shown that in a topological dynamical system with positive entropy, there is a measure-theoretically “rather big” set such that a multivariant version of mean Li–Yorke chaos happens on the closure of the stable or unstable set of any point from the set. It is also proved that the intersections of the sets of asymptotic tuples and mean Li–Yorke tuples with the set of topological entropy tuples are dense in the set of topological entropy tuples respectively.     

OCCUPATION TIME PROCESSES OF FLEMING-VIOT PROCESSES

ＯＣＣＵＰＡＴＩＯＮＴＩＭＥＰＲＯＣＥＳＳＥＳＯＦＦＬＥＭＩＮＧ－ＶＩＯＴＰＲＯＣＥＳＳＥＳ￥ＺＨＡＯＸＵＥＬＥＩ（ＩｎｓｔｉｔｕｔｅｏｆＭａｔｈｅｍａｔｉｃｓ，ＳｈａｎｔｏｕＵｎｉｖｅｒｓｉｔｙ，Ｓｈａｎｔｏｕ５１５０６３，Ｇｕａｎｇｄｏｎｇ，Ｃｈ...     

乙烷氧化脱氢制乙烯反应中制备方法及助剂对镍基催化剂性能的影响

采用不同方法制备了镍基催化剂,并考察了乙烷氧化脱氢制乙烯(ODE)的反应活性,结果表明,在3种不同制备方法的催化剂上,ODE反应的活性及产物选择性存在明显差异,浸渍法制备的催化剂性能最佳.在相同的条件下,以共浸渍法引入CeO2助剂后,N iO/-γA l2O3催化剂上的低温选择氧化活性显著提高,而目的产物C2H4的选择性变化不大.XRD,还原TG和XPS对催化剂进行表征的结果显示:反应的活性物相可能是易于还原的高度分散于催化剂表面的微晶N iO和表面尖晶石N iA l2O4物相;高分散的微晶N iO,类似于纯N iO,有利于ODE反应低温选择氧化生成目的产物C2H4,而易还原的表面尖晶石N iA l2O4物相的存在则可能是在高温下获得高选择氧化活性和选择性的主要原因之一.     

Transformation of inorganic sulfur into organic sulfur: a novel photoluminescent 3-D polymeric complex involving ligands in situ formation

The reaction of CuSCN with acetonitrile and methanol under solvothermal conditions yielded a novel 3-D polymeric photoluminescent complex containing dodecanuclear copper(I) clusters with methyl mercaptide. The synthesis involves in situ generation of ligands, which provides a model reaction to simulate the transformation of inorganic sulfur into organic sulfur under geothermic conditions.     

Effect of poly(hydroxybutyrate-co-hydroxyhexanoate) microparticles on growth of murine fibroblast L929 cells

Poly(hydroxybutyrate-co-hydroxyhexanoate) (PHBHHx) microparticles were successfully prepared and their proliferative effects on cultured fibroblasts were studied. PHBHHx microparticles (0.005-0.1 g/L) promoted cell proliferation in murine fibroblast L929 and elevated intracellular calcium concentrations ([Ca²⁺]_i). EGTA (ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid) inhibited PHBHHx microparticle-induced cell proliferation by chelating the extracellular Ca²⁺ and blocking the PHBHHx particle-induced [Ca²⁺]_i increase. Transwell experiments demonstrated that PHBHHx microparticles stimulated fibroblast proliferation when separated from cells by a 0.4 μm filter as effectively as when applied directly to cells. Since PHBHHx microparticles had a diameter of 75 μm, the stimulatory effect of PHBHHx particles on cell growth was attributed to degradation products smaller than 0.4 μm in diameter. The trophic effect of these microparticles is consistent with our previous reports demonstrating good biocompatibility for PHBHHx.     

Organocatalytic Enantioselective Synthesis of Axially Chiral N,N′-Bisindoles

This study establishes the first organocatalytic enantioselective synthesis of axially chiral N,N′-bisindoles via chiral phosphoric acid-catalyzed formal (3+2) cycloadditions of indole-based enaminones as novel platform molecules with 2,3-diketoesters, where de novo indole-ring formation is involved. Using this new strategy, various axially chiral N,N′-bisindoles were synthesized in good yields and with excellent enantioselectivities (up to 87 % yield and 96 % ee). More importantly, this class of axially chiral N,N′-bisindoles exhibited some degree of cytotoxicity toward cancer cells and was derived into axially chiral phosphine ligands with high catalytic activity. This study provides a new strategy for enantioselective synthesis of axially chiral N,N′-bisindoles using asymmetric organocatalysis and is the first to realize the applications of such scaffolds in medicinal chemistry and asymmetric catalysis.     

Insights into Electrochemical CO2 Reduction on SnS2: Main Product Switch from Hydrogen to Formate by Pulsed Potential Electrolysis

Tin disulfide (SnS₂) is a promising candidate for electrosynthesis of CO₂-to-formate while the low activity and selectivity remain a great challenge. Herein, we report the potentiostatic and pulsed potential CO₂RR performance of SnS₂ nanosheets (NSs) with tunable S-vacancy and exposure of Sn-atoms or S-atoms prepared controllably by calcination of SnS₂ at different temperatures under the H₂/Ar atmosphere. The catalytic activity of S-vacancy SnS₂ (V_s-SnS₂) is improved 1.8 times, but it exhibits an exclusive hydrogen evolution with about 100 % FE under all potentials investigated in the static conditions. The theoretical calculations reveal that the adsorption of *H on the V_s-SnS₂ surface is energetically more favorable than the carbonaceous intermediates, resulting in active site coverage that hinders the carbon intermediates from being adsorbed. Fortunately, the main product can be switched from hydrogen to formate by applying pulsed potential electrolysis benefiting from in situ formed partially oxidized SnS_2−x with the oxide phase selective to formate and the S-vacancy to hydrogen. This work highlights not only the V_s-SnS₂ NSs lead to exclusively H₂ formation, but also provides insights into the systematic design of highly selective CO₂ reduction catalysts reconstructed by pulsed potential electrolysis.     

Asymmetric (4+n) Cycloadditions of Indolyldimethanols for the Synthesis of Enantioenriched Indole-Fused Rings

Catalytic asymmetric construction of chiral indole-fused rings has become an important issue in the chemical community because of the significance of such scaffolds. In this work, we have accomplished the first catalytic asymmetric (4+2) and (4+3) cycloadditions of 2,3-indolyldimethanols by using indoles and 2-naphthols as suitable reaction partners under the catalysis of chiral phosphoric acids, constructing enantioenriched indole-fused six-membered and seven-membered rings in high yields with excellent enantioselectivities. In addition, this approach is used to realize the first enantioselective construction of challenging tetrahydroindolocarbazole scaffolds, which are found to show promising anticancer activity. More importantly, theoretical calculations of the reaction pathways and activation mode offer an in-depth understanding of this class of indolylmethanols. This work not only settles the challenges in realizing catalytic asymmetric cycloadditions of indolyldimethanols but also provides a powerful strategy for the construction of enantioenriched indole-fused rings.     

Classification of line-transitive point-imprimitive linear spaces with line size at most 12

In this paper we complete a classification of finite linear spaces with line size at most 12 admitting a line-transitive point-imprimitive subgroup of automorphisms. The examples are the Desarguesian projective planes of orders 4, 7, 9 and 11, two designs on 91 points with line size 6, and 467 designs on 729 points with line size 8.