Control of oscillating combustion and noise based on local flame structure

To control combustion oscillations, the characteristics of an oscillating swirl injection premixed flame have been investigated, and control of oscillating combustion and noise based on local flame structure has been conducted. The r.m.s. value of pressure fluctuations and noise level show significantly large values between = 0.8 and 1.1. The beating of pressure fluctuations is observed for the large oscillating flame conditions in this combustor. Relationship between beating of pressure fluctuations and local flame structure was observed by the simultaneous measurement of CH/OH planar laser induced fluorescence and pressure fluctuations. The local flame structure and beating of pressure fluctuations are related and the most complicated flame is formed in the middle pressure fluctuating region of beating. The beating of pressure fluctuations, which plays important roles in noise generation and nitric oxide emission in this combustor, could be controlled by injecting secondary fuel into the recirculating region of oscillating flames. Injecting secondary fuel prevented lean blowout, and low NO_x combustion was also achieved even for the case of pure methane injection as a secondary fuel. By injecting secondary fuel into the recirculating region near the swirl injector, the flame lifted from the swirl injector and its reaction region became uniform and widespread, hence resulting in low nitric oxide emission. Secondary mixture injection, fuel diluted with air, is not effective for control of combustion oscillations suppression and lean blowout prevention.     

Synthesis and Properties of Hydrophilic Copolymers Containing 5-Fluorouracil,Thymine, or Adenine

Hydrophilic copolymers containing 5-fluorouracil (5-FU), thymine, or adenine were prepared by the free-radical copolymerization of methacryloyl-type monomers containing them with water-soluble vinyl monomers such as acrylic acid, methacrylic acid, vinylpyrroli-done, acrylamide, and 4(5)-vinylimidazole with AIBN as initiator. Complex formation between the copolymers and RNA and between the copolymers having complementary nucleic acid bases in aqueous solution and a DMSO-ethylene glycol was studied by means of UV spectroscopy. These copolymers were found to release the N-hydroxyethyl derivatives of 5-FU, thymine, or adenine by hydrolysis of the ester of the polymer side chain under mild conditions. The effects of the kind of water-soluble comonomer, temperature, pH, and the imidazole group as catalyst on the hydrolysis of the ester are discussed.     

Design and synthesis of a novel imidazolium-based ionic liquid with planar chirality

As the first example of a planar chiral ionic liquid, a cyclophane-type imidazolium salt was synthesized; its potential use in chiral recognition was demonstrated by 1H NMR studies.     

Dramatically improved catalytic activity of an artificial (S)-selective arylmalonate decarboxylase by structure-guided directed evolution

Using three rounds of structure-guided directed evolution, the catalytic activity of the (S)-selective arylmalonate decarboxylase variant G74C/C188S could be increased up to 920-fold. The best variant had a 220-fold improved activity in the production of (S)-naproxen with excellent enantioselectivity (>99% ee).     

Ce-doped ZnO (Ce(x)Zn(1-x)O) becomes an efficient visible-light-sensitive photocatalyst by co-catalyst (Cu2+) grafting

We have fabricated an efficient visible-light-sensitive Cu(2+)-grafted Ce-doped ZnO photocatalyst (Cu(2+)-Ce(x)Zn(1-x)O) by adopting a metal ion doping and co-catalyst modification. Impurity states were formed below the conduction band (CB) edge in Ce(x)Zn(1-x)O, and these impurity states induce the visible-light absorption. Ce(x)Zn(1-x)O without a Cu(2+)-co-catalyst showed negligible visible-light activity due to the low reduction power of electrons in impurity levels. Surprisingly, Cu(2+)-modification over Ce(x)Zn(1-x)O drastically increased its visible-light activity. Excited electrons in impurity states can transfer to the Cu(2+)-ions on the surface and form Cu(2+)/Cu(+) redox couples, which cause the efficient oxygen reduction through a multi-electron reduction process. One of the striking features of the present study is that the metal doped semiconductors which were inactive due to their impurity states become efficient visible-light photocatalysts upon co-catalyst modification. The successful strategy used here for designing a highly active visible-light photocatalyst would provide numerous opportunities to develop an efficient metal-ion based visible-light photocatalyst.     

Single-crystalline rutile TiO2 hollow spheres: room-temperature synthesis, tailored visible-light-extinction, and effective scattering layer for quantum dot-sensitized solar cells

A general synthesis of inorganic single-crystalline hollow spheres has been achieved through a mechanism analogous to the Kirkendall effect, based on a simple one-step laser process performed at room temperature. Taking TiO(2) as an example, we describe the laser process by investigating the influence of experimental parameters, for example, laser wavelength, laser fluence/irradiation time, liquid medium, and concentration of starting materials, on the formation of hollow spheres. It was found that the size-tailored TiO(2) hollow spheres demonstrate tunable light scattering over a wide visible-light range. Inspired by the effect of light scattering, we introduced the TiO(2) hollow sphere's scattering layer in quantum dot-sensitized solar cells and achieved a current notable 10% improvement of solar-to-electric conversion efficiency, indicating that TiO(2) hollow spheres are potential candidates in optical and optoelectronic devices.     

A naphthodithiophene-diketopyrrolopyrrole donor molecule for efficient solution-processed solar cells

We report the synthesis, characterization, and first implementation of a naphtho[2,3-b:6,7-b']dithiophene (NDT)-based donor molecule in highly efficient organic photovoltaics (OPVs). When NDT(TDPP)(2) (TDPP = thiophene-capped diketopyrrolopyrrole) is combined with the electron acceptor PC(61)BM, a power conversion efficiency (PCE) of 4.06 ± 0.06% is achieved-a record for a PC(61)BM-based small-molecule OPV. The substantial PCE is attributed to the broad, high oscillator strength visible absorption, the ordered molecular packing, and an exceptional hole mobility of NDT(TDPP)(2).     

The conjugative metabolism of 4-methylumbelliferone and deconjugation to the parent drug examined by isolated perfused liver and in vitro liver homogenate of rats

We examined the disposition of 4-methylumbelliferone (4-MU) and its conjugative metabolites, glucuronide (4-MUG) and sulfate (4-MUS), using a single-pass rat liver perfusion system. When 4-MU was delivered, the steady-state hepatic extraction ratio for 4-MU was very high (approximately 1.0) and its conjugative metabolites, 4-MUG and 4-MUS, appeared to a large extent in the effluent perfusate. The biliary excretion rate of the 4-MUG conjugated from 4-MU was 44% of the infusion rate at the steady-state, whereas those of 4-MU and 4-MUS were less than 1% of the infusion rate. When 4-MUG was delivered, the steady-state hepatic extraction ratio for 4-MUG was very low (less than 0.05) and the removal rate of 4-MUG from the perfusate was almost identical to the excretion rate of 4-MUG into the bile, while 4-MU and 4-MUS were slightly excreted into the bile (1% of the total biliary excretion rate), suggesting that a little deconjugation of 4-MUG to 4-MU occurred in the liver. Similarly, 4-MU and 4-MUS were not detectable in the effluent perfusate. The apparent extraction ratio (Eapp) for the intracellularly conjugated 4-MUG was approximately twenty times higher than that for the pre-conjugated 4-MUG. This discrepancy between the values of Eapp for the intracellularly conjugated and pre-conjugated 4-MUG might be attributed mainly to the diffusional barrier for the metabolite between the blood and hepatocytes, as suggested in the previous simulation (J. Pharmacokin, Biopharm., 15, 399 (1987].(ABSTRACT TRUNCATED AT 250 WORDS)