Masakazu Nishida

Detoxification of Bisphenol A and Nonylphenol by Purified Extracellular Laccase from a Fungus Isolated from Soil

Purified laccase from a fungus (family Chaetomiaceae) was used for the enzymatic oxidation of bisphenol A and nonylphenol, endocrine-disrupting chemicals. It rapidly oxidized both chemicals in the absence of mediators and within 24 h their estrogenic activities were completely removed.

Synthesis and characterization of dense SnP2O7–SnO2 composite ceramics as intermediate-temperature proton conductors

Dense SnP2O7–SnO2 composite ceramics were prepared by reacting a porous SnO2 substrate with an 85% H3PO4 solution at elevated temperatures. At 300 °C and higher, SnO2 reacted with H3PO4 to form an SnP2O7 layer on exterior and interior surfaces in the substrate, the growth rate of which increased with increasing reaction temperature. Finally, at 600 °C, the pores of this composite ceramic were perfectly closed and its electrical conductivity became several orders of magnitude higher than that of the SnO2 substrate alone. Proton conduction was demonstrated in this composite ceramic using electrochemical measurements and various analytical techniques. Comparison of the observed electromotive force with the theoretical value in two gas concentration cells demonstrated that this composite ceramic is a pure ion conductor, wherein the predominant ion species are protons. Fourier transform infrared (FT-IR) and proton magic angle spinning (MAS) nuclear magnetic resonance (NMR) analyses revealed that the protons interacted with lattice oxide ions in the SnP2O7 layer to form hydrogen bonds. An H/D isotope effect suggested that proton conduction in this composite ceramic was based on a proton-hopping mechanism. The proton conductivity in this material reached ∼10−2 S cm−1 in the temperature range of 250–600 °C.

Hydroxide Ion Conducting Antimony(V)‐Doped Tin Pyrophosphate Electrolyte for Intermediate‐Temperature Alkaline Fuel Cells

