Cadmium Ratio Research Articles

Efficient cadmium removal from aqueous solutions using a sample coal waste activated by rhamnolipid biosurfactant

A sample coal waste activated by rhamnolipid biosurfactants was used as an efficient adsorbent for the adsorption of cadmium from aqueous solution. The effects of three factors, namely, initial solution pH (3–11), absorbent to cadmium ratio (12.5–162.5) and contact time (3–31 h), on cadmium removal were studied and optimized using a central composite type response surface methodology. The two factors that play a key role in the adsorption process are pH and absorbent dosage. Optimum adsorption conditions achieved at pH 9, absorbent to cadmium ratio of 125 and equilibrium contact time of 10 h, resulted in more than 99% cadmium removal. Kinetic studies revealed that a maximum removal can be achieved before 10 min of adsorption process following a pseudo-second order model. The selectivity study in bimetal aqueous systems using copper, lead and zinc metals showed the adsorption order of Cu2+ > Cd2+ > Zn2+ > Pb2+. The cadmium adsorption on activated coal waste was also found to follows the Temkin isotherm model with a correlation coefficient of 92.43%.

Set-up of prompt gamma neutron activation analysis system at Kartini reactor

Setup and testing of prompt gamma neutron activation analysis (PGNAA) system by using neutron source from the radial beam-port of Kartini reactor have been done. The method used is an experimental characterization of neutron flux in the radial beam-port then setting up of PGNAA system and determination of elements in a bulk solution sample of salt (NaCl). The PGNAA system configuration consists of the collimator with L/D of 28.9 made from lead placed inside the beam-port, bulk sample with 20cm x 20cm x 43cm in dimension located at 30 cm from outer surface of the beam-port, and NaITl detector. The distance of sample to NaITl detector is 20 cm. The experimental test results show that the elements contained in the sample solution of salt can be detected well. The neutron flux in the outer surface of beam-port was measured using activation foil detector, the result was in the order of 106 n cm-2 s-1 with a cadmium ratio of 14.

Removal of Cadmium from Cobalt Sulfate by Solvent Extraction Using Cyanex 301

A variety of reagents, including P204, P507, and Cyanex 301, were used for extraction of cobalt and cadmium from cobalt sulfate solution. It was found that Cyanex 301 exhibited the best separation efficiency for cadmium and cobalt from solution containing 90 g L−1 Co and 3 g L−1. The effects of initial pH, extractant concentration, phase ratio, extraction time, and temperature on the cadmium and cobalt extraction ratios were examined. The results showed that the extraction ratios of cadmium and cobalt were 99.95% and 2.45% under the optimal conditions of pH 1.8, 10% Cyanex 301, O/A = 1:1, T = 25°C, and t = 10 min. The species of Cyanex 301 chelated with cadmium or cobalt were proposed to be Cd[Cyanex 301]2.5 and Co[Cyanex 301]2. The stripping ratios of cadmium and cobalt were 99.9% and 95% using 7 mol L−1 hydrochloric acid, respectively, indicating effective separation of cadmium from high-concentration cobalt sulfate solution.

Measurements of the thermal neutron cross-section and resonance integral for the 108 Pd(n,γ) 109 Pd reaction

Abstract The thermal neutron capture cross-section (σ0) and resonance integral (I0) of the 108Pd(n,γ)109Pd reaction have been measured relative to that of the monitor reaction 197Au(n,γ)198Au. The measurements were carried out using the neutron activation with the cadmium ratio method. Both the samples and monitors were irradiated with and without cadmium cover of 0.5 mm thickness. The induced activities of the reaction products were measured with a well calibrated HPGe γ-ray detector. In order to improve the accuracy of the results, the necessary corrections for the counting losses were made. The thermal neutron capture cross-section and resonance integral of the 108Pd(n,γ)109Pd reaction were determined to be σ0,Pd = 8.68 ± 0.41 barn and I0,Pd = 245.6 ± 24.8 barn, respectively. The obtained results are compared with literature values and discussed.

IMPROVEMENTS IN THE THERMAL NEUTRON CALIBRATION UNIT, TNF2, AT LNMRI/IRD.

