Determination of nickel in water, food, and biological samples by electrothermal atomic absorption spectrometry after preconcentration on modified carbon nanotubes.

PubMed

Taher, Mohammad Ali; Mazaheri, Lida; Ashkenani, Hamid; Mohadesi, Alireza; Afzali, Daryoush

2014-01-01

A new and sensitive SPE method using modified carbon nanotubes for extraction and preconcentration, and electrothermal atomic absorption spectrometric determination of nickel (Ni) in real samples at ng/L levels was investigated. First, multiwalled carbon nanotubes were oxidized with concentrated HNO3, then modified with 2-(5-bormo-2-pyridylazo)-5-diethylaminophenol reagent. The adsorption was achieved quantitatively on a modified carbon nanotubes column in a pH range of 6.5 to 8.5; the adsorbed Ni(II) ions were then desorbed by passing 5.0 mL of 1 M HNO3. The effects of analytical parameters, including pH of the solution, eluent type and volume, sample volume, flow rate of the eluent, and matrix ions, were investigated for optimization of the presented procedure. The enrichment factor was 180, and the LOD for Ni was 4.9 ng/L. The method was applied to the determination of Ni in water, food, and biological samples, and reproducible results were obtained.

Determination of gold, indium, tellurium and thallium in the same sample digest of geological materials by atomic-absorption spectroscopy and two-step solvent extraction

USGS Publications Warehouse

Hubert, A.E.; Chao, T.T.

1985-01-01

A rock, soil, or stream-sediment sample is decomposed with hydrofluoric acid, aqua regia, and hydrobromic acid-bromine solution. Gold, thallium, indium and tellurium are separated and concentrated from the sample digest by a two-step MIBK extraction at two concentrations of hydrobromic add. Gold and thallium are first extracted from 0.1M hydrobromic acid medium, then indium and tellurium are extracted from 3M hydrobromic acid in the presence of ascorbic acid to eliminate iron interference. The elements are then determined by flame atomic-absorption spectrophotometry. The two-step solvent extraction can also be used in conjunction with electrothermal atomic-absorption methods to lower the detection limits for all four metals in geological materials. ?? 1985.

Determination of arsenic in geological materials by electrothermal atomic-absorption spectrometry after hydride generation

USGS Publications Warehouse

Sanzolone, R.F.; Chao, T.T.; Welsch, E.P.

1979-01-01

Rock and soil samples are decomposed with HClO4-HNO3; after further treatment, arsine is generated and absorbed in a dilute silver nitrate solution. Aliquots of this solution are injected into a carbon rod atomizer. Down to 1 ppm As in samples can be determined and there are no significant interferences, even from chromium in soils. Good results were obtained for geochemical reference samples. ?? 1979.

Quantitative Ultrasound-Assisted Extraction for Trace-Metal Determination: An Experiment for Analytical Chemistry

ERIC Educational Resources Information Center

Lavilla, Isela; Costas, Marta; Pena-Pereira, Francisco; Gil, Sandra; Bendicho, Carlos

2011-01-01

Ultrasound-assisted extraction (UAE) is introduced to upper-level analytical chemistry students as a simple strategy focused on sample preparation for trace-metal determination in biological tissues. Nickel extraction in seafood samples and quantification by electrothermal atomic absorption spectrometry (ETAAS) are carried out by a team of four…

Electrothermal atomic absorption spectrometric determination of cobalt, copper, lead and nickel traces in aragonite following flotation and extraction separation.

PubMed

Zendelovska, D; Pavlovska, G; Cundeva, K; Stafilov, T

2001-03-30

A method of determination of Co, Cu, Pb and Ni in nanogram quantities from aragonite is presented. Flotation and extraction of Co, Cu, Pb and Ni is suggested as methods for elimination matrix interferences of calcium. The method of flotation is performed by iron(III) hexamethylenedithiocarbamate, Fe(HMDTC)(3), as a colloid precipitate collector. The liquid-liquid extraction of Co, Cu, Pb and Ni is carried out by sodium diethyldithiocarbamate, NaDDTC, as complexing reagent into methylisobutyl ketone, MIBK. The electrothermal atomic absorption spectrometry (ETAAS) is used for determination of analytes. The detection limits of ETAAS followed by flotation are: 7.8 ng.g(-1) for Co, 17.1 ng.g(-1) for Cu, 7.2 ng.g(-1) for Pb and 9.0 mug.g(-1) for Ni. The detection limits of ETAAS followed by extraction are found to be: 12.0 ng.g(-1) for Co, 51.0 ng.g(-1) for Cu, 24.0 ng.g(-1) for Pb and 21.0 ng.g(-1) for Ni.

Determination of Cu, Cd, Pb and Cr in yogurt by slurry sampling electrothermal atomic absorption spectrometry: A case study for Brazilian yogurt.

PubMed

de Andrade, Camila Kulek; de Brito, Patrícia Micaella Klack; Dos Anjos, Vanessa Egéa; Quináia, Sueli Pércio

2018-02-01

A slurry sampling electrothermal atomic absorption spectrometric method is proposed for the determination of trace elements such as Cu, Cr, Cd and Pb in yogurt. The main factors affecting the slurry preparation were optimized: nature and concentration of acid solution and sonication time. The analytical method was validated in-house by calibration, linearity, limits of detection and quantification, precision and accuracy test obtaining satisfactory results in all cases. The proposed method was applied for the determination of Cd, Cr, Cu and Pb in some Brazilian yogurt samples. For these samples, the concentrations ranged from 2.5±0.2 to 12.4±0.2ngg -1 ; 34±3 to 899±7ngg -1 ; <8.3 to 12±1ngg -1 ; and <35.4 to 210±16ngg -1 for Cd, Cu, Cr and Pb, respectively. The daily intake of Cd, Cu, Cr and Pb via consumption of these samples was estimated. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrothermal atomic absorption spectrometric determination of copper in nickel-base alloys with various chemical modifiers*1

NASA Astrophysics Data System (ADS)

Tsai, Suh-Jen Jane; Shiue, Chia-Chann; Chang, Shiow-Ing

1997-07-01

The analytical characteristics of copper in nickel-base alloys have been investigated with electrothermal atomic absorption spectrometry. Deuterium background correction was employed. The effects of various chemical modifiers on the analysis of copper were investigated. Organic modifiers which included 2-(5-bromo-2-pyridylazo)-5-(diethylamino-phenol) (Br-PADAP), ammonium citrate, 1-(2-pyridylazo)-naphthol, 4-(2-pyridylazo)resorcinol, ethylenediaminetetraacetic acid and Triton X-100 were studied. Inorganic modifiers palladium nitrate, magnesium nitrate, aluminum chloride, ammonium dihydrogen phosphate, hydrogen peroxide and potassium nitrate were also applied in this work. In addition, zirconium hydroxide and ammonium hydroxide precipitation methods have also been studied. Interference effects were effectively reduced with Br-PADAP modifier. Aqueous standards were used to construct the calibration curves. The detection limit was 1.9 pg. Standard reference materials of nickel-base alloys were used to evaluate the accuracy of the proposed method. The copper contents determined with the proposed method agreed closely with the certified values of the reference materials. The recoveries were within the range 90-100% with relative standard deviation of less than 10%. Good precision was obtained.

Column preconcentration and electrothermal atomic absorption spectrometric determination of rhodium in some food and standard samples.

PubMed

Taher, Mohammad Ali; Pourmohammad, Fatemeh; Fazelirad, Hamid

2015-12-01

In the present work, an electrothermal atomic absorption spectrometric method has been developed for the determination of ultra-trace amounts of rhodium after adsorption of its 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol/tetraphenylborate ion associated complex at the surface of alumina. Several factors affecting the extraction efficiency such as the pH, type of eluent, sample and eluent flow rates, sorption capacity of alumina and sample volume were investigated and optimized. The relative standard deviation for eight measurements of 0.1 ng/mL of rhodium was ±6.3%. In this method, the detection limit was 0.003 ng/mL in the original solution. The sorption capacity of alumina and the linear range for Rh(III) were evaluated as 0.8 mg/g and 0.015-0.45 ng/mL in the original solution, respectively. The proposed method was successfully applied for the extraction and determination of rhodium content in some food and standard samples with high recovery values. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Ligandless dispersive liquid--liquid microextraction of iron in biological and foodstuff samples and its determination by Electrothermal atomic absorption spectrometry.

PubMed

Madadizadeh, Mohadeseh; Taher, Mohammad Ali; Ashkenani, Hamid

2013-01-01

A new, simple, and efficient method comprising ligandless dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry is reported for the preconcentration and determination of ultratrace amounts of Fe(III). Carbon tetrachloride and acetone were used as the extraction and disperser solvents, respectively. Some effective parameters of the microextraction such as choice of extraction and disperser solvents, their volume, extraction time and temperature, salt and surfactant effect, and pH were optimized. Under the optimum conditions, the calibration curve was linear in the range of 0.02 to 0.46 microg/L of Fe(III), with LOD and LOQ of 5.2 and 17.4 ng/L, respectively. The RSD for seven replicated determinations of Fe(IIl) ion at 0.1 microg/L concentration level was 5.2%. Operational simplicity, rapidity, low cost, good repeatability, and low consumption of extraction solvent are the main advantages of the proposed method. The method was successfully applied to the determination of iron in biological, food, and certified reference samples.

Fast determination of phosphorus in honey, milk and infant formulas by electrothermal atomic absorption spectrometry using a slurry sampling procedure

NASA Astrophysics Data System (ADS)

López-García, I.; Viñas, P.; Romero-Romero, R.; Hernández-Córdoba, M.

2007-01-01

A procedure for the electrothermal atomic absorption spectrometric determination of phosphorus in honey, milk and infant formulas using slurried samples is described. Suspensions prepared in a medium containing 50% v/v concentrated hydrogen peroxide, 1% v/v concentrated nitric acid, 10% m/v glucose, 5% m/v sucrose and 100 mg l - 1 of potassium were introduced directly into the furnace. For the honey samples, multiple injection of the sample was necessary. The modifier selected was a mixture of 20 μg palladium and 5 μg magnesium nitrate, which was injected after the sample and before proceeding with the drying and calcination steps. Calibration was performed using aqueous standards prepared in the same suspension medium and the graph was linear between 5 and 80 mg l - 1 of phosphorus. The reliability of the procedure was checked by comparing the results obtained by the new developed method with those found when using a reference spectrophotometric method after a mineralization step, and by analyzing several certified reference materials.

Determination of sulphur in various vegetables by solid sampling high-resolution electrothermal molecular absorption spectrometry.

PubMed

Gunduz, Sema; Akman, Suleyman

2015-04-01

Sulphur was determined in various vegetables via molecular absorption of carbon monosulphide (CS) at 258.056 nm using a solid sampling high resolution continuum source electrothermal atomic absorption spectrometer (SS HR-CS ETAAS). Samples were dried, ground and directly introduced into the ruthenium coated graphite furnace as 0.05 to 0.50mg. All determinations were performed using palladium+citric acid modifier and applying a pyrolysis temperature of 1000 °C and a volatilisation temperature of 2400 °C. The results were in good agreement with certified sulphur concentrations of various vegetal CRM samples applying linear calibration technique prepared from thioacetamide. The limit of detection and characteristic mass of the method were 7.5 and 8.7 ng of S, respectively. The concentrations of S in various spinach, leek, lettuce, radish, Brussels sprouts, zucchini and chard samples were determined. It was showed that distribution of sulphur in CRM and grinded food samples were homogeneous even in micro-scale. Copyright © 2014 Elsevier Ltd. All rights reserved.

Current role of ICP-MS in clinical toxicology and forensic toxicology: a metallic profile.

PubMed

Goullé, Jean-Pierre; Saussereau, Elodie; Mahieu, Loïc; Guerbet, Michel

2014-08-01

As metal/metalloid exposure is inevitable owing to its omnipresence, it may exert toxicity in humans. Recent advances in metal/metalloid analysis have been made moving from flame atomic absorption spectrometry and electrothermal atomic absorption spectrometry to the multi-elemental inductively coupled plasma (ICP) techniques as ICP atomic emission spectrometry and ICP-MS. ICP-MS has now emerged as a major technique in inorganic analytical chemistry owing to its flexibility, high sensitivity and good reproducibility. This in depth review explores the ICP-MS metallic profile in human toxicology. It is now routinely used and of great importance, in clinical toxicology and forensic toxicology to explore biological matrices, specifically whole blood, plasma, urine, hair, nail, biopsy samples and tissues.

QA/QC Guidance for Sampling and Analysis of Sediments, Water, and Tissues for Dredged Material Evaluations: Chemical Evaluations

DTIC Science & Technology

1995-04-01

J. Biochem. Physiol. 37:911-917. Bloom, N.S., E.A. Crecelius, and S . Berman . 1983. Determination of mercury in seawater at sub-nanogram per liter...procedure for determination of trace metal in seawater by atomic absorption spectrometry with electrothermal atomization. Anal. Chern. Acta 98:47-55...Nakashima, S ., R.E. Sturgeon, S.N. Willie, and S.S. Berman . 1988. Acid digestion of marine sample for trace element analysis using microwave heating

In-situ suspended aggregate microextraction of gold nanoparticles from water samples and determination by electrothermal atomic absorption spectrometry.

PubMed

Choleva, Tatiana G; Kappi, Foteini A; Tsogas, George Z; Vlessidis, Athanasios G; Giokas, Dimosthenis L

2016-05-01

This work describes a new method for the extraction and determination of gold nanoparticles in environmental samples by means of in-situ suspended aggregate microextraction and electrothermal atomic absorption spectrometry. The method relies on the in-situ formation of a supramolecular aggregate phase through ion-association between a cationic surfactant and a benzene sulfonic acid derivative. Gold nanoparticles are physically entrapped into the aggregate phase which is separated from the bulk aqueous solution by vacuum filtration on the surface of a cellulose filter in the form of a thin film. The film is removed from the filter surface and is dissociated into an acidified methanolic solution which is used for analysis. Under the optimized experimental conditions, gold nanoparticles can be efficiently extracted from water samples with recovery rates between 81.0-93.3%, precision 5.4-12.0% and detection limits as low as 75femtomolL(-1) using only 20mL of sample volume. The satisfactory analytical features of the method along with the simplicity indicate the efficiency of this new approach to adequately collect and extract gold nanoparticle species from water samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Synthesis and application of a nanoporous ion-imprinted polymer for the separation and preconcentration of trace amounts of vanadium from food samples before determination by electrothermal atomic absorption spectrometry.

PubMed

Dadfarnia, Shayessteh; Haji Shabani, Ali Mohammad; Dehghanpoor Frashah, Shahab

2016-04-01

A vanadium ion-imprinted polymer was synthesized in the presence of V(V) and N-benzoyl-N-phenyl hydroxyl amine using 4-vinyl pyridine as the monomer, ethylene glycol dimethacrylate as the cross linker and 2,2'-azobis(isobutyronitrile) as the initiator. The imprinted V(V) ions were completely removed by leaching the polymer with 5 mol/L nitric acid, and the polymer structure was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The ion-imprinted polymer was used as the sorbent in the development of the solid-phase extraction method for V(V) prior to its determination by electrothermal atomic absorption spectrometry. The maximum sorption capacity for V(V) ions was 26.7 mg/g at pH 4.0. Under the optimum conditions, for a sample volume of 150.0 mL, an enrichment factor of 289.0 and a detection limit of 6.4 ng/L were obtained. The developed method was successfully applied to the determination of vanadium in parsley, zucchini, black tea, rice, and water samples. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Toxic metals distribution in different components of Pakistani and imported cigarettes by electrothermal atomic absorption spectrometer.

PubMed

Kazi, T G; Jalbani, N; Arain, M B; Jamali, M K; Afridi, H I; Sarfraz, R A; Shah, A Q

2009-04-15

It was extensively investigated that a significant flux of toxic metals, along with other toxins, reaches the lungs through smoking. In present study toxic metals (TMs) (Al, Cd, Ni and Pb) were determined in different components of Pakistani local branded and imported cigarettes, including filler tobacco (FT), filter (before and after normal smoking by a single volunteer) and ash by electrothermal atomic absorption spectrometer (ETAAS). Microwave-assisted digestion method was employed. The validity and accuracy of methodology were checked by using certified sample of Virginia tobacco leaves (ICHTJ-cta-VTL-2). The percentages (%) of TMs in different components of cigarette were calculated with respect to their total contents in FT of all branded cigarettes before smoking, while smoke concentration has been calculated by subtracting the filter and ash contents from the filler tobacco content of each branded cigarette. The highest percentage (%) of Al was observed in ash of all cigarettes, with range 97.3-99.0%, while in the case of Cd, a reverse behaviour was observed, as a range of 15.0-31.3% of total contents were left in the ash of all branded cigarettes understudy.

Preconcentration of lead using solidification of floating organic drop and its determination by electrothermal atomic absorption spectrometry

PubMed Central

Chamsaz, Mahmoud; Akhoundzadeh, Jeiran; Arbab-zavar, Mohammad Hossein

2012-01-01

A simple microextraction method based on solidification of a floating organic drop (SFOD) was developed for preconcentration of lead prior to its determination by electrothermal atomic absorption spectrometry (ETAAS). Ammonium pyrolidinedithiocarbamate (APDC) was used as complexing agent, and the formed complex was extracted into a 20 μL of 1-undecanol. The extracted complex was diluted with ethanol and injected into a graphite furnace. An orthogonal array design (OAD) with OA16 (45) matrix was employed to study the effects of different parameters such as pH, APDC concentration, stirring rate, sample solution temperature and the exposure time on the extraction efficiency. Under the optimized experimental conditions the limit of detection (based on 3 s) and the enhancement factor were 0.058 μg L−1 and 113, respectively. The relative standard deviation (RSD) for 8 replicate determinations of 1 μg L−1 of Pb was 8.8%. The developed method was validated by the analysis of certified reference materials and was successfully applied to the determination of lead in water and infant formula base powder samples. PMID:25685441

Separation/preconcentration and determination of vanadium with dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) and electrothermal atomic absorption spectrometry.

PubMed

Asadollahi, Tahereh; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji

2010-06-30

A novel dispersive liquid-liquid microextraction based on solidification of floating organic drop (DLLME-SFO) for separation/preconcentration of ultra trace amount of vanadium and its determination with the electrothermal atomic absorption spectrometry (ETAAS) was developed. The DLLME-SFO behavior of vanadium (V) using N-benzoyl-N-phenylhydroxylamine (BPHA) as complexing agent was systematically investigated. The factors influencing the complex formation and extraction by DLLME-SFO method were optimized. Under the optimized conditions: 100 microL, 200 microL and 25 mL of extraction solvent (1-undecanol), disperser solvent (acetone) and sample volume, respectively, an enrichment factor of 184, a detection limit (based on 3S(b)/m) of 7 ng L(-1) and a relative standard deviation of 4.6% (at 500 ng L(-1)) were obtained. The calibration graph using the preconcentration system for vanadium was linear from 20 to 1000 ng L(-1) with a correlation coefficient of 0.9996. The method was successfully applied for the determination of vanadium in water and parsley. Copyright 2010 Elsevier B.V. All rights reserved.

Ionic liquid-assisted multiwalled carbon nanotube-dispersive micro-solid phase extraction for sensitive determination of inorganic As species in garlic samples by electrothermal atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Grijalba, Alexander Castro; Escudero, Leticia B.; Wuilloud, Rodolfo G.

2015-08-01

A highly sensitive dispersive micro-solid phase extraction (D-μ-SPE) method combining an ionic liquid (IL) and multi-walled carbon nanotubes (MWCNTs) for inorganic As species (As(III) and As(V)) species separation and determination in garlic samples by electrothermal atomic absorption spectrometry (ETAAS) was developed. Trihexyl(tetradecil)phosphonium chloride IL was used to form an ion pair with the arsenomolybdate complex obtained by reaction of As(V) with molybdate ion. Afterwards, 1.0 mg of MWCNTs was dispersed for As(V) extraction and the supernatant was separated by centrifugation. MWCNTs were re-dispersed with tetradecyltrimethylammonium bromide surfactant and ultrasound followed by direct injection into the graphite furnace of ETAAS for As determination. Pyrolysis and atomization conditions were carefully studied for complete decomposition of MWCNTs and IL matrices. Under optimum conditions, an extraction efficiency of 100% and a preconcentration factor of 70 were obtained with 5 mL of garlic extract. The detection limit was 7.1 ng L- 1 and the relative standard deviations (RSDs) for six replicate measurements at 5 μg L- 1 of As were 5.4% and 4.8% for As(III) and As(V), respectively. The proposed D-μ-SPE method allowed the efficient separation and determination of inorganic As species in a complex matrix such as garlic extract.

Preconcentration and determination of boron in milk, infant formula, and honey samples by solid phase extraction-electrothermal atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

López-García, I.; Viñas, P.; Romero-Romero, R.; Hernández-Córdoba, M.

2009-02-01

This work presents alternative procedures for the electrothermal atomic absorption spectrometric determination of boron in milk, infant formulas, and honey samples. Honey samples (10% m/v) were diluted in a medium containing 1% v/v HNO 3 and 50% v/v H 2O 2 and introduced in the atomizer. A mixture of 20 µg Pd and 0.5 µg Mg was used for chemical modification. Calibration was carried out using aqueous solutions prepared in the same medium, in the presence of 10% m/v sucrose. The detection limit was 2 µg g - 1 , equivalent to three times the standard error of the estimate ( sy/ x) of the regression line. For both infant formulas and milk samples, due to their very low boron content, we used a procedure based on preconcentration by solid phase extraction (Amberlite IRA 743), followed by elution with 2 mol L - 1 hydrochloric acid. Detection limits were 0.03 µg g - 1 for 4% m/v honey, 0.04 µg g - 1 for 5% m/v infant formula and 0.08 µg mL - 1 for 15% v/v cow milk. We confirmed the accuracy of the procedure by comparing the obtained results with those found via a comparable independent procedure, as well by the analysis of four certified reference materials.

Gold in natural water: A method of determination by solvent extraction and electrothermal atomization

USGS Publications Warehouse

McHugh, J.B.

1984-01-01

A method has been developed using electrothermal atomization to effectively determine the amount of gold in natural water within the nanogram range. The method has four basic steps: (1) evaporating a 1-L sample; (2) putting it in hydrobromic acid-bromine solution; (3) extracting the sample with methyl-isobutyl-ketone; and (4) determining the amount of gold using an atomic absorption spectrophotometer. The limit of detection is 0.001 ??g gold per liter. Results from three studies indicate, respectively, that the method is precise, effective, and free of interference. Specifically, a precision study indicates that the method has a relative standard deviation of 16-18%; a recovery study indicates that the method recovers gold at an average of 93%; and an interference study indicates that the interference effects are eliminated with solvent extraction and background correction techniques. Application of the method to water samples collected from 41 sites throughout the Western United States and Alaska shows a gold concentration range of < 0.001 to 0.036 ??g gold per liter, with an average of 0.005 ??g/L. ?? 1984.

Spectral and non-spectral interferences in the determination of thallium in environmental materials using electrothermal atomization and vaporization techniques—a case study

NASA Astrophysics Data System (ADS)

Vale, Maria Goreti R.; Welz, Bernhard

2002-12-01

The literature on the determination of Tl in environmental samples using electrothermal atomization (ETA) and vaporization (ETV) techniques has been reviewed with special attention devoted to potential interferences and their control. Chloride interference, which is due to the formation of the volatile monochloride in the condensed phase, is the most frequently observed problem. Due to its high dissociation energy (88 kcal/mol), TlCl is difficult to dissociate in the gas phase and is easily lost. The best means of controlling this interference in ETA is atomization under isothermal conditions according to the stabilized temperature platform furnace concept, and the use of reduced palladium as a modifier. An alternative approach appears to be the 'fast furnace' concept, wherein both the use of a modifier and the pyrolysis stage are omitted. This concept requires an efficient background correction system, and high-resolution continuum-source atomic absorption spectrometry (HR-CS AAS) appears to offer the best results. This chloride interference can also cause significant problems when ETV techniques are used. Among the spectral interferences found in the determination of thallium are those due to Pd, the most efficient modifier, and Fe, which is frequently found at high concentrations in environmental samples. Both interferences are due to nearby atomic lines, and are observed only when deuterium background correction and relatively high atomization temperatures are used. A more serious spectral interference is that due to the molecular absorption spectrum of SO 2, which has a maximum around the Tl line and exhibits a pronounced rotational fine structure. HR-CS AAS again showed the best performance in coping with this interference.

Determining gold in water by anion-exchange batch extraction

USGS Publications Warehouse

McHugh, J.B.

1986-01-01

This paper describes a batch procedure for determining gold in natural waters. It is completely adaptable to field operations. The water samples are filtered and acidified before they are equilibrated with an anion-exchange resin by shaking. The gold is then eluted with acetone-nitric acid solution, and the eluate evaporated to dryness. The residue is taken up in hydrobromic acid-bromine solution and the gold is extracted with methyl isobutyl ketone. The extract is electrothermally atomized in an atomic-absorption spectrophotometer. The limit of determination is 1 ng 1. ?? 1986.

Species selective preconcentration and quantification of gold nanoparticles using cloud point extraction and electrothermal atomic absorption spectrometry.

PubMed

Hartmann, Georg; Schuster, Michael

2013-01-25

The determination of metallic nanoparticles in environmental samples requires sample pretreatment that ideally combines pre-concentration and species selectivity. With cloud point extraction (CPE) using the surfactant Triton X-114 we present a simple and cost effective separation technique that meets both criteria. Effective separation of ionic gold species and Au nanoparticles (Au-NPs) is achieved by using sodium thiosulphate as a complexing agent. The extraction efficiency for Au-NP ranged from 1.01 ± 0.06 (particle size 2 nm) to 0.52 ± 0.16 (particle size 150 nm). An enrichment factor of 80 and a low limit of detection of 5 ng L(-1) is achieved using electrothermal atomic absorption spectrometry (ET-AAS) for quantification. TEM measurements showed that the particle size is not affected by the CPE process. Natural organic matter (NOM) is tolerated up to a concentration of 10 mg L(-1). The precision of the method expressed as the standard deviation of 12 replicates at an Au-NP concentration of 100 ng L(-1) is 9.5%. A relation between particle concentration and the extraction efficiency was not observed. Spiking experiments showed a recovery higher than 91% for environmental water samples. Copyright © 2012 Elsevier B.V. All rights reserved.

Determination of trace nickel in hydrogenated cottonseed oil by electrothermal atomic absorption spectrometry after microwave-assisted digestion.

PubMed

Zhang, Gai

2012-01-01

Microwave digestion of hydrogenated cottonseed oil prior to trace nickel determination by electrothermal atomic absorption spectrometry (ETAAS) is proposed here for the first time. Currently, the methods outlined in U.S. Pharmacopeia 28 (USP28) or British Pharmacopeia (BP2003) are recommended as the official methods for analyzing nickel in hydrogenated cottonseed oil. With these methods the samples may be pre-treated by a silica or a platinum crucible. However, the samples were easily tarnished during sample pretreatment when using a silica crucible. In contrast, when using a platinum crucible, hydrogenated cottonseed oil acting as a reducing material may react with the platinum and destroy the crucible. The proposed microwave-assisted digestion avoided tarnishing of sample in the process of sample pretreatment and also reduced the cycle of analysis. The programs of microwave digestion and the parameters of ETAAS were optimized. The accuracy of the proposed method was investigated by analyzing real samples. The results were compared with the ones by pressurized-PTFE-bomb acid digestion and ones obtained by the U.S. Pharmacopeia 28 (USP28) method. The new method involves a relatively rapid matrix destruction technique compared with other present methods for the quantification of metals in oil. © 2011 Institute of Food Technologists®

Electrothermal atomic absorption spectrometric determination of arsenic in essential lavender and rose oils.

PubMed

Karadjova, Irina B; Lampugnani, Leonardo; Tsalev, Dimiter L

2005-02-28

Analytical procedures for electrothermal atomic absorption spectrometric (ETAAS) determination of arsenic in essential oils from lavender (Lavendula angustifolia) and rose (Rosa damascena) are described. For direct ETAAS analysis, oil samples are diluted with ethanol or i-propanol for lavender and rose oil, respectively. Leveling off responses of four different arsenic species (arsenite, arsenate, monomethylarsonate and dimethylarsinate) is achieved by using a composite chemical modifier: l-cysteine (0.05gl(-1)) in combination with palladium (2.5mug) and citric acid (100mug). Transverse-heated graphite atomizer (THGA) with longitudinal Zeeman-effect background correction and 'end-capped' graphite tubes with integrated pyrolytic graphite platforms, pre-treated with Zr-Ir for permanent modification are employed as most appropriate atomizer. Calibration with solvent-matched standard solutions of As(III) is used for four- and five-fold diluted samples of lavender and rose oil, respectively. Lower dilution factors required standard addition calibration by using aqueous (for lavender oil) or i-propanol (for rose oil) solutions of As(III). The limits of detection (LOD) for the whole analytical procedure are 4.4 and 4.7ngg(-1) As in levender and rose oil, respectively. The relative standard deviation (R.S.D.) for As at 6-30ngg(-1) levels is between 8 and 17% for both oils. As an alternative, procedure based on low temperature plasma ashing in oxygen with ETAAS, providing LODs of 2.5 and 2.7ngg(-1) As in levender and rose oil, respectively, and R.S.D. within 8-12% for both oils has been elaborated. Results obtained by both procedures are in good agreement.

Ultratrace determination of arsenic in water samples by electrothermal atomic absorption spectrometry after pre-concentration with Mg-Al-Fe ternary layered double hydroxide nano-sorbent.

PubMed

Abdolmohammad-Zadeh, Hossein; Jouyban, Abolghasem; Amini, Roghayeh

2013-11-15

A selective solid phase extraction method, based on nano-structured Mg-Al-Fe(NO3(-)) ternary layered double hydroxide as a sorbent, is developed for the pre-concentration of ultra-trace levels of arsenic (As) prior to determination by electrothermal atomic absorption spectrometry. It is found that both As(III) and As(V) could be quantitatively retained on the sorbent within a wide pH range of 4-12. Accordingly, the presented method is applied to determination of total inorganic As in aqueous solutions. Maximum analytical signal of As is achieved when the pyrolysis and atomization temperatures are close to 900 °C and 2300 °C, respectively. Several variables affecting the extraction efficiency including pH, sample flow rate, amount of nano-sorbent, elution conditions and sample volume are optimized. Under the optimized conditions, the limit of detection (3Sb/m) and the relative standard deviation are 4.6 pg mL(-1) and 3.9%, respectively. The calibration graph is linear in the range of 15.0-650 pg mL(-1) with a correlation coefficient of 0.9979, sorption capacity and pre-concentration factor are 8.68 mg g(-1) and 300, respectively. The developed method is validated by the analysis of a standard reference material (SRM 1643e) and is successfully applied to the determination of ultra-trace amounts of As in different water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

Selenium analysis by an integrated microwave digestion-needle trap device with hydride sorption on carbon nanotubes and electrothermal atomic absorption spectrometry determination

NASA Astrophysics Data System (ADS)

Maratta Martínez, Ariel; Vázquez, Sandra; Lara, Rodolfo; Martínez, Luis Dante; Pacheco, Pablo

2018-02-01

An integrated microwave assisted digestion (MW-AD) - needle trap device (NTD) for selenium determination in grape pomace samples is presented. The NTD was filled with oxidized multiwall carbon nanotubes (oxMWCNTS) where Se hydrides were preconcentrated. Determination was carried out by flow injection-electrothermal atomic absorption spectrometry (FI-ETAAS). The variables affecting the system were established by a multivariate design (Plackett Burman), indicating that the following variables significantly affect the system: sample amount, HNO3 digestion solution concentration, NaBH4 volume and elution volume. A Box-Behnken design was implemented to determine the optimized values of these variables. The system improved Se atomization in the graphite furnace, since only trapped hydrides reached the graphite furnace, and the pyrolysis stage was eliminated according to the aqueous matrix of the eluate. Under optimized conditions the system reached a limit of quantification of 0.11 μg kg- 1, a detection limit of 0.032 μg kg- 1, a relative standard deviation of 4% and a preconcentration factor (PF) of 100, reaching a throughput sample of 5 samples per hour. Sample analysis show Se concentrations between 0.34 ± 0.03 μg kg- 1 to 0.48 ± 0.03 μg kg- 1 in grape pomace. This system provides minimal reagents and sample consumption, eliminates discontinuous stages between samples processing reaching a simpler and faster Se analysis.

Multiwalled carbon nanotubes as a sorbent material for the solid phase extraction of lead from urine and subsequent determination by electrothermal atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Peña Crecente, Rosa M.; Lovera, Carlha Gutiérrez; García, Julia Barciela; Méndez, Jennifer Álvarez; Martín, Sagrario García; Latorre, Carlos Herrero

2014-11-01

The determination of lead in urine is a way of monitoring the chemical exposure to this metal. In the present paper, a new method for the Pb determination by electrothermal atomic absorption spectrometry (ETAAS) in urine at low levels has been developed. Lead was separated from the undesirable urine matrix by means of a solid phase extraction (SPE) procedure. Oxidized multiwalled carbon nanotubes have been used as a sorbent material. Lead from urine was retained at pH 4.0 and was quantitatively eluted using a 0.7 M nitric acid solution and was subsequently measured by ETAAS. The effects of parameters that influence the adsorption-elution process (such as pH, eluent volume and concentration, sampling and elution flow rates) and the atomic spectrometry conditions have been studied by means of different factorial design strategies. Under the optimized conditions, the detection and quantification limits obtained were 0.08 and 0.26 μg Pb L- 1, respectively. The results demonstrate the absence of a urine matrix effect and this is the consequence of the SPE process carried out. Therefore, the developed method is useful for the analysis of Pb at low levels in real samples without the influence of other urine components. The proposed method was applied to the determination of lead in urine samples of unexposed healthy people and satisfactory results were obtained (in the range 3.64-22.9 μg Pb L- 1).

Blood-collection device for trace and ultra-trace metal specimens evaluated.

PubMed

Moyer, T P; Mussmann, G V; Nixon, D E

1991-05-01

We evaluated the evacuated phlebotomy tube designed specifically for trace metal analysis by Sherwood Medical Co. Pools of human serum containing known concentrations of aluminum, arsenic, calcium, cadmium, copper, chromium, iron, lead, magnesium, manganese, mercury, selenium, and zinc were exposed to the tube and rubber stopper for defined periods ranging from 5 min to 24 h. Analysis for each element was performed in a randomized fashion under rigidly controlled conditions by use of standard electrothermal atomization atomic absorption spectroscopy, inductively coupled plasma atomic emission spectroscopy, and cold vapor atomic absorption spectrometry. In addition, for comparative purposes, we collected blood samples from normal volunteers by use of ultra-clean polystyrene phlebotomy syringes as well as standard evacuated phlebotomy tubes. We conclude that, except for lead, there was no significant contribution of any trace element studied from the evaluated tube and stopper to the serum. Because whole blood is the usual specimen for lead testing, the observation of a trace amount of lead in this tube designed for serum collection is trivial.

Analytical characteristics of a continuum-source tungsten coil atomic absorption spectrometer.

PubMed

Rust, Jennifer A; Nóbrega, Joaquim A; Calloway, Clifton P; Jones, Bradley T

2005-08-01

A continuum-source tungsten coil electrothermal atomic absorption spectrometer has been assembled, evaluated, and employed in four different applications. The instrument consists of a xenon arc lamp light source, a tungsten coil atomizer, a Czerny-Turner high resolution monochromator, and a linear photodiode array detector. This instrument provides simultaneous multi-element analyses across a 4 nm spectral window with a resolution of 0.024 nm. Such a device might be useful in many different types of analyses. To demonstrate this broad appeal, four very different applications have been evaluated. First of all, the temperature of the gas phase was measured during the atomization cycle of the tungsten coil, using tin as a thermometric element. Secondly, a summation approach for two absorption lines for aluminum falling within the same spectral window (305.5-309.5 nm) was evaluated. This approach improves the sensitivity without requiring any additional preconcentration steps. The third application describes a background subtraction technique, as it is applied to the analysis of an oil emulsion sample. Finally, interference effects caused by Na on the atomization of Pb were studied. The simultaneous measurements of Pb and Na suggests that negative interference arises at least partially from competition between Pb and Na atoms for H2 in the gas phase.

Flotation separation and electrothermal atomic absorption spectrometric determination of thallium in wastewater samples.

PubMed

Hosseini, Mohammad Saeid; Chamsaz, Mahmoud; Raissi, Heidar; Naseri, Yousef

2006-01-01

The proposed method is a simple process for the determination of trace amount of thallium(I) in the environmental wastewater samples by electrothermal atomic absorption spectrometry. The wastewater samples were obtained from the environment of a cement plant and subjected to a simple treatment, such as adjusting pH and masking the interfering ions, to prepare for the flotation process in which the thallium(I) content was floated as an ion-association complex using iodide and Rhodamine B at the interface of aqueous/cyclohexane layers. The floated layer was then separated and dissolved in 2 ml of a solution, which was 1% to H2SO4 and 50% to methanol, respectively. Aliquots of 10-microl of this solution were subjected to the graphite furnace to determine the thallium(I) content. The flotation process can be carried in a weak acidic medium in which the interfering effects owing to certain metal ions were eliminated by masking them as neutral citrate chelates. The dynamic range for the determination was found to be 1.0 x 10(-8) - 1.0 x 10(-7) mol l(-1). The RSD was 3.2% and the DL was 2.5 x 10(-9) mol l(-1) (calculated as 3SD of the blank). The reliability of the method is demonstrated by the analysis of a synthetic wastewater in which the recovery was found to be 94%.

