Selective Oxidative Degradation of Organic Pollutants by Singlet Oxygen-Mediated Photosensitization: Tin Porphyrin versus C(60) Aminofullerene Systems

This study evaluates the potential application of tin porphyrin- and C(60) aminofullerene-derivatized silica (SnP/silica and aminoC(60)/silica) as (1)O(2) generating systems for photochemical degradation of organic pollutants. Photosensitized (1)O(2) production with SnP/silica, which was faster than with aminoC(60)/silica, effectively oxidized a variety of pharmaceuticals. Significant degradation of pharmaceuticals in the presence of the 400-nm UV cutoff filter corroborated visible light activation of both photosensitizers. Whereas the efficacy of aminoC(60)/silica for (1)O(2) production drastically decreased under irradiation with λ > 550 nm, Q-band absorption caused negligible loss of the photosensitizing activity of SnP/silica in the long wavelength region. Faster destruction of phenolates by SnP/silica and aminoC(60)/silica under alkaline pH conditions further implicated (1)O(2) involvement in the oxidative degradation. Direct charge transfer mediated by SnP, which was inferred from nanosecond laser flash photolysis, induced significant degradation of neutral phenols under high power light irradiation. Self-sensitized destruction caused gradual activity loss of SnP/silica in reuse tests unlike aminoC(60)/silica. The kinetic comparison of SnP/silica and TiO(2) photocatalyst in real wastewater effluents showed that photosensitized singlet oxygenation of pharmaceuticals was still efficiently achieved in the presence of background organic matters, while significant interference was observed for photocatalyzed oxidation involving non-selective OH radical.     

Wettability of liquid caesium iodine and boron oxide on yttria-stabilized zirconia

During the Fukushima Daiichi Nuclear Power Plant accident occurred in 2011, volatile fission products (FPs) such as Cs and I had released and caused environmental contamination and public exposure, respectively. However, the release mechanism of these FPs from fuels under the accident is still not completely understood. In recent years, we have focused on the wettability of liquid FPs against solid fuels, because the interface between the fuel surface and the FPs becomes the migration pathway, which might have large influences on the release behaviour of the FPs. Here, we studied the wettability of liquid CsI and B₂O₃ on yttria-stabilized zirconia (YSZ) solid surface by the sessile drop test, where YSZ is a simulated material of the fuel. It was revealed that liquid CsI exhibited extremely high wettability against the YSZ surface with the contact angle of nearly zero. This high wettability may act to suppress the FPs release. Furthermore, it was confirmed that the crystal orientation and surface roughness of the YSZ solids have large influences on the wettability of liquid B₂O₃. The present results contribute for deep understanding of the release behaviour of the volatile FPs from fuels.     

Synthesis of MDI and PCL-diol-based polyurethanes containing [2] and [3]rotaxanes and their properties

We have successfully synthesized novel polyurethanes where PU1 contains a [3]rotaxane that consists of N-3,5-di-tert-butylbenzyl-N-3-hydroxypropylammonium hexafluorophosphate (AOH1) and N,N′-Dimethyl-N,N′-bis(dibenzo-24-crown-8)-terephthalamide (BisC) as well as PU2 contains a [2]rotaxane that consists of AOH1 and dibenzo-24-crown-8 ether. Diphenylmethanediisocyanate (MDI), 1,4-butanediol (BD) and poly(ε-caprolactone)diol (PCL) were used as an isocyanate, chain expander, and soft segment, respectively. A polyurethane without any rotaxane structures (PU0) were also prepared as a reference polymer. The existence of the rotaxanes in the polyurethanes was confirmed by ¹H NMR spectroscopy and TGA measurement. ATR-FT-IR spectral measurement revealed that the rotaxanes disturb the formation of hydrogen bonding between the polyurethane chains. From the DSC result, the rotaxanes retard the recrystallization of the PCL unit whereas no influence on the glass transition temperatures of the polyurethanes was observed. The retarding effect appeared remarkably with PU1. These thermal behaviors of the polyurethanes were also supported by viscoelastic measurement. In tensile test, the tensile strength and break of strain of PU1 were larger than those of PU2.     

