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Background: Carcinogens are known to cause swelling of the mammalian cell nucleus. However, the mechanism of the swelling and its toxicological significance have not been fully elucidated. Since nuclear swelling (NS hereafter) has been frequently observed in chromosomal aberration (CA hereafter) tests (in vitro), the relationship between NS and CAs was investigated in this study. Results: In a short-term CA test using the fibroblast CHL cell line, the appearance of NS increased in a dose-dependent manner after exposure to six types of clastogens (mitomycin C, methyl methane sulfonate, 1-methyl-3-nitro-1-nitrosoguanidine, benzo[a]pyrene, cyclophosphamide monohydrate, and 9,10-dimethyl-2-benzanthracene), and a strong correlation was found between NS (%) and CAs (%) at each dosage. Therefore, we hypothesized that clastogens cause NS in cultured mammalian cells, since the mouse lymphoma L5178Y cell line is known to have a similar sensitivity to clastogens. Thus, we measured NS for 14 compounds (clastogens) that are known to induce structural CAs, 4 aneugens, and 12 non-mutagenes. Almost all clastogens caused NS of more than 5 %, which increased in a dose-dependent manner. Among the aneugens, colchicine, and diethylstilbestrol caused the same level of NS % as the clastogens, while carbendazim and trichlorfon caused a similar level of NS % as the clastogens only at higher levels of cytotoxicity. Almost all the non-mutagens caused less than 5 % NS. Conclusions: These results strongly suggest that NS is mainly caused by structural aberrations in the nucleus during interphase of the cell cycle. [ABSTRACT FROM AUTHOR]

Anaerobic bacteria have been used to produce 2,4-dihydroxylamino-nitrotoluene (2,4DHANT), a reductive metabolite of 2,4,6-trinitrotoluene (TNT). Here, an aerobic TNT biodegrader Pseudomonas sp. strain TM15 produced 2,4DHANT as evidenced by the molecular ion with m/z of 199 identified from LC-TOFMS analyses. TNT biodegradation with a high cell concentration (109 cells/ml) led to a significant accumulation of 2,4DHANT in the culture medium, as well as hydroxylamino-dinitrotoluenes (HADNTs), although these products were not accumulated when a low cell concentration was used; also, the accumulation of diamino-nitrotoluene and of an unidentified metabolite were observed in the culture medium with the high cell concentration (1010 cells/ml). 2,4DHANT overproduction was a function of the aeration speed since cultures with low aeration speeds (30 rpm) had a 19-fold higher DHANT productivity than those aerated with high speeds (180 rpm); this indicates that molecular oxygen was related to the formation of 2,4DHANT. The quantification of dissolved oxygen (DO) in the media demonstrated that the productivity of 2,4DHANT was increased at low DO values. Moreover, supplying oxygen to the culture media produced a remarkable decrease of 2,4DHANT accumulation; these results clearly indicate that high 2,4DHANT production was a consequence of the oxygen deficit in the culture medium. This finding is useful for understanding the TNT biodegradation (bioremediation technology) in an anoxic environment. [ABSTRACT FROM AUTHOR]

The development and manufacture of an adsorbent to remove phosphate for the prevention of eutrophication in lakes is very important. The use of aluminium oxide (alumina) as an organic adsorbent to remove phosphate from wastewater has been investigated. The characteristics of this absorption process were investigated to determine the important parameters, such as the pU and the aluminium ion concentration. Moreover, chemical treatment methods to enhance the adsorption capacity of alumina were tested. Dynamic studies and equilibrium adsorption isotherm studies were conducted to determine the adsorption capacity and efficiency. The experimental results indicate that it is necessary to increase the temperature above 500 °C in order to obtain a high-capacity adsorbent, and alumina treated with acid or calcium or magnesium has a larger adsorption capacity for phosphate than untreated adsorbent. Moreover, the adsorption of phosphate was enhanced at a lower pH and a higher aluminium ion concentration, and a simple Freundlich isotherm could express the equilibrium adsorption isotherm, and the intragranular the adsorption capacity and the slope is an indicator of the adsorption intensity. It also shows that the acid treatment method is simple and useful to increase the adsorption capacity. The Freundlich exponent is well below 0.5, which indicates that the adsorption process is favourable. [ABSTRACT FROM AUTHOR]