Differential determination of chromium(VI) and total chromium in natural waters using flow injection on-line separation and preconcentration electrothermal atomic absorption spectrometry.

PubMed

Sperling, M; Yin, X; Welz, B

1992-03-01

A rapid, sensitive and selective method for the differential determination of CrIII and CrVI in natural waters is described. Chromium(vi) can be determined directly by flow injection on-line sorbent extraction preconcentration coupled with electrothermal atomic absorption spectrometry using sodium diethyldithiocarbamate as the complexing agent and C18 bonded silica reversed-phase sorbent as the column material. Total Cr can be determined after oxidation of CrIII to CrVI by potassium peroxydisulfate. Chromium(III) can be calculated by difference. The optimum conditions for sorbent extraction of CrVI and oxidation of CrIII to CrVI are evaluated. A 12-fold enhancement in sensitivity compared with direct introduction of 40 microliters samples was achieved after preconcentration for 60 s, giving detection limits of 16 ng l-1 for CrVI and 18 ng l-1 for total Cr (based on 3 sigma). Results obtained for sea-water and river water reference materials were all within the certified range for total Cr with a precision of better than 10% relative standard deviation in the range 100-200 ng l-1. The selectivity of the determination of CrVI was evaluated by analysing spiked reference materials in the presence of CrIII, resulting in quantitative recovery of CrVI.

Determination of sub-microgram amounts of selenium in geological materials by atomic-absorption spectrophotometry with electrothermal atomisation after solvent extraction

USGS Publications Warehouse

Sanzolone, R.F.; Chao, T.T.

1981-01-01

An atomic-absorption spectrophotometric method with electrothermal atomisation has been developed for the determination of selenium in geological materials. The sample is decomposed with a mixture of nitric, perchloric and hydrofluoric acids and heated with hydrochloric acid to reduce selenium to selenium (IV). Selenium is then extracted into toluene from a hydrochloric acid - hydrobromic acid medium containing iron. A few microlitres of the toluene extract are injected into a carbon rod atomiser, using a nickel solution as a matrix modifier. The limits of determination are 0.2-200 p.p.m. of selenium in a geological sample. For concentrations between 0.05 and 0.2 p.p.m., back-extraction of the selenium into dilute hydrochloric acid is employed before atomisation. Selenium values for reference samples obtained by replicate analysis are in general agreement with those reported by other workers, with relative standard deviations ranging from 4.1 to 8.8%. Recoveries of selenium spiked at two levels were 98-108%. Major and trace elements commonly encountered in geological materials do not interfere. Arsenic has a suppressing effect on the selenium signals, but only when its concentration is greater than 1000 p.p.m. Nitric acid interferes seriously with the extraction of selenium and must be removed by evaporation in the sample-digestion step.

Three-dimensional time-dependent computer modeling of the electrothermal atomizers for analytical spectrometry

NASA Astrophysics Data System (ADS)

Tsivilskiy, I. V.; Nagulin, K. Yu.; Gilmutdinov, A. Kh.

2016-02-01

A full three-dimensional nonstationary numerical model of graphite electrothermal atomizers of various types is developed. The model is based on solution of a heat equation within solid walls of the atomizer with a radiative heat transfer and numerical solution of a full set of Navier-Stokes equations with an energy equation for a gas. Governing equations for the behavior of a discrete phase, i.e., atomic particles suspended in a gas (including gas-phase processes of evaporation and condensation), are derived from the formal equations molecular kinetics by numerical solution of the Hertz-Langmuir equation. The following atomizers test the model: a Varian standard heated electrothermal vaporizer (ETV), a Perkin Elmer standard THGA transversely heated graphite tube with integrated platform (THGA), and the original double-stage tube-helix atomizer (DSTHA). The experimental verification of computer calculations is carried out by a method of shadow spectral visualization of the spatial distributions of atomic and molecular vapors in an analytical space of an atomizer.

Direct determination of Pb in raw milk by graphite furnace atomic absorption spectrometry (GF AAS) with electrothermal atomization sampling from slurries.

PubMed

de Oliveira, Tatiane Milão; Augusto Peres, Jayme; Lurdes Felsner, Maria; Cristiane Justi, Karin

2017-08-15

Milk is an important food in the human diet due to its physico-chemical composition; therefore, it is necessary to monitor contamination by toxic metals such as Pb. Milk sample slurries were prepared using Triton X-100 and nitric acid for direct analysis of Pb using graphite furnace atomic absorption spectrometry - GF AAS. After dilution of the slurries, 10.00µl were directly introduced into the pyrolytic graphite tube without use of a chemical modifier, which acts as an advantage considering this type of matrix. The limits of detection and quantification were 0.64 and 2.14µgl -1 , respectively. The figures of merit studied showed that the proposed methodology without pretreatment of the raw milk sample and using external standard calibration is suitable. The methodology was applied in milk samples from the Guarapuava region, in Paraná State (Brazil) and Pb concentrations ranged from 2.12 to 37.36µgl -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Lead concentrations and isotope ratios in street dust determined by electrothermal atomic absorption spectrometry and inductively coupled plasma mass spectrometry.

PubMed

Nageotte, S M; Day, J P

1998-01-01

A major source of environmental lead, particularly in urban areas, has been from the combustion of leaded petrol. Street dust has previously been used to assess urban lead contamination, and the dust itself can also be a potential source of lead ingestion, particularly to children. The progressive reduction of lead in petrol, in recent years, would be expected to have been reflected in a reduction of lead in urban dust. We have tested this hypothesis by repeating an earlier survey of Manchester street dust and carrying out a comparable survey in Paris. Samples were collected from streets and parks, lead was extracted by digestion with concentrated nitric acid and determined by electrothermal atomic absorption spectrometry. Lead isotope ratios were measured by inductively coupled plasma mass spectrometry. Results for Manchester show that lead concentrations have fallen by about 40% (street dust averages, 941 micrograms g-1 (ppm) in 1975 down to 569 ppm in 1997). In Paris, the lead levels in street dust are much higher and significant differences were observed between types of street (not seen in Manchester). Additionally, lead levels in parks were much lower than in Manchester. Samples collected under the Eiffel Tower had very high concentrations and lead isotope ratios showed that this was unlikely to be fallout from motor vehicles but could be due to the paint used on the tower. Isotope ratios measurements also revealed that lead additives used in France and the UK come from different sources.

Reduction of interferences in graphite furnace atomic absorption spectrometry by multiple linear regression modelling

NASA Astrophysics Data System (ADS)

Grotti, Marco; Abelmoschi, Maria Luisa; Soggia, Francesco; Tiberiade, Christian; Frache, Roberto

2000-12-01

The multivariate effects of Na, K, Mg and Ca as nitrates on the electrothermal atomisation of manganese, cadmium and iron were studied by multiple linear regression modelling. Since the models proved to efficiently predict the effects of the considered matrix elements in a wide range of concentrations, they were applied to correct the interferences occurring in the determination of trace elements in seawater after pre-concentration of the analytes. In order to obtain a statistically significant number of samples, a large volume of the certified seawater reference materials CASS-3 and NASS-3 was treated with Chelex-100 resin; then, the chelating resin was separated from the solution, divided into several sub-samples, each of them was eluted with nitric acid and analysed by electrothermal atomic absorption spectrometry (for trace element determinations) and inductively coupled plasma optical emission spectrometry (for matrix element determinations). To minimise any other systematic error besides that due to matrix effects, accuracy of the pre-concentration step and contamination levels of the procedure were checked by inductively coupled plasma mass spectrometric measurements. Analytical results obtained by applying the multiple linear regression models were compared with those obtained with other calibration methods, such as external calibration using acid-based standards, external calibration using matrix-matched standards and the analyte addition technique. Empirical models proved to efficiently reduce interferences occurring in the analysis of real samples, allowing an improvement of accuracy better than for other calibration methods.

A highly selective and sensitive ultrasonic assisted dispersive liquid phase microextraction based on deep eutectic solvent for determination of cadmium in food and water samples prior to electrothermal atomic absorption spectrometry.

PubMed

Zounr, Rizwan Ali; Tuzen, Mustafa; Deligonul, Nihal; Khuhawar, Muhammad Yar

2018-07-01

A simple, fast, green, sensitive and selective ultrasonic assisted deep eutectic solvent liquid-phase microextraction technique was used for preconcentration and extraction of cadmium (Cd) in water and food samples by electrothermal atomic absorption spectrometry (ETAAS). In this technique, a synthesized reagent (Z)-N-(3,5-diphenyl-1H-pyrrol-2-yl)-3,5-diphenyl-2H-pyrrol-2-imine (Azo) was used as a complexing agent for Cd. The main factors effecting the pre-concentration and extraction of Cd such as effect of pH, type and composition of deep eutectic solvent (DES), volume of DES, volume of complexing agent, volume of tetrahydrofuran (THF) and ultrasonication time have been examined in detail. At optimum conditions the value of pH and molar ratio of DES were found to be 6.0 and 1:4 (ChCl:Ph), respectively. The detection limit (LOD), limit of quantification (LOQ), relative standard deviation (RSD) and preconcentration factor (PF) were observed as 0.023 ng L -1 , 0.161 ng L -1 , 3.1% and 100, correspondingly. Validation of the developed technique was observed by extraction of Cd in certified reference materials (CRMs) and observed results were successfully compared with certified values. The developed procedure was practiced to various food, beverage and water samples. Copyright © 2018 Elsevier Ltd. All rights reserved.

Simultaneous speciation and preconcentration of ultra traces of inorganic tellurium and selenium in environmental samples by hollow fiber liquid phase microextraction prior to electrothermal atomic absorption spectroscopy determination.

PubMed

Ghasemi, Ensieh; Najafi, Nahid Mashkouri; Raofie, Farhad; Ghassempour, Alireza

2010-09-15

A simple and effective speciation and preconcentration method based on hollow fiber liquid phase microextraction (HF-LPME) was developed for simultaneous separation of trace inorganic tellurium and selenium in environmental samples prior to electrothermal atomic absorption spectroscopy (ETAAS) determination. The method involves the selective extraction of the Te (IV) and Se (IV) species by HF-LPME with the use of ammonium pyrrolidinecarbodithioate (APDC) as the chelating agent. The complex compounds were extracted into 10 microL of toluene and the solutions were injected into a graphite furnace for the determination of Te (IV) and Se (IV). To determine the total tellurium and selenium in the samples, first Te (VI) and Se (VI) were reduced to Te (IV) and Se (IV), and then the microextraction method was performed. The experimental parameters of HF-LPME were optimized using a central composite design after a 2(n-1) fractional factorial experimental design. Under optimum conditions, enrichment factors of up to 520 and 480 were achieved for Te (IV) and Se (IV), respectively. The detection limits were 4 ng L(-1) with 3.5% RSD (n=5, c=2.0 microg L(-1)) for Te (IV) and 5 ng L(-1) with 3.1% RSD for Se (IV). The applicability of the developed technique was evaluated by application to spiked, environmental water and soil samples. Copyright 2010 Elsevier B.V. All rights reserved.

Separation, identification and quantification of carotenoids and chlorophylls in dietary supplements containing Chlorella vulgaris and Spirulina platensis using High Performance Thin Layer Chromatography.

PubMed

Hynstova, Veronika; Sterbova, Dagmar; Klejdus, Borivoj; Hedbavny, Josef; Huska, Dalibor; Adam, Vojtech

2018-01-30

In this study, 14 commercial products (dietary supplements) containing alga Chlorella vulgaris and cyanobacteria Spirulina platensis, originated from China and Japan, were analysed. UV-vis spectrophotometric method was applied for rapid determination of chlorophylls, carotenoids and pheophytins; as degradation products of chlorophylls. High Performance Thin-Layer Chromatography (HPTLC) was used for effective separation of these compounds, and also Atomic Absorption Spectrometry for determination of heavy metals as indicator of environmental pollution. Based on the results obtained from UV-vis spectrophotometric determination of photosynthetic pigments (chlorophylls and carotenoids), it was confirmed that Chlorella vulgaris contains more of all these pigments compared to the cyanobacteria Spirulina platensis. The fastest mobility compound identified in Chlorella vulgaris and Spirulina platensis using HPTLC method was β-carotene. Spectral analysis and standard calibration curve method were used for identification and quantification of separated substances on Thin-Layer Chromatographic plate. Quantification of copper (Cu 2+ , at 324.7 nm) and zinc (Zn 2+ , at 213.9nm) was performed using Flame Atomic Absorption Spectrometry with air-acetylene flame atomization. Quantification of cadmium (Cd 2+ , at 228.8 nm), nickel (Ni 2+ , at 232.0nm) and lead (Pb 2+ , at 283.3nm) by Electrothermal Graphite Furnace Atomic Absorption Spectrometry; and quantification of mercury (Hg 2+ , at 254nm) by Cold Vapour Atomic Absorption Spectrometry. Copyright © 2017 Elsevier B.V. All rights reserved.

Liquid chromatography-hydride generation-atomic absorption spectrometry for the speciation of tin in seafoods.

PubMed

Viñas, Pilar; López-García, Ignacio; Merino-Meroño, Beatriz; Campillo, Natalia; Hernández-Cordóba, Manuel

2004-04-01

Liquid chromatography with hydride generation atomic absorption spectrometry as the detection system was applied to the separation and determination of inorganic tin, tributyltin, dibutyltin, monobutyltin, diphenyltin and monophenyltin. A reversed phase C18 column and a methanol/water/acetic acid (70:27:3, v/v/v) mixture containing 0.05%(v/v) triethylamine and 0.1%(w/v) tropolone as the mobile phase (isocratic elution) were used. Extraction of organotins from the samples was carried out using methanol containing 0.05%(w/v) tropolone, a process that was repeated twice. The supernatants were shaken with water and dichloromethane in a separating funnel and the organic phase was collected and evaporated to dryness. When the method was applied to the speciation of tin in fresh and canned mussels, no organotins above the detection limits were identified in any of the samples, inorganic tin being the only species detected. The reliability of the procedure was checked by analyzing the total tin content of the samples by electrothermal atomic absorption spectrometry and by speciation of tin in a certified reference material, mussel tissue (CRM 477). The method can be used for environmental monitoring of organotins contaminated samples.

Magnetic ferrite particles combined with electrothermal atomic absorption spectrometry for the speciation of low concentrations of arsenic.

PubMed

López-García, Ignacio; Marín-Hernández, Juan José; Hernández-Córdoba, Manuel

2018-05-01

Freshly in situ prepared ferrite particles were used for the micro-solid phase extraction of arsenic species. When the separation was carried out at pH 8, inorganic arsenic (As(III) + As(V)) and monomethylarsonic acid (MMA) were retained in the magnetic material. A second aliquot was treated with 2,3 dimercapto propanol, leading to the retention of As(V)+MMA, while a third aliquot was first treated with sodium thiosulphate, in which case only inorganic arsenic passed to the solid phase. In all cases, the solid residue collected by a magnet was suspended in a dilute nitric acid solution containing Triton X-100 and introduced into the electrothermal atomizer to obtain the analytical signal of arsenic. The use of palladium as a chemical modifier allowed calibration to be carried out with aqueous standards. The detection limit was 0.02µgL -1 arsenic for a 10mL sample volume. The procedure was applied to waters and herbal infusions, and its reliability was evaluated by analyzing eleven certified reference materials for which speciation data are provided. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of palladium and zirconium treated graphite tubes for in-atomizer trapping of hydrogen selenide in hydride generation electrothermal atomization atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Laborda, Francisco; Medrano, Jesús; Cortés, José I.; Mir, José M.; Castillo, Juan R.

1999-02-01

Zirconium treated graphite tubes were investigated and compared with non-treated and palladium coated ones for in situ trapping of selenium hydride generated in a flow injection system. Selenium was effectively trapped on zirconium treated tubes at trapping temperatures of 300-600°C, similar to those observed for palladium, whereas trapping temperatures higher than 600°C had to be used with non-treated tubes. Zirconium treated tubes used in this work showed good stability up to 300 trapping/atomization cycles, with precision better than 5%, characteristic masses of 42 (peak height) and 133 pg (peak area) of selenium were obtained. Sensitivity of zirconium and palladium treatments were similar, but zirconium offered the advantage of a single application per tube. Detection limits were 0.11 (peak height) and 0.23 ng (peak area) for a 1 ml sample volume.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gregoire, D.C.; Goltz, D.M.; Chakrabarti, C.L.

Graphite furnace atomic absorption spectrometry (GFAAS) is an insensitive technique for determination of uranium. Experiments were conducted using electrothermal vaporization inductively coupled plasma mass spectrometry to investigate the atomization and vaporization of atomic and molecular uranium species in the graphite furnace. ETV-ICP-MS signals for uranium were observed at temperatures well below the appearance temperature of uranium atoms suggesting the vaporization of molecular uranium oxide at temperatures below 2000{degrees}C. Examination of individual uranium ETV-ICP-MS signals reveals the vaporization of uranium carbide at temperatures above 2600{degrees}C. Chemical modifiers such as 0.2% HF and 0.1% CHF{sub 3} in the argon carrier gas, weremore » ineffective in preventing the formation of uranium carbide at 2700{degrees}C. Vaporization of uranium from a tungsten surface using tungsten foil inserted into the graphite tube prevented the formation of uranium carbide and eliminated the ETV-ICP-MS signal suppression caused by a sodium chloride matrix.« less

Determination of trace elements in automotive fuels by filter furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Anselmi, Anna; Tittarelli, Paolo; Katskov, Dmitri A.

2002-03-01

The determination of Cd, Cr, Cu, Pb and Ni was performed in gasoline and diesel fuel samples by electrothermal atomic absorption spectrometry using the Transverse Heated Filter Atomizer (THFA). Thermal conditions were experimentally defined for the investigated elements. The elements were analyzed without addition of chemical modifiers, using organometallic standards for the calibration. Forty-microliter samples were injected into the THFA. Gasoline samples were analyzed directly, while diesel fuel samples were diluted 1:4 with n-heptane. The following characteristic masses were obtained: 0.8 pg Cd, 6.4 pg Cr, 12 pg Cu, 17 pg Pb and 27 pg Ni. The limits of determination for gasoline samples were 0.13 μg/kg Cd, 0.4 μg/kg Cr, 0.9 μg/kg Cu, 1.5 μg/kg Pb and 2.5 μg/kg Ni. The corresponding limit of determination for diesel fuel samples was approximately four times higher for all elements. The element recovery was performed using the addition of organometallic compounds to gasoline and diesel fuel samples and was between 85 and 105% for all elements investigated.

Comparison of colorimetry and electrothermal atomic absorption spectroscopy for the quantification of non-transferrin bound iron in human sera.

PubMed

Jittangprasert, Piyada; Wilairat, Prapin; Pootrakul, Pensri

2004-12-01

This paper describes a comparison of two analytical techniques, one employing bathophenanthrolinedisulfonate (BPT), a most commonly-used reagent for Fe (II) determination, as chromogen and an electrothermal atomic absorption spectroscopy (ETAAS) for the quantification of non-transferrin bound iron (NTBI) in sera from thalassemic patients. Nitrilotriacetic acid (NTA) was employed as the ligand for binding iron from low molecular weight iron complexes present in the serum but without removing iron from the transferrin protein. After ultrafiltration the Fe (III)-NTA complex was then quantified by both methods. Kinetic study of the rate of the Fe (II)-BPT complex formation for various excess amounts of NTA ligand was also carried out. The kinetic data show that a minimum time duration (> 60 minutes) is necessary for complete complex formation when large excess of NTA is used. Calibration curves given by colorimetric and ETAAS methods were linear over the range of 0.15-20 microM iron (III). The colorimetric and ETAAS methods exhibited detection limit (3sigma) of 0.13 and 0.14 microM, respectively. The NTBI concentrations from 55 thalassemic serum samples measured employing BPT as chromogen were statistically compared with the results determined by ETAAS. No significant disagreement at 95% confidence level was observed. It is, therefore, possible to select any one of these two techniques for determination of NTBI in serum samples of thalassemic patients. However, the colorimetric procedure requires a longer analysis time because of a slow rate of exchange of NTA ligand with BPT, leading to the slow rate of formation of the colored complex.

Development of new portable miniaturize solid phase microextraction of silver-APDC complex using micropipette tip in-syringe system couple with electrothermal atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Naeemullah; Kazi, Tasneem Gul; Afridi, Hassan Imran; Shah, Faheem; Arain, Sadaf Sadia; Arain, Salma Aslam; Panhwar, Abdul Haleem; Arain, Mariam Shahzadi; Samoon, Muhammad Kashif

2016-02-01

An innovative and simple miniaturized solid phase microextraction (M-SPME) method, was developed for preconcentration and determination of silver(I) in the fresh and waste water samples. For M-SPME, a micropipette tip packed with activated carbon cloth (ACC) as sorbent, in a syringe system. The size, morphology and elemental composition of ACC before and after adsorption of analyte have been characterized by scanning electron microscopy and energy dispersive spectroscopy. The sample solution treated with a complexing reagent, ammonium pyrrolidine dithiocarbamate (APDC), was drawn into the syringe filled with ACC and dispensed manually for 2 to 10 aspirating/dispensing cycle. Then the Ag- complex sorbed on the ACC in micropipette was quantitatively eluted by drawing and dispensing of different concentrations of acids for 2 to 5 aspirating/dispensing cycles. The extracted Ag ions with modifier were injected directly into the electrothermal atomic absorption spectrometry for analysis. The influence of different variables on the extraction efficiency, including the concentration of ligand, pH, sample volume, eluent type, concentration and volume was investigated. Validity and accuracy of the developed method was checked by the standard addition method. Reliability of the proposed methodology was checked by the relative standard deviation (%RSD), which was found to be < 5%. Under the optimized experimental variables, the limits of detection (LOD) and enhancement factors (EF), were obtained to be 0.86 ng L- 1 and 120, respectively. The proposed method was successfully applied for the determination of trace levels of silver ions in fresh and waste water samples.

Selective and sensitive speciation analysis of Cr(VI) and Cr(III), at sub-μgL-1 levels in water samples by electrothermal atomic absorption spectrometry after electromembrane extraction.

PubMed

Tahmasebi, Zeinab; Davarani, Saied Saeed Hosseiny

2016-12-01

In this work, electromembrane extraction in combination with electrothermal atomic absorption spectrometry (ET-AAS) was investigated for speciation, preconcentration and quantification of Cr(VI) and Cr(III) in water samples through the selective complexation of Cr(VI) with 1,5-diphenylcarbazide (DPC) as a complexing agent. DPC reduces Cr(VI) to Cr(III) ions and then Cr(III) species are extracted based on electrokinetic migration of their cationic complex (Cr(III)-DPC) toward the negative electrode placed in the hollow fiber. Also, once oxidized to Cr(VI), Cr(III) ions in initial sample were determined by this procedure. The influence of extraction parameters such as pH, type of organic solvent, chelating agent concentration, stirring rate, extraction time and applied voltage were evaluated following a one-at-a-time optimization approach. Under optimized conditions, the extracted analyte was quantified by ETAAS, with an acceptable linearity in the range of 0.05-5ngmL -1 (R 2 value=0.996), and a repeatability (%RSD) between 3.7% and 12.2% (n=4) for 5.0 and 1.0ngmL -1 of Cr(VI), respectively. Also, we obtained an enrichment factor of 110 that corresponded to the recovery of 66%. The detection limit (S/N ratio of 3:1) was 0.02ngmL -1 . Finally, this new method was successfully employed to determine Cr(III) and Cr(VI) species in real water samples. Copyright © 2016. Published by Elsevier B.V.

Organic palladium and palladium-magnesium chemical modifiers in direct determination of lead in fractions from distillation of crude oil by electrothermal atomic absorption analysis

NASA Astrophysics Data System (ADS)

Kowalewska, Zofia; Bulska, Ewa; Hulanicki, Adam

1999-05-01

Platinum reforming catalysts are easily poisoned by increased levels of lead, therefore a sensitive atomic absorption spectrometric procedure for lead determination in fractions from crude oil distillation was developed. Lead was present in organic form in the samples analysed therefore the behaviour of various lead compounds (Pb-alkylarylsulphonate, Pb-4-cyclohexanobutyrate, tetraethyllead, Pb in fuel oil) was studied. The best procedure for the determination of lead in different petroleum products, including those containing asphaltenes includes a pretreatment with iodine and methyltrioctylammonium chloride, followed by the use of an organic Pd-Mg modifier. Under these conditions an effective matrix removal is possible at a pyrolysis temperature up to approximately 1100°C and the behaviour of lead present in different forms is unified. The characteristic mass is 11-12 pg Pb, corresponding to a detection limit of 0.25 ng g -1 for 20 μl sample solution. This can be lowered by multiple injection.

Investigation of Industrial Polyurethane Foams Modified with Antimicrobial Copper Nanoparticles

PubMed Central

Sportelli, Maria Chiara; Picca, Rosaria Anna; Ronco, Roberto; Bonerba, Elisabetta; Tantillo, Giuseppina; Pollini, Mauro; Sannino, Alessandro; Valentini, Antonio; Cataldi, Tommaso R.I.; Cioffi, Nicola

2016-01-01

Antimicrobial copper nanoparticles (CuNPs) were electrosynthetized and applied to the controlled impregnation of industrial polyurethane foams used as padding in the textile production or as filters for air conditioning systems. CuNP-modified materials were investigated and characterized morphologically and spectroscopically, by means of Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). The release of copper ions in solution was studied by Electro-Thermal Atomic Absorption Spectroscopy (ETAAS). Finally, the antimicrobial activity of freshly prepared, as well as aged samples—stored for two months—was demonstrated towards different target microorganisms. PMID:28773665

Method development for the determination of fluorine in water samples via the molecular absorption of strontium monofluoride formed in an electrothermal atomizer

NASA Astrophysics Data System (ADS)

Ozbek, Nil; Akman, Suleyman

The presence of fluorine (F) was detected via the rotational molecular absorption line of diatomic strontium-monofluoride (SrF) generated in the gas phase at 651.187 nm using high-resolution continuum source electrothermal atomic absorption spectrometry. Upon the addition of excess strontium (Sr) as the nitrate, the fluorine in the sample was converted to SrF in the gas phase of a graphite furnace. The effects on the accuracy, precision and sensitivity of variables such as the SrF wavelength, graphite furnace program, amount of Sr, coating of the graphite tube and platform with Zr and Ir and the use of a modifier were investigated and optimized. It was determined that there was no need to use a modifier or to cover the platform/tubes with Zr or Ir. Fluorine concentrations in various water samples (certified waste water, tap water, drinking water and mineral water) were determined using 20 μg of Sr as the molecule-forming reagent and applying a maximum pyrolysis temperature of 800 °C and a molecule-forming temperature of 2200 °C with a heating rate of 2000 °C s- 1. Good linearity was maintained up to 0.1 μg of F. The accuracy and precision of the method were tested by analyzing certified reference wastewater. The results were in good agreement with certified values, and the precision was satisfactory (RSD < 10%). The limit of detection and the characteristic mass for the method were 0.36 ng and 0.55 ng, respectively. Finally, the fluorine concentrations in several drinking water and mineral water samples taken from the market were determined. The results were in good agreement with the values supplied by the producers. No significant differences were found between the results from the linear calibration and standard addition techniques. The method was determined to be simple, fast, accurate and sensitive.

Determination of indium in geological materials by electrothermal-atomization atomic absorption spectrometry with a tungsten-impregnated graphite furance

USGS Publications Warehouse

Zhou, L.; Chao, T.T.; Meier, A.L.

1984-01-01

The sample is fused with lithium metaborate and the melt is dissolved in 15% (v/v) hydrobromic acid. Iron(III) is reduced with ascorbic acid to avoid its coextraction with indium as the bromide into methyl isobutyl ketone. Impregnation of the graphite furnace with sodium tungstate, and the presence of lithium metaborate and ascorbic acid in the reaction medium improve the sensitivity and precision. The limits of determination are 0.025-16 mg kg-1 indium in the sample. For 22 geological reference samples containing more than 0.1 mg kg-1 indium, relative standard deviations ranged from 3.0 to 8.5% (average 5.7%). Recoveries of indium added to various samples ranged from 96.7 to 105.6% (average 100.2%). ?? 1984.

Direct determination of chromium in infant formulas employing high-resolution continuum source electrothermal atomic absorption spectrometry and solid sample analysis.

PubMed

Silva, Arlene S; Brandao, Geovani C; Matos, Geraldo D; Ferreira, Sergio L C

2015-11-01

The present work proposed an analytical method for the direct determination of chromium in infant formulas employing the high-resolution continuum source electrothermal atomic absorption spectrometry combined with the solid sample analysis (SS-HR-CS ET AAS). Sample masses up to 2.0mg were directly weighted on a solid sampling platform and introduced into the graphite tube. In order to minimize the formation of carbonaceous residues and to improve the contact of the modifier solution with the solid sample, a volume of 10 µL of a solution containing 6% (v/v) H2O2, 20% (v/v) ethanol and 1% (v/v) HNO3 was added. The pyrolysis and atomization temperatures established were 1600 and 2400 °C, respectively, using magnesium as chemical modifier. The calibration technique was evaluated by comparing the slopes of calibration curves established using aqueous and solid standards. This test revealed that chromium can be determined employing the external calibration technique using aqueous standards. Under these conditions, the method developed allows the direct determination of chromium with limit of quantification of 11.5 ng g(-1), precision expressed as relative standard deviation (RSD) in the range of 4.0-17.9% (n=3) and a characteristic mass of 1.2 pg of chromium. The accuracy was confirmed by analysis of a certified reference material of tomato leaves furnished by National Institute of Standards and Technology. The method proposed was applied for the determination of chromium in five different infant formula samples. The chromium content found varied in the range of 33.9-58.1 ng g(-1) (n=3). These samples were also analyzed employing ICP-MS. A statistical test demonstrated that there is no significant difference between the results found by two methods. The chromium concentrations achieved are lower than the maximum limit permissible for chromium in foods by Brazilian Legislation. Copyright © 2015. Published by Elsevier B.V.

Slurry sampling high-resolution continuum source electrothermal atomic absorption spectrometry for direct beryllium determination in soil and sediment samples after elimination of SiO interference by least-squares background correction.

PubMed

Husáková, Lenka; Urbanová, Iva; Šafránková, Michaela; Šídová, Tereza

2017-12-01

In this work a simple, efficient, and environmentally-friendly method is proposed for determination of Be in soil and sediment samples employing slurry sampling and high-resolution continuum source electrothermal atomic absorption spectrometry (HR-CS-ETAAS). The spectral effects originating from SiO species were identified and successfully corrected by means of a mathematical correction algorithm. Fractional factorial design has been employed to assess the parameters affecting the analytical results and especially to help in the development of the slurry preparation and optimization of measuring conditions. The effects of seven analytical variables including particle size, concentration of glycerol and HNO 3 for stabilization and analyte extraction, respectively, the effect of ultrasonic agitation for slurry homogenization, concentration of chemical modifier, pyrolysis and atomization temperature were investigated by a 2 7-3 replicate (n = 3) design. Using the optimized experimental conditions, the proposed method allowed the determination of Be with a detection limit being 0.016mgkg -1 and characteristic mass 1.3pg. Optimum results were obtained after preparing the slurries by weighing 100mg of a sample with particle size < 54µm and adding 25mL of 20% w/w glycerol. The use of 1μg Rh and 50μg citric acid was found satisfactory for the analyte stabilization. Accurate data were obtained with the use of matrix-free calibration. The accuracy of the method was confirmed by analysis of two certified reference materials (NIST SRM 2702 Inorganics in Marine Sediment and IGI BIL-1 Baikal Bottom Silt) and by comparison of the results obtained for ten real samples by slurry sampling with those determined after microwave-assisted extraction by inductively coupled plasma time of flight mass spectrometry (TOF-ICP-MS). The reported method has a precision better than 7%. Copyright © 2017 Elsevier B.V. All rights reserved.

Speciation and determination of ultra trace amounts of inorganic tellurium in environmental water samples by dispersive liquid-liquid microextraction and electrothermal atomic absorption spectrometry.

PubMed

Najafi, Nahid Mashkouri; Tavakoli, Hamed; Alizadeh, Reza; Seidi, Shahram

2010-06-18

A simple and powerful method has been developed for the rapid and selective determination of Te(IV) and Te(VI), employing dispersive liquid-liquid microextraction combined with electrothermal atomic absorption spectrometry using palladium as permanent modifier. Under acidic conditions pH 1, only Te(IV) can form a complex with ammonium pyrrolidine dithiocarbamate (APDC) and therefore be extracted into fine droplets of carbon tetrachloride (extraction solvent) which are dispersed with ethanol into the water sample solution. After centrifugation, Te(IV) was determined in the sedimented organic phase while Te(VI) remained in the aqueous phase. Total inorganic tellurium was determined after the reduction of the Te(VI) to Te(IV). Te(VI) was calculated as the difference between the measured total inorganic tellurium and Te(IV) content. The effective parameters for improving the efficiency of microextraction process were investigated by using experimental and central composite designs. Under optimal conditions the enrichment factor was 125 and the calibration graph was linear in the range of 0.015-1 ng mL(-1) with detection limit and characteristic mass of 0.004 ng mL(-1) and 0.033 pg, respectively. The relative standard deviation for 0.5 ng mL(-1) of tellurium measurement was 3.6% (n=6) at ash and atomization temperature, 900 and 2600 degrees C, respectively. The recoveries of spiked Te(IV) and Te(VI) to the environmental water samples were 89.6-101.3% and 96.6-99.1%, respectively. The accuracy is also evaluated by applying the proposed method to certified reference material (NIST SRM 1643e), for which the result was in a good agreement with the certified values reported for this CRM (95% confidence level). 2010 Elsevier B.V. All rights reserved.

A new supramolecular based liquid solid microextraction method for preconcentration and determination of trace bismuth in human blood serum and hair samples by electrothermal atomic absorption spectrometry.

PubMed

Kahe, Hadi; Chamsaz, Mahmoud

2016-11-01

A simple and reliable supramolecule-aggregated liquid solid microextraction method is described for preconcentration and determination of trace amounts of bismuth in water as well as human blood serum and hair samples. Catanionic microstructures of cetyltrimethylammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) surfactants, dissolved in deionized water/propanol, are used as a green solvent to extract bismuth (III)-diethyldithiocarbamate complexes by dispersive microextraction methodology. The extracted solid phase is easily removed and dissolved in 50 μL propanol for subsequent measurement by electrothermal atomic absorption spectrometry (ET-AAS). The procedure benefits the merits of supramolecule aggregates' properties and dispersive microextraction technique using water as the main component of disperser solvent, leading to direct interaction with analyte. Phase separation behavior of extraction solvent and different parameters influencing the extraction efficiency of bismuth ion such as salt concentration, pH, centrifugation time, amount of chelating agent, SDS:CTAB mole ratio, and solvent amounts were thoroughly optimized. Under the optimal experimental conditions, the calibration curve was linear in the range of 0.3-6 μg L -1 Bi (III) with a limit of detection (LOD) of 0.16 μg L -1 (S/N = 3). The relative standard deviations (RSD) of determination were obtained to be 5.1 and 6.2 % for 1 and 3 μg L -1 of Bi (III), respectively. The developed method was successfully applied as a sensitive and accurate technique for determination of bismuth ion in human blood serum, hair samples, and a certified reference material.

Liquid chromatography-electrothermal atomic absorption spectrometry for the separation and preconcentration of molybdenum in milk and infant formulas.

PubMed

López-García, I; Viñas, P; Romero-Romero, R; Hernández-Córdoba, M

2007-08-06

Two procedures for the electrothermal atomic absorption spectrometric determination of molybdenum in milk and infant formulas using slurried samples are described. For powdered milk samples, 10% (m/v) slurries were prepared in a medium containing 25 and 75% (v/v) concentrated hydrogen peroxide and hydrofluoric acid, respectively, and introduced directly into the furnace. Palladium (200 microg mL(-1)) was used as the modifier and calibration was carried out using aqueous standards prepared in the same medium. The detection limit was 0.02 microg g(-1) for powdered milk samples suspended at 10% (m/v) (equivalent to 2 microg L(-1)). The relative standard deviation (R.S.D.) for five measurements was 1.9%, the characteristic mass being 25 pg. For liquid milk samples, a procedure was proposed based on preconcentration and removal of the matrix, using ionic exchange (Amberlite IRA 743) and elution of molybdenum with 5% (m/v) NaOH. In this case, a 30-fold improvement in the calibration slope was achieved, leading to a detection limit of 0.04 microg L(-1) for liquid samples diluted to 10%. The R.S.D. was 3.5%. Using a size-based separation procedure, it was found that molybdenum is present in its inorganic form or associated to low molecular weight substances in cow milk, while in breast milk it is associated to proteins. The reliability of the procedure was checked by comparing the results obtained with those found using a previous mineralization stage and by analyzing three certified reference materials, namely, BCR 063R (skim milk powder), NBS 1549 (non-fat milk powder) and NBS 8435 (whole milk powder).

