Measurement Of Sr Research Articles

Broadband cavity-enhanced optical flux monitoring

This work describes a new type of sensor for growth process monitoring named broadband cavity-enhanced optical flux monitoring sensor (BBCE-OFM). Like existing optical flux monitoring (OFM) solutions, it relies on absorption spectroscopy. However, the implementation of an optical cavity reduces the measurement uncertainty, enabling efficient operation even at very low growth rates. Using the BBCE-OFM sensor mounted in our solid-source oxide molecular beam epitaxy reactor, we achieved an uncertainty of ±2% on the measurement of Sr and Ti growth rates in SrTiO3 at around 1 Ml/min, to be compared to the ±16% obtained in the same conditions using a conventional OFM setup. Furthermore, our sensor architecture, based on an echelle monochromator and LEDs replacing the hollow cathode lamps used in standard OFM sensors, is more robust against drift.

Line spectroscopic reflectometry for rapid and large-area thickness measurement.

Thickness measurements in the range of 0.1-1 mm over large optically transparent layers are essential in various manufacturing applications. However, existing non-contact measurement methods, which typically measure a single point or a few points at a time, fall short in their suitability for inline area measurement. Here, we introduce line spectroscopic reflectometry (LSR), an approach that extends the point measurement of traditional SR to line measurement, enabling rapid thickness measurement over large areas. By combining line beam illumination and line spectroscopy, LSR can measure 2048 points simultaneously, thereby boosting the measurement speed by two thousand times. We detail the measurement principle and the optical design in the near-infrared regime, and demonstrate thickness measurements of single-layered and double-layered samples over a measurement line length of up to 68 mm. Furthermore, we showcase the inline area measurement capability of LSR through one-dimensional sample scanning, with measurement rates limited only by camera readout rates.

Urine strontium-90 (Sr-90) manual and automated pre-analytical separation followed by liquid scintillation counting.

Responding to a radiological or nuclear incident may require assessing tens to hundreds of thousands of people for possible radionuclide contamination. The measurement of radioactive Sr is important because of its impact on people's health. The existing analytical method for urine Sr-90 analysis using crown ethers is laborious and involves possible exposure to concentrated acids; therefore, this work is devoted to the development of the automated Sr-90 separation process, which became possible with the prepFast pre-analytical system (Elemental Scientific, Inc).

Advanced Satellite-Based Frequency Transfer at the 10-16 Level.

Advanced satellite-based frequency transfers by two-way carrier-phase (TWCP) and integer precise point positioning have been performed between the National Institute of Information and Communications Technology and Korea Research Institute of Standards and Science. We confirm that the disagreement between them is less than at an averaging time of several days. In addition, an overseas frequency ratio measurement of Sr and Yb optical lattice clocks was directly performed by TWCP. We achieved an uncertainty at the mid-10-16 level after a total measurement time of 12 h. The frequency ratio was consistent with the recently reported values within the uncertainty.

Analysis of contaminated nuclear plant steel by laser-induced breakdown spectroscopy

Laser Induced Breakdown Spectroscopy (LIBS) has the potential to allow direct, standoff measurement of contaminants on nuclear plant. Here, LIBS is evaluated as an analytical tool for measurement of Sr and Cs contamination on type 304 stainless steel surfaces. Samples were reacted in model acidic (PUREX reprocessing) and alkaline (spent fuel ponds) Sr and Cs bearing liquors, with LIBS multi-pulse ablation also explored to measure contaminant penetration. The Sr II (407.77nm) and Cs I (894.35nm) emission lines could be separated from the bulk emission spectra, though only Sr could be reliably detected at surface loadings >0.5mgcm−2. Depth profiling showed decay of the Sr signal with time, but importantly, elemental analysis indicated that material expelled from LIBS craters is redistributed and may interfere in later laser shot analyses.

