Time-series variations in 129I concentrations and 129I/137Cs ratios in suspended particulate matter collected in eastern Japan immediately after the 2011 nuclear accident in Fukushima, Japan

We have determined the hourly atmospheric concentrations of ¹²⁹I in aerosols dispersed into the atmosphere by the nuclear accident at the Fukushima Daiichi Nuclear Power Plant (FD1NPP) on March 11, 2011. Data were obtained by measuring the quantity of ¹²⁹I in suspended particulate matter (SPM) collected on filter tapes at 41 SPM monitoring stations in Fukushima and other prefectures in eastern Japan, including the metropolitan area of Tokyo and the surrounding area. After scrutiny, 500 out of 920 hourly SPM samples were determined to be reliable (i.e., devoid of cross-contamination), and these were subjected to further analysis and discussion. Based on the data from these samples, especially data from the four SPM sampling sites located close to the FD1NPP (Futaba, Naraha, Haramachi and Nihonmatsu), the time-series variations in the atmospheric concentration of ¹²⁹I and the activity ratio of ¹²⁹I/¹³⁷Cs were reconstructed by using ¹³⁷Cs concentration data in the literature. ¹²⁹I and ¹³⁷Cs were observed to be continuously and sometimes explosively dispersed into the atmosphere in aerosols transported by radioactive plumes from the FD1NPP. The highest activity concentrations of ¹²⁹I and ¹³⁷Cs were observed in the SPM sample at the Futaba SPM station (3.2 km west-northwest of the FD1NPP) at 14:00-15:00 on March 12 after the venting of Unit 1. Systematically high ¹²⁹I/¹³⁷Cs activity ratios were observed at the Futaba and Haramachi stations from March 12 to 14, suggesting that radioactive masses released from the FD1NPP during the first few days after the nuclear accident were relatively enriched in radioiodine. High activity ratios of ¹²⁹I/¹³⁷Cs were also measured starting on March 21 at Naraha (17.5 km south of FD1NPP) and from March 22-23 in the metropolitan area which must have been caused by a different type of emission event(s) on those days at the FD1NPP, as previously reported. The ¹²⁹I data from this study are highly effective in the validation and elaboration of the modelling of the atmospheric dispersion of radioiodine. They further contribute to assessing the internal exposure due to inhalation of ¹³¹I estimated by means of such elaborate atmospheric diffusion models.

Reassessment of early 131I inhalation doses by the Fukushima nuclear accident based on atmospheric 137Cs and 131I/137Cs observation data and multi-ensemble of atmospheric transport and deposition models

The Fukushima Dai-ichi Nuclear Power Plant accidents following the March 11, 2011 Tohoku earthquake, and subsequent tsunami released radioactive materials into the atmosphere and caused significant public health concerns, particularly thyroid cancers in children. However, the lack of measurement data for atmospheric concentrations of ¹³¹I has caused persistent and widespread uncertainty. This study estimated the maximum potential thyroid doses of inhaled ¹³¹I in the early post-accident phase between March 12 and 23, 2011 by using the hourly measured data of the ¹³⁷Cs concentrations at 101 suspended particulate matter (SPM) monitoring sites, a new multi-model ensemble (MME) method of simulating ¹³⁷Cs concentrations using two Atmospheric Transport and Deposition Models (ATDMs), the ¹³¹I/¹³⁷Cs ratio obtained from measurement data analysis, and the internal exposure model. Based on the measurements, the maximum potential thyroid doses were estimated at 3.1-160 mSv at 5 sites in the Fukushima-Hamadori area for 1-year-old children assumed to remain outdoors, whereas they were less than 4.3 mSv at the other sites in the base case of the ¹³¹I/¹³⁷Cs ratio. The spatial distribution of the maximum potential of early inhalation doses was estimated by using the MME and measurements. The inhalation thyroid doses in the evacuation scenarios were compared to the estimates reported by previous studies. The results of the present study were almost congruent with the outcomes of previous investigations except for thyroid doses contributed by highly contaminated plumes on March 12 and 15. The sensitivity analysis for the ¹³¹I/¹³⁷Cs ratio indicated that these plumes carried the potential to significantly increase the thyroid doses of residents.