Development of new portable miniaturize solid phase microextraction of silver-APDC complex using micropipette tip in-syringe system couple with electrothermal atomic absorption spectrometry.

PubMed

Naeemullah; Kazi, Tasneem Gul; Afridi, Hassan Imran; Shah, Faheem; Arain, Sadaf Sadia; Arain, Salma Aslam; Panhwar, Abdul Haleem; Arain, Mariam Shahzadi; Samoon, Muhammad Kashif

2016-02-05

An innovative and simple miniaturized solid phase microextraction (M-SPME) method, was developed for preconcentration and determination of silver(I) in the fresh and waste water samples. For M-SPME, a micropipette tip packed with activated carbon cloth (ACC) as sorbent, in a syringe system. The size, morphology and elemental composition of ACC before and after adsorption of analyte have been characterized by scanning electron microscopy and energy dispersive spectroscopy. The sample solution treated with a complexing reagent, ammonium pyrrolidine dithiocarbamate (APDC), was drawn into the syringe filled with ACC and dispensed manually for 2 to 10 aspirating/dispensing cycle. Then the Ag- complex sorbed on the ACC in micropipette was quantitatively eluted by drawing and dispensing of different concentrations of acids for 2 to 5 aspirating/dispensing cycles. The extracted Ag ions with modifier were injected directly into the electrothermal atomic absorption spectrometry for analysis. The influence of different variables on the extraction efficiency, including the concentration of ligand, pH, sample volume, eluent type, concentration and volume was investigated. Validity and accuracy of the developed method was checked by the standard addition method. Reliability of the proposed methodology was checked by the relative standard deviation (%RSD), which was found to be <5%. Under the optimized experimental variables, the limits of detection (LOD) and enhancement factors (EF), were obtained to be 0.86 ng L(-1) and 120, respectively. The proposed method was successfully applied for the determination of trace levels of silver ions in fresh and waste water samples. Copyright © 2015 Elsevier B.V. All rights reserved.

[Exposure to metal compounds in occupational galvanic processes].

PubMed

Surgiewicz, Jolanta; Domański, Wojciech

2006-01-01

Occupational galvanic processes are provided in more than 600 small and medium enterprises in Poland. Workers who deal with galvanic coating are exposed to heavy metal compounds: tin, silver, copper and zinc. Some of them are carcinogenic, for example, hexavalent chromium compounds, nickel and cadmium compounds. Research covered several tens of workstations involved in chrome, nickel, zinc, tin, silver, copper and cadmium plating. Compounds of metals present in the air were determined: Cr, Ni, Cd, Sn, Ag--by atomic absorption spectrometry with electrothermal atomization (ET-AAS) and Zn--by atomic absorption spectrometry with flame atomization (F-AAS). The biggest metal concentrations--of silver and copper--were found at workstations of copper, brass, cadmium, nickel and chrome plating, conducted at the same time. Significant concentrations of copper were found at workstations of maintenance bathing and neutralizing of sewage. The concentrations of metals did not exceed Polish MAC values. MAC values were not exceeded for carcinogenic chromium(VI), nickel or cadmium, either. In galvanic processes there was no hazard related to single metals or their compounds, even carcinogenic ones. Combined exposure indicators for metals at each workstation did not exceed 1, either. However, if there are even small quantities of carcinogenic agents, health results should always be taken into consideration.

Tear copper and its association with liver copper concentrations in six adult ewes.

PubMed Central

Schoster, J V; Stuhr, C; Kiorpes, A

1995-01-01

Tear and liver copper concentrations from 6 clinically healthy adult mixed-breed ewes were measured by Atomic Absorption Electrothermal Atomization (graphite furnace) Spectrometry and Flame Absorption Spectrometry, respectively, 7 times over 227 d to determine if their tears contained copper and if so, whether tear copper concentrations could reliably predict liver copper concentrations. To produce changes in liver copper concentration, the diet was supplemented with copper at concentrations that increased from 23 mg to 45 mg Cu/kg feed/day/sheep during the study. This regimen raised liver copper for all sheep to potentially toxic hepatic tissue concentration of greater than 500 mg/kg dry (DM) matter (tissue). The results of the study showed that copper was present in the tears of all sheep. The mean tear copper concentration showed a positive correlation with liver copper concentration (P = 0.003), increasing from 0.07 mg/kg DM at the start to 0.44 mg/kg DM at the end of the study, but could not reliably predict liver copper concentration (R2 = 0.222). PMID:7648525

Determination of cadmium and lead at low levels by using preconcentration at fullerene coupled to thermospray flame furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Pereira, M. G.; Pereira-Filho, E. R.; Berndt, H.; Arruda, M. A. Z.

2004-04-01

A new and sensitive method for Cd and Pb determinations, based on the coupling of thermospray flame furnace atomic absorption spectrometry and a preconcentrator system, was developed. The procedure comprised the chelating of Cd and Pb with ammonium pyrrolidinedithiocarbamate with posterior adsorption of the chelates on a mixture (40 mg) of C 60 and C 70 at a flow rate of 2.0 ml min -1. These chelates were eluted from the adsorbent by passing a continuous flow of ethanol (80% v/v) at 0.9 ml min -1 to a nickel tube placed in an air/acetylene flame. After sample introduction into the tube by using a ceramic capillary (0.5 mm i.d.), the analytical signals were registered as peak height. Under these conditions, improvement factors in detectability of 675 and 200 were obtained for Cd and Pb, respectively, when compared to conventional flame atomic absorption spectrometry. Spiked samples (mineral and tap waters) and drinking water containing natural concentrations of Cd were employed for evaluating accuracy by comparing the results obtained from the proposed methodology with those using electrothermal atomic absorption spectrometry. In addition, certified reference materials (rye grass, CRM 281 and pig kidney, CRM 186) were also adopted for the accuracy tests. Due to the good linearity ranges for Cd (0.5-5.0 μg l -1) and Pb (10-250 μg l -1), samples with different concentrations could be analyzed. Detection limits of 0.1 and 2.4 μg l -1 were obtained for Cd and Pb, respectively, and RSD values <4.5% were observed ( n=10). Finally, a sample throughput of 24 determinations per hour was possible.

In-situ pre-concentration through repeated sampling and pyrolysis for ultrasensitive determination of thallium in drinking water by electrothermal atomic absorption spectrometry.

PubMed

Liu, Liwei; Zheng, Huaili; Xu, Bincheng; Xiao, Lang; Chigan, Yong; Zhangluo, Yilan

2018-03-01

In this paper, a procedure for in-situ pre-concentration in graphite furnace by repeated sampling and pyrolysis is proposed for the determination of ultra-trace thallium in drinking water by graphite furnace atomic absorption spectrometry (GF-AAS). Without any other laborious enrichment processes that routinely result in analyte loss and contamination, thallium was directly concentrated in the graphite furnace automatically and subsequently subject to analysis. The effects of several key factors, such as the temperature for pyrolysis and atomization, the chemical modifier, and the repeated sampling times were investigated. Under the optimized conditions, a limit of detection of 0.01µgL -1 was obtained, which fulfilled thallium determination in drinking water by GB 5749-2006 regulated by China. Successful analysis of thallium in certified water samples and drinking water samples was demonstrated, with analytical results in good agreement with the certified values and those by inductively coupled plasma mass spectrometry (ICP-MS), respectively. Routine spike-recovery tests with randomly selected drinking water samples showed satisfactory results of 80-96%. The proposed method is simple and sensitive for screening of ultra-trace thallium in drinking water samples. Copyright © 2017. Published by Elsevier B.V.

On-line ionic liquid-based preconcentration system coupled to flame atomic absorption spectrometry for trace cadmium determination in plastic food packaging materials.

PubMed

Martinis, Estefanía M; Olsina, Roberto A; Altamirano, Jorgelina C; Wuilloud, Rodolfo G

2009-05-15

A novel on-line preconcentration method based on liquid-liquid (L-L) extraction with room temperature ionic liquids (RTILs) coupled to flame atomic absorption spectrometry (FAAS) was developed for cadmium determination in plastic food packaging materials. The methodology is based on the complexation of Cd with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) reagent after sample digestion followed by extraction of the complex with the RTIL 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF(6)]). The mixture was loaded into a flow injection analysis (FIA) manifold and the RTIL rich-phase was retained in a microcolumn filled with silica gel. The RTIL rich-phase was then eluted directly into FAAS. A enhancement factor of 35 was achieved with 20 mL of sample. The limit of detection (LOD), obtained as IUPAC recommendation, was 6 ng g(-1) and the relative standard deviation (R.S.D.) for 10 replicates at 10 microg L(-1) Cd concentration level was 3.9%, calculated at the peak heights. The calibration graph was linear and a correlation coefficient of 0.9998 was achieved. The accuracy of the method was evaluated by both a recovery study and comparison of results with direct determination by electrothermal atomic absorption spectrometry (ETAAS). The method was successfully applied for Cd determination in plastic food packaging materials and Cd concentrations found were in the range of 0.04-10.4 microg g(-1).

Comparison of lead and cadmium contents in cruciferous vegetables grown under diversified ecological conditions: Cracow region of Poland.

PubMed

Kapusta-Duch, Joanna; Leszczyńska, Teresa; Florkiewicz, Adam; Filipiak-Florkiewicz, Agnieszka

2011-01-01

The aim of the present study was to compare lead and cadmium contents in cruciferous vegetables grown under diversified ecological conditions for three consecutive years, independently of the climatic and agrotechnical conditions. The research was conducted in the Cracow region of Poland and tests vegetables near the Steelworks, from ecological farms, and from local markets. The heavy metal contents were determined using the validated Atomic Absorption Spectrometry method, including electrothermal atomization, with an ET-AAS graphite cuvette (Varian AA240Z, made by Varian). Cruciferous vegetables cultivated in the areas surrounding the steelworks were characterized by alarmingly high lead content versus ecological and commercially available vegetables, while the contents of this metal in vegetables from the two latter locations did not differ. It cannot be definitively stated that the origin of vegetables influenced their cadmium content.

Pulsed electrothermal thruster

NASA Technical Reports Server (NTRS)

Burton, Rodney L. (Inventor); Goldstein, Yeshayahu S. A. (Inventor); Tidman, Derek A. (Inventor); Winsor, Niels K. (Inventor)

1989-01-01

A plasma electrothermal thruster includes a capillary passage in which a plasma discharge is formed and directed out of an open end of the passage into a supersonic nozzle. Liquid supplied to the capillary passage becomes partially atomized to cool a confining surface of the passage. The plasma discharge is formed as the atomized liquid flows out of the open end into a supersonic equilibrium nozzle. The discharge can have a duration greater than the two way travel time of acoustic energy in the capillary to cause the plasma to flow continuously through the nozzle during the time of the discharge pulse.

Laser-Excited Atomic Fluorescence and Ionization in a Graphite Furnace for the Determination of Metals and Nonmetals

NASA Astrophysics Data System (ADS)

Butcher, David James

1990-01-01

Here is reported novel instrumentation for atomic spectrometry that combined the use of a pulsed laser system as the light source and an electrothermal atomizer as the atom cell. The main goal of the research was to develop instrumentation that was more sensitive for elemental analysis than commercially available instruments and could be used to determine elements in real sample matrices. Laser excited atomic fluorescence spectrometry (LEAFS) in an electrothermal atomizer (ETA) was compared to ETA atomic absorption spectrometry (AAS) for the determination of thallium, manganese, and lead in food and agricultural standard reference materials (SRMs). Compared to ETA AAS, ETA LEAFS has a longer linear dynamic range (LDR) (5-7 orders of magnitude compared to 2-3 orders of magnitude) and higher sensitivity (10 ^{-16} to 10^{ -14} g as compared to 10^{ -13} to 10^{-11} g). Consequently, ETA LEAFS allows elemental analysis to be done over a wider range of concentrations with less dilution steps. Thallium was accurately determined in biological samples by ETA LEAFS at amounts five to one hundred times below the ETA AAS detection limit. ETA AAS and ETA LEAFS were compared for the determination of lead and manganese, and in general, the accuracies and precisions of ETA AAS were the same, with typical precisions between 3% and 6%. Fluorine was determined using laser excited molecular fluorescence spectrometry (LEMOFS) in an ETA. Molecular fluorescence from magnesium fluoride was collected, and the detection limit of 0.3 pg fluorine was two to six orders of magnitude more sensitive than other methods commonly used for the determination of fluorine. Significant interferences from ions were observed, but the sensitivity was high enough that fluorine could be determined in freeze dried urine SRMs by diluting the samples by a factor of one hundred to remove the interferences. Laser enhanced ionization (LEI) in an ETA was used for the determination of metals. For thallium, indium, and lithium, detection limits between 0.7 and 2 pg were obtained, with an LDR of 3.5 orders of magnitude. Sodium was shown to severely depress the indium LEI signal in an ETA.

Highly selective micro-sequential injection lab-on-valve (muSI-LOV) method for the determination of ultra-trace concentrations of nickel in saline matrices using detection by electrothermal atomic absorption spectrometry.

PubMed

Long, Xiangbao; Miró, Manuel; Jensen, Rikard; Hansen, Elo Harald

2006-10-01

A highly selective procedure is proposed for the determination of ultra-trace level concentrations of nickel in saline aqueous matrices exploiting a micro-sequential injection Lab-On-Valve (muSI-LOV) sample pretreatment protocol comprising bead injection separation/pre-concentration and detection by electrothermal atomic absorption spectrometry (ETAAS). Based on the dimethylglyoxime (DMG) reaction used for nickel analysis, the sample, as contained in a pH 9.0 buffer, is, after on-line merging with the chelating reagent, transported to a reaction coil attached to one of the external ports of the LOV to assure sufficient reaction time for the formation of Ni(DMG)(2) chelate. The non-ionic coordination compound is then collected in a renewable micro-column packed with a reversed-phase copolymeric sorbent [namely, poly(divinylbenzene-co-N-vinylpyrrolidone)] containing a balanced ratio of hydrophilic and lipophilic monomers. Following elution by a 50-muL methanol plug in an air-segmented modality, the nickel is finally quantified by ETAAS. Under the optimized conditions and for a sample volume of 1.8 mL, a retention efficiency of 70 % and an enrichment factor of 25 were obtained. The proposed methodology showed a high tolerance to the commonly encountered alkaline earth matrix elements in environmental waters, that is, calcium and magnesium, and was successfully applied for the determination of nickel in an NIST standard reference material (NIST 1640-Trace elements in natural water), household tap water of high hardness and local seawater. Satisfying recoveries were achieved for all spiked environmental water samples with maximum deviations of 6 %. The experimental results for the standard reference material were not statistically different to the certified value at a significance level of 0.05.

Analysis of metal-laden water via portable X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Pearson, Delaina; Weindorf, David C.; Chakraborty, Somsubhra; Li, Bin; Koch, Jaco; Van Deventer, Piet; de Wet, Jandre; Kusi, Nana Yaw

2018-06-01

A rapid method for in-situ elemental composition analysis of metal-laden water would be indispensable for studying polluted water. Current analytical lab methods to determine water quality include flame atomic absorption spectrometry (FAAS), atomic absorption spectrophotometry (AAS), electrothermal atomic absorption spectrometry (EAAS), and inductively coupled plasma (ICP) spectroscopy. However only two field methods, colorimetry and absorptiometry, exist for elemental analysis of water. Portable X-ray fluorescence (PXRF) spectrometry is an effective method for elemental analysis of soil, sediment, and other matrices. However, the accuracy of PXRF is known to be affected while scanning moisture-laden soil samples. This study sought to statistically establish PXRF's predictive ability for various elements in water at different concentrations relative to inductively coupled plasma atomic emission spectroscopy (ICP-AES). A total of 390 metal-laden water samples collected from leaching columns of mine tailings in South Africa were analyzed via PXRF and ICP-AES. The PXRF showed differential effectiveness in elemental quantification. For the collected water samples, the best relationships between ICP and PXRF elemental data were obtained for K and Cu (R2 = 0.92). However, when scanning ICP calibration solutions with elements in isolation, PXRF results indicated near perfect agreement; Ca, K, Fe, Cu and Pb produced an R2 of 0.99 while Zn and Mn produced an R2 of 1.00. The utilization of multiple PXRF (stacked) beams produced stronger correlation to ICP relative to the use of a single beam in isolation. The results of this study demonstrated the PXRF's ability to satisfactorily predict the composition of metal-laden water as reported by ICP for several elements. Additionally this study indicated the need for a "Water Mode" calibration for the PXRF and demonstrates the potential of PXRF for future study of polluted or contaminated waters.

Determination of serum aluminum by electrothermal atomic absorption spectrometry: A comparison between Zeeman and continuum background correction systems

NASA Astrophysics Data System (ADS)

Kruger, Pamela C.; Parsons, Patrick J.

2007-03-01

Excessive exposure to aluminum (Al) can produce serious health consequences in people with impaired renal function, especially those undergoing hemodialysis. Al can accumulate in the brain and in bone, causing dialysis-related encephalopathy and renal osteodystrophy. Thus, dialysis patients are routinely monitored for Al overload, through measurement of their serum Al. Electrothermal atomic absorption spectrometry (ETAAS) is widely used for serum Al determination. Here, we assess the analytical performances of three ETAAS instruments, equipped with different background correction systems and heating arrangements, for the determination of serum Al. Specifically, we compare (1) a Perkin Elmer (PE) Model 3110 AAS, equipped with a longitudinally (end) heated graphite atomizer (HGA) and continuum-source (deuterium) background correction, with (2) a PE Model 4100ZL AAS equipped with a transversely heated graphite atomizer (THGA) and longitudinal Zeeman background correction, and (3) a PE Model Z5100 AAS equipped with a HGA and transverse Zeeman background correction. We were able to transfer the method for serum Al previously established for the Z5100 and 4100ZL instruments to the 3110, with only minor modifications. As with the Zeeman instruments, matrix-matched calibration was not required for the 3110 and, thus, aqueous calibration standards were used. However, the 309.3-nm line was chosen for analysis on the 3110 due to failure of the continuum background correction system at the 396.2-nm line. A small, seemingly insignificant overcorrection error was observed in the background channel on the 3110 instrument at the 309.3-nm line. On the 4100ZL, signal oscillation was observed in the atomization profile. The sensitivity, or characteristic mass ( m0), for Al at the 309.3-nm line on the 3110 AAS was found to be 12.1 ± 0.6 pg, compared to 16.1 ± 0.7 pg for the Z5100, and 23.3 ± 1.3 pg for the 4100ZL at the 396.2-nm line. However, the instrumental detection limits (3 SD) for Al were very similar: 3.0, 3.2, and 4.1 μg L - 1 for the Z5100, 4100ZL, and 3110, respectively. Serum Al method detection limits (3 SD) were 9.8, 6.9, and 7.3 μg L - 1 , respectively. Accuracy was assessed using archived serum (and plasma) reference materials from various external quality assessment schemes (EQAS). Values found with all three instruments were within the acceptable EQAS ranges. The data indicate that relatively modest ETAAS instrumentation equipped with continuum background correction is adequate for routine serum Al monitoring.

The energetics of hydrogen atom recombination - Analysis, experiments, and modeling. [in electrothermal propulsion system

NASA Technical Reports Server (NTRS)

Filpus, J. W.; Hawley, M. C.

1984-01-01

A theoretical investigation of the effect of the microscopic energetics of the recombination reaction on the performance of a microwave-plasma electrothermal propulsion system is described, and the results of the analysis are presented. A series of experiments to test the concept is described and analyzed by comparison with a computer model of the recombination reaction. It is concluded that internal energy considerations are not likely to significantly affect the design of a microwave-plasma electrothermal rocket. The experimental results indicate that the microwave power is far higher than the capacity of the gas to absorb it; the cooling needed to control the energy dominates the experimental results.

Lead levels in deciduous teeth of children in Bahrain.

PubMed

al-Mahroos, F; al-Saleh, F S

1997-06-01

To determine lead exposure among children in Bahrain, a total of 280 shed deciduous whole teeth were collected from 269 children. Teeth were analyzed for lead concentrations using atomic absorption spectrophotometry with electrothermal atomization. Children were between 5 and 15 years old. The study period extended from July 1993 to April 1994. The study showed that the overall mean tooth-lead level was 4.3 micrograms/g dry weight with a range of 0.1-60.8 micrograms/g dry weight. The cumulative frequency distribution revealed that 35% of the teeth had a lead concentration of more than 4 micrograms/g dry weight. The tooth-lead concentrations differed according to the tooth type age. The child's sex, nationality, area of residence and socio-economic status had no impact on tooth-lead level. In conclusion, lead is present in toxic concentrations in 35% of the teeth of the children studied. Urgent measures are needed to eliminate lead from gasoline, paint and other sources in the environment.

Use of filler limestone and construction and demolition residues for remediating soils contaminated with heavy metals: an assessment by means of plant uptake.

NASA Astrophysics Data System (ADS)

Banegas, Ascension; Martinez-Sanchez, Maria Jose; Agudo, Ines; Perez-Sirvent, Carmen

2010-05-01

A greenhouse trial was carried out to evaluate the assimilation of heavy metals by three types of horticultural plants (lettuce, broccoli and alfalfa), different parts of which are destined for human and animal consumption (leaves, roots, fruits). The plants were cultivated in four types of soil, one uncontaminated (T1), one soil collected in the surrounding area of Sierra Minera (T2), the third being remediated with residues coming from demolition and construction activities (T3) and the four remediated with filler limestone (T4). To determine the metal content, soil samples were first ground to a fine powder using an agate ball mill. Fresh vegetable samples were separated into root and aboveground biomass and then lyophilized. The DTPA-extractable content was also determined to calculate the bioavailable amount of metal. Finally, the translocation factor (TF) and bioconcentration factor (BCF) were calculated. Arsenic levels were obtained by using atomic fluorescence spectrometry with an automated continuous flow hydride generation (HG-AFS) spectrometer and Cd, Pb and Zn was determined by electrothermal atomization atomic absorption spectrometry (ETAAS) or flame atomic absorption spectrometry (FAAS). Samples of the leached water were also obtained and analyzed. According to our results, the retention of the studied elements varies with the type of plant and is strongly decreased by the incorporation of filler limestone and/or construction and demolition residues to the soils. This practice represents a suitable way to reduce the risk posed to the biota by the presence of high levels of heavy metal in soil.

Flow injection for the determination of Se(IV) and Se(VI) by hydride generation atomic absorption spectrometry with microwave oven on-line prereduction of Se(VI) to Se(IV)

NASA Astrophysics Data System (ADS)

Burguera, J. L.; Carrero, P.; Burguera, M.; Rondon, C.; Brunetto, M. R.; Gallignani, M.

1996-12-01

An on-line flow injection system has been developed for the selective determination of Se(IV) and Se(VI) in citric fruit juices and geothermal waters by hydride generation atomic absorption spectrometry with microwave-aided heating prereduction of Se(VI) to Se(IV). The samples and the prereductant solutions (4 mol l -1 HCl for Se(IV) and 12 mol l -1 HCl for Se(VI)) which circulated in a closed-flow circuit were injected by means of a time-based injector. This mixture was displaced by a carrier solution of 1% v/v of hydrochloric acid through a PTFE coil located inside the focused microwave oven and mixed downstream with a borohydride solution to generate the hydride. The linear ranges were 0-120 and 0-100 μg l -1 of Se(IV) and Se(VI), respectively. The detection limits were 1.0 μg l -1 for Se(IV) and 1.5 μg l -1 for Se(VI). The precision (about 2.0-2.5% RSD) and recoveries (96-98% for Se(IV) and 94-98% for Se(VI)) were good. Total selenium values were also obtained by electrothermal atomic absorption spectrometry which agreed with the content of both selenium species. The sample throughput was about 50 measurements per hour. The main advantage of the method is that the selective determination of Se(IV) and Se(VI) in citric fruit juices and geothermal waters is performed in a closed system with a minimum sample manipulation, exposure to the environment, minimum sample waste and operator attention.

Cu determination in crude oil distillation products by atomic absorption and inductively coupled plasma mass spectrometry after analyte transfer to aqueous solution

NASA Astrophysics Data System (ADS)

Kowalewska, Zofia; Ruszczyńska, Anna; Bulska, Ewa

2005-03-01

Cu was determined in a wide range of petroleum products from crude oil distillation using flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS) and inductively coupled plasma mass spectrometry (ICP-MS). Different procedures of sample preparation were evaluated: (i) mineralization with sulfuric acid in an open system, (ii) mineralization in a closed microwave system, (iii) combustion in hydrogen-oxygen flame in the Wickbold's apparatus, (iv) matrix evaporation followed by acid dissolution, and (v) acidic extraction. All the above procedures led to the transfer of the analyte into an aqueous solution for the analytical measurement step. It was found that application of FAAS was limited to the analysis of the heaviest petroleum products of high Cu content. In ICP-MS, the use of internal reference method (with Rh or In as internal reference element) was required to eliminate the matrix effects in the analysis of extracts and the concentrated solutions of mineralized heavy petroleum products. The detection limits (in original samples) were equal to, respectively, 10, 86, 3.3, 0.9 and 0.4 ng g - 1 in procedures i-v with ETAAS detection and 10, 78, 1.1 and 0.5 ng g - 1 in procedures i-iii and v with ICP-MS detection. The procedures recommended here were validated by recovery experiments, certified reference materials analysis and comparison of results, obtained for a given sample, in different ways. The Cu content in the analyzed samples was: 50-110 ng g - 1 in crude oil, < 0.4-6 ng g - 1 in gasoline, < 0.5-2 ng g - 1 in atmospheric oil, < 6-100 ng g - 1 in heavy vacuum oil and 140-300 ng g - 1 in distillation residue.

Flow injection determination of Se in dietary supplements using TiO2 mediated ultraviolet-photochemical volatile species generation

NASA Astrophysics Data System (ADS)

Nováková, E.; Linhart, O.; Červený, V.; Rychlovský, P.; Hraníček, J.

2017-08-01

This paper proposes a method for determination of selenium content in samples of dietary supplements using TiO2 mediated UV-photochemical vapor generation with quartz furnace atomic spectrometric detection. The flow-injection method was optimized for determination of selenium in the form of selenite or selenate ions. The limits of detection of the proposed method are 0.89 ng mL- 1 and 0.68 ng mL- 1 for selenite and selenate, respectively. Extraction in neutral medium was used for the leaching of selenate and NaOH solution was used for the leaching of selenite. The methods accuracy was verified against the declared amounts of Se in five different samples of over-the-counter dietary supplements and on NIST SRM 3280. The method was also compared to results achieved with determination by electrothermal atomization atomic absorption spectrometry following microwave decomposition. The recovery of selenium during sample preparation was tested by spiking the tablets prior to extraction and estimated to be approximately 100%. An interference study has been carried out to estimate the effect of concomitant elements on the methods accuracy.

Manganese and selenium concentrations in cerebrospinal fluid of seriously ill children.

PubMed

Franěk, Tomáš; Kotaška, Karel; Průša, Richard

2017-11-01

The homeostasis of essential trace elements such as selenium and manganese may be altered in patients with severe diseases of various etiologies (trauma brain injuries, tumors, leukemias, lymphomas, neurological diseases). Concentration of manganese and selenium were determined in cerebrospinal fluid by electrothermal atomic absorption spectrometry in 50 hospitalized children with various clinical ethiologies including oncological, neurological, and brain related diseases. The concentrations of manganese in cerebrospinal fluid of children were 0.97±0.67 μg/L. The concentrations of selenium were 13.3±3.5 μg/L. The concentrations were similar as published in adults. The values did not correlated with the age, gender and severity of the disease. We evaluated values of selenium and manganese in cerebrospinal fluid of seriously diseased children. © 2017 Wiley Periodicals, Inc.

Matrix elimination method for the determination of precious metals in ores using electrothermal atomic absorption spectrometry.

PubMed

Salih, Bekir; Celikbiçak, Omür; Döker, Serhat; Doğan, Mehmet

2007-03-28

Poly(N-(hydroxymethyl)methacrylamide)-1-allyl-2-thiourea) hydrogels, poly(NHMMA-ATU), were synthesized by gamma radiation using (60)Co gamma source in the ternary mixture of NHMMA-ATU-H(2)O. These hydrogels were used for the specific gold, silver, platinum and palladium recovery, pre-concentration and matrix elimination from the solutions containing trace amounts of precious metal ions. Elimination of inorganic matrices such as different transition and heavy metal ions, and anions was performed by adjusting the solution pH to 0.5 that was the selective adsorption pH of the precious metal ions. Desorption of the precious metal ions was performed by using 0.8 M thiourea in 3M HCl as the most efficient desorbing agent with recovery values more than 95%. In the desorption medium, thiourea effect on the atomic signal was eliminated by selecting proper pyrolysis and atomization temperatures for all precious metal ions. Precision and the accuracy of the results were improved in the graphite furnace-atomic absorption spectrometer (GFAAS) measurements by applying the developed matrix elimination method performing the adsorption at pH 0.5. Pre-concentration factors of the studied precious metal ions were found to be at least 1000-fold. Detection limits of the precious metal ions were found to be less than 10 ng L(-1) of the all studied precious metal ions by using the proposed pre-concentration method. Determination of trace levels of the precious metals in the sea-water, anode slime, geological samples and photographic fixer solutions were performed using GFAAS clearly after applying the adsorption-desorption cycle onto the poly(NHMMA-UTU) hydrogels.

Evaluation of zirconium as a permanent chemical modifier using synchrotron radiation and imaging techniques for lithium determination in sediment slurry samples by ET AAS.

PubMed

Flores, Araceli V; Pérez, Carlos A; Arruda, Marco A Z

2004-02-27

In the present paper, lithium was determined in river sediment using slurry sampling and electrothermal atomic absorption spectrometry (ET AAS) after L'vov platform coating with zirconium (as a permanent chemical modifier). The performance of this modifier and its distribution on the L'vov platform after different heating cycles were evaluated using synchrotron radiation X-ray fluorescence (SRXRF) and imaging scanning electron microscopy (SEM) techniques. The analytical conditions for lithium determination in river sediment slurries were also investigated and the best conditions were obtained employing 1300 and 2300 degrees C for pyrolysis and atomization temperatures, respectively. In addition, 100mg of sediment samples were prepared using 4.0moll(-1) HNO(3). The Zr-coating permitted lithium determination with good precision and accuracy after 480 heating cycles using the same platform for slurry samples. The sediment samples were collected from five different points of the Cachoeira river, São Paulo, Brazil. The detection and quantification limits were, respectively, 0.07 and 0.23mugl(-1).

Strategy for determination of LOD and LOQ values--some basic aspects.

PubMed

Uhrovčík, Jozef

2014-02-01

The paper is devoted to the evaluation of limit of detection (LOD) and limit of quantification (LOQ) values in concentration domain by using 4 different approaches; namely 3σ and 10σ approaches, ULA2 approach, PBA approach and MDL approach. Brief theoretical analyses of all above mentioned approaches are given together with directions for their practical use. Calculations and correct calibration design are exemplified by using of electrothermal atomic absorption spectrometry for determination of lead in drinking water sample. These validation parameters reached 1.6 μg L(-1) (LOD) and 5.4 μg L(-1) (LOQ) by using 3σ and 10σ approaches. For obtaining relevant values of analyte concentration the influence of calibration design and measurement methodology were examined. The most preferred technique has proven to be a method of preconcentration of the analyte on the surface of the graphite cuvette (boost cycle). © 2013 Elsevier B.V. All rights reserved.

An analytical procedure for the determination of aluminum used in antiperspirants on human skin in Franz™ diffusion cell.

PubMed

Guillard, Olivier; Fauconneau, Bernard; Favreau, Frédéric; Marrauld, Annie; Pineau, Alain

2012-04-01

A local case report of hyperaluminemia (aluminum concentration: 3.88 µmol/L) in a woman using an aluminum-containing antiperspirant for 4 years raises the question of possible transdermal uptake of aluminum salt as a future public health problem. Prior to studying the transdermal uptake of three commercialized cosmetic formulas, an analytical assay of aluminum (Al) in chlorohydrate form (ACH) by Zeeman Electrothermal Atomic Absorption Spectrophotometer (ZEAAS) in a clean room was optimized and validated. This analysis was performed with different media on human skin using a Franz(™) diffusion cell. The detection and quantification limits were set at ≤ 3 µg/L. Precision analysis as within-run (n = 12) and between-run (n = 15-68 days) yield CV ≤ 6%. The high analytic sensitivity (2-3 µg/L) and low variability should allow an in vitro study of the transdermal uptake of ACH.

Determination of trace amounts of cobalt in blood

DOE Office of Scientific and Technical Information (OSTI.GOV)

Godlewska, B.; Hulanicki, A.; Abou-Shakra, F.R.

1994-11-01

The analysis of cobalt in whole blood and blood fractions has been carried out using three different analytical techniques namely, electrothermal atomic absorption spectrometry, inductively coupled plasma mass spectrometry and cathodic stripping voltammetry. This study showed that inductively coupled plasma mass spectrometry was the better equipped technique for conducting such analyses due to its low detection limits and wide linear dynamic range. The results ranged between 0.7 - 2.62 {mu}g/l for plasma, 1.02 - 2.31 {mu}g/l for serum, and 0.66 - 1.28 {mu}g/l for whole blood. The introduction of different forms of cobalt to Wistar rats resulted in a differingmore » distribution of the element between serum and whole blood. This observation suggests that there are at least two modes of Co uptake and transport depending on the administered or taken chemical form.« less

Chromium in Postmortem Material.

PubMed

Dudek-Adamska, Danuta; Lech, Teresa; Konopka, Tomasz; Kościelniak, Paweł

2018-04-17

Recently, considerable attention has been paid to the negative effects caused by the presence and constant increase in concentration of heavy metals in the environment, as well as to the determination of their content in human biological samples. In this paper, the concentration of chromium in samples of blood and internal organs collected at autopsy from 21 female and 39 male non-occupationally exposed subjects is presented. Elemental analysis was carried out by an electrothermal atomic absorption spectrometer after microwave-assisted acid digestion. Reference ranges of chromium in the blood, brain, stomach, liver, kidneys, lungs, and heart (wet weight) in the population of Southern Poland were found to be 0.11-16.4 ng/mL, 4.7-136 ng/g, 6.1-76.4 ng/g, 11-506 ng/g, 2.9-298 ng/g, 13-798 ng/g, and 3.6-320 ng/g, respectively.

Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods.

PubMed

Grotti, Marco; Abelmoschi, Maria Luisa; Soggia, Francesco; Frache, Roberto

2003-01-01

A study was carried out on the preconcentration of ultratrace amounts of cadmium, lead, manganese, copper and iron from high-salinity aqueous samples and determination by atomic spectrometry methods. Sample volume, amount of resin, loading flow rate, and elution volume were optimized in order to obtain the simultaneous preconcentration of all the analytes. Quantitative recoveries were obtained by using 200 mg of iminodiacetic resin with a loading flow rate of 2 mL min(-1), elution volume of 3 mL and sample volume of 50-450 mL. Only copper in seawater samples was not completely retained by the resin (60-70% recovery), due to unfavorable competition of iminodiacetic-active groups with organically bound metal.To quantify the metals in the eluates, two atomic spectrometry techniques were compared: electrothermal atomization atomic absorption spectrometry (ETAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) with simultaneous CCD detection system. Both techniques are suitable for sample analysis with detection limits of 1.0, 4.7, 3.3, 6.8, and 53 ng L(-1) using ETAAS and 12, 122, 3.4, 17, and 21 ng L(-1) using ICP-OES for Cd, Pb, Mn, Cu, and Fe, respectively. Relative standard deviations of the procedures ranged from 1.7 to 14% at the sub-microg L(-1) concentration level. The accuracy of both methods was verified by analyzing various certified reference materials (river water, estuarine water, coastal and off-shore seawater).

Determination of boron in blood, urine and bone by electrothermal atomic absorption spectrometry using zirconium and citric acid as modifiers

NASA Astrophysics Data System (ADS)

Burguera, Marcela; Burguera, José Luis; Rondón, Carlos; Carrero, Pablo

2001-10-01

A comparative study of various potential chemical modifiers (Au, Ba, Be, Ca, Cr, Ir, La, Lu, Mg, Ni, Pd, Pt, Rh, Ru, Sr, V, W, and Zr), and different 'coating' treatments (Zr, W, and W+Rh) of the pyrolytic graphite platform of a longitudinally heated graphite tube atomizer for thermal stabilization and determination of boron was undertaken. The use of Au, Ba, Be, Cr, Ir, Pt, Rh, Ru, Sr and V as modifiers, and of W+Rh coating produced erratic, and noisy signals, while the addition of La, Ni and Pd as modifiers, and the W coating had positive effects, but with too high background absorption signals, rendering their use unsuitable for boron determination even in aqueous solutions. The atomic absorption signal for boron was increased and stabilized when the platform was coated with Zr, and by the addition of Ca, Mg, Lu, W or Zr as modifiers. Only the addition of 10 μg of Zr as a modifier onto Zr-treated platforms allowed the use of a higher pyrolysis temperature without analyte losses. The memory effect was minimized by incorporating a cleaning step with 10 μl of 50 g l -1 NH 4F HF after every three boron measurements. The addition of 10 μl of 15 g l -1 citric acid together with Zr onto Zr-treated platforms significantly improved the characteristic mass to m0=282 pg, which is adequate for biological samples such as urine and bone, although the sensitivity was still inadequate for the determination of boron in blood of subjects without supplementary diet. Under optimized conditions, the detection limit (3σ) was 60 μg l -1. The amount of boron found in whole blood, urine and femur head samples from patients with osteoporosis was in agreement with values previously reported in the literature.

