Mn‐peroxidase production by Panus tigrinus CBS 577.79: response surface optimisation and bioreactor comparison

This study reports the statistical optimisation through response surface methodology of the growth medium for Panus tigrinus manganese‐dependent peroxidase (MnP) production in shaken culture. Three crucial variables, including carbon source, malonic acid and Mn²⁺, were optimised in a nitrogen‐limited medium. Sucrose was the best carbon source for MnP production. Mn²⁺ ions and malonic acid significantly stimulated MnP production at an optimal concentration of 53 mg dm^?3 and 8.2 mmol dm^?3, respectively, resulting in 0.83 U cm^?3. Further experiments were performed in lab‐scale stirred tank (STR) and bubble‐column (BCR) reactors using the previously optimised liquid medium. BCR proved to be more adequate than STR in supporting MnP production, leading to 3700 U dm^?3 after 144 h with a productivity of 25.7 U dm^?3 h^?1. On a comparative basis with other production data in lab‐scale reactors, these results appear to be compatible with scale transfer. Copyright © 2006 Society of Chemical Industry     

A novel Mn4+‐activated red phosphor for use in light emitting diodes,K3SiF7:Mn4+

Phosphors that exhibit a narrow red emission are particularly interesting due to the advantage of providing a more extensive color gamut and better rendering in LED applications such as displays and solid‐state lighting. Although some Eu²⁺‐activated nitridosilicates have been discovered in this regard, K₂SiF₆:Mn⁴⁺ phosphors are the only option in actual LED applications thus far. We discovered a novel phosphor, K₃SiF₇:Mn⁴⁺, with P4/mbm symmetry. The luminescent properties of K₃SiF₇:Mn⁴⁺ are almost identical to those of the K₂SiF₆:Mn⁴⁺ phosphor, but its materials identity is distinct due to a completely different crystallographic structure, which leads to reduced decay time. The fast decay is one of the most serious disadvantages of existing K₂SiF₆:Mn⁴⁺ phosphors. The K₃SiF₇:Mn⁴⁺ phosphor was examined in comparison to the K₂SiF₆:Mn⁴⁺ via density functional theory calculation, Rietveld refinement, X‐ray photoelectron spectroscopy, X‐ray absorption near‐edge structure spectroscopy, and time‐resolved photoluminescence.     

Oxidative coupling of 2,6‐dimethylphenol catalyzed by copper(II) complexes in aqueous solution

The oxidative coupling reaction of 2,6‐dimethylphenol (DMP) with H₂O₂ catalyzed by four copper(II) complexes was investigated in Tris‐HNO₃ buffer solution at 25°C. The kinetics of formation of diphenoquinone (DPQ, 4‐(3,5‐dimethyl‐4‐oxo‐2,5‐cyclohexadienylidene)‐2,6‐dimethyl‐2,5‐cyclohexadienone) from DMP was studied in detail. The kinetic parameters k₂ and K_m were obtained in the pH range of 6.0–9.0. The copper(II) complexes exhibited the optimal catalytic activity at around pH 7.0. The pH effect was reasonably explicated by the catalytic kinetic model suggested in this work. The catalytic mechanism was discussed. The deprotonized associated radical LCu^I(OH^?)‐^?OOH was suggested as the possible predominant species to oxidize DMP. The C? C and C? O coupling products were analyzed and the ratio of poly (2,6‐dimethyl‐1,4‐phenylene ether) (PPE) to DPQ was also evaluated. Both in weak acidic (pH < 6.5) and in alkaline aqueous solution (pH > 8) were suitable to the C? O coupling reaction in our catalytic systems. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of K2SiF6:Mn4+ Phosphor from SiO2 Powders via Redox Reaction in HF/KMnO4 Solution and Their Application in Warm‐White LED

In this article, we propose a facile method for synthesis of K₂SiF₆:Mn⁴⁺ phosphor and discuss its promising application in warm‐white light emitting diodes (LED). The K₂SiF₆:Mn⁴⁺ was synthesized from SiO₂ powders through redox reaction in HF/KMnO₄ solution. The optical properties of LEDs containing different ratios of K₂SiF₆:Mn⁴⁺ phosphor and commercial Ce³⁺‐doped garnets (YAG‐40) yellow–green phosphor were studied. A warm‐white LED, with color temperature of 3510 K and color rendering index of 90.9 and efficacy of 81.56 lm/W was demonstrated.     

