Improved method for the formation of recycled resins from depolymerized products of waste fiber-reinforced plastics: simple and effective purification of recovered monomers by washing with water

The synthesis of recycled plastics from recovered monomeric materials obtained from the depolymerization reaction of fiber-reinforced plastics (FRP) was examined. The depolymerization reaction of FRP in the presence of N,N-dimethylaminopyridine (DMAP) smoothly yielded the corresponding monomers, which mainly consisted of dimethyl phthalates. The polymerization reaction with this monomer failed to form the corresponding unsaturated polyesters due to contamination by N-methyl-4-pyridone, a decomposition product of DMAP. An efficient purification of the recovered monomer was achieved by washing with water, and the purified monomer successfully yielded the corresponding polymers. A hardness test revealed that the polymers were as hard as the polyester made from virgin materials. The present modification provides a practical method for the preparation of recycled plastics from depolymerized plastics.     

Toward knowledge structuring of sustainability science based on ontology engineering

In sustainability science (SS), it is difficult to identify what needs to be solved, and it is also not clear how to solve the problems that are identified. There has been no consensus on the underlying question of “What is structuring knowledge in SS?” This paper focuses on knowledge structuring accompanied by supporting of thinking. It addresses the key challenges associated with knowledge structuring in SS, identifies the requirements for the structuring of knowledge, proposes a reference model, and develops an ontology-based mapping tool as a solution to one layer of the reference model. First, we identify the important requirements for SS knowledge structuring. Second, we develop a reference model composed of five layers based on three of the requirements. Third, we develop an ontology-based mapping tool at Layer 2 of the reference model for meeting the two major challenges for SS, namely, identifying what problems should be addressed in SS itself and proposing solutions for those problems. The tool is designed to store and retrieve information regarding SS, to provide access to a prototype ontology for SS, and to create multiple maps of conceptual chains depending on a user’s interests and perspectives. Finally, we assess whether the developed tool successfully realizes the targeted part of the reference model for SS by examining the tool’s conformity to the reference model, as well as its usability, effectiveness, and constraints. Although several issues were identified in the prototype ontology and the mapping tool, the study concluded that the mapping tool is useful enough to facilitate the function of Layer 2. In particular, the mapping tool can support thinking about SS from the viewpoint of: (a) finding new potentials and risks of technological countermeasures studied in SS; (b) helping users to get a more comprehensive picture of problems and their potential solutions; and (c) providing an effective opportunity to come up with new ideas that might not be thought of without such a tool.     

Characterization of semi-volatile organic compounds emitted during heating of nitrogen-containing plastics at low temperature

Because of recent volume increases, appropriate management of plastic recycling, which generates various organic compounds, is required to ensure the chemical safety of the processes. The processing temperature and resin type are the important factors determining both the efficiency of the processes and the emission of chemicals. Therefore, we studied the thermal degradation of various plastics at various temperatures from 70 to 300 °C under oxygen-present conditions to identify the semi-volatile organic compounds (SVOCs) emitted and to understand their thermal behaviors. The plastics examined were nitrogen-containing resins, such as polyamide 6, polyurethane, melamine formaldehyde, urea formaldehyde and acrylonitrile-butadiene-styrene. Major commodity plastics were also investigated for comparison. In total, more than 500 SVOCs were detected as emissions from plastics. While various nitrogen-containing SVOCs were detected from nitrogen-containing resins, the major commodity plastics released only these, which possibly were included as additives. These results indicate that the nitrogen atoms in the SVOCs emitted originated from the resins and additives, and not from ambient air at low temperature. As a result of the detection of raw materials, degradation chemicals and by-products of the polymers in the emissions, we found that the variation in chemical species is dependent on the resins. Additives were also emitted from all the resins, meaning that these chemicals were also released to the environment at the temperature examined. In most cases, the numbers and concentrations of SVOCs increased with increasing heating temperature. The variation of thermal behaviors of SVOCs was related to the origins and chemical species of SVOCs.     

Age-dependent accumulation of heavy metals in a pod of killer whales (Orcinus orca) stranded in the northern area of Japan

Mercury (Hg), cadmium (Cd), iron (Fe) manganese (Mn), zinc (Zn) and copper (Cu) concentrations in the liver, kidney and muscle of nine killer whales (including three calves) that stranded together in the northern area of Japan were determined. The Hg and Cd concentrations were found at trace levels in the calf organs, and increased with age. The Fe concentration in the muscle was significantly lower in the calves than in the mature whales and also increased with age. In contrast, Mn and Cu concentrations in the muscle were significantly higher in the calves than in the mature whales, and changes in the Zn concentration relative to age were unclear. These results suggest minimal mother-to-calf transfer of the toxic metals Hg and Cd and accumulation of these metals in the organs with age, while the essential metals Mn and Cu were found at higher concentrations in the muscle of calves than in mature whales.     

