Effects of heavy ions on the germination and survival of Arabidopsis thaliana.

Inhibition of germination and reduction in survival of Arabidopsis thaliana were investigated to study the effects of heavy ions on a multicellular system. Dry seeds of Col and Ler ecotypes were exposed to He, C, Ar and Ne ions with linear energy transfer (LET) in the range of 17-549 keV/micron and to electrons (LET = 0.2 keV/micron).

A new Arabidopsis mutant induced by ion beams affects flavonoid synthesis with spotted pigmentation in testa.

A new stable mutant of Arabidopsis thaliana with a spotted pigment in the seed coat, named anthocyanin spotted testa (ast), was induced by carbon ion irradiation. The spotted pigmentation of ast mutant was observed in immature seeds from 1-2 days after flowering (DAF), at the integument of the ovule, and spread as the seed coat formed. Anthocyanin accumulation was about 6 times higher in ast mutant than in the wild-type at 6 DAF of the immature seeds, but was almost the same in mature dry seeds.

Measurement of reaction rate distributions in a plastic phantom irradiated by 40- and 65-MEV quasi-monoenergetic neutrons.

Reaction rate distributions in a plastic phantom were measured with solid state nuclear track detectors and a fission counter for 40- and 65-MeV quasi-monoenergetic neutrons generated by the 7Li(p,n) reactions with 43- and 68-MeV protons at AVF cyclotron of Japan Atomic Energy Research Institute. Measured distributions were compared with calculated ones.

Recovery of Deinococcus radiodurans from radiation damage was enhanced under microgravity.

Effect of microgravity on recovery of bacterial cells from radiation damage was examined on the IML-2 mission in 1994 using extremely radioresistant bacterium Deinococcus radiodurans. The cells were lyophilized and exposed to 60Co gamma-rays with doses 2 to 12 kGy before the space flight. At the end of the mission, the cells were mixed on board with liquid nutrient medium to allow the cells to start recovery process from the radiation damage.

Sequence analysis of the L-lactate dehydrogenase-encoding gene of Deinococcus radiodurans, a suitable mesophilic counterpart for Thermus.

A gene encoding L-lactate dehydrogenase (LDH; EC 1.1.1.

Changes in cellular proteins of Deinococcus radiodurans following gamma-irradiation.

In order to examine radiation-induced proteins in an extremely radioresistant bacterium, Deinococcus radiodurans R1, changes in cellular proteins after gamma-irradiation were analysed by two-dimensional gel electrophoresis and silver staining. Nine proteins (190, 120, 87,60, 58, 52, 46, 41 and 41 kDa) were increased (or appeared) and more than 13 proteins diminished after gamma-irradiation at 6 kGy. Increase of eight proteins (except for 190-kDa protein) was prevented when the cells were irradiated in the presence of chloramphenicol.

Small angle neutron scattering from lysozyme solutions in unsaturated and supersaturated states (SANS from lysozyme solutions).

Small angle neutron scattering (SANS) method was used to study lysozyme solutions, with particular interest in an understanding of the crystallization process at the initial stage. It is found that (1) in the unsaturated solution, the protein molecules aggregate with a continuous increase in size when NaCl concentration is increased, and (2) in the supersaturated solution, an irreversible change, superimposed on the former process, occurs when the supersaturation is realized. These facts indicate the usefulness of SANS in detecting changes of protein molecules in solution on the nanometer scale.

Development of an atmospheric 222Rn concentration model using a hydrodynamic meteorological model: II. Three-dimensional research-purpose model.

This paper describes a new type of three-dimensional numerical model for 222Rn transport in an atmospheric boundary layer. The model is a combination of a prognostic hydrodynamic meteorological model including a turbulence closure model and an atmospheric diffusion model for 222Rn. The first part provides the second part with the meteorological conditions needed for calculations of the 222Rn transport and diffusion.

