Measurement Of Te Research Articles

Determination of ultra-trace Te species in open ocean waters based on Mg(OH)2 coprecipitation, anion exchange resin column separation and inductively coupled plasma sector-field mass spectrometry using a 125Te-enriched isotope spike

We present a method for the determination of ultra-trace Te species (Te(IV) and Te(VI)) in open ocean waters. The proposed method is based on Mg(OH)2 coprecipitation, anion exchange resin column separation and inductively coupled plasma sector-field mass spectrometry (ICPSFMS) using a 125Te-enriched isotope spike. The largest advantage of the method is that the use of the spike allows accurate and precise determination when it combines with either isotope dilution or recovery correction. Tellurium-IV and VI are preconcentrated in a Mg(OH)2 precipitate and separated mutually by an anion exchange resin column. Te(IV) is retained to the column, while Te(VI) passing through the column is recovered by a subsequent column procedure after reduction of Te(VI) to Te(IV). Te(IV) is successfully eluted with a small amount of 0.01 M HCl. The additional merit of using this eluent is elimination of components that result in a memory effect during the measurement of Te(IV). Possible mass spectral interference on Te(IV) can be excluded by adjusting the mass window, and the Te(IV) concentrations determined by this approach agree well with those independently obtained by an oxidation procedure which removes the interference. The accuracy of the proposed method is verified with homemade standard seawater for which the measured concentrations agree well with results calculated from the value of the standard solution. Procedural blanks for Te(IV) and Te(VI) are 1.5 ± 0.9 pg kg−1 (n = 11) and 1.3 ± 0.9 pg kg−1 (n = 11) with corresponding overall detection limits of 3.0 pg kg−1 and 2.8 pg kg−1, respectively. Using the method, we have clarified vertical profiles of Te(IV) and Te(VI) in the subarctic western North Pacific for the first time.

Comparison of direct and indirect measures of transport efficiency in single particle inductively coupled plasma mass spectrometry

Accurate calibration of the fraction of introduced sample that is transported to the plasma, termed “transport efficiency” (TE), is required for particle sizing and number concentration determination by single particle inductively coupled plasma mass spectrometry (spICP-MS). In this study, we systematically compare three methods for the measurement of TE: the particle frequency (TEF), particle size (TES), and dynamic mass flow (DMF) methods. The TEF and TES methods provide a direct measure of TE but require a single nanoparticle (NP) reference material accurately value-assigned for particle size and number concentration of which few are available. The DMF method provides an indirect measure of TE and only requires measurement of the mass difference between the amount of sample solution introduced to the instrument and the amount of effluent exiting the spray chamber. Because the DMF method relies solely on mass measurements, it can provide an SI traceable measure of TE. However, the DMF method assumes that the mass difference represents the fraction of sample transported to the plasma. The veracity of the three approaches to account for TE is assessed using three different spray chamber types, i.e., Scott-type double pass, conical impact bead, and baffled cyclonic spray chambers operated at cooled (2 °C to 10 °C) and ambient temperature (19 °C to 21 °C) conditions equipped with different nebulizers on different ICP-MS platforms. When operating the spray chamber at ambient temperature, the DMF method yielded systematically higher measures of TE than the TEF and TES methods regardless of nebulizer type, spray chamber type, or ICP-MS platform. While better agreement between the three measures of TE was achieved when operating the spray chambers at 2 °C, DMF repeatability was poor. The deviation of particle number concentration, expressed as the median percent difference from the known value for various in-house value-assigned AuNP suspensions, ranged from – 18% to +8% (TEF) and from – 1% to – 70% (DMF) whereas the deviation for particle size ranged from – 3% to +1% (TES) and from – 4% to +44% (DMF) across all conditions. The large negative bias for counting and positive bias for sizing by the DMF method indicates an overestimation of TE which was traced to low recovery of the mass of effluent exiting the spray chamber. We found that the indirect measure of TE (DMF method) yielded acceptable results (within ±10% of known values for particle size and ± 20% of known values for number concentration) under select conditions (cyclonic spray chamber at 2 °C and Meinhard nebulizer), but the biases inherent to the DMF method are not fully understood for all studied conditions. Only the direct measures of TE (TEF and TES) yielded acceptable results across all use conditions.

