Narrow Results

Priming X-irradiation with 0.3-0.5 Gy induces radio-resistance in C57BL/6 strain of mice 2 weeks afterward. Elements in the bone marrow, sampled 11 days after challenging exposure to 5.0 Gy, were determined by PIXE. The challenging irradiation decreased Mg, P, S, K, Ca and Zn as well as dried bone marrow weight. The pre-irradiation enhanced recovery of these levels, indicating stimulated recovery of the metabolism in the tissue. Fe in both control (without pre-irradiation) and experimental groups increased to about twice the original value, showing elevated hemoglobin synthesis after challenging exposure. In previous studies we have reported that recovery of peripheral blood cell counts after sub-lethal irradiation was enhanced by the pre-irradiation. Further, study on accumulation of p53 and Bax proteins, which lead to apoptotic cell death, revealed that the pre-irradiation significantly suppressed accumulation of these proteins in the spleen after challenging irradiation with 3 Gy. These results and our present study suggest that the pre-irradiation decreased the spleen cell death, and favored re-growth of the spleen cells, resulting in stimulated recovery of metabolism for hematopoiesis in the bone marrow as well as in the spleen after challenging high dose irradiation. Stimulated recovery of Mg, P, S, K, Ca and Zn levels might indicate the importance of these elements in hematopoiesis.

Marine micro-algae (Nannochloropsis sp., and Phaeodactylum sp.,) were obtained from the Pacific Ocean of Iwate Pref., Japan and purely cultured in nutritive seawater as a culture solution. The culture size for algae was 10 - 250 ml and every apparatus was small and of low cost. Marine micro-algae were given in different culture solutions including Pb²⁺ from 0.01 to 1.0 mg /l. The algae in 5 ml of the culture solution were collected on a polycarbonate filter (pore size : 1.0 μm) by suction filtration. The algae on the filter were subjected to PIXE analysis. Concentrations of Na, Mg, Si, P, S, Cl, K, Ca, Cr, Mn, Fe, Cu, Zn, Sr and Pb were simultaneously determined. PIXE can do multi-element analysis for a sample of below 1 mg. The quantity of lead in marine micro-algae increases in proportion to the Pb²⁺ concentration in the culture solution. The concentration factor (wet weight base) for lead is given as 200 ± 20 ml / g for Nannochloropsis sp. and 1900 ± 400 ml / g for Phaeodactylum sp.. It is shown that PIXE is a powerful tool for the measurement of the bioaccumulation of trace elements.

Bio-medical implants release metallic elements during the long periods of time while inserted in the human body. The chemical interactions between the tissues and surface of the implants, and the mechanical friction of implants cause the release of metals into the human tissues. In this study we investigated the distribution and the chemical-state of the metallic elements in the tissues around a failed implant system using PIXE (proton induced x-ray emission) and SR-XRF (synchrotron radiation x-ray fluorescence) spectroscopies. The specimens were from the cases of patients with diagnosed arthritis. The implant consisted of a stem and a metal backing made of Ti-6Al-4V, an implant head made of stainless steel, and a polyethylene (PE) cup. Both the stem and the metal backing had a plasma-sprayed HAp surface coating. Distribution and concentration of dissolved elements in tissues surrounding implants were examined and quantified using PIXE analysis. Similar specimen from the same case was further investigated using SR-XRF analysis. Chemical-states of the dissolved elements ware also studied by XAFS (x-ray absorption fine structure) analysis. From results of these measurements, it is confirmed that the tissues surrounding implants contained metallic elements such as Fe, Cr, Ni, and Ti. These elements are originated from the implant. Furthermore, it was made clear that the chemical-state of Fe had changed as a consequence of dissolution of Fe in the organic tissues.

Transition metal elements and others in river water sample supplied by The Japan Society for Analytical Chemistry (JSAC) were determined by PIXE using 2.5 MeV proton beam at the Tokyo Institute of Technology Van de Graaff Laboratory. The relative detection efficiency for each X-ray of element and its recovery were studied in two methods: "Drop and Dry" and "Concentration" methods. Ten elements (V, Cr, Mn, Fe, Ni, Cu, Zn, As, Se and Pb) were determined, being in good agreement with the values certified by JSAC except for Mn. Intensity of K_α X-ray of As and L_α, X-ray of Pb nearly close to each other could be successfully evaluated using isolated L_β X-ray of Pb. Mn was insufficiently recovered to give lower content than the certified value in the present conditions. V that is not listed in the certificate was found to show good agreement with that reported previously. Concentration method using sodium dibenzyldithiocarbamate only could be successfully employed for collecting these elements.