A new approach for reconstructing the 131I-spreading due to the 2011 Fukushima nuclear accident by means of measuring 129I in airborne particulate matter

To retrieve the diffusion trajectory of the ¹³¹I dispersed in the environment by the nuclear power plant accident in Fukushima in 2011, airborne particulate matter (APM) samples collected in the Tokyo metropolitan area were analyzed for their ¹²⁹I contents by means of accelerator mass spectrometry. In evaluating blank levels of chemicals and filters used for collecting APM, we established the analytical procedure for determining the ¹²⁹I activity of as low as 10^-8 Bq for a small piece of filter samples (about 0.1 cm²). Coupled with ¹³¹I data determined just after the accident, activity ratios of ¹²⁹I/¹³¹I were obtained with a mean value of 2.29 × 10^-8 (±28% of a standard deviation). This value is systematically smaller than a mean value of soil samples by 16-24% and the inventory data by 27%, suggesting that ¹²⁹I was partly lost from APM. As ¹²⁹I can be a proxy of ¹³¹I for APM, it is possible to trace how ¹³¹I in the particulate phase spread in eastern Japan and, furthermore, evaluate the internal radiation exposure due to ¹³¹I by inhalation of ¹³¹I-containing airborne particulates.

Inverse modeling of the 137Cs source term of the Fukushima Dai-ichi Nuclear Power Plant accident constrained by a deposition map monitored by aircraft

The amount of ¹³⁷Cs released by the Fukushima Dai-ichi Nuclear Power Plant accident of 11 March 2011 was inversely estimated by integrating an atmospheric dispersion model, an a priori source term, and map of deposition recorded by aircraft. An a posteriori source term refined finer (hourly) variations comparing with the a priori term, and estimated ¹³⁷Cs released 11 March to 2 April to be 8.12 PBq. Although time series of the a posteriori source term was generally similar to those of the a priori source term, notable modifications were found in the periods when the a posteriori source term was well-constrained by the observations. Spatial pattern of ¹³⁷Cs deposition with the a posteriori source term showed better agreement with the ¹³⁷Cs deposition monitored by aircraft. The a posteriori source term increased ¹³⁷Cs deposition in the Naka-dori region (the central part of Fukushima Prefecture) by 32.9%, and considerably improved the underestimated a priori ¹³⁷Cs deposition. Observed values of deposition measured at 16 stations and surface atmospheric concentrations collected on a filter tape of suspended particulate matter were used for validation of the a posteriori results. A great improvement was found in surface atmospheric concentration on 15 March; the a posteriori source term reduced root mean square error, normalized mean error, and normalized mean bias by 13.4, 22.3, and 92.0% for the hourly values, respectively. However, limited improvements were observed in some periods and areas due to the difficulty in simulating accurate wind fields and the lack of the observational constraints.

First retrieval of hourly atmospheric radionuclides just after the Fukushima accident by analyzing filter-tapes of operational air pollution monitoring stations

No observed data have been found in the Fukushima Prefecture (FP) for the time-series of atmospheric radionuclides concentrations just after the Fukushima Daiichi Nuclear Power Plant (FD1NPP) accident. Accordingly, current estimates of internal radiation doses from inhalation, and atmospheric radionuclide concentrations by atmospheric transport models are highly uncertain. Here, we present a new method for retrieving the hourly atmospheric ¹³⁷Cs concentrations by measuring the radioactivity of suspended particulate matter (SPM) collected on filter tapes in SPM monitors which were operated even after the accident. This new dataset focused on the period of March 12–23, 2011 just after the accident, when massive radioactive materials were released from the FD1NPP to the atmosphere. Overall, 40 sites of the more than 400 sites in the air quality monitoring stations in eastern Japan were studied. For the first time, we show the spatio-temporal variation of atmospheric ¹³⁷Cs concentrations in the FP and the Tokyo Metropolitan Area (TMA) located more than 170 km southwest of the FD1NPP. The comprehensive dataset revealed how the polluted air masses were transported to the FP and TMA, and can be used to re-evaluate internal exposure, time-series radionuclides release rates, and atmospheric transport models.

Quality assessment of INAA data for small-sized environmental reference samples

Instrumental neutron activation analysis (INAA) was applied for the accurate and precise determination of minor and trace elements in small-sized aliquants (1 to 2 mg) of two certified reference materials (CRM), NIES No. 8 and NIST 1632c. Four laboratories used either comparative- or k0-INAA, or both, and repeated the analysis more than ten times for each CRM. Based on z-scores and zeta scores of analytical data, QA/QC in analyzing such small scale of the two reference samples was assessed, revealing that there was a clear difference in the analytical ability among participating laboratories. It was concluded that the two CRM samples on the mg scale can be used as reference samples in INAA of a similarly small-scaled sample, at least for the 16-18 elements examined.