A multi-channel x-ray temporal diagnostic for measurement of time-resolved electron temperature in cryogenic deuterium-tritium implosions at OMEGA.

Electron-temperature (Te) measurements in implosions provide valuable diagnostic information, as Te is unaffected by residual flows and other non-thermal effects unlike ion temperature inferred from a fusion product spectrum. In OMEGA cryogenic implosions, measurement of Te(t) can be used to investigate effects related to time-resolved hot-spot energy balance. The proposed diagnostic utilizes five fast-rise (∼15 ps) scintillator channels with distinct x-ray filtering. Titanium and stepped aluminum filtering were chosen to maximize detector sensitivity in the 10 keV-20 keV range, as it has been shown that these x rays have similar density and temperature weighting to the emitted deuterium-tritium fusion neutrons. Initial data collected using a prototype nosecone on the existing neutron temporal diagnostic demonstrate the validity of this diagnostic technique. The proposed system will be capable of measuring spatially integrated Te(t) with 20 ps time resolution and <10% uncertainty at peak emission in cryogenic DT implosions.

Microwave Measurement of a Compact Circular TE11Mode Coupler Loaded With Ridges

Design and microwave measurement of a linearly polarized circular TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> mode coupler are reported in this article. Based on our earlier designed input coupler with smooth wall, we proposed an improved structure with ridges loading resulting in a bandwidth up to 29.2%. Simulation results show the port reflection <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{11}$ </tex-math></inline-formula> less than −10 dB is in 7.9–10.6 GHz. And the split transmission <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${S}_{21}$ </tex-math></inline-formula> and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{31}$ </tex-math></inline-formula> are over −3.4 dB in this frequency range. According to the simulation results, the designed input coupler is fabricated and measured with the vector network analyzer. The measurement results show excellent performance, which is in good agreement with the simulation when the conductor loss is taken into consideration. In addition, an input coupler with a cutoff waveguide is designed to improve the efficiency of single-port transmission and the power utilization. Simulation results show the transmission efficiency of the single port achieves 91%.

Implementing time resolved electron temperature capability at the NIF using a streak camera.

A new capability at the National Ignition Facility (NIF) has been implemented to measure the temperature of x-ray emitting sources. Although it is designed primarily for Inertial Confinement Fusion (ICF), it can be used for any hot emitting source that is well modeled. The electron temperature (Te) of the hot spot within the core of imploded ICF capsules is an effective indicator of implosion performance. Currently, there are spatially and temporally integrated Te inferences using image plates. A temporally resolved measurement of Te will help elucidate the mechanisms for hot spot heating and cooling such as conduction to fuel, alpha-heating, mix, and radiative losses. To determine the temporally resolved Te of hot spots, specific filters are added to an existing x-ray streak camera "streaked polar instrumentation for diagnosing energetic radiation" to probe the emission spectrum during the x-ray burn history of implosions at the NIF. One of the difficulties in inferring the hot spot temperature is the attenuation of the emission due to opacity from the shell and fuel. Therefore, a series of increasingly thick titanium filters were implemented to isolate the emission in specific energy regions that are sensitive to temperatures above 3 keV while not significantly influenced by the shell/fuel attenuation. Additionally, a relatively thin zinc filter was used to measure the contribution of colder emission sources. Since the signal levels of the emission through the thicker filters are relatively poor, a dual slit (aperture) was designed to increase the detected signal at the higher end of the spectrum. Herein, the design of the filters and slit is described, an overview of the solving technique is provided, and the initial electron temperature results are reported.