Development of an atmospheric 222Rn concentration model using a hydrodynamic meteorological model: I. One-dimensional practical model.

A one-dimensional numerical model for 222Rn transport in an atmospheric boundary layer was developed. The model consists of two parts: a prognostic hydrodynamic model including a turbulence closure model and an atmospheric diffusion model for 222Rn. The first part predicts meteorological conditions to provide the second part with vertical turbulence conditions which affects the vertical motion of 222Rn near the Earth's surface.

Electron energy-loss spectroscopy study of amorphization process of graphite bombarded with hydrogen ions and energetic electrons at low temperatures.

Structural change of graphite bombarded with hydrogen ions as well as energetic electrons is investigated mainly by the EELS (electron energy-loss spectroscopy) technique, with a focus on the formation of diamond-like amorphous (DLA) phase at low temperatures. The chemical effects of hydrogen ions on the amorphization process are examined by comparing the results obtained by hydrogen-ion bombardment with those obtained by electron bombardment. The critical temperatures for the formation of DLA phase during hydrogen-ion and electron bombardments are determined.

Characteristics of the chemical forms of 11C, 13N, and 15O induced in air by the operation of a 100 MeV electron linear accelerator.

To characterize airborne radioactivity induced by the operation of high-energy accelerators, the fractions of aerosol and gaseous components, and the chemical forms of 11C, 13N, and 15O produced in the air of a target room of a 100 MeV electron linear accelerator were studied. Measurements of radioactivity using a particulate air sampling filter and a gas flow-through ionization chamber showed that more than 98% of 11C, 13N, and 15O were present as gaseous forms. Their chemical forms, detected by means of radio-gas chromatography, were 11C as CO2; 13N as N2 and NO; and 15O as O2 and NO.

Plasmids in several strains of Deinococcus radiodurans.

Deinococcus radiodurans is known as a radioresistant bacterium. For the construction of the shuttle vector, plasmids of this bacterium were isolated and investigated. At least two new plasmids in the cells of D.

A new model of shouldered survival curves.

Recently, the linear-quadratic equation has been used to construct the dose-response relationships of ionizing radiation. The radiobiological theory on which this relationship is based indicates that at low doses, the risk of a biological lesion being formed should depend linearly on dose if a single event is required or quadratically on dose if two events are required. The same approach has also been used to construct the shouldered survival curves, which indicate a lower response of cell killing at low doses of low linear energy transfer (LET) radiation than at high doses because of repair.

Biodegradable poly(DL-lactic acid) formulations in a calcitonin delivery system.

A synthetic analogue of eel calcitonin, [Asu1, 7]-ECT, was incorporated into biodegradable poly(DL-lactic acids) with number-average molecular weights (Mn) of 1400-4400 by the melt-pressing technique. The in vitro release of drug from a parabolically degradable poly(DL-lactic acid) with Mn = 1400 showed an initial burst release and completed the release in 3 d from the start of the test. The drug release from a Mn = 4400 polymer with an S-type degradation pattern was kept at 14 +/- 5 units/d for an experimental period of 24 d.

Assessment of the chemical form of gaseous 35S species produced during the production of H3(32)PO4.

The chemical form of gaseous 35S species produced during the production of H3(32)PO4 was characterized in order to reduce 35S discharge by understanding its production mechanism and chemical reactivity. An air sample was evacuated from the cell in which the H3(32)PO4 production was being carried out and collected in a sample gas reservoir. Gaseous sulfur species contained in the sample were condensed in a cold trap maintained at -180 degrees C and analyzed by means of gas chromatography using a flame photometric detector.

Recognition of microbial cells by the surface of polymers with oxyethylene units.

The recognition of microbial cells by the surface of polymers with oxyethylene units was investigated using the organism Trichoderma reesei, in which the surface was modified by the radiation polymerization method. The cells were recognized by their adhesion to the surface of the polymer giving a bioaffinity similar to cell fusion. The adhesion was affected by the molecular structure of the surface relating to the length of the oxyethylene unit, and enzyme productivity from the adhered cell walls was affected by the property of the polymer.