Total Synthesis and Structural Revision of Kasumigamide,and Identification of a New Analogue

Kasumigamide is an antialgal hybrid peptide–polyketide isolated from the freshwater cyanobacterium Microcystis aeruginosa (NIES-87). The biosynthetic gene cluster was identified from not only the cyanobacterium but also Candidatus “Entotheonella”, associated with the Japanese marine sponge Discodermia calyx. Therefore, kasumigamide is considered to play a key role in microbial ecology, regardless of the terrestrial and marine habitats. We now report synthetic studies on this intriguing natural product that have led to a structural revision and the first total synthesis. During this study, a new analogue, deoxykasumigamide, was also isolated and structurally validated. This study confirmed the presence of the unusual pathway in the biosynthesis of a hybrid peptide–polyketide natural product.     

Fast redox of composite electrode of nitroxide radical polymer and carbon with polyacrylate binder

For organic radical batteries, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) has been reported as a promising positive electrode material. The PTMA/C composite electrode prepared with polyacrylate binder demonstrated the fast redox performance for the application to aprotic secondary batteries. When the variation in discharge capacities of the PTMA/C composite electrode was tested galvanostatically at 20C rates, the electrode retained 96% of the initial capacity after 1000 cycles. This is attributed to the fact that the redox of PTMA is a simple reaction to form the oxoammonium salt doped with ClO₄^? anions in the electrolyte. When the PTMA/C composite electrode was discharged at different C rates, the electrode retained 81% of the theoretical capacity even at 50C rates. This remarkably high rate capability originates from the fast electron-transfer kinetic of the 2,2,6,6-tetramethylpiperidine-N-oxyl (so-called TEMPO) radical, partially jelled polyacrylate binder, and the improved conductivity throughout the electrode by thoroughly mixing with carbon.     

Structural analysis of oriented poly(ε‐caprolactone) including CaCO3 particles with 13C solid‐state NMR

The results of a study of the relation between the oriented structure and drawn Poly(ε‐caprolactone) specimens including CaCO₃ particles and their dynamic mechanical properties are presented. The loss elasticity, E″, showed almost the same curve for both undrawn sheets and drawn sheets as a function of CaCO₃ content. On the other hand, the storage modulus, E′, of drawn sheets increased nonlinearly with increasing CaCO₃ content, and their curve showed lower E′ values than those of undrawn sheets. By simulation of ¹³C CP NMR spectra of drawn PCL/CaCO₃ sheets, both oriented and unoriented components were observed. The distribution parameter, p, of drawn PCL/CaCO₃ sheets was 13°, which was larger than those (8°) of drawn PCL. Further, the fraction of the unoriented component increased with increasing CaCO₃ content. Thus, adding CaCO₃ particles into the PCL, the arrangement of the oriented component was disturbed and decreased. In addition, from the line shape analyses of ¹³C CP MAS NMR spectra, four peaks were obtained in not only undrawn sheets but also in drawn sheets of both PCL and PCL/CaCO₃ compounds. Besides, structural change occurred at only drawn PCL/CaCO₃ sheets. Therefore, the change in dynamic mechanical properties observed only for drawn PCL/CaCO₃ sheets were strongly dependent on the orientational structure, which was formed under shear stress of the stretching drawn process. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2376–2382, 2001     

A New Catalyst for Selective Oxidation of CO in H2: Part 1, Activation by Depositing a Large Amount of FeO x on Pt/Al2O3 and Pt/CeO2 Catalysts