Transient Elastography in Acute Cellular Rejection Following Liver Transplantation: Systematic Review

BackgroundTransient elastography (TE) is a noninvasive technique that measures liver stiffness. When an inflammatory process is present, this is shown by elevated levels of stiffness. Acute cellular rejection (ACR) is a consequence of an inflammatory response directed at endothelial and bile epithelial cells, and it is diagnosed through liver biopsy. This is a systematic review of the viability of TE in ACR following liver transplantation. MethodsThe Cochrane Library, Embase, and Medline PubMed databases were searched and updated to November 2016. The MESH terms used were “Liver Transplantation,” “Graft Rejection,” “Elasticity Imaging Techniques” (PubMed), and “Elastography” (Cochrane and Embase). ResultsSeventy studies were retrieved and selected using the PICO (patient, intervention, comparison or control, outcome) criteria. Three prospective studies were selected to meta-analysis and evaluation. A total of 33 patients with ACR were assessed with TE. One study showed a cutoff point of >7.9 kPa to define graft damage and <5.3 kPa to exclude graft damage (receiver operating characteristic 0.93; P < .001). Another study showed elevated levels of liver stiffness in ACR patients. However, in this study, no cutoff point for ACR was suggested. The final prospective study included 27 patients with ACR at liver biopsy. Cutoff points were defined as TE > 8.5 kPa, moderate to severe ACR, with a specificity of 100% and receiver operating characteristic curve of 0.924. The measurement of TE < 4.2 kPa excludes the possibility of any ACR (P = .02). ConclusionsTE may be an important tool for the severity of ACR in patients following liver transplantation. Further studies should be performed to better define the cutoff points and applicability of the exam.

Conceptual design of a polarimetric Thomson scattering diagnostic in ITER

Polarimetric Thomson scattering (TS) is a novel diagnostic technique proposed as an alternative to conventional (spectral) TS, for the measurement of the electron temperature Te and density ne in very hot fusion plasmas. Contrary to spectral TS, which is based on the reconstruction of the Doppler broadened frequency spectrum, in polarimetric TS Te is determined from the depolarization of the scattered radiation. The technique is suitable for ITER, where it is expected to be competitive with conventional spectral TS for measurements in the highest Te range, specially in backward-like conditions with the scattering angle 90° ≪ θ ⩽ 180°. In this paper we consider a hypothetical polarimetric TS diagnostic for ITER and evaluate its performance for the θ = 145° scattering condition typical of the core TS system and also for a different scattering geometry in which, using a tangential laser beam, the central region of the ITER plasma can be observed under a scattering angle θ ∼ 75°. In both cases we calculate the expected errors on the measured Te and ne that can be obtained with a simple, two-channel polarimeter, and taking into account that only a fraction of the TS wavelength spectrum is detected. In both cases the expected performances are compared with those of the conventional spectral core TS diagnostic to determine the plasma conditions in which the polarimetric technique is more advantageous. A measurement of the depolarization effect of the TS radiation using the JET High Resolution TS system of JET is also discussed.

Efficacy of external warming in attenuation of hypothermia in surgical patients.

Hypothermia in surgical patients can be the consequence of long duration of surgical intervention, general anaesthesia and low temperature in operating room. Postoperative hypothermia contributes to a number of postoperative complications such as arrhythmia, myocardial ischemia, hypertension, bleeding, wound infection, coagulopathy, and prolonged effect of muscle relaxants. External heating procedures are used to prevent this condition. The aim of this study was to evaluate the efficiency of external warming system in alleviation of cold stress and hypothermia in patients who underwent major surgical procedures. The study was conducted in the Military Medical Academy in Belgrade. A total of 30 patients of both genders underwent abdominal surgical procedures, randomly divided into two equal groups: the one was externally warmed using warm air mattress (W), while in the control group (C) surgical procedure was performed in regular conditions, without additional warming. Oesophageal temperature (Te) was used as indicator of changes in core temperature, during surgery and awakening postoperative period, and temperature of control sites on the right hand (Th) and the right foot (Tf) reflected the changes in skin temperatures during surgery. Te and skin temperatures were monitored during the intraoperative period, with continuous measurement of Te during the following 90 minutes of the postoperative period. Heart rates and blood pressures were monitored continuously during the intraoperative and awakening period. In the W group, the average Te, Tf and Th did not change significantly during the intraoperative as well as the postoperative period. In the controls, the average Te significantly decreased during the intraoperative period (from 35.61 ± 0.35 °C at 0 minute to 33.86 ± 0.51°C at 120th minute). Compared to the W group, Te in the C group was significantly lower in all the observed periods. Average values of Tf and Th significantly decreased in the C group (from 30.83 ± 1.85 at 20th minute to 29.0 ± 1.39°C at 120th minute, and from 32.75 ± 0.96 to 31.05 ± 1.09°C, respectively). The obtained results confirm that the external warming using warm air mattress was able to attenuate hypothermia, i.e. substantial decrease in core temperature, compared with the similar exposure to cold stress in the control group.