Preparation and Luminescence Properties of Eu2+ and Mn2+ Coactivated Tricalcium Phosphate Phosphors

Eu²⁺ and Mn²⁺ coactivated β–Ca₃(PO₄)₂ (TCP) phosphors have been prepared by high‐temperature solid‐state reaction. The site occupation and photoluminescence properties of Eu²⁺ and Mn²⁺ have been identified and discussed in detail. The energy transfer from Eu²⁺ to Mn²⁺ in TCP: Eu²⁺, Mn²⁺ phosphors has been validated and demonstrated to be a resonant type via a dipole‐quadrupole mechanism, and the critical distance (R_C) calculated by concentration quenching method is 21.76 Å. A color‐tunable emission from violet‐blue to red in TCP: Eu²⁺, Mn²⁺ phosphors can be realized via the energy transfer from Eu²⁺ to Mn²⁺ ions.     

Trametes versicolor laccase immobilized poly(glycidyl methacrylate) based cryogels for phenol degradation from aqueous media

This study aims removal of phenols in wastewater by enzymatic oxidation method. In this study, Trametes versicolor laccase was covalently immobilized onto a cryogel matrix by the nucleophilic attack of amino groups of laccase to epoxy groups of matrix. Glycidyl methacrylate was chosen as functional monomer to prepare poly(2‐hydroxyethyl methacrylate‐co‐glycidyl methacrylate) [p(HEMA‐co‐GMA)] cryogels. The enzyme immobilized matrix was characterized by FTIR, SEM, and swelling tests. The effect of pH, reaction time, temperature, substrate concentration, enzyme concentration, and storage period on immobilized enzyme activity was determined and compared with those of free enzyme. The model substrate was 2,2′‐azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS). Lineweaver‐Burk plots were used to calculate K_m and V_m values. K_m values were 165.1 and 156.0 µM while V_m values were 55.2 µM min^?1 and 1.57 µM min^?1 for free and immobilized laccase, respectively. Immobilized enzyme was determined to retain 82.5% and 72.0% of the original activity, respectively, after 6 consecutive use and storage period of 4 weeks. The free enzyme retained only 24.0% of its original activity following the same storage period. Lastly, decomposition products resulting from enzymatic oxidation of a model phenolic compound (3,5‐dinitrosalicylic acid) in aqueous solution were identified by liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41981.     

Immobilization of Pycnoporus sanguineus laccase by metal affinity adsorption on magnetic chelator particles

BACKGROUND: Immobilized enzymes provide many advantages over free enzymes including repeated or continuous reuse, easy separation of the product from reaction media, easy recovery of the enzyme, and improvement in enzyme stability. In order to improve catalytic activity of laccase and increase its industrial application, there is great interest in developing novel technologies on laccase immobilization. RESULTS: Magnetic Cu²⁺‐chelated particles, prepared by cerium‐initiated graft polymerization of tentacle‐type polymer chains with iminodiacetic acid (IDA) as chelating ligand, were employed for Pycnoporus sanguineus laccase immobilization. The particles showed an obvious high adsorption capacity of laccase (94.1 mg g^?1 support) with an activity recovery of 68.0% after immobilization. The laccase exhibited improved stability in reaction conditions over a broad temperature range between 45 °C and 70 °C and an optimal pH value of 3.0 after being adsorbed on the magnetic metal‐chelated particles. The value of the Michaelis constant (K_m) of the immobilized laccase (1.597 mmol L^?1) was higher than that of the free one (0.761 mmol L^?1), whereas the maximum velocity (V_max) was lower for the adsorbed laccase. Storage stability and temperature endurance of the immobilized laccase were found to increase greatly, and the immobilized laccase retained 87.8% of its initial activity after 10 successive batch reactions. CONCLUSION: The immobilized laccase not only can be operated magnetically, but also exhibits remarkably improved catalytic capacity and stability properties for various parameters, such as pH, temperature, reuse, and storage time, which can provide economic advantages for large‐scale biotechnological applications of laccase. Copyright © 2007 Society of Chemical Industry     

