Characterization of microbial consortia that reductively dechlorinate 4-chlorophenol and transform phenol to benzoate enriched from estuarine sediment of Lake Shinji

Monochlorophenols were degraded to benzoate via phenol by the initial dechlorination and the subsequent conversion of phenol to benzoate in anaerobic sediment samples of estuarine Lake Shinji under methanogenic conditions. To characterize bacteria that dechlorinate 4-chlorophenol and transform phenol to benzoate, we analyzed the microbial community structure of the enrichment culture with each 4-chlorophenol and phenol by the limiting dilution method with polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) of 16S rRNA gene. After serial dilution of the culture, the 4-chlorophenol-dechlorinating culture consisted of two dominant bacteria, one of which was most homologous with Dehalobacter sp. In the enriched culture with phenol, minor band homologous with Cryptanaerobacter phenolicass corresponded to the transformation activity.     

Effects of dietary habits and CYP1A1 polymorphisms on blood dioxin concentrations in Japanese men

The major source of dioxin impurities in Japan in the past was agrochemical formulations; more recently, it has been exhaust from waste incinerators. To examine the environmental and genetic factors that influence blood dioxin concentration, we investigated the relationship among dioxin concentrations, dietary habits and cytochorome P450 1A1 (CYP1A1) polymorphisms (MspI type and Ile-Val type) in Japanese fishermen and farmers, including also a group of office workers as controls. The mean dioxin concentrations in the fishermen, the farmers and the controls were 161369, 79079 and 100500 pg/g fat, respectively. The elevated dioxin concentration with polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and coplanar-PCBs found in the fishermen may be due to the frequent consumption of fish; no such relationship was found both in the farmers and the controls. We found that the concentrations of congeners found as impurities in certain chemicals such as those previously used in agriculture showed no significant differences among the three groups; we consider it unlikely that the farmers would be directly exposed to dioxins from such chemicals. Thus, it is probable that the primary route of dioxin exposure in the Japanese population is through the food chain via fish consumption, regardless of occupation. No meaningful relationship between blood dioxin concentration and CYP1A1 polymorphisms was found in this study, although there was a significant difference between the concentration of total non-ortho-PCBs in genotypes A and B. Further studies on more subjects, including those of genotype C, are needed to confirm the relationship between blood dioxin concentrations and MspI polymorphisms.     

Electrodeposition of rare-earth elements from neodymium magnets using molten salt electrolysis

Rare-earth element is an important target for recycling in Japan. In our previous work, we demonstrated the selective leaching of rare-earth elements from waste neodymium magnets using chloride molten salt electrolysis. In this study, we investigated the electrodeposition of rare-earth elements using liquid metal as a cathode. The reduction potential obtained using a liquid-zinc electrode was higher than that obtained using a solid molybdenum electrode. A zinc–rare-earth alloy was formed as the electrodeposit. The total rare-earth element content of the electrodeposit was more than 99.8 mass% without zinc and other composition of electrolysis. The activity of rare-earth elements decreased upon alloy formation, suggesting that the oxidation rate of electrodeposited alloy will be decreased.     

Recovery of rare-earth elements from neodymium magnets using molten salt electrolysis

Rare-earth elements are used in neodymium magnets, and these elements are critical to Japanese industry. In this study, we focused on the electrochemical behavior of neodymium magnets for the recovery of rare-earth elements using molten salt electrolysis. The influence of the rare-earth elemental composition of the neodymium magnets on their anodic polarization behavior and oxidation mechanism was studied. The use of potentiostatic electrolysis enabled selective leaching of rare-earth elements from neodymium magnets in the potential range from ?1.8 to ?0.8 V. The oxidation potential limits the oxidation stage, enabling rare-earth elements to be leached from mixed neodymium magnets simultaneously.     

Aromatization of waste polyolefin pyrolysate over H-ZSM-5 zeolite-supported gallium oxide catalysts

H-ZSM-5 zeolite-supported gallium oxides were studied as aromatization catalysts for polyolefin pyrolysate. The catalysts were prepared by a conventional physical mixing method with a gallium content of 1.0 and 4.5 wt% and were reduced in flowing hydrogen at 585°C. To test their activity, a polyolefin sample was pyrolyzed and passed over a heated catalyst layer; the product was analyzed by gas chromatography/mass spectrometry. A continuous-flow fixed-bed reactor was used for aromatization of a model gas of polyolefin pyrolysate. For chlorine-free sources at 450°C, the catalyst with only 1.0 wt% gallium exhibited activity comparable to a gallium silicate catalyst. For chlorine-contaminated sources, the catalyst with 4.5 wt% gallium sustained catalytic activity for long periods. From the activity test results, it was found that zeolite-supported gallium catalysts prepared by the physical mixing method are suitable for converting polyolefin into aromatic hydrocarbons.     

