Hydrothermal Synthesis,Luminescence, and Phase Stability of Solid Solution Nanocrystals Based on Y3NbO7 and ZrO2

Cubic solid solution nanocrystals in the zirconia (ZrO₂)–yttrium niobate (Y₃NbO₇) system were directly formed at 180°C–240°C from the precursor solution mixtures of NbCl₅, ZrOCl₂, and YCl₃ under mild hydrothermal conditions in the presence of aqueous ammonia. The lattice parameter corresponding to cubic phase linearly changed according to the Vegard's law in the wide composition range of ZrO₂ (mol%) = 10–90 in the ZrO₂–1/4Y₃NbO₇ system. The progress of the formation of nanocrystalline solid solutions based on the Y₃NbO₇ was assisted via the presence of ZrO₂ component as a promoter with the same fluorite‐type structure. The optical band gap of the solid solutions was in the range 3.4–3.7 eV. Broadband emissions centered at 360–380 and 390 nm were observed for the nanocrystalline cubic solid solutions and pure cubic Y₃NbO₇, respectively, under excitation at 240 nm Xe lamp. The nanosized cubic crystallites of the solid solutions were maintained after heat treatment up to 800°C for 1 h air. The cubic phase of the solid solutions in the ZrO₂–1/4Y₃NbO₇ system was maintained after heat treatment at 1400°C in air.     

Dynamic friction property and mechanism of line‐type thermoplastic polymer materials for new optical wiring technology

We have been developing a new optical wiring technology for installing indoor optical fiber cables directly into apartment houses for fiber to the home. The technology must minimize the friction of optical fiber cable. We reviewed many studies on friction behavior, and studied the friction properties of a wide variety of polymer sheets and optical fiber cables, and considered the friction mechanism. Relatively, soft polymer materials exhibited stick‐slip behavior and the hard polymers exhibited constant slip behavior. Lubricants are effective in reducing friction and play a dominant role as regards the friction property. Silicon and fluorocarbon agents play some role in converting the stick‐slip characteristic into constant slip behavior. A certain roughness is effective in reducing friction. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers.     

Synthetic Efforts for Stereo Structure Determination of Cytotoxic Marine Natural Product Pericosines as Metabolites of Periconia sp. from Sea Hare

Pericosines are unique C₇ cyclohexenoid metabolites of Periconia byssoides OUPS-N133 fungus that was originally isolated from the sea hare, Aplysia kurodai. Pericosines show significant in vitro cytotoxicity against P388 lymphocytic leukemia cells. Pericosine A, in particular, shows the most potent activity and significant in vivo antitumor activity against P388 cells. Thus, pericosines are promising candidates for seed compounds of anticancer drugs. However, before the total syntheses of pericosines were accomplished, their stereo structures could not be determined by spectral analyses because they have multi-functionalized cyclohexenoid structures with torsional strain. In this review, synthetic efforts for pericosines in this decade are surveyed.     

Direct Formation and Luminescence Properties of Yttrium Niobate YNbO4 Nanocrystals via Hydrothermal Method

Yttrium niobate YNbO₄ nanocrystals with ellipsoidal morphology were directly formed from the precursor solution mixtures of YCl₃ and NbCl₅ under weakly basic conditions in the presence of aqueous ammonia by hydrothermal method. The hydrothermal treatment at 180°C for 5 h was necessary to obtain nanocrystals (18 nm) with sufficient crystallinity. The optical band gap of the as‐prepared samples was 3.6 eV. The as‐prepared YNbO₄ nanocrystals showed UV‐blue and broadband emission centered at 405 nm under excitation at 235 nm, which was due to the blue recombination luminescence, associated with charge‐transfer transitions involving the tetrahedral NbO₄ group. The emission intensity increased with increased hydrothermal treatment temperature. The photoluminescence intensity of the YNbO₄ was extremely improved via heating above 1000°C in air, which was accompanied by the increase in the optical band gap from 3.6 to 4.0 eV. By heat treatment at 1300°C, the intensity of the UV‐blue and broadband emission (with maximum at 400 nm) for the YNbO₄ became more than 22.5 times as strong as that before heat treatment.     

Simultaneous temperature measurements of bearing and seal parts of a swash plate type axial piston pump — effects of piston clearance and fluid property

Temperatures of three bearing and seal parts of a swash plate type axial piston pump were measured simultaneously using a slip ring with thermocouples’ amplifiers. The rotating cylinder block had five thermocouples, the swash-plate had four, and the valve-plate had four. Three sets of pistons with different diameters were prepared. Hydraulic mineral oil with VG22 and a water-glycol type hydraulic oil with VG32 were used as test fluids. The maximum discharge pressure was 20 MPa; the maximum rotational speed was 25 rps. The inlet oil temperature was 20–40°C. Temperatures and temperature differences between the bottom-dead-center and the top-dead-center increased concomitantly with the discharge pressure. For larger piston clearance ratios, the temperatures rose monotonically. The bearing and seal parts were markedly hotter than the discharge oil. Temperatures rose much less using the water-glycol type oil than when using the mineral oil.     

