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81.
Collins RN Saito T Aoyagi N Payne TE Kimura T Waite TD 《Journal of environmental quality》2011,40(3):731-741
Time-resolved laser fluorescence spectroscopy (TRLFS) is a useful means of identifying certain actinide species resulting from various biogeochemical processes. In general, TRLFS differentiates chemical species of a fluorescent metal ion through analysis of different excitation and emission spectra and decay lifetimes. Although this spectroscopic technique has largely been applied to the analysis of actinide and lanthanide ions having fluorescence decay lifetimes on the order of microseconds, such as UO , Cm, and Eu, continuing development of ultra-fast and cryogenic TRLFS systems offers the possibility to obtain speciation information on metal ions having room-temperature fluorescence decay lifetimes on the order of nanoseconds to picoseconds. The main advantage of TRLFS over other advanced spectroscopic techniques is the ability to determine in situ metal speciation at environmentally relevant micromolar to picomolar concentrations. In the context of environmental biogeochemistry, TRLFS has principally been applied to studies of (i) metal speciation in aqueous and solid phases and (ii) the coordination environment of metal ions sorbed to mineral and bacterial surfaces. In this review, the principles of TRLFS are described, and the literature reporting the application of this methodology to the speciation of actinides in systems of biogeochemical interest is assessed. Significant developments in TRLFS methodology and advanced data analysis are highlighted, and we outline how these developments have the potential to further our mechanistic understanding of actinide biogeochemistry. 相似文献
82.
Mifuyu Ogawa Yuichi Yamaura Shin Abe Daisuke Hoshino Kazuhiko Hoshizaki Shigeo Iida Toshio Katsuki Takashi Masaki Kaoru Niiyama Satoshi Saito Takeshi Sakai Hisashi Sugita Hiroyuki Tanouchi Tatsuya Amano Hisatomo Taki Kimiko Okabe 《Environmental monitoring and assessment》2011,177(1-4):85-94
An alkaline comet assay and a micronucleus test were carried out on erythrocytes of the European chub, Squalius cephalus L., collected in spring and autumn in 2005 and 2006 at three sampling sites in River Sava, near Zagreb, Croatia. The results of comet assay showed the lowest genotoxic influence at the least polluted site, while higher DNA damage was observed at the polluted sites. Although the basal levels of DNA damage were elevated, a clear gradation of DNA damage was found due to pollution intensity in all sampling periods. The lowest cytogenetic damage as revealed by the micronucleus test (MNT) was observed as well at the least polluted site. High variations in MN frequency were observed between sampling periods, although the number of micronucleated erythrocytes was consistently the highest one at the polluted site. The comet assay as a biomarker of genotoxic effect exhibited higher sensitivity in discriminating the genotoxic capacity of studied polluted sites while the MNT was less sensitive. However, both tests should be used together in biomonitoring studies because they can reveal different aspects of DNA damage; comet assay, the early event of genotoxic exposure, and MNT, its final result as a mutagenic potential. 相似文献
83.
Biodegradability and Biodegradation of Polyesters 总被引:4,自引:0,他引:4
A variety of biodegradable plastics have been developed in order to obtain useful materials that do not cause harm to the
environment. Among the biodegradable plastics, aliphatic polyesters such as: poly(3-hydroxybutyrate) (PHB), poly(ε-caprolactone)
(PCL), poly(butylene succinate) (PBS), and poly(l-lactide) (PLA) have become the focus of interest because of their inherent biodegradability. However, before their widespread
applications, comprehensive studies on the biodegradability and biodegradation mechanisms of these polyesters are necessary.
Thus, this paper describes the degradation mechanisms and the effects of various factors on the degradation of polyesters.
The distribution of polymer-degrading microorganisms in the environment, different microorganisms and enzymes involved in
the degradation of various polyesters are also discussed. 相似文献
84.
Charles U. Ugwu Yutaka Tokiwa Hideki Aoyagi 《Journal of Polymers and the Environment》2012,20(1):254-257
The feasibility of utilizing non edible rice (broken rice) for production of fine materials such as poly(3-hydroxybutyrate)
(PHB) was considered as one of the alternative ways of keeping the environment clean for sustainable development. Thus, production
of PHB from broken rice by simultaneous saccharification and fermentation (SSF) was investigated. During the SSF process,
the rice (15% w/v) material was hydrolyzed to glucose, which was utilized by Cupriavidus necator for growth and production of PHB. The PHB content reached 38% at 58 h fermentation. The PHB had weight average molar mass
(Mw) and polydipersity index of 3.82 × 105 (g/mol) and 4.15, respectively. Differential calorimetric scan of the PHB showed a melting temperature (Tm) of 176 °C. Given
that the PHB was a homopolymer (which consisted of (R)-3-hydroxybutyric acid monomers), it was thought that broken rice could be a raw material for production of both PHB and
(R)-3-hydroxybutyric acid. This SSF process would not only help in the utilization of broken rice or non edible rice, but would
also serve as a model for utilization of other raw materials that contain starch for production of PHB. 相似文献
85.
86.