The standard thermal neutron flux unit, TNF2, in the Brazilian National Ionizing Radiation Metrology Laboratory was rebuilt. Fluence is still achieved by moderating of four 241Am-Be sources with 0.6 TBq each. The facility was again simulated and redesigned with graphite core and paraffin added graphite blocks surrounding it. Simulations using the MCNPX code on different geometric arrangements of moderator materials and neutron sources were performed. The resulting neutron fluence quality in terms of intensity, spectrum and cadmium ratio was evaluated. After this step, the system was assembled based on the results obtained from the simulations and measurements were performed with equipment existing in LNMRI/IRD and by simulated equipment. This work focuses on the characterization of a central chamber point and external points around the TNF2 in terms of neutron spectrum, fluence and ambient dose equivalent, H*(10). This system was validated with spectra measurements, fluence and H*(10) to ensure traceability.

Development of neutron imaging beamline for NDT applications at Dhruva reactor, India

Thermal neutron imaging techniques such as radiography or tomography are very useful tool for various scientific investigations and industrial applications. Neutron radiography is complementary to X-ray radiography, as neutrons interact with nucleus as compared to X-ray interaction with orbital electrons. We present here design and development of a neutron imaging beamline at 100 MW Dhruva research reactor for neutron imaging applications such as radiography, tomography and phase contrast imaging. Combinations of sapphire and bismuth single crystals have been used as thermal neutron filter/gamma absorber at the input of a specially designed collimator to maximize thermal neutron to gamma ratio. The maximum beam size of neutrons has been restricted to ∼120 mm diameter at the sample position. A cadmium ratio of ∼250 with L∕D ratio of 160 and thermal neutron flux of ∼4×107 n/cm2 s at the sample position has been measured. In this paper, different aspects of the beamline design such as collimator, shielding, sample manipulator, digital imaging system are described. Nondestructive radiography/tomography experiments on hydrogen concentration in Zr-alloy, aluminium foam, ceramic metal seals etc. are also presented.

Study of the Radiation Resistance of Endohedral Fullerenes of Rare-Earth Elements and Their Water-Soluble Derivatives

Endohedral metallofullerenes Me@C2n (n = 30–50), their hydroxylated derivatives Me@C2n(OH)38–40 (Me = Tm, Ho, Eu, Sm, Co), and fullerenol С60(OH)38 have been synthesized The radiation resistance of these structures under irradiation in reactor by thermal and fast neutron fluxes in the fluence range of 1018–1019 cm–2 (cadmium ratio of ~10) has been analyzed. Endofullerenols are shown to be more stable in comparison with initial endohedral fullerenes; the molecules containing Eu and Sm (atoms characterized by the largest slow-neutron absorption cross section) turned out to be most stable. The mechanism of the formation of secondary Eu and Sm endofullerenols is discussed taking into account the neutron capture and emission of γ quanta by excited nuclei, which acquire the recoil energy.

Measurement of neutron energy spectrum at the radial channel No. 4 of the Dalat reactor.

IntroductionSeveral compositions of neutron filters have been installed at the channel No. 4 of the Dalat research reactor to produce quasi-monoenergetic neutron beams. However, this neutron facility has been proposed to enhance the quality of the experimental instruments, and to characterize the neutron spectrum parameters for new filtered neutron beams of 2 keV, 24 keV, 59 keV and 133 keV.Case descriptionIn order to meet the demand of neutron spectrum information for calculation and design of filtered neutron facilities at the Dalat nuclear research reactor (DNRR), the experimental determinations of neutron flux and energy spectrum, up to 8 MeV, has been performed at the inner entrance of the horizontal channel No. 4 from the core of DNRR. The Westcott neutron fluxes as well as the α-parameter that represents the deviation of epithermal neutron distribution from the 1/E law were measured by applying the cadmium ratio and the multi-foils activation methods. The fast neutron spectrum was measured based on the iterative adjustment procedure with threshold reactions.Discussion and evaluationA set of pure metal thin foils with the diameter of 1.27 cm and thickness of 0.125 mm were used as threshold detectors to measure the integrated fluxes, and a calculation procedure on iterative adjustment was implemented to derive the differential neutron energy spectrum from the integrated values.ConclusionsThe neutron fluxes and spectrum parameters were characterized with the measured values of 4.80 × 109, 1.98 × 107, 5.06 × 108 cm−2 s−1 and 0.0448 for the thermal, epithermal, fast neutron fluxes and the α-shape factor, respectively. The present result has been significantly applied to the input data for the Monte Carlo simulations in the developments of filtered mono-energetic neutron beam facility at the institute.

