Induced X-ray Emission Research Articles

Methods of chemical and phase composition analysis of gallstones

This review presents the instrumental methods used for chemical and phase composition investigation of gallstones. A great body of data has been collected in the literature on the presence of elements and their concentrations, obtained by fluorescence microscopy, X-ray fluorescence spectroscopy, neutron activation analysis, proton (particle) induced X-ray emission, atomic absorption spectroscopy, high-resolution gamma-ray spectrometry, electron paramagnetic resonance. Structural methods—powder X-ray diffraction, infrared spectroscopy, Raman spectroscopy—provide information about organic and inorganic phases in gallstones. Stone morphology was studied at the macrolevel with optical microscopy. Results obtained by analytical scanning and transmission electron microscopy with X-ray energy dispersive spectrometry are discussed. The chemical composition and structure of gallstones determine the strategy of removing stone from the body and treatment of patients: surgery or dissolution in the body. Therefore one chapter of the review describes the potential of dissolution methods. Early diagnosis and appropriate treatment of the disease depend on the development of clinical methods for in vivo investigation, which gave grounds to present the main characteristics and potential of ultrasonography (ultrasound scanning), magnetic resonance imaging, and X-ray computed tomography.

The effect of segregation and thermodiffusion on the formation of interfaces in nanostructured (Ti-Hf-Zr-V-Nb)N multielement coatings

Superhard nanostructured multielement coatings based on (Ti-Hf-Zr-V-Nb)N composition have been studied before and after thermal annealing at 600°C. It has been established that capture of positrons on defects takes place at the boundaries of nanograins and on interfaces (vacancies, nanopores, triple and higher-order joints of nanograins). Three-dimensional maps of the distribution of elements in super-hard coatings have been obtained using micro-proton-beam induced X-ray emission (μ-PIXE) measurements. Analysis of the μ-PIXE elemental profiles and defect profiles (obtained using a focused positron beam) helps understanding the physical picture of processes related to the formation of interfaces and sub-boundaries in nanostructured (Ti-Hf-Zr-V-Nb)N coatings.

UV and humidity sensing properties of ZnO nanorods prepared by the arc dischargemethod

The UV and humidity sensing properties of ZnO nanorods prepared by arc discharge have beenstudied. Scanning electron microscopy and photoluminescence spectroscopy were carriedout to analyze the morphology and optical properties of the as-synthesized ZnO nanorods.Proton induced x-ray emission was used to probe the impurities in the ZnO nanorods. Alarge quantity of high purity ZnO nanorod structures were obtained with lengths of 0.5–1 µm. The diameters of the as-synthesized ZnO nanorods were found to be between 40 and400 nm. The nanorods interlace with each other, forming 3D networks which make themsuitable for sensing application. The addition of a polymeric film-forming agent (BASFLUVISKOL® VA 64) improved the conductivity, as it facilitates the construction of conducting networks.Ultrasonication helped to separate the ZnO nanorods and disperse them evenly through the polymericagent. Improved photoconductivity was measured for a ZnO nanorod sensor annealed in air at200 °C for 30 min. The ZnO nanorod sensors showed a UV-sensitive photoconduction,where the photocurrent increased by nearly four orders of magnitude from2.7 × 10−10 to1.0 × 10−6 A at 18 V under 340 nm UV illumination. High humidity sensitivity and goodstability were also measured. The resistance of the ZnO nanorod sensor decreasedalmost linearly with increasing relative humidity (RH). The resistance of theZnO nanorods changed by approximately five orders of magnitude from4.35 × 1011 Ω in dry air (7%RH) to about 4.95 × 106 Ω in 95% RH air. It is experimentally demonstrated that ZnO nanorods obtained by the arcdischarge method show excellent performance and promise for applications in both UV andhumidity sensors.

Intracellular changes of metal elements by fucoidan extracted from brown seaweed (Cladosiphon okamuranus).

