Trajectory and factors of radiation risk perception of students aged 10-12 years at the time of the Fukushima Daiichi Nuclear Power Station accident.

Various studies have investigated radiation risk perceptions after the accident at the Fukushima Daiichi Nuclear Power Station. However, student surveys are limited. This study aimed to investigate the perception of radiation risk among students aged 18-20 years who were in the 5th and 6th grades of elementary school at the time of the accident. We surveyed students in the Fukushima Prefecture and outside the prefecture. Out of all the data, 59% of the respondents were living in the Fukushima Prefecture at the time of the accident and 41% outside the prefecture. Trajectory analysis showed that changes in anxiety levels over time since 2011 could be divided into five classes: (a) the anxiety was the highest, and this tendency persisted. (b) High at the beginning, but decreased more quickly than class 1. (c) High at the beginning, but it diminished quickly. (d) Not high, but did not diminish easily in later years. (e) Low from the beginning, and persisted. Multinomial logistic analysis showed that among students living outside the prefecture at the time of the accident, a significantly higher proportion was in groups 4 and 5 than in group 2. A significant proportion of boys were present in groups 3, 4 and 5. A significant proportion of students whose current educational institutions were inside the prefecture were present in group 3. The level of anxiety was associated with the academic course, but not with subjective knowledge of radiation. In contrast, in the qualitative analysis of the free text, 31% considered 'knowledge about radiation' as the reason for the reduction in anxiety level. At the time of the investigation, most young people were not anxious about radiation. However, approximately 20% still had strong anxiety. We established that continuous risk communication is necessary. Furthermore, that stabilization and support related to life in general is important.

Differences in the removal mechanisms of Undaria pinnatifida and Phragmites australis as biomaterials for lead removal.

This study offers the opportunity to utilize Undaria pinnatifida and Phragmites australis to remove lead from water in permeable reactive barrier (PRB) technology. Its efficacy was tested using batch experiments and PRB column systems. From the batch experiment results, a higher adsorption capacity was observed for Undaria pinnatifida. Nevertheless, Phragmites australis in the column system efficiently removed lead and the breakthrough occurred at the same time for both biomaterials. To dissipate this difference, a sequential extraction for metal speciation analysis was used for both columns. The results have shown that each biomaterial has a dominant mechanism. Phragmites australis removed lead by physical adsorption, whereas Undaria pinnatifida showed a higher tendency to bind lead due to organic matter, primary and secondary minerals.

Lead removal efficiency using biosorbents as alternative materials for permeable reactive barriers.

As alternative materials for heavy metal removal, this study investigated biosorbents to determine their suitability for permeable reactive barriers. The lead removal efficiencies of brown seaweed (Undaria pinnatifida) and reed (Phragmites australis) were determined under different conditions (batch and column system). The experimental results for these biomaterials fitted the Langmuir isotherm with high correlation values. It was verified that the influence of temperature on affinity was higher than that on adsorption capacity. While the lead removal efficiency of U. pinnatifida was higher than of P. australis in the batch experiments, lead removal efficiency decreased for both materials at approximately the same time in the column experiments. This indicates that the dominance of the chemical and physical adsorption mechanisms could result in differences in these systems.

Effects of genotypic diversity of Phragmites australis on primary productivity and water quality in an experimental wetland.

An increasing number of studies have shown that genetic diversity within plant species can influence important ecological processes. Here, we report a two-year wetland mesocosm experiment in which genotypic richness of Phragmites australis was manipulated to examine its effects on primary productivity and nitrogen removal from water. We used six genotypes of P. australis, and compared primary productivity and nitrogen concentration in the outflow water of the mesocosms between monocultures and polycultures of all six genotypes. We also quantified the abundance of denitrifying bacteria, as denitrification is a primary mechanism of nitrogen removal in addition to the biotic uptake by P. australis. Plant productivity was significantly greater in genotypic polycultures compared to what was expected based on monocultures. This richness effect on productivity was driven by both complementary and competitive interactions among genotypes. In addition, nitrogen removal rates of mesocosms were generally greater in genotypic polycultures compared to those expected based on monocultures. This effect, particularly pronounced in autumn, may largely be attributable to the enhanced uptake of nitrogen by P. australis, as the abundance of nitrite reducers did not increase with plant genotypic diversity. Although our effect sizes were relatively small compared to previous experiments, our study emphasizes the effect of genotypic interactions in regulating multiple ecological processes.

Development and application of a simulation model for the thermophilic oxic process for treating swine waste.

