Environmental protection: researches in National Institute of Radiological Sciences

Some studies for radiological protection of the environment have been made at the National Institute of Radiological Sciences (NIRS). Transfer of radionuclides and related elements has been investigated for dose estimation of non-human biota. A parameter database and radionuclide transfer models have been also developed for the Japanese environments. Dose (rate)-effect relationships for survival, growth and reproduction have been investigated in conifers, Arabidopsis, fungi, earthworms, springtails, algae, duckweeds, daphnia and medaka. Also genome-wide gene expression analysis has been carried out by high coverage expression profiling (HiCEP). Effects on aquatic microbial communities have been studied in experimental ecosystem models, i.e., microcosms. Some effects were detected at a dose rate of 1 Gy day(-1) and were likely to arise from interspecies interactions. The results obtained at NIRS have been used in development of frameworks for environmental protection by some international bodies, and will contribute to environmental protection in Japan and other Asian countries.     

Theoretical Estimation of Changes in Plane Elastic Waves due to Cylindrical Inclusions

Changes in amplitude and phase shifts in plane elastic waves were theoretically estimated when they propagated through an elastic body containing cylindrical inclusions. Based on the integral equation suggested by Lavrov et al., these changes were calculated in the case when only one cylindrical inclusion was located in the body and the propagating waves have a single frequency. These calculations were expanded to more practical case when multiple cylindrical inclusions aligned in the body and the waves have some frequency band. The changes in amplitude and phase shifts calculated were associated to the changes in apparent sonic velocity and attenuation coefficient due to a structural change in the material. This theoretical approach contributes to a quantitative damage evaluation based upon structural changes in various materials by measuring the acoustical parameters such as apparent sonic velocity and attenuation coefficient.     

Photocatalyzed N-demethylation and degradation of methylene blue in titania dispersions exposed to concentrated sunlight

S imulated wastewaters that con tain methylene blue (MB) were bleached in a photocatalytic aqueous TiO₂ dispersion illuminated by concentrated sunlight using a parabolic round concentrator reactor (PRCR). The kinetic analysis was carried out well when the temporal concentration variation was a function of the concentrated light energy irradiated. The p hotocatalyzed N-demethylation of MB takes place concurrently with photocatalytic decomposition of MB by pseudo- first-order kinetics. The dependence of the photo- decomposition kinetics on the initial concentration of MB is consistent with the Langmuir– Hinshelwood model. Elimination of TOC (total organic carbon) also occurs by pseudo- first-order kinetics prior to full bleaching of the aqueous TiO₂ dispersion, after which the TOC level decreases only slightly. Also, compared with the open to air, the photodegradation of MB is not influenced by molecular oxygen bubbl ing continuously through the reactant suspensions during illumination . TiO₂ loadings and flow rates markedly a ffect the degradation o f MB. Under concentrated sunlight, t he relative photonic efficiency of MB photodegradation i s ζ_rel=0.49 (relative to phenol) . T he efficiency ζ_rel for the degradation of MB is independent of photoreactor geometry (cylindrical bottle reactor versus round-bot tomed flask), of light sources (solar light concentrator versus a Hg lamp) and of the operating mode used (flow versus batch operation).     

Bubble behavior in vertical tube banks installed in a fluidized bed

Fluidized bed combustion is one of the advantageous technologies for coal and/or incineration firing especially with respect to the environmental protection of emissions, such as NO_x/SO_x. Bed material movement in such a fluidized bed has a prime importance in the heat transfer process. Thus, quantitative measurement of the bed material movement and the void fraction are indispensable for better understanding of the fluidized bed. In this investigation, neutron radiography is applied to visualize the bed material movement in a simulated fluidized bed heat exchanger installed with vertical tubes. Bubble behavior and void fraction profile are obtained by the image processing technique. Bubble movement is highly restrained by these vertical tubes, so that the bubbles rise up along the tube. The bubble diameter is well correlated by the modified Mori and Wen's correlation taking into account the pitch of the tube arrangement. The bubble rise velocity and void fraction are well correlated by applying the drift‐flux model. © 2003 Wiley Periodicals, Inc. Heat Trans Asian Res, 32(8): 727–739, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.10127     

Photocatalyzed mineralization of a trimethylated phenol in oxygenated aqueous titania. An alternative to microbial degradation

The most methylated phenolic substrate in coal tar creosote, 2,3,5-trimethylphenol (TMP), was mineralized photocatalytically to CO₂ and water at pH 3 in illuminated air-equilibrated titania dispersions. Trimethylhydroquinone and trimethylbenzoquinone were the two major aromatic intermediates; trace amounts of trimethylcatechol also formed. Complete mineralization was achieved in oxygenated solutions in ～1 h; conversion of TMP was over in less than ～25 min in aerated solutions and in less than 12 min in oxygenated solutions.     