Tuning Mn4+ Red Photoluminescence in (K,Rb)2Ge4O9:Mn4+ Solid Solutions by Partial Alkali Substitution

We report on intense photoluminescence from materials of the (Rb,K)₂Ge₄O₉:Mn⁴⁺ solid solution as a novel class of red‐emitting oxide phosphors. In these compounds, luminescence originates from a virtually ideal substitution of Mn⁴⁺ for Ge⁴⁺ on octahedral lattice sites which are well‐isolated from each other within the unit cell by intermediate GeO₄ species. Complete isostructural substitution of K for Rb is possible across the join. The associated slight shrinkage of the unit cell has only little effect on the apparent Mn⁴⁺ interionic distance, but enables tuning of the absorption cross section and of the band structure, hence, of the emission lifetime, of the excitation band shape, and of emission quantum yield. Partial substitution was also found to reduce thermal quenching of the Mn⁴⁺‐related emission, apparently due to the lower polarizability of the K⁺ ion. In addition, random substitution of Rb by K enables modulation of the interaction of Mn⁴⁺ with its surrounding field at lower symmetry, leading to increasing emission bandwidth, i.e., 595 cm^?1 in K_1.5Rb_0.5Ge₄O₉:Mn⁴⁺ vs 558 or 578 cm^?1 in Rb₂Ge₄O₉:Mn⁴⁺ or K₂Ge₄O₉:Mn⁴⁺ respectively.     

Orderly‐Layered Tetravalent Manganese‐Doped Strontium Aluminate Sr4Al14O25:Mn4+: An Efficient Red Phosphor for Warm White Light Emitting Diodes

Searching for an efficient non rare earth‐based oxide red phosphor, particularly excitable by light in the wavelength from 380 to 480 nm and unexcitable by green light, is essential for the development of warm white light emitting diodes (WLEDs). Here, we report a promising and orderly‐layered candidate: Sr₄Al₁₄O₂₅:Mn⁴⁺ with CIE color coordinates (0.722, 0.278). It has higher luminescence efficiency particularly upon blue excitation and is much cheaper than the commercial red phosphor 3.5MgO·0.5MgF₂·GeO₂:Mn⁴⁺ (MMG:Mn⁴⁺). In sharp contrast to Eu²⁺‐doped (oxy)nitrides, the phosphor can be synthesized by a standard solid‐state reaction at 1200°C in air. The effects of flux boron content, environment, and preparation temperature, sintering dwelling time as well as Mn concentration have been systematically investigated for establishing the optimal synthesis conditions. The low temperature emission spectra reveal that there are at least three types of Mn⁴⁺ ions in Sr₄Al₁₄O₂₅:Mn⁴⁺ due to the substitution for the distorted octahedral Al³⁺ sites. The AlO₆ layers where Mn⁴⁺ prefers to reside are well separated from one another by AlO₄ tetrahedra in one dimension parallel to axis a. This scenario can efficiently isolate Mn⁴⁺ ions from local perturbations, thereby enabling the high efficiency of luminescence. The energy transfer rates and mechanism are discussed.     