This study was undertaken to elucidate the intracellular changes of metal elements after the administration of fucoidan extracted from Cladosiphon okamuranus. TRL1215 cells (normal rat liver cell line) were treated with 0, 0.1, or 1.0 mg/ml fucoidan and incubated in 5% CO2 at 37 degrees C. The cellular levels of Mg, Al, Fe, and Zn were significantly increased in the 1.0 mg/ml fucoidan-treated cells compared to those of the 0.1 mg/ml fucoidan-treated cells and the control. Next, TRL1215 cells were cultured on Mylar film overnight. At 24 h after 5-bromo-2'-deoxyuridine dosing, 0, 0.1, or 1.0 mg/ml fucoidan was treated for 9 h. The cellular distribution of elements was analyzed using in-air micro-micro-particle induced X-ray emission. The X-ray spectra showed that yields of Al, Mg, and Zn were high in order of the 1.0 mg/ml fucoidan-treated sample, the 0.1 mg/ml fucoidan-treated sample, and the control. Fe yield was mildly increased by fucoidan administration. In fucoidan-treated cells, the focal accumulation of Br was correlated spatially with phosphorous-rich region, suggesting that Br was localized within the nucleus. Al distribution provided a spatial association with Br map. These data suggest that fucoidan increases the accumulations of Al, Mg, Fe, and Zn in normal rat hepatocytes, and fucoidan-binding Al is postulated to be transferred into the nucleus.

Cellular distribution and localisation of iron in adult rat brain (substantia nigra)

Iron appears to be one of the main factors in the metal induced neurodegeneration. Quantitative information on cellular, sub-cellular and cell specific distributions of iron is therefore important to assess.The investigations reported here were carried out on a brain from an adult rat. Therefore, 6μm thick embedded, unstained brain sections containing the midbrain (substantia nigra, SN) were analysed.Particle induced X-ray emission (PIXE) using a focussed proton beam (beam – diameter app. 1μm) was performed to determine the quantitative iron content on a cellular and sub-cellular level.The integral analysis shows that the iron content in the SN pars reticulata is twice as high than in the SN pars compacta.The analysis of the iron content on the cellular level revealed no remarkable differences between glia cells and neurons. This is in contrast to other studies using staining techniques.

Source Apportionment of Indoor PM2.5 and PM10 in Homes

A source apportionment analysis was performed using the elemental species concentrations of the air particu late samples collected in 8 homes from October 1999 to March 2000. It was based on a chemical mass balance approach using the source profiles from five common sources found in Hong Kong homes. These five sources were smoking, cooking, incense burning, human activi ties and outdoor contribution. Seventeen elements were analysed in the particulate samples collected by proton- induced X-ray emission. The results showed that cook ing contributed on average 61.9% of the total indoor PM2.5 in the 8 homes with 31.9% on average contributed from the outdoors. In contrast, the major contributor to the indoor PM10 load was the outdoor contribution, which was 49.3% on average followed by human activi ties, which totalled 29.9% on average.

Mapping of light elements with the ANSTO high energy heavy ion microprobe

7.62 MeV He was used to study the distribution of a wide range of elements in mineral sands. At this energy both He induced X-ray emission and a high energy resonance in oxygen can be applied simultaneously. The two techniques were used to study the distribution of elements ranging from sulfur to zirconium as well as oxygen.

PIXE (Particle/Proton Induced X-ray Emission) : a Powerful Quantitative Tool for Mineral Exploration

PIXE (Particle/Proton Induced X-ray Emission) : a Powerful Quantitative Tool for Mineral Exploration

Elemental composition of atmospheric aerosol particles under different conditions in Hungary

Aerosol samples were collected simultaneously by means of Nuclepore filters at three sites with different pollution levels: in downtown Budapest, in suburban Budapest and in rural air in Hungary. The concentration of 18 elements with atomic numbers between 13 and 82 were determined in the samples by particle (proton) induced X-ray emission (PIXE) method. The concentrations obtained are discussed, and dry deposition rates calculated on the basis of transport model simulations are compared to the wet depositions measured. It is found that the concentration and enrichment factor of different elements increased generally from background to downtown and wet removal significantly controls the deposition of anthropogenic elements.

