• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.29 no.2
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• pp.83-90
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• 1997

An unbleached hardwood kraft pulp was bleached in vitro with partially purified manganese peroxidase (MnP) from the fungus Phanerochaete sordida YK-624 without the addition of MnSO$_4$ in the presence of oxalate, malonate or gluconate known as manganese chelator, When the pulp was treated without the addition of MnSO$_4$, the pulp brightness increased by about 10 points in the presence of 2 mM oxalate, but the brightness did not significantly increase in the presence of 50 mM malonate. Residual MnP activity decreased faster during the bleaching with MnP without MnSO$_4$ in the presence of malonate than in the presence of oxalate. Oxalate reduced MnO$_2$ which already existed in the pulp or was produced from $Mn^{2+}$ by oxidation with MnP and thus supplied $Mn^{2+}$ to the MnP system. Thus, bleaching of hardwood kraft pulp with MnP, using manganese originally existing in the pulp, became possible in the presence of oxalate, a good manganese chelator and reducing reagent. Properties of partially purified MnPs from liquid cultures of white rot fungi, Ganoderma sp. YK-505, Phanerochaete sordida YK-624 and Phanerochaete chrysosporium were compared. MnP from Ganoderma sp. YK-505 was superior to MnPs from P. sordida YK-624 and P. chrysosporium in stabilities against high temperature and high concentration of $H_2O$$_2$. The MnP from Ganoderma sp. YK-505 differed in pH-activity profile from other MnPs. These data suggest that MnP from Ganoderma sp. YK-505 has different structure from those of other fungi. Bleaching of hardwood kraft pulp using the MnP from ganoderma sp. YK-505 is now in progress.

• Journal of the Korean Wood Science and Technology
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• v.35 no.2
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• pp.85-95
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• 2007

Manganese dependent peroxidase (MnP) is the most ubiquitous enzyme produced by white-rot fungi, MnP is known to be involved in lignin degradation, biobleaching and oxidation of hazardous organopollutants. Bjerkandera fumosa is a nitrogen-unregulated white-rot fungus, which produces high amounts of MnP in the excess of N-nutrients due to increased biomass yield. The objective of this study was to optimize the MnP production in N-sufficient cultures by varying different physiological factors such as Mn concentration, culture pH, and incubation temperature. The growth of fungus was optimal in pH 4.5 at $30^{\circ}C$, $N_2$-unregulated white-rot fungus produces high amounts of MnP in the excess N-nutrients. The fungus produced the highest level of MnP (up to $1000U/{\ell}$) with $0.25g/{\ell}$ asparagine and $1g/{\ell}$ $NH_4Cl$ as N source at 1.5 mM $MnCl_2$ concentration, pH value of 4.5 at $30^{\circ}C$. Purification of MnP revealed the existence of two isoforms: MnPl and MnP2. The molecular masses of the purified MnPl and MnP2 were in the same range of 42~45 kDa. These isoforms of B. fumosa strictly require Mn to oxidize phenolic substrates. Concerned to kinetic constants of B. fumosa MnPs, B. fumosa has similar Km value and Vmax compared to the other white-rot fungi.

• Journal of the Korean Wood Science and Technology
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• v.27 no.2
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• pp.53-61
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• 1999

Effects of culture conditions and Mn(II) addition were investigated for production of extracellular manganese peroxidase by lignin-degrading fungus LSK-27, Nitrogen source was shown to more influence the production of extracellular manganese peroxidase by LSK-27 than carbon source. When peptone or yeast extract as nitrogen source was added, high MnP activity was obtained. Especially, nitrogen-sufficient culture condition was effective in MnP activity, showing significantly increase up to 1.0% peptone concentration, but carbon-sufficient was not. Mn(II) was shown to strongly induce the MnP production in culture fluids of LSK-27. Increase of MnP actiyity was obeserved up to addition of 100ppm Mn(II), and over this Mn(II) concentration appeared to be inhibitory. The highest level of MnP activity was attained when Mn(II) was added after 2 day incubation.

• Journal of the Semiconductor & Display Technology
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• v.20 no.1
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• pp.12-17
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• 2021

The electronic and magnetic properties for Mn-adsorbed on the chalcopyrite (CH) AlGaP2 semiconductor are investigated by using first-principles FPLMTO method. The clean CH-AlGaP2 without adsorbed Mn is a p-type semiconductor with a direct band-gap. The Mn-adsorbed CH-AlGaP2 exhibits the ferromagnetic state. It is more energetically stable than the other magnetic ones. The interstitial site on P-terminated surface is more energetically favorable one than the Al/Ga-terminated surface, or the other adsorbing sites. In the case of Mn-adsorbed Al/Ga-terminated surface, it is induced a strong coupling between Mn-3d and neighboring P-3p electrons. The holes of partially unoccupied minority Mn-3d state and majority (or minority) Al-3p or P-3p state are induced. Thus a high magnetic moment of Mn is sustained by holes-mediated double-exchange coupling. It is noticeable that the semiconducting and half-metallic characteristics of CH-AlGaP2:Mn thin film is disappeared.

• Environmental Engineering Research
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• v.15 no.4
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• pp.183-190
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• 2010

Biogenic Mn oxides are expected to have great potential in the control of water pollution due to their high catalytic activity, although information on biological Mn oxidation is not currently sufficient. In this study, the growth of a Mn oxidizing microorganism, Pseudomonas putida MnB1, was examined, with the Mn oxides formed by this strain characterized. The growth of P. putida MnB1 was not significantly influenced by Mn(II), but showed a slightly decreased growth rate in the presence of Pb(II) and EE2, indicating their insignificant adsorption onto the cell surface. Mn oxides were formed by P. putida MnB1, but the liquid growth medium and resulting biogenic solids were poorly crystalline, nano-sized particles. Biogenic Mn oxidation by P. putida MnB1 followed Michaelis-Menten kinetics, with stoichiometric amounts of Mn oxides formed, which corresponded with the initial Mn(II) concentration. However, the formation of Mn oxides was inhibited at high initial Mn(II) concentration, suggesting mass transfer obstruction of Mn(II) due to the accumulation of Mn oxides on the extracellular layer. Mn oxidation by P. putida MnB1 was very sensitive to pH and temperature, showing sharp decreases in the Mn oxidation rates outside of the optimum ranges, i.e. pH 7.43-8.22 and around 20-$26^{\circ}C$.