New Insights into the Biosynthesis of Prenylated Xanthones: Xptb from Aspergillus nidulans Catalyses an O‐Prenylation of Xanthones

Gene‐inactivation experiments have indicated that the putative prenyltransferase XptB from Aspergillus nidulans was likely to be responsible for the prenylation of 1,7‐dihydroxy‐6‐methyl‐8‐hydroxymethylxanthone. Recently, it was suggested that this enzyme might also accept as substrate the benzophenone arugosin H, which is assumed to be a precursor of prenylated xanthones. In this study, five benzophenones and ten xanthones were incubated with purified recombinant XptB in the presence of dimethylallyl diphosphate (DMAPP). XptB accepted four xanthones as substrates, including the proposed natural substrate, and catalysed regiospecific O‐prenylations at C‐7 of the xanthone core. K_m values in the range of 0.081–1.1 mM and turnover numbers (k_cat) between 0.02 and 0.5 s^?1 were determined for the accepted xanthones. The kinetic parameters for DMAPP were found to be 0.024 mM (K_m) and 0.13 s^?1 (k_cat). Arugosin H was not accepted by XptB under the tested conditions. XptB was relatively specific towards its prenyl donor and did not accept geranyl or farnesyl diphosphate as substrate. Mn²⁺ and Co²⁺ strongly enhanced XptB activity (up to eightfold); this has not been reported before for prenyltransferases of the DMATS superfamily.     

Tunable Color of Eu2+/Mn2+ Coactivated Na5Ca2Al(PO4)4 via Energy Transfer

Eu²⁺ and Eu²⁺/Mn²⁺‐activated Na₅Ca₂Al(PO₄)₄ phosphors have been synthesized by the combustion method. X‐ray powder diffraction profiles, luminescence spectra, chromaticity variation, and energy transfer of Na₅Ca₂Al(PO₄)₄:Eu²⁺, Mn²⁺ were investigated as a function of the Eu²⁺ and Mn²⁺ concentrations in Na₅Ca₂Al(PO₄)₄. The Na₅Ca₂Al(PO₄)₄:Eu²⁺,Mn²⁺ phosphors can be effectively excited at wavelength ranging from 300 to 430 nm, which matches well with that for near‐ultraviolet (UV) light‐emitting diode (LED) chips. Under excitation at 354 nm, Na₅Ca₂Al(PO₄)₄:Eu²⁺,Mn²⁺ not only exhibits blue‐green emission band attributed to 4f⁶5d¹→4f⁷ of Eu²⁺ but also gives an orange emission band attributed to ⁴T₁→⁶A₁ of Mn²⁺. The emission color of the phosphor can be systematically tuned from blue‐green through white and eventually to orange by adjusting the relative content of Eu²⁺ and Mn²⁺ through the principle of energy transfer. The results indicated that Na₅Ca₂Al(PO₄)₄:Eu²⁺, Mn²⁺ may serve as a potential color‐tunable phosphor for near UV white‐light LED.     

Characterisation of deactivating agents and their influence on the stability of manganese‐dependent peroxidase from Phanerochaete chrysosporium

Production of manganese‐dependent peroxidase (MnP) by Phanerochaete chrysosporium in semi‐solid‐state cultures is described. The stability of MnP during the production stage and in the crude enzyme preparations was studied. Inactivation of MnP by various factors including proteases, hydrogen peroxide and pH value in semi‐solid‐state cultures on an inert support (nylon sponge) was studied. Strategies to avoid inactivation are described. Hydrogen peroxide was shown to be essential for enzyme deactivation. A method for the elimination of H₂O₂ based on catalase addition has been designed which resulted in improvement in both enzyme production and stability. © 2001 Society of Chemical Industry     

Optimized photoluminescence of red phosphor Na2SnF6:Mn4+ as red phosphor in the application in “warm” white LEDs