Thermal neutron radiative capture cross-section of 186W(n, γ)187W reaction

The thermal neutron radiative capture cross section for 186W(n, γ)187W reaction was measured by the activation method using the filtered neutron beam at the Dalat research reactor. An optimal composition of Si and Bi, in single crystal form, has been used as neutron filters to create the high-purity filtered neutron beam with Cadmium ratio of Rcd = 420 and peak energy En = 0.025 eV. The induced activities in the irradiated samples were measured by a high resolution HPGe digital gamma-ray spectrometer. The present result of cross section has been determined relatively to the reference value of the standard reaction 197Au(n, γ)198Au. The necessary correction factors for gamma-ray true coincidence summing, and thermal neutron self-shielding effects were taken into account in this experiment by Monte Carlo simulations.

Neutron spectrum measurements at a radial beam port of the NUR research reactor using a Bonner spheres spectrometer

This paper describes the measurement campaign held around the neutron radiography (NR) facility of the Algerian 1MW NUR research reactor.The main objective of this work is to characterize accurately the neutron beam provided at one of the radial channels of the NUR research reactor taking benefit of the acquired CRNA Bonner spheres spectrometer (BSS). The specific objective was to improve the image quality of the NR facility. The spectrometric system in use is based on a central spherical 3He thermal neutron proportional counter combined with high density polyethylene spheres of different diameters ranging from 3 to 12in. This counting system has good gamma ray discrimination and is able to cover an energy range from thermal to 20MeV. The measurements were performed at the sample distance of 0.6m from the beam port and at a height of 1.2m from the facility floor. During the BSS measurements, the reactor was operating at low power (100W) to avoid large dead times, pulse pileup and high level radiation exposures, in particular, during spheres handling.Thereafter, the neutron spectrum at the sample position was unfolded by means of GRAVEL and MAXED computer codes. The thermal, epithermal and fast neutron fluxes, the total neutron flux, the mean energy and the Cadmium ratio (RCd) were provided. A sensitivity analysis was performed taking into account various defaults spectra and ultimately a different response functions in the unfolding procedure. Overall, from the obtained results it reveals, unexpectedly, that the measured neutron spectrum at the sample position of the neutron radiography of the NUR reactor is being harder with a predominance of fast neutrons (>100keV) by about 60%. Finally, those results were compared to previous and more recent measurements obtained by activation foils detectors. The agreement was fairly good highlighting thereby the consistency of our findings.

Determination of effective resonance energy for the 193Ir(n,γ)194Ir reaction by the cadmium ratio method

In this work, the effective resonance energy, E¯r-value for the 193Ir(n,γ)194Ir reaction was measured using cadmium ratio method. A dual monitor (197Au–98Mo), which has convenient resonance properties, was employed for characterization of the irradiation sites. Then analytical grade iridium oxide samples diluted with CaCO3 to lower neutron self-shielding effect stacked in small cylindrical Teflon boxes were irradiated once with a 1mm thick Cd cylindrical box placed in a thermalized neutron field of an 241Am–Be neutron source then without it. The activities produced in samples during 193Ir(n,γ)194Ir reaction were measured using a p-type HPGe detector γ-ray spectrometer with a 44.8% relative efficiency. The correction factors for thermal, epithermal neutron self-shielding (Gth, Gepi), true coincidence summing (Fcoi) and gamma-ray self-absorption (Fs) effects were determined with appropriate approaches and programs. Thus, the experimental E¯r-value was determined to be 2.65±0.61eV for 193Ir target nuclide. The recent data for Q0 and FCd values for E¯r determination were based on k0-NAA online database. The present experimental E¯r value was calculated and compared with more recent values for Q0 and FCd for 193Ir. Additionally, the E¯r-values was theoretically calculated from the up-to-date resonance data obtained from ENDF/B VII library using two different approaches. Since there is no experimentally determined E¯r-value for the 193Ir isotope, the results are compared with the calculated ones given in the literature.