1% Pt/Al₂O₃ and 1% Pt/CeO₂ are markedly activated by the deposition of a large quantity of FeO _x , about 100 wt% in Fe with respect to the supports. In contrast, the activity of a Ru/Al₂O₃ catalyst was completely suppressed by the deposition of FeO _x , but a Ru-Pt/Al₂O₃ was markedly activated by the FeO _x . The activation depends on the sequence of the deposition, that is, no pronounced activation was observed on the Pt supported on a FeO _x /Al₂O₃ as well as on the Pt codeposited with a small amount of Fe on Al₂O₃, that is, the activity was almost equal to that of the Pt/Al₂O₃. The XPS analysis of the Pt/CeO₂ and FeO _x /Pt/CeO₂ proved that the Pt is effectively covered with the FeO _x . Selectivity for the oxidation of CO in H₂ was also improved on the FeO _x /Pt/Al₂O₃ and FeO _x /Pt/CeO₂ catalysts and it is rather independent of the conversion. In conformity with the feature of the FeO _x /Pt/Al₂O₃ and FeO _x /Pt/CeO₂ catalysts, we deduced that the deposited FeO _x is activated by the Pt and the FeO _x is responsible for the selective oxidation of CO.     

Pressureless Sintering and Reaction Mechanisms of Ti3SiC2 Ceramics

Easy sinterable Ti₃SiC₂ powder was synthesized from a powder mixture with a molar ratio of 1.0 Ti, 0.3 Al, 1.2 Si, and 2.0 TiC by heating at 1200°C in the flowing Ar. Here, the Al powder acts as a deoxidation agent and provides a liquid phase for the reaction. The powder compacts subjected to pressureless sintering at 1300°C in Ar had a relative density up to 99%. The results of chemical analysis and the measured lattice constant suggest that the Al–Si liquid phase was formed at approximately 1200°C and that liquid‐phase sintering was promoted by the 0.1 molar ratio of Al and the 0.2 molar ratio of Si remaining in excess. The three‐point bending strength, fracture toughness, and electrical resistivity of the sintered samples were 380 MPa, 4.1 MPa m^1/2, and 0.34μΩm, respectively.     

Usefulness of myeloperoxidase as a biomarker for the ranking of pulmonary toxicity of nanomaterials

Background

In order to examine whether myeloperoxidase (MPO) can be a useful marker for evaluating the pulmonary toxicity of nanomaterials, we analyzed MPO protein in bronchoalveolar lavage fluid (BALF) samples obtained from previous examinations of a rat model. In those examinations we performed intratracheal instillation exposures (dose: 0.2–1.0 mg) and inhalation exposures (exposure concentration: 0.32–10.4 mg/m³) using 9 and 4 nanomaterials with different toxicities, respectively. Based on those previous studies, we set Nickel oxide nanoparticles (NiO), cerium dioxide nanoparticles (CeO₂), multi wall carbon nanotubes with short or long length (MWCNT (S) and MWCNT (L)), and single wall carbon nanotube (SWCNT) as chemicals with high toxicity; and titanium dioxide nanoparticles (TiO₂ (P90) and TiO₂ (Rutile)), zinc oxide nanoparticles (ZnO), and toner with external additives including nanoparticles as chemicals with low toxicity. We measured the concentration of MPO in BALF samples from rats from 3 days to 6 months following a single intratracheal instillation, and from 3 days to 3 months after the end of inhalation exposure.

Results

Intratracheal instillation of high toxicity NiO, CeO_2, MWCNT (S), MWCNT (L), and SWCNT persistently increased the concentration of MPO, and inhalation of NiO and CeO₂ increased the MPO in BALF. By contrast, intratracheal instillation of low toxicity TiO₂ (P90), TiO₂ (Rutile), ZnO, and toner increased the concentration of MPO in BALF only transiently, and inhalation of TiO₂ (Rutile) and ZnO induced almost no increase of the MPO. The concentration of MPO correlated with the number of total cells and neutrophils, the concentration of chemokines for neutrophils (cytokine-induced neutrophil chemoattractant (CINC)-1 and heme oxygenase (HO)-1), and the activity of released lactate dehydrogenase (LDH) in BALF. The results from the receiver operating characteristics (ROC) for the toxicity of chemicals by the concentration of MPO proteins in the intratracheal instillation and inhalation exposures showed that the largest areas under the curves (AUC) s in both examinations occurred at 1 month after exposure.

Conclusion

These data suggest that MPO can be a useful biomarker for the ranking of the pulmonary toxicity of nanomaterials, especially at 1 month after exposure, in both intratracheal instillation and inhalation exposure.