The Mn⁴⁺ activated fluostannate Na₂SnF₆ red phosphor was synthesized from starting materials metallic tin shots, NaF, and K₂MnF₆ in HF solution at room temperature by a two‐step method. The formation mechanism responsible for preparing Na₂SnF₆:Mn⁴⁺ (NSF:Mn) has been investigated. The influences of synthetic parameters: such as concentrations of HF and K₂MnF₆ in reaction system, reaction time, and temperature on crystallinity, microstructure, and luminescence intensity of NSF:Mn have been investigated based on detailed experimental results. The actual doping concentration of Mn⁴⁺ in the NSF:Mn host lattice is less than 0.12 mol%. The most of K₂MnF₆ is decomposed in HF solution especially in hydrothermal system at elevated temperatures. The color of the as‐prepared NSF:Mn samples changes from orange to white when the temperature is higher than 120°C, which indicates the lower concentration of luminescence centers in the crystals. A series of “warm” white light‐emitting diodes with color rendering index (CRI) higher than 88 and correlated color temperatures between 3146 and 5172 K were obtained by encapsulating the as‐prepared red phosphors NSF:Mn with yellow one Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce) on 450 nm blue InGaN chips. The advantage of the synthetic strategy to obtain NSF:Mn can be extended to developing Mn⁴⁺‐doped red phosphors from low‐costing metals at room temperature for large‐scale industrial applications.     

Purification and characterization of solvent‐tolerant,thermostable, alkaline metalloprotease from alkalophilic Pseudomonas aeruginosa MTCC 7926

BACKGROUND: Microbial proteases are becoming imperative for commercial applications. The protease secreted by Pseudomonas aeruginosa MTCC 7926, isolated from solvent‐contaminated habitat was purified and characterized for activity at various edaphic conditions. The purified alkaline protease was investigated for dehairing of animal skin, anti‐staphylococcal activity and processing of X‐ray film. RESULTS: The protease was 24‐fold purified by ammonium sulfate fractionation, sephadex G‐100 gel filtration and DEAE‐cellulose, with 36% recovery. K_M and V_max, using casein were 2.94 mg mL^?1 and 1.27 µmole min^?1, respectively. The apparent molecular mass by SDS‐PAGE was 35 kDa. Alkaline protease was active at pH 6–11 and temperature 25–65 °C. Its activity was (a) 86.8% in 100 mmol L^?1 NaCl, (b) >95% in metal ions (Mn²⁺, Ca²⁺, Mg²⁺, Fe²⁺) for 1 h, (c) >90% in bleaching agents and chemical surfactants, (d) 135.4 ± 2.0% and 119.9 ± 6.2% with rhamnolipid and cyclodextrin, respectively, (e) stable in solvents for 5–30 days at 27 °C, and (f) inhibited by EDTA, indicating metalloprotein. CONCLUSION: This work showed that purified protease retained its activity in surfactants, solvents, metals, and bleaching agents. The enzyme is an alternative for detergent formulations, dehairing of animal skin, X‐ray film processing, treatment of staphylococcal infections and possibly non‐aqueous enzymatic peptide synthesis. Copyright © 2009 Society of Chemical Industry     

Formation mechanism and optimized luminescence of Mn4+‐doped unequal dual‐alkaline hexafluorosilicate Li0.5Na1.5SiF6

A novel red phosphor Li_0.5Na_1.5SiF₆:Mn⁴⁺ (LNSF:Mn) based on the unequal dual‐alkaline hexafluorosilicate with superior optical performances has been synthesized via ion‐exchange between [MnF₆]^2? and [SiF₆]^2? at room temperature. The composition and the crystal structure of the as‐obtained phosphor LNSF:Mn were determined by energy‐dispersive x‐ray spectroscopy (EDS) and x‐ray diffraction (XRD), respectively. The formation mechanism of the red phosphor LNSF:Mn has been discussed in detail. The phosphor LNSF:Mn exhibits good chromaticity properties and a quantum yield (QY) of 96.1%, which are better than the identified fluorosilicate phosphors Na₂SiF₆:Mn⁴⁺ (NSF:Mn) and K₂SiF₆:Mn⁴⁺ (KSF:Mn). A broad and intense absorption in the blue and a bright emission in red‐shifted wavelengths make the phosphor LNSF:Mn a desired candidate for applications in warm white light‐emitting diodes.     