Spectroscopic study of the elusive globular cluster ESO452-SC11 and its surroundings

Globular clusters (GCs) are amongst the oldest objects in the Galaxy and play a pivotal role in deciphering its early history. We present the first spectroscopic study of the GC ESO452-SC11 using the AAOmega spectrograph at medium resolution. Given the sparsity of this object and high degree of foreground contamination due to its location toward the bulge, few details are known for this cluster: there is no consensus of its age, metallicity, or its association with the disk or bulge. We identify 5 members based on radial velocity, metallicity, and position within the GC. Using spectral synthesis, accurate abundances of Fe and several $\alpha$-, Fe-peak, neutron-capture elements (Si,Ca,Ti,Cr,Co,Ni,Sr,Eu) were measured. Two of the 5 cluster candidates are likely non-members, as they have deviant Fe abundances and [$\alpha$/Fe] ratios. The mean radial velocity is 19$\pm$2 km s$^{-1}$ with a low dispersion of 2.8$\pm$3.4 km s$^{-1}$, in line with its low mass. The mean Fe-abundance from spectral fitting is $-0.88\pm0.03$, with a spread driven by observational errors. The $\alpha$-elements of the GC candidates are marginally lower than expected for the bulge at similar metallicities. As spectra of hundreds of stars were collected in a 2 degree field around ESO452-SC11, detailed abundances in the surrounding field were measured. Most non-members have higher [$\alpha$/Fe] ratios, typical of the nearby bulge population. Stars with measured Fe-peak abundances show a large scatter around Solar values, though with large uncertainties. Our study provides the first systematic measurement of Sr in a Galactic bulge GC. The Eu and Sr abundances of the GC candidates are consistent with a disk or bulge association. Our calculations place ESO452 on an elliptical orbit in the central 3 kpc of the bulge. We find no evidence of extratidal stars in our data. (Abridged)

Can field portable X-ray fluorescence (pXRF) produce high quality data for application in environmental contamination research?

This research evaluates the analytical capabilities of a field portable X-ray fluorescence spectrometer (pXRF) for the measurement of contaminated soil samples using a matrix-matched calibration. The calibrated pXRF generated exceptional data quality from the measurement of ten soil reference materials. Elemental recoveries improved for all 11 elements post-calibration with reduced measurement variation and detection limits in most cases. Measurement repeatability of reference values ranged between 0.2 and 10% relative standard deviation, while the majority (82%) of reference recoveries were between 90 and 110%. Definitive data quality, the highest of the US EPA's three level quality ranking, was achieved for 15 of 19 elemental datasets. Measurement comparability against inductively coupled plasma atomic emission spectrometry (ICP-AES) values was excellent for most elements (e.g, r2 0.999 for Mn and Pb, r2 > 0.995 for Cu, Zn and Cd). Parallel measurement of reference materials revealed ICP-AES and ICP-MS measured Ti and Cr poorly when compared to pXRF. Individual recoveries of soil reference materials by both ICP-AES and pXRF showed that pXRF was equivalent to or better than ICP-AES values for all but two elements (Ni, As). This study demonstrates pXRF as a suitable alternative to ICP-AES analysis in the measurement of Ti, Cr, Mn, Fe, Cu, Zn, Sr, Cd, and Pb in metal-contaminated soils. Where funds are limited, pXRF provides a low-cost, high quality solution to increasing sample density for a more complete geochemical investigation.

Measurement of 90Sr in contaminated Fukushima soils using liquid scintillation counter.

A method based on liquid scintillation counting system has been developed for the measurement of (90)Sr in Fukushima soil samples due to contamination of (134)Cs and (137)Cs. Three soil samples were collected within 30 km radius from the Fukushima Daiichi Nuclear Power Plant (FDNPP). Activity concentration of (134)Cs and (137)Cs were measured using a gamma spectroscopy system with high-purity germanium detector. (90)Sr contamination is little elevated but comparable with the background contamination level that originated from atmospheric nuclear weapon tests, whereas radiocesium contamination has increased significantly. Activity concentration of (90)Sr in the soil samples varied in the range of 10.4±0.6-22.0±1.2 Bq kg(-1). Activity concentrations of (134)Cs and (137)Cs in the soil samples were in the range of 28.2±0.2-56.3±0.2 kBq kg(-1) and 35.2±0.1-70.2±0.2 kBq kg(-1), respectively (reference date for decay correction is 1 December 2011).

