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21.
Hideto Tsuji Hiroaki Sugiyama Yoshihiro Sato 《Journal of Polymers and the Environment》2012,20(3):706-712
Neat poly(l-lactic acid) (PLLA) and poly(d-lactic acid) (PDLA) films and PLLA/PDLA blend films were prepared by solution casting, and their photodegradation by UV-irradiation was investigated using wide-angle X-ray scattering (WAXS), gel permeation chromatography, differential scanning calorimetry, tensile testing, and polarized optical microscopy. The PLLA/PDLA blend film was more photodegradation-resistant than the neat PLLA and PDLA films when photodegradation was monitored by molecular weight, melting temperature, and WAXS crystalline peak positions. This indicates that the chains in both amorphous and crystalline regions of the PLLA/PDLA blend film were photo-cleavage-resistant compared to those of the neat PLLA and PDLA films. The changes in melting temperature and WAXS crystalline peak positions before and after photodegradation respectively indicated the increased crystalline lattice disorder and the decreased crystalline lattice sizes of the neat PLLA and PDLA films, whereas these changes were insignificant for the blend films. Photodegradation caused no significant change in tensile properties, with the exception of significant decreases in the tensile strength and elongation at break of PLLA/PDLA blend film. However, the tensile strength and elongation at break of the PLLA/PDLA blend film retained higher values compared to those of the neat PLLA and PDLA films during photodegradation. In spite of the slower photodegradation of the PLLA/PDLA blend film traced by M n, T m, and WAXS crystalline peak positions than that of neat PLLA and PDLA films, the rapid decrease in tensile strength and elongation at break of the former than that of the latter should be due to the highly-ordered structural difference between them, i.e., the three dimensional dry gel of the former and the spherulites of the latter. 相似文献
22.
Ohnuki T Aoyagi H Kitatsuji Y Samadfam M Kimura Y William Purvis O 《Journal of environmental radioactivity》2004,77(3):339-353
The uptake of plutonium(VI) and uranium(VI) by lichen biomass was studied in the foliose lichen Parmotrema tinctorum to elucidate the migration behavior of Pu and U in the terrestrial environment. Pu and U uptake by P. tinctorum averaged 0.040+/-0.010 and 0.055+/-0.015 g gdry (-1), respectively, after 96 h incubation with 4.0 x 10(14) mol 1(-1) Pu solutions of pH 3, 4 and 5. SEM observations showed that the accumulated Pu is evenly distributed on the upper and lower surfaces of P. tinctorum, in contrast to U(VI), which accumulated in both cortical and medullary layers. UV/VIS absorption spectroscopy demonstrates that a fraction of Pu(VI) in the solution is reduced to Pu(V) by the organic substances released from P. tinctorum, and the accumulated Pu on the surface is reduced to Pu(IV), while U(VI) keeps the oxidation state of VI. Since the solubility of Pu(IV) hydroxides is very low, reduced Pu(VI) does not penetrate to the medullary layers, but is probably precipitated as Pu(IV) hydroxides on the cortical lichen surface. It is concluded that the uptake and reduction of Pu(VI) by lichens is important to determine the mobilization and oxidation states of Pu in the terrestrial environment. 相似文献
23.
Thu Lan T. Nguyen Shabbir H. Gheewala Masayuki Sagisaka 《Journal of Cleaner Production》2010,18(5):412-418
One of the major justifications for bio-energy systems is their low greenhouse gas (GHG) emissions compared to fossil-energy ones. Transforming a sugar mill into a bio-energy plant would contribute to climate change mitigation via the extraction of renewable electricity and ethanol. This study takes the case of the sugar industry in Thailand and identifies scenario options that offer GHG reduction benefits. Improving efficiency in electricity generation from sugar cane residues e.g. excess bagasse and cane trash is such a beneficial option. Furthermore, extracting ethanol in a so-called bio-refinery, where the co-product stillage is utilized for energy, tends to magnify the potential benefit. The largest savings potential achieved with extracting ethanol from surplus sugar versus current practice in the sugar industry in Thailand amounts to 14 million tonnes CO2e a year. This cannot be realized in practice until the carbon debt from land conversion is repaid, which takes 4.5–7 years, assuming that the land converted is grassland. 相似文献
24.