Selenium speciation using capillary electrophoresis coupled with modified electrothermal atomic absorption spectrometry after selective extraction with 5-sulfosalicylic acid functionalized magnetic nanoparticles.

PubMed

Yan, Lizhen; Deng, Biyang; Shen, Caiying; Long, Chanjuan; Deng, Qiufen; Tao, Chunyao

2015-05-22

A new method for selenium speciation in fermented bean curd wastewater and juice was described. This method involved sample extraction with 5-sulfosalicylic acid (SSA)-functionalized silica-coated magnetic nanoparticles (SMNPs), capillary electrophoresis (CE) separation, and online detection with a modified electrothermal atomic absorption spectrometry (ETAAS) system. The modified interface for ETAAS allowed for the introduction of CE effluent directly through the end of the graphite tube. Elimination of the upper injection hole of the graphite tube reduced the loss of the anlayte and enhanced the detection sensitivity. The SSA-SMNPs were synthesized and used to extract trace amounts of selenite [Se(IV)], selenite [Se(VI)], selenomethionine (SeMet), and selenocystine (SeCys2) from dilute samples. The concentration enrichment factors for Se(VI), Se(IV), SeMet, and SeCys2 were 21, 29, 18, and 12, respectively, using the SSA-SMNPs extraction. The limits of detection for Se(VI), Se(IV), SeMet, and SeCys2 were 0.18, 0.17, 0.54, 0.49ngmL(-1), respectively. The RSD values (n=6) of method for intraday were observed between 0.7% and 2.9%. The RSD values of method for interday were less than 3.5%. The linear range of Se(VI) and Se(IV) were in the range of 0.5-200ngmL(-1), and the linear ranges of SeMet and SeCys2 were 2-500 and 2-1000ngmL(-1), respectively. The detection limits of this method were improved by 10 times due to the enrichment by the SSA-SMNP extraction. The contents of Se(VI) and Se(IV) in fermented bean curd wastewater were measured as 3.83 and 2.62ngmL(-1), respectively. The contents of Se(VI), Se(IV), SeMet, and SeCys2 in fermented bean curd juice were determined as 6.39, 4.08, 2.77, and 4.00ngmL(-1), respectively. The recoveries were in the range of 99.14-104.5% and the RSDs (n=6) of recoveries between 0.82% and 3.5%. Copyright © 2015 Elsevier B.V. All rights reserved.

Trace metal assay of U(3)O(8) powder by electrothermal AAS.

PubMed

Page, A G; Godbole, S V; Kulkarni, M J; Porwal, N K; Shelar, S S; Joshi, B D

1983-10-01

Methods have been developed for the direct determination of Ag, Ca, K., Li, Mg, Na, Pb, Sn and Zn in U(3)O(8) powder samples by electrothermal AAS. Nanogram and lower amounts of these elements have been determined with a relative standard deviation of 6-16% in mg amounts of sample (either alone or mixed with an equal weight of graphite). The results for NBL reference samples were in reasonable agreement with the certified values. X-Ray diffraction studies on the residues left from the graphite mixtures after the atomization cycle, confirmed the formation of uranium carbide (UC(2)).

Tellurium speciation analysis using hydride generation in situ trapping electrothermal atomic absorption spectrometry and ruthenium or palladium modified graphite tubes.

PubMed

Yildirim, Emrah; Akay, Pınar; Arslan, Yasin; Bakirdere, Sezgin; Ataman, O Yavuz

2012-12-15

Speciation of tellurium can be achieved by making use of different kinetic behaviors of Te(IV) and Te(VI) upon their reaction with sodium borohydride using hydride generation. While Te(IV) can form H(2)Te, Te(VI) will not form any volatile species during the course of hydride formation and measurement by atomic absorption spectrometry. Quantitative reduction of Te(VI) was achieved through application of a microwave assisted prereduction of Te(VI) in 6.0 mol/L HCl solution. Enhanced sensitivity was achieved by in situ trapping of the generated H(2)Te species in a previously heated graphite furnace whose surface was modified using Pd or Ru. Overall efficiency for in situ trapping in pyrolytically coated graphite tube surface was found to be 15% when volatile analyte species are trapped for 60s at 300°C. LOD and LOQ values were calculated as 0.086 ng/mL and 0.29 ng/mL, respectively. Efficiency was increased to 46% and 36% when Pd and Ru surface modifiers were used, respectively. With Ru modified graphite tube 173-fold enhancement was obtained over 180 s trapping period with respect to ETAAS; the tubes could be used for 250 cycles. LOD values were 0.0064 and 0.0022 ng/mL for Pd and Ru treated ETAAS systems, respectively, for 180 s collection of 9.6 mL sample solution. Copyright © 2012 Elsevier B.V. All rights reserved.

[Study on the determination of trace gallium in molybdenum-coated pyrolytic graphite tube by electrothermal absorption spectrometry].

PubMed

Huang, Yu-an; Zhou, Fang-qin; Long, Si-hua; Yang, Liu

2004-02-01

The effects on gallium atomization in the pyrolytic graphite tube imposed by different matrix modifiers and different coatings were discussed detailedly in this paper. In the presence of matrix modifier of Ni(NO3)2 the matrix interference was eliminated efficiently. The pyrolytic graphite tubes were coated differently with lanthanum, zirconium, and molybdenum to avoid producing gallium carbide. Results showed that the tube with molybdenum coating was the best. On this basis, the mechanism of gallium atomization in the molybdenum-coated pyrolytic graphite tube using Ni(NO3)2 as a matrix modifier was studied furthermore; in addition, the parameters of the operation were optimized. As a result, a new method improved in many aspects was developed to detect trace gallium in complicated sample of gangue. The outcomes of practical applications indicated that the method could satisfy the requests of analysis and that the manipulations were simple to achieve. The characteristic content, the detection limit, and the adding recoveries were 2.12 x 10(-11) g, 1.4 x 10(-10) g and 97.4%-102.7% respectively, and the relative standard deviation was less than or equal to 3.6% (n = 11).

Tree ring wood analysis after hydrogen peroxide pressure decomposition with inductively coupled plasma atomic emission spectrometry and electrothermal vaporization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matusiewicz, H.; Barnes, R.M.

1985-02-01

A method utilizing pressure decomposition to minimize sample pretreatment is described for the inductively coupled plasma atomic emission spectrometric analysis of red spruce and sugar maple. Cores collected from trees growing on Camels Hump Mountain, Vermont, were divided into decade increments in order to monitor the temporal changes in concentrations of 21 elements. Dried wood samples were decomposed in a bomb made of Teflon with 50% hydrogen peroxide heated in an oven at 125/sup 0/C for 4 h. The digestion permitted use of aqueous standards and minimized any potential matrix effects. The element concentrations were obtained sequentially by electrothermal vaporizationmore » ICP-AES using 5 ..mu..L sample aliquots. The method precision varied between 3 and 12%. Elements forming oxyanions (Al, As, Fe, Ge, Mn, Si, V) were found at elevated concentrations during the most recent three decades, while other metal (e.g., Mg, Zn) concentrations were unchanged or decreased. 45 references, 6 tables, 1 figure.« less

Geochemical background of zinc, cadmium and mercury in anthropically influenced soils in a semi-arid zone (SE, Spain)

NASA Astrophysics Data System (ADS)

García-Lorenzo, M. L.; Pérez-Sirvent, C.; Martínez-Sánchez, M. J.; Molina, J.; Tudela, M. L.; Hernández-Córdoba, M.

2009-04-01

This work seeks to establish the geochemical background for three potentially toxic trace elements (Zn, Cd and Hg) in a pilot zone included in the DesertNet project in the province of Murcia. The studied area, known as Campo de Cartagena, Murcia (SE Spain) is an area of intensive agriculture and has been much affected over the years by anthropic activity. The zone can be considered an experimental pilot zone for establishing background levels in agricultural soils. Sixty four samples were collected and corresponded to areas subjected to high and similar agricultural activity or soils with natural vegetation, which correspond to abandoned agricultural areas. The Zn content was determined by flame atomic absorption spectrometry. The Cd content was determined by electrothermal atomization atomic absorption spectrometry and mercury content was determined by atomic fluorescence spectrometry. Geostatistical analysis consisting of kriging and mapping was performed using the geostatistical analyst extension of ArcGIS 8.3. Zinc values ranged from 10 mg kg-1 to 151 mg kg-1, with an average value of 45 mg kg-1. Cadmium values ranged between 0.1 mg kg-1 and 0.9mg kg-1, with a mean value of 0.3 mg kg-1 and mercury values ranged from 0.1 mg kg-1 to 2.3 mg kg-1, with a mean value of 0.5 mg kg-1. At a national level, the Spanish Royal Decree 9/2005 proposes toxicological and statistical approaches to establish background values. According to the statistical approach, background values consist of the median value for the selected element. The background values for Zn, Cd and Hg in the studied area were 40 mg kg-1 for Zn, 0.3 mg kg-1 for Cd and 0.4 mg kg-1 for Hg.

Monte Carlo simulation of electrothermal atomization on a desktop personal computer

NASA Astrophysics Data System (ADS)

Histen, Timothy E.; Güell, Oscar A.; Chavez, Iris A.; Holcombea, James A.

1996-07-01

Monte Carlo simulations have been applied to electrothermal atomization (ETA) using a tubular atomizer (e.g. graphite furnace) because of the complexity in the geometry, heating, molecular interactions, etc. The intense computational time needed to accurately model ETA often limited its effective implementation to the use of supercomputers. However, with the advent of more powerful desktop processors, this is no longer the case. A C-based program has been developed and can be used under Windows TM or DOS. With this program, basic parameters such as furnace dimensions, sample placement, furnace heating and kinetic parameters such as activation energies for desorption and adsorption can be varied to show the absorbance profile dependence on these parameters. Even data such as time-dependent spatial distribution of analyte inside the furnace can be collected. The DOS version also permits input of external temperaturetime data to permit comparison of simulated profiles with experimentally obtained absorbance data. The run-time versions are provided along with the source code. This article is an electronic publication in Spectrochimica Acta Electronica (SAE), the electronic section of Spectrochimica Acta Part B (SAB). The hardcopy text is accompanied by a diskette with a program (PC format), data files and text files.

Trends in tungsten coil atomic spectrometry

NASA Astrophysics Data System (ADS)

Donati, George L.

Renewed interest in electrothermal atomic spectrometric methods based on tungsten coil atomizers is a consequence of a world wide increasing demand for fast, inexpensive, sensitive, and portable analytical methods for trace analysis. In this work, tungsten coil atomic absorption spectrometry (WCAAS) and tungsten coil atomic emission spectrometry (WCAES) are used to determine several different metals and even a non-metal at low levels in different samples. Improvements in instrumentation and new strategies to reduce matrix effects and background signals are presented. Investigation of the main factors affecting both WCAAS and WCAES analytical signals points to the importance of a reducing, high temperature gas phase in the processes leading to atomic cloud generation. Some more refractory elements such as V and Ti were determined for the first time by double tungsten coil atomic emission spectrometry (DWCAES). The higher temperatures provided by two atomizers in DWCAES also allowed the detection of Ag, Cu and Sn emission signals for the first time. Simultaneous determination of several elements by WCAES in relatively complex sample matrices was possible after a simple acid extraction. The results show the potential of this method as an alternative to more traditional, expensive methods for fast, more effective analyses and applications in the field. The development of a new metallic atomization cell is also presented. Lower limits of detection in both WCAAS and WCAES determinations were obtained due to factors such as better control of background signal, smaller, more isothermal system, with atomic cloud concentration at the optical path for a longer period of time. Tungsten coil-based methods are especially well suited to applications requiring low sample volume, low cost, sensitivity and portability. Both WCAAS and WCAES have great commercial potential in fields as diverse as archeology and industrial quality control. They are simple, inexpensive, effective methods for trace metal determinations in several different samples, representing an important asset in today's analytical chemistry.

Investigation of fluorine content in PM2.5 airborne particles of Istanbul, Turkey.

PubMed

Ozbek, Nil; Baltaci, Hakki; Baysal, Asli

2016-07-01

Fluorine determination in airborne samples is important due to its spread into the air from both natural and artificial sources. It can travel by wind over large distances before depositing on the Earth's surface. Its concentration in various matrices are limited and controlled by the regulations for causing health risks associated with environmental exposures. In this work, fluorine was determined in PM2.5 airborne samples by high-resolution continuum source electrothermal atomic absorption spectrometry. For these purpose, the PM2.5 airborne particulates were collected on quartz filters using high-volume samplers (500 L/min) in Istanbul (Turkey) for 96 h during January to June in 2 years. Then, instrumental and experimental parameters were optimized for the analyte in airborne samples. The validity of the method for the analyte was tested using standard reference material, and certified values were found in the limits of 95 % confidence level. The fluorine concentrations and meteorological conditions were compared statistically.

Development, validation and accreditation of a method for the determination of Pb, Cd, Cu and As in seafood and fish feed samples.

PubMed

Psoma, A K; Pasias, I N; Rousis, N I; Barkonikos, K A; Thomaidis, N S

2014-05-15

A rapid, sensitive, accurate and precise method for the determination of Pb, Cd, As and Cu in seafood and fish feed samples by Simultaneous Electrothermal Atomic Absorption Spectrometry was developed in regard to Council Directive 333/2007EC and ISO/IEC 17025 (2005). Different approaches were investigated in order to shorten the analysis time, always taking into account the sensitivity. For method validation, precision (repeatability and reproducibility) and accuracy by addition recovery tests have been assessed as performance criteria. The expanded uncertainties based on the Eurachem/Citac Guidelines were calculated. The method was accredited by the Hellenic Accreditation System and it was applied for an 8 years study in seafood (n=202) and fish feeds (n=275) from the Greek market. The annual and seasonal variation of the elemental content and correlation among the elemental content in fish feeds and the respective fish samples were also accomplished. Copyright © 2013 Elsevier Ltd. All rights reserved.

Solidified Floating Organic Drop Microextraction for the Detection of Trace Amount of Lead in Various Samples by Electrothermal Atomic Absorption Spectrometry.

PubMed

Aydın Urucu, Oya; Dönmez, Şeyda; Kök Yetimoğlu, Ece

2017-01-01

A novel method was developed for determination of trace amounts of lead in water and food samples. Solidified floating organic drop microextraction was used to preconcentrate the lead ion. After the analyte was complexed with 1-(2-pyridylazo)-2-naphthol, undecanol and acetonitrile were added as extraction and dispersive solvent, respectively. Variables such as pH, volumes of extraction and dispersive solvents, and concentration of chelating agent were optimized. Under the optimum conditions, the detection limit of Pb (II) was determined as 0.042  µ g L -1 with an enrichment factor of 300. The relative standard deviation is <10%. Accuracy of the developed procedure was evaluated by the analysis of certified reference material of human hair (NCS DC 73347) and wastewater (SPS-WW2) with satisfactory results. The developed procedure was then successfully applied to biscuit and water samples for detection of Pb (II) ions.

Occupational and environmental lead exposure to adolescent workers in battery recycling workshops.

PubMed

Kazi, Tasneem Gul; Shah, Faheem; Afridi, Hassan Imran; Naeemullah

2015-12-01

Lead (Pb), as other environmental neurotoxicant substances, has the capability to interfere with many biochemical events present in cells throughout the body. In the present study, the environmental and occupational exposure to Pb has been assessed by analyzing the scalp hair samples of male adolescents aged 12-15 years, who have worked for the last 12-36 months in Pb battery recycling workshops (BRWs). For comparative purposes, gender and age-matched subjects living in the vicinity of recycling workshops as well as in areas without industrial activity were used as controls. The scalp hair samples were oxidized by acid in a microwave oven prior to determination of Pb by electrothermal atomic absorption spectrometry. The results indicated that both workers and nonworking exposed subjects had higher levels of Pb than nonexposed controls. The contents of Pb in scalp hair of adolescent workers in the present study were compared with those reported in other studies. © The Author(s) 2013.

Assessment of trace metals pollution in estuarine sediments using SEM-AVS and ERM-ERL predictions.

PubMed

Garcia, Carlos Alexandre Borges; Passos, Elisangela de Andrade; Alves, José do Patrocínio Hora

2011-10-01

This paper presents the distributions of the investigation of trace metals geochemistry in surface sediments of the Sergipe river estuary, northeast Brazil. Analyses were carried out by Flame or electrothermal atomic absorption spectrometry (FAAS or ETAAS). Principal component analysis was applied to results to identify any groupings among the different sampling sites. In order to determine the extent of contamination, taking into account natural variability within the region, metal concentrations were normalized relative to aluminium. Cr, Cu, Ni and Zn contamination was observed in sediments from the area receiving highest inputs of domestic wastes, while cadmium contamination occurred in sediments from the region affected by highest inflows of industrial effluents. Possible toxicity related to these metals was examined using the relationship simultaneously extracted metals/acid volatile sulfide and by comparing sediment chemical data with sediment quality guidelines ERL-ERM values. Results obtained using the two methods were in agreement and indicated that adverse effects on aquatic biota should rarely occur.

In vitro percutaneous penetration and characterization of silver from silver-containing textiles

PubMed Central

Bianco, Carlotta; Kezic, Sanja; Crosera, Matteo; Svetličić, Vesna; Šegota, Suzana; Maina, Giovanni; Romano, Canzio; Larese, Francesca; Adami, Gianpiero

2015-01-01

The objective of this study was to determine the in vitro percutaneous penetration of silver and characterize the silver species released from textiles in different layers of full thickness human skin. For this purpose, two different wound dressings and a garment soaked in artificial sweat were placed in the donor compartments of Franz cells for 24 hours. The concentration of silver in the donor phase and in the skin was determined by an electrothermal atomic absorption spectrometer (ET-AAS) and by inductively coupled plasma mass spectrometer (ICP-MS). The characterization of silver species in the textiles and in the skin layers was made by scanning electron microscopy with integrated energy dispersive X-ray spectroscopy (SEM-EDX). Additionally, the size distribution of silver nanoparticles in the textiles was performed by atomic force microscopy (AFM). On the surface of all investigated materials, silver nanoparticles of different size and morphology were found. Released silver concentrations in the soaking solutions (ie, exposure concentration) ranged from 0.7 to 4.7 μg/mL (0.6–4.0 μg/cm2), fitting the bactericidal range. Silver and silver chloride aggregates at sizes of up to 1 μm were identified both in the epidermis and dermis. The large size of these particles suggests that the aggregation occurred in the skin. The formation of these aggregates likely slowed down the systemic absorption of silver. Conversely, these aggregates may form a reservoir enabling prolonged release of silver ions, which might lead to local effects. PMID:25792824

Determination of trace elements in dolomite and gypsum by atomic absorption spectrometry: overcoming the matrix interference by flotation separation

NASA Astrophysics Data System (ADS)

Stafilov, Trajče; Zendelovska, Dragica; Pavlovska, Gorica; Čundeva, Katarina

2002-05-01

The interferences of Ca and Mg as matrix elements in dolomite and gypsum on Ag, Cd, Cr, Mn, Tl and Zn absorbances during their electrothermal atomic absorption spectrometric (ETAAS) determination are investigated. The results reveal that Ca and Mg do not interfere on Zn and Mn, tend to decrease absorbances of Ag, Cd and Cr, while Tl suffers the most significant influence. A flotation separation method is proposed to eliminate matrix interferences. Hydrated iron(III) oxide, Fe 2O 3· xH 2O, and iron(III) hexamethylenedithiocarbamate, Fe(HMDTC) 3, are applied as flotation collectors. The influence of hydrophobic dithiocarbamate anion, HMDTC, on flotation recoveries of each analyte is studied. The most suitable concentrations of dolomite and gypsum solutions for flotation are determined. To avoid flotation suppression due to the reaction of Ca 2+ and Mg 2+ with surfactant ions, a fit foaming agent was selected. The elements present in dolomite and gypsum as traces have been analyzed by ETAAS. Their ETAAS limits of detection following flotation are found to be 0.021 μg·g -1 for Ag, 0.019 μg·g -1 for Cd, 0.014 μg·g -1 for Cr and 0.11 μg·g -1 for Tl. The determination of Mn and Zn can be performed by flame AAS (FAAS). The limit of detection for Mn is 1.5 μg·g -1, while for Zn 0.8 μg·g -1.

Heavy metals and its chemical speciation in sewage sludge at different stages of processing.

PubMed

Tytła, Malwina; Widziewicz, Kamila; Zielewicz, Ewa

2016-01-01

The analysis of heavy metal concentrations and forms in sewage sludge constitutes an important issue in terms of both health and environmental hazards the metals pose. The total heavy metals concentration enables only the assessment of its contamination. Hence the knowledge of chemical forms is required to determine their environmental mobility and sludge final disposal. Heavy metals speciation was studied by using four-stage sequential extraction BCR (Community Bureau of Reference). This study was aimed at determining the total concentration of selected heavy metals (Zn, Cu, Ni, Pb, Cd, Cr and Hg) and their chemical forms (except for Hg) in sludge collected at different stages of its processing at two municipal Wastewater Treatment Plants in southern Poland. Metals contents in sludge samples were determined by using flame atomic absorption spectrometry (FAAS) and electrothermal atomic absorption spectrometry (ETAAS). This study shows that Zn and Cu appeared to be the most abundant in sludge, while Cd and Hg were in the lowest concentrations. The sewage sludge revealed the domination of immobile fractions over the mobile ones. The oxidizable and residual forms were dominant for all the heavy metals. There was also a significant difference in metals speciation between sludges of different origin which was probably due to differences in wastewater composition and processes occurring in biological stage of wastewater treatment. The results indicate a negligible capability of metals to migrate from sludge into the environment. Our research revealed a significant impact of thickening, stabilization and hygienization on the distribution of heavy metals in sludge and their mobility.

The use of emulsions for the determination of methylmercury and inorganic mercury in fish-eggs oil by cold vapor generation in a flow injection system with atomic absorption spectrometric detection.

PubMed

Burguera, J L; Quintana, I A; Salager, J L; Burguera, M; Rondón, C; Carrero, P; Anton de Salager, R; Petit de Peña, Y

1999-04-01

An on-line time based injection system used in conjunction with cold vapor generation atomic absorption spectrometry and microwave-aided oxidation with potassium persulfate has been developed for the determination of the different mercury species in fish-eggs oil samples. A three-phase surfactant-oil-water emulsion produced an advantageous flow when a peristaltic pump was used to introduce the highly viscous sample into the system. The optimum proportion of the oil-water mixture ratio was 2:3 v/v with a Tween 20 surfactant concentration in the emulsion of 0.008% v/v. Inorganic mercury was determined after reduction with sodium borohydride while total mercury was determined after an oxidation step with persulfate prior to the reduction step to elemental mercury with the same reducing agent. The difference between total and inorganic mercury determined the organomercury content in samples. A linear calibration graph was obtained in the range 0.1-20 micrograms l-1 of Hg2+ by injecting 0.7 ml of samples. The detection limits based on 3 sigma of the blank signals were 0.11 and 0.12 microgram l-1 for total and inorganic mercury, respectively. The relative standard deviation of ten independent measurements were 2.8 and 2.2% for 10 micrograms l-1 and 8.8 and 9.0% for 0.1 microgram l-1 amounts of total and inorganic mercury, respectively. The recoveries of 0.3, 0.6 and 8 micrograms l-1 of inorganic and organic mercury added to fish-eggs oil samples ranged from 93.0 to 94.8% and from 100 to 106%, respectively. Good agreement with those values obtained for total mercury content in real samples by electrothermal atomic absorption spectrometry was also obtained, differences between mean values were < 7%. With the proposed procedure, 22 proteropterous catfish-eggs oil samples from the northwestern coast of Venezuela were measured; while the organic mercury lay in the range 2.0 and 3.3 micrograms l-1, inorganic mercury was not detected.

Feasibility of high-resolution continuum source molecular absorption spectrometry in flame and furnace for sulphur determination in petroleum products

NASA Astrophysics Data System (ADS)

Kowalewska, Zofia

2011-07-01

For the first time, high-resolution molecular absorption spectrometry with a high-intensity xenon lamp as radiation source has been applied for the determination of sulphur in crude oil and petroleum products. The samples were analysed as xylene solutions using vaporisation in acetylene-air flame or in an electrothermally heated graphite furnace. The sensitive rotational lines of the CS molecule, belonging to the ∆ν = 0 vibrational sequence within the electronic transition X 1∑ + → A 1П, were applied. For graphite furnace molecular absorption spectrometry, the Pd + Mg organic modifier was selected. Strong interactions with Pd atoms enable easier decomposition of sulphur-containing compounds, likely through the temporal formation of Pd xS y molecules. At the 258.056 nm line, with the wavelength range covering central pixel ± 5 pixels and with application of interactive background correction, the detection limit was 14 ng in graphite furnace molecular absorption spectrometry and 18 mg kg -1 in flame molecular absorption spectrometry. Meanwhile, application of 2-points background correction found a characteristic mass of 12 ng in graphite furnace molecular absorption spectrometry and a characteristic concentration of 104 mg kg -1 in flame molecular absorption spectrometry. The range of application of the proposed methods turned out to be significantly limited by the properties of the sulphur compounds of interest. In the case of volatile sulphur compounds, which can be present in light petroleum products, severe difficulties were encountered. On the contrary, heavy oils and residues from distillation as well as crude oil could be analysed using both flame and graphite furnace vaporisation. The good accuracy of the proposed methods for these samples was confirmed by their mutual consistency and the results from analysis of reference samples (certified reference materials and home reference materials with sulphur content determined by X-ray fluorescence spectrometry).

Slurry sampling electrothermal vaporization inductively coupled plasma mass spectrometry for steelmaking flue dust analysis

NASA Astrophysics Data System (ADS)

Coedo, A. G.; Dorado, T.; Padilla, I.; Maibusch, R.; Kuss, H.-M.

2000-02-01

A commercial atomic absorption graphite furnace (AAGF), with a self-made adapter and valve system, was used as a slurry sampling cell for electrothermal vaporization inductively coupled plasma mass spectrometry (ETV-ICP-MS). The system was applied to the determination of As, Sn, Sb, Se, Te, Bi, Cd, V, Ti and Mo in steelmaking flue dusts. Experimental conditions with respect to ETV and ICP-MS operating parameters were optimized. Compared to aqueous solutions, slurry samples were found to present better analyte transport. Microgram amounts of Rh were used to reduce the difference in analyte response in sensitivity for aqueous solutions of the tested analytes. No such increasing effect was observed for slurry samples and aqueous standards. An added quantity of Rh acting as modifier/carrier resulted in an increase for the same analytes in matrix-slurry solutions, even the addition of an extra Rh quantity has resulted in a decrease in the signals. The effect of Triton X-100 (used as a dispersant agent) on analyte intensity and precision was also studied. External calibration from aqueous standards spiked with 100 μg ml -1 Rh was performed to quantified 0.010 g/100 ml slurry samples. Results are presented for a certified reference electrical arc furnace flue dust (EAF): CRM-876-1 (Bureau of Analysis Samples Ltd., Cleveland, UK), a reference sample of coke ashes X-3705 (from AG der Dillinger Hüttenwerke, Germany), and a representative sample of EAF flue dust from a Spanish steelmaking company (CENIM-1). For the two reference materials an acceptable agreement with certificate values was achieved, and the results for the CENIM sample matched with those obtained from conventional nebulization solution.

Relationship between serum selenium, sociodemographic variables, other trace elements and lipid profile in an adult Spanish population.

PubMed

González-Estecha, Montserrat; Palazón-Bru, Irene; Bodas-Pinedo, Andrés; Trasobares, Elena; Palazón-Bru, Antonio; Fuentes, Manuel; Cuadrado-Cenzual, M Ángeles; Calvo-Manuel, Elpidio

2017-09-01

Several studies have shown an inverse relationship between selenium status and cardiovascular health, although epidemiologic evidence yielded by the randomized trials did not find a beneficial effect of selenium administration. The aim of this study was to analyze the association between serum selenium levels and lipid profile adjusted by age, sex and other associated factors among a general adult population in Spain. We recruited 372 hospital employee volunteers (60 men and 312 women) with a mean age of 47 (SD: 10.9), whom were given a standardized questionnaire. Serum selenium concentration was measured by electrothermal atomization atomic absorption spectrometry. Serum copper and zinc concentrations were measured using flame atomic absorption spectrometry. The mean of serum selenium was 79.5μg/L (SD: 11.7) with no sex-dependent differences. In the multivariate linear regression analysis, the associated factors with the mean levels of selenium were: age (β=0.223; CI 95%: 0.101-0.345), p<0.001; widowhood (β=-9.668; CI 95%: -17.234 to -2.102), p=0.012; calcium supplements (β=3.949; CI 95%: 0.059-7.838), p=0.047; zinc (β=0.126; CI 95%: 0.013-0.238), p=0.028 and glucose (β=0.172; CI 95%: 0.062- 0.281), p=0.002; Participants with serum selenium≥79.5μg/L were 1.98 (OR=1.98; CI 95% 1.17-3.35; p=0.011) and 2.04 times (OR=2.04; CI 95% 1.06-3.97; p=0.034) more likely to have cholesterol ≥200mg/dL and LDL-c ≥100mg/dL respectively than those with serum selenium <79.5μg/L. Higher selenium was positively associated with increased total and LDL cholesterol but not with HDL-c and triglycerides. More studies are needed in order to confirm the lower serum selenium findings in widows. Copyright © 2016 Elsevier GmbH. All rights reserved.

Impact of breeding region and season on the content of some trace elements and heavy metals in the hair of cows.

PubMed

Cygan-Szczegielniak, Dorota; Stanek, Magdalena; Giernatowska, Emilia; Janicki, Bogdan

2014-01-01

The aim of the research was to determine the effect of the season and the breeding region on the content of selected minerals (Zn, Cu, Mn, Fe, Pb, Cd) in the hair of dairy cows. The research material covered 114 Holstein-Friesian breed cows from three breeding centres in Poland, hereafterreferred to as A, B and C. Breeding centre A is located in Opolskie province, breeding centre B in Podlaskie province and breeding centre C in Kujawsko-Pomorskie province. The cows were kept in freestanding cowsheds with den boxes. Animal nutrition involved the use of the TMR system, considering division into nutrition groups. Hair was sampled in summer and in the period of winter and spring from the side of the body, directly behind the coastal arch. The Zn, Cu, Mn, Fe analysis was performed with atomic absorption spectrometry. The Pb and Cd content was assayed with the use of the electrothermal atomic absorption spectrometry. The results demonstrated the effect of season and breeding region on the level of the minerals and heavy metals assayed in the hair of cows being in the period of drying-off. The hair sampled in winter from cows from C demonstrated a higher concentration of most elements except for Fe than in material derived in summer. Hair sampled in winter from cows from the B centre showed higher Zn, Cu and Pb concentrations as compared with summer. Higher Cu, Mn, Fe and Pb concentrations were determined in hair sampled during winter from cows from A than in the material obtained in summer. The Cd content in the cow hair did not exceed the admissible norm, however, normal levels were exceeded for Pb in hair sampled in winter from cows from breeding centre C.

In vitro study of percutaneous absorption of aluminum from antiperspirants through human skin in the Franz™ diffusion cell.

PubMed

Pineau, Alain; Guillard, Olivier; Favreau, Frédéric; Marty, Marie-Hélène; Gaudin, Angeline; Vincent, Claire Marie; Marrauld, Annie; Fauconneau, Bernard; Marty, Jean-Paul

2012-05-01

Aluminum salts such as aluminum chlorohydrate (ACH) are known for use as an active antiperspirant agent that blocks the secretion of sweat. A local case report of hyperaluminemia in a woman using an aluminum-containing antiperspirant for 4 years raises the problem of transdermal absorption of aluminum (Al). Only a very limited number of studies have shown that the skin is an effective barrier to transdermal uptake of Al. In accordance with our analytical procedure, the aim of this study with an in vitro Franz™ diffusion cell was to measure aluminum uptake from three cosmetic formulations of antiperspirant: the base for an "aerosol" (38.5% of ACH), a "roll-on" emulsion (14.5% ACH), and a "stick" (21.2%), by samples of intact and stripped human skin (5 donors). The Al assays were performed by Zeeman Electrothermal Atomic Absorption Spectrophotometry (ZEAAS). Following contacts lasting 6, 12 and 24h, the Al assays showed only insignificant transdermal absorption of Al (≤0.07% of the quantity of Al deposited) and particularly low cutaneous quantities that varied according to the formulations (1.8 μg/cm² for "aerosol base" and "stick" - 0.5 μg/cm² for the "roll-on"). On stripped skin, for which only the "stick" formulation was tested, the measured uptake was significantly higher (11.50 μg/cm² versus 1.81 μg/cm² for normal skin). These results offer reassurance as regards to the use of antiperspirants for topical application of ACH-containing cosmetic formulations on healthy skin over a limited time span (24h). On the other hand, high transdermal Al uptake on stripped skin should compel antiperspirant manufacturers to proceed with the utmost caution. Copyright © 2012 Elsevier Inc. All rights reserved.

Inorganic selenium speciation analysis in Allium and Brassica vegetables by ionic liquid assisted liquid-liquid microextraction with multivariate optimization.

PubMed

Castro Grijalba, Alexander; Martinis, Estefanía M; Wuilloud, Rodolfo G

2017-03-15

A highly sensitive vortex assisted liquid-liquid microextraction (VA-LLME) method was developed for inorganic Se [Se(IV) and Se(VI)] speciation analysis in Allium and Brassica vegetables. Trihexyl(tetradecyl)phosphonium decanoate phosphonium ionic liquid (IL) was applied for the extraction of Se(IV)-ammonium pyrrolidine dithiocarbamate (APDC) complex followed by Se determination with electrothermal atomic absorption spectrometry. A complete optimization of the graphite furnace temperature program was developed for accurate determination of Se in the IL-enriched extracts and multivariate statistical optimization was performed to define the conditions for the highest extraction efficiency. Significant factors of IL-VA-LLME method were sample volume, extraction pH, extraction time and APDC concentration. High extraction efficiency (90%), a 100-fold preconcentration factor and a detection limit of 5.0ng/L were achieved. The high sensitivity obtained with preconcentration and the non-chromatographic separation of inorganic Se species in complex matrix samples such as garlic, onion, leek, broccoli and cauliflower, are the main advantages of IL-VA-LLME. Copyright © 2016 Elsevier Ltd. All rights reserved.

Deep eutectic liquid organic salt as a new solvent for liquid-phase microextraction and its application in ligandless extraction and preconcentraion of lead and cadmium in edible oils.

PubMed

Karimi, Mehdi; Dadfarnia, Shayessteh; Shabani, Ali Mohammad Haji; Tamaddon, Fatemeh; Azadi, Davood

2015-11-01

Deep eutectic liquid organic salt was used as the solvent and a liquid phase microextraction (DES-LPME) combined with electrothermal atomic absorption spectrometry (ETAAS) was developed for separation, preconcentration and determination of lead and cadmium in edible oils. A 4:1 mixture of deep eutectic solvent and 2% nitric acid (200 µL) was added to an oil sample. The mixture was vortexed and transferred into a water bath at 50 °C and stirred for 5 minutes. After the extraction was completed, the phases were separated by centrifugation, and the enriched analytes in the deep eutectic solvent phase were determined by ETAAS. Under optimized extraction conditions and for an oil sample of 28 g, enhancement factors of 198 and 195 and limits of detection (defined as 3 Sb/m) of 8 and 0. 2 ng kg(-1) were achieved for lead and cadmium respectively. The method was successfully applied to the determination of lead and cadmium in various edible oils. Copyright © 2015. Published by Elsevier B.V.

Inkjet printing of Chitlac-nanosilver--a method to create functional coatings for non-metallic bone implants.

PubMed

Nganga, Sara; Moritz, Niko; Kolakovic, Ruzica; Jakobsson, Kristina; Nyman, Johan O; Borgogna, Massimiliano; Travan, Andrea; Crosera, Matteo; Donati, Ivan; Vallittu, Pekka K; Sandler, Niklas

2014-10-22

Biostable fiber-reinforced composites, based on bisphenol-A-dimethacrylate and triethyleneglycoldimethacrylate thermoset polymer matrix reinforced with E-glass fibers have been successfully used in cranial reconstructions and the material has been approved for clinical use. As a further refinement of these implants, antimicrobial, non-cytotoxic coatings on the composites were created by an immersion procedure driven by strong electrostatic interactions. Silver nanoparticles (nAg) were immobilized in lactose-modified chitosan (Chitlac) to prepare the bacteriostatic coatings. Herein, we report the use of inkjet technology (a drop-on-demand inkjet printer) to deposit functional Chitlac-nAg coatings on the thermoset substrates. Characterization methods included scanning electron microscopy, scanning white light interferometry and electro-thermal atomic absorption spectroscopy. Inkjet printing enabled the fast and flexible functionalization of the thermoset surfaces with controlled coating patterns. The coatings were not impaired by the printing process: the kinetics of silver release from the coatings created by inkjet printing and conventional immersion technique was similar. Further research is foreseen to optimize printing parameters and to tailor the characteristics of the coatings for specific clinical applications.