Improvement of the Harmonic Technique of Probe for Measurements of Electron Temperature and Ion Density

Conventional Langmuir probe techniques usually face the difficulty of being used in processing plasmas where dielectric compounds form, due to rapid failure by surface insulation. A solution to the problem, the so-called harmonic probe technique, had been proposed and shown effectiveness. In this study, the technique was investigated in detail by changing bias signal amplitudes V0, and evaluated its accuracy by comparing with the conventional Langmuir probe. It was found that the measured electron temperature Te increased with V0, but showing a relatively stable region when V0 > Te/e in which it was close to the true Te value. This is contrary to the general consideration that V0 should be smaller than Te/e for accurate measurement of Te. The phenomenon is interpreted by the non-negligible change of the ion current with V0 at low V0 values. On the other hand, the measured ni also increased with V0 due to the sheath expansion, and to improve the accuracy of ni it needs to linearly extrapolate the ni-V0 trend to V0=0. The results were applied to a diagnosis of the plasmas for chemical vapor deposition of diamond-like carbon thin films and the relationship between plasma parameters and films deposition rates was obtained.

Rotational Raman scattering as a source of polarized radiation for the calibration of polarization-based Thomson scattering

We discuss the use of rotational Raman scattering as a possible technique for the calibration of polarization based plasma diagnostics such as the polarimetric Thomson scattering (TS) systems proposed for the measurement of electron density ne and temperature Te in very hot fusion plasmas. First by using the Stokes vector formalism, we calculate the Mueller matrix of rotational Raman scattering from a diatomic gas (such as H2, D2 and N2) for a generic scattering angle and then we use it to describe in detail the polarization characteristics of the Raman radiation available in the typical conditions of a TS system in a fusion plasma. Then we consider the various experimental set-ups proposed for polarimetric TS and show that rotational Raman scattering can generate radiation with known intensity and polarization states that, although not equal to those of the TS radiation, are suitable for the calibration of polarimetric TS diagnostics. Finally we point out that in fusion experiments Raman polarimetry may be of interest also for the calibration of other polarization-based measurement systems, such as the motional Stark effect (MSE) diagnostics.

Conceptual design of a divertor Thomson scattering diagnostic for NSTX-U.

A conceptual design for a divertor Thomson scattering (DTS) diagnostic has been developed for the NSTX-U device to operate in parallel with the existing multipoint Thomson scattering system. Higher projected peak heat flux in NSTX-U will necessitate application of advanced magnetics geometries and divertor detachment. Interpretation and modeling of these divertor scenarios will depend heavily on local measurement of electron temperature, Te, and density, ne, which DTS provides in a passive manner. The DTS design for NSTX-U adopts major elements from the successful DIII-D DTS system including 7-channel polychromators measuring Te to 0.5 eV. If implemented on NSTX-U, the divertor TS system would provide an invaluable diagnostic for the boundary program to characterize the edge plasma.

Modelling of resistive sensor for high-power microwave pulse measurement of TE 01 wave in circular waveguide

The interaction of a semiconductor plate with TE 01 (H 01 ) wave in a circular waveguide has been investigated. A plate with contacts on its top and bottom serves as a sensing element (SE) for a resistive sensor (RS) based on the electron heating effect and devoted to high-power microwave pulse measurement. A three-dimensional finite-difference time-domain method was applied to simulate wave propagation within a circular waveguide segment with the SE placed on a wall of the waveguide. The electric field distribution, voltage standing wave ratio and the average electric field dependencies on frequency have been determined for several sets of dimensions and specific resistances of the SE. The influence of the resonance phenomena on the average electric field in the SE has been considered. As a result of our investigation, the optimal dimensions and specific resistance of the SE required to provide a flat frequency response of the RS were found.

