• KSBB Journal
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• v.15 no.5
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• pp.444-451
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• 2000

Nonliving methanotrophic biomass was used as biosorbent to remove lead which is one of representative pollutants in metal-bearing wastewater. Solution pH, maximum uptake, biosorbent dose and ionic strength were considered as major factors for adsorption experiments. The optimum pH range for lead removal was increased 3.8∼11.0 for methanotrophic biomass compared to biosorbent-free control, pH of 8.4∼11.2. Removal efficiency of lead by methanotrophic biomass was pH dependent, but less sensitive than that of control. In isotherm experiments with 0.2g biosorbent/L at initial solution pH 5.0, methanotrophic biomass took up lead from aqueous solutions to the extent of 1085 mg/g biomass. Removal amount of lead increased with an increase of biomass dose. According to biomass dose for initial 1000 mg Pb/L at initial pH 5.0, the optimum amount of biomass for maximum lead removal per unit methanotrophic biomass was 0.2 g biomass/L. As a result of scanning electron microscope (SEM) micrographs equipped with energy dispersive spectroscopy (EDS), lead removal by methanotrophic biomass seemed to be through adsorptions on the surface of methanotrophic biomass and exopolymers around the biomass. EDS spectra confirmed that lead adsorption appeared on the biomass and exopolymers that may be effective to lead removal comparing before and after contact with lead. Removal efficiency of lead was slightly affected by ionic strength up to 2.0 M of NaCl and NaNO$_3$respectively.

• Journal of Environmental Health Sciences
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• v.33 no.2 s.95
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• pp.150-157
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• 2007

The chemical and photochemical decolorization of Rhodamine B (RhB) in water has been carried out by Fenton, Fenton-like and photo-Fenton-like process. The effect of applied $H_2O_2,\;Fe^{2+}$ dosage (Fenton process), $H_2O_2,\;Fe^{\circ}$ dosage (Fenton-like and photo-Fenton-like process), UV light power (photo-Fenton-like process) pH (all processes) have been studied. The results obtained showed that more than 98% of color removal was obtained for the RhB solutions in every process. However, Fenton-like process was not suitable for the color removal of RhB because Fenton-like process was required much more reagents than Fenton and photo-Fenton-like process. The Fenton and photo-Fenton-like process showed similar reagents need. Optimum pH for three processes in this study is about pH 3. The relative order of sensitivity for pH of each process was: Fenton-like > photo-Fenton-like > Fenton.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.207-215
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• 2014

Wastewater containing heavy metals such as copper (Cu) and nickel (Ni) is harmful to humans and the environment due to its high toxicity. Crystallization in a fluidized bed reactor (FBR) has recently received significant attention for heavy metal removal and recovery. It is necessary to find optimum reaction conditions to enhance crystallization efficacy. In this study, the effects of crystallization reagent and pH were investigated to maximize crystallization efficacy of Cu-S and Ni-S in a FBR. CaS and $Na_2S{\cdot}9H_2O$ were used as crystallization reagent, and pH were varied in the range of 1 to 7. Additionally, each optimum crystallization condition for Cu and Ni were sequentially employed in two FBRs for their selective removal from the mixture of Cu and Ni. As major results, the crystallization of Cu was most effective in the range of pH 1-2 for both CaS and $Na_2S{\cdot}9H_2O$ reagents. At pH 1, Cu was completely removed within five minutes. Ni showed a superior reactivity with S in $Na_2S{\cdot}9H_2O$ compared to that in CaS at pH 7. When applying each optimum crystallization condition sequentially, only Cu was firstly crystallized at pH 1 with CaS, and then, in the second FBR, the residual Ni was completely removed at pH 7 with $Na_2S{\cdot}9H_2O$. Each crystal recovered from two different FBRs was mainly composed of CuxSy and NiS, respectively. Our results revealed that Cu and Ni can be selectively recovered as reusable resources from the mixture by controlling pH and choosing crystallization reagent accordingly.