The thermophilic oxic process (TOP) is a composting process that enables simultaneous complete decomposition and evaporation of organic waste under high temperature conditions supported by well-balanced calorific value control. To develop the simulation model for TOP, three-dimensional relationships among decomposition rate constant, temperature (20-70 °C) and moisture content (30-70%) were determined for swine waste and cooking oil based on the oxygen consumption rate during a thermophilic oxic decomposition reaction. The decomposition rate of swine waste and cooking oil under various moisture contents was described by the Arrhenius equation. The optimal temperature and moisture content were 60 °C and 60% for swine waste and 60 °C and 50% for cooking oil, respectively. The simulation model for TOP was constructed on the basis of the carbon, heat, and moisture balance. The validation of the simulation model was examined by comparing the measured temperature in the TOP reactor to that estimated by the simulation. The simulation model was proven by comparing experimental and calculated values. The relationship between the injection calorific value and the process mechanism of TOP was interpreted by the simulation model. On the basis of their relationship during TOP, the appropriate process conditions were discussed.

Estrogen removal from treated municipal effluent in small-scale constructed wetland with different depth.

The presence of estrone (E1), 17 beta-estradiol (E2) and 17 alpha-ethynylestradiol (EE2) in sewage treatment work (STW) effluent pose a potential risk to aquatic ecosystem. The objectives of this study were to evaluate the effectiveness of vertical-flow wetland as polishing step of conventional wastewater treatment in the removal of estrogens and to examine the effect of sand depth. The highest removal efficiency of 67.8+/-28.0%, 84.0+/-15.4% and 75.3+/-17.6% for E1, E2 and EE2, respectively, was achieved by the shallowest wetland among three constructed wetlands with different filter layer depth (i.e. 7.5, 30 and 60 cm). Together with the result that the performance of wetlands when operating in unsaturated condition was superior to that when operating in water-saturated condition, it is suggested that maintaining sufficient aerobic circumstance in constructed wetlands was important for estrogens removal. Core sampling indicated that the highest efficiency achieved in extremely shallow wetland might be due partly to the highest root density, besides the superior condition for penetration of oxygen. The adsorbed estrogens in sand accounted for less than 12% of the removed estrogens irrespective of the depth, indicating biotic processes play a major role in the estrogens removal.

Flexible host frameworks with diverse cavities in inclusion crystals of bile acids and their derivatives.

We have systematically investigated structures and properties of inclusion crystals of bile acids and their derivatives. These steroidal compounds form diverse host frameworks having zero-, one- and two-dimensional cavities, causing various inclusion behaviors towards many organic compounds. The diverse host frameworks exhibit the following guest-dependent flexibility. First, the frameworks mainly depend on the included guests in size and shape. The size-dependence is quantitatively estimated by the parameter PCcavity, which is the volume ratio of a guest molecule to a host cavity. The resulting values of PCcavity lie in the range of 42-76%. Second, each of the host frameworks has its own range of the values. Some guests can employ two different frameworks with the boundary values, explaining formation of polymorphic crystals. Third, the host frameworks are selected by host-guest interactions through weak hydrogen bonds, such as NH/pi and CH/O. The weak hydrogen bonds play an important role for various selective inclusion processes. Fourth, the host frameworks are dynamically exchangeable, resulting in intercalation and polymerization in the cavities. These static and dynamic structures of the frameworks demonstrate great potential of crystalline organic inclusion compounds as functional materials.

Effects of bacterial activity on estrogen removal in nitrifying activated sludge.

The effects of bacterial activity on the degradation of estrone (E1), estradiol (E2), estriol (E3) and ethinylestradiol (EE2) in nitrifying activated sludge (NAS) were studied with different substrates and organic loading rates (OLRs) and low temperature conditions. Heterotroph was shown to have utilized glucose prior to E1 for metabolism. The co-metabolism of ammonia oxidizing bacteria (AOB) dominated the degradation of E1, E2 and EE2 in NAS. The higher the organic loading, the higher the rate of organic matter transformation, with less ammonia oxidation and less degradation of E1, E2 and EE2. The degradation of E3 in NAS was shown to be largely due to heterotroph metabolism. On the basis of the difference of apparent activity between heterotroph and AOB at 4 degrees C, the process of estrogen degradation via the co-metabolism of AOB was able to be identified.

A thermodynamic analysis on adsorption of estrogens in activated sludge process.

The adsorption behaviors of estrone (E1), 17beta-estradiol (E2), estriol (E3), 17 alpha-ethinylestradiol (EE2), and equol were studied with a deactivated sludge subjected to heat treatment at 80 degrees C for 30 min. The heat-treatment hardly changed the adsorption features of activated sludge (AS). The adsorption equilibrium of all estrogens was approached within 10 min at 20 degrees C, and a high removal of estrogens was achieved simultaneously. The equilibrium data were well fitted by a Freundlich isotherm. The adsorption behaviors of E1, E2, E3 and EE2 in the AS system were independent of their Kow values. Thermodynamic analysis revealed that the adsorption behaviors of E1, E2, E3 and EE2 could be considered as an exothermic, physical and reversible process, resulting in their higher adsorption capacities at lower temperature. Regarding equol, its adsorption was an endothermic, chemical and irreversible process.