Non-destructive elemental analysis of large meteorite samples by prompt gamma-ray neutron activation analysis with the internal mono-standard method

Prompt gamma-ray neutron activation analysis (PGNAA) using the internal mono-standard method was tested for its applicability to analyzing large solid samples including irregularly shaped meteorite samples. For evaluating the accuracy and precision of the method, large quantities of the Geological Survey of Japan standardized rock powders (JB-1a, JG-1a, and JP-1) were analyzed and 12 elements (B, Na, Mg, Al, Cl, K, Ca, Ti, Mn, Fe, Sm, and Gd) were determined by using Si as an internal standard element. Analytical results were mostly in agreement with literature values within 10 %. The precision of the method was also shown to be within 10 % (1σ) for most of these elements. The analytical procedure was then applied to four stony meteorites (Allende, Kimble County, Leedey, Lake Labyrinth) and four iron meteorites (Canyon Diablo, Toluca (Mexico), Toluca (Xiquipilco), Squaw Creek) consisting of large chunks or single slabs. For stony meteorites, major elements (Mg, Al, Si, S, Ca, and Ni), minor elements (Na and Mn) and trace element (B, Cl, K, Ti, Co, and Sm) were determined with adequate accuracy. For iron meteorites, results for the Co and Ni mass fractions determined are all consistent with corresponding literature values. After the analysis, it was confirmed that the residual radioactivity remaining in the sample after PGNAA was very low and decreased down to the background level. This study shows that PGNAA with the internal mono-standard method is highly practical for determining the elemental composition of large, irregularly shaped solid samples including meteorites.

Photofission of209Bi at intermediate energies

The reaction yields of 63 radionuclides with the mass numberA= 56 − 135 produced in the photofission of209Bi by bremsstrahlung of end-point energies (E0) from 450 to 1100 MeV have been measured using a catcher foil technique with the aid of intensive chemical separation. The charge distribution was well reproduced by a Gaussian function with the most probable charge (Zp) expressed by a linear function ofA,i.e.,Zp=RA+S, and with theA-independent full width at half maximum (FWHMCD). The charge distribution parametersR,Sand FWHMCDwere independent ofE0above 600 MeV, reflecting the resonance nature in photonuclear reactions at intermediate energies. The weighted mean values atE0≥ 600 MeV wereR= 0.421 ± 0.001,S= 0.6 ± 0.1 and FWHMCD= 2.1 ± 0.1 charge unit (c.u.). The numbers of pre- and post-fission neutrons were deduced to be νpre= 12 ± 1 and νpost= 1.4 ± 0.3, respectively, assuming the Unchanged Charge Distribution (UCD). Based on the charge distribution parameters, the symmetric mass yield distributions with the most probable massApof 96 ± 1 mass unit (m.u.) and the width FWHMMDof 33 ± 1 m.u. were also obtained. The characteristics of the charge and mass yield distributions are discussed by referring to those for197Au based on the results of calculations using the Photon-induced Intranuclear Cascade Analysis code combined with the Generalized Evaporation Model (PICA3/GEM).

Target-dependence of light fragment production in photonuclear reactions at intermediate energies

Yields of7Be,10Be,22Na,24Na and28Mg produced fromnatB,natC,natO,23Na,27Al,natSi,natS,natCl,natK,natCa,natV,55Mn,natFe,59Co,natNi,natCu,89Y,natAg,natIn,141Pr,159Tb,165Ho and197Au in irradiations with bremsstrahlung having maximum end-point energies up to 1200 MeV were measured by γ-ray spectrometry (7Be,22Na,24Na and28Mg) and accelerator mass spectrometry (10Be). The yields of heavier fragments,39Cl,43, 44m, 44g, 46, 47, 48Sc,59Fe, and56, 57, 58, 60Co, were also measured by γ-ray spectrometry in order to survey the relative contribution of fragmentation to spallation and/or fission in the mass yield curves. A distinct difference of the target mass-dependence of these yields has made it possible to disentangle the contributions of photospallation and photofragmentation processes. It was found that the neutron-to-proton ratios of targets strongly affect the formation of the nuclei by fragmentation as revealed in the yields of the isotopic pairs as well as of the single isotopes. The photon results were compared with those of proton-induced reactions, and no clear effect due to the difference of the initial interactions of photons and protons with nuclei was found in the fragment yields.