• ALGAE
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• v.21 no.3
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• pp.317-321
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• 2006

The effects pH and salinity on the brown alga Sargassum fulvellum were investigated in the context of the removal of two major associated animals, Caprella scaura and Gammaropsis utinomi. Optimum quantum yield (Fv/Fm) of S. fulvellum was also examined in the same experimental conditions as an index of stress. Experiments on pH and salinity tolerances of the two animal species indicated that mortality was more than 80% at extremes of pH (2, 3, 4, 10, 11, 12) and salinity (0, 3.5, 7, 10, 44 psu) after a 5 min treatment. Lethal time (LT50) from pH 2 to pH 4 was less than 90 sec in C. scaura, and less than 70 sec in G. utinomi. From 0 to 10 psu, LT50 was less than 20 sec in C. scaura and less than 60 sec in G. utinomi. The quantum yield of S. fulvellum was not significantly different from controls within the pH range 4~10, and within the salinity range of 7-40 psu. When exposed to pH and salinity conditions outside these ranges, the effect of these factors on the removal of two animal species was higher, but quantum yield was highly reduced. These results indicate that the optimal conditions for removing the animal species without affecting optimum quantum yield were pH 4-10, and salinities 7-10 psu and 44 psu.

• KSBB Journal
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• v.17 no.1
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• pp.14-19
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• 2002

The objective of this study is to investigate optimum condition for lignin peroxidase production by white rot fungi Phanerochaete chysosporium IFO 31249 immobilized in a rotating bioreactor. The maximum lignin peroxidase activity of batch culture in rotating bioreactor was 300 U/L. The optimum rotating speed and packing ratio of support for lignin peroxidase production in a rotating bioreactor were 1 rpm and 20%, respectively. The optimum concentration of $MnSO_4$$\cdot$$H_2O$ for manganese-dependent peroxidase production in a rotating bioreactor was 50 ppm. The sufficient supply of oxygen was the most important factor to achieve maximum lignin peroxidase production. It was possible to produce lignin peroxidase (LiP) and manganese-dependent peroxidase (MnP) for at least 3 times successive repeated-batch cultures, respectively.

• Communications for Statistical Applications and Methods
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• v.8 no.1
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• pp.147-151
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• 2001

In discrete red and black, you can stake any amount s in your possession, but the value of s takes positive integer value. Suppose your goal is N and your current fortune is f, with 0$\frac{1}{2}$ where the house has the advantage over the player, and with the value of p greater than $\frac{1}{2}$ where the player has the advantage over the house. The optimum strategy at any f when p<$\frac{1}{2}$ is to play boldly, which is to bet as much as you can. The optimum strategy when p>$\frac{1}{2}$ is to bet 1 all the time.

• Mycobiology
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• v.35 no.3
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• pp.135-144
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• 2007

The removal efficiency of the heavy metals Zn, Pb and Cd by the zoosporic fungal species Saprolegnia delica and the terrestrial fungus Trichoderma viride, isolated from polluted water drainages in the Delta of Nile in Egypt, as affected by various ranges of pH values and different temperature degrees, was extensively investigated. The maximum removal efficiency of S. delica for Zn(II) and Cd(II) was obtained at pH 8 and for Pb(II) was at pH 6 whilst the removal efficiency of T. viride was found to be optimum at pH 6 for the three applied heavy metals. Regardless the median lethal doses of the three heavy metals, Zn recorded the highest bioaccumulation potency by S. delica at all pH values except at pH 4, followed by Pb whereas Cd showed the lowest removal potency by the fungal species and vice versa in case of T. viride. The optimum bio-mass dry weight production by S. delica was found when the fungus was grown in the medium treated with the heavy metal Pb at pH 6, followed by Zn at pH 8 and Cd at pH 8. The optimum biomass dry weight yield by T. viride amended with Zn, Pb and Cd was obtained at pH 6 for the three heavy metals with the maximum value at Zn. The highest yield of biomass dry weight was found when T. viride treated with Cd at all different pH values followed by Pb whilst Zn output was the lowest and this result was reversed in case of S. delica. The maximum removal efficiency and the biomass dry weight production for the three tested heavy metals was obtained at the incubation temperature $20^{\circ}C$ in case of S. delica while it was $25^{\circ}C$ for T. viride. Incubation of T. viride at higher temperatures ($30^{\circ}C\;and\;35^{\circ}C$) enhanced the removal efficiency of Pb and Cd than low temperatures ($15^{\circ}C\;and\;20^{\circ}C$) and vice versa in case of Zn removal. At all tested incubation temperatures, the maximum yield of biomass dry weight was attained at Zn treatment by the two tested fungal species. The bioaccumulation potency of S. delica for Zn was higher than that for Pb at all temperature degrees of incubation and Cd bioaccumulation was the lowest whereas T. viride showed the highest removal efficiency for Pb followed by Cd and Zn was the minor of the heavy metals.

