Yoshio Akimoto

Design and evaluation of radioactive acetylcholine analogs for mapping brain acetylcholinesterase (AchE) in vivo

For mapping brain acetylcholinesterase (AchE) in vivo, seven radioactive acetylcholine analogs, N-[14C]methylpiperidyl-3- and 4-acetates, propionates, isobutyrates, and 3-butyrate were newly synthesized and evaluated in mice. The esters readily entered the brain and were hydrolyzed into the hydrophilic metabolite, which was trapped. In brain homogenates, the esters showed a wide range of enzymatic reactivity (about 40-fold), and high specificity for AchE (more than 82%) except the butyrate. Intra-brain distribution of the esters reflected a pattern of AchE activity.

Oxygenated polycyclic aromatic hydrocarbons from MSW incinerator fly ash

Abstract The qualitative analysis of moderately polar organic compounds in fly ash from a municipal solid waste incinerator (MSWI) was carried out by GC/MS. NINETY SEVEN oxygenated polycyclic aromatic hydrocarbons (oxy-PAHs), including known toxic substances were detected. They were classified into five groups by their structures. Aldehydes and most ketones detected had already been reported as oxy-PAHs in fly ash; however, most quinones and pyrones and all dicarboxylic acid anhydrides were found for the first time.

Control of PCDD and PCDF formation in fluidized bed incinerators

Abstract The object of this study was to know how the formation of PCDDs and PCDFs in fluidized bed incinerators could be controlled. Therefore the relationship between levels of hydrogen chloride in flue gas in municipal waste combustion and PCDDs and PCDFs formed thereby was investigated. In order to decrease the concentration of formed hydrogen chloride in the gas, Dolomite was supplied into the furnace. When the supplied amounts of Dolomite were increased, the concentration of hydrogen chloride in the gas at the outlet of the electrostatic precipitator (EP) were clearly decreased. PCDDs and PCDFs in the boiler and the EP ash samples and in the gas samples were found at lower levels in proportion to the decrease of levels of hydrogen chloride in the gas.

Comparative study on formations of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans and related compounds in a fluidized bed solid waste incinerator using long term used sand and fresh sand

In a fluidized bed incinerator (FBI), municipal solid waste incinerated with the help of sand which had been repeatedly used for two months (worn-out sand) yielded one-order higher concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated benzenes (PCBzs) and polychlorinated phenols (PCPs) in comparison with that incinerated on unused (fresh) sand. As metal concentrations in sand increased after each cycle of incineration, the worn-out sand used contained one to two-order higher amount of metals than the sand used for the first time. Taken together, these findings might imply that the accumulation of metals in worn-out sand is responsible for the increase in the amounts of polychlorinated compounds.

Relationship between the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans and the control of combustion, hydrogen chloride level in flue gas and gas temperature in a municipal waste incinerator

Abstract The control of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) formation was investigated in a municipal waste incinerator equipped with the electrostatic precipitator (EP). The simultaneous control of combustion, hydrogen chloride (HCl) concentration level in the flue gas and the gas temperature proved very effective in the control of PCDDs/Fs formation, reducing the concentration levels of PCDDs/Fs in the flue gas at the EP outlet to 0.2 ng/Nm3 as 2,3,7,8-tetrachlorodibenzo-p-dioxin when evaluated by the international toxicity equivalent factors.

Leaching of polychlorinated dibenzo-p-dioxins and dibenzofurans in fly ash from municipal solid waste incinerators to a water system

In order to predict how much polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) are leached from fly ash by rain water when fly ash is disposed, leaching of PCDDs/Fs from a fly ash obtained from a municipal solid waste incinerator (MSWI) was investigated by packing the ash in a column and eluting with water. In the beginning of the elution, PCDDs/Fs associated with water-soluble particulates in the ash were eluted, whereas in the latter half, those associated with water slightly soluble particles were eluted, judging from the comparison of PCDDs/Fs in eluate fractions with those transferred to solutions from the original ash by stepwise batch methods with water and 2N hydrochloric acid.The amounts of PCDDs/Fs eluted from the ash column were 2.9% and 1.7% of those extracted from the original ash, respectively, while large amounts of PCDDs/Fs were contained in the fly ash in the column after the elution, suggesting that PCDDs/Fs in water-insoluble particulates of the ash would not be eluted by water.