Alkaline fuel cells have received significant interest in recent years relative to acid fuel cells, because of advantages when operating under alkaline conditions, which include enhancement of the electrode reaction kinetics, especially at the cathode, as the cathode catalyst is not subjected to corrosion. Consequently, non-noble metals or inexpensive metal oxides can be used as catalysts. In addition, high energy density liquids and gases such as ethanol, hydrazine, and ammonia can be adopted as fuels. Anion exchange polymers are widely viewed as promising candidates for electrolyte membranes; however, a major challenge in the development of such polymers is their stability at high pH, because both the main chain and functional groups are easily degraded by hydroxide ion attacks. In addition, the poor chemical stability of current anion exchange polymers means that the operating temperature is limited to 80 8C or less; therefore, this type fuel cell is typically operated between 50 and 60 8C. Operating a fuel cell at elevated temperatures provides the anode catalyst with high tolerance to CO, which is useful for both acid and alkaline fuel cells. Additional benefits include small polarization loss, good drainage at the anode, and effective heat dissipation from the fuel cell system. A few anion-conducting electrolyte materials capable of operating at intermediate temperatures (100–200 8C) have been reported, such as KOH-doped polybenzimidazole (PBI) and hydroxide ion-intercalated Mg–Al layered double hydroxide (LDH). However, the reaction of KOH in the former electrolyte with CO2 present in the air to form K2CO3 is a possibility, and the hydroxide ion conductivity of the latter (0.03 S cm 1 at 200 8C) is not sufficiently high to achieve satisfactory cell performance. Further increases in chemical stability and conductivity would enhance the position of intermediate-temperature anion exchange membranes as the preferred electrolyte material for practical alkaline fuel cells. In this study, metal pyrophosphates (MP2O7) were studied as anion-conducting electrolytes for intermediate temperature applications. The metal pyrophosphate structure can be described as a network of MO6 octahedra sharing corners with P2O7 units, characterized by the presence of intersecting zigzag tunnels delimited by pentagonal windows. This unique crystalline structure provides many ion exchange sites and transport pathways. To date, proton exchange capability is typically introduced into the bulk of SnP2O7 by the partial substitution of Sn cations with low-valency cations, such as In, Al, Mg, Sb, Sc, Ga, and Zn. The resultant proton conductivity reaches approximately 0.1 Scm 1 at 200 8C. An opposite effect is expected by the partial substitution of Sn cations with high-valency cations, which would result in hydroxide ion exchange capability because of charge compensation for the high-valency cations. We demonstrate the hydroxide ion conduction of pentavalent cation-doped SnP2O7 at intermediate temperatures using electrochemical measurements, including complex impedance, gas concentration cells, and H/D isotope replacement methods. Moreover, Sn0.92Sb0.08P2O7, which exhibits the highest hydroxide ion conductivity among the tested compounds, is characterized with respect to the hydroxide ion environment and the basicity of the compound. In addition, fuel cell tests with the Sn0.92Sb0.08P2O7 electrolyte were conducted in the temperature range of 50–200 8C. The crystalline structure of Sb-doped SnP2O7 as an example of Sn1–xAxP2O7 (A V = pentavalent cation dopants) was identified using X-ray diffraction (XRD) measurement (see Figure S1 in the Supporting Information). The XRD pattern of the nondoped sample was assigned to SnP2O7 (72 mol %) and SnO2 (28 mol%). Tao interpreted the presence of the SnO2 phase to be due to the use of large SnO2 particles as a raw material, which causes the formation of a core–shell structure, although such a structure could not be determined from transmission electron microscopy (TEM) measurements (see Figure S2 in the Supporting Information). (The content of SnO2, which has a negative effect on ionic conduction, can be reduced when smaller SnO2 particles are used as a raw material.) Sn1–xSbxP2O7 with an Sb 5+ content of not more than 8 mol% had the same pattern as that of the nondoped sample. The peaks attributable to SnP2O7 were shifted slightly toward higher Bragg angles by an increase in the Sb content, which is expected with substitution of Sn (0.69 ) with Sb (0.60 ) of a smaller ionic radius. As a consequence, the lattice constant of SnP2O7 decreased from 7.925 to 7.916 with increasing Sb content from zero to 8 mol%. In contrast, Sn1–xSbxP2O7 with an Sb 5+ content of 10 mol% or higher contained some peaks attributable to Sn2.5P3O12, which indicates that 8 mol% Sb 5+ is the substitution limit. The temperature dependency of the electrical conductivity for Sn1–xSbxP2O7 was measured in air saturated with H2O vapor at 50 8C (Figure 1) and revealed two common features. [*] Prof. Dr. T. Hibino, Dr. Y. Shen, Dr. M. Nagao Graduate School of Environmental Studies, Nagoya University Nagoya 464-8601 (Japan) E-mail: hibino@urban.env.nagoya-u.ac.jp

Parallel factor (PARAFAC) kernel analysis of temperature- and composition- dependent NMR spectra of poly(lactic acid) nanocomposites

The parallel factor (PARAFAC) kernel matrix to analyze a sample system stimulated by more than one type of perturbation is described. PARAFAC kernel is a quantitative representation of the synchronicity and asynchronicity observed within the PARAFAC score matrices generated by carrying out two-dimensional (2D) correlation analyses. Thus, kernel matrix representation provides more intuitively understandable interpretation to the conventional PARAFAC trilinear model. In this study, the utility of PARAFAC kernel is demonstrated by the study of poly(lactic acid)-nanocomposite undergoing a structural change depending on the temperature as well as the clay content in the sample. Seemingly complicated variation of nuclear magnetic resonance (NMR) spectra induced by the change in the temperature and clay content are readily analyzed by the multiple-perturbation 2D correlation spectroscopy and PARAFAC kernel. PARAFAC kernel revealed that crystalline and amorphous structures of the PLA substantially undergo thermal deformation, and these variations are also influenced by the presence of the clay.