Phragmites australis: a novel biosorbent for the removal of heavy metals from aqueous solution.

Reed (Phragmites australis), a commonly used macrophyte in the wetlands constructed for water purification, was investigated as a new biosorbent for the removal of Cu(2+), Cd(2+), Ni(2+), Pb(2+) and Zn(2+) from aqueous solution. The metal adsorption capacity of reed biomass was improved significantly by water-wash, base- and acid-treatment. The maximum sorption of NaOH-pretreated reed biomass was observed near neutral pH for Cu(2+), Cd(2+), Ni(2+) and Zn(2+), while that for Pb(2+) was from an acidic range of pH 4.0 or higher. The maximum metal adsorption capacity on a molar basis assumed by Langmuir model was in the order of Cu(2+)>Ni(2+)>Cd(2+)>Zn(2+)>Pb(2+). Reed biosorbent showed a very high adsorption affinity value, which helps predict its high ability to adsorb heavy metals at low concentration. Desorption of heavy metals and regeneration of the biosorbent was attained simultaneously by acid elution. Even after three cycles of adsorption-elution, the adsorption capacity was regained completely and the desorption efficiency of metal was maintained at around 90%.

Construction of superhydrophobic surfaces by fibrous aggregation of perfluoroalkyl chain-containing organogelators.

Superhydrophobic surfaces, characterized by water contact angles greater than 150 degrees, can be produced by means of intermediate organogels, which were formed by perfluoroalkyl chain-containing organogelators with volatile organic solvents.

Organic intercalation material: reversible change in interlayer distances by guest release and insertion in sandwich-type inclusion crystals of cholic acid.

Cholic acid (CA) forms inclusion crystals that have a sandwich-type lamellar structure constructed by the alternative stacking of host bilayers and guest layers. Five disubstituted benzenes, o-toluidine, m-fluoroaniline, o-chlorotoluene, o-bromotoluene, and indene, are accommodated in the two-dimensional void space between the host bilayers at 1:2 host-guest stoichiometries. Thermal gravimetric analysis of the inclusion crystals revealed that all the guest molecules, except o-toluidine, are released in two separate steps, indicating the formation of intermediate crystals after the first guest release. Adequate heat treatment of the four inclusion crystals induces release of half or three quarters of the guest molecules. X-ray diffraction patterns of the intermediate crystals revealed that the crystals have a bilayer structure the same as those of the common CA inclusion crystals. They have one-dimensional cavities, in which the guest molecules are included at a 1:1 or 2:1 host-guest stoichiometry. These facts indicate that the host bilayers move 1.6-4.5 A perpendicular to the layer direction by desorption of the guest molecules. Furthermore, a reverse structural change is also achieved by absorption of the guest molecules to regenerate the starting sandwich-type inclusion crystals. This reversible change in the host bilayer by the guest sorption and desorption is a novel example of organic intercalation materials.

Dependence of selective enclathration on types of cholic acid crystals.

Competitive recrystallizations of cholic acid (CA) from 1:1 binary mixtures of seven mono-substituted benzenes are demonstrated. The order of preference for guests to be incorporated into the cholic acid crystals are as follows: benzene, toluene > n-amylbenzene, n-hexylbenzene > ethylbenzene, n-propylbenzene, n-butylbenzene. These seven compounds afford bilayer type inclusion crystals that are classified into four types based on the host frameworks and host-guest stoichiometries. The order of selective enclathration corresponds to the four types as follows: 1:1 alpha G > 2:1 alpha G > 1:1 beta T or 2:1 alpha T. The preference for the alpha G type was also confirmed by investigating the host frameworks of the crystals obtained from binary mixtures. The dependence of the selectivity on the different types of CA crystals can be understood in terms of the fit of the guest molecule in the host cavity.

Flavobacterium limicola sp. nov., a psychrophilic, organic-polymer-degrading bacterium isolated from freshwater sediments.