Comparative study on formations of polychlorinated dibenzo-p-dioxin, polychlorinated dibenzofuran and related compounds by pyrolysis of some precursors on unused sand for fluidized bed incinerator and long term used sand

Abstract The effect of wearing of sand in the furnaces of fluidized bed incinerators (FBIs) on the formation of polychlorinated dibenzo-p-dioxin (PCDD), polychlorinated dibenzofuran (PCDF) and their related compounds from polychlorinated biphenyl (PCB) and 1,2,3-trichlorobenzene (1,2,3-T3CBz) was studied experimentally using a pyrolysis apparatus consisting of an injection unit; a stainless steel tube, in which packed was either unused sand (virgin sand) or used for two months in FBI (worn-out sand), heated to 650°C by an electric furnace; and a sampling unit. Furthermore, polychlorinated diphenyl ether (PCDE) was pyrolyzed on worn-out sand in order to compare the formation mechanisms of PCDD and PCDF with those from PCBs. Besides the generation of PCDD and PCDF, the hydroxylation of the starting compounds occurred. PCB was detected in the pyrolyzed samples of 1,2,3-T3CBz on both types of sand. In all cases, PCDF was in much higher yield than PCDD and pyrolysis on worn-out sand was more favorable for the formation of PCDD, PCDF and their relatives than pyrolysis on virgin sand. There was marked difference in metal concentrations between virgin and worn-out sand, implicating that the increased metal concentrations in sand would promote the formation of PCDD, PCDF and their related compounds in FBIs.

Aromatic carboxylic acids generated from MSW incinerator fly ash

Abstract The total of 128 aromatic monocarboxylic acids (ACAs) including 36 mono-to tetrachlorinated compounds were qualitatively detected in fly ash from municipal solid waste incinerators (MSWIs) by GC/MS. They are structually classified into five groups; polycyclic aromatic hydrocarbons (PAHs), biphenyls, oxa-PAHs, oxo-PAHs, and hydroxy-PAHs. The demonstration of dicarboxylic acids was unsuccessful. ACAs might afford oxygenated PAHs by intramolecular dehydration and/or other reactions. The detection of polychlorinated benzoic acids and biphenyl carboxylic acids, possibly candidates for the precursors of polychlorinated dibenzo- p -dioxins and dibenzofurans, might imply the existence of novel pathways.

Effective Sampling System for Polychlorinated Dibenzo-p-dioxins and Polychlorinated Dibenzofurans in Flue Gas from Municipal Solid Incinerators.

Dodecyl sulfuric acid-binding DEAE-Sephadex (DS-Sephadex) was developed as the adsorbent to trap polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/F) in flue gas. Using a DS-Sephadex column, an improved sampling system for PCDD/F in flue gas from municipal solid waste incinerators (MSWIs) was investigated. The system was composed of a probe for drawing flue gas, a filter for collecting dust, impingers for removing acidic substances in flue gas which would decrease trapping activity of the DS-Sephadex, a DS-Sephadex column for trapping PCDD/F, and a vacuum system. As several fundamental experiments for the application of DS-Sephadex to the adsorbent column, uptake efficiency of PCDD/F by the DS-Sephadex column, effective elution of PCDD/F from the column, retention of surrogate PCDD/F on the column during sampling flue gas from a MSWI, distribution of PCDD/F in the column after the sampling, etc. were investigated in detail. In the sampling of flue gas, PCDD/F in solid and gaseous forms were effectively trapped onto the DS-Sephadex column without breaking through during sampling. Thus, a simple and efficient system for sampling PCDD/F in flue gas was developed without requirement of a backup system

Formations of polychlorinated dibenzo-p-dioxins (PCDD) and dibenzofurans (PCDF) in rotary combustor

Abstract PCDD and PCDF in flue gas and ash were determined when municipal solid waste was burnt in a rotary combustor (RC) and PCDD and PCDF were measured by GC/MS/SIM. PCDD and PCDF in the boiler outlet gas showed higher concentration levels than did those in the boiler inlet gas at the combustion of several amounts of refuse. PCDD and PCDF in the ashes and the gases showed low concentrations by the operation of the RC even over its capacity. The concentrations of PCDD and PCDF in the EP outlet gas and EP ash of the RC were observed lower than in those found in other incinerators in Japan. In the RC, the combustion of refuse was operated with good control of the carbon monoxide level. The formation of PCDD and PCDF in flue gas can be controlled by control of the carbon monoxide and with high temperaure conbustion in the RC.