A relationship between correlation energies and sizes: The helium-like ions

The correlation energy (E _corr) is found to be inversely proportional to the product of the electron pair size (2>) and the square of the effective nuclear charge (Z _eff) for the helium-like ions.     

Self-dual embeddings of Cayley graphs

A method for constructing both orientable and non-orientable embeddings of Cayley graphs is described. This method yields all the previously known constructions in addition to producing some new self-dual embeddings.     

Genus embeddings for some complete tripartite graphs

The voltage graph construction of Gross is extended to the case where the base graph is non-orientably embedded. An easily applied criterion is established for determining the orientability character of the derived embedding. These methods are then applied to derive both orientable and non-orientable genus embeddings for some families of complete tripartite graphs.     

Sulfures et disulfures : acidités cinétiques relatives des protons adjacents au soufre

Dibenzyl disulfide is deprotonated at ?78° approximately 7.5 times more rapidly than dibenzyl sulfide, as predicted by a molecular orbital analysis which focuses on the interaction between the carbon lone pair and an adjacent σ * orbital.     

Critique of a Materialist Analysis of Operational Research

In a 1982 paper, Rosenhead and Thunhurst analysed the origins, development and current practice of operational research from an historical and materialist perspective. A critique of the theoretical and practical implications of their arguments is presented in this paper, along with an alternative interpretation of the historical facts. The relationship between operational research and the forces affecting the development of the capitalist society are discussed within this context.     

Preparation and Investigation of Thermally Annealed Zein–Propolis Electrospun Nanofibers for Biomedical Applications

Zein, a corn-derived protein, has a variety of applications ranging from drug delivery to tissue engineering and wound healing. This work aims to develop a biocompatible scaffold for dermal applications based on thermally annealed electrospun propolis-loaded zein nanofibers. Pristine fibers' biocompatibility is determined in vitro. Next, propolis from Melipona quadrifasciata is added to the fibers at different concentrations (5% to 25%), and the scaffolds are studied. The physicochemical properties of zein/propolis precursor dispersions are evaluated and the results are correlated to the fibers' properties. Due to zein's and propolis' very favorable interactions, which are responsible for the increase in the dispersions surface tension, nanometric size ribbon-like fibers ranging from 420 to 575 nm are obtained. The fiber's hydrophobicity is not dependent on propolis concentration and increases with the annealing procedure. Propolis inhibitory concentration (IC₅₀) is determined as 61.78 µg mL⁻¹. When loaded into fibers, propolis is gradually delivered to cells as Balb/3T3 fibroblasts and are able to adhere, grow, and interact with pristine and propolis-loaded fibers, and cytotoxicity is not observed. Therefore, the zein–propolis nanofibers are considered biocompatible and safe. The results are promising and provide prospects for the development of wound-healing nanofiber patches—one of propolis' main applications.     

On the structures of alpha-lithiated sulfoxide,sulfone and sulfonium systems. Implications for the stereochemistry of functionalization of carbon atoms adjacent to sulfur

The fully optimized geometries of C-S torsional isomers of LiCH₂SHO, LiCH₂SHO₂, and LiCH₂SH₂⁺ have been computed at the 3–21G^* level. The global minima of the sulfoxide and sulfone contain intramolecular LiO bonds. In the presence of Li⁺, intermolecular LiO bonding alters the structure of the alpha-lithiated sulfoxide, and the CLi bond is antiperiplanar to oxygen. The alpha-lithiated sulfonium cation exhibits no unusual conformational features, and a low barrier to CS torsion. The implications of these results upon the stereochemistry of functionalization of a carbon atom adjacent to sulfur by a lithiation-quenching sequence are discussed.