Solution chemistry study of radioactive Sr on Fukushima Daiichi NPS site

For the better understanding of chemical behavior of Sr-90 released from the damaged reactor cores of Fukushima Daiichi nuclear power station into the seawater system, the dissolution behavior of Sr(II) to the mixed seawater was experimentally investigated by the solubility measurement of Sr(II) under several solution conditions (mixing degree of seawater, pH, strontium concentration and temperature) and the microscopic analysis of the formed solid phase. The obtained results of the experiment were compared with thermodynamic equilibrium calculations for an interpretation of chemistry of Sr(II) in the targeted solution system. It was revealed that the Sr solubility became higher than the reported value in generic seawater system, while the solubility limiting solid was identified as SrSO4 which corresponded with the result of equilibrium calculation. Furthermore, under the unsaturated condition, about 6% of Sr(II) interacted with natural nano-size colloids existing in the Fukushima seawater and was captured by 3 kDa filter.

Separation and Isotopic Measurement of Sr in Tooth Samples Using Selective Specific Resins

Separation and Isotopic Measurement of Sr in Tooth Samples Using Selective Specific Resins

Effect of SR Manipulation on Conduit Artery Dilation in Humans

The impact of manipulating shear stress on conduit artery vasodilation has not been comprehensively described in vivo. We hypothesized that manipulation of SR through the brachial and radial arteries would be associated with corresponding changes in diameter. We performed a series of studies involving the following: (1) leg cycle exercise at increasing intensities (≈70 and 85% maximum heart rate [HRmax]) with simultaneous bilateral measurement of SR in the radial arteries; (2) leg cycle exercise for 30 minutes at 80% HRmax with simultaneous bilateral measurement of velocity and diameter in the brachial arteries; and (3) bilateral forearm heating for 30 minutes with simultaneous bilateral measurement of brachial artery diameter and blood velocity. Cycling and forearm heating interventions were performed in the presence of unilateral cuff inflation throughout the experiment, or starting during the intervention (15 minutes), to manipulate SR responses. Cuff placement was associated with lower radial artery SR responses (cuffed versus uncuffed, 248±49 versus 349±105 L/s 85% HRmax; P<0.01), and diameter responses were similarly attenuated (2.45±0.30 versus 2.78±0.20 mm 85% HRmax; P<0.05). Exercise performed at 80% HRmax in the presence of unilateral cuff inflation also reduced brachial artery SR (cuffed versus uncuffed; 258±107 versus 454±157 L/s; P<0.01) and diameter (3.96±0.39 versus 4.20±0.45 mm). Finally, cuff inflation decreased the impact of forearm heating on brachial SR (cuffed versus uncuffed; 262±97 versus 440±106 L/s; P<0.01) and diameter (4.35±0.54 versus 4.87±0.47 mm; P<0.05). Similar significant differences between the cuffed and uncuffed limbs in SR and diameter were observed when cuff inflation occurred during exercise or heating. Our findings strongly implicate SR as an important stimulus to increase conduit artery diameter in humans.

Multiple linear regression and on-line ion exchange chromatography for alternative Rb–Sr and Nd–Sm MC-ICP-MS isotopic measurements

