Near nearfield planes

The translation planes of order k that admit at least two affine homology groups of order (k–1)/2 are classified. If k7² or 23², the plane is generalized André and there is a Dickson pair {q, n} such that q ⁿ =k and a cyclic homology subgroup of order (q ⁿ –1)/2n.This article was written when the first author was visiting the University of Iowa during 1990–91.     

Peroxide-catalyzed grafting of maleic anhydride onto molten polyethylene in the presence of polar organic compounds

The crosslinking of LDPE resulting from reaction with dicumyl peroxide at 180°C is increased in the presence of maleic anhydride (MAH). The presence of electron-donating nitrogen-containing compounds (amides, lactams, disubstituted aromatic amines, and amine oxides), phosphorous-containing compounds (phosphites, phosphates, phosphonates, phosphoramides, and phosphine oxides) and sulfur-containing compounds (sulfoxides, aryl disulfides, and thiazyl disulfides) which inhibit the homopolymerization of MAH but not that of methyl methacrylate, prevents crosslinking and yields soluble PE containing MAH units. Crosslinking, due to coupling of PE^˙ macroradicals formed by hydrogen abstraction from PE by excited MAH, is prevented by electron donation from the additive to the MAH⁺ cation which is present in the MAH+?MAH excimer as well as in the excimer which is appended to the PE.     

Chloro­bis­(tri­phenyl­phosphine)­nickel(I)

Crystals of the title compound, [NiCl(C₁₈H₁₅P)₂], contain one mol­ecule per asymmetric unit with no short intermolecular interactions. This is noteworthy since previous studies have reported that the formally 15‐electron species oligomerizes in the solid state. The nickel(I) centre has a distorted trigonal–planar coordination geometry, the origin of which is suggested to be electronic in nature.     

Electronic Energy Spectrum of Two-Dimensional Solids and a Chain of C Atoms from a Quantum Network Model

The aim of this study is to explain how a quantum network can be used as simple model to calculate complex band structures. The paper contains an introduction, a mathematical exposure of the method, and applications to graphene, boron nitride, and polyacetylene chains. Using a quantum network is a simple, intuitive, and, yet, rather accurate way to obtain a band structure for a complex material. One focus here is to invoke physical and chemical intuition to construct the effective one-body potential along the wires of a quantum network.     

Pentacyclic Triterpene Profile and Its Biosynthetic Pathway in Cecropia telenitida as a Prospective Dietary Supplement

Promising research over the past decades has shown that some types of pentacyclic triterpenes (PTs) are associated with the prevention of type 2 diabetes (T2D), especially those found in foods. The most abundant edible sources of PTs are those belonging to the ursane and oleanane scaffold. The principal finding is that Cecropia telenitida contains abundant oleanane and ursane PT types with similar oxygenation patterns to those found in food matrices. We studied the compositional profile of a rich PT fraction (DE16-R) and carried out a viability test over different cell lines. The biosynthetic pathway connected to the isolated PTs in C. telenitida offers a specific medicinal benefit related to the modulation of T2D. This current study suggests that this plant can assemble isobaric, positional isomers or epimeric PT. Ursane or oleanane scaffolds with the same oxygenation pattern are always shared by the PTs in C. telenitida, as demonstrated by its biosynthetic pathway. Local communities have long used this plant in traditional medicine, and humans have consumed ursane and oleanane PTs in fruits since ancient times, two key points we believe useful in considering the medicinal benefits of C. telenitida and explaining how a group of molecules sharing a closely related scaffold can express effectiveness.