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191.
Toshiro Tsuji Yoshiki Tanaka Hironori Itoh 《Journal of Material Cycles and Waste Management》2001,3(1):2-7
Plastic pellets of polyethylene (PE), polypropylene (PP), and polystyrene (PS) were gasified in a two-stage thermal degradation
process. The first stage is the conversion of polyolefins to distilled oils using a melting vessel. In the second stage, the
oils from the first stage are gasified using a tubular reactor. The distilled oil yields of PE, PP, and PS in the first stage
were 84, 89, 92 wt%, respectively, each at 470°C. The total gas yields of PE, PP, and PS in the second stage were 80, 74,
and 6.2 wt%, respectively, each at 800°C. The main components of the product gas for PE and PP were methane and olefins such
as ethene and propene. Some aromatic oils, including benzene, toluene, and xylene, were also produced as by-products. The
amount of carbonaceous residue, or coke, was very low (less than 1 wt%). By dividing the process into two stages, the coking
rate was considerably reduced compared with direct gasification of the polyolefins.
Received: July 19, 2000 / Accepted: September 17, 2000 相似文献
192.
193.
Physical properties and biodegradability of blends containing poly(ε-caprolactone) and tropical starches 总被引:1,自引:0,他引:1
Hardaning Pranamuda Yutaka Tokiwa Hideo Tanaka 《Journal of Polymers and the Environment》1996,4(1):1-7
In order to assess feasibility of tropical starches (sago and cassava starches) as biodegradable plastic materials, blending with poly(-caprolactone) (PCL), a biodegradable polymer, was carried out. It was confirmed that the physical properties (tensile strength and elongation) of PCL/sago and PCL/cassava blends were similar to those of PCL/corn blend, suggesting that sago and cassava starches can also be blended with PCL for production of biodegradable plastic. However, the properties of all PCL/starch blends were still low compared with those of polyethylene. Enzymatic degradability evaluation showed that lipase degradation of PCL and-amylase degradation of starch increased as the starch content in the blend increased. Burial test of the blends for 1, 3, and 5 months was carried out and the rate of degradation of the PCL/sago blend was confirmed to be slower than those of PCL/corn and PCL/cassava blends. Observation of the film blends structure by scanning electron microscope revealed that the starch was dispersed in a PCL continuous phase. Furthermore, changes in the film surface before and after enyzme treatments were observed. 相似文献
194.
Nobutoshi Tanaka Yasumasa Tojo Toshihiko Matsuto 《Journal of Material Cycles and Waste Management》2005,7(2):104-111
This article focuses on the historical development of landfill technology since the beginning of the nineteenth century in Japan. The regulations and guidelines that form a framework for the technology are reviewed, and the historical background and the current state of Japanese municipal solid waste (MSW) management are described. Through the analysis of data collected from facility leaflets, changes in the leachate treatment system are surveyed. Finally, the concept of the “sustainable bioreactor landfill with low organics” is proposed. 相似文献
195.
Waste management for a sustainable society 总被引:1,自引:0,他引:1
196.
This paper explores statistical modeling of forest area with two covariates. The forest coverage ratio of grid-cell data was modeled by taking human population density and relief energy into account. The likelihood of the forest ratios was decomposed into the product of two likelihoods. The first likelihood was due to trinomial logistic distributions on three categories: the forest ratios take zero, or one, or values between zero and one. The second one was due to a logistic-normal regression model for the ratios between zero and one. This model was applied to real grid-cell data and it fit better than zero-inflated beta regression models. 相似文献
197.
Masakazu Hori Takao Suzuki Yaowaluk Monthum Tippamas Srisombat Yoshiyuki Tanaka Masahiro Nakaoka Hiroshi Mukai 《Marine Biology》2009,156(7):1447-1458
Seagrass species function as typical foundation species that unifies most ecosystem processes. This ecosystem role depends
largely on the morphological characteristics and structural complexity of seagrass beds, including their ecological importance
for fish species. This study examined relationships between seagrass bed characteristics and associated fish communities in
mixed seagrass beds. Correspondence analysis (CA) and canonical correlation analysis (CCoA) were performed to estimate relationships
for individual seagrass bed characteristics. The CCoA results revealed that species richness and three-dimensional structure
of seagrass had great effect on the biomass and richness of the associated fish community. The CA results revealed that the
relative importance of seagrass bed characteristics differed among fish functional groups including fishes appearing on the
surface of, inside, and on the bottom of seagrass beds. The fishes found on the surface of the beds preferred beds with low
seagrass biomass and high three-dimensional structure, those inside the beds preferred beds with high seagrass biomass and
high three-dimensional structure, and those on the bottom of the beds preferred locations with low seagrass biomass and low
three-dimensional structure. The results of this study provide compelling evidence that seagrass beds with high species diversity
and high three-dimensional structure, but intermediate biomass, may provide the great benefit to the associated fish community.
