International Journal of PIXE

Selenium (Se) concentrations in plasma, urine, and feces were determined by PIXE analysis before and after intravenous (iv) / oral (po) administration of sodium selenite (a dose equivalent to 2 mg/kg of selenium) to rats. The concentration-time profiles of Se were analyzed by a pharmacokinetic approach. The plasma Se profile after iv injection was biphasic and well-fit to a 2-compartment open model, showing two half lives (t1/2). The first t1/2 was about 0.3 hr and the second t1/2 was 6.9 hrs. The plasma concentration reached almost basal level after about 80 hrs of injection. On the other hand, plasma profiles after po administration showed absorption rate-limiting elimination. The bioavailability of oral sodium selenite (about 49%) and significantly higher amount of fecal Se excretion indicated relatively poor intestinal absorption of sodium selenite, compared to the previously published data. Urinary Se excretion was almost comparable between iv and po groups. The total recovery of the dose excreted in urine and feces was 30 ± 10 % in iv and 56 ± 15 % in po group. The renal excretion was considered to be a major route of Se excretion after absorption. Significant amount of Se that was not fully excreted was noted, suggesting Se distribution or accumulation in organs, together with volatile excretion.

The abnormal cell exit of apoptosis from S-phase, correlation between apoptosis and Mg, and between its S-phase fraction and Zn were studied in inoculated Sarcoma-180 receiving 10 or 20 Gy of ⁶⁰Co gamma ray, IN VIVO, in BALB/c mice.

The apoptosis and S-phase fraction were detected by double immunostaining: 1) TUNEL that colors apoptosis brown; and 2) histone H3 mRNA probe that results in blue deposition to S-phase of cells. The concentrations of Mg and Zn were studied by PIXE.

The Mg strongly correlated with the frequency of apoptosis, but other kinds of cells did not. On the contrary, The S-phase fraction of apoptosis did not correlated with Zn, but S-phase of other kinds of cells did. This different correlation suggests the different metabolism between apoptosis and other kinds of cell.

Pre-irradiation with 0.3-0.5 Gy of X-rays induces radioresistance (decreased bone marrow death) in ICR and C57BL strains of mice 2 weeks afterward. Recovery of blood cell counts of thrombocytes, leukocytes and erythrocytes was enhanced by the pre-irradiation. And the radio-resistance is acquired even in splenectomized C57BL mice. Elements in the bone marrow 11 days after the challenging dose of 5.0 Gy was determined by a PIXE analysis in three groups of mice: intact (with no irradiations), without pre-irradiation (control) and pre-irradiation (experimental) groups. Challenging irradiation decreased Mg, P, S, K, Ca and Zn levels, and the pre-irradiation enhanced the recovery of those levels, i.e. stimulated metabolism in bone marrow of irradiated mice. Increase in Fe in both control and experimental groups would indicate stimulated hemoglobin synthesis after challenging irradiation.

The purpose of this study is to clarity how trace elements in gastric mucosa, reflex bile acid and inflammation of gastric mucosa relate to environment of Helicobacter Pylori.

Subjects were 33 patients who had colonic endoscopic examination. 11 gastric ulcer and 14 duodenal ulcer patients were chosen as subjects of the study. The control group had 8 members who had no localized lesions. Trace elements were measured by PIXE analysis which use Pd as internal standard.

Cu and Zn, especially Zn, were found in large amount in gastric body and antrum. Zn value for the antrum was higher than that for the gastric body.

Especially, the values of Zn for antrum showed significant differences between grade I, II and grade III of inflammatory cell infiltration.

In gastric ulcer group, the value of Cu indicated high at gastric body and low at antrum. On the other hand, the values of Zn were low at both gastric body and antrum.

Particularly, development of atrophy in antrum requires less than one in gastric body; therefore, trace elements decreased in gastric ulcer group.

Trace elements in shells of short necked clams were analyzed with PIXE. Two groups of the shells ware sampled from high salinity and low salinity. Strontium (Sr) and Iron (Fe) concentration ware significantly different between the two groups. Although water temperature and salinity may affect Sr concentration in the shells, the Sr concentration was higher in better growth clams.

Strontium (Sr) concentration in the shells of short-necked clams collected at different locations (Shirahama, warm area and Maizuru, cold area, Japan) was analyzed by two methods, PIXE and EPMA. The Sr concentration of external surface of shell umbo, which was made during short term at early benthic phase, was analyzed by PIXE, and was ranged from 1000 to 3500 ppm for individuals. The Sr concentration of clams collected at Shirahama showed positive correlation with shell length (SL) in individuals with SL <31mm, whereas clams collected at Maizuru did not show significant correlation. This result may be caused from the difference of the spawning seasons between two areas. The Sr concentration of cross section of shell umbo, which develops thicker continuously during their life to form faint stratum structure, was analyzed by EPMA along the line across the stratum structure. Some surges and long term waving patterns of the Sr concentration were observed. These results suggest that the life histories of individual clams could be recorded in the shell umbo cross sections as variations of trace elements and analyses of trace elements could clarify the histories of individual clams.

