Material flow analysis of used personal computers in Japan

Most personal computers (PCs) are discarded by consumers after the data files have been moved to a new PC. Therefore, a used PC collection scheme should be created that does not depend on the distribution route of new PCs. In Japan, manufacturers’ voluntary take-back recycling schemes were established in 2001 (for business PCs) and 2003 (for household PCs). At the same time, the export of used PCs from Japan increased, affecting the domestic PC reuse market. These regulatory and economic conditions would have changed the flow of used PCs.In this paper, we developed a method of minimizing the errors in estimating the material flow of used PCs. The method’s features include utilization of both input and output flow data and elimination of subjective estimation as much as possible. Flow rate data from existing surveys were used for estimating the flow of used PCs in Japan for fiscal years (FY) 2000, 2001, and 2004. The results show that 3.92 million and 4.88 million used PCs were discarded in FY 2000 and 2001, respectively. Approximately two-thirds of the discarded PCs were disposed of or recycled within the country, one-fourth was reused within the country, and 8% were exported. In FY 2004, 7.47 million used PCs were discarded. The ratio of domestic disposal and recycling decreased to 37% in FY 2004, whereas the domestic reuse and export ratios increased to 37% and 26%, respectively. Flows from businesses to retailers in FY 2004 increased dramatically, which led to increased domestic reuse. An increase in the flow of used PCs from lease and rental companies to secondhand shops has led to increased exports. Results of interviews with members of PC reuse companies were and trade statistics were used to verify the results of our estimation of domestic reuse and export of used PCs.     

Hydrolysis of <Emphasis Type="Italic">Sasa senanensis</Emphasis> culm with dilute sulfuric acid for production of a fermentable substrate

To prepare a substrate for microbial conversion of xylose into xylitol, the culm of Sasa senanensis was hydrolyzed with dilute sulfuric acid. When the reaction temperature was fixed at 121°C, an optimum yield of xylose was obtained by treatment with 2% sulfuric acid for 1 h. An increase in the sulfuric acid concentration or a prolonged reaction time resulted in a decrease in the xylose yield. A fermentable substrate with a relatively high xylose concentration (36.7 g l⁻¹) was obtained by hydrolysis with 2% sulfuric acid with a liquid-to-solid ratio of 5 g g⁻¹. During hydrolysis at elevated temperatures, certain undesired byproducts were also generated, such as degradation products of solubilized sugars and lignin, which are potential inhibitors of microbial metabolism. These compounds were, however, successfully removed from the hydrolysate by treatment with activated char.     

Local Circulation with Aeolian Dust on the Slopes and Foot Areas of the Tianshan and Kunlun Mountains around the Taklimakan Desert, China

Four automatic weather stations (AWS) were installed on the slopes and foot areas of the Tianshan and Kunlun Mountains along a longitude of 80 degrees east: (1) Taglak 2400 m a.s.l., (2) Aksu 1000 m, (3) Kartash 2800 m, and (4) Qira 1700 m. These two slopes face the Taklimakan Desert. Tagliak lies on the southern slope of Tianshan, and Kartash on the northern slope of Kunlun. The meteorological characteristics of the mountainous regions were investigated using surface data obtained during an intensive observation period (IOP) in spring 2002. It was found that visibility on the slopes decreases in the daytime, and there is no relationship between visibility and wind speed in the mountainous areas. Two snow layers containing dust particles were observed in the snow cover in Taglak during the IOP in spring 2003. These results suggest that a warm air parcel containing aeolian dust climbs over the slopes of the mountainous areas, and dust particles in the mountainous areas are transported from the foot areas.     

Correlation between flash points and vapor pressures of organic compounds

Correlations between flash points and vapor pressures at 25 °C for pure organic compounds were investigated. It was found that classification of organic compounds according to their chemical-structural characteristics (e.g., functional groups) was necessary for the correlation study. Under this classification, linearity seems to be the most appropriate correlation to explain the relationship between the inverse of flash points (°K) and the logarithm of vapor pressures (mm Hg) at 25°C for pure organic compounds. A test study to evaluate the validity of a regression line as an estimation of an unknown flash point from a known vapor pressure was carried out with a data set containing 31 alkanes and aromatics; 55% of the flash points were predicted within ±5°Cand89% were within ±10°C. Within limits of ± 5 to 10°C the procedure is useful but should be improved.     