Modelling of resistive sensor for high power microwave pulse measurement of TE11mode in circular waveguide

Interaction of a semiconductor plate with TE11 wave in a circular waveguide has been analysed for the purpose of optimizing a frequency response of a resistive sensor (RS). The performance of the RS is based on the electron heating effect and it is devoted to high power microwave pulse measurement. The semiconductor plate with contacts on its sidewalls serves as sensing element (SE) of the RS. A three-dimensional finite-difference time-domain method (FDTD) was applied to simulate wave propagation within a circular waveguide segment with the SE which is placed on a wall of the circular waveguide. The electric field distribution, voltage standing wave ratio (VSWR), and the average electric field dependences on frequency have been determined for several sets of dimensions and specific resistances of the SE. The parameters of the optimal SE were found. Keywords: electromagnetic wave, circular waveguide, mode TE11, semiconductor obstacle, resistive sensor

Sensitive Measurement of Se and Te in Cloud Water and Ambient Particulate Matter

ABSTRACT Analytical methods have been developed to measure low levels of trace elements (Te and Se) in cloud droplets and aerosol particulates. For water collected from cloud droplets, pneumatic nebulization coupled with inductively coupled plasma mass spectrometry yielded sufficient sensitivity to allow measurement of Se and Te after a 20-fold hotplate preconcentration. In cloud water samples collected on July 23, 1995, at Whiteface Mountain, New York, USA, Se and Te concentrations appeared to track one another, suggesting that Te could become a viable tracer element given that Se is already a proven tracer in the study of oxidation of SO2 into . For aerosol filter samples, a microwave digestion scheme was developed to dissolve the sample, resulting in highly diluted Se and Te concentrations, too low to be measured by pneumatic nebulization inductively coupled plasma mass spectrometry Hydride generation inductively coupled plasma mass spectrometry was used to improve the detection limits of Se and Te by a factor of 30. It enabled the detection of Se and Te in the low ng/L range in aqueous solution, or in the pg/m3 range in aerosol samples. An aerosol particulate standard (SRM1648, Urban Particulate Matter; NIST) and a sediment standard (GSD11; Institute of Geophysical and Geochemical Prospecting of China) were digested and analyzed to validate the methods.

How to Derotate the Cosmic Microwave Background Polarization

If the linear polarization of the cosmic microwave background is rotated in a frequency-independent manner as it propagates from the surface of last scatter, it may introduce a B-mode polarization. Here I show that measurement of higher-order TE, EE, EB, and TB correlations induced by this rotation can be used to reconstruct the rotation angle as a function of position on the sky. This technique can be used to distinguish primordial B modes from those induced by rotation. The effects of rotation can be distinguished geometrically from similar effects due to cosmic shear.

Langmuir probe characterization of laser ablation plasmas

For laser ablation plumes that are significantly ionized, Langmuir probes have proved to be a useful tool for measuring the plume shape, ion energy distribution, and electron temperature. Typically in laser ablation plasmas the flow velocity is supersonic, which complicates the interpretation of the current-voltage probe characteristic. In this paper we describe some recent developments on the application of Langmuir probes for laser ablation plume diagnosis. We have investigated the behavior of the probe when it is orientated perpendicular, and parallel, to the plasma flow, and show how an analytical model developed for plasma immersion ion implantation, can quantitatively describe the variation of the ion current with probe bias for the case when the plasma flow is along the probe surface. The ion signal recorded by a probe in the parallel position is proportional to the ion density and the square root of the bias voltage. It is shown that the current varies as mi−1/2 so that by comparing the ion signals from the parallel and perpendicular positions it is possible to estimate the mass of the ions detected. We have also determined the temporal variation of electron temperature. A planar probe oriented parallel to the plasma flow, where the ion current due to the plasma flow is eliminated, gives a more reliable measurement of Te (&amp;lt;0.6 eV). The measured Te is consistent with the measured ion current, which is dependent on Te when the time taken for an element of plasma to traverse the probe is longer than the time taken for the matrix ion sheath extraction phase.

