Antioxidant properties of herbal extracts selected from screening for potent scavenging activity against superoxide anions

BACKGROUND: In a previous study with the electron spin resonance (ESR) spin‐trapping method on large‐scale screening with ethanol extracts of approximately 1000 kinds of herbs, four herbal extracts with prominently potent ability to scavenge superoxide anions were chosen, namely the extracts from Punica granatum (peel), Syzygium aromaticum (bud), Mangifera indica (kernel) and Phyllanthus emblica (fruit)). In the present study, these extracts were further examined to determine if they also scavenge hydroxyl radicals, by applying the ESR spin‐trapping method, and if they have heat resistance as a desirable characteristic feature. RESULTS: Experiments with the Fenton reaction and UV irradiation of hydrogen peroxide, both of which generate hydroxyl radicals, showed that all four extracts had potent ability to directly scavenge hydroxyl radicals. Each extract exerted more potent hydroxyl radical‐scavenging activity than mannitol and salicylic acid. Furthermore, the scavenging activities against superoxide anions and hydroxyl radicals of the extracts of P. granatum (peel), M. indica (kernel) and P. emblica (fruit) proved to be heat‐resistant. CONCLUSION: The four herbal extracts chosen from extensive screening possess desirable antioxidant properties. In particular, three of them are expected to be suitable for food processing in which thermal devices are used, because of their heat resistance. Copyright © 2008 Society of Chemical Industry     

Design of novel efficient sensitizing dye for nanocrystalline solar cell; tripyridine-thiolato (4,,-tricarboxy-2,:,-terpyridine)ruthenium(II)

We have designed tripyridine-thiolato (4,4^′,4^″-tricarboxy-2,2^′:6^′,2^″-terpyridine)ruthenium(II) [complex 1], a novel efficient sensitizing dye for dye sensitized TiO₂ solar cells, based on the DFT MO calculations with PBE0 functional. Complex 1 is a modified BD (black dye: trithiocyanato (4,4^′,4^″-tricarboxy-2,2^′:6^′,2^″-terpyridine)ruthenium(II) complex) molecule where NCS ligands of BD are replaced by C₅H₄NS ligands. Molecular and electronic structures of complex 1 have been theoretically characterized. Complex 1 is expected to have the following two advantages over BD, in addition to the advantage of high electron transfer rate from the photoexcited dye to TiO₂ realized in BD: (1) higher electron transfer rate from redox systems to oxidized dyes; (2) higher absorption efficiency to solar spectrum. We propose complex 1 as a novel efficient sensitizing dye which provides the higher efficiency than does BD for dye sensitized solar cells.     

Design and Synthesis of Fluoro Analogues of Vitamin D

The discovery of a large variety of functions of vitamin D₃ and its metabolites has led to the design and synthesis of a vast amount of vitamin D₃ analogues in order to increase the potency and reduce toxicity. The introduction of highly electronegative fluorine atom(s) into vitamin D₃ skeletons alters their physical and chemical properties. To date, many fluorinated vitamin D₃ analogues have been designed and synthesized. This review summarizes the molecular structures of fluoro-containing vitamin D₃ analogues and their synthetic methodologies.     

Hydrothermal Wave Instability in a High-Aspect-Ratio Liquid Bridge of Pr > 200

The long-duration fluid physics experiments on a thermocapillary-driven flow have been carried out on the Japanese Experiment Module ‘Kibo’ aboard the International Space Station (ISS) since 2008. In these experiments, various aspects of thermocapillary convection in a half-zone (HZ) liquid bridge of high Prandtl number fluid have been examined under the advantages of the long-duration high-quality microgravity environment. In 2010, the authors succeeded to realize nonlinear convective fields in the HZ liquid bridge of rather high aspect ratio. Special attention was paid on to the complex convective fields, especially on the behaviors of the hydrothermal wave (HTW) over the free surface visualized by an infrared camera. In order to evaluate the characteristics of the nonlinear convective behaviors and their transition processes, the authors indicate the images taken by the infrared camera describing the time evolution of HTW, the spatio-temporal diagram, the Fourier analysis, and the pseudo-phase space, reconstructed from the time series of the scalar information of the liquid bridge, that is, surface temperature variation. In this paper, the authors introduce the signature of complex HTW behaviors observed at the long-duration on-orbit experiments, and make comparisons with some previous terrestrial and microgravity experiments.     

LCST phase separation and thermoreversible gelation in aqueous solutions of stereo-controlled poly(N-isopropylacrylamide)s

Stereoregular poly(N-isopropylacrylamide)s with controlled content of isotactic dyads have recently been synthesized, and interesting interference phenomena between LCST phase separation and high-temperature reversible gelation have been observed in their aqueous solutions. We develop a model solution in which dehydrated stereo-regular isotactic segments on polymers are driven into intermolecular cross-links leading to gelation. We theoretically calculate the phase diagrams for the varied content isotactic dyads and compare with the experimental data.     

Generating 1-DOF limit cycle walking at target walking speed by feed-forward and feedback limit cycle control

We propose the feed-forward and feedback (FaF) control systems for generating the limit cycle walking at a target walking speed by the combined rimless wheel (CRW) model. The proposed FaF control systems can calculate a control input constantly based on the mathematical analysis of the current and target walking states. As a result, first, the limit cycle walking at the target walking speed is generated by numerical simulations when the walker is driven by the constant FaF control system. Second, for controlling the convergence speed, we extend the FaF control to the two-period stepwise control systems. The limit cycle walking at the target walking speed is still generated, and the convergence speed is controlled by the settling time parameter. Finally, the real-time walking state updating is considered in the FaF control systems to handle the disturbances. In this case, we find that for generating a target walking speed, a precise mathematical model is not necessary for generating the target state, but can make the control input stable and efficient.     