Detection of minor and trace elements in powdered milk

Passive gamma ray spectrometry and neutron capture prompt gamma activation analysis (PGAA) were used to investigate powdered cow's milk samples [termed optimal (1), optimal (2) and optimal (3)] collected from local markets in the city of Cairo, Egypt. Standard material with a total average activity of 0.830±0.2μCi and a certified reference material [IAEA (A-14)] were used to study the accuracy of a passive multi-gamma ray measurement method. Three powdered milk samples of the same geometry and volume were used in this analysis. The specific activity of 226Ra ranged from 24.5±2.1 to 114±1.2Bq/kg, 232Th from 8±1 to 14±1.2Bq/kg and 40K from 444±28 to 1826.1±3.1Bq/kg, all of which were higher than the activities corresponding to the United Nations Scientific Committee on the Effect of Atomic Radiation (UNSCEAR) (50, 50 and 500Bq/kg for 226Ra, 232Th and 40K, respectively). The average dose rate at 1cm for 40K ranged from 8.21E−02±0.12 to 3.3E−1±0.22mSv/h/cm. We also showed that 208Tl81, 212Pb82 and 212Bi83 should be considered products of thorium. k0-PGAA was carried out using an integrated and calibrated prompt gamma ray system with a neutron flux of 106n/cm2 per second. The thermal to epithermal neutron flux ratio (f) and cadmium ratio were measured using a thin gold foil technique (ration=160). Different Cl concentrations were prepared as standards for k0-PGAA. The elemental concentrations of Na, Mg, Al, Ca, Mn, Fe, Cu, Ga, Zn, As, Se, Cs, Cd, In, Th and I were measured in the three powdered milk samples. The mean±standard deviation ranges of the elements were as follows: Na=1069±49–1583±53ppm, Mg=347±13.64–385±16.71ppm, Al=45±1.30–72±2.40ppm, Fe=5500±110–7123±130ppm, Zn=107±3–123±6ppm, Ca=4200±72–5483±81ppm, Mn=1269±69–1784±72ppm, Pr=1.7±0.02–2.6±0.07ppm, Ga=265±5–293±8ppm, Cu=57±0.5–64±0.9ppm, In=1000± 38.64–1574±41.34ppm, Cd=6.1±2.71–12.6±4.11ppm, I=53±0.09–62±1.18ppm, Cs=4±1.56–11±4.22ppm, As=26±0.66–29±0.89ppm, Se=126±4.8–144±5.7ppm, Th=47±1.0–78±6.0ppm.

Zncds:Cu, Al, Cl: A Near Infra-Red Emissive Phosphor for Marking, Coding, and Identification