Distribution profiles of Sr injected into the stem of a Japanese cedar (Cryptomeria japonica D. Don) were determined using PIXE. The Sr injected into the middle of the sapwood of the cedar stem moved upwards easily along the grain. The movement of the Sr in a radial direction in the stem (assumed to be through the ray) was small and there was almost no tangential movement.

Fresh surface snow samples were collected at the summit or near the summit (700 - 1500 m altitude) of five mountains in Akita Pref., Japan. The elemental composition and particle shape of insoluble material in these snow samples was determined and/or observed by Particle Induced X-ray Emission (PIXE), a Scanning Electron Microscope (SEM) combined with Energy Dispersive X-ray (EDX) analysis. 21 kinds of elements for each mountain snow sample were determined by PIXE. Na, Mg, Al, Si, P, S, Cl, K, Ca, Ti and Fe were the major components in each of the mountain snow samples, and those in relative abundance were almost the same in each case. With the aid of SEM and EDX analysis, silicon-rich small sphere (spherule) particles and aggregates of car exhaust particles were observed in every mountain snow sample. These results are represented as insoluble components of clouds and provide important knowledge for the source and mechanism of snowfall and rainfall at the ground level.

Two types of music pipes, Ginteki and Suifûkin, that were popular during the late Meiji period in Japan were semi-quantitatively analyzed by the external-PIXE at RIKEN. The aim of this study is to identify the material used for these pipes and to assist the description to make an instrumental catalogue. Our results show that most of the collected Ginteki, literally silver flute, is composed of two parts. One is the whistle head of Pb-Sb alloy with the Pb to Sb ratio between 5.9 and 6.4; and the other is the main body with six holes which is made of tinplate. All of the Ginteki in this study are nickel coated. The Suifûkin, on the contrary, is made of only tinplate and is not coated with nickel.

Each concentration of specific elements in water extracted from the ash produced by an incinerator used for radioactive waste at the Kaya Memorial Takizawa Laboratory was simultaneously determined using PIXE established at the Nishina Memorial Cyclotron Center. Each concentration of the elements extracted from the ash depends on the pH of the water. The PIXE used in this study was shown to be a very valuable analytical method for environmental analysis.

EDS-PIXE is a very useful and easy method for detecting trace elements in ancient materials. However, relatively high continuous background is observed, when old copper alloys are measured under 4 MeV protons. The background makes the detection limits of trace metallic elements such as Au, Ag, As, Sn, Sb and Pb in these alloys worse. The cause of the high background was investigated using a Si(Li) detector, a pure-Ge detector and a ³He neutron counter, and it was found that the continuous background level is correlated with the amount of neutron released from ⁶⁵Cu(p,n)⁶⁵Zn reaction.

A method of quantitative analysis which is capable of analyzing powdered samples consisting of high-Z elements, such as ash, soil and aerosol, is developed. It is confirmed that an internal standard method using a powdered internal standard, which has almost the same particle size as that of a sample, gives quantitative values of concentration with satisfactory accuracy and reproducibility. It was successfully applied to standard samples such as NIST-Urban particulate matter (1648), GBW-Tibet soil (08302), BCR-City waste incineration ash (0497) and also to a practical fly-ash sample. As a result, it is found that the effect of self-absorption in the target is not negligible even for samples whose particle size is less than 4 μm, and a method of correcting it is established. Firstly, the effective thickness for self-absorption is estimated by comparing peak yields of a certain element for two measuring conditions of beam irradiation from the surface and from the back of the target. The correction factors can be estimated by using the effective thickness, values of concentration of principal elements and their photon absorption cross sections. For practical samples whose compositions are unknown, it is confirmed that accurate correction coefficients can be derived by carrying out an iterative calculation until a self-consistent solution between values of concentration of the main constituents and the correction factors is obtained.

We developed a system of μ-PIXE analysis at the division of Takasaki ion accelerator for advanced radiation application (TIARA) in Japan Atomic Energy Research Institute (JAERI), which consists of a microbeam apparatus, a multi-parameter data acquisition system and a personal computer. Elemental analysis in the region of 500 μm × 500 μm can be performed with a spatial resolution of < 0.3 μm and multi-elemental distributions are presented as images on a computer display even during measurement. We call this system a micro-PIXE camera.

We developed a PIXE analysis system which provides spatial distribution images of elements in a region of several cm² with a spatial resolution of < 0.5 mm. We call this system a submilli-PIXE camera. This system consists of a submilli-beam line, beam scanners and a data acquisition system in which the X-ray energy and the beam position are simultaneously measured. We demonstrate the usefulness of the submilli-PIXE camera by analyzing the surface of a shell and of granite.