Synthesis and biodegradation of poly(γ-butyrolactone-co-l-lactide)

Biodegradable polyesters were synthesized by ring-opening copolymerization of -butyrolactone (BL) and its derivatives withl-lactide (LLA). Although tetraphenyl tin was the main catalyst used, other organometallic catalysts were used as well.¹H and¹³C NMR spectra showed that poly(BL-co-LLA)s were statistical and that their number-average molecular weights were as high as 7×10⁴. The maximum BL content obtained from copolymerization BL/LLA was around 17%. TheT _m andT _g values of the copolymers showed a gradual depression with an increase in BL content. NoT _m was obtained for the copolymers containing more than 13 mol% BL. The biodegradability of the copolyesters was evaluated by enzymatic hydrolysis and nonenzymatic hydrolysis tests. The enzymatic hydrolysis was carried out at 37°C for 24 h using lipases fromRhizopus arrhizus andR. delemar. Hydrolyses by both lipases showed that an increase in BL content of the copolymer resulted in enhanced biodegradability. Nonenzymatic accelerated hydrolysis of copolymers at 70°C was found to increase proportionally to their exposure time. The hydrolysis rate of these copolymers was considerably faster than that of PLLA. The higher hydrolyzability was recorded for the BL-rich copolymers. The copolymerization of -methyl--butyrolactone (MBL) or -ethyl--butyrolactone (EBL) with LLA resulted in relatively LA-rich copolymers.     

Electrochemical oxidation of bisphenol A. Application to the removal of bisphenol A using a carbon fiber electrode

Leachate samples with a high strength of ammonium-nitrogen (NH4+-N) were collected from a local landfill site in Hong Kong. Two experiments were carried out to study (1) the inhibition of microbial activity of activated sludge by NH4+-N and (2) the chemical precipitation of NH4+-N from leachate as a preliminary treatment prior to the activated sludge process. The experimental results demonstrated that the efficiency of COD removal decreased from 97.7% to 78.1%, and the dehydrogenase activity of activated sludge decreased from 9.29 to 4.93 microg TF/mg MLSS, respectively, when the NH4+-N concentration increased from 53 to 800 mg/l. The experiment also demonstrated that the NH4+-N in the leachate can be quickly precipitated as MgNH4PO4 x 6H2O after addition of MgCl2 x 6H2O + Na2HPO4 x 12H2O. The NH4+-N concentration was reduced from 5618 to 112 mg/l within 15 min when a molar ratio of Mg2+:NH+:PO4(3-) = 1:1:1 was used. The optimum pH to reach the minimum solubility of MgNH4PO4 x 6H2O was found to be in the range of 8.5-9.0. Attention should be given to the high salinity formed in the treated leachate by using MgCl2 x 6H2O + Na2HPO4 x 12H2O, which may affect microbial activity in the following biological treatment processes. Using two other combinations of chemicals [MgO + 85%H3PO4 and Ca(H2PO4)2 x H2O + MgSO4 x 7H2O] could minimise salinity generation after precipitation, while they were less efficient for NH4+-N removal.     

Glycosylation of bisphenol A by freshwater microalgae

The endocrine disruptor bisphenol A (BPA, 4,4'-isopropylidenediphenol) is used to manufacture polycarbonate plastic and epoxy resin linings of food and beverage cans, and the residues from these products are then sometimes discharged into rivers and lakes in waste leachates. However, the fate of BPA in the environment has not yet been thoroughly elucidated. Considering the effect of BPA on aquatic organisms, it is important that we estimate the concentration of BPA and its metabolites in the aquatic environment, but there are few data on the metabolites of BPA. Here, we focused on freshwater microalgae as organisms that contribute to the biodegradation or biotransformation of BPA in aquatic environments. When we added BPA to cultures of eight species of freshwater microalgae, a reduction in the concentration of BPA in the culture medium was observed in all cultures. BPA was metabolized to BPA glycosides by Pseudokirchneriella subcapitata, Scenedesmus acutus, Scenedesmus quadricauda, and Coelastrum reticulatum, and these metabolites were then released into the culture medium. The metabolite from P. subcapitata, S. acutus, and C. reticulatum was identified by FAB-MS and (1)H-NMR as bisphenol A-mono-O-beta-d-glucopyranoside (BPAGlc), and another metabolite, from S. quadricauda, was identified as bisphenol A-mono-O-beta-d-galactopyranoside (BPAGal). These results demonstrate that freshwater microalgae that inhabit universal environments can metabolize BPA to its glycosides. Because BPA glycosides accumulate in plants and algae, and may be digested to BPA by beta-glycosidase in animal intestines, more attention should be given to levels of BPA glycosides in the environment to estimate the ecological impact of discharged BPA.     

Indigo carmine removal by charcoal from rice bran as an agricultural by-product

On the utilization of agricultural by-product, charcoal from rice bran was produced. The adsorption characteristics of indigo carmine onto charcoals from rice bran were investigated by the batch method. The yield and surface area of charcoal were decreased and increased with increase of carbonization temperature, respectively. The removal ratio of indigo carmine was high with the charcoal carbonized at higher temperature. In the relationship between the amount of indigo carmine adsorbed and the square root of elapsed time, a good linearity was recognized. The kinetic constant of adsorption removal for indigo carmine was rapid in the charcoal carbonized at higher temperature. The adsorption characteristics for indigo carmine removal by charcoal from rice bran were dominated by the value of their surface area.     