Total synthesis of zoanthamine alkaloids

Zoanthamine alkaloids, isolated from organisms in the Zoanthus genus, constitute a distinctive family of marine metabolites. These molecules exhibit a broad spectrum of unique biological properties. For example, norzoanthamine inhibits interleukin-6, the key mediator of bone resorption in osteoporosis, providing a promising drug candidate for a disease that affects more than 10 million people over age 50 in the United States. In addition, these natural products are characterized by a densely functionalized heptacyclic framework, as exemplified by the structures of zoanthamine, norzoanthamine, and zoanthenol, which makes them extremely attractive targets for chemical synthesis. Prior to our first total synthesis of norzoanthamine in 2004, the densely functionalized and complex stereostructures of the zoanthamine alkaloids had impeded synthetic studies of these molecules. In this Account, we describe our synthetic approach toward the total synthesis of zoanthamine alkaloids, focusing on how we overcame various synthetic challenges. At the beginning of our synthetic studies, we aimed to develop an efficient route that was flexible enough to provide access to several members of the family while allowing the synthesis of various analogues for biological testing. Our first project was the total synthesis of norzoanthamine, and we established an efficient synthetic route based on a novel strategy involving the following key features. First, we used a sequential three-component coupling reactions and subsequent photosensitized oxidation of a furan moiety to synthesize the precursor for the key intramolecular Diels-Alder reaction. Second, the key intramolecular Diels-Alder reaction constructed the ABC-ring carbon framework bearing two adjacent quaternary asymmetric carbon atoms at the C12 and C22 positions in a single stereoselective step. Third, we installed the third quaternary asymmetric carbon center at the C9 position by an intramolecular acylation of a keto alcohol followed by successive O-methylation and C-methylation reactions with complete stereoselectivity. Through the exploitation of a deuterium kinetic isoptope effect, we then efficiently synthesized the alkyne segment. Next, a coupling reaction between the alkyne segment and the amino alcohol segment and several subsequent synthetic transformations afforded the bis-aminoacetalization precursor. Finally, bis-aminoacetalization reactions carried out in one-pot constructed the DEFG-ring system and culminated in the total synthesis of norzoanthamine. Our synthetic route to norzoanthamine also allowed access to other zoanthamine alkaloids from a common synthetic intermediate, by way of stereoselective introduction of the C19 methyl group for zoanthamine, and isoaromatization for construction of the aromatic A-ring in zoanthenol. The chemistry described here not only allowed us to overcome formidable synthetic challenges but also opened a completely chemical avenue to naturally occurring zoanthamine alkaloids and their synthetic derivatives.     

Applicability of molten carbonate fuel cells to various fuels

MCFCs can utilize CO rich and H₂ lean fuel, such as gasified biomass or gasified waste as a Pt catalyst is not used and Pt poisoning by CO does not occur. This feature has become very important due to the worldwide CO₂ depression requirements. CRIEPI has developed MCFC technologies in line with a governmental program, which mainly focused on natural gas fuel. However, CRIEPI has recently been focussing on technologies for various fuel applications. Single cells and stacks were tested with various gas compositions and showed stable performance even with high CO and high fuel utilization conditions. Gasified biomass or waste can contain many kinds of impurities such as H₂S, HCl, HF, NH₃, etc. The effects of these impurities were taken into account for single cells, and the permissible limits were estimated.     

Numerical analysis of the single electrode heat effect in molten carbonate fuel cells: temperature analysis of the electrolyte plate by applying irreversible thermodynamics

A temperature analysis model of a molten carbonate fuel cells (MCFC) stack is used to calculate the single electrode heat effects. The magnitude of heat which evolves from the cathode and absorbed at the anode is large, and in similar value to the electrical output of a MCFC. This suggests that the heat evolution of a single electrode causes a temperature difference between the electrodes. The temperature distribution in the electrolyte plate is evaluated to establish more accurate results concerning the temperature analysis model of the stack. The temperature distribution in the electrolyte plate is studied by applying irreversible thermodynamics. When the operating current density is less than 3000 A m^?2 and the thermal conductivity of the electrolyte is more than 2 W m^?1 K^?1, the temperature difference between cathode and anode is estimated to be less than approximately 1 K. This result proves that the temperature difference between the electrodes can be supposed constant in constructing the temperature analysis model of the MCFC stack. This results also allows us to construct a two‐dimensional heat production distribution in the cell plane and discrete heat production distribution in the stacking direction for the practical use of the temperature analysis model. Copyright © 2004 John Wiley & Sons, Ltd.     

Trend in Chlamydia trachomatis infection among pregnant women in the past ten years in Japan: significance of Chlamydia trachomatis seroprevalence

BACKGROUND AND OBJECTIVES: Chlamydia trachomatis infection is believed to be the most common bacterial sexually transmitted disease (STD) in industrialized countries. The objective of the current study was to assess the recent trend in the prevalence of C. trachomatis in Japan. GOAL OF THIS STUDY: To determine the trend in the seroprevalence for C. trachomatis among pregnant women in Nagasaki, Japan, during the past 10 years. STUDY DESIGN: The seroprevalence for C. trachomatis of 9,652 pregnant women of various ages screened in 1996 and 1997 was compared with those of 275 and 297 stocked samples from 1987 and 1992, respectively. Serum antibodies to C. trachomatis were detected by the enzyme immunoassay. Prospective samples of 33 seropositive cases were also analyzed to determine kinetics of the serum antibody titer. RESULTS: The seroprevalence has decreased in all age groups during the last 10 years. More than 70% of seropositive cases converted to be seronegative within 10 years. CONCLUSION: The prevalence of C. trachomatis has been decreasing among Japanese pregnant women.