The availability of near-ultraviolet light and visible light emitting diodes in addition to infrared emitting systems has made the remote excitation of infrared emitting phosphors a practical possibility. Infrared emitting powder phosphors have the potential to meet marking and coding requirements, especially in low light and poor visibility. The advantages of IR emitting powder phosphors are:- 1) That they can easily be deposited by conventional techniques to form large areas, if required, either by simple settling techniques, or by inclusion in a binder suitable for screen or ink-jet printing (the binder must be transparent over the required spectral range). 2) Such deposited powder layers, depending on thickness and particle size etc., can be used in a transmission or reflective mode with suitable UV or visible excitation sources. The ease of fabrication and the wide excitation spectra efficiency of the material facilitate a wide range of potential applications, including the following as preliminary examples: a) For use in coding/marking systems as simple IR sensitive markers. b) For improved marking/detection in conjunction with night vision systems.1 It has been reported that increasing the cadmium concentration in Zn1-xCdxS solid solutions shifted the photoluminescence emission band to longer wavelength because the band gap energy (Eg) decreases with increasing cadmium concentration, from 3.91eV for ZnS to 2.58eV in CdS.2 Werring et al used Zn0.4Cd0.6S:Cu with an emission peak at ~900nm in order to match with the absorption peak of a silicon thyristor for use in an infrared switching device.3 Altering the zinc to cadmium ratio allows fine tuning of the wavelength of the photoluminescent emission band. The aim of this work was to shift the emission peak of the phosphor sufficiently far into the infra-red region so that visible light emission was minimised and the infra-red emission from the phosphor was clearly detectable by night vision systems. Zn1-xCdxS:Cu phosphors with higher cadmium concentrations higher than Zn0.4Cd0.6S:Cu were selected for study with the aim that the increased cadmium concentration would result in the emission band being moved sufficiently far into the near infrared region. Zn1-xCdxS:Cu0.03,Al0.03,Cl and Zn1-xCdxS:Cu0.03,Cl and (where x =0.5-0.9) phosphors were synthesized by an aqueous decomposition method. The photoluminescent (PL) excitation spectra, at 1000nm emission, of Zn1-xCdxS:Cu0.03,Al0.03,Cl (where x =0.5-0.9) phosphors are presented in Figure 1a, and the corresponding PL emission spectra in Figure 1b. For the excitation spectrum of each phosphor (Figure 1a) there was a broad peak at ~365nm, a more intense sharp peak between ~460-505nm which shifted to longer wavelengths with increasing cadmium concentration, and an intense very broad excitation band between ~520nm and ~645nm. The relatively strong excitation band at ~365nm facilitates the use of long wavelength UV lamps and UV emitting LEDs as backlights for the infrared emission panels and broad excitation in the blue region means that these IR emitting phosphors could also be excited by blue light emitting LEDs. Addition of aluminium ions as a co-dopant in these phosphors resulted in a blue shift in emission intensity (Figure 1b) compared to the corresponding Zn1-xCdxS:Cu0.03,Cl phosphors (Figure 1c). The shift to shorter wavelengths was ~70nm for Zn0.5Cd0.5S:Cu0.03,Al0.03,Cl but decreased in intensity with increasing cadmium concentration. The blue shift for Zn0.9Cd0.1S:Cu,Al,Cl was ~30nm. A comparison of the emission brightness of Zn1-xCdxS:Cu0.03,Al0.03,Cl and Zn1-xCdxS:Cu0.03,Cl (where x =0.5-0.9), is presented in Figure 1d. For the phosphors which did not include aluminium as a co-dopant, there was a small increase in emission intensity with increasing cadmium concentrations; this reached a plateau at the highest cadmium concentrations. In contrast, the presence of aluminium resulted in a significant increase in the PL emission intensity at the highest cadmium concentrations. The PL emission peak of Zn0.1Cd0.9S:Cu0.03,Al0.03,Cl was 219% more intense compared to that of Zn0.1Cd0.9S:Cu0.03,Cl. At the higher cadmium concentrations, PL emission which involved Al-Cu donor acceptor pairs resulted in significantly brighter PL emission compared to PL emission from Cl-Cu donor-acceptor pairs. Reference A. Vecht, J. Silver, R. Withnall, and G.R. Fern, DARPA Report, R+D 9350 EE01, (2004)S. Shionoya in Phosphor Handbook, 2nd ed., W.M. Yen, S. Shionoya, and H. Yamamoto, Editors, p256, CRC Press, Boca Raton (2007).N.J. Werring, A. Vecht, and J.W. Fletcher, Brit. J. Appl. Phys. (J. Phys. D), 2, 509-513, (1969). Figure 1. (a) PL excitation spectra, at 1000nm emission of Zn1-xCdxS:Cu0.03,Al0.03,Cl (where x =0.5-0.9) phosphors, (b) normalised PL emission spectra, under 580nm excitation, of Zn1-xCdxS:Cu0.03,Al0.03,Cl (where x =0.5-0.9) phosphors, (c) normalised PL emission spectra, under 580nm excitation, of Zn1-xCdxS:Cu0.03,Cl (where x =0.5-0.9) phosphors and (d) PL emission intensities of Zn1-xCdxS:Cu0.03,Cl phosphors (à) and Zn1-xCdxS:Cu0.03,Al0.03,Cl phosphors (ð) with increasing cadmium concentrations (x). Figure 1