An efficient sampling method for dioxins from flue gas, an efficient automatic purification and fractionation method by a new HPLC system using a sulfuric acid-silica/silica column, a Nitro column and a PGC column, and sensitive determination method by an economical HRGC/LRMS using a programmable temperature vaporization (PTV) injector were developed. It was confirmed that the dioxins could be easily collected by the proposed simple sampling train consisting of only two bottles, and the extracted sample could be purified sufficiently and separated as mono-ortho PCBs, non-ortho PCBs and PCDDs/PCDFs completely with the proposed HPLC system. The peak areas of GC/MS were increased linearly with the injection volume up to 40 microl by the PTV technique, and the sensitivity could be increased to 20 times higher than usual. This convenient measuring method can drastically reduce operation time, consumption of hazardous solvent and cost. 相似文献
87.
The atmospheric concentration of NO2 in Lima, Peru was measured through 1 year using passive samplers. The concentration was stable and evident seasonal change was not observed. Also, the distribution of NO2 concentration in entire Lima was monitored twice in different seasons. The average NO2 concentrations at 33 and 27 sites of these monitoring were 17.1 and 15.3 ppb, respectively. NO2 distribution was high in the downtown area and decreased gradually with distance from there. The wind that almost always blew from the ocean had a great influence on it. High NO2 level and the change of CO concentration suggest that the residential area in the northeast side forms a topological channel among hills to blow out the pollutants from the downtown area. 相似文献
88.
Recycle technology for waste plastics containing polyvinyl chloride (PVC) has been developed in the Hokkaido National Industrial
Research Institute for the production of solid and liquid fuel, and has established a recycling process which includes a dechlorination
process for PVC plastics, and a two-stage catalytic pyrolysis process for plastics using zeolite catalysts. The dechlorination
equipment consists of a two-axis screw extruder with a heating element, which can remove chlorine up to 99.9 wt. % from PVC
containing plastics as hydrogen chloride. The product had about 44 000 kJ/kg calorific value and was fed into the next oil
production process, although it could also be used as a solid fuel. Natural and synthetic zeolite were used as catalysts for
the two-stage catalytic process, which produced a light oil with a boiling point which was between those of kerosene and gasoline.
The yield of this oil reached 82 wt. %. The chemical type was analyzed using liquid chromatography, and was found to have
many aromatic compounds. These technologies make it possible to produce a nonpolluting, high-calorie solid fuel and a liquid
fuel very efficiently.
Received: July 19, 2000 / Accepted: September 21, 2000 相似文献
89.
Teruyuki Kobayashi Akinori Sugiyama Yoshiyuki Kawase Terumi Saito Joris Mergaert Jean Swings 《Journal of Polymers and the Environment》1999,7(1):9-18
To determine the properties of enzymes from bacteria that degrade polypropiolactone (PPL), we isolated 13 PPL-degrading bacteria from pond water, river water, and soil. Nine of these strains were identified as Acidovorax sp., three as Variovorax paradoxus, and one as Sphingomonas paucimobilis. All the isolates also degraded poly(3-hydroxybutyrate) (PHB). A PPL-degrading enzyme was purified to electrophoretical homogeneity from one of these bacteria, designated Acidovorax sp. TP4. The purified enzyme also degraded PHB. The molecular weight of the enzyme was estimated as about 50,000. The enzyme activity was inhibited by diisopropylfluorophosphate, dithiothreitol, and Triton X-100. The structural gene of the depolymerase was cloned in Escherichia coli. The nucleotide sequence of the cloned DNA fragment contained an open reading frame (1476 bp) specifying a protein with a deduced molecular weight of 50,961 (491 amino acids). The deduced overall sequence was very similar to that of a PHB depolymerase of Comamonas acidovorans YM1609. From these results it was concluded that the isolated PPL-degrading enzyme belongs to the class of PHB depolymerases. A conserved amino acid sequence, Gly-X1-Ser-X2-Gly (lipase box), was found at the N-terminal side of the amino acid sequence. Site-directed mutagenesis of the TP4 enzyme confirmed that 20Ser in the lipase box was essential for the enzyme activity. This is the first report of the isolation a PHB depolymerase from Acidovorax. 相似文献
90.
Guang Hao Chen Wun Jern Ng Hiroaki Ozaki Yutaka Terashima 《Resources, Conservation and Recycling》1994,11(1-4)
The concentration of dissolved oxygen (DO) strongly influences the performance of aerobic biofilm reactors because organic oxidation is limited by the availability of oxygen. However, it is not necessary to maintain a high DO level in the reactors in order to overcome this limitation. Excessive aeration wastes energy. Therefore, the determination of the onset of DO limitation against organic substrate removal in aerobic biofilm reactors is important for their effective operation. This study is aimed at developing an expression to determine the onset of DO limitation and hence to control the aeration system. The expression developed is as follows:
, where Sb and Cb are the bulk concentrations of organic substrate and DO, respectively; Dws and Dwc are the diffusion coefficients of organic substrate and oxygen in the reactors respectively; and Rb is an overall ratio of oxygen consumption to organic substrate removal in the reactors. The latter is the key parameter in the equation, and is determined by the characteristics of the substrate, biofilm, and reactor. In order to measure the value of Rb, the authors have developed a micro-biofilm reactor. The value of Rb was determined to be 0.13 (mg O2 mg−1 CODcr) for glucose removal with this reactor. The equation has, subsequently, been verified with data from batch and continuous experiments. 相似文献