A mathematical procedure of multiple linear regression in combination with on-line liquid chromatography was applied for the measurement of Sr and Nd isotope ratios by multicollector ICP-MS in the presence of isobaric isotopes. The separation of Rb and Sr and the separation of Nd and Sm were accomplished by ion exchange chromatography with large volume injection. This mode of injection allowed wide flat-topped chromatographic peaks to be obtained while maintaining chromatographic resolution and avoiding sample dilution. The application of the multiple linear regression procedure to the raw chromatographic data allowed the determination of the isotope ratios of Sr or Nd without interferences from isobaric isotopes. For Sr measurements, the raw 87Sr/86Sr isotope ratio precision (0.006 to 0.010%) was similar to that of continuous sample introduction (ca. 0.003%) at the same concentration level (50 ng g−1). The mathematical procedure was first evaluated for the cation exchange separation of Rb and Sr. Strontium isotope ratios, obtained using NIST SRM 987, were in agreement with the certified values (bias ca. 0.01%). For the case of Nd and Sm, their chromatographic separation was accomplished by anion exchange using EDTA as mobile phase. Neodymium eluted at 12.8 minutes while samarium eluted at 17.5 minutes, showing flat-topped chromatographic peaks and maintaining baseline neodymium–samarium separation. Precise neodymium and samarium isotope ratios suitable for Nd–Sm dating could be measured by MC-ICP-MS using the proposed multiple linear regression procedure using only one cup configuration.

A new method for determining the efficiency of large-area beta sources constructed from anodized aluminum foils

A new method has been developed for determining the efficiency of large-area beta sources in anodized aluminum foils using transmission measurements. The method was applied to the efficiency measurement of a (90)Sr-(90)Y large-area reference source. Measurement results show that the method can provide efficiency values for (90)Sr-(90)Y reference sources with standard uncertainties smaller than 2.9%, which are far below the limit of 10% required by ISO 8769.

Electrical and Magnetic Properties of ${\rm Sr}({\rm Ru},{\rm Cr}){\rm O}_{3}$ Thin Films

Cr-doped SrRuO3 (SRCO) thin films were grown on an SrTiO3 (STO) (001) substrate using a pulsed laser deposition method in order to study the effects of the Cr doping. Measurements of the out-of-plane lattice constant and the electrical and magnetic properties indicate that Cr is incorporated into the B-site of the SRO lattice. Magnetic hysteresis measurements reveal a ferromagnetic nature with a saturation magnetization of about 0.75 ?B/Ru. The magnetization measurement of Sr(Ru0.9Cr0.1)O3 showed a ferromagnetic transition temperature T C = 165 K. This T C value is about 13 K higher than that reported for SrRuO3 thin films. The T C enhancement due to Cr doping in SrRuO3 thin film was less than that observed for the bulk sample. Electrical resistivity measurements of the SRCO thin films reveal metallic behavior, with a much larger residual resistivity of ~260 ?? cm compared to 26 ?? cm for SrRuO3 thin films.

Measurement of specific airway resistance decreased the risk of delay in asthma diagnosis in children

Factors that facilitate the asthma diagnosis in children are still being investigated. We attempted to assess the duration of a delay in asthma diagnosis in children, and we examined the previously identified risk factors of its occurrence together with the pulmonary function test results such as spirometry and specific airway resistance (sR(aw)) and sought to determine how the measurement of sR(aw) contributes to asthma diagnosis in children. This study was a part of the Asthma Prevention Study in Poland, which focused on increasing early detection of asthma in a community-based cohort. Data were collected using a questionnaire during regular doctor visits. Childrens' medical documentation from the time period between birth and the visit was analyzed. Participants with the duration of an undiagnosed asthma above the upper quartile range of this variable were defined as having a delayed asthma diagnosis. The independent risk factors of the delayed asthma diagnosis included the absence of atopy, allergic rhinitis symptoms, asthma/allergy in a family, and living in the single-parent families. The whole-body plethysmography performed simultaneously with the spirometry revealed the underestimation of reversibility of bronchial obstruction in 16.4% of participants. This underestimation of reversibility of bronchial obstruction was the only modifiable, independent risk factor of the delayed asthma diagnosis in children. Measurement of sR(aw) contributes significantly to asthma diagnosis in children at risk of the delayed asthma diagnosis.