Measured neutron flux parameters in the USGS TRIGA MARK I reactor

Using the Westcott convention, the Westcott flux, \( \varphi_{\text{w}} \); modified spectral index, \( r\sqrt {T_{n} /T_{0} } \); neutron temperature, Tn; and gold-based cadmium ratios were determined for various sampling positions in the U.S. Geological Survey (USGS) Training, Research, Isotopes, General Atomic (TRIGA) Mark I reactor. Westcott parameters were determined by a bare multi-monitor method. Thermal-neutron temperature measurements were made using lutetium foils. The differential neutron energy spectrum measurement was obtained using the computer iterative code SAND-II-SNL. Measurement of the neutron spectrum has resulted in a better knowledge of the reactor core and will improve predictive radioisotope production calculations necessary for neutron activation analysis and medical isotope production.

Evaluation of Cadmium Ratio and Foil Activation Measurements for a Beryllium-Reflected Assembly of U(93.15)O2 Fuel Rods (1.506-cm Triangular Pitch)

A series of small, compact critical assembly experiments was completed from 1962 to 1965 at Oak Ridge National Laboratory’s Critical Experiments Facility in support of the Medium-Power Reactor Experiments program. Initial experiments, performed in November and December 1962, consisted of a core of unmoderated stainless steel tubes surrounded by a graphite reflector. Later experiments included beryllium-reflected assemblies with the fuel in a 1.506-cm triangular lattice and in seven-tube clusters. Once the critical configurations had been achieved, various measurements of reactivity, relative axial and radial activation rates of 235U, and cadmium ratios were performed. The critical configurations, the cadmium ratio, and activation rate measurements for the beryllium-reflected 1.506-cm-array critical configuration have been evaluated and are described in this paper. It was found that these measurements are acceptable as benchmark experiments and have been included in the International Handbook of Evaluated Reactor Physics Benchmark Experiments and the International Handbook of Evaluated Criticality Safety Benchmark Experiments.

Characterization of neutron flux spectra in the irradiation sites of a 37 GBq 241Am-Be isotopic source

For the applicability of instrumental neutron activation analysis (NAA) technique, an irradiation unit with a 37GBq 241Am-Be neutron source was installed at Institute of Nuclear Sciences of Ankara University. Design and configuration properties of the irradiation unit are described. It has two different sample irradiation positions, one is called site #1 having a pneumatic sample transfer system and the other is site #2 having a location for manual use. In order to characterize neutron flux spectra in the irradiation sites, the measurement results were obtained for thermal (Фth) and epithermal neutron fluxes (Фepi), thermal to epithermal flux ratio (f) and epithermal spectrum shaping factors (α) by employing cadmium ratios of gold (Au) and molybdenum (Mo) monitors. The activities produced in these foils were measured by using a p-type, 44.8% relative efficiency HPGe well detector. For the measured γ-rays, self-absorption and true coincidence summing effects were taken into account. Additionally, thermal neutron self-shielding and resonance neutron self-shielding effects were taken into account in the measured results. For characterization of site #1, the required parameters were found to be Фth=(2.11±0.05)×103ncm−2s−1, Фepi=(3.32±0.17)×101ncm−2s−1, f=63.6±1.5, α=0.045±0.009, respectively. Similarly, those parameters were measured in site #2 as Фth=(1.49±0.04)×103ncm−2s−1, Фepi=(2.93±0.15)×101ncm−2s−1, f=50.9±1.3 and α=0.038±0.008. The results for f-values indicate that good thermalization of fast neutrons on the order of 98% was achieved in both sample irradiation sites. This is because an optimum combination of water and paraffin moderator is used in the present configuration. In addition, the shielding requirements are met by using natural boron oxide powder (5.5cm) and boron loaded paraffin layers against neutrons, and a 15cm thick lead bricks against gamma-rays from source and its surrounding materials.

Design and construction of a thermal neutron beam for BNCT at Tehran Research Reactor

An irradiation facility has been designed and constructed at Tehran Research Reactor (TRR) for the treatment of shallow tumors using Boron Neutron Capture Therapy (BNCT). TRR has a thermal column which is about 3m in length with a wide square cross section of 1.2×1.2m2. This facility is filled with removable graphite blocks. The aim of this work is to perform the necessary modifications in the thermal column structure to meet thermal BNCT beam criteria recommended by International Atomic Energy Agency. The main modifications consist of rearranging graphite blocks and reducing the gamma dose rate at the beam exit. Activation foils and TLD700 dosimeter have been used to measure in-air characteristics of the neutron beam. According to the measurements, a thermal flux is 5.6×108 (ncm−2s−1), a cadmium ratio is 186 for gold foils and a gamma dose rate is 0.57Gyh−1.