In March 1999, electrostatic accelerator, Tandetron (Model 4117MC, High Voltage Engineering Europe Co.) was installed in the Electrostatic Accelerator Building for PIXE (Particle Induced X-ray Emission) analysis. The accelerating voltage is 0.4 to 1.7MV, and the maximum beam current is 5μA at 3.4MeV. This system has three beam ports for different types of PIXE analysis: normal, micro-beam and in-air. The first beam port is used for normal PIXE. Since two types of X-ray detecting device, Si (Li) and CdZnTe detectors, are available here, elements from Na (Z=11) to U (Z=92) are detectable. Fifteen samples can semi automatically be measured at one time using a proton beam of optical beam size from 0.5 to 2.0 mm at 100 nA beam current. A quadrupole triplet magnet (Model OM2000, Oxford Micro beams, Ltd.) attached to the second beam port produces a proton micro-beam of square shape less than 1μm×1μm. Micro-beam scanning PIXE analysis is carried out with this beam at 50pA current and scanning area up to 2.0mm square. The in-air PIXE analysis is performed using the third beam port. The operation of this machine has been scheduled to start from April 2000 and is controlled by Division of Technology and Safety. Some results preliminarily obtained are also shorn.

A new x-ray-spectrum-analysis program, which is capable of fitting with response functions including a tail function, an escape peak and sub-lines, has been developed. In this code, the tail function is expressed by combination of two or three Gaussian functions. A tail function, an escape and sub- or satellite-lines are regarded as functions belonging to the main peak and are included in it. A small shift of peak position depending on measuring conditions can be easily corrected in the program. As a result of fitting to practical spectra with the response function thus prepared, it becomes possible to draw a smooth background over a wide x-ray-energy range and to analyze a whole spectrum simultaneously. Thus, accuracy and reproducibility of a spectrum analysis are much improved. By means of this code, correct values of peak yield of Co-Kα, which overlaps with the tail of Fe-Kβ and is quite difficult to be accurately separated by fitting with Gaussians, have been obtained. Furthermore, accuracy of peak separation of a small peak, which overlaps with the escape peak belonging to a huge peak, has been improved. Accuracy of quantitative analysis for high-Z elements by means of Kβ yields has also been improved by using the response function including sub-lines, and it became possible to accurately separate small Kα lines from Kβ lines of the other elements.

Canine teeth of northern fur seals were analyzed by PIXE to examine relationship between trace elements in fetal teeth and those in mother's teeth. The trace elements including Mn, Fe, Zn and Sr were detected in all the sample. No significant difference was detected in the mean concentration of Mn between fetal teeth and mother's teeth. On the other hand, significant difference was detected in the mean concentration of Fe, Zn and Sr between the enamel tissue in fetal teeth and the enamel tissue in mother's teeth. Additionally, difference in the change of concentration was detected among elements: Fe concentration in enamel tissue has no relation to ages, Zn concentration in enamel tissue decreases with age and Sr concentration in enamel tissue increases with age. The fluctuation of trace elements is possibly affected by seal's migration route and / or the mechanism of the element transfer from maternal sera to fetus through the placenta.

In order to study influence of automobile traffic on a local urban atmospheric environment, we have investigated suspended particulate matter (SPM) collected at sampling sites in a region which includes a major highway and a residential area in the southern part of Tokyo during August - November 1999. The atomic composition of each sample was measured by means of PIXE analysis using a 2.0 MeV proton beam. Sixteen elements were quantitatively measured. The positional dependence of SPM loading was determined for each element using samples simultaneously collected at three different sites. For the experimental results obtained for downwind conditions, the measured concentration as a function of the distance from the highway was compared with a simple calculation based on the Gaussian plume model. The concentration distribution of some heavy elements in the fine fraction is well reproduced by this analysis. It has been found that for ordinary moderate downwind conditions the area within 300-400 m from the highway is directly affected by emission due to the automobile traffic.

Ashes generated in the incinerator for radioactive waste at the Kaya Memorial Takizawa Laboratory was analyzed using the PIXE system established at the Nishina Memorial Cyclotron Center. An easy method of sample preparation of ash powder for the PIXE is described. Many elements in the ash sample were detected. The PIXE used in this study is shown to be a very valuable method for analyzing the ash.

Selenium in industrial wastewater at sub-ppm level was determined by PIXE spectrometry at the Tokyo Institute of Technology Van de Graaff Laboratory using a 2.5 MeV proton beam. A chemical concentration method was applied for elemental analysis. Other elements (Mn, Fe, Ni, Cu, Zn, Pb, Hg, Cd, As) were also found simultaneously. Anion chromatography revealed that selenium forms an oxyanion SeO₃^2- in wastewater studied. Pb, As and Se of these chemical species are required to lower below the discharge standard to the public water, 0.1ppm, while that of Hg is 0.005ppm. The combined use of these two analysis tools will help for rapid monitoring of the quality in the public water environment.