Enhanced methods for assessment of the trace element composition of Iron Age bone

Modern, ultra-trace, analytical methods, coupled with magnetic sector ICP-MS (HR-ICP-MS), were applied to the determination of a large suite of major and trace elements in Iron Age bones. The high sensitivity and un-paralleled signal-to-noise characteristics of HR-ICP-MS enabled the accurate measurement of Ag, Al, As, Ba, Ca, Cd, Ce, Co, Cr, Cu, Fe, La, Li, Mg, Mn, Ni, P, Pb, Pt, Rb, Sr, U, V, and Zn in small bone sections (< 75 mg). Critically, the HR-ICP-MS effectively addressed molecular interferences, which would likely have compromised data generated with quadrupole-based ICP-MS instruments. Contamination and diagenetic alteration of ancient bone are grave concerns, which if not properly addressed, may result in serious misinterpretation of data from bone archives. Analytical procedures and several chemical and statistical methods (Principal Components Analysis — PCA) were studied to assess their utility in identifying and correcting bone contamination and diagenetic alteration. Uncertainties in bone (femur) sampling were characterized for each element and longitudinal variation was found to be the dominant source of sampling variability. However the longitudinal variation in most trace elements levels was relatively modest, ranging between 9 and 17% RSD. Bone surface contamination was evaluated using sequential acid leaching. Calcium-normalized metal levels in brief, timed, dilute nitric acid leaches were compared with similarly normalized interior core metal levels to assess the degree of surface enrichment. A select group of metals (Mn, Co, Ni, Ag, Cd, and Pt) were observed to be enriched by up to a factor of 10 in the bone surface, indicating that that these elements may have a higher contamination component. However, the results of sequential acid leaching experiments indicated that the single acid leaching step was effective in removing most surface-enriched contaminants. While the leaching protocol was effective in removing contaminants associated with the bone surface, there remained potentially significant residual levels of soil-sourced contaminant tracers within the leached bone. To address this issue a mathematical procedure, based on metal/aluminum ratios, was developed to correct—for the soil—contaminant metal pools. Soil correction fractions for the primary anthropogenically mobilized metals evaluated were greatest for Pb (13.6%) followed by As (4.4%), Ag (3.9%), and Cd (0.94%). Although median soil corrections were typically low, many samples did require a much larger correction, thus both bone cleaning and soil corrections may be necessary to realize accurate endogenous bone elemental data. The results of the PCA analysis were remarkably consistent with outcomes from the chemical and elemental ratio protocols evaluated in the study, and suggest that loadings on certain factors will be helpful in screening for soil-biased samples and in identifying diagenetically altered bone. Application of these contamination evaluation and correction tools was made possible by the high-quality, multi-element, datasets produced by HR-ICP-MS. Large variations in bone core concentrations between the 80 Iron Age specimens examined were observed for all the primary trace elements and in many of the supporting elements, even after correction for major contaminant components.

Incremental Value of Strain Rate Analysis as an Adjunct to Wall-Motion Scoring for Assessment of Myocardial Viability by Dobutamine Echocardiography

Assessment of myocardial viability based on wall-motion scoring (WMS) during dobutamine echocardiography (DbE) is difficult and subjective. Strain-rate imaging (SRI) is quantitative, but its incremental value over WMS for prediction of functional recovery after revascularization is unclear. DbE and SRI were performed in 55 stable patients (mean age, 64+/-10 years; mean ejection fraction, 36+/-8%) with previous myocardial infarction. Viability was predicted by WMS if function augmented during low-dose DbE. SR, end-systolic strain (ESS), postsystolic strain (PSS), and timing parameters were analyzed at rest and with low-dose DbE in abnormal segments. Regional and global functional recovery was defined by side-by-side comparison of echocardiographic images before and 9 months after revascularization. Of 369 segments with abnormal resting function, 146 showed regional recovery. Compared with segments showing functional recovery, those that failed to recover had lower low-dose DbE SR, SR increment (DeltaSR), ESS, and ESS increment (DeltaESS) (each P<0.005). After optimal cutoffs for the strain parameters were defined, the sensitivity of low-dose DbE SR (78%, P=0.3), DeltaSR (80%, P=0.1), ESS (75%, P=0.6), and DeltaESS (74%, P=0.8) was better though not significantly different from WMS (73%). The specificity of WMS (77%) was similar to the SRI parameters. Combination of WMS and SRI parameters augmented the sensitivity for prediction of functional recovery above WMS alone (82% versus 73%, P=0.015; area under the curve=0.88 versus 0.73, P<0.001), although specificities were comparable (80% versus 77%, P=0.2). The measurement of low-dose DbE SR and DeltaSR is feasible, and their combination with WMS assessment improves the sensitivity of viability assessment with DbE.