The Synthesis of New N2S2‐Macrocyclic Schiff Base Ligands and Investigation of Their Ion Extraction Capability from Aqueous Media

Abstract

Two new macrocyclic Schiff bases, (5) and (7), containing nitrogen‐sulfur donor atoms were designed and synthesized by reaction of α,α′ bis(o‐aminophenylthio)‐1,2‐xylene with glyoxal and phthaldialdehyde, respectively. The liquid‐liquid extraction of metal picrates such as Ag⁺, Hg²⁺, Cd²⁺, Zn²⁺, Cu²⁺, Ni²⁺, Mn²⁺, K⁺, and Na⁺ from aqueous phase to the organic phase was carried out using the novel ligands. The effect of chloroform and dichloromethane as organic solvents over the metal picrate extractions was investigated at 25±0.1°C by using UV‐visible spectrometry. The extractability and selectivity of the tested metal picrates were evaluated. The values of the extraction constants (log K_ex) were determined for the extracted complexes.     

Crystal structure and luminescence properties of a single‐component white‐light‐emitting phosphor Ca8ZnLa(PO4)7:Eu2+,Mn2+

A series of novel green emission Whitlockite‐type Ca₈ZnLa(PO₄)₇:Eu²⁺ and color tunable Ca₈ZnLa(PO₄)₇:Eu²⁺,Mn²⁺ phosphors were prepared by the solid‐state reaction method in a reducing atmosphere. Its crystal structure and phase composition were identified by high‐resolution transmission electron microscopy, selected area electronic diffraction, X‐ray photoelectron spectroscopy, and X‐ray powder diffraction Rietveld refinement, and it was found to be trigonal, belonging to R‐3c(161) space group. The luminescence properties of Eu²⁺ singly doped and Eu²⁺/Mn²⁺ codoped Ca₈ZnLa(PO₄)₇ phosphors were revealed in detail. Ca₈ZnLa(PO₄)₇:Eu²⁺ is excitable over a broad range from 200 to 450 nm with a prominent green emitting. With varied Eu²⁺/Mn²⁺ ratios, fine‐tune emission under 365 nm excitation can be achieved from green (0.221, 0.468) to magenta (0.391, 0.276), especially the warm white light (0.392, 0.352), and CCT 3500 K can be obtained by the process of energy transfer between Eu²⁺ and Mn²⁺. The ET mechanism in this system is managed via the dipole‐dipole interaction with the maximum energy‐transfer efficiency 82.8% based on the decay lifetime data. These results suggest that as‐prepared phosphors can serve as promising candidates of UV‐pumped w‐LEDs.     

Characteristics of poly(AAc5‐co‐HPMA3‐cl‐EGDMA15) hydrogel‐immobilized lipase of Pseudomonas aeruginosa MTCC‐4713

Four series of noble networks were synthesized with acrylic acid (AAc) copolymerized with varying amount of 2‐hydroxy propyl methacrylate or dodecyl methacrylate (AAc/HPMA or AAc/DMA; 5:1 to 5:5, w/w) in the presence of ethylene glycol dimethacrylate (EGDMA; 1, 5, 10, 15, and 20%, w/w) as a crosslinker and ammonium per sulfate (APS) as an initiator. Each of the networks was used to immobilize a purified lipase from Pseudomonas aeruginosa MTCC‐4713. The lipase was purified by successive salting out with (NH₄)₂SO₄, dialysis, and DEAE anion exchange chromatography. Two of the matrices, E_15a, i.e. [poly (AAc₅‐co‐DMA₁‐cl‐EGDMA₁₅)] and I_15c, i.e. [poly (AAc₅‐co‐HPMA₃‐cl‐EGDMA₁₅)], that showed relatively higher binding efficiency for lipase were selected for further studies. I_15c‐hydrogel retained 58.3% of its initial activity after 10th cycle of repetitive hydrolysis of p‐NPP, and I_15c was thus catalytically more stable and efficient than the other matrix. The I_15c‐hydrogel‐immobilized enzyme showed maximum activity at 65°C and pH 9.5. The hydrolytic activity of free and I_15c‐hydrogel‐immobilized enzyme increased profoundly in the presence of 5 mM chloride salts of Hg²⁺, NH₄⁺, Al³⁺, K⁺, and Fe³⁺. The immobilized lipase was preferentially active on medium chain length p‐nitrophenyl acyl ester (C:8, p‐nitrophenyl caprylate). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4636–4644, 2006     

