Electrolytic aminated carbon materials for the electrocatalytic redox reactions of inorganic and organic compounds

Some kinds of amine groups can be introduced to the glassy carbon surface by the electrode oxidation of the carbon electrode surface in ammonium carbamate solution, and this amine groups modified electrode is named as an aminated glassy carbon electrode. The existences of not only primary amine but also secondary and tertially amines were confirmed by X ray photoelectron spectroscopy. The applications of the aminated carbon material for the electrocatalytic reductions of oxygen, hydrogen peroxide, and organic compounds such as quinones were carried out, and the effects of amination on the formation of electrocatalytic sites for many species were revealed. The electrocatalyzed cyclic voltammograms of metal ions and metal chelate compounds obtained by aminated glassy carbon electrodes are also discussed. Moreover, we intend to describe that the aminated carbon electrode can exhibit the large reduction waves of inorganic oxoacids such as N0₂? or bromide ion. The introduced functional groups containing nitrogen atom can change the distribution of the electron densities of the graphite carbon surface, and this specific electron distribution environment may generate the various electrocatalytic activities.     

Determination of PCBs, PCDDs and PCDFs in insulating oil samples from stored Chinese electrical capacitors by HRGC/HRMS

Homologue and congener profiles of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in commercial PCBs formulations are key information for the source identification of PCBs contamination as well as for the risk assessment caused by potential exposure. The isotope dilution technology in combination with high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) has made the accurate determination of such profiles possible. So far, various commercial PCB formulations except Chinese products have been successfully determined. Two PCBs containing insulating oil samples from stored Chinese electrical capacitors have been determined with the same methodology for comparability. The total concentration PCBs in two oil samples were 790 000 μg g⁻¹ and 720 000 μg g⁻¹, respectively. TriCBs, TetraCBs, and DiCBs were found to be most abundant. Concentration of dioxins contamination in two samples is 650-670 ngTEQ g⁻¹, of which 69-71 ngTEQ g⁻¹ from PCDD/Fs with the predominant congeners of 1,2,7,8-TeCDF; 2,3,7,8-TeCDF; 2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDF. The contributions of DL-PCBs in total TEQ in both samples were more than 85%. The dioxin-like toxicity in insulating oils contained in electrical capacitors could be considered receive attention as an important dioxins source if such wastes are not managed in an environmentally sound manner.     

Estimating monthly total nitrogen concentration in streams by using artificial neural network

Artificial Neural Network (ANN) is a flexible and popular tool for predicting the non-linear behavior in the environmental system. Here, the feed-forward ANN model was used to investigate the relationship among the land use, fertilizer, and hydrometerological conditions in 59 river basins over Japan and then applied to estimate the monthly river total nitrogen concentration (TNC). It was shown by the sensitivity analysis, that precipitation, temperature, river discharge, forest area and urban area have high relationships with TNC. The ANN structure having eight inputs and one hidden layer with seven nodes gives the best estimate of TNC. The 1:1 scatter plots of predicted versus measured TNC were closely aligned and provided coefficients of errors of 0.98 and 0.93 for ANNs calibration and validation, respectively. From the results obtained, the ANN model gave satisfactory predictions of stream TNC and appears to be a useful tool for prediction of TNC in Japanese streams. It indicates that the ANN model was able to provide accurate estimates of nitrogen concentration in streams. Its application to such environmental data will encourage further studies on prediction of stream TNC in ungauged rivers and provide a useful tool for water resource and environment managers to obtain a quick preliminary assessment of TNC variations.     

Application of an Improved Micro-amount of Virion Enrichment Technique (MiVET) for the Detection of Avian Influenza A Virus in Spiked Chicken Meat Samples

Food and Environmental Virology - Highly sensitive detection of pathogens is effective for screening meat during quarantine inspection and export. The “micro-amount of virion enrichment...     