Proton conduction in AIII0.5BV0.5P2O7 compounds at intermediate temperatures

Proton conductors capable of operation between 100 and 400 °C are attractive electrochemical materials due to their high utility value in energy and environmental applications. However, such proton conductors have not yet made headway in the marketplace, due to insufficient proton conductivity. Here, we present new types of metal pyrophosphates as promising candidates for intermediate temperature proton conductors. A series of AIII0.5BV0.5P2O7 (AIIIBV = InSb, SbSb, FeSb, GaNb, FeNb, YNb, GaTa, AlTa, FeTa, YTa, BiTa, and SmTa) compounds were synthesized, of which In0.5Sb0.5P2O7, Fe0.5Nb0.5P2O7, and Fe0.5Ta0.5P2O7 exhibited the highest proton conductivities in the temperature ranges of 50–100 °C (0.045 S cm−1@100 °C), 100–200 °C (0.12 S cm−1@150 °C), and 200–400 °C (0.18 S cm−1@250 °C), respectively, in unhumidified air. The proton conductivity of these three compounds was further enhanced by the introduction of AIII or BV deficiency into the bulk. Consequently, Fe0.4Ta0.5P2O7 exhibited the highest proton conductivity of 0.27 S cm−1 at 300 °C in unhumidified air. Such high proton conductivity values were also observed under fuel cell operating conditions. The environments of protons in the bulk of these compounds were monitored using Fourier transform infrared (FT-IR) spectroscopy, temperature-programmed desorption (TPD), and proton magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. Protons were incorporated into the compounds for charge-compensation of the deficient AIII or BV cations, which results in an increase in the quantity of protons. More importantly, the mobility of the protons was also enhanced. Various electrochemical measurements demonstrate that proton conduction is dominant in these compounds, where the protons migrate according to a hopping mechanism.

Proton-Conducting Thin Film Grown on Yttria-Stabilized Zirconia Surface for Ammonia Gas Sensing Technologies

We demonstrate an approach to impart both proton conduction and solid acidity to the surface of yttria-stabilized zirconia (YSZ). By reacting a YSZ substrate with liquid H 3 PO 4 at 500°C, a thin Zr 1-x Y x P 2 O 7 film is grown on the substrate, which shows proton conductivity dependence on humidity and strong acid sites interacting with basic ammonia gas. This technique can be applied to gas sensor devices, yielding a remarkably sensitive and selective response to low concentrations (parts per million) of ammonia. Another important achievement of this technique is the realization of sensing properties in spite of using a conventional Pt electrode.

Preparation of perfluoro-1,3-propanedisulfonic acid/silica nanocomposites-encapsulated low molecular weight aromatic compounds possessing a nonflammable characteristic

Perfluoro-1,3-propanedisulfonic acid/silica [PFPS/SiO(2)] nanocomposites were prepared by the sol-gel reactions of the corresponding disulfonic acid [PFPS] with tetraethoxysilane and silica nanoparticles under alkaline conditions. These fluorinated nanocomposites thus obtained can exhibit no weight loss behavior corresponding to the contents of PFPS in the composites after calcination at 800°C, although the parent PFPS can decompose completely around 270°C. In addition, we succeeded in encapsulation of a variety of low molecular weight aromatic compounds such as bisphenol-A, bisphenol-AF, bisphenol-F, 4,4-biphenol and 1,1-bi-2-naphthol into PFPS/SiO(2) nanocomposite cores. (1)H MAS NMR spectra, UV-vis spectra, fluorescence spectra and HPLC measurements of PFPS/SiO(2) nanocomposites-encapsulated bisphenol-A showed the presence of encapsulated bisphenol-A in the composites before and even after calcination at 800°C. Interestingly, it was verified that fluorescence spectra of PFPS/SiO(2) nanocomposites-encapsulated bisphenol-A after calcination at 800°C can exhibit an extremely red-shifted and enhanced fluorescence peak, compared to that before calcination or parent bisphenol-A.