Can’t See the Forest for the Rice: Factors Influencing Spatial Variations in the Density of Trees in Paddy Fields in Northeast Thailand

The widespread presence of trees in paddy fields is a unique feature of Northeast Thailand’s agricultural landscape. A survey of spatial variability in the density of trees in paddy fields in the Northeast Region was conducted utilizing high resolution satellite images and found that the mean density in the whole region was 12.1 trees/ha (varying from a high of 44.6 trees/ha to a low of 0.8 trees/ha). In general, tree densities are higher in the southeastern part of the region and much lower in the northern central part. Tree density was influenced by multiple factors including: (1) the history of land development, with more recently developed paddy fields having higher densities, (2) topography, with fields located at higher topographical positions having a higher mean density of trees, (3) access to natural forest resources, with fields in areas located close to natural forests having higher densities, (4) amount of annual rainfall, with fields in areas with higher average annual rainfall having higher tree densities, and (5) landholding size, with fields in areas with larger-sized landholdings having more trees. However, there is a considerable extent of co-variation among these factors. Although trees remain an important element of the paddy field landscape in the Northeast, it appears that their density has been declining in recent years. If this trend continues, then the vast “invisible forest” represented by trees in paddy fields may truly disappear, with negative consequences for the villagers’ livelihoods, biodiversity conservation, and carbon sequestration in the rural ecosystem.     

Viral Interference as a Factor of False-Negative in the Infectious Adenovirus Detection Using Integrated Cell Culture-PCR with a BGM Cell Line

Food and Environmental Virology - This study investigated the influence of viral interference on the detection of enteric viruses using the integrated cell culture (ICC)-PCR with a BGM cell line....     

Phylogeny and biogeography of Sicydiinae (Teleostei: Gobiidae) inferred from mitochondrial and nuclear genes

In the Indo-Pacific area, the Caribbean region and West Africa, insular systems are colonised by particular Gobiids of the Sicydiinae subfamily. These species spawn in freshwater, the free embryos drift downstream to the sea where they undergo a planktonic phase, before returning to rivers to grow and reproduce; an amphidromous lifestyle. These gobies are the biggest contributors to the diversity of fish communities in insular systems and have the highest levels of endemism, yet their phylogeny has not been explored before with molecular data. To understand the phylogeny and the biogeography of this subfamily, sequences from the mitochondrial 16S rDNA and cytochrome oxidase I and from the nuclear rhodopsin gene were obtained for 50 Sicydiinae specimens of seven genera. Our results support the monophyly of the subfamily and of all the genera except Sicyopus, which is polyphyletic. Five major clades were identified within this subfamily. One clade clusters Sicyopterus and Sicydium as sister genera, one contains the genus Stiphodon split into two different groups, two other clades include only Sicyopus (Smilosicyopus) and Cotylopus, respectively, and the last clade groups Akihito, Lentipes and Sicyopus (Sicyopus). As a result, the subgenus Smilosicyopus is elevated herein as a genus. A molecular dating approach helps the interpretation of these phylogenetic results in terms of amphidromy and biogeographical events that have allowed the Sicydiinae to colonise the Indo-Pacific, West African and Caribbean islands.     

Morphological and habitat divergence in the intertidal limpet Patelloida pygmaea

In the intertidal limpet Patelloida pygmaea, two distinctive morphs, the forms pygmaea and conulus, have been recorded. The former possesses a flat elongated shell, and the latter has an extremely high round shell. It has been observed in the field that pygmaea is found on oyster shells Crassostrea gigas. The form conulus uses an unusual substrate for attachment. It is found on the living shells of the intertidal gastropod Batillaria cumingi. Although conulus is normally found only on shells of Batillaria, it can also be found on oyster shells when pygmaea and Batillaria shells are not present in nature. An electrophoretic analysis of allozymes showed that these two forms are reproductively isolated from each other and coexist without gene exchange on the same mudflat. Laboratory experiments showed that pygmaea prefers oyster shells and conulus prefers Batillaria shells as substrates for attachment when both oyster and Batillaria shells are present. The form pygmaea did not attach to Batillaria shells, even when only Batillaria shells were available. However, conulus also attached to oyster shells when Batillaria shells were not available. The proportion of individuals of conulus that attached to oyster shells decreased significantly when pygmaea was attaching to the oyster shells. These results suggest that pygmaea is ecologically more specialized to living on oyster shells than conulus.