Effects of supplementation by copper(I) and copper (II) in Long-Evans Cinnamon(LEC) rats and life survival of rats are given. Long-Evans Cinnamon(LEC) strain rats were used at age of 8 weeks. The rats were randomly assigned to either copper(I) chloride or copper (II) chloride group. We have performed x-ray emissivite determination of copper in liver of LEC rats using PIXE and detected increase in copper in liver at early stage which could be supplemented by copper(I) and copper (II). During the supplementation period, clinical deterioration continued accompanied by daily body sway. The rats lost an undetermined amount of body weight and died approximately fourteen days later.

PIXE technique has been utilized to analyze some obsidian artifacts found in the Southern Platform of the ceremonial center of Lagunillas, Michoacán, México. According to their chemical composition, the provenance of obsidian was established, thereby confirming the commercial routes of the Lagunillas region during Early (A. D. 900-1200) and Late Postclassical periods (A. D. 1200-1523).

Total suspended particulate (TSP) samples were collected at the west-facing slope (altitude 700 m) of Mt. Moriyoshi in northern Japan, from 24 – 27 June (non-snow-clad period) and 11 – 14 December (snow-clad period) in 1996, with a one-hour sampling interval. The elemental composition and particle shape of TSP samples were determined and/or observed by Particle Induced X-ray Emission (PIXE), a Scanning Electron Microscope (SEM) combined with Energy Dispersive X-ray (EDX) analysis. In the hourly TSP samples collected during the non-snow-clad period, 27 elements were determined. Na, Mg, Al, Si, S, K, Ca and Fe were found to be the major elemental components. On the other hand, 25 elements, excluding Nd and Mo, were found in the snow-clad period samples, and Cl is a dominant element, i.e., a major element, of the snow-clad period samples, unlike the non-snow-clad period. Comparing the arithmetic means of concentrations of major elements in TSP for non-snow-clad and snow-clad periods, Mg, Al, Si, K, Ca and Fe levels in the snow-clad period are 2 – 4 times as much as those in the non-snow-clad period, and 30 times for Na. S is similar. For temporal variation patterns of element concentrations, the non-snow-clad period is different from the snow-clad period. Al, S, Ca, Ti, Fe, Zn and Pb are similar throughout the non-snow-clad period, and Al, Si, Ca and Fe are similar throughout the snow-clad period. With the aid of SEM and EDX analysis, aggregates of car exhaust particles, soil particles and plant spores were observed in the non-snow-clad period samples. In the snow-clad period samples, small silicon-rich spherical particles, aggregates of car exhaust particles and soil particles were observed.

The contribution to the atmospheric pollution in Mexico City's conurbation that comes from the northern area has been considered significant for a long time. Therefore, it is important to determine its elemental composition as well as their correlation in sites along the suspected trajectories of airborne particulate matter. Samples were collected simultaneously in two sampling sites along the prevailing wind trajectory in northern Mexico City, and its elemental composition were determined by PIXE. The Sample collection was performed daily from 17 February 14 March 1997 in Xalostoc, an industrial zone in the State of Mexico, and Ticomán within Mexico City. Two samples a day were taken in two periods: 7-19 h and 19-7 h. The samplers used separated particles into two particle size fractions fractions, PM₂₅ and PM₁₅. Three main correlation group of elemental concentrations were determined: fuel combustion, earth crust and industrial origin. The sampling site within Mexico City, Ticomán, was found with an overall tendency of higher elemental concentrations, showing not only influence of local pollution sources, but also that of wind transported particles from neighboring industrial zones such as Xalostoc.

In order to study the influence of motor vehicles on a local soil environment, depth profiles of elemental concentration of urban roadside soil were investigated by means of thick-target PIXE analysis. For comparison, we analyzed the soil sampled in a university campus with very low traffic intensity. From the measured depth profiles, it was found that the roadside surface layers up to the depth of approximately 5 cm from the ground level are highly polluted by S and Zn. According to cluster analysis this pollution can be attributed to the deposition of tire dust due to the heavy vehicular traffic volumes on the highways.

The MicroPIXE technique was employed to reveal detailed distributions of trace elements in the testis, which distinguish the cell type-differences corresponding to the germ cell development (the 14 designated stages of the seminiferous epithelium cycle). Clear elemental imagings were obtained for P and S with a 50 μ m-thick section; S was higher in elongated spermatids in stages VII-VII, where a lower level of P was observed. Elemental imagings of Cu, Fe, Mn, Se, and Zn were obscure compared with P and S, but information about their localization in the seminiferous epithelium was obtained. These results suggest that microPIXE analysis is a powerful technique for investigation of elemental dynamics in the testis, although an improvement of detection for testicular trace elements is required.

