Iodo–sesquiterpene hydroquinone and brominated indole alkaloids from the Thai sponge Smenospongia sp.

6′-Iodoaureol, an iodo–sesquiterpene hydroquinone, 6′-aureoxyaureol, a bissesquiterpene hydroquinone, and four brominated indole alkaloids 3–6 were isolated from the Thai sponge Smenospongia sp. Additionally, four known sesquiterpene hydroquinones 12–15, ten known brominated indole alkaloids 7–11, 17–18, and 20–22, ergosterol, and furospinosulin-1 were also isolated. Compound 1 is the first reported iodo–sesquiterpene hydroquinone and compounds 7–11 were isolated for the first time from natural sources. The structures were characterized by spectroscopic analyses as well as comparison with literature data. Several of these metabolites were evaluated for cytotoxic activity against seven tumor cell lines.     

Recycling of mixed automotive plastics

Mixed plastics from junked autos were homogenized by milling or extrusion, modified by addition of low-molecular-weight low-melt-viscosity polymers, and processed by compression or injection molding. Properties were comparable with high-density polyethylene and common building panel materials.     

Factors affecting orthogonality in the deprotection of 2,4-di-protected aromatic ethers employing solid-supported acids

Selective deprotection of aromatic ethers bearing two protecting groups on the same aromatic ring by solid-supported acids (Amberlyst-15 and PTS-Si) was systematically investigated. ortho-Directing protonation by the carbonyl group as well as carbocation stability and quenching are the important determining factors for the orthogonal deprotection process. Stablilized carbocations (e.g., those from the MOM and PMB groups) could be removed with high selectivity.     

A new cytotoxic daphnane diterpenoid, rediocide G, from Trigonostemon reidioides

Rediocide G (7), a new daphnane diterpenoid, was isolated from the roots of Trigonostemon reidioides (Euphorbiaceae), together with two congeners, rediocide A and rediocide B, (+)-syringaresinol, scopoletin, tomentin and stigmasterol. The structure of the new natural product was elucidated by comparison of its NMR and mass spectral data with those of previously known rediocides and confirmed by extensive 2D NMR spectral analysis. Rediocide G (7) was found to be cytotoxic to various cancer cell lines.     

Radical-Mediated Halogenations of Anomerically N-Substituted Glucopyranosyl Derivatives

Abstract

Reactions of acetylated N-aryl-D-glucosylamines with N-bromosuccinimide-benzoyl peroxide or with sulfuryl chloride-azoisobutyronitrile gave aromatic halo derivatives. The corresponding N-acetylated compounds were mostly inert towards halogenation. Bromination of acetylated cellobiosylpiperidine resulted in the formation of acetobromocellobiose, while the acetylated 2,6,8-trichloro-9-(β-D-glucopyranosyl)-purine was transformed into its 5′-bromo derivative. In contrast, peracetylated glucopyranosyl isothiocyanate or azides, when treated by N-bromosuccinimide under free-radical conditions, essentially undergo an initial homolysis of the anomeric C-H bond which is faster for β-anomers. This initiates a new, simple and efficient free-radical transformation of such sugar azides into an unprecedented brornimino lactone (92% isolated yield).     

Dynamics of elastic bodies connected by a thin soft viscoelastic layer

A dynamic study was performed on a structure consisting of two three-dimensional linearly elastic bodies connected by a thin soft nonlinear Kelvin–Voigt viscoelastic adhesive layer. The adhesive is assumed to be viscoelastic of Kelvin–Voigt generalized type, which makes it possible to deal with a relatively wide range of physical behavior by choosing suitable dissipation potentials. In the static and purely elastic case, convergence results when geometrical and mechanical parameters tend to zero have already been obtained using variational convergence methods. To obtain convergence results in the dynamic case, the main tool, as in the quasistatic case, is a nonlinear version of Trotter?s theory of approximation of semigroups acting on variable Hilbert spaces. The limit problem involves a mechanical constraint imposed along the surface to which the layer shrinks. The meaning of this limit with respect to the relative behavior of the parameters is discussed. The problem applies in particular to wave phenomena in bonded domains.     

Optical spin generated by a soliton pulse in an add–drop filter for optoelectronic and spintronic use

A new concept of an optical spin generation using bright and dark soliton conversion behaviors within a modified optical add–drop filter known as PANDA ring resonator is proposed. The orthogonal solitons can be formed within the system and detected simultaneously at the output ports. Under the resonant condition, the dark and bright soliton pair corresponding to the left-hand and right-hand rotating solitons (photons) can be generated. When a soliton is absorbed by an object, an angular momentum of either +? or ?? is imparted to the object, in which two possible spin states known as optoelectronic(soliton) spins are exhibited. Furthermore, an array of soliton spins, i.e. particles can be generated and detected by the proposed system, which can be used to form large scale spin generation.