An experimental study of the characteristics of a Darrieus turbine for tidal power generation

The Darrieus turbine was initially developed for wind turbines. An example of its application to water turbines is found in the Darrieus turbine installed in a duct for low head power generation, but no example is known of its application in a natural water channel. The authors have developed a Darrieus turbine that is suitable for tidal current power generation with the aim of establishing tidal current power generation technology through demonstrations in test channels and oceans. The efficiency of tidal current power generation is influenced by the characteristics of the turbine. The characteristics of the Darrieus turbine are mainly affected by the solidity and the number of blades. The Darrieus turbine was tested in test channels to find the most suitable values for the rotor solidity and the number of blades. This paper describes and examines those test results. © 2000 Scripta Technica, Electr Eng Jpn, 132(3): 38–47, 2000     

Discovery of Pyridone‐Based Histone Deacetylase Inhibitors: Approaches for Metabolic Stability

Histone deacetylases (HDACs) are important enzymes in epigenetic regulation and are therapeutic targets for cancer. Most zinc‐dependent HDACs induce proliferation, dedifferentiation, and anti‐apoptotic effects in cancer cells. We designed and synthesized a new series of pyridone‐based HDAC inhibitors that have a pyridone ring in the core structure and a conjugated system with an olefin connecting the hydroxamic acid moiety. Consequently, most of the selected pyridone‐based HDAC inhibitors showed similar or higher inhibition profiles in addition to remarkable metabolic stability against hydrolysis relative to the corresponding lactam‐based HDAC inhibitors. Furthermore, the selectivity of the novel pyridine‐based compounds was evaluated across all of the HDAC isoforms. One of these compounds, (E)‐N‐hydroxy‐3‐{1‐[3‐(naphthalen‐2‐yl)propyl]‐2‐oxo‐1,2‐dihydropyridin‐3‐yl}acrylamide, exhibited the highest level of HDAC inhibition (IC₅₀=0.07 μM ), highly selective inhibition of class I HDAC1 and class II HDAC6 enzymes, metabolic stability in mouse liver microsomal studies, and effective growth inhibition of various cancer cell lines. Docking studies indicated that a long alkyl linker and bulky hydrophobic cap groups affect in vitro activities. Overall, the findings reported herein regarding pyridone‐based HDAC inhibitors can be used to guide future research efforts to develop new and effective anticancer therapeutics.     

Robust numerical simulation of pressure swing adsorption process with strong adsorbate CO2

Governing equations describing the pressure swing adsorption processes with strong adsorbates were converted into dimensionless forms. The characteristic scales reflecting the system dimensions, operating conditions and physical properties including the isotherms indicated that the gas-phase convection mass transfer balances the adsorbent-phase mass accumulation. The gas-phase accumulation should not be considered a dominant mass transfer mode and would change rapidly with time. In order to avoid stiffness of time derivatives of the gas-phase accumulation and to obtain robust numerical solutions through the diagonally dominant matrices, the two leading terms should coexist in the difference equation. Through the present numerical strategy the convergence of the numerical integration and the accuracy of the simulated results were guaranteed for a wide range of time discretization. The algorithm was found to successfully predict the reasonable behaviors of process variables even for non-isothermal operations.     

Chemically induced reduction: A viable process for synthesizing γ-TiAl based intermetallic matrix composite powders containing nanocrystalline TiC

A chemically induced reduction process has been developed for synthesizing intermetallic matrix composites (IMCs) consisting of titanium aluminide and titanium carbide. The process involves the reduction of metal chlorides (TiCl₄ and AlCl₃) with metallic lithium in polar organic solvents such as acetonitrile (MeCN) and tetrahydrofuran (THF) to form a colloidal precursor. The as-prepared precursors have been either directly heat treated in ultra-high-purity argon (UHP-Ar) or pretreated in hydrogen (H₂) followed by further heat treatment in UHP-Ar. The powders have been characterized primarily using X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Results of the structural analyses conducted on the heat-treated precursors derived using MeCN as a solvent indicate the formation of either single-phase titanium carbide (TiC) or a composite mixture of γ-TiAl and nanocrystalline TiC, depending on the heat-treatment conditions. The formation of TiC is related to the strong interaction between TiCl₄ and the polar organic solvents, resulting in the formation of adducts which contain primary Ti-C linkages. Pretreatment of the precursors derived using MeCN as a solvent in H₂ promotes the removal of carbon and results in the formation of the composite mixture of γ-TiAl and TiC after subsequent Ar treatment at 1200 °C. At this stage, washing the pretreated powders in water helps to minimize and even eliminate any impurity phases to a large extent, leaving behind phase-pure composites containing γ-TiAl and TiC after the final Ar treatment. However, extended pretreatment in H₂ appears to be ineffective toward removal of additional carbon and leads to formation of hydride-phase impurities. On the other hand, the reductive reaction conducted using THF as a solvent results in minimizing the amount of carbon while inducing the formation of γ-TiAl during direct Ar treatment of the precursors. This is because of the weaker interaction between TiCl₄ and THF. Transmission electron microscopy was used to characterize the size distribution of the constituent phases. The analysis shows that the composite synthesized using these chemical approaches consist of discrete nanocrystalline TiC particles (<20 nm) that are uniformly distributed intermixed with submicron sized γ-TiAl (0.1 to 0.2 μm). Thus, the new chemical process proposed in this study demonstrates the potential for synthesizing in situ composites containing fine distribution of γ-TiAl and nanocrystalline TiC. Such composites could potentially exhibit unique mechanical properties and deformation behavior useful for high-temperature structural applications.     

