Spirocyclisation of phytoalexin 1-methoxybrassinin in the presence of Grignard reagents

The anti-cancer properties of naturally occurring (2R, 3R)-(?)-1-methoxyspirobrassinol methyl ether (I) and their synthetic amino or piperidyl analogues II inspired us to study the synthesis of new target compounds III with a C—C bond in the 2-position of indole rather than a C—N or C—O bond (I or II respectively). The goal was achieved via electrophilic-nucleophilic 3,2-difunctionalisation of 1-methoxybrassinin (IV) in the presence of bromine and the Grignard reagent leading to the formation of cis- and trans-C—C analogues of I. Finally, the anti-cancer activities of the new compounds were measured and compared with I and II in order to show the importance of a heteroatom in the 2-substituted indole on the anti-cancer activity of spirobrassinols.     

Effect of Orientation on the Biodegradability of Aliphatic Copolyester Blown Films

The effects of process conditions on the orientation of aliphatic copolyester-blown films were investigated by using both Fourier transform infrared–attenuated total reflection (FTIR–ATR) dichroism and wide-angle X-ray diffraction (WAXD) methods. The results showed that a large increase in orientation was obtained by increasing the drawdown ratio (DDR). However, an unbalanced orientation was clearly shown at high DDR. A high blowup ratio was accompanied by reduced chain relaxation as well as fast crystallization, leading to more balanced films. The WAXD patterns of blown films exhibited the preferential orientation of lamellar crystallites. The results of microbial degradation indicated that the development of planar orientation evidently depressed biodegradability of samples. Video microscopy observations revealed that the degree of orientation played a dominant role in determining the rate of surface erosion. © 1997 John Wiley & Sons, Ltd.     

Arbitrarily vertex decomposable suns with few rays

A graph G of order n is called arbitrarily vertex decomposable if for each sequence (n₁,…,n_k) of positive integers with n₁+?+n_k=n, there exists a partition (V₁,…,V_k) of the vertex set of G such that V_i induces a connected subgraph of order n_i, for all i=1,…,k. A sun with r rays is a unicyclic graph obtained by adding r hanging edges to r distinct vertices of a cycle. We characterize all arbitrarily vertex decomposable suns with at most three rays. We also provide a list of all on-line arbitrarily vertex decomposable suns with any number of rays.     

Transport coefficients in high energy nuclear collisions

Starting from the Boltzmann equation for a fast test nucleon moving in the background medium provided by the other nucleons we derive an analytic expression for the transition kernel. From its first and second moments the friction and diffusion coefficients of a Fokker-Planck equation are obtained. These are compared with the results of a phenomenological transport model.     

Stereoselective synthesis and anticancer activity of broussonetine analogues

The stereoselective synthesis of two broussonetine analogues 14·HCl and ent-14·HCl with differing stereochemistry of the polyhydroxylated pyrrolidine core and a simple C₁₃ alkyl fragment has been achieved. For their construction, the known oxazolidinones 15 and 16 were chosen as appropriate advanced scaffolds. The common hydrophobic side chain was incorporated at an early stage of the synthesis through Grubbs’ cross metathesis chemistry. The required pyrrolidine skeleton was then formed by the cyclization of open chain intermediates 17 and 18. Four synthesized compounds were screened in vitro for antiproliferative/cytotoxic activity against six cancer cell lines by MTT assay. Compounds 14·HCl (HeLa and A-549) and ent-14·HCl (Caco-2 and Jurkat) showed comparable or higher potency than conventional anticancer agent cisplatin on at least two evaluated cancer cells, respectively.     

Organometallic Iridium(III) Complex Sensitized Ternary Hybrid Photocatalyst for CO2 to CO Conversion

A series of heteroleptic iridium(III) complexes functionalized with two phosphonic acid (−PO₃H₂) groups ( ^dfppy IrP , ^ppy IrP , ^btp IrP , and ^piq IrP ) were prepared and anchored onto rhenium(I) catalyst (ReP)-loaded TiO₂ particles (TiO₂/ReP) to build up a new IrP -sensitized TiO₂ photocatalyst system ( IrP /TiO₂/ReP). The photosensitizing behavior of the IrP series was examined within the IrP /TiO₂/ReP platform for the photocatalytic conversion of CO₂ into CO. The four IrP -based ternary hybrids showed increased conversion activity and durability than that of the corresponding homo- ( IrP +ReP) and heterogeneous ( IrP +TiO₂/ReP) mixed systems. Among the four IrP /TiO₂/ReP photocatalysts, the low-energy-light (>500 nm) activated ^piq IrP immobilized ternary system ( ^piq IrP /TiO₂/ReP) exhibited the most durable conversion activity, giving a turnover number of ≥730 for 170 h. A similar kinetic feature observed through time-resolved photoluminescence measurements of both ^btp IrP /TiO₂ and TiO₂-free ^btp IrP films suggests that the net electron flow in the ternary hybrid proceeds dominantly through a reductive quenching mechanism, unlike the oxidative quenching route of typical dye/TiO₂-based photolysis.     

The optimal general upper bound for the distinguishing index of infinite graphs

The distinguishing index $D\prime \left(G\right)$ of a graph $G$ is the least cardinal number $d$ such that $G$ has an edge-coloring with $d$ colors, which is preserved only by the trivial automorphism. We prove a general upper bound $D\prime \text{◂≤▸}\left(G\right)\le \mathrm{\Delta }-1$ for any connected infinite graph $G$ with finite maximum degree $\mathrm{\Delta }\ge 3$. This is in contrast with finite graphs since for every $\mathrm{\Delta }\ge 3$ there exist infinitely many connected, finite graphs $G$ with $\text{◂,▸}D\prime \left(G\right)=\mathrm{\Delta }$. We also give examples showing that this bound is sharp for any maximum degree $\mathrm{\Delta }$.     

Synthesis of methyl 2-aryl-5-chlorosulfonyl-1,3-oxazole-4-carboxylates and their reactions with amines and amidines

Previously unknown methyl 2-aryl-5-chlorosulfonyl-1,3-oxazole-4-carboxylates have been synthesized. Their reactions with amines and amidines have yielded the corresponding sulfonamides and 6H,7H-[1,3]oxazolo-[5,4-d]pyrimidin-7-ones.     

Fabrication and optical characterization of p-type single macro-porous silicon for detection of nano-sized functionalized superparamagnetic beads

Porous silicon (PSi) shows tremendous potential for applications including optical devices and biochemical biosensors due to the large surface area and convenience of surface functionalization of pores. Recently, variations of the Fabry–Pérot fringes shift with the refractive index of the material filling the pores of PSi have been used for real time monitoring of biorecognition processes, where the optical shift is determined by the magnitude of the optical thickness (2nL) by fast Fourier transform (FFT). The development of biosensing systems using functionalized superparamagnetic beads (SPBs) or ‘magnetic labels’ is expected to enable a fast, one-step immunoassay protocol. However, magnetic labels are difficult to infiltrate into small nanopores in silicon due to blocking effects such as surface tension, wettability, and stomatal morphology. Here, we investigated the optimal fabrication parameters of PSi with large pores into which magnetic labels easily infiltrate, and confirmed the penetration of SPBs by the changes in the optical thickness 2nL by reflectivity measurements. Finally, we show the potential for real-time point of care diagnostic system by utilizing our method.