Recycling process for yttria-stabilized tetragonal zirconia ceramics using a hydrothermal treatment

The recycling process for 3 mol% yttria-stabilized tetragonal zirconia polycrystals (3Y-TZP) sintered at 1450°–1550°C was examined by applying low-temperature degradation of zirconia ceramics under hydrothermal conditions. Hydrothermal treatment at a temperature from 200° to 240°C can lead to the spontaneous disintegration of 3Y-TZP sintered bodies into powdery particles. The hydrothermally obtained zirconia powder was found to consist of primary particles and aggregated particles. Detailed X-ray diffraction measurement revealed the formation of a cubic zirconia phase in the 3Y-TZP sintered bodies, which seemed to inhibit the disintegration of aggregated particles toward the primary particle level. The reclaimed 3Y-TZP powder was sintered again through a conventional powder processing route. The mechanical properties and microstructure of recycled 3Y-TZP sintered specimens were examined by comparison with those of the original 3Y-TZP sintered bodies. Dense recycled 3Y-TZP sintered at a higher temperature exhibited higher fracture toughness to some degree than the original 3Y-TZP.     

Patch dynamics based on Prisoner's Dilemma game: superiority of golden rule

There has been much literature on ecological model of Prisoner's Dilemma (PD) game. This game illustrates that cooperation can evolve in situations where individuals tend to look after themselves. In order to explain some behaviors of altruism in animal societies, the strategy All Cooperate (AC), often called the Golden Rule, is more appropriate than other strategies. However, very little is known about the superiority of AC. In the present article, we study patch dynamics based on non-iterated PD game, applying two different methods: island and lattice models. Each patch is assumed to be either vacant or composed of a population of AC or All Defect (AD), where AD means a selfish strategy. Both models exhibit a phase transition between a phase where both AC and AD survive, and a phase where AD is extinct. The latter phase means that AC beats AD completely. In the case of lattice model, the extinction of AD easily occurs and the abundance of AC takes a larger value, compared with the island model. Our models can be also extended to general iterated PD game; we describe the reason why AC can outperform any other strategy.     

Real-time reverse transcription PCR analysis of trichloroethylene-regulated toluene dioxygenase expression in Pseudomonas putida F1

Toluene dioxygenase (tod) is a multicomponent enzyme system in Pseudomonas putida F1. Tod can mediate the degradation of Trichloroethylene (TCE), a widespread pollutant. In this study, we try to explore the TCE-regulated tod expression by using real-time qRT-PCR. The minimal culture media were supplemented with glucose, toluene, or a mixture of glucose/toluene respectively as carbon and energy sources. The TCE was injected into each medium after a 12-hour incubation period. The TCE injection severely affected bacterial growth when cultured with toluene or toluene/glucose mixtures. The cell density dropped 61 % for bacteria growing in toluene and 36 % for bacteria in the glucose/toluene mixture after TCE injection, but the TCE treatment had little effect on bacteria supplied with glucose alone. The decrease in cell number was caused by the cytotoxicity of the TCE metabolized by tod. The results from the real-time qRT-PCR revealed that TCE was capable of inducing tod expression in a toluene-dependent manner and that the tod expression level increased 50 times in toluene and 3 times in the toluene/glucose mixture after 6 hours of TCE treatment. Furthermore, validation of the rpoD gene as a reference gene for P. putida F1 was performed in this study, providing a valuable foundation for future studies to use real-time qRT-PCR in the analysis of the P. putida F1 strain.     

SEIB–DGVM: A new Dynamic Global Vegetation Model using a spatially explicit individual-based approach

We report the development of a new spatially explicit individual-based Dynamic Global Vegetation Model (SEIB–DGVM), the first DGVM that can simulate the local interactions among individual trees within a spatially explicit virtual forest. In the model, a sample plot is placed at each grid box, and then the growth, competition, and decay of each individual tree within each plot is calculated by considering the environmental conditions for that tree as it relates to the trees that surround it. Based on these parameters only, the model simulated time lags between climate change and vegetation change. This time lags elongated when original biome was forest, because existing trees prevent newly establish trees from receiving enough sunlight and space to quickly replace the original vegetation. This time lags also elongated when horizontal heterogeneity of sunlight distribution was ignored, indicating the potential importance of horizontal heterogeneity for predicting transitional behavior of vegetation under changing climate. On a local scale, the model reproduced climate zone-specific patterns of succession, carbon dynamics, and water flux, although on a global scale, simulations were not always in agreement with observations. Because the SEIB–DGVM was formulated to the scale at which field biologists work, the measurements of relevant parameters and data comparisons are relatively straightforward, and the model should enable more robust modeling of terrestrial ecosystems.