Total suspended particulate (TSP) samples were collected along a highway (Barajima air pollution monitoring station) in the center of Akita City in northern Japan, from 9 – 11 May, 1996 (non-snow-clad period) and 7 – 9 February, 1997 (snow-clad period), with a one-hour sampling interval, The elemental composition and particle shape of TSP samples were determined and / or observed by Particle Induced X-ray Emission (PIXE) and a Scanning Electron Microscope (SEM) combined with Energy Dispersive X-ray (EDX) analysis. In the hourly TSP samples collected during the non-snow-clad period, 26 elements were determined. Na, Mg, Al, Si, S, Cl, K, Ca and Fe are the major components. On the other hand, 24 elements, excluding As, Rb and Nb, are found in the snow-clad period samples, and Gallium is only found in the snow-clad period samples. Dominant elements, i.e., major components, of the snow-clad period were the same as the non-snow-clad period. Comparing the arithmetic means of major elemental concentrations in TSP for the non-snow-clad and snow-clad periods, Na, Mg, Al, Si and Fe are similar. However, S and Ca levels in the non-snow-clad period samples were 4 and 6 times higher than those in the snow-clad period samples, respectively, while Cl and K levels in the snow-clad period samples were 1.5 and 2 times higher than those in the non-snow-clad period, respectively. In the non-snow-clad period, the temporal variation pattern of total elemental amount was consistent with the variation pattern of NO and CO, which are pollutants used to observe the effects of automobile exhaust gas, and it was comparatively consistent with the variation pattern of SPM. On the other hand, in the snow-clad period, the temporal variation pattern of total elemental amount was not consistent with the variation pattern of NO and CO when the wind was blowing from the southeast, so the TSP may be strongly influenced by wind direction and wind velocity in addition to automobile traffic. Factor analysis allowed us to identify four major sources, with automobile emission, industry and soil being the major contributors. With the aid of SEM and EDX analysis, aggregates of diesel exhaust particles (DEP), soil particles and small silicon-rich spherical particles were observed in the non-snow-clad and snow-clad period samples.

A standard-free method of quantitative analysis, which is based on the fact that the total yield of continuous x-rays from the sample approximately corresponds to effective weight of the sample, was developed and has been applied to some typical bio-samples such as serum, whole blood, hair and untreated bone. In this work, the standard-free method was applied to untreated urine samples. This method allows us to perform sample preparation only by dropping 5 μl of urine sample onto a backing film. It requires neither a large amount of urine nor the internal standard. As the results, values of concentration of potassium for 4 samples agree well with the value obtained by the internal standard method within an error of 10%. The present method was also applied to 21 urine samples containing excess amount of urinary protein and / or sugar, and it is found that the present method is applicable to such abnormal urines. Owing to this method, target preparation can be performed at the place and time of sampling. It is quite convenient to environmental studies.

The study of single raindrops is expected to give new and great information such as drop formation processes and pollutant scavenging mechanisms. To investigate the characteristics of individual raindrops, PIXE method was applied to elemental analysis. Size-segregated individual raindrops were collected at Kyoto University during rain event in October 2001. Detection limit of each element for polycarbonate filter used as the substrate of raindrops was calculated. The significant peaks of several elements in single raindrop corresponding to the channel number of PIXE could be resolved. Chlorine, potassium, and sulphur were found as major elements in each size raindrop. Strong raindrop size-dependence of every elemental concentration was shown. Chlorine, chromium, potassium, and calcium show the distinctively high scavenging rate at the beginning rainfall. They show 98 %, 97 %, 96 %, and 84 % scavenging rate, respectively and followed by iron and sulphur.

The groundwater pollution by arsenic in Bangladesh causes a serious problem for millions of people who are exposed to poisoning by this toxic element. In an attempt to evaluate the extent of arsenic poisoning, hair samples of people living in Pabna district were collected. The hair samples were analyzed using Proton Induced X-ray Emission (PIXE) through exciting the atoms of a specimen so that their intensities can be converted into elemental concentrations in the specimen. The elements present in the specimen are identified by the corresponding X-ray energies and their concentrations are deduced from the X-ray intensities. The results from hair samples indicate substantially higher level of arsenic than those demarcated as toxic levels, in people from member families both affected and non-affected by poisoning. We correlate it with exceedingly high arsenic concentration in drinking water far above the permissible limit. The analytical results are compared with the results of arsenic and other elemental analysis of 160 Bangladeshi hair samples with that of 250 Japanese samples. The results show markedly higher levels of arsenic, manganese, iron and lead where the latter three elements show a positive relation with arsenic in the case of Bangladeshi as compared to the samples from Japan. On the other hand, selenium concentrations show very low level in the Bangladeshi samples compared to Japanese, displaying an inverse relationship with arsenic. The mechanism of arsenic in relation to other elements in the human body needs further investigation. The preliminary results call for detailed experimental and epidemiological studies to further characterize these aspects.