Evaluation of basidiomycetous fungi for pretreatment of contaminated soil

BACKGROUND: For most dioxin‐contaminated sawmill soils, combustion is recommended. However, the process may be inefficient if the soil has a high organic matter content. The use of saprotrophic basidiomycetous fungi is an alternative for pretreatment of this kind of soil. A total of 147 fungi were evaluated for their ability to grow in sawmill soil. From this screening, the best soil colonizing fungi were selected to study their enzyme activities and degradation of soil organic matter. Pine (Pinus sylvestris) bark was used as a co‐substrate to propagate the fungi into the soil. The activities of manganese peroxidase (MnP), laccase, endo‐1,4‐β‐glucanase, endo‐1,4‐β‐xylanase, and endo‐1,4‐β‐mannanase were analysed from the inocula and fungal treated soil. RESULTS: The screening revealed that 56 out of 147 fungi were able to grow in non‐sterile soil, and most of them were litter‐decomposing fungi (LDF). In pine bark cultures, the highest enzyme activities were observed with Phanerochaete velutina, which produced 5 U g^?1 of MnP. The activity of endo‐1,4‐β‐glucanase was generally higher than that of other hydrolytic enzymes. The highest carbon loss from soil with a high organic matter content was achieved by P. velutina (3.4%) and Stropharia rugosoannulata (2.4%). CONCLUSIONS: Many LDF, and in addition the white‐rot fungus P. velutina, are potential degraders of soil organic matter since they showed good growth and respiratory activity. Pine bark was a suitable lignocellulosic co‐substrate and a good promoter of MnP activity. Copyright © 2009 Society of Chemical Industry     

Valence state and ionic conduction in Mn‐doped MgO partially stabilized zirconia

The mechanism of the enhancement in the ionic conductivity resulting from cubic phase stabilization in MgO partially stabilized zirconia (MgPSZ) by Mn doping was studied by examining the local Zr‐O structure. Cubic phase (14 vol%) in MgPSZ was increased with the addition of MnO₂, and 10 mol% Mn‐doped MgPSZ exhibited the highest cubic phase fraction (98.72%), which was analyzed by Rietveld refinement. In addition, only the cubic phase, not the monoclinic and tetragonal phases, was observed in the TEM‐SAED pattern of 10 mol% Mn‐doped MgPSZ. Doped Mn exhibited a high Mn²⁺/Mn⁴⁺ ratio, which was identified by X‐ray photoelectron spectroscopy (XPS). In addition, it indicates that oxygen vacancy formation by substitution of Mn²⁺ in the Zr⁴⁺ site in MgPSZ increased cubic phase fraction. Ionic conductivity of MgPSZ was improved by the cubic phase increase attributed to Mn doping, and 10 mol% Mn‐doped MgPSZ exhibited higher ionic conductivity than MgPSZ. To investigate the mechanism of the ionic conductivity improvement, Zr‐O local structure in Mn‐doped MgPSZ was analyzed by Zr K‐edge EXAFS of MgPSZ, and the number of bonding of the Zr‐O first shell decreased with increased Mn substitution. Therefore, it was considered that the oxygen vacancy generation led to an increase in the cubic phase and the number of ionic conduction sites.