Synthesis of Na-A and/or Na-X zeolite/porous carbon composites from carbonized rice husk

Na-A and/or Na-X zeolite/porous carbon composites were prepared under hydrothermal conditions by NaOH dissolution of silica first from carbonized rice husk followed by addition of NaAlO₂ and in situ crystallization of zeolites i.e., using a two-step process. When a one-step process was used, both Na-A and Na-X zeolites crystallized on the surface of carbon. Na-A or Na-X zeolite crystals were prepared on the porous carbonized rice husk at 90 °C for 2-6 h by changing the SiO₂/Al₂O₃, H₂O/Na₂O and Na₂O/SiO₂ molar ratios of precursors in the two-step process. The surface area and NH₄⁺-cation exchange capacity (CEC) of Na-A zeolite/porous carbon were found to be 171 m²/g and 506 meq/100 g, respectively, while those of Na-X zeolite/porous carbon composites were 676 m²/g and 317 meq/100 g, respectively. Na-A and Na-X zeolites are well-known microporous and hydrophilic materials while carbonized rice husk was found to be mesoporous (pores of ∼3.9 nm) and hydrophobic. These hybrid microporous-mesoporous and hydrophilic-hydrophobic composites are expected to be useful for decontamination of metal cations as well as organic contaminants simultaneously.     

A Tin Oxide Transparent Electrode Provides the Means for Rapid Time‐resolved pH Measurements: Application to Photoinduced Proton Transfer of Bacteriorhodopsin and Proteorhodopsin†

An electrochemical cell was previously reported in which bacteriorhodopsin (BR, purple membrane) was adsorbed on the surface of a transparent SnO₂ electrode, and illumination resulted in potential or current changes (Koyama et al., Science 265:762–765, 1994; Robertson and Lukashev, Biophys. J. 68:1507–1517, 1995; Koyama et al., Photochem. Photobiol. 68:400–406, 1998). In this paper, we concluded that pH changes caused by proton transfer by the deposited BR or proteorhodopsin (PR) films lead to the flash‐induced potential change in the SnO₂ electrode. Thus, the signals originate from BR and PR acting as light‐driven proton pumps. This conclusion was drawn from the following observations. (1) The relation between the potential of a bare electrode and pH is linear for a wide pH range. (2) The flash‐induced potential changes decrease with an increase in the buffer concentration. (3) The action spectrum of PR agrees well with the absorption spectrum. (4) The present electrode can monitor the pH change in the time range from 10 ms to several hundred milliseconds, as deduced by comparing the SnO₂ signal with the signals of pH‐sensitive dyes. Using this electrode system, flash‐induced proton transfer by BR was measured for a wide pH range from 2 to 10. From these data, we reconfirmed various pK_a values reported previously, indicating that the present method can give the correct pK_a values. This is the first report to estimate these pK_a values directly from the proton transfer. We then applied this method to flash‐induced proton transfer of PR. We observed proton uptake followed by release for the pH range from 4 to 9.5, and in other pH ranges, proton release followed by uptake was observed.     

CH double-pulsed PLIF measurement in turbulent premixed flame

The flame displacement speeds in turbulent premixed flames have been measured directly by the CH double-pulsed planar laser-induced fluorescence (PLIF). The CH double-pulsed PLIF systems consist of two independent conventional CH PLIF measurement systems and laser beams from each laser system are led to same optical pass using the difference of polarization. The highly time-resolved measurements are conducted in relatively high Reynolds number turbulent premixed flames on a swirl-stabilized combustor. Since the time interval of the successive CH PLIF can be selected to any optimum value for the purpose intended, both of the large scale dynamics and local displacement of the flame front can be discussed. By selecting an appropriate time interval (100–200 μs), deformations of the flame front are captured clearly. Successive CH fluorescence images reveal the burning/generating process of the unburned mixtures or the handgrip structures in burnt gas, which have been predicted by three-dimensional direct numerical simulations of turbulent premixed flames. To evaluate the local flame displacement speed directly from the successive CH images, a flame front identification scheme and a displacement vector evaluation scheme are developed. Direct measurements of flame displacement speed are conducted by selecting a minute time interval (≈30 μs) for different Reynolds number (Re _λ = 63.1–115.0). Local flame displacement speeds coincide well for different Reynolds number cases. Furthermore, comparisons of the mean flame displacement speed and the mean fluid velocity show that the convection in the turbulent flames will affect the flame displacement speed for high Reynolds number flames.     