Extraction behavior of rutherfordium into tributylphosphate from hydrochloric acid

The extraction behavior of rutherfordium (Rf) into tributylphosphate (TBP) from hydrochloric acid (HCl) has been studied together with those of the lighter group-4 elements Zr and Hf. The extractability of261Rf,169Hf, and85Zr into TBP was investigated under identical conditions in 7.2–8.0 M HCl by on-line reversed-phase extraction chromatography. The percent extractions of Rf, Hf, and Zr into the TBP resin increase steeply with increasing HCl concentration, and the order of extraction is Zr > Hf ≈ Rf. By considering the order of chloride complexation among these elements, it is suggested that the stability of the TBP complex of Rf tetrachloride is lower than those of Zr and Hf.

Determination of toxic trace elements in foodstuffs, soils and sediments of bangladesh using instrumental neutron activation analysis technique

The concentrations of arsenic (As), chromium (Cr) and iron (Fe) were determined in the foodstuffs, soils and sediments from various areas in Bangladesh and new data for these toxic trace elements were given. The arsenic pollution problems in the most of the areas of Bangladesh are of geological origin. The high level of As in foodstuffs, soils and sediments, except for tannery sediments is probably positively correlated to the Fe concentration. An excessive amount of chromium was found in the sediments from the tannery area of Bangladesh.

Comparative Study of Activation Analyses for the Determination of Trace Halogens in Geological and Cosmochemical Samples

Halogens (fluorine, chlorine, bromine and iodine) were determined by activation analyses (neutron activation analysis (NAA), photon activation analysis (PAA) and prompt gamma-ray analysis (PGA)) for geological and cosmochemical solid samples. We studied how each analytical method was for the determination of trace amounts of halogens in rock samples. Radiochemical NAA (RNAA) showed the highest analytical reliability for three halogens (chlorine, bromine and iodine), whereas a set of four halogens (fluorine, chlorine, bromine and iodine) could be determined in principle by radiochemical PAA (RPAA) from a single specimen. Although it is a non-destructive method, PGA showed an analytical sensitivity for chlorine comparable to those of RNAA and RPAA.

Experimental identification of spin-parities and single-particle configurations in 257No and its alpha-decay daughter 253Fm

alpha-gamma and alpha-electron coincidence spectroscopy for a short-lived heavy actinide nucleus (257)No (T(1/2) = 24.5 s) has been performed using a gas-jet transport system and an on-line isotope separator. Spin-parities of excited states in (253)Fm fed by the alpha decay of (257)No have been identified on the basis of the measured internal conversion coefficients. The nu3/2(+)[622] configuration has been assigned to the ground state of (257)No as well as to the 124.1 keV level in (253)Fm. It was found that the ground-state configuration of (257)No is different from that of lighter N = 155 isotones.

Fluoride Complexation of Element 104, Rutherfordium

Fluoride complexation of element 104, rutherfordium (Rf), produced in the 248Cm(18O,5n)261Rf reaction has been studied by anion-exchange chromatography on an atom-at-a-time scale. The anion-exchange chromatographic behavior of Rf was investigated in 1.9-13.9 M hydrofluoric acid together with those of the group-4 elements Zr and Hf produced in the 18O-induced reactions on Ge and Gd targets, respectively. It was found that the adsorption behavior of Rf on anion-exchange resin is quite different from those of Zr and Hf, suggesting the influence of relativistic effects on the fluoride complexation of Rf.

A new source of basaltic meteorites inferred from Northwest Africa 011

Eucrites are a class of basaltic meteorites that share common mineralogical, isotopic, and chemical properties and are thought to have been derived from the same parent body, possibly asteroid 4 Vesta. The texture, mineralogy, and noble gas data of the recently recovered meteorite, Northwest Africa (NWA) 011, are similar to those of basaltic eucrites. However, the oxygen isotopic composition of NWA011 is different from that of other eucrites, indicating that NWA011 may be derived from a different parent body. The presence of basaltic meteorites with variable oxygen isotopic composition suggests the occurrence of multiple basaltic meteorite parent bodies, perhaps similar to 4 Vesta, in the early solar system.