Acidified pressurized hot water for the continuous extraction of cadmium and lead from plant materials prior to ETAAS

NASA Astrophysics Data System (ADS)

Morales-Muñoz, S.; Luque-García, J. L.; Luque de Castro, M. D.

2003-01-01

Acidified and pressurized hot water is proposed for the continuous leaching of Cd and Pb from plants prior to determination by electrothermal atomic absorption spectrometry. Beech leaves (a certified reference material—CRM 100—where the analytes were not certified) were used for optimizing the method by a multivariate approach. The samples (0.5 g) were subjected to dynamic extraction with water modified with 1% v/v HNO 3 at 250 °C as leachant. A kinetics study was performed in order to know the pattern of the extraction process. The method was validated with a CRM (olive leaves, 062 from the BCR) where the analytes had been certified. The agreement between the certified values and those found using the proposed method demonstrates its usefulness. The repeatability and within-laboratory reproducibility were 3.7 and 2.3% for Cd and 1.04% and 6.3% for Pb, respectively. The precision of the method, together with its efficiency, rapidity, and environmental acceptability, makes it a good alternative for the determination of trace metals in plant material.

Non-chromatographic speciation of chromium at sub-ppb levels using cloud point extraction in the presence of unmodified silver nanoparticles.

PubMed

López-García, Ignacio; Vicente-Martínez, Yesica; Hernández-Córdoba, Manuel

2015-01-01

The cloud point extraction (CPE) of silver nanoparticles (AgNPs) by Triton X-114 allows chromium (III) ions to be transferred to the surfactant-rich phase, where they can be measured by electrothermal atomic absorption spectrometry. Using 20 mL sample and 50 μL Triton X-114 (30% w/v), the enrichment factor was 1150, and calibration graphs were obtained in the 5-100 ng L(-1) chromium range in the presence of 5 µg L(-1) AgNPs. Speciation of trivalent and hexavalent chromium was achieved by carrying out two CPE experiments, one of them in the presence of ethylenediaminetetraacetate. While in the first experiment, in absence of the complexing agent, the concentration of total chromium was obtained, the analytical signal measured in the presence of this chemical allowed the chromium (VI) concentration to be measured, being that of chromium (III) calculated by difference. The reliability of the procedure was verified by using three standard reference materials before applying to water, beer and wine samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of mercury and arsenic from industrial effluents on the drinking water and comparison of the water quality of polluted and non-polluted areas: a case study of Peshawar and Lower Dir.

PubMed

Ishaq, M; Jan, F Akbar; Khan, Murad Ali; Ihsanullah, I; Ahmad, I; Shakirullah, M; Roohullah

2013-02-01

The purpose of the present study was to find out the sources of mercury and arsenic pollution of water in the industrial area of Peshawar, the capital of Khyber Pakhtunkhwa, Pakistan. Samples of effluents, mud, and water were collected from the target area (industrial area of Peshawar), the area of water supply source, and from the less polluted area, the Lower Dir district, as the control. Hg was determined by the cold vapor generation technique, while arsenic was determined using the electrothermal atomic absorption technique. Data of the water from the industrial area were compared with that of the source area, control area, as well as with the WHO and some international drinking water quality standards. The results show that some parameters, i.e., TDS, DO, pH, and hardness, were more than the permissible limits. Textile and glass industries were found to be the major sources of Hg and As pollution. Downstream dilution of these contaminants was also observed.

A new gold standard approach to characterize the transport of Si across cell membranes in animals.

PubMed

Garneau, Alexandre P; Marcoux, Andrée-Anne; Frenette-Cotton, Rachelle; Bélanger, Richard; Isenring, Paul

2018-01-11

Silicon (Si) is increasingly recognized as an essential trace element in animals, especially since the identification of mammalian Si transport systems and Si responsive genes not long ago. During many years, however, efforts to gain substantial insight into the biological role of this element in animals have achieved partial success due in part to the unavailability of validated protocols to study Si movement across biological membranes. To circumvent such limitations, we have developed a general transport assay in which cellular Si content was determined by automated electrothermal atomic absorption spectrophotometry. We have found this assay to provide great analytic sensitivity with Si detection thresholds of less than 1 µM, that is, below or very close to the concentration range of animal cells. We have also found this assay to provide valid and cost-effective determinations in Si transport studies while requiring workable quantities of samples. The protocol described here should thus become gold standard toward accelerated progress in the field of Si transport. © 2018 Wiley Periodicals, Inc.

A microextraction procedure based on a task-specific ionic liquid for the separation and preconcentration of lead ions from red lipstick and pine leaves.

PubMed

Saljooqi, Asma; Shamspur, Tayebeh; Mohamadi, Maryam; Afzali, Daryoush; Mostafavi, Ali

2015-05-01

First, the extraction and preconcentration of ultratrace amounts of lead(II) ions was performed using microliter volumes of a task-specific ionic liquid. The remarkable properties of ionic liquids were added to the advantages of microextraction procedure. The ionic liquid used was trioctylmethylammonium thiosalicylate, which formed a lead thiolate complex due to the chelating effect of the ortho-positioned carboxylate relative to thiol functionality. So, trioctylmethylammonium thiosalicylate played the roles of both chelating agent and extraction solvent simultaneously. Hence, there is no need to use a ligand. The main parameters affecting the efficiency of the method were investigated and optimized. Under optimized conditions, this approach showed a linear range of 2.0-24.0 ng/mL with a detection limit of 0.0010 ng/mL. The proposed method was applied to the extraction and preconcentration of lead from red lipstick and pine leaves samples prior to electrothermal atomic absorption spectroscopic determination. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Heavy metals in edible seaweeds commercialised for human consumption

NASA Astrophysics Data System (ADS)

Besada, Victoria; Andrade, José Manuel; Schultze, Fernando; González, Juan José

2009-01-01

Though seaweed consumption is growing steadily across Europe, relatively few studies have reported on the quantities of heavy metals they contain and/or their potential effects on the population's health. This study focuses on the first topic and analyses the concentrations of six typical heavy metals (Cd, Pb, Hg, Cu, Zn, total As and inorganic As) in 52 samples from 11 algae-based products commercialised in Spain for direct human consumption ( Gelidium spp.; Eisenia bicyclis; Himanthalia elongata; Hizikia fusiforme; Laminaria spp.; Ulva rigida; Chondrus crispus; Porphyra umbilicales and Undaria pinnatifida). Samples were ground, homogenised and quantified by atomic absorption spectrometry (Cu and Zn by flame AAS; Cd, Pb and total As by electrothermal AAS; total mercury by the cold vapour technique; and inorganic As by flame-hydride generation). Accuracy was assessed by participation in periodic QUASIMEME (Quality Assurance of Information in Marine Environmental Monitoring in Europe) and IAEA (International Atomic Energy Agency) intercalibration exercises. To detect any objective differences existing between the seaweeds' metal concentrations, univariate and multivariate studies (principal component analysis, cluster analysis and linear discriminant analysis) were performed. It is concluded that the Hizikia fusiforme samples contained the highest values of total and inorganic As and that most Cd concentrations exceeded the French Legislation. The two harvesting areas (Atlantic and Pacific oceans) were differentiated using both univariate studies (for Cu, total As, Hg and Zn) and a multivariate discriminant function (which includes Zn, Cu and Pb).

Nickel absorption and kinetics in human volunteers.

PubMed

Sunderman, F W; Hopfer, S M; Sweeney, K R; Marcus, A H; Most, B M; Creason, J

1989-05-01

Mathematical modeling of the kinetics of nickel absorption, distribution, and elimination was performed in healthy human volunteers who ingested NiSO4 drinking water (Experiment 1) or added to food (Experiment 2). Nickel was analyzed by electrothermal atomic absorption spectrophotometry in serum, urine, and feces collected during 2 days before and 4 days after a specified NiSO4 dose (12 micrograms of nickel/kg, n = 4; 18 micrograms of nickel/kg, n = 4; or 50 micrograms of nickel/kg, n = 1). In Experiment 1, each of the subjects fasted 12 hr before and 3 hr after drinking one of the specified NiSO4 doses dissolved in water; in Experiment 2, the respective subjects fasted 12 hr before consuming a standard American breakfast that contained the identical dose of NiSO4 added to scrambled eggs. Kinetic analyses, using a compartmental model, provided excellent goodness-of-fit for paired data sets from all subjects. Absorbed nickel averaged 27 +/- 17% (mean +/- SD) of the dose ingested in water vs 0.7 +/- 0.4% of the same dose ingested in food (a 40-fold difference); rate constants for nickel absorption, transfer, and elimination were not significantly influenced by the oral vehicle. The elimination half-time for absorbed nickel averaged 28 +/- 9 hr. Renal clearance of nickel averaged 8.3 +/- 2.0 ml/min/1.73 m2 in Experiment 1 and 5.8 +/- 4.3 ml/min/1.73 m2 in Experiment 2. This study confirms that dietary constituents profoundly reduce the bioavailability of Ni2+ for alimentary absorption; approximately one-quarter of nickel ingested in drinking water after an over-night fast is absorbed from the human intestine and excreted in urine, compared with only 1% of nickel ingested in food. The compartmental model and kinetic parameters provided by this study will reduce the uncertainty of toxicologic risk assessments of human exposures to nickel in drinking water and food.

Arsenic in marine tissues — The challenging problems to electrothermal and hydride generation atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Karadjova, Irina B.; Petrov, Panayot K.; Serafimovski, Ivan; Stafilov, Trajče; Tsalev, Dimiter L.

2007-03-01

Analytical problems in determination of arsenic in marine tissues are addressed. Procedures for the determination of total As in solubilized or extracted tissues with tetramethylammonium hydroxide and methanol have been elaborated. Several typical lyophilized tissues were used: NIST SRM 1566a 'Oyster Tissue', BCR-60 CRM 'Trace Elements in an Aquatic Plant ( Lagarosiphon major)', BCR-627 'Forms of As in Tuna Fish Tissue', IAEA-140/TM 'Sea Plant Homogenate', NRCC DOLT-1 'Dogfish Liver' and two representatives of the Black Sea biota, Mediterranean mussel ( Mytilus galloprovincialis) and Brown algae ( Cystoseira barbata). Tissues (nominal 0.3 g) were extracted in tetramethylammonium hydroxide (TMAH) 1 ml of 25% m/v TMAH and 2 ml of water) or 5 ml of aqueous 80% v/v methanol (MeOH) in closed vessels in a microwave oven at 50 °C for 30 min. Arsenic in solubilized or extracted tissues was determined by electrothermal atomic absorption spectrometry (ETAAS) after appropriate dilution (nominally to 25 ml, with further dilution as required) under optimal instrumental parameters (pyrolysis temperature 900 °C and atomization temperature 2100 °C) with 1.5 μg Pd as modifier on Zr-Ir treated platform. Platforms have been pre-treated with 2.7 μmol of zirconium and then with 0.10 μmol of iridium which served as a permanent chemical modifier in direct ETAAS measurements and as an efficient hydride sequestration medium in flow injection hydride generation (FI-HG)-ETAAS. TMAH and methanol extract 96-108% and 51-100% of As from CRMs. Various calibration approaches have been considered and critically evaluated. The effect of species-dependent slope of calibration graph or standard additions plot for total As determination in a sample comprising of several individual As species with different ETAAS behavior has been considered as a kind of 'intrinsic element speciation interference' that cannot be completely overcome by standard additions technique. Calibration by means of CRMs has given only semi-quantitative results. The limits of detection (3 σ) were in the range 0.5-1.2 mg kg - 1 As dry weight (wt.) for direct ETAAS analysis of extracts in both TMAH and MeOH. Within-run precision (RSD%) was 5-15% and 7-20% for TMAH and MeOH extracts at As levels 4-50 mg kg - 1 dry wt., respectively. The hydride active fraction of As species in extracts, i.e. the sum of toxicologically-relevant arsenic species (inorganic As(III), inorganic As(V), monomethylarsonate (MMA) and dimethylarsinate (DMA)) was determined by FI-HG-ETAAS in diluted tissue extracts. Arsine, monomethylarsine and dimethylarsine were generated from diluted TMAH and MeOH extracts in the presence of 0.06-0.09 mol l - 1 hydrochloric acid and 0.075 mol l - 1 L-cysteine. Collection, pyrolysis and atomization temperatures were 450, 500, 2100 and 2150 °C, respectively. The LODs for the determination of hydride forming fraction (arsenite + arsenate + MMA + DMA) in TMAH and MeOH extracts were in the range 0.003-0.02 mg kg - 1 As dry wt. Within-run precision (RSD%) was 3-12% and 3-7% for TMAH and methanol extracts at As levels 0.15-2.4 mg kg - 1 dry wt., respectively. Results for the hydride forming fraction of As in TMAH and MeOH extract as % from the certified value for total As (for CRMs) or vs. the total As in TMAH extract (for real marine samples) are generally in agreement.

Origin of colossal dielectric response in (In + Nb) co-doped TiO2 rutile ceramics: a potential electrothermal material.

PubMed

Ke, Shanming; Li, Tao; Ye, Mao; Lin, Peng; Yuan, Wenxiang; Zeng, Xierong; Chen, Lang; Huang, Haitao

2017-08-31

(In + Nb) co-doped TiO 2 (TINO) rutile is an emerging material with a colossal dielectric permittivity (CP) and a low dielectric loss over wide temperature and frequency ranges. The electrical inhomogeneous nature of TINO ceramics is demonstrated by direct local current probing with high-resolution conductive atomic force microscopy (cAFM). The CP response in TINO is found to originate from the electron-pinned defect dipole induced conductive cluster effect and the electrode effect. Two types of dielectric relaxations are simultaneously observed due to these two effects. With the given synthesis condition, we found TINO shows a highly leaky feature that impairs its application as a dielectric material. However, the fast-temperature-rising phenomenon found in this work may open a new door for TINO to be applied as a potential electrothermal material with high efficiency, oxidation-proof, high temperature stability, and energy saving.

The Association Between Serum Selenium Levels with Rheumatoid Arthritis.

PubMed

Yu, Na; Han, Fang; Lin, Xiaojun; Tang, Chun; Ye, Jinghua; Cai, Xiaoyan

2016-07-01

There are conflicting reports on the correlation between serum selenium (Se) levels with rheumatoid arthritis (RA). Through a meta-analysis approach, the aim of the present study is to clarify the relationship between serum Se levels with RA. We searched literatures that met our predefined criteria in PubMed, ScienceDirect, and OVID published as of September 2015. Ten eligible articles with 14 case-control studies involving 716 subjects were identified. Overall, pooled analysis indicated that subjects with RA had lower serum levels of Se than the healthy controls (standardized mean difference (SMD) = -1.347, 95 % confidence interval (CI) = [-1.872, -0.823], p < 0.001). Further subgroup analysis indicated that subjects with RA had lower serum Se levels than healthy controls in Europe (SMD = -1.063, 95 % CI = [-1.571, -0.556], p < 0.001) and Asia (SMD = -3.254, 95 % CI = [-4.687, -1.821], p < 0.001) but not in USA (SMD = -0.322, 95 % CI = [-0.657, 0.012], p = 0.059). The serum Se levels were lower in RA than healthy controls measured by graphite furnace atom absorption spectrometry (GFAAS) (SMD = -1.026, 95 % CI = [-1.522, -0.530], p < 0.001), electrothermal absorption spectrometry (EAS) (SMD = -1.197, 95 % CI = [-2.373, -0.020], p < 0.05), flame atomic absorption spectrophotometry (FAAS) (SMD = -0.681, 95 % CI = [-1.049, -0.313], p < 0.001), and inductively coupled plasma-mass spectrophotometer (ICP-MS) (SMD = -11.707, 95 % CI = [-15.189, -8.224], p < 0.001) but not by neutron activation analysis (NAA) (SMD = -0.674, 95 % CI = [-1.350, 0.003], p = 0.051). In conclusion, this meta-analysis supports a significant association between low serum Se concentration with RA. However, this finding needs further confirmation by a trans-regional multicenter study to obtain better understanding of causal relationship between serum Se with RA of different human races or regions.

Electrothermal Feedback and Absorption-Induced Open-Circuit-Voltage Turnover in Solar Cells

NASA Astrophysics Data System (ADS)

Ullbrich, Sascha; Fischer, Axel; Tang, Zheng; Ávila, Jorge; Bolink, Henk J.; Reineke, Sebastian; Vandewal, Koen

2018-05-01

Solar panels easily heat up upon intense solar radiation due to excess energy dissipation of the absorbed photons or by nonradiative recombination of charge carriers. Still, photoinduced self-heating is often ignored when characterizing lab-sized samples. For light-intensity-dependent measurements of the open-circuit voltage (Suns-VO C ), allowing us to characterize the recombination mechanism, sample heating is often not considered, although almost 100% of the absorbed energy is converted into heat. Here, we show that the frequently observed stagnation or even decrease in VOC at increasingly high light intensities can be explained by considering an effective electrothermal feedback between the recombination current and the open-circuit voltage. Our analytical model fully explains the experimental data for various solar-cell technologies, comprising conventional inorganic semiconductors as well as organic and perovskite materials. Furthermore, the model can be exploited to determine the ideality factor, the effective gap, and the temperature rise from a single Suns-VOC measurement at ambient conditions.

[Novel Hyphenated Techniques of Atomic Spectrometry for Metal Species Interaction with Biomolecules].

PubMed

Li, Yan; Yan, Xiu-ping

2015-09-01

Trace metals may be adopted by biological systems to assist in the syntheses and metabolic functions of genes (DNA and RNA) and proteins in the environment. These metals may be beneficial or may pose a risk to humans and other life forms. Novel hybrid techniques are required for studies on the interaction between different metal species and biomolecules, which is significant for biology, biochemistry, nutrition, agriculture, medicine, pharmacy, and environmental science. In recent years, our group dwells on new hyphenated techniques based on capillary electrophoresis (CE), electrothermal atomic absorption spectrometry (ETAAS), and inductively coupled plasma mass spectroscopy (ICP-MS), and their application for different metal species interaction with biomolecules such as DNA, HSA, and GSH. The CE-ETAAS assay and CE-ICP-MS assay allow sensitively probing the level of biomolecules such as DNA damage by different metal species and extracting the kinetic and thermodynamic information on the interactions of different metal species with biomolecules, provides direct evidences for the formation of different metal species--biomolecule adducts. In addition, the consequent structural information were extracted from circular dichroism (CD) and X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. The present works represent the most complete and extensive study to date on the interactions between different metal species with biomolecules, and also provide new evidences for and insights into the interactions of different metal species with biomolecules for further understanding of the toxicological effects of metal species.

The utilization of modified BCR three-step sequential extraction procedure for the fractionation of Cd, Cr, Cu, Ni, Pb and Zn in soil reference materials of different origins.

PubMed

Zemberyová, Mária; Barteková, Jana; Hagarová, Ingrid

2006-12-15

A modified three-step sequential extraction procedure for the fractionation of heavy metals, proposed by the Commission of the European Communities Bureau of Reference (BCR) has been applied to the Slovak reference materials of soils (soil orthic luvisols, soil rendzina and soil eutric cambisol), which represent pedologically different types of soils in Slovakia. Analyses were carried out by flame or electrothermal atomic absorption spectrometry (FAAS or ETAAS). The fractions extracted were: exchangeable (extraction step 1), reducible-iron/manganese oxides (extraction step 2), oxidizable-organic matter and sulfides (extraction step 3). The sum of the element contents in the three fractions plus aqua-regia extractable content of the residue was compared to the aqua-regia extractable content of the elements in the origin soils. The accuracy obtained by comparing the determined contents of the elements with certified values, using BCR CRM 701, certified for the extractable contents (mass fractions) of Cd, Cr, Cu, Ni, Pb and Zn in sediment following a modified BCR-three step sequential extraction procedure, was found to be satisfactory.

Separation of bismuth from gram amounts of thallium and silver by cation-exchange chromatography in nitric acid.

PubMed

Meintjies, E; Strelow, F W; Victor, A H

1987-04-01

Traces and small amounts of bismuth can be separated from gram amounts of thallium and silver by successively eluting these elements with 0.3M and 0.6M nitric acid from a column containing 13 ml (3 g) of AG50W-X4, a cation-exchanger (100-200 mesh particle size) with low cross-linking. Bismuth is retained and can be eluted with 0.2M hydrobromic acid containing 20% v/v acetone, leaving many other trace elements absorbed. Elution of thallium is quite sharp, but silver shows a small amount of tailing (less than 1 gmg/ml silver in the eluate) when gram amounts are present, between 20 and 80 mug of silver appearing in the bismuth fraction. Relevant elution curves and results for the analysis of synthetic mixtures containing between 50 mug and 10 mg of bismuth and up to more than 1 g of thallium and silver are presented, as well as results for bismuth in a sample of thallium metal and in Merck thallium(I) carbonate. As little as 0.01 ppm of bismuth can be determined when the separation is combined with electrothermal atomic-absorption spectrometry.

[The external quality assessment schemes for lead in blood organized by the French national agency for medicine and health product safety: a synthesis of 15 years of activity].

PubMed

Pineau, Alain; Otz, Jocelyne; Guillard, Olivier; Fauconneau, Bernard; Dumont, Gilles; François-Burg, Elisabeth

2014-01-01

In 1992, at the request of the French labor ministry following questions on the ability of medical biology laboratories to satisfactorily measure blood lead level (PbB), a national PbB quality control came into being. Only in 1996 did this external quality control include a number of laboratories sufficient to allow for a significant retrospective evaluation. After fifteen years (1996-2011), The French National Agency for Medicines and Health Products Safety wished to exploit the database collected. The number of participating laboratories went down from 73 to 41. On the other hand, the key finding pertained to the highly improved performance of the laboratories, which was associated with a spread decrease of the results over the entire range of tested PbBs (9 to 700 μg/L). Since 2006, we have observed increasing use of the inductively coupled plasma with mass spectrometry and decreasing use of electrothermal atomic absorption spectrometry. Provided that they rely on identical metrology expertise, the two analytical techniques lead to results on all the tested concentrations that are not statistically different.

Study of the migration phenomena of specific metals in canned tomato paste before and after opening. Validation of a new quality indicator for opened cans.

PubMed

Raptopoulou, Kalomoira G; Pasias, Ioannis N; Thomaidis, Nikolaos S; Proestos, Charalampos

2014-07-01

A method for the simultaneous determination of Cd-Pb, As-Cu, Cr-Ni and Fe-Mn in canned tomato paste samples by Electrothermal Atomic Absorption Spectrometry was developed and validated. The validation procedure was conducted according to the terms of the European regulation for the official control of contaminants in foods. The validated method was applied for the determination of these metals and metalloids in 13 different tomato paste samples and the results showed that Cd content was higher than the maximum permissible value of 0.050 mg kg(-1) as proposed in European Regulation (EC) No 1881/2006 concerning fresh fruits and vegetables. Furthermore, a new quality indicator was evaluated in order to provide information about tomato paste quality and the appropriate storage time of an opened canned tomato paste. Finally, a migration test was accomplished based on the calculation of mass balance and the comparison of the elemental content in canned tomato paste samples and in aseptic paper pack and it was proved that Fe and Pb were the main metals migrating in tomato paste samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Optimization of cloud point extraction and solid phase extraction methods for speciation of arsenic in natural water using multivariate technique.

PubMed

Baig, Jameel A; Kazi, Tasneem G; Shah, Abdul Q; Arain, Mohammad B; Afridi, Hassan I; Kandhro, Ghulam A; Khan, Sumaira

2009-09-28

The simple and rapid pre-concentration techniques viz. cloud point extraction (CPE) and solid phase extraction (SPE) were applied for the determination of As(3+) and total inorganic arsenic (iAs) in surface and ground water samples. The As(3+) was formed complex with ammonium pyrrolidinedithiocarbamate (APDC) and extracted by surfactant-rich phases in the non-ionic surfactant Triton X-114, after centrifugation the surfactant-rich phase was diluted with 0.1 mol L(-1) HNO(3) in methanol. While total iAs in water samples was adsorbed on titanium dioxide (TiO(2)); after centrifugation, the solid phase was prepared to be slurry for determination. The extracted As species were determined by electrothermal atomic absorption spectrometry. The multivariate strategy was applied to estimate the optimum values of experimental factors for the recovery of As(3+) and total iAs by CPE and SPE. The standard addition method was used to validate the optimized methods. The obtained result showed sufficient recoveries for As(3+) and iAs (>98.0%). The concentration factor in both cases was found to be 40.

Comparison of lung burdens of inhaled particles of rats exposed during the day or night

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hesseltine, G.R.; Wolff, R.K.; Hanson, R.L.

Inhalation studies frequently involve daytime exposures of nocturnal animals to toxicants. Such exposures may result in different respiratory tract depositions than would be obtained if rodents were exposed at night. Our study assessed the effect of night versus day exposures on lung burdens of particles inhaled by Fischer 344 rats. One group of 15 female rats was exposed to 0.3 micron volume median diameter particles of gallium oxide (Ga2O3) for 11.2 h during the day and a second group of 15 female rats was exposed to the same aerosol for 11.2 h at night. Gallium in the lungs at themore » end of exposure was measured by electrothermal atomic absorption spectrometry. Rats exposed during the night had significantly (p less than 0.05) higher lung burdens than day-exposed rats when burdens were expressed as either microgram Ga2O3/lung (mean +/- SD = 896 +/- 175 versus 698 +/- 150) or microgram Ga2O3/g lung (mean +/- SD = 683 +/- 134 versus 465 +/- 103). The greater amount of material in lungs of rats exposed at night probably reflected increased ventilation accompanying nocturnal activity.« less

High performance preconcentration of inorganic Se species by dispersive micro-solid phase extraction with a nanosilica-ionic liquid hybrid material

NASA Astrophysics Data System (ADS)

Llaver, Mauricio; Coronado, Eduardo A.; Wuilloud, Rodolfo G.

2017-12-01

A highly sensitive and efficient dispersive micro-solid phase extraction (D-μ-SPE) method was developed for inorganic Se speciation analysis. A novel ionic liquid (IL)-nanomaterial hybrid consisting of 1-dodecyl-3-methylimidazolium bromide-functionalized nanosilica was used for the efficient retention of Se(IV) complexed with ammonium pyrrolidine dithiocarbamate, followed by elution with an ethyl acetate/Triton X-114 mixture and determination by electrothermal atomic absorption spectroscopy. The Se(VI) species was selectively determined by difference between total inorganic Se and Se(IV) after pre-reduction. The IL-nanomaterial hybrid was characterized by Fourier transform infrared spectroscopy and transmission electronic microscopy. Likewise, Se(IV) sorption capacity of the retention material and maximum amount of IL loaded on its surface were determined. Several factors concerning the functionalization, extraction and elution steps were optimized, yielding a 100% extraction efficiency for Se(IV) under optimal conditions. A limit of detection of 1.1 ng L- 1, a relative standard deviation of 5.7% and a 110-fold enhancement factor were obtained. The D-μ-SPE method was successfully applied to several water samples from different origins and compositions, including rain, tap, underground, river and sea.

Bismuth knowledge during the Renaissance strengthened by its use in Italian lustres production

NASA Astrophysics Data System (ADS)

Padeletti, G.; Fermo, P.

The knowledge of bismuth during the XV and XVI centuries represents an open question since, according to some authors, this element was confused with lead, tin and silver. On the contrary, G. Agricola (1494-1555), the pioneer of mineralogical science in Europe, in his two works (De Natura Fossilium, Lib X, 1546 and Bermannus Sive De Re Metallica Dialogus, 1528) asserts that bismuth was considered as an element distinct from the other metals at that time. This question gave rise to some interest, and von Lippmann in 1930 wrote a treatise dealing with the history of bismuth between 1400 and 1800. In this work we present the results obtained on Italian and Hispano-Moresque shards studied by means of X-ray diffraction, atomic absorption spectrometry with electrothermal atomisation, inductively coupled plasma optical emission spectrometry and scanning electron microscopy. It seems that our work could provide a new and important contribution to this debate, because we found bismuth in lustre composition of Renaissance shards produced in central Italy. Furthermore, we found that it could also be considered as a discriminating element between Italian and Hispano-Moresque productions, useful to assess their origin.

Italian Renaissance and Hispano-Moresque lustre-decorated majolicas: imitation cases of Hispano-Moresque style in central Italy

NASA Astrophysics Data System (ADS)

Padeletti, G.; Fermo, P.

An investigation was carried out on Renaissance lustre-decorated majolica shards, found during excavations made in Umbria (central Italy) and defined by experts, on the ground of the surface decoration, as imitations of the Hispano-Moresque style. A comparison between this particular kind of samples, produced in central Italy, and some Hispano-Moresque lustre shards has been performed. The ceramic bodies as well as the lustred surfaces have been analysed by means of several techniques: inductively coupled plasma optical emission spectrometry, X-ray diffraction (XRD), atomic absorption spectrometry with electrothermal atomisation and scanning electron microscopy. By means of XRD analysis the presence of cosalite (Pb2Bi2S5) has been disclosed in the Italian lustre decorations but was not observed in the Hispano-Moresque ones. A hypothesis has been made, considering bismuth as a discriminating element, between lustres produced in central Italy and the Hispano-Moresque ones. We thought that the Italian artisans were able to manage the use of bismuth. Therefore a recipe, quite similar to the one employed by the Spanish artisans, was used by the Italian ceramists if their aim was to imitate the Hispano-Moresque style.

Column leaching and sorption experiments to assess the mobility of potentially toxic elements in industrially contaminated land.

PubMed

Anderson, P; Davidson, C M; Duncan, A L; Littlejohn, D; Ure, A M; Garden, L M

2000-06-01

Made-up ground collected from layers of a trial pit excavated on a former industrial site was treated with artificial rainwater in a series of column leaching and sorption experiments. Metal mobility and the ability of various layers of material obtained from the pit to act as sources or sinks of potentially toxic elements were assessed. Samples from different layers varied in their abilities to raise the pH of rainwater applied at pH 3.5 and 4.3, and this was reflected in the amounts of metals mobilised by the rainwater as it percolated through the soil column. Material from the top two layers of the pit released cadmium, copper, manganese, lead, nickel and zinc to the aqueous phase, but the lower layers, with higher buffering capacity, were able to resist acidification even when the equivalent of 12 months' rainfall (western UK) was applied. Column sorption experiments confirmed the ability of material from layer 4 (48-50 cm) to take up copper, manganese and zinc. Metals were determined in the leachates by flame and electrothermal atomic absorption spectrometry and principle anions by ion chromatography.

A simple, rapid and green ultrasound assisted and ionic liquid dispersive microextraction procedure for the determination of tin in foods employing ETAAS.

PubMed

Tuzen, Mustafa; Uluozlu, Ozgur Dogan; Mendil, Durali; Soylak, Mustafa; Machado, Luana O R; Dos Santos, Walter N L; Ferreira, Sergio L C

2018-04-15

This paper proposes a simple, rapid and green ultrasound assisted and ionic liquid dispersive microextraction procedure using pyrocatechol violet (PV) as complexing reagent and 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide [C 6 MIM][Tf 2 N] as ionic liquid for the detection of tin employing electrothermal atomic absorption spectrometry (ETAAS). The optimization step was performed using a two-level full factorial design involving the following factors: pH of the working media, amount reagents, ionic liquid volume and extraction time and the chemometric response was tin recovery. The procedure allowed the determination of tin with limits of detection and quantification of 3.4 and 11.3 ng L -1 , respectively. The relative standard deviation was 4.5% for a tin solution of 0.50 µg L -1 . The validation method was confirmed by analysis of rice flour certified reference material. The method was applied for the quantification of tin in several food samples. The concentration range found varied from 0.10 to 1.50 µg g -1 . Copyright © 2017 Elsevier Ltd. All rights reserved.

Speciation of Cr(VI) in environmental samples in the vicinity of the ferrochrome smelter.

PubMed

Sedumedi, Hilda N; Mandiwana, Khakhathi L; Ngobeni, Prince; Panichev, Nikolay

2009-12-30

The impact of ferrochrome smelter on the contamination of its environment with toxic hexavalent chromium, Cr(VI), was assessed by analyzing smelter dusts, soil, grass and tree barks. For the separation of Cr(VI) from Cr(III), solid samples were treated with 0.1M Na(2)CO(3) and filtered through hydrophilic PDVF 0.45 microm filter prior to the determination of Cr(VI) by electrothermal atomic absorption spectrometry (ET-AAS). Ferrochrome smelter dust was found to contain significant levels of Cr(VI), viz. 43.5 microg g(-1) (cyclone dust), 2710 microg g(-1) (fine dust), and 7800 microg g(-1) (slimes dust) which exceeded the maximum acceptable risk concentration (20 microg g(-1)). The concentration of Cr(VI) in environmental samples of grass (3.4+/-0.2), soil (7.7+/-0.2), and tree bark (11.8+/-1.2) collected in the vicinity of the chrome smelter were higher as compared with the same kind of samples collected from uncontaminated area. The results of the investigation show that ferrochrome smelter is a source of environmental pollution with contamination factors of Cr(VI) ranging between 10 and 50.

Electrothermal debonding of ceramic brackets. An in vitro study.

PubMed

Brouns, E M; Schopf, P M; Kocjancic, B

1993-04-01

Two different kinds of devices for electrothermal debonding of ceramic brackets are evaluated. Thirty human premolars were bonded with two types of ceramic brackets. Both devices were tested for electrothermal removal of the two bracket types. The pulpal wall temperature increase during electrothermal debonding was recorded in vitro under various circumstances. After debonding, the fracture site was located. The data were compared to the temperature rise after simulated exposure of the teeth to warm beverages. Irreversible pulp damage due to electrothermal debonding of ceramic brackets with both instruments is not to be expected because the obtained results stayed below established primate threshold temperatures and significantly below that of the stimulated control groups. A significant difference was noted when air cooling was initiated during electrothermal debonding. Fracture site location was significantly different in the two ceramic bracket types after electrothermal debonding.

Transition-edge sensor with enhanced electrothermal feedback for cryogenic particle detection

DOEpatents

Nam, Sae Woo; Cabrera, Blas

2001-01-01

A superconducting transition-edge sensor with an electrothermal-feedback circuit, a heat sink thermally coupled thereto, a bias-feedback circuit electrically coupled with the electrothermal feedback circuit, and a current sensor electrically coupled with the bias-feedback circuit and inductively coupled with the electrothermal-feedback circuit.

Grafting 3-mercaptopropyl trimethoxysilane on multi-walled carbon nanotubes surface for improving on-line cadmium(II) preconcentration from water samples.

PubMed

Corazza, Marcela Zanetti; Somera, Bruna Fabrin; Segatelli, Mariana Gava; Tarley, Cesar Ricardo Teixeira

2012-12-01

In the present study, the performance of multi-walled carbon nanotubes (MWCNTs) grafted with 3-mercaptopropyltrimethoxysilane (3-MPTMS), used as a solid phase extractor for Cd(2+) preconcentration in a flow injection system coupled to flame atomic absorption spectrometry (FAAS), was evaluated. The procedure involved the preconcentration of 20.0 mL of Cd(2+) solution at pH 7.5 (0.1 mol L(-1) buffer phosphate) through 70 mg of 3-MPTMS-grafted MWCNTs packed into a minicolumn at 6.0 mL min(-1). The elution step was carried out with 1.0 mol L(-1) HCl. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to estimate the extent of the MWCNT chemical modification. The 3-MPTMS-grafted MWCNTs provided a 1.68 times improvement in the sensitivity of the Cd(2+) FAAS determination compared to the unsilanized oxidized MWCNTs. The following parameters were obtained: preconcentration factor of 31.5, consumptive index of 0.635 mL, sample throughput of 14 h(-1), and concentration efficiency of 9.46 min(-1). The analytical curve was constructed in the range of 1.0-60.0 μg L(-1) (r=0.9988), and the detection and quantification limits were found to be 0.15 μg L(-1) and 0.62 μg L(-1), respectively. Different types of water samples and cigarette sample were successfully analyzed, and the results were compared using electrothermal atomic absorption spectrometry (ETAAS) as reference technique. In addition, the accuracy of proposed method was also checked by analysis of certified reference material NIST SRM 1573a (tomato leaves) and standard reference material NIST SRM 1643e (trace elements in natural waters). Copyright © 2012 Elsevier B.V. All rights reserved.

Visible light emission measurements from a dense electrothermal launcher plasma

NASA Astrophysics Data System (ADS)

Hankins, O. E.; Bourham, M. A.; Earnhart, J.; Gilligan, J. G.

1993-01-01

Measurements of the visible light emission from dense, weakly non-ideal plasmas have been performed on the experimental electrothermal launcher device 'SIRENS'. The plasma is created by the ablation or a Lexan insulator in the source, which then flows through a cylindrical barrel which serves as the material sample. Visible light emission spectra have been observed both in-bore and from the muzzle flash or the barrel, and from the flash or the source. Due to high plasma opacity (the plasma emits as a near blackbody) and absorption by the molecular components of the vapor shield, the hotter core or the arc has been difficult to observe. Recent measurements along the axis or the device indicate time-averaged plasma temperatures in the barrel or about 1 eV for lower energy shots, which agree with experimental measurements of the average heat flux and plasma conductivity along the barrel. Measurements or visible emission from the source indicate time averaged temperatures of 1 to 2 eV which agree with the theoretical estimates derived from ablated mass measurements and calculated estimates derived from plasma conductivity measurements.

Content and bioaccessibility of aluminium in duplicate diets from southern Spain.