Recovery of seven kinds of cfc and cfc replacements on high‐surface area activated carbon

The adsorption isotherms, the constants of the Dubinin—Radushkevich plots, and the constants of the Langmuir plots of chlorofluorocarbon (CFC) and CFC replacements on high‐surface area activated carbon were investigated to estimate the recovery efficiency of CFC and CFC replacements. The adsorption and desorption of HFC134a on a high‐surface area activated carbon was much easier than that of CFC 113 and the CFC replacements. The recovery efficiency of CFC replacements depends on the hydrogen atoms in molecule. It is possible that the saturated amount adsorbed in the pores or on the surface of the activated carbon could be evaluated by the W_s constant of the the Langmuir equation and the W_o constant of the Dubinin‐Radushkevich equation. The a constant of the Langmuir equation and the BE_o constant of the Dubinin‐Radushkevich equation depend on the molecular composition.     

The growing role of web‐based geospatial technology in disaster response and support

This paper examines changes in disaster response and relief efforts and recent web‐based geospatial technological developments through an evaluation of the experiences of the Center for Geographic Analysis, Harvard University, of the Sichuan (2008) and Haiti (2010) earthquake responses. This paper outlines how conventional GIS (geographic information systems) disaster responses by governmental agencies and relief response organisations and the means for geospatial data‐sharing have been transformed into a more dynamic, more transparent, and decentralised form with a wide participation. It begins by reviewing briefly at historical changes in the employment of geospatial technologies in major devastating disasters, including the Sichuan and Haiti earthquakes (case studies for our geospatial portal project). It goes on to assess changes in the available dataset type and in geospatial disaster responders, as well as the impact of geospatial technological changes on disaster relief effort. Finally, the paper discusses lessons learned from recent responses and offers some thoughts for future development.     

Comparison of polybrominated diphenyl ethers in fish, vegetables, and meats and levels in human milk of nursing women in Japan

At present, little is known about the occurrence of polybrominated diphenyl ethers (PBDEs) in fish and food products sold in Japan. To investigate whether human exposure to PBDEs through the diet is significant, the concentrations of PBDEs were determined in fish and in meat and vegetables sold in two food markets in the city of Hirakata, Osaka prefecture. The concentrations of PBDEs in the breast milk of 12 primiparae nursing women at one month after delivery also were determined to ascertain the relationship between the levels found in the diet and levels in humans. sigma PBDE concentrations ranged between 21 and 1650 pg/g fresh weight in the edible tissues of five species of fish and one shellfish species. The highest concentrations were measured in yellow-fin tuna, followed by short-necked clam, salmon, yellowtail, mackerel and young yellowtail. Interestingly, sigma PBDE concentrations were not statistically significantly different in two cultured mackerel samples from Japan and mackerel collected from northern European waters. sigma PBDE concentrations in beef, pork and chicken meat (ranging between 6.25 and 63.6 pg/g fresh weight) and in three different vegetables (ranging between 38.4 and 134 pg/g fresh weight) were significantly lower than the concentrations in fish. In human milk, sigma PBDE concentrations ranged between 668 and 2840 pg/g lipid basis, which is comparable to the levels in populations of nursing women reported in Sweden and elsewhere. There was a strong positive relationship between PBDE concentrations in human milk and dietary intake of fish and shellfish, which was established in the women from responses to a questionaire on food consumption habits. The results of this study of food products commonly consumed in Japan and the levels found in nursing women raise a concern about low level PBDE contamination of fish and other foods intended for human consumption.     

Measurements of aerosol optical properties in central Tokyo during summertime using cavity ring-down spectroscopy: Comparison with conventional techniques

A highly sensitive cavity ring-down spectrometer (CRDS) was used to monitor the aerosol extinction coefficient at 532 nm. The performance of the spectrometer was evaluated using measurements of nearly monodisperse polystyrene particles with diameters between 150 and 500 nm. By comparing the observed results with those determined using Mie theory, the accuracy of the CRDS instrument was determined to be >97%, while the upper limit for the precision of the instrument was estimated to be 0.6–3.5% (typically 2%), depending on the particle number concentration, which was in the range of 30–2300 particles cm^?3. Simultaneous measurements of the extinction (b_ext), scattering (b_sca) and absorption (b_abs) coefficients of ambient aerosols were performed in central Tokyo from 14 August to 2 September 2007 using the CRDS instrument, two nephelometers and a particle/soot absorption photometer (PSAP), respectively. The value of b_ext measured using the CRDS instrument was compared with the sum of the b_sca and b_abs values measured with a nephelometer and a PSAP, respectively. Good agreement between the b_ext and b_sca + b_abs values was obtained except for data on days when high ozone mixing ratios (>130 ppbv) were observed. During the high-O₃ days, the values for b_sca + b_abs were ～7% larger than the value for b_ext, possibly because the value for b_abs measured by the PSAP was overestimated due to interference from coexisting non-absorbing aerosols such as secondary organic aerosols.     

Properties and biodegradability of chain-extended copoly(succinic anhydride/ethylene oxide)

Chain-extension reactions were carried out using titanium-iso-propoxide (TIP) as a catalyst for a series of polyesters or copolyesterethers with low molecular weights (M _n =1500–10,000) synthesized by the ring-opening copolymerization of succinic anhydride (SA) with ethylene oxide (EO). The copolymers having aM _n from 25,000 to 50,000 of different properties were obtained. Both the melting point (T _m ) and the fusion heat (H), which indicate the crystallinity of the copolymers, rose with an increase in SA content in the copolymers. Semitransparent films were prepared by compression molding of the copolymers. The biodegradation of the copolymer films was evaluated by enzymatic hydrolysis by lipases and by an aerobic gas evolution test in standard activated sludge. The hydrolyzability of these copolymers by three kinds of lipases was affected by their copolymer composition SA/EO, form, andM _n . The copolyesterether (SA/EO=43/57,M _n =48,900) was more easily biodegraded by standard activated sludge compared to the polyester (SA/EO=47/53,M _n =36,300).Presented at the Pacifichem-95, December 17–22, 1995, Honolulu, Hawaii.