垃圾堆填区渗出液对干旱季节树苗生长的影响

本试验于１９９４年７月至１月在香港望后石垃圾堆填区进行,研究了垃圾堆填区渗出液浇灌对几种亚热带树种生长及其生理学过程的影响．结果表明,在高温低湿、植物遭受水分亏缺的条件下,应用适当浓度的垃圾堆填区渗出液浇灌同水灌和肥水灌溉类似,可显著地提高树苗的移栽成活率,促进树苗的生长,尤其对耐干旱能力低的树种,其效果更为显著．与对照相比,用适当浓度的渗出液或水浇灌显著地改善植株的水分关系,降低叶片的脱落酸（ＡＢＡ）含量,促进气孔的开放．另外,处理植株叶片的光合特性也得到了不同程度的改善．根据以上结果,作者认为,在干旱季节植物遭受严重水分亏缺的条件下,应用适当浓度的垃圾堆填区渗出液浇灌可显著地缓解干旱对树苗生长的影响,为综合治理垃圾堆填区渗出液提供了一条经济、实用和可行的途径．     

Mechanical treatment of automobile shredder residue for its application as a fuel

Enforcement of the Automobile Recycling Law in Japan requires utilization of automobile shredder residue (ASR). However, the high contents of copper (∼5%) and chlorine (∼1%) in ASR stand in the way of practical application. We studied methods for the removal of copper and chlorine from ASR so that it could be utilized as a fuel. By compression of the ASR for solidification with an extruder, the polyvinylchloride (PVC) that covered electrical cables was softened and stripped from the copper wire. The solidified ASR was comminuted with cutter mills and classified by dry density separation. The copper content of the obtained light products was 0.2%–0.5%. Furthermore, we studied the possibility of dechlorination of the ASR by mechanochemical (MC) activation. The light product of the ASR was milled with CaO or CaCO₃. The chlorine content decreased to about one-tenth of the original value after MC activation over 8 h. Therefore, the combined processing of softening–stripping and comminution liberated the PVC-covered cables and decreased the copper content of the ASR. In addition, dechlorination of the ASR was also possible by MC activation with the addition of calcium compounds.     

Pharyngeal aspiration of single-wall carbon nanotubes aggravates allergic reaction to inhaled ovalbumin in mice

Single-wall carbon nanotubes are a major type of nano-objects that have industrial applications such as fuel cells. In this study, four types of single-wall carbon nanotubes and their abilities to aggravate allergic reactions were examined: those containing Fe, those containing Ni, and the corresponding purified metal-free ones. These were administered to mice via pharyngeal aspiration. Subsequently, the mice inhaled ovalbumin a total of eight times over three weeks. After inhalation of ovalbumin, the concentrations of total immunoglobulin E and ovalbumin-specific immunoglobulin E in serum increased in mice treated with purified metal-free and Fe containing single-wall carbon nanotubes while those containing Ni did not affect total and ovalbumin-specific immunoglobulin E levels. Additionally, the purified metal-free and Fe containing nanotubes caused the gene expression of heme oxygenase-1, chemokine (C-X-C motif) ligand 2, and tumor necrosis factor-α, suggesting that some kinds of single-wall carbon nanotubes have the potential to aggravate allergic reactions via oxidative stress and inflammation. Incorporated metals do not seem to be involved in the aggravation of allergic reactions. Other physical properties, such as fiber length and aggregation state, may be involved in enhancing allergic reactions.     

Evaluation of antimicrobial agents for veterinary use in the ecotoxicity test using microalgae

The influence of antimicrobial agents approved as veterinary drugs in Japan on the growth of green algae, Selenastrum capricornutum and Chlorella vulgaris, was studied in accordance with the OECD guidelines for testing chemicals. Among the agents tested, growth inhibitory activity was very varied, i.e. erythromycin showed the strongest activity (EC₅₀, 50% effective concentration, =0.037 mg/l), sulfa drugs had activity to some extent (EC₅₀s of sulfamethoxazole, sulfadiazine, and sulfadimethoxine were 1.5, 2.2, and 2.3 mg/l, respectively), but ampicillin and cefazolin did not inhibit growth (EC₅₀s > 1000 mg/l). We also investigated synergistic effect of combining sulfa drugs with trimethoprim or pyrimethamine, which are commonly used as a combined drug. By adding trimethoprim, the growth inhibitory activity of sulfamethoxazole and sulfadiazine was significantly enhanced. Growth inhibition by sulfa drugs was reduced by the addition of folic acid, indicating that they inhibit folate synthesis in green algae.     

Improvement in the feeding method to an inclined conveyor designed for the recycling of foundry sand

 The goal of the inclined conveyor method for particle shape separation is to process a large amount of feed material for recycling technology. The high feed rate has been achieved because the movement of particles is faster than for other previously introduced equipment. The separation performance of the apparatus was tested with foundry sand. A large amount of sand was treated, and various processing capacities were studied experimentally. The feed method was improved from point to line with wide troughs to process the higher feed rate. We succeeded in attaining a feed rate of 1.49 × 10⁻³ kg/s with a 0.3-m trough. The space filling, which was an important factor in deciding the capacity of the feed rate, was defined. This method is useful for any kind of line-feed method. Received: March 25, 2002 / Accepted: August 5, 2002