• Journal of Soil and Groundwater Environment
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• v.13 no.3
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• pp.52-58
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• 2008

Mn-impregnated activated carbon (Mn-AC) prepared at different conditions was applied in the treatment of synthetic wastewater containing both organic and inorganic contaminants. Phenol and As(III) was used as the representative organic and inorganic contaminants, respectively. After evaluation of the physicochemical characteristic and stability of Mn-AC, oxidation of As(III) as well as adsorption of phenol by activated carbon(AC) and Mn-AC were investigated in a batch reactor. To investigate the stability of Mn-AC, dissolution of Mn from each Mn-AC was measured pH ranging from 2 to 4. Although Mn-AC was unstable at a strong acidic condition, the dissoluted Mn was below 3 ppm at pH 4. XRD analysis of Mn-AC indicated that the mineral type of the impregnated manganese was $Mn_2O_3$. From the simultaneous treatment of As(III) and phenol by AC and Mn-AC, As(III) oxidation by Mn-AC was greater than that by AC at lower pH, while the reverse order was observed at higher pH. After impregnation of Mn onto AC, 13% decrease of the surface area was observed, causing 8% reduction of phenol removal. Considering removal properties of As(III) and phenol, Mn-AC could be applied in the simultaneous treatment of wastewater contaminated with multi-contaminants.

• Korean Journal of Materials Research
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• v.30 no.12
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• pp.666-671
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• 2020

The electronic structure and magnetic properties of chalcopyrite (CH) AlGaAs2 with dopant Mn at 3.125 and 6.25 % concentrations are investigated using first-principles calculations. The CH AlGaAs2 alloy is a p-type semiconductor with a small band-gap. The AlGaAs2:Mn shows that the ferromagnetic (FM) state is the most energetically favorable one. The Mn-doped AlGaAs2 exhibits FM and strong half-metallic ground states.The spin polarized Al(Ga,Mn)As2 state (Al-rich system) is more stable than the (Al,Mn)GaAs2 state (Ga-rich system), which has a magnetic moment of 3.82mB/Mn. The interaction between Mn-3d and As-4p states at the Fermi level dominates the other states.The states at the Fermi level are mainlyAs-4p electrons, which mediate strong interaction between the Mn-3d and As-4p states. It is noticeable that the FM ordering of dopant Mn with high magnetic moment originates from the As(4p)-Mn(3d)-As(4p) hybridization, which is attributed to the partially unfilled As-4pbands. The high FM moment of Mn is due to the double-exchange mechanism mediated by valence-band holes.

• Journal of the Korean Wood Science and Technology
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• v.23 no.4
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• pp.27-32
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• 1995

To understand whether ligninolytic enzyme catalyze polymerization or depolymerization of the high molecular weight (HMW) lignin, the action of laccase and Mn-peroxidase (MnP) towards commercial ligninsulfonates (LS) was examined in various conditions of pH and cosubstrates. Polymerization occurred when LS was incubated with laccase at pH 6.0. In contrast, the high molecular weight portions were significant1y reduced at pH 4.5, especially when glucose was added. When LS was treated with MnP at pH 4.5, compounds of low molecular weight were produced. In particular, when cellobiose was added to Mn-P reaction mixture, the breakdown of LS was observed. In conclusion, degradation of LS by laccase and MnP occurred primarily at pH 4.5 where-as polymerization of LS was dominant at pH 6.0. Color index, however, was not greatly changed in the degradation mixtures of LS.

• Journal of Mushroom
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• v.11 no.2
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• pp.87-91
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• 2013

When No. 42 strain of Pleurotus ostreatus was cultivated at five different media, MnP and Lac but no LiP activity was detected throughout the culture period in the media. The production of MnP and Lac by No. 42 strain of Pleurotus ostreatus were correlated with wheat bran composition in the medium. In the liquid culture, maximum production of MnP and Lac were observed in the medium contained glucose-peptone- yeast-wheat bran(GPYW). However, in solid medium, maximum production of MnP was observed in wood meal-wheat bran(WMW) medium, but that of Lac was observed in wheat bran(W) medium.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.4
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• pp.423-429
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• 2008

Application of manganese-impregnated activated carbon(Mn-AC) in the treatment of synthetic wastewater containing both organic and inorganic contaminants was investigated. Phenol and As(III) was used as representative organic and inorganic contaminants, respectively. When the stability of Mn-AC at acidic condition was evaluated with variation of solution pH ranging from 2 to 4, Mn-AC was unstable below pH 3, while negligible dissolution of Mn was observed above pH 4. This stability test suggests a plausible applicability of Mn-AC in the treatment of wastewater above pH 4. Compared to AC-alone, the adsorption rates of phenol as well as adsorbed amounts of phenol by Mn-AC were slightly decreased due to the decrease of the surface area by impregnation. The maximum adsorbed amount of phenol by Mn-AC was corresponds to 75% of that by AC-alone from the adsorption isotherm study. The oxidation efficiency of As(III) by Mn-AC was greater than that by AC-alone at lower pHs while reverse trend was observed as pH increased above 7. From this work, it was found that Mn-AC could be used in the simultaneous treatment of both phenol and As(III).