The strategy for internal carotid stenosis with thrombus

SUMMARY

We report 3 cases of internal carotid artery (ICA) stenosis with thrombus. The initial symptom is transient ischemic attack (TIA) in 1 case, and cerebral infarction due to artery-to-artery embolism in 2 cases.We started anticoagulation and antiplatelet therapy after the angiography on admission in all cases. Carotid endarterectomy (CEA) was performed in 1 case after confirming the disappearance of the thrombus 1 month after the initial attack, although small cerebral embolic infarction happened during this period. In the other cases, percutaneous transluminal angioplasty (PTA) and stenting was performed using the protective technique about 2 weeks after the initial attack without embolic complication. Postoperative angiography showed sufficient dilatation. It seemed that PTA/stenting using the protection system was one of the alternatives for ICA stenosis with thrombus.

Purification and characterization of a NAD+-dependent sorbitol dehydrogenase from Japanese pear fruit

NAD+-dependent sorbitol dehydrogenase NAD-SDH, EC 1.1.1.14) from Japanese pear fruit was purified to apparent homogeneity (single band by SDS-PAGE with silver staining), and had a specific activity of 916.7 nKatal/mg protein. The molecular of the native enzyme was calculated to be 160 kDa by gel filtration, whereas SDS-PAGE gave a subunit size of 40 kDa, indicating that the native enzyme is a homotetramer. The protein immunologically reacted with an antibody raised in rabbit against the fusion protein expressed in E. coli harboring an apple NAD-SDH cDNA. The Km, values for sorbitol and fructose were 96.4+/-8.60 and 4239+/-33.5 mM, respectively, and optimum pH for sorbitol oxidation was 9.0 and 7.0 for fructose reduction. Pear NAD-SDH had a very narrow substrate specificity, that is, sorbitol, L-iditol, xylitol and L-threitol were oxidized but not any of the other alcohols tested. These data suggest the structural importance of an S configuration at C-2 and an R configuration at C-4 in the substrate(s). Its enzymatic activity was strongly inhibited both by heavy metal ions such as mercury, and by thiol compounds, such as L-cysteine. However, the addition of zinc ion reversed the enzyme inactivation caused by addition of L-cysteine.

[Construct validity of a new computer-assisted cognitive assessment battery in normal adults]

A computer-assisted battery for neuropsychological tests (CNT) has been designed to screen adults for cognitive impairment. The aim of this study was to gather evidence for the construct validity of CNT and also investigate the relationship between CNT and conventional neuropsychological tests. Subjects were 45 healthy adults (21 men and 24 women), who ranged in age from 20 to 70 years (mean = 33.5, SD = 1.9) with no history of substance abuse, or of psychotic or neurological disorders. The CNT in our study consists of six subtests designed to assess various components of driving, such as digit span, visual scanning, visual and verbal memory, complex reaction time, and vigilance. Mini-mental state test, Kana-hiroi test, word fluency, the auditory-verbal learning test and Raven's colored progressive matrices were also performed as conventional neuropsychological tests. Results showed there were high correlations between each CNT subtests and conventional neuropsychological tests. A factor analysis (with varimax rotation) identified 4 factors with eigen values greater than 1, which accounted for over 70% of the variance. CNT was able to estimate each factor related to cognitive function such as learning and memory, attention, judgment, and visual scanning selectively. CNT may thus be a useful tool for detection of cognitive impairment, although this test has important limitations. Broader applications of these tests will require extensive population-based validation.

Cloning of NAD-dependent sorbitol dehydrogenase from apple fruit and gene expression

Partial amino acid sequences of NAD-dependent sorbitol dehydrogenase (NAD-SDH) were used to identify a full-length cDNA from apple fruit. This clone consisted of 1,433 bp containing an open reading frame of 1,137 bp that could code for a polypeptide with 379 amino acids. To our knowledge, this is the first report about cloning of NAD-SDH cDNA from a plant source. The deduced amino acids from cDNA revealed 43.7% identity to human NAD-SDH. The activity of this enzyme to convert sorbitol to fructose with the reduction of NAD was certified by the fusion protein of this clone expressed in Escherichia coli. Northern blot analysis showed that the mRNA was expressed in matured apple fruit.