Low serum zinc is associated with elevated risk of cadmium nephrotoxicity

BackgroundDespite animal evidence suggests that zinc modulates cadmium nephrotoxicity, limited human data are available. ObjectiveTo test the hypothesis that low serum zinc concentrations may increase the risk of cadmium-mediated renal dysfunction in humans. MethodsData from 1545 subjects aged 20 or older in the National Health and Nutrition Examination Survey (NHANES), 2011–2012 were analyzed. Renal function was defined as impaired when estimated glomerular filtration rate (eGFR) fell below 60ml/min/1.73m2 and/or the urinary albumin-to-creatinine ratio surpassed 2.5 in men and 3.5mg/mmol in women. ResultsWithin the study cohort, 117 subjects had reduced eGFR and 214 had elevated urinary albumin. After adjusting for potential confounders, subjects with elevated blood cadmium (>0.53μg/L) were more likely to have a reduced eGFR (odds ratio [OR]=2.21, 95% confidence interval [CI]: 1.09–4.50) and a higher urinary albumin (OR=2.04, 95% CI: 1.13–3.69) than their low cadmium (<0.18μg/L) peers. In addition, for any given cadmium exposure, low serum zinc is associated with elevated risk of reduced eGFR (OR=3.38, 95% CI: 1.39–8.28). A similar increase in the odds ratio was observed between declining serum zinc and albuminuria but failed to reach statistical significance. Those with lower serum zinc/blood cadmium ratios were likewise at a greater risk of renal dysfunction (p<0.01). ConclusionsThis study results suggest that low serum zinc concentrations are associated with an increased risk of cadmium nephrotoxicity. Elevated cadmium exposure is global public health issue and the assessment of zinc nutritional status may be an important covariate in determining its effective renal toxicity.

Thermal neutron calibration channel at LNMRI/IRD

The Brazilian Metrology Laboratory of Ionizing Radiations (LNMRI) standard thermal neutron flux facility was designed to provide uniform neutron fluence for calibration of small neutron detectors and individual dosemeters. This fluence is obtained by neutron moderation from four (241)Am-Be sources, each with 596 GBq, in a facility built with blocks of graphite/paraffin compound and high-purity carbon graphite. This study was carried out in two steps. In the first step, simulations using the MCNPX code on different geometric arrangements of moderator materials and neutron sources were performed. The quality of the resulting neutron fluence in terms of spectrum, cadmium ratio and gamma-neutron ratio was evaluated. In the second step, the system was assembled based on the results obtained on the simulations, and new measurements are being made. These measurements will validate the system, and other intercomparisons will ensure traceability to the International System of Units.

Installation of a New Neutron Beam Facility at the U.S. Geological Survey TRIGA Reactor

The fleet of research and training reactors is aging, and no new research reactors are planned in the United States; thus, there is a need to expand the capabilities of existing reactors to meet users’ needs. To address these needs, the Colorado School of Mines added a neutron beamline facility to the U.S. Geological Survey TRIGA Reactor (GSTR), a 1-MW(thermal) Mark-I TRIGA reactor located at the Denver Federal Center in Lakewood, Colorado. The original GSTR design did not include any beam ports, and future research efforts will benefit from a neutron beam at the GSTR. Adding new beamline facilities to existing research reactors is both rare and challenging, and this paper describes the design and installation of a new neutron beamline facility at a Mark-I TRIGA reactor with no existing beamline facilities. The design and construction of a radiation beamstop for the new beamline is described in detail. A neutronics model of the neutron beam provides researchers with a useful tool for experiment design. The new neutron beam has a measured length-to-diameter ratio of 200 ± 10, a neutron flux of 2.2×106 ± 6.4×105 n/cm2-s, and an average cadmium ratio of 7.4 using copper, gold, manganese, and indium foils.