Effect of void structure of photocatalyst paper on VOC decomposition

TiO₂ powder-containing paper composites, called TiO₂ paper, were prepared by a papermaking technique, and their photocatalytic efficiency was investigated. The TiO₂ paper has a porous structure originating from the layered pulp fiber network, with TiO₂ powders scattered on the fiber matrix. Under UV irradiation, the TiO₂ paper decomposed gaseous acetaldehyde more effectively than powdery TiO₂ and a pulp/TiO₂ mixture not in paper form. Scanning electron microscopy and mercury intrusion analysis revealed that the TiO₂ paper had characteristic unique voids ca. 10 μm in diameter, which might have contributed to the improved photocatalytic performance. TiO₂ paper composites having different void structures were prepared by using beaten pulp fibers with different degrees of freeness and/or ceramic fibers. The photodecomposition efficiency was affected by the void structure of the photocatalyst paper, and the initial degradation rate of acetaldehyde increased with an increase in the total pore volume of TiO₂ paper. The paper voids presumably provided suitable conditions for TiO₂ catalysis, resulting in higher photocatalytic performance by TiO₂ paper than by TiO₂ powder and a pulp/TiO₂ mixture not in paper form.     

Seasonal variation in the atmospheric deposition of inorganic constituents and canopy interactions in a Japanese cedar forest

The seasonal changes in throughfall (TF) and stemflow (SF) chemistry and the canopy interactions of K+ and N compounds were studied in a Japanese cedar forest near the Sea of Japan. The fluxes of most ions, including non-sea-salt SO4(2-), from TF, SF, and rainfall showed distinct seasonal trends, increasing from autumn to winter, owing to the seasonal west wind, while the fluxes of NH4+ and K+ ions from TF+SF might have a large effect of canopy interactions. The contact angle (CA) of water droplets on leaves decreased with leaf aging, suggesting that surface wettability increases with leaf age. The K+ concentration in TF was negatively correlated with the CA of 1-year-old leaves, while the NH4+ concentration was positively correlated with the CA. The net fluxes of NH4+ and NO3(-) from TF were positively correlated with the CA. The increase in wettability may accelerate leaching of K+ or uptake of NH4+.     

Volatilization behavior of lead from molten slag under conditions simulating municipal solid waste melting

To reutilize molten slag derived from an ash melting process, the lead volatilization mechanism under reducing conditions was investigated. Reducing conditions were established by introducing a CO-CO₂-N₂ gas mixture to the reactor or by adding graphite to the molten slag prior to the experiments. As samples, two types of simulated molten slag composed of CaO-SiO₂-Al₂O₃ mixed with PbO were used and the lead volatilization behavior was studied at 1773 K. It was found that the lead volatilization rate increased on increasing the amount of reducing agent for both graphite and the CO-CO₂ gas mixture. For the CO-CO₂ reducing gas mixture, this increase was mainly attributed to PbO conversion to Pb. For the addition of graphite, the increase in lead volatilization ratio was considered to partially result from PbO conversion to Pb and partially from a reaction of graphite with SiO₂ yielding volatile SiO. The volatile SiO gas was then emitted from the furnace, which brought about a reduction in the SiO₂ content of the slag. As a result, the slag viscosity decreased, which led to an enhancement of the lead volatilization ratio.     

Condition-dependent sex allocation by clones of a galling aphid

Local mate competition (LMC) has been postulated to be the primary factor of female-biased sex allocation. In animals such as aphids that exhibit seasonal alternations of clonal and sexual reproduction, there is a high possibility of intra-clonal mating and LMC. This possibility is more plausible for more fecund clones, but outbreeding is predicted for less fecund clones. We hypothesize that clones that are more fecund will gain higher fitness returns by reducing investment in males because of more intense LMC among clonal males. We tested this hypothesis by elucidating the clonal sex allocation patterns of the galling aphid Kaltenbachiella japonica, in which inbreeding and LMC appear to be common. Winged mothers that emerge from a gall, belonging to the same clone, produced males and sexual females asexually on a branch, without dispersing to other trees. The heavier the gall, the more winged mothers were produced from the gall. Individual mothers produced a constant number of males and a variable number of females. The clonal sex allocation to males was 39.8?%, on average, and decreased with increasing gall weight. This result showed that clones that were more fecund exhibited more female-biased sex allocation and thus supported our hypothesis. Furthermore, our results corroborated Stubblefield and Seger’s hypothesis for sex allocation in patch structure rather than Yamaguchi’s constant male hypothesis. We conclude that K. japonica clones are able to adjust their sex allocation patterns adaptively depending on the quality of resources in the galls.     

