Novel design of a pentacyclic scaffold as structural mimic of saframycin A

The design, synthesis and evaluation of a pentacyclic scaffold, CWO-324 to mimic saframycin A is described. CWO-324 is readily synthesized in five steps from 1,4-diacetyl-piperazine-2,5-dione and 2,5-dimethoxybenzaldehyde. CWO-324 was found to scission DNA, binds to bases 69-83(5′-GCAGTCAGG CACCGT-3′) of Hind III/Rsa I from plasmid pBR322 DNA in a foot-printing study and possesses anti-tumor activity.     

Gas-phase complexation of polyethers with halide ions

Gas-phase complexes of halide anions with a variety of crown ethers and acyclic analogs are formed by ion-molecule reactions in the chemical ionization source of a triple-quadrupole mass spectrometer. The ether complexes of iodide, bromide, and chloride dissociate on collisional activation by cleavage of the halide-ether electrostatic hydrogen bonds, resulting in the formation of bare halide anions. By contrast, the fluoride complexes dissociate by loss of HF, which may occur in conjunction or sequentially with losses of ethylene oxide units. This dissociation behavior is similar to that observed for collisionally activated dissociation of [M ? H]^? ions of the crown ethers and suggests that the fluoride ion is capable of promoting an intramolecular proton abstraction within the [M+F]^? complex. This type of dissociation chemistry is only observed for the fluoride ion complexes, and the fluoride ion is the most basic of all the halides. The kinetic method was used to establish orders of relative halide binding strengths, and the trends for the chloride and bromide affinities were 12-crown-4 < triethylene glycol dimethyl ether < 15-crown-5 < tetraethylene glycol dimethyl ether < 18-crown-6 < 21-crown-7 < tetraethylene glycol < pentaethylene glycol < 1,4,7,10,13-pentathiacyclopentadecane.     

Reconfigurable WDM add/drop multiplexer based on optical switches and fibre Bragg gratings

A reconfigurable wavelength-division-multiplexing (WDM) add/drop multiplexer (WADM) is constructed using optical switches (OSWS) and fibre Bragg gratings (FBGs). Selected one or two channel(s) can be added/dropped at the same multiplexer by properly controlling the optical switch pair and fibre Bragg grating arrangement. Afour-channel system is experimentally demonstrated for a data rate of 2.5 Gb s–1 and a single-mode fibre (SMF) distance of 100km. A negligible maximum power penalty of only 0.3dB is observed when compared with back-to-back transmission.     

Compatibility and characteristics of poly(butylene succinate) and propylene-co-ethylene copolymer blend

Propylene-co-ethylene elastomer resin (PER) has been blended into biodegradable poly(butylene succinate) copolymer (PBS) by a melt-blending process to develop a novel semi-biodegradable thermoplastic elastomer. The PBS/PER blends displayed good compatibility in the range 70/30 > PBS/PER > 30/70 according to analyses by DSC, DMA and the Couchman method. Although the PBS/PER blends displayed compatibility, SEM analyses of most of the PBS/PER blends revealed two-phase structures including sea-island and irregular fiber-shaped morphologies, except for PBS/PER (70/30). PBS/PER (60/40) and PBS/PER (50/50) display low tensile strength due to large sea-phase and irregular fiber-shaped morphologies, even though they have good compatibility. PBS/PER (70/30) apparently exhibited a single phase by SEM and showed the best compatibility by DSC and DMA. Furthermore, the tan δ, elongation and initial moduli of the PBS/PER blends were seen to increase with increasing PER content, indicating that the toughness and shock resistance of PBS are improved by incorporating PER into the composition.     

Fabrication of optical reflectors by using of elastomer with self-organized undulations

Back-surface diffusive reflectors have been widely applied in many optical systems to promote the efficiency used in system. In this work, we propose a novel way to fabricate a soft diffusive reflector by using of silicone (polydimethylsiloxane, PDMS). High-reflectance substrates were first fabricated by mixing nanoscaled TiO₂ powders with PDMS polymers, and then microscale wave-like undulations were spontaneously developed after the substrates were dipped into H₂SO₄/HNO₃ solutions. After optical examination, a TiO₂/PDMS plate comprising microscale undulations, which can surely serve as a reflector, could reflect and diffuse light effectively. Besides, all fabrication processes can be executed in the ambient environment and at low temperature. This proposed method has a potential for mass production in the future.     

PEG–Anthracene Hydrogels as an On‐Demand Stiffening Matrix To Study Mechanobiology

There is a growing interest in materials that can dynamically change their properties in the presence of cells to study mechanobiology. Herein, we exploit the 365 nm light mediated [4+4] photodimerization of anthracene groups to develop cytocompatible PEG‐based hydrogels with tailorable initial moduli that can be further stiffened. A hydrogel formulation that can stiffen from 10 to 50 kPa, corresponding to the stiffness of a healthy and fibrotic heart, respectively, was prepared. This system was used to monitor the stiffness‐dependent localization of NFAT, a downstream target of intracellular calcium signaling using a reporter in live cardiac fibroblasts (CFbs). NFAT translocates to the nucleus of CFbs on stiffening hydrogels within 6 h, whereas it remains cytoplasmic when the CFbs are cultured on either 10 or 50 kPa static hydrogels. This finding demonstrates how dynamic changes in the mechanical properties of a material can reveal the kinetics of mechanoresponsive cell signaling pathways that may otherwise be missed in cells cultured on static substrates.     

Combination of electrochemistry and the concurrent reduction and substitution chemistry to provide a facile and versatile tool for preparing functional polyanilines

Polyaniline as the first commercially available conducting polymer has recently received great attention from both academic and industrial communities. Although there have been quite a few reports on substituted polyanilines, none of them are concerning about the amino- and alkylthio-substituted polyanilines. Unlike other substituted polyanilines, the attempts in synthesizing poly(alkylthioaniline) directly from the alkylthioaniline monomer via chemical and electrochemical oxidative-coupling chemistry were all fail. On the other hand,we have recently discovered that the amino and alkylthio functional groups can be easily introduced to the backbone of emeraldine polyaniline via the concurrent reduction and substitution chemistry. Further combination of electrochemistry and the concurrent reduction and substitution chemistry can provide us a facile and versatile tool for preparing functional polyanilines. Different functional groups can be introduced sequentially to the same polymer backbone. The concentrations of each substituents can be easily controlled. This new process provides us a useful utility for tailoring the molecular and the electronic structures of polyanilines to render them with appropriate and possibly new material properties suitable for many different potential applications.     

A New CoII Complex as a Bulge-Specific Probe for DNA

Bulge cleavage of two or three bases occurs when a DNA substrate is specifically cleaved oxidatively by [Co^II(tfa)₂(happ)] (see picture). Hydrogen peroxide is necessary for the activation of this octahedral complex, which suggests that hydroxyl radicals are the reactive species. The complex has no significant reactivity towards the corresponding sequence in a single-stranded DNA region, and it exhibits only a low affinity towards double-stranded DNA. happ=macrocyclic ligand based on 1,10-phenanthroline, tfa=trifluoroacetate.