Detection of potato virus Y P1 protein in infected cells and analysis of its cleavage site

We report a patient with congenital homozygous factor V deficiency in whom a large pseudotumour in the right upper leg was successfully surgically excised under continuous substitution with fresh-frozen plasma.     

Progressive patterns of degenerative arthritis in scaphoid nonunion demonstrated by three-dimensional computed tomography

PURPOSE: To investigate the kinetics of chromosomal instability induced in clones of Chinese hamster cells following X-irradiation. MATERIALS AND METHODS: X-irradiated clones of GM10115, human-hamster hybrid cells containing a single human chromosome 4 (HC4), have been previously established. These clones were defined as unstable if they contained > or = three subpopulations of cells with unique rearrangements of HC4 as detected by FISH. Stable and unstable clones were analysed by FISH and Giemsa staining at various times post-irradiation. RESULTS: While most of the stable clones continued to show chromosomal stability of HC4 over time, one became marginally unstable at approximately 45 population doublings post-irradiation. Clones exhibiting chromosomal instability had one of several fates. Many of the unstable clones were showed similar levels of instability over time. However, one unstable clone became stable with time in culture, while another became even more unstable over time. Cytogenetic analyses of all clones after Giemsa staining indicated that in some clones the hamster chromosomes were rearranged independent of HC4, demonstrating increased frequencies of chromatid breaks and dicentric chromosomes. The majority of the unstable clones also had higher yields of chromatid gaps. CONCLUSIONS: These data demonstrate the dynamic nature of chromosomal instability as measured by two different cytogenetic assays.     

Effect of a new rifamycin derivative, rifalazil, on liver microsomal enzyme induction in rat and dog

1. The effect of a new rifamycin derivative, rifalazil (KRM-1648), on liver microsomal enzyme induction was studied in rat and dog with repeated oral administration of the compound. Relative liver weight, cytochrome b5 and P450 contents, enzyme activities of NADPH-cytochrome c reductase, aniline hydroxylase, p-nitroanisole O-demethylase, aminopyrine N-demethylase, and erythromycin N-demethylase were measured. 2. In rat, rifalazil treatment at 300 mg/kg/day for 10 days increased cytochrome b5 content but it did not affect liver weight, P450 content or enzyme activities. In contrast, rifampicin and rifabutin increased relative liver weights, cytochrome contents and enzyme activities under similar conditions. 3. In dog, rifalazil did not affect any parameters at 30 or 300 mg/kg/day for 13 weeks. 4. These findings indicate that rifalazil is not an enzyme inducer in rat and dog. This property differs from other rifamycin derivatives such as rifampicin and rifabutin.     

Cellular array processor CAP and applications

The general-purpose, highly parallel, cellular array processor (CAP) we developed features multiple-instruction stream, multiple-data stream (MIMD) processing and image display. Processor elements can number in several hundreds. The present system uses 256 processors. Each processor element consists of a general-purpose microprocessor, memory, and a special VLSI chip that performs parallel-processing-specific functions such as processor communication and synchronization. The VLSI has two 2M byte/s independent common bus interfaces for data broadcating and six 15M bit/s serial communication ports for local data communication. The chip also can process image data in real time for multiple processors. Use of the communication interfaces enables a variety of processor networks to be configured. One CAP application has been computer graphics, in which ray tracing is used to generate quality images.     

Inter-isoformal regulation of nitric oxide synthase through heteromeric dimerization

A 130-kD protein that coimmunoprecipitates with the tight junction protein ZO-1 was bulk purified from Madin-Darby canine kidney (MDCK) cells and subjected to partial endopeptidase digestion and amino acid sequencing. A resulting 19-amino acid sequence provided the basis for screening canine cDNA libraries. Five overlapping clones contained a single open reading frame of 2,694 bp coding for a protein of 898 amino acids with a predicted molecular mass of 98,414 daltons. Sequence analysis showed that this protein contains three PSD-95/SAP90, discs-large, ZO-1 (PDZ) domains, a src homology (SH3) domain, and a region similar to guanylate kinase, making it homologous to ZO-1, ZO-2, the discs large tumor suppressor gene product of Drosophila, and other members of the MAGUK family of proteins. Like ZO-1 and ZO-2, the novel protein contains a COOH-terminal acidic domain and a basic region between the first and second PDZ domains. Unlike ZO-1 and ZO-2, this protein displays a proline-rich region between PDZ2 and PDZ3 and apparently contains no alternatively spliced domain. MDCK cells stably transfected with an epitope-tagged construct expressed the exogenous polypeptide at an apparent molecular mass of approximately 130 kD. Moreover, this protein colocalized with ZO-1 at tight junctions by immunofluorescence and immunoelectron microscopy. In vitro affinity analyses demonstrated that recombinant 130-kD protein directly interacts with ZO-1 and the cytoplasmic domain of occludin, but not with ZO-2. We propose that this protein be named ZO-3.