Full polarization measurement of SR emitted from twin helical undulators with use of Sc/Cr multilayers at near 400 eV

We carried out the full polarization measurements on highly circularly polarized light in soft X-ray region. The measurements were performed on synchrotron radiation of near 400 eV emitted from twin helical undulators at BL25SU in the SPring-8. All parameters of polarization state of the light were determined with a phase shifting transmission multilayer and a polarizing reflection multilayer. The phase shifter was a newly developed Sc/Cr multilayer and was evaluated as a quarter-wave plate. The results of full polarization measurement indicated that the twin undulators produced symmetrically circularly polarized light.

Precise determination of Rb, Sr, Ba, and Pb in geological materials by isotope dilution and ICP-quadrupole mass spectrometry following selective separation of the analytes

A new method was developed for the high precision measurement of Rb, Sr, Ba, and Pb concentrations in silicate rocks. This method is based on the combined use of isotope dilution and ICP quadrupole mass spectrometry, with matrix element removal. The concomitant separation of the analytes is achieved by extraction chromatography (Ba, Sr, Pb) and inorganic cation exchange chromatography (Rb), on two small tandem columns filled with 0.1 ml of “Sr resin” and 1 ml of zirconium (or titanium) phosphate, respectively. Compared to previous separation schemes based on cation- and anion-exchange, this method allows the rapid, concomitant isolation of four trace elements of great interest in geochemistry, with a greatly reduced volume of reagents. The capabilities of the method in terms of precision (equal to or better than 1% RSD) and accuracy are demonstrated by duplicate analyses of four international reference materials (BIR-1, BHVO-1, AGV-1 and RGM-1, from the US Geological Survey) representative of various silicate rock bulk compositions and spanning a large range (0.2–1000 µg g−1) of analyte concentrations.

Determination of High Field Strength Elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g−1 Levels in Geological Reference Materials by Magnetic Sector ICP‐MS after HF/HClO4 High Pressure Digestion

Six low abundance rock reference materials (basalt BIR‐1, dunite DTS‐1, dolerite DNC‐1, peridotite PCC‐1, serpentine UB‐N and basalt TAFAHI) have been analysed for high field strength elements (Zr, Nb, Hf, Ta, Th and U), Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g−1 levels (in rock) by magnetic sector inductively coupled plasma‐mass spectrometry after HF/HClO4 high pressure decomposition. The adopted method uses only indium as an internal standard. Detection limits were found to be in the range of 0.08 to 16.2 pg ml−1 in solution (equivalent to 0.08 to 16.2 ng g−1 in rock). Our data for high field strength elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi for the six selected low abundance geological reference materials show general agreement with previously published data. Our Ta values in DTS‐1 and PCC‐1 (1.3 and 0.5 ng g−1) are lower than in previously published studies, providing smooth primitive mantle distribution patterns. Lower values were also found for Tl in BIR‐1, DTS‐1 and PCC‐1 (2, 0.4 and 0.8 ng g−1). Compared with quadrupole ICP‐MS studies, the proposed magnetic sector ICP‐MS method can generally provide better detection limits, so that the measurement of high field strength elements, Rb, Sr, Mo, Sb, Cs, Tl and Bi at ng g−1 levels can be achieved without pre‐concentration, ion exchange separation or other specialised techniques.