Decomposition of chlorofluorocarbons on TiO2ZrO2

The decomposition of chlorofluorocarbons (CFCs) in the presence of water was examined over a variety of solid acid catalysts. The TiO₂ZrO₂ catalyst was found to have the highest activity and longest life among the catalysts examined. The activity of the TiO₂ZrO₂ catalysts depended upon the content of TiO₂. At the contents of TiO₂ from 58 to 90 mole%, the TiO₂ZrO₂ catalysts exhibited high activity, and these catalysts were proven to contain TiZrO₄ crystal. From the study of the XRD peak intensity of the TiZrO₄ crystal, it was highest on the TZ-58 which contained 58 mole% of TiO₂, and decreased with increasing the content of TiO₂. Furthermore, the conversion of CFC113 measured at 673 K was highest at TZ-58, and decreased gradually with increasing TiO₂ content. Therefore, the TiZrO₄ crystal influences the activity of decomposition of CFC113. However, the TiO₂ZrO₂ catalyst was gradually deactivated during the reaction due to the elimination of titanium atoms. A good relationship was found between the activity on TiO₂ZrO₂ catalyst and bond energy of CCl in the compounds of chlorofluorocarbons and hydrochlorocarbons, suggesting that the rate controlling step was the cleavage of CCl bond.     

Preparation and structure of poly(vinyl alcohol)–poly(vinyl acetate) composite porous membrane

The preparation of poly(vinyl alcohol) (PVA)–poly(vinyl acetate) (PVAc) composite porous membrane was investigated by extracting PVAc with solvent from films of PVAc lattices which were obtained by the emulsion polymerization of vinyl acetate (VAc) in the presence of PVA. The formation of the porous membrane depended upon whether or not PVAc in the latex film was easily extracted with solvent. In the case of using hydrogen peroxide (HPO)–tartaric acid (TA) as an initiator, in the film of the latex which was produced from the batch method in which all ingredients of the batch were put into the reaction vessel before starting polymerization, PVAc could be extracted over 90% of total PVAc with common organic solvents. In the film of the latex which was produced from the dropwise addition method of VAc and initiator, the PVAc extraction was about 20-30%. On the other hand, in the case of using ammonium persulfate as an initiator, the desired porous membrane was not obtained. The structure of the porous membrane obtained from the latex of the batch method by using HPO—TA consisted of spherical cells which were made up of PVA and grafted PVAc or insoluble PVAc like microgels, which were not extracted with organic solvent and were connected by small pores. The PVA—PVAc composite porous membrane is permeated by n-hexane with 5.58 × 10² mL/cm²·s at 0.5 kg/cm², by benzene with only 1.33 × 10^?3mL/cm²·s even at 60 kg/cm².     

Effective Coke Removal in Methane to Benzene (MTB) Reaction on Mo/HZSM-5 Catalyst by H2 and H2O Co-addition to Methane

The catalytic dehydro-aromatization reaction over Mo/HZSM-5 catalyst was drastically stabilized by the co-addition of 5.4% H₂ and 1.8% H₂O to methane feed at 750 °C, 0.3 MPa and methane space velocity of 3000 mL g⁻¹ h⁻¹, suppressing the coke formation effectively, compared with single hydrogen or steam addition.     

Effect of polymer density on polyethylene hollow fiber membrane formation via thermally induced phase separation

Microporous high‐density polyethylene (HDPE) and low‐density polyethylene (LDPE) hollow fiber membranes were prepared from polyethylene–diisodecyl phthalate solution via thermally induced phase separation. Effect of the polyethylene density on the membrane structure and performance was investigated. The HDPE membrane showed about five times higher water permeability than the LDPE membrane because it had the larger pore and the higher porosity at the outer membrane surface. The formation of the larger pore was owing to both the initial larger structure formed by spinodal decomposition and the suppression of the diluent evaporation from the outer membrane surface due to the higher solution viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 471–474, 2004     

Antitumor activity of synthetic alkylphospholipids with or without PAF activity

1-O-Octadecyl-2-O-methyl-sn-glycero-3-phosphocholine (ET-18-OMe) has been reported to possess definite antitumor activity in vivo. Twenty-two alkyl lysophospholipid analogs were chemically synthesized, and their antitumor activity against mouse experimental tumors (Sarcoma 180, MM46, P388) was examined. Among them, 1-O-octadecyl-2-O-acetoacetyl-rac-glycerol-3-phosphocholine was found to show antitumor activity similar to ET-18-OMe with less acute toxicity. Intravenous injection of the ET-18-OMe withsn-3 configuration retarded the subcutaneous growth of Sarcoma 180 cells effectively, while the growth inhibition by thesn-1 isomer was much less effective. This stereospecificity was similar to that observed in their activities as platelet-activating factor (PAF) agonists. The acetoacetyl compound, another PAF agonist, showed similar stereospecific antitumor action in vivo. These findings suggest that some alkyl lysophospholipids may activate host cells to a cytostatic stage against tumor cells in vivo through binding to a PAF receptor. Our preliminary results indicated that the responsible cells under these conditions might be primarily immature macrophages present in the bone marrow. No appreciable or even adverse stereospecificity was observed in the different sets of experiments where the activity of ET-18-OMe against MM46 tumor cells in vivo or the direct cytotoxicity against human promyelocytic leukemia HL-60 cells in vitro was examined. Under, some conditions, the antitumor activity of ET-18-OMe in vivo may be revealed through direct cytotoxicity and/or modulation of the host defense system by “nonspecific” mechanisms. Some alkylphospholipids without PAF activity may also show antitumor activity through similar, “nonspecific” mechanisms.     