Dechlorination of polychlorinated organic compounds by electrochemical reduction with naphthalene radical anion as mediator

Electrochemical reduction with electrochemically generated naphthalene radical anion in N,N-dimethylformamide was applied to the dechlorination of five representative POPs, namely HCB, lindane, DDT, PCP and aldrin. Rapid and complete dechlorination was possible for lindane and DDT to give nearly quantitative yields of benzene and 1,1-diphenylethane, respectively. HCB was reduced through complex reaction pathways to yield unknown products. Dechlorination of PCP and aldrin beyond dichlorinated compounds was difficult because of their very negative reduction potential. The reaction pathways for each dechlorination were proposed with the identification of intermediates.     

Endocrine disrupter nonylphenol and bisphenol A contamination in Okinawa and Ishigaki Islands, Japan--within coral reefs and adjacent river mouths

Certain chemicals possess the potential to modulate endocrine systems, and thereby interfere with reproduction and developmental processes in the wild. We analyzed endocrine disrupters nonylphenol (NP) and bisphenol A (BPA) levels at various sites in Okinawa and Ishigaki Islands, Japan. River-water samples showed undetectable to low concentrations of NP and BPA at most of the sites investigated. However, an appreciable amount of BPA was detected in sediments at one coral reef site. In addition, significant numbers of river sediment samples showed appreciable amounts of NP and BPA. Most of the sampling sites for this study are located within a distance of 1 km from the coral reefs, which are under influence of river-waters to a variable extent. Therefore, influence of endocrine disrupters may have already begun on adjacent coral reefs. Both endocrine disrupters were positively correlated with human population densities, but not with the contents of red soil generated by farm land reformation. Therefore, it is concluded that NP and BPA pollution is a consequence of human waste discharge, both domestic and industrial, and not by agricultural activities.     

Seasonality,lunar periodicity of settlement and microhabitat association of juvenile humpback red snapper <Emphasis Type="Italic">Lutjanus gibbus</Emphasis> (Lutjanidae) in an Okinawan coral reef

Snappers (Lutjanidae) are one of the important fisheries resources in tropical and subtropical waters. However, there have been few studies clarifying the ecology of newly settled juvenile snappers. The aims of the present study were to clarify the seasonality and lunar periodicity of the larval settlement, and the microhabitat association of newly settled juveniles for Lutjanus gibbus in an Okinawan coral reef. Fifteen coral patches were chosen and underwater visual surveys were conducted during a 2-year period. The larval settlement of the species mainly occurred between May and October during the 2-year survey period. In terms of lunar periodicity of the settlement, the newly settled juveniles were mainly found between the last quarter moon and new moon during the main settlement season. Back calculations of settlement dates based on otolith microstructure showed that most juveniles settled during the last quarter moon and new moon. Stepwise multiple regression analyses revealed that the newly settled juveniles were mainly found on coral patches with a large number of holes on the top of the coral patch and this tendency was mainly consistent during the study period. The volume of holes at the base of coral patches had also a positive effect on the abundance of newly settled juveniles in some cases. The results of the present study suggest that larval settlement has a strong seasonal and lunar periodicity, and newly settled juveniles select coral patches with available refuge spaces.     

An overlooked side effect of nest-scattering behavior to decrease predation risk (Acari: Tetranychidae,Stigmaeidae)

The number of nests containing egg masses a female makes over her lifetime and the pattern of scattering nests vary among species in a genus of nest-weaving spider mites (Stigmaeopsis). We hypothesized that the scattered nests of small nest builders have a previously overlooked indirect effect in that the void nests created after predation take on a new role as hindering devices that effectively decrease predator searching efficiency. First, we demonstrated that the experimental design used in this study is a good reflection of the nest distribution pattern of Stigmaeopsis takahashii (an intermediate-sized nest builder) in the field. Using this species as a model, we tested how different nest-scattering patterns affect the predator to examine how scattering may indirectly provide an anti-predation strategy by increasing a predators searching time. Next, we observed how artificially arranged void nests disturb predatory behavior in both starved and fully fed predator females and showed that void nests have a strong hindering effect on predators. Thus, we concluded that the nesting behavior of this mite species not only has anti-predator effects but must also have a stabilizing effect on predator–prey interaction systems at the population level.