On the determination of edge Ti profiles by a supersonic He beam in TJ-II

In the present work, a new diagnostic for the simultaneous measurement of ne, Te and Ti profiles at the edge of a fusion plasma is proposed and tested. First, the propagation of a supersonic He beam is self-consistently simulated from the electron parameter profiles reconstructed from the line ratio method. The radial profile of excited HeII ions, measured simultaneously with the HeI lines, is then compared with the simulated profile and the total effective ion loss rate from the observation volume is deduced, which is function of Ti and the local plasma parameters. The values so obtained are normalized to those from passive CX measurements (NPA). Steeper gradients and lower values are found in the Ti profile compared to those in the Te profiles. The implication of these findings in ion transport at the edge of the TJ-II stellarator is addressed.

Performance Characteristics of a Novel Tandem Mass Spectrometry Assay For Serum Testosterone

Commercial immunoassays for testosterone (Te) may give inaccurate results for samples from women and children, leading to misdiagnosis and inappropriate treatment. We developed a sensitive and specific tandem mass spectrometric assay for measurement of Te at the concentrations encountered in women and children. Te was extracted with methyl tert-butyl ether from 100 microL of serum or plasma, derivatized to form an oxime, and reextracted by solid-phase extraction. Instrumental analysis was performed on an API 4000 HPLC tandem mass spectrometer in the multiple-reaction monitoring (MRM) mode. The MRM transitions (m/z) were 304-->124 and 304-->112 for Te and 307-->124 and 307-->112 for d3-Te. Within- and between-run CVs were <12% and 7.9%, respectively. The limit of quantification was 0.0346 nmol/L (1 ng/dL). Reference intervals for sex hormone-binding globulin and total, free, and bioavailable Te were established for children of Tanner stages 1 through 5 and adult males and females. The sensitivity and specificity of the method are adequate for analysis of Te in samples from women and children. The method requires small sample volumes, has adequate precision, and is not subject to interferences.

Validation of 5 routine assays for serum free testosterone with a candidate reference measurement procedure based on ultrafiltration and isotope dilution–gas chromatography–mass spectrometry

Background/Method: The analytical validity of free testosterone (FTe) analog immunoassays is subject to much controversy. We revisited the validation of 4 analog assays and 1 FTe calculation procedure with a metrologically traceable reference measurement procedure (RMP) based on ultrafiltration and isotope dilution–mass spectrometry for direct measurement of Te in the ultrafiltrate. To this end, we performed split-sample measurements of 40 male sera. Results: Deming regression showed that 3 of the immunoassays had moderate to good correlation (0.8474 ≤ r ≤ 0.9241) with the RMP; however, the slope was markedly below 1. The FTe calculation procedure was in good agreement with this result. The Sy/ x values for all assays were higher than the combined imprecision values, which indicate their susceptibility to matrix-related effects. Conclusions: The study demonstrated substantial differences in analytical quality of FTe assays; however, the results suggested that after extending the validation with a larger variety of samples, recalibration of some analog assays might be worth further investigation.

Chemical Form of Precipitate by Coprecipitation with Palladium for Separation of Trace Elements in High-Purity Metals

The reductive coprecipitation with palladium has been reported for separation and pre-concentration of trace elements in high-purity metals. In order to evaluate the chemical forms of precipitate by this method, precipitates from acidic solution containing Se, Te, Au, Ag and Pd (only or mixture) were produced under the condition of quantitative precipitation and measured by X-ray diffraction and electron diffraction. The precipitates from solutions including single element were confirmed by X-ray diffraction or electron diffraction. In measurement of Te and Pd precipitate, X-ray diffraction peaks of each element were increase as leaving time lengthens. In measurement of Se precipitate, no X-ray diffraction patterns were found independent of leaving time in the acidic solution. But when leaving time was 24 h, electron diffraction spots of Se were found. The precipitates from solutions including mutual elements (mi xture of Pd and the other elements (Se, Te, Au and Ag)) were confirmed by X-ray diffraction or electron diffraction. In measurement of Pd-Au or Pd-Ag precipitate, these elements were respectively precipitated as elementary substance. However, in measurement of Pd-Se or Pd-Te precipitate, it was found that palladium selenide (Pd x Se y ) or palladium telluride (Pd x Te y ) was product.