Instrumental analyses of nanostructures and interactions with water molecules of biomass constituents of Japanese cypress

Nanostructures consisting of the biomass constituents of the denatured Japanese cypress (Chamaecyparis obtusa) were examined by instrumental analyses at multiple hierarchical levels. Delignification with NaClO2 solution smoothly proceeded to reveal a distorted cell by scanning electron microscopy; however, a trace amount of lignin still remained in the delignified sample according to attenuated total reflection infrared spectra (ATR-IR). Although hemicellulose could be removed by a treatment with NaOH solution, thermogravimetric analysis and 13C cross-polarization/magic angle spinning (CP-MAS) NMR showed a certain amount of hemicellulose remaining. Reaction of the delignified sample with NaOH solution produced a shrunken cell wall that consisted of cellulose with small amounts of lignin and hemicellulose, which were detected by ATR-IR and 13C CP-MAS NMR, respectively. These samples from which lignin and/or hemicellulose had been removed easily released water molecules, producing a decrease in the 1H signal intensity and longer 1H spin–lattice relaxation time (T1H) values in variable temperature 1H MAS NMR. The T1H values provided information about nano-scale molecular interaction difficult to obtain by other instrumental analyses and they greatly changed depending on the water content and ratio of the biomass constituents. The spin–lattice relaxation of all samples occurred via water molecules under humid conditions that provided sufficient water. Under heat-dried conditions, the spin–lattice relaxation mainly occurred via lignin for the samples with lignin remaining while it occurred via cellulose/hemicellulose for the samples without lignin. The variable temperature T1H analysis indicated that predominant spin–lattice relaxation route via lignin was caused by higher molecular mobility of lignin-containing samples compared with lignin-free samples.

Biphenylene units possessing flammable and nonflammable characteristics in fluoroalkyl end-capped vinyltrimethoxysilane oligomeric silica gel matrices after calcination at 800 °C

AbstractTwo kinds of fluoroalkyl end-capped vinyltrimethoxysilane oligomer [RF-(VM)n-RF] silica nanocomposites containing biphenylene units were prepared by the sol-gel reactions of the corresponding oligomer with biphenylene-bridged ethoxysilanes or 4,4′-biphenol under alkaline conditions, respectively. One is the fluorinated oligomer/silica nanocomposites containing biphenylene units [RF-(VM-SiO2)n–RF/Ar-SiO2], of whose biphenylene units were incorporated into nanocomposite cores through the siloxane bondings, and the other is the fluorinated oligomer/silica nanocomposites containing biphenylene units [RF-(VM-SiO2)n–RF/Biphenol], of whose biphenylene units were directly encapsulated into nanocomposite cores through the sol–gel process. Interestingly, the shape of RF-(VM-SiO2)n–RF/Ar-SiO2 nanocomposites is morphologically controlled cubic particles; although the shape of RF-(VM-SiO2)n–RF/Biphenol nanocomposites is spherically fine particles. Thermogravimetric analyses 2H magic-angle spinning nuclear magnetic resonance, Ultraviolet visible, and fluorescent spectra showed that biphenylene units in RF-(VM-SiO2)n–RF/Ar-SiO2 nanocomposites have a flammable characteristic after calcinations at 800xa0°C; in contrast, biphenylene units in RF-(VM-SiO2)n–RF/Biphenol nanocomposites have a nonflammable characteristic even after calcination at 800xa0°C. X-ray photoelectron spectroscopy analyses of these two kinds of fluorinated nanocomposites showed that nonflammable characteristic toward biphenylene units in the silica gel matrices is due to the formation of ammonium hexafluorosilicate during the sol–gel process.n FigureBiphenylene Units Possessing Flammable and Non-flammable Characteristics in Flurinated Silica Gel Matrices

Partially Proton-Exchanged WP2O7 with High Conductivity at Intermediate Temperatures

Proton conduction is reported in partially proton-exchanged WP 2 O 7 at intermediate temperatures. Electrochemical measurements demonstrated that proton conduction occurs in this material. Proton magic angle spinning nuclear magnetic resonance and Fourier transform IR analyses revealed that the ion-exchanged protons interact with the lattice oxide ions in WP 2 O 7 to form hydrogen bonds. The H/D isotope effect suggests that proton conduction in this material is based on the hopping mechanism. Consequently, the electrical conductivity of this material reached 1.1 x 10 -3 S cm -1 at 250°C and 1.7 × 10 -2 S cm -1 at 500°C.