Induced X-ray emission from neon implanted into metals

The physical state of non implanted into different metals has been studied by means of soft X-ray emission spectroscopy. Metal samples (beryllium, aluminiu, titanium, chromium, iron, copper, zinc, molybdenum, silver, tungsten, gold, lead and bismuth) are implanted with 50 keV neon ions ( 20Ne +) and subsequently irradiated with 4 keV electrons to excite the neon X-ray fluorescence which is analysed with a flat-crystal spectrometer. A considerable broadening of the atomic K X-ray line is observed for all samples, showing the existence of a band structure. The observed 2p band width W ranges between 1.95 and 4.07 eV depending on the host metal (compared with 1.3 eV for solid neon at atmospheric pressure). X-ray fluorescence analysis yields two observations (the total width W and the spectrum shape) which should be related to the following macroscopic parameters: the average metal shear modulus μ and the internal pressure. A plot of W vs. shear modulus shows a relation which can be approximated by the following straight line (where W is in electronvolts and μ in gigapascals): W = 0.017 μ + 1.3 Using the relationship between the shear modulus and the pressure, it is thus possible to relate W to the pressure.

Comparison of some ambient aerosol samplers in combination with PIXE analysis

AbstractPIXE (particle induced x‐ray emission) analysis of aerosols has been applied to four different samplers to determine sample thickness corrections, detection limits and required sampling times in different environments. The samplers (two total filter samplers, a two stage filter sampler and a cascade impactor) were used with filters made by Ghia, Millipore, Nucleopore and backings of polystyrene film, respectively. The calculations were based on the accumulation mode aerosol (particles in the 0.05–2μm diameter range) composition. Sampling times (resulting in detection limits 10 times lower than assumed aerosol concentrations) ranged from a quarter of an hour in urban, to a quarter of a day in rural and to two weeks in remote environments. These sampling times are calculated with the requirement that at least one element representing each of the following sources was detected: fossil fuel combustion (S, V and Ni), leaded petrol combustion (Br and Pb) and general industrial activities (Cr, Cu and Zn). Generally the two stage filter sampler employed with Nuclepore filters yielded the highest time resolution when specific flow rate, thickness and substrate impurities were taken into consideration. Thickness corrections based on a proton energy of 2.55 MeV and typical ambient urban and rural aerosol matrices show that elements of low atomic number such as P, S and Cl, where the x‐ray self absorption effect is most important, require a 10–20% correction with a uniform deposit thickness of about 0.5 mg cm−2 and a non‐nuniform (conical) deposit thickness of about 1 mg cm−2. For elements of higher atomic number than vanadium (K x‐rays) the proton energy loss correction dominates. Sampling times resulting in the above mentioned deposit thicknesses were shortest for the cascade impactor while the Millipore and Nuclepore filter samplers were least critical in this respect.

The influence of secondary fluorescence from elements adjacent to the microbeam spot on local concentration determination with PIXE

In position dependent PIXE analyses with microbeams secondary fluorescence may induce X-ray emission from elements in the micrometer-range vicinity of the beam focus spot. To study this effect in a simplified geometry, CuAu layer targets have been prepared. This material combination enables iterative electroplating for easy preparation of varying layer thickness with plane borders between the two materials and gives simultaneously sufficient secondary fluorescence. The proton beam spot of dimensions 6 × 0.75 μm 2 is swept across the polished end face of the layer sandwich and the Cu and Au X-ray intensities are measured as a function of the distance x from the Cu-layer and of the proton energy E p. For proton energies between 1 and 3 MeV the decrease of the copper K α X-ray intensity outside the Cu-layer may be described by an exponential function I = I 0 cE p exp(− αx) , with α = 0.255 μm −1 and c = 0.0272 MeV −1.

Lattice Location of Si and Al Dissolved in Cr by Proton Channeling and Induced X-Ray Emission

Direct determination of the lattice location of Si and Al in Cr–2.3 a/o Si and Cr–1.4 a/o Al crystals has been made by measurirg backscattered proton and X-ray emission. Both yields along some axial and planar directions show channeling dips which coincide almost pith each other. It is concluded that Si and Al atoms occupy the substitutional sites in Cr at room temperature.

Measurement of the thickness of thin layers by proton- induced X-ray emission

The thickness of copper layers (5–200 nm) was measured from the Cu L X-ray excitation of the thin layers by bombardment with protons of energy 280 keV. The method was based on a comparison of the expected X-ray yield (calculated from thick target yield measurements) with the measured yield at the thin layer. The absolute accuracy achieved was better than ten per cent. The thickness distribution of the extended evaporated layers shows a cos 6( r h ) dependence. The results demonstrate that it is difficult to produce layers of known thickness controlled only by the quartz oscillation method because the steam direction from a boat-like evaporation source is uncertain.