PubMed

Cabrera-Vique, Carmen; Mesías, Marta

2013-08-01

Aluminium is found naturally in foods and beverages, but levels increase notably during processing, packaging, storage, and cooking, as a consequence of its presence in food additives and the wide use of aluminium utensils and vessels. Dietary intake of Al was estimated in 2 population groups in southern Spain (families and university students) in a duplicate diet sampling study. Diets were sampled for 7 consecutive days, and Al was determined in acid-mineralized samples with electrothermal atomization-atomic absorption spectrometry (ETA-AAS). Mean values for Al intake were 2.93 and 1.01 mg/d in families and students, respectively, ranging from 0.12 to 10.00 mg/d. Assuming an average adult weight of 60 kg, the mean dietary exposures to aluminium were 0.34 and 0.12 mg/kg body weight/week in these groups, which amounted to 17% and 6% of the 2 mg/kg body weight estimated as the tolerable weekly intake by the Joint FAO/WHO Expert Committee on Food Additives. Bioaccessibility of dietary Al tested with in vitro studies ranged from 0.30 to 17.26% (absorbable fraction). The highest aluminium intakes were observed in subjects consuming diets with a low adherence to the Mediterranean diet, which were associated to high consumption of processed and canned food. On the contrary, subjects consuming diets with a high adherence to the Mediterranean diet patterns showed the lowest Al intakes. The present findings are useful for giving both a reliable estimate of total aluminium dietary intake and tolerable intake levels according to usual dietary habits. © 2013 Institute of Food Technologists®

A bibliography of electrothermal thruster technology, 1984

NASA Technical Reports Server (NTRS)

Sovey, J. S.; Hardy, T. L.; Englehart, M.

1986-01-01

Electrothermal propulsion concepts are briefly discussed as an introduction to a bibliography and author index. Nearly 700 citations are given for resistojets, thermal arcjets, pulsed electrothermal thrusters, microwave heated devices, solar thermal thrusters, and laser thermal thrusters.

Current technology in ion and electrothermal propulsion

NASA Technical Reports Server (NTRS)

Finke, R. C.; Murch, C. K.

1973-01-01

High performance propulsion devices, such as electrostatic ion engines and electrothermal thrusters, are achieving wide user acceptance. The current technology and projected development trends in the areas of ion and electrothermal propulsion systems and components are surveyed.

Electrothermal instability growth in magnetically driven pulsed power liners

NASA Astrophysics Data System (ADS)

Peterson, Kyle J.; Sinars, Daniel B.; Yu, Edmund P.; Herrmann, Mark C.; Cuneo, Michael E.; Slutz, Stephen A.; Smith, Ian C.; Atherton, Briggs W.; Knudson, Marcus D.; Nakhleh, Charles

2012-09-01

This paper explores the role of electro-thermal instabilities on the dynamics of magnetically accelerated implosion systems. Electro-thermal instabilities result from non-uniform heating due to temperature dependence in the conductivity of a material. Comparatively little is known about these types of instabilities compared to the well known Magneto-Rayleigh-Taylor (MRT) instability. We present simulations that show electrothermal instabilities form immediately after the surface material of a conductor melts and can act as a significant seed to subsequent MRT instability growth. We also present the results of several experiments performed on Sandia National Laboratories Z accelerator to investigate signatures of electrothermal instability growth on well characterized initially solid aluminum and copper rods driven with a 20 MA, 100 ns risetime current pulse. These experiments show excellent agreement with electrothermal instability simulations and exhibit larger instability growth than can be explained by MRT theory alone.

21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Atomic absorption spectrophotometer for clinical... Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification. An atomic absorption spectrophotometer for clinical use is a device intended to identify and measure...

21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Atomic absorption spectrophotometer for clinical... Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification. An atomic absorption spectrophotometer for clinical use is a device intended to identify and measure...

21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Atomic absorption spectrophotometer for clinical... Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification. An atomic absorption spectrophotometer for clinical use is a device intended to identify and measure...

21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Atomic absorption spectrophotometer for clinical... Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification. An atomic absorption spectrophotometer for clinical use is a device intended to identify and measure...

ET AAS evaluation of the stability and pH-sensitivity of, pH-sensitive stealth liposomes containing cisplatin in mouse plasma.

PubMed

Vieira, F P; Mesquita, T L; Lara, P C P; Ramaldes, G A; Beinner, M A; Silva, J B B; Oliveira, M C; Silveira, J N

2013-10-01

In this work, stability and the pH-sensitivity of pH-sensitive stealth liposomes containing cisplatin exposed to plasma medium and their subsequent responses to pH modifications were evaluated. A method to determine platin in mouse plasma by electrothermal atomic absorption spectroscopy (ET AAS) was developed and validated. At first, a comparative study of sample preparation treatments with basic, acidic, and acidic added with Triton X-100 as a modifier was done. The best treatment was obtained with HCl 3% (v/v). The ET AAS method with acid treatment presented linearity at a range of 10-160 ng Pt/mL. The limits of detection (LOD) was 3.1 ng/mL Pt for acid treatment, while the limit quantification (LOQ) was 10 ng/mL Pt. The acid treatment presented good repeatability (VC<15.0%) and recovery close to 100%. This treatment was chosen for subsequent studies due to its best value of repeatability, recovery, LOD and lowest cost. pH-sensitive stealth liposomes, containing cisplatin, demonstrated low stability and poor response to pH variation after plasma incubation. These findings suggest that further studies are needed to improve liposome formulation i.e., to reduce its size. Copyright © 2013 Elsevier B.V. All rights reserved.

Determination of arsenic species in rice samples using CPE and ETAAS.

PubMed

Costa, Bruno Elias Dos Santos; Coelho, Nívia Maria Melo; Coelho, Luciana Melo

2015-07-01

A highly sensitive and selective procedure for the determination of arsenate and total arsenic in food by electrothermal atomic absorption spectrometry after cloud point extraction (ETAAS/CPE) was developed. The procedure is based on the formation of a complex of As(V) ions with molybdate in the presence of 50.0 mmol L(-1) sulfuric acid. The complex was extracted into the surfactant-rich phase of 0.06% (w/v) Triton X-114. The variables affecting the complex formation, extraction and phase separation were optimized using factorial designs. Under the optimal conditions, the calibration graph was linear in the range of 0.05-10.0 μg L(-1). The detection and quantification limits were 10 and 33 ng L(-1), respectively and the corresponding value for the relative standard deviation for 10 replicates was below 5%. Recovery values of between 90.8% and 113.1% were obtained for spiked samples. The accuracy of the method was evaluated by comparison with the results obtained for the analysis of a rice flour sample (certified material IRMM-804) and no significant difference at the 95% confidence level was observed. The method was successfully applied to the determination of As(V) and total arsenic in rice samples. Copyright © 2015 Elsevier Ltd. All rights reserved.

Localized accumulation of lead within and among bones from lead-dosed goats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cretacci, Yan; Department of Environmental Health Sciences, School of Public Health, The University at Albany, P.O. Box 509, Albany, NY 12201-0509; Parsons, Patrick J., E-mail: pparsons@wadsworth.org

2010-01-15

The principal aim of this study was to gain a better understanding of where lead (Pb) accumulates and how it is distributed, within the bones of dosed goats. Adult goats were periodically dosed with Pb over a number of years for the primary purpose of producing blood pools containing endogenously bound Pb, for the New York State Blood Lead Proficiency Testing Program. Bone samples (e.g., primarily tibia, femur, humerus, and radius) were collected post-mortem from 11 animals and were analyzed for Pb content by acid digestion and electrothermal atomic absorption spectrometry (ETAAS or GFAAS). Average tibia Pb levels were foundmore » to correlate strongly with the cumulative Pb dose (r{sup 2}=0.81). However, the concentration of Pb in different bones and even within a small area of the same bone varied tremendously. Blood-rich trabecular (spongy) bone, such as the patella and calcaneus, were much more enriched in Pb than was cortical (compact) bone. In some dosed animals, the Pb concentration in the tibia was markedly higher at the proximal and distal ends of the bone compared to the mid-shaft. The implications of these findings with regard to the noninvasive measurement of lead in bone by XRF methods are discussed.« less

Surfactant-assisted emulsification dispersive liquid-liquid microextraction using 2-thenoyltrifluoroacetone as a chelating agent coupled with electrothermal atomic absorption spectrometry for the speciation of chromium in water and rice samples.

PubMed

Dokpikul, Nattawut; Chaiyasith, Wipharat Chuachuad; Sananmuang, Ratana; Ampiah-Bonney, Richmond J

2018-04-25

A novel method was developed by SAE-DLLME for chromium speciation in water and rice samples using 2-thenoyltrifluoroacetone (TTA) as a chelating reagent by ETAAS. The speciation of Cr(III) and Cr(VI) was achieved by complexation of Cr(III)-TTA and the total Cr was measured after reduction of Cr(VI) to Cr. The calibration graph was linear in the range of 0.02-2.50 µg L -1 , with a detection limit of 0.0052 µg L -1 . The %RSD was in range of 2.90-3.30% at 0.5, 1.5 and 2.5 µg L -1 of Cr(III), n = 5 and the EF was 54.47. The method was applied to chromium speciation and total chromium determination in real samples and gave recoveries in the range of 96.2-103.5% and 97.1-102.7% for Cr(III) and Cr(VI) in water samples and 93.7-103.5% of total Cr in rice samples. The accuracy of the method was evaluated by analysis of SRM 1573a with good agreement compared to the certified value. Copyright © 2017 Elsevier Ltd. All rights reserved.

Cloud point extraction of vanadium in pharmaceutical formulations, dialysate and parenteral solutions using 8-hydroxyquinoline and nonionic surfactant.

PubMed

Khan, Sumaira; Kazi, Tasneem G; Baig, Jameel A; Kolachi, Nida F; Afridi, Hassan I; Wadhwa, Sham Kumar; Shah, Abdul Q; Kandhro, Ghulam A; Shah, Faheem

2010-10-15

A cloud point extraction (CPE) method has been developed for the determination of trace quantity of vanadium ions in pharmaceutical formulations (PF), dialysate (DS) and parenteral solutions (PS). The CPE of vanadium (V) using 8-hydroxyquinoline (oxine) as complexing reagent and mediated by nonionic surfactant (Triton X-114) was investigated. The parameters that affect the extraction efficiency of CPE, such as pH of sample solution, concentration of oxine and Triton X-114, equilibration temperature and time period for shaking were investigated in detail. The validity of CPE of V was checked by standard addition method in real samples. The extracted surfactant-rich phase was diluted with nitric acid in ethanol, prior to subjecting electrothermal atomic absorption spectrometry. Under these conditions, the preconcentration of 50 mL sample solutions, allowed raising an enrichment factor of 125-fold. The lower limit of detection obtained under the optimal conditions was 42 ng/L. The proposed method has been successfully applied to the determination of trace quantity of V in various pharmaceutical preparations with satisfactory results. The concentration ranges of V in PF, DS and PS samples were found in the range of 10.5-15.2, 0.65-1.32 and 1.76-6.93 microg/L, respectively. 2010 Elsevier B.V. All rights reserved.

Serum metal ion levels after rotating-hinge knee arthroplasty: comparison between a standard device and a megaprosthesis.

PubMed

Friesenbichler, Joerg; Maurer-Ertl, Werner; Sadoghi, Patrick; Lovse, Thomas; Windhager, Reinhard; Leithner, Andreas

2012-03-01

The effects of systemic metal ion exposure in patients with implants made of common prosthetic alloys continue to be a matter of concern. The aim of the study was to determine the measurement values of cobalt (Co), chromium (Cr) and molybdenum (Mo) in serum following rotating-hinge knee arthroplasty. Blood was taken from 25 patients [mean follow-up 35 (range nine to 67) months] treated with megaprostheses (n=17) or standard rotating-hinge devices (n=8) and analysed using electrothermal graphite furnace atomic absorption spectrometry (ET-ASS). Determining the concentrations of metal ions following rotating-hinge knee arthroplasty revealed increments for Co and Cr but not Mo. Metal ion release was significantly higher in patients with megaprostheses compared to a standard rotating-hinge knee device (Co p=0,024; Cr p=0.025). The authors believe there might be an additional metal ion release from the surface of the prosthesis and not only from the articulating surfaces because, in cases of rotating-hinge knee prosthesis, there is a metal-on-polyethylene articulation and not a direct metal-on-metal junction. Nevertheless, long-term studies are required to determine adverse effects of Co, Cr and Mo following total hip replacement and total knee arthroplasty.

Evaluation of chromium, cobalt and manganese in biological samples (scalp hair, blood, and urine) of Pakistani viral hepatitis (A-E) patients and controls.

PubMed

Afridi, Hassan Imran; Kazi, Tasneem Gul; Kazi, Naveed; Naeemullah; Arain, Sadaf Sadia; Brahman, Kapil Dev; Wadhwa, Sham Kumar

2013-01-01

The aim of the present study was to compare the level of chromium (Cr), cobalt (Co), and manganese (Mn) in biological samples (blood, urine, and scalp hair) of patients suffering from different types of viral hepatitis (A, B, C, D, and E; n = 521) of both genders, ages ranging from 31 - 45 years. For comparative study, 255 age-matched control subjects of both genders residing in the same city were selected as referents. The digests of all biological samples were analysed for Cr, Co, and Mn by electrothermal atomic absorption spectrometry (ETAAS). The validity and accuracy of the methodology was checked by using certified reference materials (CRMs) and compared with those values obtained by conventional wet acid digestion method on same CRMs. The results of this study showed that the mean values of Cr, Co, and Mn were higher in blood and scalp hair samples of hepatitis patients than in age-matched control subjects. The urinary levels of these elements were found to be higher in the hepatitis patients than in the age-matched healthy controls (p <0.001). These results are consistent with literature-reported data, confirming that the overload of these trace elements can directly cause lipid peroxidation and eventually hepatic damage.

Application of a thiourea-containing task-specific ionic liquid for the solid-phase extraction cleanup of lead ions from red lipstick, pine leaves, and water samples.

PubMed

Saljooqi, Asma; Shamspur, Tayebeh; Mohamadi, Maryam; Mostafavi, Ali

2014-07-01

Here, task-specific ionic liquid solid-phase extraction is proposed for the first time. In this approach, a thiourea-functionalized ionic liquid is immobilized on the solid sorbent, multiwalled carbon nanotubes. These modified nanotubes packed into a solid-phase extraction column are used for the selective extraction and preconcentration of ultra-trace amounts of lead(II) from aqueous samples prior to electrothermal atomic absorption spectroscopy determination. The thiourea functional groups act as chelating agents for lead ions retaining them and so, give the selectivity to the sorbent. Elution of the retained ions can be performed using an acidic thiourea solution. The effects of experimental parameters including pH of the aqueous solution, type and amount of eluent, and the flow rates of sample and eluent solutions on the separation efficiency are investigated. The linear dependence of absorbance of lead on its concentration in the initial solution is in the range of 0.5-40.0 ng/mL with the detection limit of 0.13 ng/mL (3(Sb)/m, n = 10). The proposed method is applicable to the analysis of red lipstick, pine leaves, and water samples for their lead contents. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of gold in geologic materials by solvent extraction and atomic-absorption spectrometry

USGS Publications Warehouse

Huffman, Claude; Mensik, J.D.; Riley, L.B.

1967-01-01

The two methods presented for the determination of traces of gold in geologic materials are the cyanide atomic-absorption method and the fire-assay atomic-absorption method. In the cyanide method gold is leached with a sodium-cyanide solution. The monovalent gold is then oxidized to the trivalent state and concentrated by extracting into methyl isobutyl ketone prior to estimation by atomic absorption. In the fire-assay atomic-absorption method, the gold-silver bead obtained from fire assay is dissolved in nitric and hydrochloric acids. Gold is then concentrated by extracting into methyl isobutyl ketone prior to determination by atomic absorption. By either method concentrations as low as 50 parts per billion of gold can be determined in a 15-gram sample.

[Estimation of maximum acceptable concentration of lead and cadmium in plants and their medicinal preparations].

PubMed

Zitkevicius, Virgilijus; Savickiene, Nijole; Abdrachmanovas, Olegas; Ryselis, Stanislovas; Masteiková, Rūta; Chalupova, Zuzana; Dagilyte, Audrone; Baranauskas, Algirdas

2003-01-01

Heavy metals (lead, cadmium) are possible dashes which quantity is defined by the limiting acceptable contents. Different drugs preparations: infusions, decoctions, tinctures, extracts, etc. are produced using medicinal plants. The objective of this research was to study the impurities of heavy metals (lead, cadmium) in medicinal plants and some drug preparations. We investigated liquid extracts of fruits Crataegus monogyna Jacq. and herbs of Echinacea purpurea Moench., tinctures--of herbs Leonurus cardiaca L. The raw materials were imported from Poland. Investigations were carried out in cooperation with the Laboratory of Antropogenic Factors of the Institute for Biomedical Research. Amounts of lead and cadmium were established after "dry" mineralisation using "Perkin-Elmer Zeeman/3030" model electrothermic atomic absorption spectrophotometer (ETG AAS/Zeeman). It was established that lead is absorbed most efficiently after estimation of absorption capacity of cellular fibers. About 10.73% of lead crosses tinctures and extracts, better cadmium--49.63%. Herbs of Leonurus cardiaca L. are the best in holding back lead and cadmium. About 14.5% of lead and cadmium crosses the tincture of herbs Leonurus cardiaca L. We estimated the factors of heavy metals (lead, cadmium) in the liquid extracts of Crataegus monogyna Jacq. and Echinacea purpurea Moench., tincture of Leonurus cardiaca L. after investigations of heavy metals (lead, cadmium) in drugs and preparations of it. The amounts of heavy metals (lead, cadmium) don't exceed the allowable norms in fruits of Crataegus monogyna Jacq., herbs of Leonurus cardiaca L. and Echinacea purpurea Moench. after estimation of lead and cadmium extraction factors, the maximum of acceptable daily intake and the quantity of drugs consumption in day.

Atomic force microscope based on vertical silicon probes

NASA Astrophysics Data System (ADS)

Walter, Benjamin; Mairiaux, Estelle; Faucher, Marc

2017-06-01

A family of silicon micro-sensors for Atomic Force Microscope (AFM) is presented that allows to operate with integrated transducers from medium to high frequencies together with moderate stiffness constants. The sensors are based on Micro-Electro-Mechanical-Systems technology. The vertical design specifically enables a long tip to oscillate perpendicularly to the surface to be imaged. The tip is part of a resonator including quasi-flexural composite beams, and symmetrical transducers that can be used as piezoresistive detector and/or electro-thermal actuator. Two vertical probes (Vprobes) were operated up to 4.3 MHz with stiffness constants 150 N/m to 500 N/m and the capability to oscillate from 10 pm to 90 nm. AFM images of several samples both in amplitude modulation (tapping-mode) and in frequency modulation were obtained.

Development of Electrothermal Pulsed Plasma Thrusters for Osaka-Institute-of-Technology Electric-Rocket-Engine onboard Small Space Ship

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ishii, Yushuke; Yamamoto, Tsuyoshi; Yamada, Minetsugu

2008-12-31

The Project of Osaka-Institute-of-Technology Electric-Rocket-Engine onboard Small Space Ship (PROITERES) was started at Osaka Institute of Technology. In PROITERES, a 10-kg small satellite with electrothermal pulsed plasma thrusters (PPTs), named JOSHO, will be launched in 2010. The main mission is powered flight of small satellite by electric thruster itself. Electrothermal PPTs were studied with both experiments and numerical simulations. An electrothermal PPT with a side-fed propellant feeding mechanism achieved a total impulse of 3.6 Ns with a repetitive 10000-shot operation. An unsteady numerical simulation showed the existence of considerable amount of ablation delaying to the discharge. However, it was alsomore » shown that this phenomenon should not be regarded as the 'late time ablation' for electrothermal PPTs.« less

40 CFR Appendix A to Subpart C of... - Alternative Testing Methods Approved for Analyses Under the Safe Drinking Water Act

Code of Federal Regulations, 2010 CFR

2010-07-01

... Absorption D 3697-07 Atomic Absorption; Furnace 3113 B Axially viewed inductively coupled plasma-atomic... C Hydride Atomic Absorption 3114 B D 2972-08 B Axially viewed inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2. Barium Inductively Coupled Plasma 3120 B Atomic...

The effect on syringe performance of fluid storage and repeated use: implications for syringe pumps.

PubMed

Capes, D F; Herring, D; Sunderland, V B; McMillan, D; McDonald, C

1996-01-01

Syringe stiction has been reported to cause syringe pump malfunction, hence the effect on syringe performance of syringe use and the formulations used in the syringe were investigated. The force required for syringe plunger motion (at 2.5 mm min-1), when filled with soybean oil emulsion (SBOE) and with water, and the extraction of silicone oil from syringes by these fluids, were measured for Primo, Talus and Terumo 10 mL, and Terumo 50 mL syringes. The breakloose, average extrusion and maximum force required to maintain plunger motion increased after storage of SBOE for 7 days in all syringes tested (p < 0.05). The storage of water increased the breakloose force of all syringes, but only increased the maximum force of Talus syringes, and both the average extrusion and maximum forces of Terumo 10 mL syringes. The mechanism for this is most likely swelling of the elastomer of the piston due to sorption of fluid. The force was found to increase logarithmically with repeated syringe use. Electrothermal atomization atomic absorption spectroscopy was used to measure the silicone oil content of syringe extractions. Three extractions were performed: repeated flushing, vigorous washing, and storage for 7 days with occasional agitation. Up to 69.4% of the silicone oil present in the syringes was extracted with both water and SBOE when they were stored or washed. In contrast to water, SBOE also extracted the lubricant when the syringe was filled and flushed immediately. If syringes are refilled, stored filled before use, or used over a prolonged period, particularly with a SBOE formulation, syringe striction may occur during infusion with a syringe pump.

Mercury in the gold mining district of San Martin de Loba, South of Bolivar (Colombia).

PubMed

Olivero-Verbel, Jesus; Caballero-Gallardo, Karina; Turizo-Tapia, Alexi

2015-04-01

Gold mining is responsible for most Hg pollution in developing countries. The aims of this study were to assess the levels of total Hg (T-Hg) in human hair, fish, water, macrophyte, and sediment samples in the gold mining district of San Martin de Loba, Colombia, as well as to determine fish consumption-based risks for T-Hg ingestion. T-Hg levels were measured by electrothermal atomization and atomic absorption spectroscopy. The overall mean T-Hg level in hair for humans in the mining district of San Martin de Loba was 2.12 μg/g, whereas for the reference site, Chimichagua, Cesar, it was 0.58 μg/g. Mean T-Hg levels were not different when considered within localities belonging to the mining district but differed when the comparison included Chimichagua. T-Hg levels in examined locations were weakly but significantly associated with age and height, as well as with fish consumption, except in San Martin de Loba. High T-Hg concentrations in fish were detected in Pseudoplatystoma magdaleniatum, Caquetaia kraussii, Ageneiosus pardalis, Cyrtocharax magdalenae, and Triportheus magdalenae, whereas the lowest appeared in Prochilodus magdalenae and Hemiancistrus wilsoni. In terms of Hg exposure due to fish consumption, only these last two species offer some guarantee of low risk for Hg-related health problems. Water, floating macrophytes, and sediments from effluents near mining sites also had high Hg values. In mines of San Martin de Loba and Hatillo de Loba, for instance, the geoaccumulation index (I(geo)) for sediments reached values greater than 6, indicating extreme pollution. In short, these data support the presence of a high Hg-polluted environment in this mining district, with direct risk for deleterious effects on the health of the mining communities.

Sequential determination of lead and cobalt in tap water and foods samples by fluorescence.

PubMed

Talio, María Carolina; Alesso, Magdalena; Acosta, María Gimena; Acosta, Mariano; Fernández, Liliana P

2014-09-01

In this work, a new procedure was developed for the separation and preconcentration of lead(II) and cobalt(II) in several water and foods samples. Complexes of metal ions with 8-hydroxyquinolein (8-HQ) were formed in aqueous solution. The proposed methodology is based on the preconcentration/separation of Pb(II) by solid-phase extraction using paper filter, followed by spectrofluorimetric determination of both metals, on the solid support and the filtered aqueous solution, respectively. The solid surface fluorescence determination was carried out at λem=455 nm (λex=385 nm) for Pb(II)-8-HQ complex and the fluorescence of Co(II)-8-HQ was determined in aqueous solution using λem=355 nm (λex=225 nm). The calibration graphs are linear in the range 0.14-8.03×10(4) μg L(-1) and 7.3×10(-2)-4.12×10(3) μg L(-1), for Pb(II) and Co(II), respectively, with a detection limit of 4.3×10(-2) and 2.19×10(-2) μg L(-1) (S/N=3). The developed methodology showed good sensitivity and adequate selectivity and it was successfully applied to the determination of trace amounts of lead and cobalt in tap waters belonging of different regions of Argentina and foods samples (milk powder, express coffee, cocoa powder) with satisfactory results. The new methodology was validated by electrothermal atomic absorption spectroscopy with adequate agreement. The proposed methodology represents a novel application of fluorescence to Pb(II) and Co(II) quantification with sensitivity and accuracy similar to atomic spectroscopies. Copyright © 2014 Elsevier B.V. All rights reserved.

40 CFR Appendix A to Subpart C of... - Alternative Testing Methods Approved for Analyses Under the Safe Drinking Water Act

Code of Federal Regulations, 2012 CFR

2012-07-01

... coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2. 2 Arsenic Atomic Absorption... inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2. 2 Barium Inductively Coupled Plasma 3120 B Atomic Absorption; Direct 3111 D Atomic Absorption; Furnace 3113 B 3113 B-04 Axially...

40 CFR Appendix A to Subpart C of... - Alternative Testing Methods Approved for Analyses Under the Safe Drinking Water Act

Code of Federal Regulations, 2011 CFR

2011-07-01

... coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2. 2 Arsenic Atomic Absorption... inductively coupled plasma-atomic emission spectrometry (AVICP-AES) 200.5, Revision 4.2. 2 Barium Inductively Coupled Plasma 3120 B Atomic Absorption; Direct 3111 D Atomic Absorption; Furnace 3113 B 3113 B-04 Axially...

Experimental study of plume induced by nanosecond repetitively pulsed spark microdischarges in air at atmospheric pressure

NASA Astrophysics Data System (ADS)

Orriere, Thomas; Benard, Nicolas; Moreau, Eric; Pai, David

2016-09-01

Nanosecond repetitively pulsed (NRP) spark discharges have been widely studied due to their high chemical reactivity, low gas temperature, and high ionization efficiency. They are useful in many research areas: nanomaterials synthesis, combustion, and aerodynamic flow control. In all of these fields, particular attention has been devoted to chemical species transport and/or hydrodynamic and thermal effects for applications. The aim of this study is to generate an electro-thermal plume by combining an NRP spark microdischarge in a pin-to-pin configuration with a third DC-biased electrode placed a few centimeters away. First, electrical characterization and optical emission spectroscopy were performed to reveal important plasma processes. Second, particle image velocimetry was combined with schlieren photography to investigate the main characteristics of the generated flow. Heating processes are measured by using the N2(C ->B) (0,2) and (1,3) vibrational bands, and effects due to the confinement of the discharge are described. Moreover, the presence of atomic ions N+ and O+ is discussed. Finally, the electro-thermal plume structure is characterized by a flow velocity around 1.8 m.s-1, and the thermal kernel has a spheroidal shape.

Simultaneous Atomic Absorption Spectrometry for Cadmium and Lead Determination in Wastewater: A Laboratory Exercise

ERIC Educational Resources Information Center

Correia, Paulo R. M.; Oliveira, Pedro V.

2004-01-01

The simultaneous determination of cadmium and lead by multi-element atomic absorption spectrometry with electrochemical atomization is proposed by employing a problem-based approach. The reports indicate that the students assimilated the principles of the simultaneous atomic absorption spectrometry (SIMAAS), the role of the chemical modifier, the…

The electrothermal conductance and heat capacity of black phosphorus

NASA Astrophysics Data System (ADS)

Sengupta, Parijat; Das, Saptarshi; Shi, Junxia

2018-03-01

We study a thermal gradient induced current (It h ) flow in potassium-doped two-dimensional anisotropic black phosphorus (BP) with semi-Dirac dispersion. The prototype device is a BP channel clamped between two contacts maintained at unequal temperatures. The choice of BP lies in the predicted efficient thermoelectric behaviour. A temperature-induced difference in the Fermi levels of the two contacts drives the current (typified by the electro-thermal conductance) which we calculate using the Landauer transport equation. The current shows an initial rise when the device is operated at lower temperatures. The rise stalls at progressively higher temperatures and Ith acquires a plateau-like flat profile indicating a competing effect between a larger number of transmission modes and a corresponding drop in the Fermi level difference between the contacts. The current is computed for both n- and p-type BP, and the difference thereof is attributed to the particle-hole asymmetry. The utility of such calculations lie in conversion of the heat produced in a miniaturized chip to useful thermopower via a prototypical Seebeck power generator. Unlike the flow of Ith that purportedly utilizes the additional removable heat in a nanoscale device heat, the ability of a material to maintain a steady temperature is reflected in its heat capacity through effective absorption of thermal energy. The heat capacity is formulated in this work for BP via a Sommerfeld expansion. In the concluding part, we draw a microscopic connection between the two seemingly disparate processes of heat removal and absorption by pinning down their origin to the underlying density of states. Finally, a qualitative analysis of a Carnot-like efficiency of the considered thermoelectric engine is performed drawing upon the previous results on thermal current and heat capacity.

The electrothermal conductance and heat capacity of black phosphorus.

PubMed

Sengupta, Parijat; Das, Saptarshi; Shi, Junxia

2018-03-14

We study a thermal gradient induced current I th flow in potassium-doped two-dimensional anisotropic black phosphorus (BP) with semi-Dirac dispersion. The prototype device is a BP channel clamped between two contacts maintained at unequal temperatures. The choice of BP lies in the predicted efficient thermoelectric behaviour. A temperature-induced difference in the Fermi levels of the two contacts drives the current (typified by the electro-thermal conductance) which we calculate using the Landauer transport equation. The current shows an initial rise when the device is operated at lower temperatures. The rise stalls at progressively higher temperatures and I th acquires a plateau-like flat profile indicating a competing effect between a larger number of transmission modes and a corresponding drop in the Fermi level difference between the contacts. The current is computed for both n- and p-type BP, and the difference thereof is attributed to the particle-hole asymmetry. The utility of such calculations lie in conversion of the heat produced in a miniaturized chip to useful thermopower via a prototypical Seebeck power generator. Unlike the flow of I th that purportedly utilizes the additional removable heat in a nanoscale device heat, the ability of a material to maintain a steady temperature is reflected in its heat capacity through effective absorption of thermal energy. The heat capacity is formulated in this work for BP via a Sommerfeld expansion. In the concluding part, we draw a microscopic connection between the two seemingly disparate processes of heat removal and absorption by pinning down their origin to the underlying density of states. Finally, a qualitative analysis of a Carnot-like efficiency of the considered thermoelectric engine is performed drawing upon the previous results on thermal current and heat capacity.

Problems in determination of skeletal lead burden in archaeological samples: An example from the First African Baptist Church population

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whittmers Jr., L. E.; Aufderheide, A. C.; Pounds, Joel G.

2008-08-01

Human bone lead content has been demonstrated to be related to socioeconomic status, occupation and other social and environmental correlates. Skeletal tissue samples from 135 individuals from an early nineteenth century Philadelphia cemetery (First African Baptist Church) were studied by electrothermal atomic absorption spectrometry and x-ray fluorescence for lead content. High bone lead levels led to investigation of possible diagenetic effects. These were investigated by several different approaches including distribution of lead within bone by x-ray fluorescence, histological preservation, soil lead concentration and acidity as well as location and depth of burial. Bone lead levels were very high in themore » children, exceeding those of the adult population that were buried in the cemetery, and also those of present day adults. The antemortem age-related increase in bone lead, reported in other studies, was not evidenced in this population. Lead was even deposited in areas of taphonomic bone destruction. Synchrotron x-ray fluorescence studies revealed no consistent pattern of lead microdistribution within the bone. Our conclusions are that postmortem diagenesis of lead ion has penetrated these archaeological bones to a degree that makes their original bone lead content irretrievable by any known method. Increased bone porosity is most likely responsible for the very high levels of lead found in bones of newborns and children.« less

Problems in Determination of Skeletal Lead Burden in Archaeological Samples: An Example From the First African Baptist Church Population

DOE Office of Scientific and Technical Information (OSTI.GOV)

Whittmers Jr., L. E.; Aufderheide, A. C.; Pounds, Joel G.

2008-08-01

ABSTRACT Human bone lead content has been demonstrated to be related to socioeconomic status, occupation and other social and environmental correlates. Skeletal tissue samples from 135 individuals from an early nineteenth century Philadelphia cemetery (First African Baptist Church) were studied by electrothermal atomic absorption spectrometry and x-ray fluorescence for lead content. High bone lead levels led to investigation of possible diagenetic effects. These were investigated by several different approaches including distribution of lead within bone by x-ray fluorescence, histological preservation, soil lead concentration and acidity as well as location and depth of burial. Bone lead levels were very high inmore » children, exceeding those of the adult population that were buried in the cemetery, and also those of present day adults. The antemortem age-related increase in bone lead, reported in other studies, was not evidenced in this population. Lead was even deposited in areas of taphonomic bone destruction. Synchrotron x-ray fluorescence studies revealed no consistent pattern of lead microdistribution within the bone. Our conclusions are that postmortem diagenesis of lead ion has penetrated these archaeological bones to a degree that makes their original bone lead content irretrievable by any known method. Increased bone porosity is most likely responsible for the very high levels of lead found in bones of newborns and children.« less

A reflectance flow-through thionine sol-gel sensor for the determination of Se(IV).

PubMed

Carvalhido, Joana A E; Almeida, Agostinho A; Araújo, Alberto N; Montenegro, Maria C B S M

2010-01-01

In this work, a reversible sensor to assess the total Se(IV) content in samples is described. Pre-activated glass slides were spin-coated with 100 microL of a 20-h aged sol-gel mixture of 1 mL of tetramethoxysilane, 305 microL of 50 mmol L(-1) HCl and 2.0 mg of thionine. The flow-cell consisted of one of those slides as a window, and was filled with beads of a polystyrene anionic exchange resin to retain Se(IV) in the form of selenite ions. A reflectance transduction scheme at a wavelength of 596 nm was adopted. The cell was coupled to a multicommutation flow system where a programmed volume of a sample solution and 373 microL of 0.4 mmol L(-1) iodide in a 1.6 mol L(-1) HCl solution were sequentially inserted into the cell. The iodine produced from the reaction of retained Se(IV) with iodide bleached the blue color of thionine. Considering a sample volume of 2.30 mL, with which the preconcentration step was minimized, a linear dynamic working range between 1.5 to 20 microg mL(-1) and a detection limit of 0.29 microg mL(-1) were obtained. The sensor enabled us to perform approximately 200 assays, and provided results similar to those of electrothermal atomic absorption spectrometry.

Arsenic in coal of the Thar coalfield, Pakistan, and its behavior during combustion.

PubMed

Ali, Jamshed; Kazi, Tasneem G; Baig, Jameel A; Afridi, Hassan I; Arain, Mariam S; Brahman, Kapil D; Naeemullah; Panhwar, Abdul H

2015-06-01

The aim of the current study is to evaluate the occurrence of arsenic in coal collected from Thar coalfield, Pakistan, and its behavior during the combustion. Fractionation of arsenic (As) in coal samples was carried out by Community Bureau of Reference sequential extraction scheme (BCR-SES) and single-step-based BCR method (BCR-SS). These methods are validated using the certified reference material of sediment BCR 701 and standard addition method. The stepwise fractions of As in laboratory-made ash (LMA) have been also investigated. The extractable As content associated with different phases in coal and LMA samples were analyzed by electrothermal atomic absorption spectrophotometer. The extraction efficiency of As by BCR-SS was slightly higher than BCR-SES, while the difference was not significant (p < 0.05). The BCR-SS method is a time-saving method because it can reduce the extraction time from 51 to 22 h. The As contents in LMA revealed that during combustion of the coal, >85 % of As may be released into atmosphere. The relative mobility of As in the coal samples was found in increasing order as follows: oxidizable fraction < reducible fraction < acid soluble fraction. The total and extractable As obtained by BCR-SES and BCR-SS were higher in coal samples of block III as compared to block V (p > 0.05).

Flameless atomic-absorption determination of gold in geological materials

USGS Publications Warehouse

Meier, A.L.

1980-01-01

Gold in geologic material is dissolved using a solution of hydrobromic acid and bromine, extracted with methyl isobutyl ketone, and determined using an atomic-absorption spectrophotometer equipped with a graphite furnace atomizer. A comparison of results obtained by this flameless atomic-absorption method on U.S. Geological Survey reference rocks and geochemical samples with reported values and with results obtained by flame atomic-absorption shows that reasonable accuracy is achieved with improved precision. The sensitivity, accuracy, and precision of the method allows acquisition of data on the distribution of gold at or below its crustal abundance. ?? 1980.

Flameless Atomic Absorption Spectroscopy: Effects of Nitrates and Sulfates.