Evaluation of material recycling for plastics: environmental aspects

“Zero emissions” is a concept envisaging the creation of a sustainable society with minimal disposal of resources. In order to realize zero emissions for plastics, it is important to establish a method for quantitatively evaluating candidate recycling processes. In this study, the principle of the substitution factor (SF) is introduced. A quantitative evaluation of the recycling process for plastics was then carried out. The production process for monofilament plastics was examined. The recycling of plastics discarded during the production process could be substituted in small amounts for virgin materials, giving reduced CO₂ emissions. Furthermore, production using recycled material mixed with virgin material was more effective in reducing CO₂ emissions than when recycled materials only were used. Received: November 19, 1999 / Accepted: November 28, 2000     

Metabolism of benzo(a)pyrene in rat by oral administration

Orally administered ³H-benzo(a)pyrene (BP) was concentrated in liver, kidney and lung of rat. Liver contained BP-diols, BP-quinones and 3-hydroxy-BP, and extremely high amounts of BP-quinones and unmetabolized BP were found in lung until after 7 hr of administration. In kidney, BP-quinones and BP-diols were major metabolites, but not BP or 3-hydroxy-BP. Low level of metabolites as conjugates with glucuronate and more polar compounds were also detected in kidney. These results suggested that an orally administered BP was metabolized to BP-diols and 3-hydroxy-BP mainly in liver, to BP-quinones mainly in lung, and to BP-diols and glucuronides or more polar compounds mainly in kidney.     

Fundamental study of the behavior of chlorine during the combustion of single RDF

A fundamental study of the combustion characteristics and the de-HCl behavior of a single refuse-derived fuel (RDF) pellet was carried out to explain the de-HCl phenomena of RDF during fluidized bed combustion and to provide data for the development of high efficiency power generation technology using RDF. In this research, combustion and pyrolysis experiments were carried out in an electrical furnace using a series of model and actual RDF samples. The de-HCl capability of Ca(OH)2 in RDF was evaluated by measuring the emission fraction of HCl in the flue gas and the capture fraction of Cl in the residue. It was found that the capture fraction of Cl components in the residue increased from 0 to nearly 70% when the molar ratio of Ca/Cl was changed from 0 to around 13. Apparently, the capture fraction also decreased with increasing oxygen concentration in the feed gas. The devolatilization process of RDF was confirmed to be a very important part of de-HCl process. The effect of temperature profile of the RDF pellet on the de-HCl process, as it varies with the heating rate of RDF and the oxygen concentration in the vicinity of the sample, is discussed.     

Voltammetric response of ferroceneboronic acid to diol and phenolic compounds as possible pollutants

A voltammetric determination of possible organic pollutants such as diol and phenolic compounds in water was studied using ferroceneboronic acid (FBA) as a redox-active marker. A cyclic voltammogram of FBA exhibited a pair of oxidation and reduction peaks at 230 and 170 mV at pH 7.0, respectively, while another pair of redox peaks was observed in the presence of diol or phenolic compounds tested. The results were rationalized based on the formation of boronate esters of FBA with the added compounds. The changes in the redox peak currents were dependent on the concentration of the additives, suggesting a usefulness of FBA in the electrochemical determination of these compounds in water.     

Depositional records of plutonium and (137)Cs released from Nagasaki atomic bomb in sediment of Nishiyama reservoir at Nagasaki

In a sediment core of Nishiyama reservoir at Nagasaki city, depth profiles of (240)Pu/(239)Pu isotopic ratio, (239+240)Pu and (137)Cs activities were determined. Sediments containing plutonium and (137)Cs, which were deposited immediately after a detonation of Nagasaki atomic bomb, were identified in the core. Observed below the sediments were macroscopic charcoals, providing evidence for initial deposit of the fallout of the Nagasaki atomic bomb. This is the first entire depositional records of plutonium and (137)Cs released from the Nagasaki atomic bomb together with those from atmospheric nuclear tests.     

Metabolism of 3-hydroxybenzo (a) pyrene in rat,isolated hepatocytes and kidney

After intravenous injection of 3-hydroxybenzo (a) pyrene into rat, benzo (a) pyrene-diols were detected in urine, and $\text{in vitro}$ experiment using isolated hepatocytes and sliced kidney also indicated the metabolism of 3-hydroxybenzo (a) pyrene to diol derivatives. THese results suggested the presence of unknown metabolic pathway of benzo (a) pyrene-phenols such as 3-hydroxybenzo (a) pyrene to diol derivatives both $\text{in vivo}$ and $\text{in vitro}$.