The adsorption of a fixed bed filled with bone char was investigated in terms of its efficiency and capacity by determining operational conditions for the purpose of further reduction of organic matter and removal of phosphorus using a continuous flow of real secondary effluent. Simultaneous removals of phosphorus and chemical oxygen demand (COD) were sufficiently achieved by this fixed-bed method. Stable performance was maintained even at a linear flow velocity (abbreviated as LV) of 1.5 m h-1. Appropriate backwashing and regeneration were required to operate the system continuously for a long period of time. During the regeneration, the use of treated water including Ca2+ ion was so effective that phosphorus removal efficiency increased from about 50 to 80%, and afterwards maintained over 65%, until inflow water of the volume up to 150 times as large as the volume of bone char had passed through. Even when the inflow water of the volume rose up to 200 times, the phosphorus removal efficiency could be maintained over 50%. During this operation, the adsorptions of phosphorus and COD onto the bone char surface were observed to be over 6.7 and 35 gL-1, respectively. [ABSTRACT FROM AUTHOR]

An experiment of anaerobic filtration using a floating media was carried out in this study. In the present system, a bench-scale column of 50 mm in diameter and of 1500 mm in height and a floating media consisting of S-shaped polystyrene pieces were employed. The purpose of this study was to collect the basic data of anaerobic biological filtration using a floating media. Under the laboratory conditions, it was found that the start-up of an anaerobic biological filter took about half month at 20°C and a lower BOD loading was favorable for this start-up. The BOD removal efficiency over 60% could be achieved at a BOD volumetric loading of the filter bed under 6 kg/m3/d. An effluent BOD concentration became high when the flow rate was high, especially with circulation of treated water, which afforded a large effect on an effluent BOD concentration. As for the mechanism of BOD removal by anaerobic filtration, it was evident that long retention time worked in favor for organic acid generation, and the circulation of treated water promoted decomposition of organic acids. [ABSTRACT FROM AUTHOR]

Interest in the production of lactic acid (LA) is increasing in relation to its applications in the synthesis of biodegradable polymer materials. Before kitchen waste is used as substrates in LA fermentation, it must be stored for some days in the waste collection system. This study examined the effects of pH adjustment including initial pH before the storage in terms of the kind and the amount of added acid on preservation of the waste. The optical purity of LA generated during the storage was also analyzed. It was found that antibacterial activity and suppression ability to D-lactic acid (D-LA) were stronger in the order: acetic acid > L-lactic acid (L-LA) > hydrochloric acid ≈ nitric acid. The optimum condition of waste storage was found to be adjusting initial pH to 3.4 by adding acetic acid. It can be expected that preservation of kitchen waste can be realized by inhibiting the growth of putrefactive bacteria, and higher optical purity of L-LA was obtained by adding weak acid to the waste. [ABSTRACT FROM AUTHOR]

Two kinds of hydroxylamino-dinitrotoluenes, 2-hydroxylamino-4, 6-dinitrotoluene (2HADNT) and 4-hydroxylamino-2, 6-dinitrotoluene (4HADNT), are known to be major metabolites produced from 2,4,6-trinitrotoluene (TNT) by bacteria. The amounts of 2HADNT and 4HADNT in distilled water are found to spontaneously decrease with time, albeit abiotic conditions, and many white precipitates are educed in the processes of this phenomenon; however, how these compounds are converted is unclear. We evinced the mystery of this phenomenon by using thin-layer chromatography (TLC) and laser time-of-flight mass spectrometry (TOFMS). TLC analyses in the spontaneous conversion processes of 2HADNT, 4HADNT, and 2HADNT plus 4HADNT demonstrats that three novel spots emerge on the TLC plate, respectively. These products are individually extracted into acetonitrile by collecting each spot. The purity of these extracts, which have retention times of 14.0, 17.7, and 15.4 min, is approximately 98%, judging from the results of high-performance liquid chromatographic analyses. The spontaneous conversion products of 2HADNT, 4HADNT, and 2HADNT plus 4HADNT are identified as 4,4',6,6'-tetranitro-2,2'-azoxytoluene (2,2'AZT), 2,2',6,6'-tetranitro-4,4'-azoxytoluene (4,4'AZT), and 4,2',6, 6'-tetranitro-2,4'-azoxytoluene (2,4'AZT) by obtaining their mass spectra with laser TOFMS. It is confirmed that most of the spontaneous conversion products are 2,2'AZT, 4,4'AZT, or 2,4'AZT, judging from the results of mass balance in the spontaneous conversion processes of 2HADNT, 4HADNT, and 2HADNT plus 4HADNT.