• Applied Biological Chemistry
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• v.10
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• pp.23-31
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• 1968

We have obtained the following results, at the production of cellulase of Chaetomium globosum and its properties of crude enzyme. 1. At the production of enzyme, wheat bran solid culture was more active than surface or shaking culture. 2. The production of enzyme was maximum between the eighth and the tenth days, but slightly decreased thereafter. 3. The optimum condition of the reactions in saccharification with CMC were obtained the following results. 1) The optimum pH was within the range of from 4.0 to 5.0 and stable pH range was within 3.5 to 6.5. 2) The optimum temperature was $40^{\circ}C$ and thermal stability was below $50^{\circ}C$ and completely inactivated at $70^{\circ}C$ 4 Dialyzed crude enzyme was activated by $Mn^{++}\;Mg^{++}\;Fe^{++}\;and\;Mo^{++}\;respectively\;but\;Hg^{++}$ was inhibited its enzyme action.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.704-711
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• 1994

Lipoxygenase of mackerel gill exhibited the highest reactivity toward eicosapentaenoic acid (EPA) followed by arachidonic acid, linoleic acid. The optimum pH were pH 4.5, 5.0 and 4.8 for EPA, arachidonic acid and linoleic acid, respectively. The enzyme was the most stable at pH 5.5. Optimum temperature was $25^{\circ}C$ for all substrate fatty acids. For linoleic and arachidonic acids the highest thermal stability was observed at $8^{\circ}C$ whereas, for (EPA) at $20^{\circ}C$. Optimum ionic strength was 0.22M, $Sn^{2+}$, vitamin E and catechin completely inhibited the enzyme at the concentration of 1.0mM. Molecular weight of the enzyme was 42,000 dalton.

• Journal of Microbiology and Biotechnology
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• v.24 no.6
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• pp.781-787
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• 2014

2-Ketogluconic acid production by Klebsiella pneumoniae is a pH-dependent process, strictly proceeding under acidic conditions. Unfortunately, cell growth is inhibited by acidic conditions, resulting in low productivity of 2-ketogluconic acid. To overcome this deficiency, a two-stage fermentation strategy was exploited in the current study. During the first stage, the culture was maintained at neutral pH, favoring cell growth. During the second stage, the culture pH was switched to acidic conditions favoring 2-ketogluconic acid accumulation. Culture parameters, including switching time, dissolved oxygen levels, pH, and temperature were optimized for the fed-batch fermentation. Characteristics of glucose dehydrogenase and gluconate dehydrogenase were revealed in vitro, and the optimal pHs of the two enzymes coincided with the optimum culture pH. Under optimum conditions, a total of 186 g/l 2-ketogluconic acid was produced at 26 h, and the conversion ratio was 0.98 mol/mol. This fermentation strategy has successfully overcome the mismatch between optimum parameters required for cell growth and 2-ketogluconic acid accumulation, and this result has the highest productivity and conversion ratio of 2-ketogluconic and produced by microorganism.