Design of new catalysts for ecological high-quality transportation fuels by combinatorial computational chemistry and tight-binding quantum chemical molecular dynamics approaches

Recently, we introduced a concept of combinatorial chemistry to computational chemistry and proposed a new method called “combinatorial computational chemistry”, which enables us to perform a theoretical high-throughput screening of catalysts. In the present paper, we reviewed our recent application of our combinatorial computational chemistry approach to the design of new catalysts for high-quality transportation fuels. By using our combinatorial computational chemistry techniques, we succeeded to predict new catalysts for methanol synthesis and Fischer–Tropsch synthesis. Moreover, we have succeeded in the development of chemical reaction dynamics simulator based on our original tight-binding quantum chemical molecular dynamics method. This program realizes more than 5000 times acceleration compared to the regular first-principles molecular dynamics method. Electronic- and atomic-level information on the catalytic reaction dynamics at reaction temperatures significantly contributes the catalyst design and development. Hence, we also summarized our recent applications of the above quantum chemical molecular dynamics method to the clarification of the methanol synthesis dynamics in this review.     

Allelopathic Effects of Volatile Monoterpenoids Produced by <Emphasis Type="Italic">Salvia leucophylla</Emphasis>: Inhibition of Cell Proliferation and DNA Synthesis in the Root Apical Meristem of <Emphasis Type="Italic">Brassica campestris</Emphasis> Seedlings

Salvia leucophylla, a shrub observed in coastal south California, produces several volatile monoterpenoids (camphor, 1,8-cineole, -pinene, -pinene, and camphene) that potentially act as allelochemicals. The effects of these were examined using Brassica campestris as the test plant. Camphor, 1,8-cineole, and -pinene inhibited germination of B. campestris seeds at high concentrations, whereas -pinene and camphene did not. Root growth was inhibited by all five monoterpenoids in a dose-dependent manner, but hypocotyl growth was largely unaffected. The monoterpenoids did not alter the sizes of matured cells in either hypocotyls or roots, indicating that cell expansion is relatively insensitive to these compounds. They did not decrease the mitotic index in the shoot apical region, but specifically lowered mitotic index in the root apical meristem. Moreover, morphological and biochemical analyses on the incorporation of 5-bromo-2-deoxyuridine into DNA demonstrated that the monoterpenoids inhibit both cell-nuclear and organelle DNA synthesis in the root apical meristem. These results suggest that the monoterpenoids produced by S. leucophylla could interfere with the growth of other plants in its vicinity through inhibition of cell proliferation in the root apical meristem.     

Intrinsic Elastic, Dielectric, and Piezoelectric Losses in Lead Zirconate Titanate Ceramics Determined by an Immittance-Fitting Method

The material coefficients of "soft" and "hard" lead zirconate titanate (PZT) ceramics were determined as complex values by the nonlinear least-squares-fitting of immittance data measured for length-extensional bar resonators. The piezoelectric d -constant should be a complex value to obtain a best fitting between observed and calculated results. Because the elastic, dielectric, and piezoelectric losses determined in this process were not "intrinsic" losses, a calculation process to evaluate the "intrinsic" losses was proposed. It was confirmed that the intrinsic losses were smaller than the corresponding extrinsic losses. The intrinsic piezoelectric loss existed in both soft and hard PZTs; ∼50% of the loss of piezoelectric d -constant was derived from the elastic and dielectric losses. The most notable difference between the soft and hard PZTs was observed in their elastic losses.     

Synthesis and electrode performance of layered nickel dioxide containing alkaline ions

Several polymorphs of layered nickel dioxide were prepared by using the chemical insertion of alkaline ions into Li_0.10NiO₂. We used aqueous AOH (A = Li, Na, K) solutions as reducing agents. Sodium and potassium insertion resulted in hydrated layered compounds that can be classified as γ-NiOOH with high crystallinity, while lithium insertion occurred without hydration. We discuss the coordination environment around the A⁺ ions for these inserted compounds. The thermal behavior, analyzed using high temperature (HT) X-ray diffraction (XRD) and thermogravimetric (TG) measurements, indicated that heating the hydrate at 150 °C yielded its dehydrate. The electrode performance of the nickelate was studied in lithium cells. We discuss the effect of interlayer water on cell rechargeability and the similarity between these nickelate and hydrated manganese dioxide (birnessite).     

New multicolor and rewritable holographic polymer film for three‐dimensional holographic display

We have developed a new multicolor holographic polymer film. Our holographic polymer film contains 3‐[(2,4,6‐trichloro)azo]‐9H‐carbazole‐9‐ethanol (A‐1) and poly(methyl methacrylate). The holographic polymer film can be recorded with a holographic image without applying an external electric field. The diffraction efficiency was 57% at A‐1 with a 20 wt% of dope ratio. The writable holographic image writing for the holographic polymer film step used the silver halide photographic emulsion master plate 532‐nm laser beam under the nonelectric field. After the copy hologram is formed, our holographic polymer film can be displayed in red and green holographic images. Even though our holographic polymer film is rewritten over 200 times, the diffraction efficiency does not fall. As the holographic polymer film is manufactured using roll‐to‐roll techniques, although still in a laboratory scale in this study, it has a strong possibility of being manufactured in larger sizes with lower cost.