海苔发酵提取物对原发性高血压大鼠的降压效果研究

使用可以产生GABA的植物性乳酸菌对海苔进行发酵,得到富含10.5%GABA的海苔发酵提取物。本实验验证了海苔发酵提取物对原发性高血压模型大鼠(SHR)的降压效果。单次经口灌胃给药实验中,分别以2mg/kg·bw和0.2mg/kg·bw剂量的海苔发酵提取物一次性灌胃给药,给药后2、5、9、24h进行血压测定。结果表明,海苔发酵提取物2mg/kg·bw剂量组在给药后5h和24h均有显著降压效果(p<0.05,p<0.01)。长期摄食给药实验中,含有海苔发酵提取物0.001%和0.003%的饲料剂量组对成长期SHR和老龄期SHR分别摄食给药,给药后每2～3d进行一次血压和体重测量,结果显示含有海苔发酵提取物0.003%的饲料剂量组使成长期SHR和老龄期SHR血压均显著下降(p<0.01,p<0.05)。     

The Development of the New Data Acquisition System Without Hardware Trigger for the Super-Kamiokande Experiment

An online system of the underground neutrino detector, Super-Kamiokande is scheduled to be upgraded in 2008 together with front-end electronics. This detector consists of 50 000 tons of pure water equipped with about 13 000 photo-multipliers (PMTs) to detect Cherenkov light. The new online system is required to accept the dataflow of up to 800 MB/s from the front-end electronics and process them for the offline analysis. We will utilize a Gigabit Ethernet network and parallel data processing to handle this large amount of flow. In the new data acquisition scheme, we will not use a hardware event-trigger but read out every hit data from the front-end electronics and process them by the online farm. Therefore, there is no threshold of the number of PMT hits and the detector will become more sensitive to important cosmic-ray events such as relic neutrino from supernova and low energy solar neutrino. In addition to that, a dead-timeless system is desirable for the continuous measurement 365 days a year. In this paper, the detailed design of the upgraded online system and testing activities using prototypes will be described.     

Direct Introduction of OH Group to sp2-Carbon on Platinum-Loaded Titanium Oxide Photocatalyst

Photocatalytic oxidation of various organic compounds by using molecular oxygen has been broadly investigated as a valuable synthetic route, but the application has been still limited because the active oxygen species from the molecular oxygen are usually difficult to be controlled. In this short review, we describe two kinds of photocatalytic oxygenation with H₂O molecule as a source of OH group; i.e., photocatalytic hydroxylation of aromatic ring and photocatalytic hydration of alkene, on Pt/TiO₂ photocatalyst. In both reactions, a photoformed active oxygen species attacks to the sp²-carbon to form a reaction intermediate. In the aromatic ring hydroxylation, the elimination of the H atom from the intermediate proceeds while the conjugate double bond of the aromatic ring maintains. In the alkene hydration, the addition of the H radical to the intermediate results in forming an alcohols molecule with the saturation of the double bond. In the former case, the electrophilic property of the active oxygen species predominantly determines the orientation of the OH group in the produced phenols. On the other hand, in the latter case, the thermodynamic stability of the intermediate radical species leads the active oxygen species preferentially to the terminal sp²-carbon, which makes it possible to provide the unique regioselectivity of alcohol according to the anti-Markovnikov rule.     

Differential Regulation of Bilastine Affinity for Human Histamine H1 Receptors by Lys 179 and Lys 191 via Its Binding Enthalpy and Entropy

Bilastine, a zwitterionic second-generation antihistamine containing a carboxyl group, has higher selectivity for H₁ receptors than first-generation antihistamines. Ligand-receptor docking simulations have suggested that the electrostatic interaction between the carboxyl group of second-generation antihistamines and the amino group of Lys179^ECL2 and Lys191^5.39 of human H₁ receptors might contribute to increased affinity of these antihistamines to H₁ receptors. In this study, we evaluated the roles of Lys179^ECL2 and Lys191^5.39 in regulating the electrostatic and hydrophobic binding of bilastine to H₁ receptors by thermodynamic analyses. The binding enthalpy and entropy of bilastine were estimated from the van ’t Hoff equation using the dissociation constants. These constants were obtained from the displacement curves against the binding of [³H] mepyramine to membrane preparations of Chinese hamster ovary cells expressing wild-type human H₁ receptors and their Lys179^ECL2 or Lys191^5.39 mutants to alanine at various temperatures. We found that the binding of bilastine to wild-type H₁ receptors occurred by enthalpy-dependent binding forces and, more dominantly, entropy-dependent binding forces. The mutation of Lys179^ECL2 and Lys191^5.39 to alanine reduced the affinity of bilastine to H₁ receptors by reducing enthalpy- and entropy-dependent binding forces, respectively. These results suggest that Lys179^ECL2 and Lys191^5.39 differentially contribute to the increased binding affinity to bilastine via electrostatic and hydrophobic binding forces.