Lugdunomycin,an Angucycline‐Derived Molecule with Unprecedented Chemical Architecture

The angucyclines form the largest family of polycyclic aromatic polyketides, and have been studied extensively. Herein, we report the discovery of lugdunomycin, an angucycline‐derived polyketide, produced by Streptomyces species QL37. Lugdunomycin has unique structural characteristics, including a heptacyclic ring system, a spiroatom, two all‐carbon stereocenters, and a benzaza‐[4,3,3]propellane motif. Considering the structural novelty, we propose that lugdunomycin represents a novel subclass of aromatic polyketides. Metabolomics, combined with MS‐based molecular networking analysis of Streptomyces sp. QL37, elucidated 24 other rearranged and non‐rearranged angucyclines, 11 of which were previously undescribed. A biosynthetic route for the lugdunomycin and limamycins is also proposed. This work demonstrates that revisiting well‐known compound families and their producer strains still is a promising approach for drug discovery.     

Validation of analytical method for furan determination in eight food matrices and its levels in various foods

In this study, an automated solid‐phase microextraction coupled with gas chromatography and mass spectrometry method was developed and validated for the determination of furan in eight matrices including ham, milk, apple juice, rice porridge, peanut butter, flatfish, tuna (canned) and seaweed. The calibration curves were highly linear (r² > 0.990) and the limit of detection and limit of quantification ranged from 0.01?0.02 and 0.04?0.06 ng/g, respectively. The recovery ranged from 77.81?111.47%. The validated method was used to analyse the furan levels in 120 foods. The highest levels of furan were detected in black tea (172.05 ng/g) and red ginseng extract (89.27 ng/g). Whelk (canned) contained a high furan content (21.34 ng/g) among the seafood samples.     

Single-body lensed photonic crystal fibers as side-viewing probes for optical imaging systems

We report the fabrication and performance of a lensed photonic crystal fiber (PCF) designed as a compact but effective side-viewing optical imaging probe. The lensed-PCF probe was implemented in a single body without using any other fibers or additional optics. The beam expansion region and a focusing ball lens, necessary for a focuser, were simultaneously formed along a small piece of PCF by applying arc discharges. The side-viewing ability was provided by polishing the ball lens with a femtosecond laser to form a total internal reflection surface. The working distance and the transverse resolution of the fabricated single-body lensed-PCF were experimentally measured to be 570 and 6.8 microm, respectively. With the proposed lensed-PCF probe, optical coherence tomography images of an in vitro biological sample were successfully obtained.     

Polybenzimidazoles for High Temperature Fuel Cell Applications

Summary: Fuel cells were designed for high temperature operations. Poly[2,2′‐(m‐phenylene)‐5,5′‐bibenzimidazole] (PBI) was synthesized in a solution of P₂O₅, CH₃SO₃H, and CF₃SO₃H. The PBI was dissolved in a mixture of CF₃CO₂H and H₃PO₄ and the solution was used for the preparation of Pt catalyst slurry for membrane electrode assembly. The single cell showed a current density of 280 mA · cm⁻² at a cell voltage of 0.5 V with feeds of H₂ and O₂ at 160 °C and without external humidification.

     

Study on the vertical alignment of nematic liquid crystals by fumed silica doping

The alignment of liquid crystals is important in the manufacturing of devices. Usually, the alignment layer is prepared using a thin-film coating, thermal processing and processes such as rubbing or photo-alignment. Several trials without processes related to the alignment layer were performed for realizing vertical alignment. The main approaches were to utilize the self-assembly of the alignment agent on the substrate. Here, tiny amount of fumed silica, a kind of nano-particle, was added to nematic liquid crystals. With a low frequency electric field and thermal treatment, the region of vertical alignment was obtained. In addition, the efficiency of alignment was related to the polarity of the electric field. The vertical alignment by the fumed silica was active for negative polarity. This results in an easy and convenient way of obtaining vertical alignment.     

Novel desulfurization of thiocarbonyl compounds into their corresponding oxo-derivatives using a peroxy-sulfur intermediate generated from 2-nitrobenzenesulfonyl chloride and superoxide anion.

Thiocarbonyl compounds such as substituted-thioureas, -thioamides and -thiocarbamates were found to react with a peroxysulfur intermediate (3) which is generated by the treatment of 2-nitrobenzenesulfonyl chloride with potassium superoxide to convert into the corresponding carbonyl compounds in quantitative yield at ?30°C in acetonitrile.     

Partial miscibility in multicomponent polymer system

It has been shown, using the significant structure theory of liquids, that a lower critical solution temperature behavior as well as a upper critical solution temperature behavior can be expected for polymer–polymer systems and that a phase diagram of closed-loop-type in a polymer–polymer–solvent system can be possible. In this article the sublimation energy of a mixture was expressed as a quadratic form of segment surface fractions on pure components rather than that of mole fractions, and the effect of the segment surface fractions on critical compositions was explained. The calculated partial miscibilities were in good agreement with the experiment.     

High performance liquid chromatography-electrospray lonization MS-MS analysis ofForsythia koreana fruits, leaves, and stems. Enhancement of the efficiency of extraction of arctigenin by use of supercritical-fluid extraction

Summary A method involving high-performance liquid chromatography coupled with electrospray MS-MS has been developed for the analysis of the constituents of the fruits, leaves, and stems ofForsythia koreana. Ten compounds including caffeoyl glycosides and lignans could be separated and detected with good sensitivity. The MS-MS spectra obtained provided information about their structures, for example the sugar and aglycone moieties present. Supercritical-fluid extraction was also used to improve the efficiency of extraction of arctigenin, which has the highest anti-inflammatory activity of the compounds produced by this plant. Although carbon dioxide without any modifier extracted only 66% of that obtained by extraction with methanol, an 80:20 (v/v) carbon dioxide-methanol mixture greatly enhanced the extraction yield-to 110%.