Norio Miyamoto Tomoko Yamamoto Yoichi Yusa Yoshihiro Fujiwara 《Die Naturwissenschaften》2013,100(3):285-289
Bone-eating worms of the genus Osedax exclusively inhabit sunken vertebrate bones on the seafloor. The unique lifestyle and morphology of Osedax spp. have received much scientific attention, but the whole process of their development has not been observed. We herein report the postembryonic development and settlement of Osedax japonicus Fujikura et al. (Zool Sci 23:733–740, 2006). Fertilised eggs were spawned into the mucus of a female, and the larvae swam out from the mucus at the trochophore stage. Larvae survived for 10 days under laboratory conditions. The larvae settled on bones, elongated their bodies and crawled around on the bones. Then they secreted mucus to create a tube and the palps started to develop. The palps of O. japonicus arose from the prostomium, whereas the anterior appendages of other siboglinids arose from the peristomium. The recruitment of dwarf males was induced by rearing larvae with adult females. Females started to spawn eggs 6 weeks after settlement. 相似文献
25.
The photodegradation of polychlorinated dibenzo-p-dioxins (PCDDs), which include tetra- to octa-CDDs (TeCDD, PeCDD, HxCDD, HpCDD and OCDD), was carried out in the presence of Fe(II) and H2O2 mixed reagent. The degradation efficiency was strongly influenced by UV irradiation, and the initial concentrations of H2O2 and Fe(II). An initial TeCDD concentration of 10 ng l(-1) was completely degraded within 20 min under the optimum conditions. All PCDDs tested were successfully degraded by Fe(II)/H2O2/UV treatment and complete degradation of TeCDD, PeCDD and HxCDD was achieved within 120 min. PCDD photodegradation rates decreased with the number of chlorine atoms. The degradation process of TeCDD by this system seems to be initiated by an oxidative reaction (OH* radical attack) because less chlorinated DDs as intermediate products were not detected. From the Frontier electron density calculation, the first OH* radical attack positions on TeCDD were found to be four C atoms neighboring two O atoms. The decomposition of TeCDD gave 4,5-dichlorocatechol as an intermediate product. A TeCDD degradation scheme was proposed based on the identified intermediate and the values of Frontier electron density. Based on these results, Fe(II)/H2O2/UV system could be useful technology for the treatment of wastewater containing persistent pollutants such as dioxins and polychlorinated biphenyls. 相似文献
26.
Takeyasu M Iida T Tsujimoto T Yamasaki K Ogawa Y 《Journal of environmental radioactivity》2006,88(1):74-89
The concentrations and the concentration ratios of individual short-lived (222)Rn decay products ((214)Pb and (214)Bi) in rainwater were measured at Kumatori village (34.39 degrees N, 135.35 degrees E, approximately 70 m above sea level) in Osaka, Japan, by gamma-ray spectrometry using a low-background Ge detector. The dependence of the time variations of the concentrations and their ratios on rainfall rate was investigated. It was observed that the concentrations were negatively correlated with the rainfall rate in some rainfall events, and that there was no clear correlation in other rainfall events. The changes in the dependence of the concentration on the rainfall rate occurred after the passage of a cold front during a single rainfall event. The concentration ratios showed a weak negative correlation with the rainfall rate for most of the observed rainfall events. A scavenging model was designed in this study in order to explain the observation results. Based on the relationship between the concentrations of (214)Pb and (214)Bi in the rainwater and the rainfall rate for an individual rainfall event, the increase in the environmental gamma-ray dose rate from (214)Pb and (214)Bi deposited on the ground was calculated, and the calculated increase agreed well with that observed by the in situ measurement on flat ground. 相似文献
27.
Suzuki Y Nakamura M Otsuka Y Suzuki N Ohyama K Kawakami T Sato K Kajita S Hishiyama S Fujii T Takahashi A Katayama Y 《Chemosphere》2011,83(6):868-872
We characterized the ability of the cell free extract from polychlorinated dibenzo-p-dioxins degrading bacterium Geobacillus sp. UZO 3 to reduce even highly chlorinated dibenzo-p-dioxins such as octachlorodibenzo-p-dioxins in incineration fly ash. The degradation of 2,7-dichlorodibenzo-p-dioxin (2,7-DCDD) as a model dioxin catalyzed by the cell free extract from this strain implicates that the ether bonds of 2,7-DCDD molecule undergo reductive cleavage, since 4′,5-dichloro-2-hydroxydiphenyl ether and 4-chlorophenol were detected as intermediate products of 2,7-DCDD degradation. 相似文献
28.