Three novel strains of cold-adapted bacteria, ST-82T, ST-10 and ST-92, were isolated from freshwater sediments. These three isolates were very similar to each other in phenotypic and chemotaxonomic traits, as well as in 16S rDNA sequence. The strains were Gram-negative, elongated filament-like rods that formed bright yellow colonies. They showed neither flexirubin pigments nor gliding motility. The strains were able to hydrolyse casein, gelatin, starch, agar, aesculin, urea, uric acid and tyrosine. They also lysed cells of Escherichia coil and Pseudomonas putida. The temperature range for growth was 0-25 degrees C, with optimum growth occurring at 15-20 degrees C. For all isolates, protease secretion increased as temperature decreased. Sodium chloride inhibited their growth, although the strains tolerated up to 1.5% (w/v) NaCl. Menaquinone-6 was the major respiratory quinone. The major cellular fatty acids were C15 : 0, iso-C15 : 0, anteiso-C15 : 0, C15:1, iso-C15:1, C16 : 1omega7cis, iso-C16 : 1, iso-C17 : 1, iso-C15 : 3-OH and iso-C16 : 0 3-OH. The DNA G + C content was 34.0-34.8 mol%. Phylogenetic analysis based on 16S rDNA sequences suggested that the strains belonged to the genus Flavobacterium and were closely related to Flavobacterium xanthum and Flavobacterium frigidarium, with sequence similarities of 96.9 and 96.3%, respectively. In physiological and biochemical analyses, the isolates were differentiated from all known members of the genus Flavobacterium. The name Flavobacterium limicola is proposed for these novel strains, and the type strain is ST-82T (=JCM 11473T =DSM 15094T).

A novel cyanobacteriolytic bacterium, Bacillus cereus, isolated from a Eutrophic Lake.

Isolation and screening of cyanobacteriolytic bacteria were carried out. Fifteen strains of cyano-bacteriolytic bacteria were isolated by the double layer method using the cyanobacterium, Microcystis, as a sole nutrient. The isolate, N-14, showing the highest cyanobacteriolytic activity was identified as Bacillus cereus based on the 16S rRNA sequence. Components among the extracellular products in the culture supernatant of B. cereus were responsible for the cyanobacteriolytic activity. Lytic assay tests of culture supernatants indicated that the major substances for lytic activity could be non-proteinaceous, and hydrophilic, heat stable, and with a molecular weight of less than 2 kDa. The highest lytic activity was obtained under alkaline conditions, indicating an advantage for the practical application of water bloom control in eutrophic lakes where the pH is usually in the alkaline region. The lytic substance of B. cereus N-14 were compared with enterotoxins and an emetic toxin produced by a pathogenic strain of B. cereus, and also with a known algicide produced by Bacillus brevis, gramicidin. From these results, the lytic substance seemed to be a novel algicide.

On-site nitrate removal of groundwater by an immobilized psychrophilic denitrifier using soluble starch as a carbon source.

On-site denitrification of nitrate-contaminated groundwater was conducted at 15 degrees C using a facultative psychrophilic denitrifier (strain 47) immobilized on macro-porous cellulose carriers and utilizing soluble starch as a non-toxic carbon source. A C/N ratio of 2.5 to 3.0 and a P/N ratio of 0.05 to 0.10 were found to allow complete denitrification of the groundwater used in this study. Under these conditions, the long-term performance of the system (4 months) was examined by decreasing the HRT (hydraulic retention time) from 4 h to 0.25 h. The process was stable and 95 to 100% of the influent nitrogen (NO3-N ranging from 13.0 to 16.5 mgl(-1) was removed until an HRT of 0.75 h was reached. The maximum NO3-N removal rate was 0.46 kg-Nm(-3)d(-1) at an HRT of 0.75 h. Nitrogen removal efficiency of 99.5% at an HRT of 1 h was obtained with a C/N ratio 2.58, corresponding to 4.3 g of soluble starch per 1 g of NO3-N.

Utilization of dehydrated sewage sludge as an alternative nutrient to stimulate lipid waste degradation by the thermophilic oxic process.

Dehydrated and dried powdered sewage sludge (SW) was examined for use as an alternative to yeast extract (YE) to promote the degradation of lipid materials by a thermophilic oxic process (TOP). Its stimulatory effect on lipid degradation was found to be superior to that of YE. When 1.5 g of SW was added in combination with urea and 60 ml of a trace-element solution, the degradation efficiency was 82.9% for a 120-h treatment of 15 g of salad oil while that attained with YE was 68.3%. Although the degradation efficiency attained for animal fat, lard, was 77.8% which was lower than for vegetable oil, salad oil, it was still comparable to that obtained with YE, 76.9%. The applicability of SW to lipid degradation was confirmed in tests on three kinds of highly concentrated lipid wastes. With a nutrient supplement consisting of SW, a constant degradation efficiency of around 75% in 120-h treatment was attained for all lipid wastes despite their different features. The results of an elemental analysis suggested that the effectiveness of SW as a nutrient to stimulate thermophilic microbial activity in TOP was attributable to both a sufficient quantity and variety of amino acids and mineral components.