DTIC Science & Technology

1980-05-01

ATTACHED DDJ~P 1413 EDITION 01 INO, 6 5 IabSoLEr J UjN!LbAa~ A- i SELU 0 IONOF I tG 651 J Flameless Atomic Absorption Spectroscopy: Effects of Nitrates...analytical techniques, flameless atomic absorption is subject to matrix or interference effects. Upon heating, nitrate and sulfate salts decompose to...Eklund and J.E. Smith, Anal Chem, 51, 1205 (1979) R.H. Eklund and J.A. Holcombe, Anal Chim. Acta, 109, 97 (1979) FLAMELESS ATOMIC ABSORPTION

[Study on lead absorption in pumpkin by atomic absorption spectrophotometry].

PubMed

Li, Zhen-Xia; Sun, Yong-Dong; Chen, Bi-Hua; Li, Xin-Zheng

2008-07-01

A study was carried out on the characteristic of lead absorption in pumpkin via atomic absorption spectrophotometer. The results showed that lead absorption amount in pumpkin increased with time, but the absorption rate decreased with time; And the lead absorption amount reached the peak in pH 7. Lead and cadmium have similar characteristic of absorption in pumpkin.

Preliminary zoning for risk assessment and remediation purposes in Portman Bay.

NASA Astrophysics Data System (ADS)

Pérez-Sirvent, Carmen; Martínez-Sanchez, MJose; Garcia-Lorenzo, MariLuz; Hernandez-Cordoba, Manuel; Molina, Jose; Gonzalez, Eva; Perez-Espinosa, Victor

2014-05-01

Portman bay is a singular point of mining impact in the Mediterranean area. The site is located in the province of Murcia, south-eastern Spain, and was completely inundated with more than 63 million tonnes of mining waste discharged through a huge washing plant. Wastes from mining activities mainly consisted of ore materials (galena, pyrite and sphalerite), phyllosilicates, in addition to siderite, iron oxides and sometimes alteration products such as jarosite, alunite, kaolinite and greenalite. These materials were submitted to a concentration process by floatation with sea water and as a result of the discharge, the whole of the bay was filled up with wastes which also extended into the Mediterranean Sea. In the last years of activity, wastes were even poured alternatively in the sea or over the sediments filling the bay. These actions have produced a very high heterogeneity in the sediments. Although after the end of the discharges it has been possible to reach a certain degree of balance, the sediments, especially those closest to the sea, are subjected to marine dynamics and the effects of rainfall and runoffs. In 2007, a recuperation pilot project was developed and financed by the Spanish Government. In the first step of this project, the complete physical, chemical and mineralogical characterization of sediments, both in surface and at depth was carried out. Twenty surface samples were collected (<1 m) and twelve sediment cores were also collected at the same time. To determine the total trace element content, zinc and iron levels were determined by flame atomic absorption spectrometry, while lead, cadmium and copper levels were determined by electrothermal atomization atomic absorption spectrometry. The arsenic content was measured by atomic fluorescence spectrometry using an automated continuous flow hydride generation spectrometer. The reliability of the results was verified by analyzing standard reference materials. The mineralogical composition was determined using Cu-Kα radiation with an X-ray Diffractometer and appropriate software. Data for metal leached, Acid-volatile sulphide (AVS) and simultaneously extracted metals (SEM) were also obtained. The results allowed two types of materials to be differentiated. The first one with a fine particle size, is related with the direct discharge of wastes and contains jarosite and other minerals resulting of supergenic alteration. The pH is low and both the level of heavy metals and chemical reactivity are high. The second, different material is black sand, a sediment of coarse texture in which stable minerals, phylosilicates, iron oxides and hydroxides, siderite, pyrite and quartz predominate. The pH is close to neutrality and despite a high heavy metals level, the chemical reactivity is low. The data allowed a preliminary zoning of the risk in the area to be established, and this was the starting point to outline the remediation project.

Use of Bioassay test for the environmental evaluation of mining residues and their leachates: the singular case of the Portman Bay (SE, Spain)

NASA Astrophysics Data System (ADS)

Martínez-Sánchez, Maria Jose; García-Lorenzo, Maria Luz; Pérez-Sirvent, Carmen; Molina, Jose; Tudela, Maria Luz; Hernández-Córdoba, Manuel

2010-05-01

The aim of the present study was to evaluate the toxicity of sediments and their pore-water extracts from sites contaminated by mining activities using two assays: bacteria and plants. The acute toxicity in pore-waters was determined using the Microtox® bioassay, which uses the naturally luminescent marine bacterium Vibrio fischeri. Phytotoxicity in soil samples was tested by way of the seed germination and root elongation technique in three plant species, Sorghum saccharatum, Sinapis alba and Lepidium sativum. The aim of applying these assays is to establish a method for evaluating the real risks within a risk analysis process, considering both present and future risks, bearing in mind that the uses to which soil is put (urban, recreational or industrial) may change. In the zone studied, mining activities have led to heavy metal contamination with the risk of runoff and wind dispersion of the contaminated material. For this study, 6 sediment samples were collected from Portman Bay (Murcia, SE Spain). The soil extract was prepared by saturation with distilled water and allowing it to stand for four hours. Then, the soil was subjected to a vacuum pressure to extract the soil solution through filter paper. The Zn and Fe content was determined by flame atomic absorption spectrometry (FAAS). The Pb, Cd and Cu content was determined by electrothermal atomization atomic absorption spectrometry (ETAAS). The As content was analysed by atomic fluorescence spectrometry using an automated continuous flow hydride generation (As-AFS) spectrometer. Total Pb concentration varied from 600 to 2500 ppm, with a mean value of 1200 ppm. The average content of Zn was 5300 ppm. The mean concentration of Cd and Cu was 23 and 59 ppm, respectively. Total As concentrations varied from 180 to 470 ppm, with an average value 280 ppm. Finally, the total Fe content ranged from 37% to 47%, with an average value of 40%. Pore-water samples showed neutral pH values and average electrical conductivity was 8.4 ds m-1. Mean heavy metal content in leachates from Portman Bay was 6.8 ppm for Pb, 0.1 ppm for Zn, 17 ppb for Cd, 5.6 ppb for Cu, 3.7 ppb for As and 0.6 ppm for Fe. The bioassays showed different sensitivities to the target metals. The Vibrio fischeri luminescence inhibition assay showed less sensitivity to the toxicants in the sediments than phytotoxicity assay. According to our results it is highly advisable to complement chemical analyses with environmental toxicity testing to characterise the risks presented by contaminated soils. Finally, these methods satisfy the requirements of environmental toxicology in their reliability, sensitivity, reproducibility, rapidity and low cost.

21 CFR 862.2850 - Atomic absorption spectrophotometer for clinical use.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Atomic absorption spectrophotometer for clinical... HUMAN SERVICES (CONTINUED) MEDICAL DEVICES CLINICAL CHEMISTRY AND CLINICAL TOXICOLOGY DEVICES Clinical Laboratory Instruments § 862.2850 Atomic absorption spectrophotometer for clinical use. (a) Identification...

Midinfrared absorption measured at a lambda/400 resolution with an atomic force microscope.

PubMed

Houel, Julien; Homeyer, Estelle; Sauvage, Sébastien; Boucaud, Philippe; Dazzi, Alexandre; Prazeres, Rui; Ortéga, Jean-Michel

2009-06-22

Midinfrared absorption can be locally measured using a detection combining an atomic force microscope and a pulsed excitation. This is illustrated for the midinfrared bulk GaAs phonon absorption and for the midinfrared absorption of thin SiO(2) microdisks. We show that the signal given by the cantilever oscillation amplitude of the atomic force microscope follows the spectral dependence of the bulk material absorption. The absorption spatial resolution achieved with microdisks is around 50 nanometer for an optical excitation around 22 micrometer wavelength.

Absorption and emission spectra of Li atoms trapped in rare gas matrices

NASA Astrophysics Data System (ADS)

Wright, J. J.; Balling, L. C.

1980-10-01

Pulsed-dye-laser excitation has been used to investigate the optical absorption and emission spectra of Li atoms trapped in Ar, Kr, and Xe matrices at 10 °K. Attempts to stabilize Li atoms in a Ne matrix at 2 °K were unsuccessful. Results for all three rare gases were qualitatively the same. White light absorption scans showed a single absorption with three peaks centered near the free-atom 2s→2p transition wavelength. The intensity of fluorescence produced by dye-laser excitation within this absorption band was measured as a function of emission wavelength. Excitation of the longest- and shortest-wavelength absorption peaks produced identical emission profiles, but no distinct fluorescence signal was detected when the laser was tuned to the central absorption peaks, indicating that the apparent absorption triplet is actually the superposition of a singlet and a doublet absorption originating from two different trapping sites. No additional absorption bands were detected.

Preliminary investigation of high power microwave plasmas for electrothermal thruster use

NASA Technical Reports Server (NTRS)

Power, John L.; Sullivan, Daniel J.

1993-01-01

Results are reported from preliminary tests to evaluate the high power microwave electrothermal thruster (MET) concept, which employs a free-floating plasma discharge maintained by applied CW microwave power to heat a propellant gas flow. Stable plasmas have been created and maintained in helium (He), nitrogen (N2), and hydrogen (H2) as propellants in both the TM(sub 011) and TM(sub 012) modes at discharge pressures from 10 Pa to 69 kPa. Reproducible starting conditions of pressure and power have been documented for all the plasmas. Vortical inflow of the propellant gas was observed to cause the formation of on-axis 'spike' plasmas. The formation and unformation conditions of these plasmas were studied. Operation in the spike plasma condition enables maximum power absorption with minimum wall heating and offers maximum efficiency in heating the propellant gas. In the spike condition, plasmas of the three propellant gases were investigated in an open channel configuration to a maximum applied power level of 11.2 kW (in N2). Microwave power coupling efficiencies of over 90 percent were routinely obtained at absorbed power levels up to 2 kW. Magnetic nozzle effects were investigated with a superconducting solenoid Al magnet applying a high magnetic field to the plasmas in and exiting from the discharge tube.

Stronger multilayer acrylic dielectric elastomer actuators with silicone gel coatings

NASA Astrophysics Data System (ADS)

Lau, Gih-Keong; La, Thanh-Giang; Sheng-Wei Foong, Ervin; Shrestha, Milan

2016-12-01

Multilayer dielectric elastomer actuators (DEA) perform worst off than single-layer DEAs due to higher susceptibility to electro-thermal breakdown. This paper presents a hot-spot model to predict the electro-thermal breakdown field of DEAs and its dependence on thermal insulation. To inhibit the electrothermal breakdown, silicone gel coating was applied as barrier coating to multilayer acrylic DEA. The gel coating helps suppress the electro-thermally induced puncturing of DEA membrane at the hot spot. As a result, the gel-coated DEAs, in either a single layer or a multilayer stack, can produce 30% more isometric stress change as compared to those none-coated. These gel-coated acrylic DEAs show great potential to make stronger artificial muscles.

AC electrothermal technique in microchannels

NASA Astrophysics Data System (ADS)

Salari, Alinaghi; Navi, Maryam; Dalton, Colin

2017-02-01

Electrokinetic techniques have a wide range of applications in droplet, particle, and fluid manipulation systems. In general, they can be categorized into different subgroups including electroosmosis, electrothermal, electrophoresis, dielectrophoresis, etc. The AC electrothermal (ACET) technique has been shown to be very effective in applications which involve high conductivity fluids, such as blood, which are typically used in biomedical applications. In the past few years, the ACET effect has received considerable attention. Unlike AC electroosmosis (ACEO), the ACET effect shows plateaus in force in a wide frequency range. In other words, with electrothermal force, velocity is more steady and predictable at different frequencies, compared to ACEO and dielectrophoresis (DEP). Although electrothermal microflows form as a result of Joule heating in the fluid, due to high conduction of heat to the ambience, the temperature rise in the fluid is not so high as to threaten the nature of the biofluids. The average temperature rise resulting from the ACET effect is below 5 °K. In order to generate high strength AC electric fields, microfabricated electrode arrays are commonly used in microchannels. For pumping applications, it is essential to create asymmetry in the electric field, typically by having asymmetrical electrode pairs. There is no defined border between many electrokinetic techniques, and as such the point where electrothermal processes interferes with other electrokinetic techniques is not clear in the literature. In addition, there have been comprehensive reviews on micropumps, electrokinetics, and their subcategories, but the literature lacks a detailed up-to-date review on electrothermal microdevices. In this paper, a brief review is made specifically on electric fields in ACET devices, in order to provide an insight for the reader about the importance of this aspect of ACET devices and the improvements made to date.

New generation cut-and-seal devices in oral and oropharyngeal cancer resection: clinical and cost-effectiveness study.

PubMed

Tirelli, G; Del Piero, G C; Valentinuz, G; Monte, A; Gatto, A; Rebelli, A; Quatela, E

2018-04-01

To evaluate the clinical efficacy and cost-effectiveness of ultrasonic shears and the electrothermal bipolar vessel sealing system, in comparison to the traditional cold knife and bipolar forceps, in oral and oropharyngeal cancer surgery. Patients who underwent oral or oropharyngeal cancer resection and neck dissection with either ultrasonic shears (n = 36) or electrothermal bipolar vessel sealing (n = 32) were enrolled. Surgical time, intra-operative bleeding, blood drainage, post-operative pain, neck oedema, complications and hospitalisation duration were compared to those of an historical cohort of 36 patients treated using a cold knife and bipolar forceps. Additionally, a cost-effectiveness evaluation was performed. Ultrasonic shears and, in particular, electrothermal bipolar vessel sealing, were advantageous compared to the traditional techniques. The cost of ultrasonic shears and electrothermal bipolar vessel sealing was completely offset by declining time-driven costs for the surgical team and operating theatre. Ultrasonic shears and, in particular, electrothermal bipolar vessel sealing, are more advantageous compared to the traditional techniques, from both a clinical and economic point of view.

Determination of iridium in mafic rocks by atomic absorption

USGS Publications Warehouse

Grimaldi, F.S.; Schnepfe, M.M.

1970-01-01

Iridium is determined in mineralized mafic rocks by atomic absorption after fire-assay concentration into a gold bead. Interelement interferences in the atomic-absorption determination are removed and Ir sensitivity is increased by buffering the solutions with a mixture of copper and sodium sulphates. Substantial amounts of Ag, Al, Au, Bi, Ca, Cd, Co, Cr, Fe, Ho, Hg, K, La, Mg, Mn, Mo, Ni, Pb, Te, Ti, V, Y, Zn and platinum metals can be tolerated in the atomic-absorption determination. The sensitivity and detection limits are 3.2 and 0.25 ppm of Ir, respectively. ?? 1970.

Collisional redistribution of radiation. II - The effects of degeneracy on the equations of motion for the density matrix. III - The equation of motion for the correlation function and the scattered spectrum

NASA Technical Reports Server (NTRS)

Burnett, K.; Cooper, J.

1980-01-01

The effect of correlations between an absorber atom and perturbers in the binary-collision approximation are applied to degenerate atomic systems. A generalized absorption profile which specifies the final state of the atom after an absorption event is related to the total intensities of Rayleigh scattering and fluorescence from the atom. It is suggested that additional dynamical information to that obtainable from ordinary absorption experiments is required in order to describe redistributed atomic radiation. The scattering of monochromatic radiation by a degenerate atom is computed in a binary-collision approximation; an equation of motion is derived for the correlation function which is valid outside the quantum-regression regime. Solutions are given for the weak-field conditions in terms of generalized absorption and emission profiles that depend on the indices of the atomic multipoles.

Preliminary investigation of electrothermal vaporization sample introduction for inductively coupled plasma time-of-flight mass spectrometry.

PubMed

Mahoney, P P; Ray, S J; Li, G; Hieftje, G M

1999-04-01

The coupling of an electrothermal vaporization (ETV) apparatus to an inductively coupled plasma time-of-flight mass spectrometer (ICP-TOFMS) is described. The ability of the ICP-TOFMS to produce complete elemental mass spectra at high repetition rates is experimentally demonstrated. A signal-averaging data acquisition board is employed to rapidly record complete elemental spectra throughout the vaporization stage of the ETV temperature cycle; a solution containing 34 elements is analyzed. The reduction of both molecular and atomic isobaric interferences through the temperature program of the furnace is demonstrated. Isobaric overlaps among the isotopes of cadmium, tin, and indium are resolved by exploiting differences in the vaporization characteristics of the elements. Figures of merit for the system are defined with several different data acquisition schemes capable of operating at the high repetition rate of the TOF instrument. With the use of both ion counting and a boxcar averager, the dynamic range is shown to be linear over a range of at least 6 orders of magnitude. A pair of boxcar averagers are used to measure the isotope ratio for silver with a precision of 1.9% RSD, despite a cycle-to-cycle precision of 19% RSD. Detection limits of 10-80 fg are calculated for seven elements, based upon a 10-microL injection.

A review of research and development on the microwave-plasma electrothermal rocket

NASA Technical Reports Server (NTRS)

Hawley, Martin C.; Asmussen, Jes; Filpus, John W.; Frasch, Lydell L.; Whitehair, Stanley; Morin, T. J.; Chapman, R.

1987-01-01

The microwave-plasma electrothermal rocket (MWPETR) shows promise for spacecraft propulsion and maneuvering, without some of the drawbacks of competitive electric propulsion systems. In the MWPETR, the electric power is first converted to microwave-frequency radiation. In a specially-designed microwave cavity system, the electromagnetic energy of the radiation is transferred to the electrons in a plasma sustained in the working fluid. The resulting high-energy electrons transfer their energy to the atoms and molecules of the working fluid by collisions. The working fluid, thus heated, expands through a nozzle to generate thrust. In the MWPETR, no electrodes are in contact with the working fluid, the energy is transferred into the working fluid by nonthermal mechanisms, and the main requirement for the materials of construction is that the walls of the plasma chamber be insulating and transparent to microwave radiation at operating conditions. In this survey of work on the MWPETR, several experimental configurations are described and compared. Diagnostic methods used in the study are described and compared, including titration, spectroscopy, calorimetry, electric field measurements, gas-dynamic methods, and thrust measurements. Measured and estimated performance efficiencies are reported. Results of computer modeling of the plasma and of the gas flowing from the plasma are summarized.

Determination of Calcium in Cereal with Flame Atomic Absorption Spectroscopy: An Experiment for a Quantitative Methods of Analysis Course

ERIC Educational Resources Information Center

Bazzi, Ali; Kreuz, Bette; Fischer, Jeffrey

2004-01-01

An experiment for determination of calcium in cereal using two-increment standard addition method in conjunction with flame atomic absorption spectroscopy (FAAS) is demonstrated. The experiment is intended to introduce students to the principles of atomic absorption spectroscopy giving them hands on experience using quantitative methods of…

Efficient atom localization via probe absorption in an inverted-Y atomic system

NASA Astrophysics Data System (ADS)

Wu, Jianchun; Wu, Bo; Mao, Jiejian

2018-06-01

The behaviour of atom localization in an inverted-Y atomic system is theoretically investigated. For the atoms interacting with a weak probe field and several orthogonal standing-wave fields, their position information can be obtained by measuring the probe absorption. Compared with the traditional scheme, we couple the probe field to the transition between the middle and top levels. It is found that the probe absorption sensitively depends on the detuning and strength of the relevant light fields. Remarkably, the atom can be localized at a particular position in the standing-wave fields by coupling a microwave field to the transition between the two ground levels.

A Novel Electro-Thermal Laminated Ceramic with Carbon-Based Layer

PubMed Central

Ji, Yi; Huang, Bin; Rao, Pinggen

2017-01-01

A novel electro-thermal laminated ceramic composed of ceramic tile, carbon-based layer, dielectric layer, and foaming ceramic layer was designed and prepared by tape casting. The surface temperature achieved at an applied voltage of 10 V by the laminated ceramics was 40.3 °C when the thickness of carbon-based suspension was 1.0 mm and the adhesive strength between ceramic tile and carbon-based layer was 1.02 ± 0.06 MPa. In addition, the thermal aging results at 100 °C up to 192 h confirmed the high thermal stability and reliability of the electro-thermal laminated ceramics. The development of this laminated ceramic with excellent electro-thermal properties and safety provides a new individual heating device which is highly expected to be widely applied in the field of indoor heat supply. PMID:28773006

A Novel Electro-Thermal Laminated Ceramic with Carbon-Based Layer.

PubMed

Ji, Yi; Huang, Bin; Rao, Pinggen

2017-06-12

A novel electro-thermal laminated ceramic composed of ceramic tile, carbon-based layer, dielectric layer, and foaming ceramic layer was designed and prepared by tape casting. The surface temperature achieved at an applied voltage of 10 V by the laminated ceramics was 40.3 °C when the thickness of carbon-based suspension was 1.0 mm and the adhesive strength between ceramic tile and carbon-based layer was 1.02 ± 0.06 MPa. In addition, the thermal aging results at 100 °C up to 192 h confirmed the high thermal stability and reliability of the electro-thermal laminated ceramics. The development of this laminated ceramic with excellent electro-thermal properties and safety provides a new individual heating device which is highly expected to be widely applied in the field of indoor heat supply.

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR OPERATION, CALIBRATION AND MAINTENANCE OF THE PERKIN-ELMER ZEEMAN/5000 SYSTEM ATOMIC ABSORPTION SPECTROMETER (BCO-L-6.0)

EPA Science Inventory

The purpose of this SOP is to outline the start-up, calibration, operation, and maintenance procedures for the Perkin-Elmer 5000 atomic absorption spectrophotometer (PE 5000 AA), and the Perkin Elmer 5000 Zeeman graphite furnace atomic absorption spectrophotometer (PE 5000Z GFAA)...

Uranium isotopes quantitatively determined by modified method of atomic absorption spectrophotometry

NASA Technical Reports Server (NTRS)

Lee, G. H.

1967-01-01

Hollow-cathode discharge tubes determine the quantities of uranium isotopes in a sample by using atomic absorption spectrophotometry. Dissociation of the uranium atoms allows a large number of ground state atoms to be produced, absorbing the incident radiation that is different for the two major isotopes.

Anions in Electrothermal Supercharging of Proteins with Electrospray Ionization Follow a Reverse Hofmeister Series

PubMed Central

2015-01-01

The effects of different anions on the extent of electrothermal supercharging of proteins from aqueous ammonium and sodium salt solutions were investigated. Sulfate and hydrogen phosphate are the most effective anions at producing high charge state protein ions from buffered aqueous solution, whereas iodide and perchlorate are ineffective with electrothermal supercharging. The propensity for these anions to produce high charge state protein ions follows the following trend: sulfate > hydrogen phosphate > thiocyanate > bicarbonate > chloride > formate ≈ bromide > acetate > iodide > perchlorate. This trend correlates with the reverse Hofmeister series over a wide range of salt concentrations (1 mM to 2 M) and with several physical properties, including solvent surface tension, anion viscosity B-coefficient, and anion surface/bulk partitioning coefficient, all of which are related to the Hofmeister series. The effectiveness of electrothermal supercharging does not depend on bubble formation, either from thermal degradation of the buffer or from coalescence of dissolved gas. These results provide evidence that the effect of different ions in the formation of high charge state ions by electrothermal supercharging is largely a result of Hofmeister effects on protein stability leading to protein unfolding in the heated ESI droplet. PMID:24410546

Novel atomic absorption spectrometric and rapid spectrophotometric methods for the quantitation of paracetamol in saliva: application to pharmacokinetic studies.

PubMed

Issa, M M; Nejem, R M; El-Abadla, N S; Al-Kholy, M; Saleh, Akila A

2008-01-01

A novel atomic absorption spectrometric method and two highly sensitive spectrophotometric methods were developed for the determination of paracetamol. These techniques based on the oxidation of paracetamol by iron (III) (method I); oxidation of p-aminophenol after the hydrolysis of paracetamol (method II). Iron (II) then reacts with potassium ferricyanide to form Prussian blue color with a maximum absorbance at 700 nm. The atomic absorption method was accomplished by extracting the excess iron (III) in method II and aspirates the aqueous layer into air-acetylene flame to measure the absorbance of iron (II) at 302.1 nm. The reactions have been spectrometrically evaluated to attain optimum experimental conditions. Linear responses were exhibited over the ranges 1.0-10, 0.2-2.0 and 0.1-1.0 mug/ml for method I, method II and atomic absorption spectrometric method, respectively. A high sensitivity is recorded for the proposed methods I and II and atomic absorption spectrometric method value indicate: 0.05, 0.022 and 0.012 mug/ml, respectively. The limit of quantitation of paracetamol by method II and atomic absorption spectrometric method were 0.20 and 0.10 mug/ml. Method II and the atomic absorption spectrometric method were applied to demonstrate a pharmacokinetic study by means of salivary samples in normal volunteers who received 1.0 g paracetamol. Intra and inter-day precision did not exceed 6.9%.

Novel Atomic Absorption Spectrometric and Rapid Spectrophotometric Methods for the Quantitation of Paracetamol in Saliva: Application to Pharmacokinetic Studies

PubMed Central

Issa, M. M.; Nejem, R. M.; El-Abadla, N. S.; Al-Kholy, M.; Saleh, Akila. A.

2008-01-01

A novel atomic absorption spectrometric method and two highly sensitive spectrophotometric methods were developed for the determination of paracetamol. These techniques based on the oxidation of paracetamol by iron (III) (method I); oxidation of p-aminophenol after the hydrolysis of paracetamol (method II). Iron (II) then reacts with potassium ferricyanide to form Prussian blue color with a maximum absorbance at 700 nm. The atomic absorption method was accomplished by extracting the excess iron (III) in method II and aspirates the aqueous layer into air-acetylene flame to measure the absorbance of iron (II) at 302.1 nm. The reactions have been spectrometrically evaluated to attain optimum experimental conditions. Linear responses were exhibited over the ranges 1.0-10, 0.2-2.0 and 0.1-1.0 μg/ml for method I, method II and atomic absorption spectrometric method, respectively. A high sensitivity is recorded for the proposed methods I and II and atomic absorption spectrometric method value indicate: 0.05, 0.022 and 0.012 μg/ml, respectively. The limit of quantitation of paracetamol by method II and atomic absorption spectrometric method were 0.20 and 0.10 μg/ml. Method II and the atomic absorption spectrometric method were applied to demonstrate a pharmacokinetic study by means of salivary samples in normal volunteers who received 1.0 g paracetamol. Intra and inter-day precision did not exceed 6.9%. PMID:20046743

Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

NASA Technical Reports Server (NTRS)

Meyer, Scott Andrew

1995-01-01

The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 x 10(exp 17) and 9 x 10(exp 17)/cu cm. The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

NASA Technical Reports Server (NTRS)

Meyer, Scott Andrew

1995-01-01

The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3x10(exp 17) and 9x10(exp 17) cm(exp -3). The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

Vacuum Ultraviolet Absorption Measurements of Atomic Oxygen in a Shock Tube

NASA Technical Reports Server (NTRS)

Meyer, Scott Andrew

1995-01-01

The absorption of vacuum ultraviolet light by atomic oxygen has been measured in the Electric Arc-driven Shock Tube (EAST) Facility at NASA-Ames Research Center. This investigation demonstrates the instrumentation required to determine atomic oxygen concentrations from absorption measurements in impulse facilities. A shock wave dissociates molecular oxygen, producing a high temperature sample of atomic oxygen in the shock tube. A probe beam is generated with a Raman-shifted ArF excimer laser. By suitable tuning of the laser, absorption is measured over a range of wavelengths in the region of the atomic line at 130.49 nm. The line shape function is determined from measurements at atomic oxygen densities of 3 x 10(exp 17) and 9 x 10(exp 17) cm(exp -3). The broadening coefficient for resonance interactions is deduced from this data, and this value is in accord with available theoretical models.

Electrothermally-Actuated Micromirrors with Bimorph Actuators--Bending-Type and Torsion-Type.

PubMed

Tsai, Cheng-Hua; Tsai, Chun-Wei; Chang, Hsu-Tang; Liu, Shih-Hsiang; Tsai, Jui-Che

2015-06-22

Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA). A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved a large angular movement in the micromirrors. Application of an external electric current 0.04 A to the bending-type, restricted-torsion-type, and free-torsion-type mirrors achieved rotation angles of 1.69°, 3.28°, and 3.64°, respectively.

2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. VIEW IN ROOM 111, ATOMIC ABSORPTION BERYLLIUM ANALYSIS LABORATORY. AIR FILTERS AND SWIPES ARE DISSOLVED WITH ACIDS AND THE REMAINING RESIDUES ARE SUSPENDED IN NITRIC ACID SOLUTION. THE SOLUTION IS PROCESSED THROUGH THE ATOMIC ABSORPTION SPECTROPHOTOMETER TO DETECT THE PRESENCE AND LEVELS OF BERYLLIUM. - Rocky Flats Plant, Health Physics Laboratory, On Central Avenue between Third & Fourth Streets, Golden, Jefferson County, CO

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR OPERATION, CALIBRATION, AND MAINTENANCE OF THE PERKIN-ELMER ZEEMAN/5000 SYSTEM ATOMIC ABSORPTION SPECTROPHOTOMETER (BCO-L-6.0)

EPA Science Inventory

The purpose of this SOP is to outline the start-up, calibration, operation, and maintenance procedures for the Perkin-Elmer 5000 atomic absorption spectrophotometer (PE 5000 AA), and the Perkin Elmer 5000 Zeeman graphite furnace atomic absorption spectrophotometer (PE 5000Z GFAA)...

Evaluation of ultrasound-assisted in situ sorbent formation solid-phase extraction method for determination of arsenic in water, food and biological samples.

PubMed

Ezoddin, Maryam; Majidi, Behrooz; Abdi, Khosrou

2015-01-01

A simple and rapid ultrasound-assisted in situ sorbent formation solid-phase extraction (UAISFSPE) coupled with electrothermal atomic absorption spectrometry detection (ET-AAS) was developed for preconcentration and determination of arsenic (As) in various samples. A small amount of cationic surfactant is dissolved in the aqueous sample containing As ions, which were complexed by ammonium pyrrolidinedithiocarbamate After shaking, a little volume of hexafluorophosphate (NaPF6) as an ion-pairing agent was added into the solution by a microsyringe. Due to the interaction between surfactant and ion-pairing agent, solid particles are formed. The alkyl groups of the surfactant in the solid particles strongly interact with the hydrophobic groups of analytes and become bound. Sonication aids the dispersion of the sorbent into the sample solution and mass transfer of the analyte into the sorbent, thus reducing the extraction time. The solid particles are centrifuged, and the sedimented particles can be dissolved in an appropriate solvent to recover the absorbed analyte. After separation, total arsenic (As(III) and As(V)) was determined by ET-AAS. Several experimental parameters were investigated and optimized. A detection limit of 7 ng L(-1) with preconcentration factor of 100 and relative standard deviation for 10 replicate determinations of 0.1 µg L(-1) As(III) were 4.5% achieved. Consequently, the method was applied to the determination of arsenic in certified reference materials, water, food and biological samples with satisfactory results.

Magnetic ionic liquid-based dispersive liquid-liquid microextraction technique for preconcentration and ultra-trace determination of Cd in honey.

PubMed

Fiorentini, Emiliano F; Escudero, Leticia B; Wuilloud, Rodolfo G

2018-04-19

A simple, highly efficient, batch, and centrifuge-less dispersive liquid-liquid microextraction method based on a magnetic ionic liquid (MIL-DLLME) and electrothermal atomic absorption spectrometry (ETAAS) detection was developed for ultra-trace Cd determination in honey. Initially, Cd(II) was chelated with ammonium diethyldithiophosphate (DDTP) at pH 0.5 followed by its extraction with the MIL trihexyl(tetradecyl)phosphonium tetrachloroferrate(III) ([P 6,6,6,14 ]FeCl 4 ) and acetonitrile as dispersant. The MIL phase containing the analyte was separated from the aqueous phase using only a magnet. A back-extraction procedure was applied to recover Cd from the MIL phase using diluted HNO 3 and this solution was directly injected into the graphite furnace of ETAAS instrument. An extraction efficiency of 93% and a sensitivity enhancement factor of 112 were obtained under optimal experimental conditions. The detection limit (LOD) was 0.4 ng L -1 Cd, while the relative standard deviation (RSD) was 3.8% (at 2 μg L -1 Cd and n = 10), calculated from the peak height of absorbance signals. This work reports the first application of the MIL [P 6,6,6,14 ]FeCl 4 along with the DLLME technique for the successful determination of Cd at trace levels in different honey samples. Graphical abstract Preconcentration of ultratraces of Cd in honey using a magnetic ionic liquid and dispersive liquid-liquid microextraction technique.

Temperature-controlled ionic liquid-based ultrasound-assisted microextraction for preconcentration of trace quantity of cadmium and nickel by using organic ligand in artificial saliva extract of smokeless tobacco products

NASA Astrophysics Data System (ADS)

Arain, Sadaf Sadia; Kazi, Tasneem Gul; Arain, Asma Jabeen; Afridi, Hassan Imran; Baig, Jameel Ahmed; Brahman, Kapil Dev; Naeemullah; Arain, Salma Aslam

2015-03-01

A new approach was developed for the preconcentration of cadmium (Cd) and nickel (Ni) in artificial saliva extract of dry snuff (brown and black) products using temperature-controlled ionic liquid-based ultrasound-assisted dispersive liquid-liquid microextraction (TIL-UDLLμE) followed by electrothermal atomic absorption spectrometry (ETAAS). The Cd and Ni were complexed with ammonium pyrrolidinedithiocarbamate (APDC), extracted in ionic liquid drops, 1-butyl-3-methylimidazolium hexafluorophosphate [C4MIM][PF6]. The multivariate strategy was applied to estimate the optimum values of experimental variables influence the % recovery of analytes by TIL-UDLLμE method. At optimum experimental conditions, the limit of detection (3s) were 0.05 and 0.14 μg L-1 while relative standard deviations (% RSD) were 3.97 and 3.55 for Cd and Ni respectively. After extraction, the enhancement factors (EF) were 87 and 79 for Cd and Ni, respectively. The RSD for six replicates of 10 μg L-1 Cd and Ni were 3.97% and 3.55% respectively. To validate the proposed method, certified reference material (CRM) of Virginia tobacco leaves was analyzed, and the determined values of Cd and Ni were in good agreement with the certified values. The concentration of Cd and Ni in artificial saliva extracts corresponds to 39-52% and 21-32%, respectively, of the total contents of both elements in dry brown and black snuff products.

Analytical determination of selenium in medical samples, staple food and dietary supplements by means of total reflection X-ray fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Stosnach, Hagen

2010-09-01

Selenium is essential for many aspects of human health and, thus, the object of intensive medical research. This demands the use of analytical techniques capable of analysing selenium at low concentrations with high accuracy in widespread matrices and sometimes smallest sample amounts. In connection with the increasing importance of selenium, there is a need for rapid and simple on-site (or near-to-site) selenium analysis in food basics like wheat at processing and production sites, as well as for the analysis of this element in dietary supplements. Common analytical techniques like electrothermal atomic absorption spectroscopy (ETAAS) and inductively-coupled plasma mass spectrometry (ICP-MS) are capable of analysing selenium in medical samples with detection limits in the range from 0.02 to 0.7 μg/l. Since in many cases less complicated and expensive analytical techniques are required, TXRF has been tested regarding its suitability for selenium analysis in different medical, food basics and dietary supplement samples applying most simple sample preparation techniques. The reported results indicate that the accurate analysis of selenium in all sample types is possible. The detection limits of TXRF are in the range from 7 to 12 μg/l for medical samples and 0.1 to 0.2 mg/kg for food basics and dietary supplements. Although this sensitivity is low compared to established techniques, it is sufficient for the physiological concentrations of selenium in the investigated samples.

Determination of hexavalent chromium in exhaled breath condensate and environmental air among chrome plating workers.

PubMed

Goldoni, Matteo; Caglieri, Andrea; Poli, Diana; Vettori, Maria Vittoria; Corradi, Massimo; Apostoli, Pietro; Mutti, Antonio

2006-03-15

Chromium speciation has attracted attention because of the different toxicity of Cr(III), which is considered relatively non-toxic, and Cr(VI), which can cross cell membranes mainly as a chromate anion and has been classified as a class I human carcinogen. The aims of the present study were to measure soluble Cr(VI) levels in environmental samples, to develop a simple method of quantifying Cr(VI) in exhaled breath condensate (EBC), and to follow the kinetics of EBC Cr(VI) in chrome plating workers.Personal air samples were collected from 10 chrome platers; EBC was collected from the same workers immediately after the work shift on Tuesday and before the work shift on the following Wednesday. Environmental and EBC Cr(VI) levels were determined by means of colorimetry and electrothermal absorption atomic spectrometry, respectively.The method of detecting Cr(VI) in environmental air was based on the extraction of the Cr(VI)-diphenylcarbazide (Cr(VI)-DPC) complex in 1-butanol, whereas EBC Cr(VI) was determined using a solvent extraction of Cr(VI) as an ion pair with tetrabutylammonium ion, and subsequent direct determination of the complex (Cr(VI)-DPC) in EBC.Kinetic data showed that airborne Cr(VI) was reduced by 50% in airway lining fluid sampled at the end of exposure and that there was a further 50% reduction after about 15 h. The persistence of Cr(VI) in EBC supports the use of EBC in assessing target tissue levels of Cr(VI).