The Nodal SDW Gap and the Superconducting Gap in?BaFe2?x Co x As2

The spin density wave (SDW) transition in BaFe₂As₂ and the superconducting transition in BaFe_1.84Co_0.16As₂ were investigated by Raman scattering. The symmetries of the nodal SDW gap at 400?cm^?1 and the superconducting gap at 75?cm^?1 are both?B _2g. The superconducting coherent peak energy is smaller than the gap energy of the hole pocket, indicating that the peak is the resonant peak in the S _?? superconductor. The superconducting symmetry is given by B _2g in the orbital combination and A _1g (S _??) in the momentum space. The exchange interaction energies are estimated from the two-magnon peak.     

Gamma-aminobutyric acid fermentation in MRS-based medium by the fructophilic Lactiplantibacillus plantarum Y7

Food Science and Biotechnology - Among the key metabolites produced by probiotic lactic acid bacteria (LAB), the use of gamma-aminobutyric acid (GABA), which alleviates hypertension, depression,...     

Preparation of novel (1-->3)-beta-D-glucans having reducing glucose side chains

Novel (1-->3)-beta-D-glucans (GPBCD, GPECD, GP6CD, and GP3CD) having reducing glucose side chains were prepared from a linear (1-->3)-beta-D-glucan (curdlan: CD) with halogeno glucose isopropylidene derivatives in dimethyl sulfoxide containing dimsyl sodium, followed by treatment with 40% trifluoroacetic acid to remove protecting isopropylidene groups. The side chain glucose moiety was linked or directly or through a spacer at various positions except for its anomeric carbon.     

New Phases for the Orientational Ordering of Quantum Rotors: H2 on Hexagonal BN

The phase diagram for the orientational ordering of 2D films of ortho–para H ₂ mixtures has been explored for both commensurate and incommensurate monolayer coverages on hexagonal BN. NMR techniques were used to study ortho concentrations 0.30<x<0.74and temperatures 0.05 <T<4.2. Three distinctly different classes of line shapes were observed and we interpret these in terms of the different phases predicted for the orientational ordering in 2D. At high concentrations a Pake doublet line shape was observed which is characteristic of the pinwheel (PW) ordering predicted by Harris and Berlinsky. For intermediate concentrations a distinctive helmet shaped NMR line is observed which is the signature of a quadrupolar glass state. This line shape was seen only for commensurate coverages. At low concentrations (x<0.45) a new very sharply defined Pake doublet shape is seen which corresponds to a very narrow distribution of order parameters. We interpret this latter phase as a herringbone (HB) ordering.     

Gas chromatographic analysis of reduction products of paraquat, diquat and the related compounds: reductive cleavage in the pyridine ring on N-alkylpyridinium derivatives with NaBH4-NiCl2 reduction system, and inhibition of the cleavage

When N-alkylpyridinium derivatives were reduced with sodium borohydride-nickel (II) chloride reduction system, reductive cleavage occurred at the C-N bond in the pyridine ring of N-alkylpyridinium derivatives to give a small amount of reductive cleavage product along with the major perhydrogenated product. It was presumed in the previous report that this reductive cleavage in the pyridine ring proceeded through a complex of nickel ion and 1,2,3,6-tetrahydropyridine derivatives produced with NaBH4 alone reduction. The abundances of these reductive cleavage products arising from N-alkylpyridinium derivatives, i.e., paraquat, diquat and so on, are capable of giving a bad effect on the accuracy of gas chromatographic analysis. For the purpose of inhibition of the reductive cleavage in this reduction system, a suitable catalyst was examined. In addition, we pursued whether borane-1,2,3,6-tetrahydropyridine derivative complexes arose from N-alkylpyridinium derivatives by NaBH4 alone reduction or not, and whether these borane-amine complexes were the precursors of reductive cleavage products or not. N-Alkyl-1,2,3,6-tetrahydropyridine derivatives (III-I, IV-I, VI-I, VII-I and VIII-I) and the corresponding borane-amine complexes (III-II, IV-II, VI-II, VII-II and VIII-II) were synthesized by NaBH4 reduction in aqueous solution of N-alkylpyridinium salts, i.e. I, II, 1,4-dimethylpyridinium iodide (III), 1-dodecylpyridinium chloride (IV), 1,1'-diethyl-4,4'-dipyridinium dichloride (V), 1-methyl-4-phenylpyridinium iodide (VI), 1-n-propylpyridinium iodide (VII) and 1-n-butylpyridinium iodide (VIII). The structure of the borane-amine complexes were proved by the Mass spectrometry and 1H- and 13C-NMR analysis. The NiCl2-NaBH4 reduction of the borane-amine complexes gave the perhydrogenated products alone, but not reductive cleavage products. In conclusion, it was recognized that the precursors of reductive cleavage products were not borane-amine complexes, but 1,2,3,6-tetrahydropyridine. Furthermore, it was found the reductive cleavage at the C-N bond in the pyridine ring of these 1,2,3,6-tetrahydropyridine derivatives was hindered by applying Amberlite-Ni2B, NaBH4 reduction system.