Such niche complementarity among fishes may be a process facilitated by seagrass diversity for secondary production as an
ecosystem functioning. 相似文献
198.
Stacy K. Tanaka Jay R. Lund 《Journal of the American Water Resources Association》2003,39(6):1509-1519
ABSTRACT: Exports from the Sacramento‐San Joaquin Delta are an important source of water for Central Valley and Southern California users. The purpose of this paper is to estimate and analyze the effects increased exports to south of Delta users would have on the Sacramento Valley economy and water management if water were managed and reallocated for purely economic benefits, as if there were an ideal Sacramento Valley water market. Current Delta exports of 6,190 thousand acre‐feet per year were increased incrementally to maximum export pumping plant capacities. Initial increases in Delta exports did not increase regional water scarcity, but decreased surplus Delta flows. Further export increases raised agricultural scarcity. Urban users suffer increased scarcity only for exports exceeding 10,393 taf/yr. Expanding exports raises the economic value of expanding key facilities (such as Engle bright Lake and South Folsom Canal) and the opportunity costs of environmental requirements. The study illustrates the physical and economic capacity of the Sacramento Valley to further increase exports of water to drier parts of the state, even within significant environmental flow restrictions. More generally, the results illustrate the physical capacity for greater economic benefits and flexibility in water management within environmental constraints, given institutional capability to reoperate or reallocate water resources, as implied by water markets. 相似文献
199.
In the post-genome-sequencing era, emerging genomic technologies are shifting the paradigm for drug discovery and development.
Nevertheless, drug discovery and development still remain high-risk and high-stakes ventures with long and costly timelines.
Indeed, the attrition of drug candidates in preclinical and development stages is a major problem in drug design. For at least
30% of the candidates, this attrition is due to poor pharmacokinetics and toxicity. Thus, pharmaceutical companies have begun
to seriously re-evaluate their current strategies of drug discovery and development. In that light, we propose that a transport
mechanism-based design might help to create new, pharmacokinetically advantageous drugs, and as such should be considered
an important component of drug design strategy. Performing enzyme- and/or cell-based drug transporter, interaction tests may
greatly facilitate drug development and allow the prediction of drug–drug interactions. We recently developed methods for
high-speed functional screening and quantitative structure–activity relationship analysis to study the substrate specificity
of ABC transporters and to evaluate the effect of genetic polymorphisms on their function. These methods would provide a practical
tool to screen synthetic and natural compounds, and these data can be applied to the molecular design of new drugs. In this
review article, we present an overview on the genetic polymorphisms of human ABC transporter ABCG2 and new camptothecin analogues
that can circumvent AGCG2-associated multidrug resistance of cancer. 相似文献
200.
Because of limited space, the siting and construction of a new SWM facility is a big challenge in Japan. An SWM facility should be socially accepted as well as environmentally and economically sound. This study aimed to investigate people's concerns about SWM facilities and their attitudes towards such facilities. A questionnaire was designed based on literature reviews and was sent to residents in three municipalities with different backgrounds. The questions covered concerns on the impact of an SWM facility, management aspects, unfairness of facility siting, and attitudes to facility construction. Of the many concerns, "pollution and health effect" had the highest rating, followed by "reliability", "damage to nature" and "cost". The rating was different between municipalities, reflecting their geographic and social backgrounds. Using factor analysis, correlations among concerns were analyzed, and five principal components were extracted, namely "pollution", "nuisance", "facility management", "planning of facility", and "merit/demerit". Although obvious correlations were not found between individual items of concern and attitudes to construction of a facility, the discriminant analysis indicated dominant concerns of attitudes, but the disagreement between actual impact and citizens were found. As for attributes, the "opposed" attitude decreased for residents who had visited an SWM facility, even if they had only seen it from outside. 相似文献