Dry and wet deposition of water-insoluble dust and water-soluble chemical species during spring 2007 in Tsukuba,Japan 总被引:1,自引:0,他引:1
Yayoi Inomata Yasuhito Igarashi Masaru Chiba Yoshihiro Shinoda Hiroshi Takahashi 《Atmospheric environment (Oxford, England : 1994)》2009,43(29):4503-4512
Dry and wet depositions were sampled daily in Tsukuba, Japan, in spring 2007. Temporal variations in the dry and wet deposition fluxes of dust and water-soluble chemical species were controlled largely by air mass origin, the water vapor mixing ratio, and Asian dust events. The contribution of local sources to dry deposition of dust was large when the wind speed was high. Dry deposition fluxes of water-soluble chemical species were larger in humid air masses than in dry air masses. Wet deposition fluxes of dust and water-soluble chemical species indicated that air masses that passed over dust source regions and industrial regions became mixed with the maritime air masses over the coastal site of the Asian continent and western part of the Japanese islands. The total deposition of dust was 4220 mg m?2 month?1, and that of water-soluble chemical species ranged from 10 to 636 mg m?2 month?1. Wet deposition fluxes of the total deposition flux of dust accounted for 72% and those of water-soluble chemical species was for 72–96%. In particular, the largest wet deposition occurred during a single Asian dust event on 3 April. This event accounted for 23% (950 mg m?2 month?1) of the monthly dust deposition flux and for 2–28% (0.43–51 mg m?2 month?1) of the monthly deposition flux of water-soluble chemical species. This result implies that the wet deposition flux associated with even one sporadic Asian dust event can have extensive impacts on both terrestrial and oceanic ecosystems in East Asia. 相似文献
29.
Takafumi Fujita Takayuki Kawano Liwei Huang Yoshihiro Kojima Hitoki Matsuda Koichi Ushiroebisu 《Journal of Material Cycles and Waste Management》2007,9(1):15-20
To control the emission of halides into the environment, an experiment on the nonthermal plasma decomposition of the halides
CF4, CHF3, C2HCl3, and CHClF2 was conducted in a wire-in-tube corona reactor. It was found that the decomposition of C2HCl3 and CHClF2 was easy compared with the decomposition of CF4 and CHF3. With the addition of H2 in N2 gas, the decomposition ratio of CF4, C2HCl3, and CHClF2 increased. In contrast, the decomposition ratio of CHF3 in a hydrogen-rich atmosphere was lower than that in an N2 atmosphere. It was demonstrated that the yields of HF and/or HCl formed during halide decomposition clearly increased in
the presence of H2 in N2 gas. Furthermore, in order to prevent the production of unwanted products from halide decomposition, a combination of plasma
decomposition and in situ alkaline absorption was devised by coating a layer of Ca(OH)2 onto the surface of the grounding electrode. It was demonstrated that the Ca(OH)2 sorbent played an effective role as a scavenger, participating in halide decomposition by capturing reaction products such
as HCl and HF, therefore resulting in increased halide decomposition. 相似文献
30.
Naoto Mihara Dalibor Kuchar Yoshihiro Kojima Hitoki Matsuda 《Journal of Material Cycles and Waste Management》2007,9(1):21-26
From the point of view of a sustainable and environment-friendly society based on the recycling of material resources, it
is preferable to utilize waste gypsum as a substitute for lime, which is currently produced by the calcination of limestone.
In the present work, the reductive decomposition of CaSO4 was investigated under an atmosphere of CO: 2 vol%, CO2: 30 vol%, with N2 as a carrier gas without and with the addition of SiO2, Al2O3, or Fe2O3. It was found that the decomposition temperature of CaSO4 was significantly reduced from 1673 K to 1223 K when only 5 wt% Fe2O3 was added to CaSO4. In the case of the addition of SiO2 or Al2O3 to CaSO4, the decomposition temperature was reduced from 1673 K to 1623 K. This was due to the formation of composite oxides (calcium
ferrite, calcium silicate, or calcium aluminate) during the reaction of CaSO4 with the additives at a lower temperature. In addition, the formation of unfavorable product CaS was inhibited in the presence
of 5 wt% Fe2O3, and this inhibition effect further increased as the addition of Fe2O3 was increased. In contrast, no significant effect on the inhibition of CaS formation was observed on the addition of SiO2 or Al2O3. 相似文献