[Schizophrenia and reverse-Stroop interference in the group version of the Stroop and reverse-Stroop test].

Previous studies showed that attentional task performance of schizophrenics was significantly inferior to that of normals. The classical Stroop Color-Word Interference Test is an example of such attentional tasks and performance on the "reverse" Stroop task is reported to discriminate schizophrenics from normals better than the regular Stroop task. These results suggest that schizophrenics are more susceptible to "reverse" Stroop interference in reading incongruent word-color combinations than normals.

Distribution of pathogenic vibrios and other bacteria in imported frozen shrimps and their decontamination by gamma-irradiation.

The distribution of pathogenic vibrios and other bacteria in eight samples of imported frozen shrimps and the effect of irradiation on these bacteria were investigated. Total aerobic bacteria were at 2×10(4) to 4×10(6)/g. Coliforms consisted mainly ofEnterobacter.

Development of a chemical form discrimination system for 14C species in gaseous waste.

A new system was developed for discriminating the chemical form of 14C species in gaseous waste from nuclear facilities. The system consists of an air sample reservoir, a concentration apparatus, a radio-gas chromatograph, and microcomputers. An air sample, which is part of the gaseous effluent released from a stack of a facility, is automatically collected in the tank by trigger signals of stack monitors.

Impact of supersonic versus propeller wind data on dispersion estimates for nuclear plants.

Statistical analyses and comparisons of the wind data obtained by the propeller and supersonic anemometers at the Japan Atomic Energy Research Institute (JAERI) were performed. For wind speeds less than 1 ms-1, the propeller readings are inaccurate and are generally 0.5 ms-1 less than the supersonic readings.

In vivo characteristics of high molecular weight copoly(L-lactide/glycolide) with S-type degradation pattern for application in drug delivery systems.

Amorphous copoly(L-lactide)/glycolide, 70/30 mol%) with weight average molecular weights of 16,900-41,300 were synthesized by ring-opening polymerization in the presence of catalysts using a molecular weight moderator lauryl alcohol. The in vivo degradation profiles of the copolyesters, which were evaluated by implanting them subcutaneously in the back of rats, showed a typical S-type degradation pattern. A luteinizing hormone-releasing hormone agonist (LH-RH agonist), des-Gly10-[Leu6]-LH-RH ethylamide monoacetate, was incorporated into the small cylinders of copoly (L-lactide/glycolide) with a weight average molecular weight of 24,000.

Thermo-responsive hydrogels based on acryloyl-L-proline methyl ester and their use as long-acting testosterone delivery systems.

New thermo-responsive hydrogels were synthesized by copolymerizing acryloyl-L-proline methyl ester (A-ProOMe) with minor amounts of 2-hydroxypropyl methacrylate (HPMA) or polyethylene glycol 600 dimethacrylate (14G), using gamma-rays from a 60Co source. In water, extensive swelling of the hydrogels occurred at 10 degrees C, but there was marked deswelling as the temperature was raised to 37 degrees C. The poly(A-ProOMe-co-HPMA) hydrogel was characterized by an initial rapid shrinkage at the surface in the deswollen state; this shrinkage arose because of the formation of a rigid membrane barrier devoid of micropores.

[Efficiencies of contamination source for flooring and some materials used in unencapsulated radioactivity handling facilities].

The efficiencies of contamination source, defined in ISO Report 7506-1, were experimentally determined for such materials as flooring, polyethylene, smear-tested filter paper and stainless steel plate. 5 nuclides of 147Pm, 60Co, 137Cs, 204Tl and 90Sr-Y were used to study beta-ray energy dependence of the efficiency, and 241Am as alpha-ray emitter. The charge-up effect in the measurement by a window-less 2 pi-proportional counter was evaluated to obtain reliable surface emission rate.