Riddled basins are shown to occur in a simple mechanical device consisting of masses and springs. Convergence probabilities versus deviations in the initial conditions are quantified by three independent methods, all leading to scale-invariance over many decades. Conditions exist for the occurrence of two-state on-off intermittency involving switching between predictable and unpredictable oscillations. 相似文献
Highly efficient formation of poly(propylene carbonate) can be achieved in the coupling of CO2 and propylene oxide assisted by 4‐(N,N‐dimethylamino)pyridine (DMAP) and catalyzed with salen chromium(III) chloride by using DMAP/Cr ratios of less than 2. Under these conditions a possible backbiting mechanism is suppressed, leading to only minor amounts of cyclic carbonate as a side product.
The polycondensation of tryptophan N‐carboxyanhydride (NCA‐Trp) is investigated in the presence and in the absence of POPC (1‐O‐palmitoyl‐2‐O‐oleoyl‐sn‐glycerol‐3‐O‐phosphocholine) liposomes with the aim to study and to quantify possible stereoselective effects of the process. A novel technique, based on isotope labeling of one enantiomer, and high performance liquid chromatography mass spectrometry (LC‐MS) allow determination of the individual stereoisomer distribution of oligomers up to n=10. For the first time, the preferential homochiral growth and the relative stereoisomer distributions for each oligomer length are directly demonstrated. 相似文献
Synthesis and Structures of the Gold Cluster [Au16(AsPh3)8Cl6] Reduction of Ph3AsAuCl with NaBH4 in ethanol yields the gold cluster [Au16(AsPh3)8Cl6]. It can be crystallized from dichloromethane/diisopropyl ether in form of dark red, light sensitive crystals with the space group P21/n and a = 1777.68(8), b = 3372.7(1), c = 2696.2(1)pm, β = 94.166(6)°, Z = 4). The inner skeleton of the 16 Au atoms consists of a centered icosahedron of which one of the corners binds to three additional Au atoms forming a tetrahedron pendent. The shortest Au–Au distances of 264.3 to 266.6 pm correspond to the bonds to the three external Au atoms. Within the icosahedron the distances between the central atom and the peripheral atoms (273.0–279.1 pm) are distinctly shorter than the distances between the peripheral atoms (283.6–299.0 pm). 相似文献
The single‐crystal X‐ray structure analysis of hexakis(2,4,6‐triisopropylphenyl)cyclotristannoxane, cyclo‐[(2,4,6‐i‐Pr3‐C6H2)2SnO]3 ( 1 ), is reported and reveals this compound to contain an almost planar six‐membered ring. Redistribution reactions of 1 with cyclo‐(t‐Bu2SnO)3 and t‐Bu2SiCl2, respectively, failed and indicate an unusual kinetic inertness of the Sn–O bonds in 1 as compared to related molecular diorganotin oxides containing less bulkier substituents. The redistribution reaction of cyclo‐(t‐Bu2SnO)3 with cyclo‐(t‐Bu2SnS)2 leads to an equilibrium involving the trimeric diorganotin oxysulphides cyclo‐t‐Bu2Sn(OSnt‐Bu2)2S ( 2 a ) and cyclo‐t‐Bu2Sn(SSnt‐Bu2)2O ( 2 b ). 相似文献