Theoretical study of electronic structure for “inclined” CO chemisorbed on Pd (210) surface

Electronic structure for CO chemisorbed on Pd (210) surface has been calculated by the model potential Xα method which involves Bonifacic-Huzinaga's model potential and Slater's Xα potential. The results of the present calculations are consistent with the “inclined” CO model which was proposed by Madey et al. The results also show that the electronic structure of CO chemisorbed on Pd (210) surface resembles surprisingly those of CO on the other low-index planes where the CO molecular axis is supposed to be perpendicular to the surfaces.     

Partial synthesis of aromatic carotenoids,tedanin, agelaxanthin a,tethyatene, and renieratene

Aromatic carotenoids, tedanin, agelaxanthin A, and tethyatene were synthesized from 0- acetyl-6-citraurin derived from natural zeaxanthin, and tethyatene was further transformed into renieratene as the first example of aromatization of an alicyclic ring in carotenoids.     

Base-discriminating fluorescent (BDF) nucleoside: distinction of thymine by fluorescence quenching

A novel fluorescence BDF probe containing pyrene-labeled 7-deaza-2[prime or minute]-deoxyadenosine has been developed for the detection of thymine base on a target DNA.     

Synthesis and characterization of flavylium salts having three types color depending on recrystallization conditions

Three types of flavylium salts (FVs, yellow, green and red) have been synthesized and the colors depended on recrystallization conditions. The existence of these color states was confirmed by diffuse reflectance spectra. The spectra were almost the same as the absorption spectra in ethanol solution. The molecular state of FVs in crystals will be the same as that in solutions. The crystal colors of the FVs are controlled by the recrystallization conditions.     

A Convenient and Efficient Synthesis of SLeX Analogs

Described is the preparation and use of tetrasaccharide 1, which enables a rapid and preparative scale synthesis of sialyl Lewis X (SLeX) analogs having 1-O- and 2-N-disubstituted glucosamine (GlcN) moieties. Such modifications should bring a dramatic change of the physical and pharmacological properties of the SLeX analogs. Therefore, tetrasaccharide 1 is a convenient intermediate for the synthesis of various SLeX analogs, since it has convertible 2-(trimethylsilyl)ethyl (SE) glycoside and the free amino group on GlcN moiety. The intermediate 1 was constructed from a glucosamine derivative by a highly efficient combined use of enzymatic galactosylation/sialylation and chemical fucosylation. Thus obtained 1 was converted into SLeX analogs by N-substitution followed by transformation of SE glycoside into other glycosides and deprotection. These synthesized analogs were found to inhibit cell adhesion of HL-60 cells to recombinant soluble human E-selectin.     

Biosynthetic pathway of iridoid glucosides in Gardenia jasminoides f. grandiflora cell suspension cultures after iridodial cation formation

Administration of ²H- or ¹³C-labeled monoterpenes to $\text{Gardenia}$$\text{jasminoides}$ f. $\text{grandiflora}$ cell suspension cultures demonstrated that iridoid glucosides of the suspension cultures are biosynthesized, after iridodial cation formation from 10-oxocitral (3), via 8-epiiridodial (13), 8-epiiridotrial (14), boschnaloside (8-epiiridotrial glucoside) (12) and dehydroiridotrial glucoside (8). In addition, the coexistence of a route via iridodial cation (4), dehydroiridodial (6), dehydroiridotrial (15) and dehydroiridotrial glucoside (8) is conceivable.     

Solvent effect on radical polymerization of butyl acrylate

The propagation and termination rate constants k_p and k_t for the radical polymerization of butyl acrylate initiated by biacetyl have been measured by using the rotating-sector method, in various solvents at 30°C. The value of k_p and initiation rate R_i varied with solvents, while the value of k_t did not change with solvents except for benzonitrile. The variation of k_p with aromatic solvents has a trend against Hammett σ_p of the solvent substituents similar to that for methyl methacrylate or phenyl methacrylate except for the value in benzonitrile, when it is larger than the variation for methyl methacrylate or phenyl methacrylate. The larger variation of k_p for butyl acrylate is compatible with the view that the origin of the solvent effect lies in complex formation between the propagating radical and aromatic solvent molecules. The exceptional decrease in k_p and k_t in benzonitrile is explained by a contraction of the poly(butyl acrylate) chain in the poor solvent.