Return period of enhanced gamma ray dose rates: regional differences observed in Japan

We estimated the return period of an increased gamma ray dose rate (Delta gamma) derived from (222)Rn progeny deposited with precipitation. The approximate probability distribution for Delta gamma followed a Hazen plot, which is an empirical plotting equation, indicating that the distribution of Delta gamma was approximated by a nearly double-exponential. The distribution of Delta gamma was well represented by the Gumbel distribution, and the return period for Delta gamma was estimated theoretically. There was a notable regional difference in the return period between the coast of the Japan Sea and the inland or Pacific coast areas: the return period for a given Delta gamma at monitoring sites on the Sea of Japan coast was 1.5 to 2.5 times shorter than that in the inland or Pacific coast areas. This variation with locality suggests that the rate of wet-deposition of (222)Rn progeny is larger at sites on the Sea of Japan coast than inland or on the Pacific coast areas. The expected return period for the maximum Delta gamma at each site was about 10 years. This estimation of the return period of Delta gamma is a novel approach to the study of environmental science in fields such as radioactivity.     

Quantitative analysis of microbial biomass yield in aerobic bioreactor

We have studied the integrated model of reaction rate equations with thermal energy balance in aerobic bioreactor for food waste decomposition and showed that the integrated model has the capability both of monitoring microbial activity in real time and of analyzing biodegradation kinetics and thermal-hydrodynamic properties. On the other hand, concerning microbial metabolism, it was known that balancing catabolic reactions with anabolic reactions in terms of energy and electron flow provides stoichiometric metabolic reactions and enables the estimation of microbial biomass yield (stoichiometric reaction model). We have studied a method for estimating real-time microbial biomass yield in the bioreactor during food waste decomposition by combining the integrated model with the stoichiometric reaction model. As a result, it was found that the time course of microbial biomass yield in the bioreactor during decomposition can be evaluated using the operational data of the bioreactor (weight of input food waste and bed temperature) by the combined model. The combined model can be applied to manage a food waste decomposition not only for controlling system operation to keep microbial activity stable, but also for producing value–added products such as compost on optimum condition.     

Speciation of the radioactive nuclides in incinerator fly ash of municipal solid waste using sequential extractions

Journal of Material Cycles and Waste Management - The radioactive nuclides in the incinerator fly ashes from municipal solid waste sampled in June 2006 were analyzed with γ-ray spectrometry....     

Preparation and performance of arsenate (V) adsorbents derived from concrete wastes

Solid adsorbent materials, prepared from waste cement powder and concrete sludge were assessed for removal of arsenic in the form of arsenic (As(V)) from water. All the materials exhibited arsenic removal capacity when added to distilled water containing 10–700 mg/L arsenic. The arsenic removal isotherms were expressed by the Langmuir type equations, and the highest removal capacity was observed for the adsorbent prepared from concrete sludge with heat treatment at 105 °C, the maximum removal capacity being 175 mg-As(V)/g. Based on changes in arsenic and calcium ion concentrations, and solution pH, the removal mechanism for arsenic was considered to involve the precipitation of calcium arsenate, Ca₃(AsO₄)₂. The enhanced removal of arsenic for the adsorbent prepared from concrete sludge with heat treatment was thought to reflect ion exchange by ettringite. The prepared adsorbents, derived from waste cement and concrete using simple procedures, may offer a cost effective approach for arsenic removal and clean-up of contaminated waters, especially in developing countries.     

Inception of formation and early morphogenesis of the bacterial light organ of the sea urchin cardinalfish, <Emphasis Type="Italic">Siphamia versicolor</Emphasis>