Removal of mercury using processes involving sulfuric acid during zinc production in an imperial smelting process (ISP) plant

Journal of Material Cycles and Waste Management - Mercury emissions from non-ferrous metal industries are a major environmental concern. Because of the large differences in mercury emission factors...     

A consideration for using workers’ heuristics to improve safety rules based on relationships between creative mental sets and rule-violating actions

This paper reports on the relationships between creative mental sets and rule-violating actions using questionnaires answered by 218 nursing workers. An exploratory factor analysis was conducted. The results revealed five factors of creative mental sets: curiosity, minutiae, inquiry, sensitivity, and courage. In addition, rule-violating actions were found to consist of three factors: violation of regulations, violation of local rules, and self-style. The results of multiple regression analyses showed a negative relation between curiosity and regular rule violation. Negative correlations were observed among minutiae, inquiry, and local rule violation. Furthermore, the mean score of local rule violation of a person who thinks that it is important for the work environment to offer high and excellent care is significantly higher than that of those who think that other environmental considerations are more important. The result elucidated the necessity of using workers’ heuristics in the process of improving safety rules as well as improving their acceptability to workers. This point is important and applicable not only in the field of patient safety management systems, but also in other fields.     

Maximal yields from multispecies fisheries systems: rules for systems with multiple trophic levels.

Increasing centralization of the control of fisheries combined with increased knowledge of food-web relationships is likely to lead to attempts to maximize economic yield from entire food webs. With the exception of predator-prey systems, we lack any analysis of the nature of such yield-maximizing strategies. We use simple food-web models to investigate the nature of yield- or profit-maximizing exploitation of communities including two types of three-species food webs and a variety of six-species systems with as many as five trophic levels. These models show that, for most webs, relatively few species are harvested at equilibrium and that a significant fraction of the species is lost from the web. These extinctions occur for two reasons: (1) indirect effects due to harvesting of species that had positive effects on the extinct species, and (2) intentional eradication of species that are not themselves valuable, but have negative effects on more valuable species. In most cases, the yield-maximizing harvest involves taking only species from one trophic level. In no case was an unharvested top predator part of the yield-maximizing strategy. Analyses reveal that the existence of direct density dependence in consumers has a large effect on the nature of the optimal harvest policy, typically resulting in harvest of a larger number of species. A constraint that all species must be retained in the system (a "constraint of biodiversity conservation") usually increases the number of species and trophic levels harvested at the yield-maximizing policy. The reduction in total yield caused by such a constraint is modest for most food webs but can be over 90% in some cases. Independent harvesting of species within the web can also cause extinctions but is less likely to do so.     

Carbonization of johkasou sludge using batch-type equipment

The carbonization of dehydrated johkasou sludge was examined using batch-type equipment. Based on the temperature changes in the carbonization room and the gas combustion room, the carbonization process was divided into three phases: phase I, drying the sludge; phase II, thermal decomposition of the dried sludge; phase III, after phase II. The times required for phases I and II were strongly correlated with the amounts of water and solid matter, respectively, in dehydrated sludge. The reduction rate of the sludge on completion of phase I was about 90% on average, and the decomposition rate of solid matter increased with time during phase II or phase II plus phase III until it reached about 50%. TOC concentration of the eluate from the carbonized sludge was used as an index to evaluate the progress of the carbonization process, and the highest temperature in the carbonization room was recognized as an important operational factor. The specific surface area and pore volume of carbonized sludge were smaller than those of charcoals and activated carbons by 1–3 orders of magnitude and 1–2 orders of magnitude, respectively. No elution of heavy metals was observed from any of the carbonized sludges examined. The reduced amount of carbon in dehydrated johkasou sludge was estimated to be about 25% of the decomposed organic matter.