The cardinalfish Siphamia versicolor (Perciformes: Apogonidae) forms a bioluminescent symbiosis with the marine luminous bacterium Photobacterium mandapamensis, harboring the bacteria in a ventral, disc-shaped light organ and using the bacterial light apparently for counterillumination and attracting prey. Little definitive information has been available on the developmental and microbiological events surrounding the initiation of symbiosis, a critical stage in the life history of the fish, in S. versicolor or any of the many other species of bacterially luminous fish. To identify the stage at which light organ formation begins, to determine the origin of cells forming the light organ, and to characterize its bacterial colonization status during development, early developmental stages of S. versicolor obtained and reared from wild-caught mouth-brooding males were examined with histological and microbiological methods. A light organ primordium was not evident in embryos, post-embryos, or pre-release larvae, whereas the light organ began to form within 1 day of release of full-term pre-flexion larvae from the mouths of male fish. Analysis of post-release larvae revealed that the light organ arises from a proliferation and differentiation of intestinal epithelial cells, and that it quickly develops structural complexity, including the formation of chambers and gaps contiguous with the intestinal epithelium. However, the nascent light organ remained uncolonized by the symbiotic bacteria through several days of post-release development, even in the presence of high numbers of the symbiotic bacteria. These results demonstrate that the inception of light organ formation in S. versicolor occurs independently of its symbiotic bacteria and that receptivity to bacterial colonization apparently requires substantial post-release development of the light organ. Larvae therefore most likely acquire their symbiotic bacteria from seawater, during or shortly after the transition from the pre-flexion to the flexion developmental stage.     

Influence of arsenic stress on synthesis and localization of low-molecular-weight thiols in Pteris vittata

The roles of low-molecular-weight thiols (LMWTs), such as glutathione and phytochelatins, in arsenic (As) tolerance and hyperaccumulation in Pteris vittata an As-hyperaccumulator fern remain to be better understood. This study aimed to thoroughly characterize LMWT synthesis in P. vittata to understand the roles played by LMWTs in As tolerance and hyperaccumulation. LMWT synthesis in P. vittata was induced directly by As, and not by As-mediated oxidative stress. Expression of PvECS2, one of the putative genes of γ-glutamylcysteine synthetase (γECS), increases in P. vittata shoots at 48 h after the onset of As exposure, almost corresponding to the increase in the concentrations of γ-glutamylcysteine and glutathione. Furthermore, localization of As showed similar trends to those of LMWTs in fronds at both whole-frond and cellular levels. This study thus indicates the specific contribution of LMWTs to As tolerance in P. vittata. γECS may be responsible for the As-induced enhancement of LMWT synthesis.     

Direct determination of neonicotinoid insecticides in an analytically challenging crop such as Chinese chives using selective ELISAs

ABSTRACT

Easy-to-use commercial kit-based enzyme-linked immunosorbent assays (ELISAs) have been used to detect neonicotinoid dinotefuran, clothianidin and imidacloprid in Chinese chives, which are considered a troublesome matrix for chromatographic techniques. Based on their high water solubility, water was used as an extractant. Matrix interference could be avoided substantially just diluting sample extracts. Average recoveries of insecticides from spiked samples were 85–113%, with relative standard deviation of <15%. The concentrations of insecticides detected from the spiked samples with the proposed ELISA methods correlated well with those by the reference high-performance liquid chromatography (HPLC) method. The residues analyzed by the ELISA methods were consistently 1.24 times that found by the HPLC method, attributable to loss of analyte during sample clean-up for HPLC analyses. It was revealed that the ELISA methods can be applied easily to pesticide residue analysis in troublesome matrix such as Chinese chives.     

Towards institutional analysis of sustainability science: a quantitative examination of the patterns of research collaboration

This paper examines quantitatively the patterns of collaboration over geographical boundaries in the emerging field of sustainability science by empirically analyzing the bibliometric data of scientific articles. The results indicate that an increasing number of countries are engaged in research on sustainability, with the proportion of articles published through international collaboration rising as well. The number of countries engaged in international collaboration on sustainability research has been increasing, and the diversity of countries engaged in research collaboration beyond national borders is also increasing. The geographical patterns of collaboration on sustainability show that research collaboration tends to be conducted between countries which are geographically located closely, suggesting that communication and information exchange might be limited within the regional clusters. The focused fields of research activities on sustainability are significantly different between countries, as each country has its focused fields of research related to sustainability. The specialization of research activities is also observed in international collaboration. While these patterns of international collaboration within regional clusters focusing on specific fields could be effective in promoting the creation, transmission, and sharing of knowledge on sustainability utilizing the already existing regional networks, they could pose a serious obstacle to collecting, exchanging, and integrating diverse types of knowledge, especially when it is necessary to deal with problems involving large-scale complex interactions with long-term implications, such as climate change. It would be of critical importance to establish inter-regional linkages by devising appropriate institutional arrangements for global research collaboration on sustainability science.