Coupled electro-thermal field in a high current electrolysis cell or liquid metal batteries

PubMed Central

Cai, Liwei; Ni, Haiou; Lu, Gui-Min; Yu, Jian-Guo

2018-01-01

Coupled electro-thermal field exists widely in chemical batteries and electrolysis industry. In this study, a three-dimensional numerical model, which is based on the finite-element software ANSYS, has been built to simulate the electro-thermal field in a magnesium electrolysis cell. The adjustment of the relative position of the anode and cathode can change the energy consumption of the magnesium electrolysis process significantly. Besides, the current intensity has a nonlinear effect on heat balance, and the effects of heat transfer coefficients, electrolysis and air temperature on the heat balance have been released to maintain the thermal stability in a magnesium electrolysis cell. The relationship between structure as well as process parameters and electro-thermal field has been obtained and the simulation results can provide experience for the scale-up design in liquid metal batteries. PMID:29515848

Simulation analysis of rectifying microfluidic mixing with field-effect-tunable electrothermal induced flow.

PubMed

Liu, Weiyu; Ren, Yukun; Tao, Ye; Yao, Bobin; Li, You

2018-03-01

We report herein field-effect control on in-phase electrothermal streaming from a theoretical point of view, a phenomenon termed "alternating-current electrothermal-flow field effect transistor" (ACET-FFET), in the context of a new technology for handing analytes in microfluidics. Field-effect control through a gate terminal endows ACET-FFET the ability to generate arbitrary symmetry breaking in the transverse vortex flow pattern, which makes it attractive for mixing microfluidic samples. A computational model is developed to study the feasibility of this new microfluidic device design for micromixing. The influence of various parameters on developing an efficient mixer is investigated, and an integrated layout of discrete electrode array is suggested for achieving high-throughput mixing. Our physical demonstration with field-effect electrothermal flow control using a simple electrode structure proves invaluable for designing active micromixers for modern micro total analytical system. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Electrothermally actuated tunable clamped-guided resonant microbeams

NASA Astrophysics Data System (ADS)

Alcheikh, N.; Hajjaj, A. Z.; Jaber, N.; Younis, M. I.

2018-01-01

We present simulation and experimental investigation demonstrating active alteration of the resonant and frequency response behavior of resonators by controlling the electrothermal actuation method on their anchors. In-plane clamped-guided arch and straight microbeams resonators are designed and fabricated with V-shaped electrothermal actuators on their anchors. These anchors not only offer various electrothermal actuation options, but also serve as various mechanical stiffness elements that affect the operating resonance frequency of the structures. We have shown that for an arch, the first mode resonance frequency can be increased up to 50% of its initial value. For a straight beam, we have shown that before buckling, the resonance frequency decreases to very low values and after buckling, it increases up to twice of its initial value. These results can be promising for the realization of different wide-range tunable microresonator. The experimental results have been compared to multi-physics finite-element simulations showing good agreement among them.

A review of production methods of carbon nanotube and graphene thin films for electrothermal applications

NASA Astrophysics Data System (ADS)

Janas, D.; Koziol, K. K.

2014-02-01

Electrothermal materials transform electric energy into heat due to the Joule effect. To date, resistive wires made of heavy metal alloys have primarily been used as the heat source in many appliances surrounding us. Recent discoveries in the field of carbon nanostructures revealed that they can offer a spectrum of advantages over the traditional materials. We review the production methods of thin films composed of carbon nanotubes or graphene and depict how they can be used as conductive coatings for electrothermal applications. We screen all reports from the field up to now and highlight the features of designed nanoheaters. A particular focus is placed on the analysis of general findings of how to tune their electrothermal properties, why carbon nanostructure devices operate the way they do and in what aspects they are superior to the currently available materials on the market.

Improving the binding efficiency of quartz crystal microbalance biosensors by applying the electrothermal effect

PubMed Central

Huang, Yao-Hung; Chang, Jeng-Shian; Chao, Sheng D.; Wu, Kuang-Chong; Huang, Long-Sun

2014-01-01

A quartz crystal microbalance (QCM) serving as a biosensor to detect the target biomolecules (analytes) often suffers from the time consuming process, especially in the case of diffusion-limited reaction. In this experimental work, we modify the reaction chamber of a conventional QCM by integrating into the multi-microelectrodes to produce electrothermal vortex flow which can efficiently drive the analytes moving toward the sensor surface, where the analytes were captured by the immobilized ligands. The microelectrodes are placed on the top surface of the chamber opposite to the sensor, which is located on the bottom of the chamber. Besides, the height of reaction chamber is reduced to assure that the suspended analytes in the fluid can be effectively drived to the sensor surface by induced electrothermal vortex flow, and also the sample costs are saved. A series of frequency shift measurements associated with the adding mass due to the specific binding of the analytes in the fluid flow and the immobilized ligands on the QCM sensor surface are performed with or without applying electrothermal effect (ETE). The experimental results show that electrothermal vortex flow does effectively accelerate the specific binding and make the frequency shift measurement more sensible. In addition, the images of the binding surfaces of the sensors with or without applying electrothermal effect are taken through the scanning electron microscopy. By comparing the images, it also clearly indicates that ETE does raise the specific binding of the analytes and ligands and efficiently improves the performance of the QCM sensor. PMID:25538808

Embedded dielectric water "atom" array for broadband microwave absorber based on Mie resonance

NASA Astrophysics Data System (ADS)

Gogoi, Dhruba Jyoti; Bhattacharyya, Nidhi Saxena

2017-11-01

A wide band microwave absorber at X-band frequency range is demonstrated numerically and experimentally by embedding a simple rectangular structured dielectric water "atom" in flexible silicone substrate. The absorption peak of the absorber is tuned by manipulating the size of the dielectric water "atom." The frequency dispersive permittivity property of the water "atom" shows broadband absorption covering the entire X-band above 90% efficiency with varying the size of the water "atom." Mie resonance of the proposed absorber provides the desired impedance matching condition at the air-absorber interface across a wide frequency range in terms of electric and magnetic resonances. Multipole decomposition of induced current densities is used to identify the nature of observed resonances. Numerical absorptivity verifies that the designed absorber is polarization insensitive for normal incidence and can maintain an absorption bandwidth of more than 2 GHz in a wide-angle incidence. Additionally, the tunability of absorption property with temperature is shown experimentally.

Do Atoms Really "Emit" Absorption Lines?

ERIC Educational Resources Information Center

Brecher, Kenneth

1991-01-01

Presents three absorption line sources that enhance student understanding of the phenomena associated with the interaction of light with matter and help dispel the misconception that atoms "emit" absorption lines. Sources include neodymium, food coloring and other common household liquids, and fluorescent materials. (MDH)

Determination of trace and minor elements in alloys by atomic-absorption spectroscopy using an induction-heated graphite-well furnace as atom source-II.

PubMed

Ashy, M A; Headridge, J B; Sowerbutts, A

1974-06-01

Results are presented for the atomic-absorption spectrophotometric determination of zinc in aluminium and aluminium-silicon alloys, and aluminium, antimony and tin in steels, by means of solid samples dropped into an induction-heated graphite-well furnace to produce the atomic vapour.

Electrothermally-Actuated Micromirrors with Bimorph Actuators—Bending-Type and Torsion-Type

PubMed Central

Tsai, Cheng-Hua; Tsai, Chun-Wei; Chang, Hsu-Tang; Liu, Shih-Hsiang; Tsai, Jui-Che

2015-01-01

Three different electrothermally-actuated MEMS micromirrors with Cr/Au-Si bimorph actuators are proposed. The devices are fabricated with the SOIMUMPs process developed by MEMSCAP, Inc. (Durham, NC, USA). A silicon-on-insulator MEMS process has been employed for the fabrication of these micromirrors. Electrothermal actuation has achieved a large angular movement in the micromirrors. Application of an external electric current 0.04 A to the bending-type, restricted-torsion-type, and free-torsion-type mirrors achieved rotation angles of 1.69°, 3.28°, and 3.64°, respectively. PMID:26110409

Determination of urinary manganese by the direct chelation-extraction method and flameless atomic absorption spectrophotometry.

PubMed Central

Watanabe, T; Tokunaga, R; Iwahana, T; Tati, M; Ikeda, M

1978-01-01

The direct chelation-extraction method, originally developed by Hessel (1968) for blood lead analysis, has been successfully applied to urinalysis for manganese. The analyses of 35 urine samples containing up to 100 microgram/1 of manganese from manganese-exposed workers showed that the data obtained by this method agree well with those by wet digestion-flame atomic absorption spectrophotometry and also by flameless atomic absorption spectrophotometry. PMID:629893

[Determination of trace cobalt in human urine by graphite furnace atomic absorption spectrometr].

PubMed

Zhong, L X; Ding, B M; Jiang, D; Liu, D Y; Yu, B; Zhu, B L; Ding, L

2016-05-20

To establish a method to determine cobalt in human urine by graphite furnace atomic absorption spectrometry. Urine with 2% nitric acid diluted two-fold, to quantify the curve, graphite furnace atomic absorption spectrometric detection. Co was linear within 2.5~40.0 ng/ml with r>0.999. Spike experiment showed that Co received good recovery rate, which was 90.8%~94.8%. Intra-assay precisions were 3.2%~5.1% for Co, inter-assay precisions were 4.4%~5.2% for Co. The method by using graphite furnace atomic absorption spectrometr to determine urine Co was fast, accurate and with low matrix effect. It could meet the requirement in GBZ/T 210.5-2008.

Modeling, measuring, and mitigating instability growth in liner implosions on Z

NASA Astrophysics Data System (ADS)

Peterson, Kyle

2015-11-01

Electro-thermal instabilities result from non-uniform heating due to temperature dependence in the conductivity of a material. In this talk, we will discuss the role of electro-thermal instabilities on the dynamics of magnetically accelerated implosion systems. We present simulations that show electro-thermal instabilities form immediately after the surface material of a conductor melts and can act as a significant seed to subsequent magneto-Rayleigh-Taylor (MRT) instability growth. We discuss measurement results from experiments performed on Sandia National Laboratories Z accelerator to investigate signatures of electro-thermal instability growth on well-characterized initially solid aluminum or beryllium rods driven with a 20 MA, 100 ns risetime current pulse. These measurements show good agreement with electro-thermal instability simulations and exhibit larger instability growth than can be explained by MRT theory alone. Recent experiments have confirmed simulation predictions of dramatically reduced instability growth in solid metallic rods when thick dielectric coatings are used to mitigate density perturbations arising from the electro-thermal instability. These results provide further evidence that the inherent surface roughness of the target is not the dominant seed for the MRT instability, in contrast with most inertial confinement fusion approaches. These results suggest a new technique for substantially reducing the integral MRT growth in magnetically driven implosions. Indeed, recent results on the Z facility with 100 km/s Al and Be liner implosions show substantially reduced growth. These new results include axially magnetized, CH-coated beryllium liner radiographs in which the inner liner surface is observed to be remarkably straight and uniform at a radius of about 120 microns (convergence ratio ~20). Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under contract DE-AC04-94AL85000.

Comparison of two methods for blood lead analysis in cattle: graphite-furnace atomic absorption spectrometry and LeadCare(R) II system.

PubMed

Bischoff, Karyn; Gaskill, Cynthia; Erb, Hollis N; Ebel, Joseph G; Hillebrandt, Joseph

2010-09-01

The current study compared the LeadCare(R) II test kit system with graphite-furnace atomic absorption spectrometry for blood lead (Pb) analysis in 56 cattle accidentally exposed to Pb in the field. Blood Pb concentrations were determined by LeadCare II within 4 hr of collection and after 72 hr of refrigeration. Blood Pb concentrations were determined by atomic absorption spectrometry, and samples that were coagulated (n = 12) were homogenized before analysis. There was strong rank correlation (R(2) = 0.96) between atomic absorption and LeadCare II (within 4 hr of collection), and a conversion formula was determined for values within the observed range (3-91 mcg/dl, although few had values >40 mcg/dl). Median and mean blood pb concentrations for atomic absorption were 7.7 and 15.9 mcg/dl, respectively; for LeadCare II, medians were 5.2 mcg/dl at 4 hr and 4.9 mcg/dl at 72 hr, and means were 12.4 and 11.7, respectively. LeadCare II results at 4 hr strongly correlated with 72 hr results (R(2) = 0.96), but results at 72 hr were lower (P < 0.01). There was no significant difference between coagulated and uncoagulated samples run by atomic absorption. Although there have been several articles that compared LeadCare with other analytical techniques, all were for the original system, not LeadCare II. The present study indicated that LeadCare II results correlated well with atomic absorption over a wide range of blood Pb concentrations and that refrigerating samples for up to 72 hr before LeadCare II analysis was acceptable for clinical purposes.

A non-resonant fiber scanner based on an electrothermally-actuated MEMS stage

PubMed Central

Zhang, Xiaoyang; Duan, Can; Liu, Lin; Li, Xingde; Xie, Huikai

2015-01-01

Scanning fiber tips provides the most convenient way for forward-viewing fiber-optic microendoscopy. In this paper, a distal fiber scanning method based on a large-displacement MEMS actuator is presented. A single-mode fiber is glued on the micro-platform of an electrothermal MEMS stage to realize large range non-resonantscanning. The micro-platform has a large piston scan range of up to 800 µm at only 6V. The tip deflection of the fiber can be further amplified by placing the MEMS stage at a proper location along the fiber. A quasi-static model of the fiber-MEMS assembly has been developed and validated experimentally. The frequency response has also been studied and measured. A fiber tip deflection of up to 1650 µm for the 45 mm-long movable fiber portion has been achieved when the MEMS electrothermal stage was placed 25 mm away from the free end. The electrothermally-actuated MEMS stage shows a great potential for forward viewing fiber scanning and optical applications. PMID:26347583

Identification of B-K near edge x-ray absorption fine structure peaks of boron nitride thin films prepared by sputtering deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niibe, Masahito; Miyamoto, Kazuyoshi; Mitamura, Tohru

2010-09-15

Four {pi}{sup *} resonance peaks were observed in the B-K near edge x-ray absorption fine structure spectra of boron nitride thin films prepared by magnetron sputtering. In the past, these peaks have been explained as the K-absorption of boron atoms, which are present in environment containing nitrogen vacancies, the number of which is 1-3 corresponding to the three peaks at higher photon energy. However, the authors found that there was a strong correlation between the intensities of these three peaks and that of O-K absorption after wide range scanning and simultaneous measurement of nitrogen and oxygen K-absorptions of the BNmore » films. Therefore, the authors conclude that these three peaks at the higher energy side correspond to boron atoms bound to one-to-three oxygen atoms instead of three nitrogen atoms surrounding the boron atom in the h-BN structure. The result of the first-principles calculation with a simple cluster model supported the validity of this explanation.« less

Visualizing the Solute Vaporization Interference in Flame Atomic Absorption Spectroscopy

ERIC Educational Resources Information Center

Dockery, Christopher R.; Blew, Michael J.; Goode, Scott R.

2008-01-01

Every day, tens of thousands of chemists use analytical atomic spectroscopy in their work, often without knowledge of possible interferences. We present a unique approach to study these interferences by using modern response surface methods to visualize an interference in which aluminum depresses the calcium atomic absorption signal. Calcium…

Speciation analysis of arsenic in biological matrices by automated hydride generation-cryotrapping-atomic absorption spectrometry with multiple microflame quartz tube atomizer (multiatomizer).

EPA Science Inventory

This paper describes an automated system for the oxidation state specific speciation of inorganic and methylated arsenicals by selective hydride generation - cryotrapping- gas chromatography - atomic absorption spectrometry with the multiatomizer. The corresponding arsines are ge...

[Determination of metal elements in Achyranthis bidentatae radix from various habitats].

PubMed

Tu, Wan-Qian; Zhang, Liu-Ji

2011-12-01

To establish an atomic absorption spectrometry method for determination of the contents of metal elements in Achyranthis Bidentatae Radix and analyze 21 batches of samples from different areas. Fe, Mn, Ca, Mg, K, Zn and Cu were detected by atomic absorption spectrometry with hydrogen flame detector, Pb, As and Cd were detected by graphite furnace atomic absorption, Hg was detected by cold atomic absorption. The heavy metal contents met the requirement of Chinese Pharmacopoeia. The contents of K, Mg, Cu and Mn in the samples of geo-authentic areas were higher,while the contents of Fe, Zn, Hg and Pb in the samples of non-authentic areas were higher. This method is sample, accurate, repeatable and could be used to evaluate the quality of Achyranthis Bidentatae Radix.

Study of monopropellants for electrothermal thrusters: Analytical task summary report

NASA Technical Reports Server (NTRS)

Kuenzly, J. D.; Grabbi, R.

1973-01-01

The feasibility of operating small thrust level electrothermal thrusters is determined with monopropellants other than MIL-grade hydrazine. The work scope includes analytical study, design and fabrication of demonstration thrusters, and an evaluation test program where monopropellants with freezing points lower than MIL-grade hydrazine are evaluated and characterized to determine their applicability to electrothermal thrusters for spacecraft attitude control. Results of propellant chemistry studies and performance analyses indicated that the most promising candidate monopropellants to be investigated are monomethylhydrazine, Aerozine-50, 77% hydrazine-23% hydrazine azide blend, and TRW formulated mixed hydrazine monopropellant (MHM) consisting of 35% hydrazine-50% monomethylhydrazine-15% ammonia.

The Free-Free Absorption Coefficients of the Negative Helium Ion

NASA Astrophysics Data System (ADS)

John, T. L.

1994-08-01

Free-free absorption coefficients of the negative helium ion are calculated by a phaseshift approximation, using continuum data that accurately account for electron-atom correlation and polarization. The approximation is considered to yield results within a few per cent of numerical values for wavelengths greater than 1 m, over the temperature range 1400-10080 K. These coefficients are expected to give the best current estimates of He - continuous absorption. Key words: atomic data - atomic processes - stars: atmospheres - infrared: general.

Absorption of infrared radiation by electrons in the field of a neutral hydrogen atom

NASA Technical Reports Server (NTRS)

Stallcop, J. R.

1974-01-01

An analytical expression for the absorption coefficient is developed from a relationship between the cross-section for inverse bremsstrahlung absorption and the cross-section for electron-atom momentum transfer; it is accurate for those photon frequencies v and temperatures such that hv/kT is small. The determination of the absorption of infrared radiation by free-free transitions of the negative hydrogen ion has been extended to higher temperatures. A simple analytical expression for the absorption coefficient has been derived.

Three-dimensional atom localization via electromagnetically induced transparency in a three-level atomic system.

PubMed

Wang, Zhiping; Cao, Dewei; Yu, Benli

2016-05-01

We present a new scheme for three-dimensional (3D) atom localization in a three-level atomic system via measuring the absorption of a weak probe field. Owing to the space-dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the probe absorption. It is found that, by properly varying the parameters of the system, the probability of finding the atom in 3D space can be almost 100%. Our scheme opens a promising way to achieve high-precision and high-efficiency 3D atom localization, which provides some potential applications in laser cooling or atom nano-lithography via atom localization.

Micro determination of plasma and erythrocyte copper by atomic absorption spectrophotometry

PubMed Central

Blomfield, Jeanette; Macmahon, R. A.

1969-01-01

The free and total plasma copper and total erythrocyte copper levels have been determined by simple, yet sensitive and highly specific methods, using atomic absorption spectrophotometry. For total copper determination, the copper was split from its protein combination in plasma or red cells by the action of hydrochloric acid at room temperature. The liberated copper was chelated by ammonium pyrrolidine dithiocarbamate and extracted into n-butyl acetate by shaking and the organic extract was aspirated into the atomic absorption spectrophotometer flame. The entire procedure was carried out in polypropylene centrifuge tubes, capped during shaking. For the free plasma copper measurement the hydrochloric acid step was omitted. Removal of the plasma or erythrocyte proteins was found to be unnecessary, and, in addition, the presence of trichloracetic acid caused an appreciable lowering of absorption. Using a double-beam atomic absorption spectrophotometer and scale expansion × 10, micro methods have been derived for determining the total copper of plasma or erythrocytes with 0·1 ml of sample, and the free copper of plasma with 0·5 ml. The macro plasma copper method requires 2 ml of plasma and is suitable for use with single-beam atomic absorption spectrophotometers. With blood from 50 blood donors, normal ranges of plasma and erythrocyte copper have been determined. PMID:5776543

Ultraviolet absorption experiment MA-059

NASA Technical Reports Server (NTRS)

Donahue, T. M.; Hudson, R. D.; Anderson, J.; Kaufman, F.; Mcelroy, M. B.

1976-01-01

The ultraviolet absorption experiment performed during the Apollo Soyuz mission involved sending a beam of atomic oxygen and atomic nitrogen resonance radiation, strong unabsorbable oxygen and nitrogen radiation, and visual radiation, all filling the same 3 deg-wide field of view from the Apollo to the Soyuz. The radiation struck a retroreflector array on the Soyuz and was returned to a spectrometer onboard the Apollo. The density of atomic oxygen and atomic nitrogen between the two spacecraft was measured by observing the amount of resonance radiation absorbed when the line joining Apollo and Soyuz was perpendicular to their velocity with respect to the ambient atmosphere. Information concerning oxygen densities was also obtained by observation of resonantly fluorescent light. The absorption experiments for atomic oxygen and atomic nitrogen were successfully performed at a range of 500 meters, and abundant resonance fluorescence data were obtained.

Determination of Copper by Graphite Furnace Atomic Absorption Spectrophotometry: A Student Exercise in Instrumental Methods of Analysis.

ERIC Educational Resources Information Center

Williamson, Mark A.

1989-01-01

Discusses a student exercise which requires the optimizing of the charring and atomization temperatures by producing a plot of absorbance versus temperature for each temperature parameter. Notes that although the graphite furnace atomic absorption spectroscopy technique has widespread industrial use, there are no published, structured experiments…

Photon absorption potential coefficient as a tool for materials engineering

NASA Astrophysics Data System (ADS)

Akande, Raphael Oluwole; Oyewande, Emmanuel Oluwole

2016-09-01

Different atoms achieve ionizations at different energies. Therefore, atoms are characterized by different responses to photon absorption in this study. That means there exists a coefficient for their potential for photon absorption from a photon source. In this study, we consider the manner in which molecular constituents (atoms) absorb photon from a photon source. We observe that there seems to be a common pattern of variation in the absorption of photon among the electrons in all atoms on the periodic table. We assume that the electrons closest to the nucleus (En) and the electrons closest to the outside of the atom (Eo) do not have as much potential for photon absorption as the electrons at the middle of the atom (Em). The explanation we give to this effect is that the En electrons are embedded within the nuclear influence, and similarly, Eo electrons are embedded within the influence of energies outside the atom that there exists a low potential for photon absorption for them. Unlike En and Eo, Em electrons are conditioned, such that there is a quest for balance between being influenced either by the nuclear force or forces external to the atom. Therefore, there exists a higher potential for photon absorption for Em electrons than for En and Eo electrons. The results of our derivations and analysis always produce a bell-shaped curve, instead of an increasing curve as in the ionization energies, for all elements in the periodic table. We obtained a huge data of PAPC for each of the several materials considered. The point at which two or more PAPC values cross one another is termed to be a region of conflicting order of ionization, where all the atoms absorb equal portion of the photon source at the same time. At this point, a greater fraction of the photon source is pumped into the material which could lead to an explosive response from the material. In fact, an unimaginable and unreported phenomenon (in physics) could occur, when two or more PAPCs cross, and the material is able to absorb more than that the photon source could provide, at this point. These resulting effects might be of immense materials engineering applications.

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicatemore » the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. Finally, an intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.« less

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

NASA Astrophysics Data System (ADS)

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; Leone, Stephen R.

2016-01-01

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicate the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. An intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.

Attosecond transient absorption of argon atoms in the vacuum ultraviolet region: line energy shifts versus coherent population transfer

DOE PAGES

Cao, Wei; Warrick, Erika R.; Neumark, Daniel M.; ...

2016-01-18

Using attosecond transient absorption, the dipole response of an argon atom in the vacuum ultraviolet (VUV) region is studied when an external electromagnetic field is present. An isolated attosecond VUV pulse populates Rydberg states lying 15 eV above the argon ground state. A synchronized few-cycle near infrared (NIR) pulse modifies the oscillating dipoles of argon impulsively, leading to alterations in the VUV absorption spectra. As the NIR pulse is delayed with respect to the VUV pulse, multiple features in the absorption profile emerge simultaneously including line broadening, sideband structure, sub-cycle fast modulations, and 5-10 fs slow modulations. These features indicatemore » the coexistence of two general processes of the light-matter interaction: the energy shift of individual atomic levels and coherent population transfer between atomic eigenstates, revealing coherent superpositions. Finally, an intuitive formula is derived to treat both effects in a unifying framework, allowing one to identify and quantify the two processes in a single absorption spectrogram.« less

Diode Lasers and Practical Trace Analysis.

ERIC Educational Resources Information Center

Imasaka, Totaro; Nobuhiko, Ishibashi

1990-01-01

Applications of lasers to molecular absorption spectrometry, molecular fluorescence spectrometry, visible semiconductor fluorometry, atomic absorption spectrometry, and atomic fluorescence spectrometry are discussed. Details of the use of the frequency-doubled diode laser are provided. (CW)

Modeling the Oxygen K Absorption in the Interstellar Medium: An XMM-Newton View of Sco X-1

NASA Technical Reports Server (NTRS)

Garcia, J.; Ramirez, J. M.; Kallman, T. R.; Witthoeft, M.; Bautista, M. A.; Mendoza, C.; Palmeri, P.; Quinet, P.

2011-01-01

We investigate the absorption structure of the oxygen in the interstellar medium by analyzing XMM-Newton observations of the low mass X-ray binary Sco X-1. We use simple models based on the O I atomic cross section from different sources to fit the data and evaluate the impact of the atomic data in the interpretation of astrophysical observations. We show that relatively small differences in the atomic calculations can yield spurious results. We also show that the most complete and accurate set of atomic cross sections successfully reproduce the observed data in the 21 - 24.5 Angstrom wavelength region of the spectrum. Our fits indicate that the absorption is mainly due to neutral gas with an ionization parameter of Epsilon = 10(exp -4) erg/sq cm, and an oxygen column density of N(sub O) approx. = 8-10 x 10(exp 17)/sq cm. Our models are able to reproduce both the K edge and the K(alpha) absorption line from O I, which are the two main features in this region. We find no conclusive evidence for absorption by other than atomic oxygen.

A flow-batch analyzer with piston propulsion applied to automatic preparation of calibration solutions for Mn determination in mineral waters by ET AAS.

PubMed

Almeida, Luciano F; Vale, Maria G R; Dessuy, Morgana B; Silva, Márcia M; Lima, Renato S; Santos, Vagner B; Diniz, Paulo H D; Araújo, Mário C U

2007-10-31

The increasing development of miniaturized flow systems and the continuous monitoring of chemical processes require dramatically simplified and cheap flow schemes and instrumentation with large potential for miniaturization and consequent portability. For these purposes, the development of systems based on flow and batch technologies may be a good alternative. Flow-batch analyzers (FBA) have been successfully applied to implement analytical procedures, such as: titrations, sample pre-treatment, analyte addition and screening analysis. In spite of its favourable characteristics, the previously proposed FBA uses peristaltic pumps to propel the fluids and this kind of propulsion presents high cost and large dimension, making unfeasible its miniaturization and portability. To overcome these drawbacks, a low cost, robust, compact and non-propelled by peristaltic pump FBA is proposed. It makes use of a lab-made piston coupled to a mixing chamber and a step motor controlled by a microcomputer. The piston-propelled FBA (PFBA) was applied for automatic preparation of calibration solutions for manganese determination in mineral waters by electrothermal atomic-absorption spectrometry (ET AAS). Comparing the results obtained with two sets of calibration curves (five by manual and five by PFBA preparations), no significant statistical differences at a 95% confidence level were observed by applying the paired t-test. The standard deviation of manual and PFBA procedures were always smaller than 0.2 and 0.1mugL(-1), respectively. By using PFBA it was possible to prepare about 80 calibration solutions per hour.

Biochemical and behavioural responses of the endobenthic bivalve Scrobicularia plana to silver nanoparticles in seawater and microalgal food.

PubMed

Buffet, Pierre-Emmanuel; Pan, Jin-Fen; Poirier, Laurence; Amiard-Triquet, Claude; Amiard, Jean-Claude; Gaudin, Pierre; Risso-de Faverney, Christine; Guibbolini, Marielle; Gilliland, Douglas; Valsami-Jones, Eugenia; Mouneyrac, Catherine

2013-03-01

Because of their bactericidal effects, Ag nanoparticles (Ag NPs) have promising industrial development but could lead to potential ecological risks. The aim of this study was to examine the uptake and effect of silver (soluble or as lactate Ag NPs of 40 nm) at low concentrations (10 μg L(-1)) in the endobenthic bivalve Scrobicularia plana exposed, for 14 days, directly (water) or via the diet (microalgae). The stability of Ag NPs in seawater was examined using dynamic light scattering. Release of soluble Ag from Ag NPs in the experimental media was quantified by using diffusive gradient in thin film. Bioaccumulation of Ag in bivalves was measured by electrothermal atomic absorption spectrometry. Behavioural and biochemical biomarkers were determined in bivalves. Aggregation of Ag NPs and the release of soluble Ag from Ag NPs were observed in the experimental media. For both forms of Ag, bioaccumulation was much more important for waterborne than for dietary exposure. The response of oxidative stress biomarkers (catalase, glutathion S-transferase, superoxide dismutase) was more important after dietary than waterborne exposure to Ag (soluble and NPs). These defences were relatively efficient since they led to a lack of response of damage biomarkers. Burrowing was not affected for bivalves exposed directly or through the diet to both Ag forms but feeding behaviour was impaired after 10 days of dietary exposure. Since no differences of responses to Ag either soluble or nanoparticulate were observed, it seems that labile Ag released from Ag NPs was mainly responsible for toxicity. Copyright © 2012 Elsevier Inc. All rights reserved.

Low plasma selenium concentration is associated with elevated risk to neoplastic polyps of the colon

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, L.C.; Hixson, L.G.; Sampliner, R.E.

1991-03-11

A cross-sectional study was conducted to examine the relationship of selenium (Se) status and polyps incidence in a sequential series of 100 patients undergoing outpatient colonoscopies at the Tucson VA Hospital. Se was measured in plasma samples by electrothermal atomic absorption spectrophotometry with Zeeman background correction using a reduced palladium matrix modified. The activities of the Se-dependent enzyme glutathione peroxidase (SeGSHpx) were measured using H{sub 2}O{sub 2} as substrate in all plasma samples and in colonic mucosal biopsies obtained from some patients. The mean plasma Se concentration of patients without polyps was 134 ng/ml. Mean plasma Se levels of patientsmore » with only diminutive or large polyps were 127 ng/ml and 125 ng/ml; while patients with polyps of both sizes had a mean plasma Se level of 121 ng/ml. Patients with no reported history of cancer, neoplastic polyps or prior colonoscopy, showed an inverse association of plasma Se level and risk of benign colonic neoplasms. The age-adjusted odds ratio for neoplastic polyps was 3.8 for patients with plasma Se levels below vs. above the median value. This association was stronger for patients under 68 yrs of age than for older patients. Activities of SeGSHpx in plasma or colonic mucosa were not related to plasma Se level; however, smokers showed greater SeGSHpx activities than non-smokers. This study is the first to detect an association of Se status and risk to neoplastic polyps of the colon.« less

Pharmacokinetics of vanadium in humans after intravenous administration of a vanadium containing albumin solution

PubMed Central

Heinemann, Günter; Fichtl, Burckhard; Vogt, Wolfgang

2003-01-01

Aims Vanadium is currently undergoing clinical trials as an oral drug in patients with noninsulin-dependent diabetes mellitus. Furthermore, vanadium occurs in elevated concentrations in the blood of patients receiving intravenous albumin solutions containing large amounts of the metal ion as an impurity. The present study was performed to examine the pharmacokinetics of vanadium in humans following a single intravenous (i.v.) dose of a commercial albumin solution containing a high amount of vanadium. Methods The study was conducted in five healthy volunteer subjects who received intravenously 90 ml of a commercial 20% albumin infusion solution containing 47.6 µg vanadium as an impurity. Vanadium concentrations in serum and urine were determined by electrothermal atomic absorption spectrometry. Results Vanadium serum concentrations after i.v. administration were measured for 31 days. The data could be fitted by a triexponential function corresponding formally to a three-compartment model. There was an initial rapid decrease in serum concentrations with half-lives of 1.2 and 26 h. This was followed by a long-terminal half-life time of 10 days. The terminal phase accounted for about 80% of the total area under the serum concentration-time curve (AUC). The mean apparent volume of distribution of the central compartment was found to be 10 l. The volume of distribution at steady state was 54 l, and total clearance was 0.15 l h−1. Vanadium was mainly excreted by the kidneys. About 52% of the dose was recovered in the urine after 12 days. Conclusions This study provides data on vanadium pharmacokinetics in healthy humans. PMID:12630973

Dispersive liquid-liquid microextraction and preconcentration of thallium species in water samples by two ionic liquids applied as ion-pairing reagent and extractant phase.

PubMed

Escudero, Leticia B; Berton, Paula; Martinis, Estefanía M; Olsina, Roberto A; Wuilloud, Rodolfo G

2012-01-15

In the present work, a simple and highly sensitive analytical methodology for determination of Tl(+) and Tl(3+) species, based on the use of modern and non-volatile solvents, such as ionic liquids (ILs), was developed. Initially, Tl(+) was complexed by iodide ion at pH 1 in diluted sulfuric acid solution. Then, tetradecyl(trihexyl)phosphonium chloride ionic liquid (CYPHOS(®) IL 101) was used as ion-pairing reagent and a dispersive liquid-liquid microextraction (DLLME) procedure was developed by dispersing 60 mg of 1-hexyl-3-methylimidazolium hexafluorophosphate [C(6) mim][PF(6)] with 500 μL of ethanol in the aqueous solution. After the microextraction procedure was finished, the final IL phase was solubilized in methanol and directly injected into the graphite furnace of an electrothermal atomic absorption spectrometer (ETAAS). An extraction efficiency of 77% and a sensitivity enhancement factor of 100 were obtained with only 5.00 mL of sample. The limit of detection (LOD) was 3.3 ng L(-1) Tl while the relative standard deviation (RSD) was 5.3% (at 0.4 μg L(-1) Tl and n=10), calculated from the peak height of absorbance signals. The method was finally applied to determine Tl species in tap and river water samples after separation of Tl(3+) species. To the best of our knowledge, this work reports the first application of ILs for Tl extraction and separation in the analytical field. Copyright © 2011 Elsevier B.V. All rights reserved.

Respiratory effects in people exposed to arsenic via the drinking water and tobacco smoking in southern part of Pakistan.

PubMed

Arain, Muhammad Balal; Kazi, Tasneem Gul; Baig, Jameel Ahmed; Jamali, Muhammad Khan; Afridi, Hassan Imran; Jalbani, Nusrat; Sarfraz, Raja Adil; Shah, Abdul Qadir; Kandhro, Ghulam Abbas

2009-10-15

In this study, a survey has been conducted during 2005-2007 on surface and groundwater arsenic (As) contamination and its impact on the health of local population, of villages located on the banks of Manchar lake, southern part of Sindh, Pakistan. We have also assessed the relationship between arsenic exposure through respiratory disorders in male subjects with drinking water and smoking cigarettes made from tobacco grown in agricultural land irrigated with As contaminated lake water. The biological samples (blood and scalp hair) were collected from As exposed subjects (100% smokers) and age matched healthy male subjects (40.2% smoker and 59.8% non smokers) belong to unexposed areas for comparison purposes. The As concentration in drinking water (surface and underground water), agricultural soil, cigarette tobacco and biological samples were determined by electrothermal atomic absorption spectrometry. The range of As concentrations in lake water was 35.2-158 microg/L (average 97.5 microg/L), which is 3-15 folds higher than permissible limit of World Health Organization (WHO, 2004). While the As level in local cigarette tobacco was found to be 3-6 folds higher than branded cigarettes (0.37-0.79 microg/g). Arsenic exposed subjects (with and without RD) had significantly elevated levels of As in their biological samples as compared to referent male subject of unexposed area. These respiratory effects were more pronounced in individuals who had also As induced skin lesions. The linear regressions showed good correlations between As concentrations in water versus hair and blood samples of exposed subjects with and without respiratory problems.

Comparative studies on Pb and Cd levels in parasites of terrestrial and aquatic animals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sures, B.; Taraschewski, H.

1995-12-31

Several fish parasites (Acanthocephala, Cestoda, Nematoda) and organs of their respective intermediate and final hosts were analyzed for heavy metals by electrothermal atomic absorption spectrometry (ET-AAS). Pb and Cd were also quantified in the liver fluke Fasciola hepatica as well as in different organs of the large intestinal roundworm Ascaris suum. The levels of these heavy metals in the parasites were compared to those of muscle, liver, kidney and intestine of the respective definitive hosts cattle and swine obtained from a slaughter house. Most parasites accumulated significantly higher levels of metals than their final hosts. This was most conspicuous inmore » acanthocephalans which contained up to 3 {times} 10{sup 3} fold more lead than the muscle of their fish hosts and up to 1.1 {times} 10{sup 4} more lead than the water surrounding the fish. In these helminths cadmium was enriched up to 400 fold compared to the muscle of the fish and up to 2.7 {times} 10{sup 4} compared to the water. In contrast to the accumulation capacity of adult acanthocephalans their larvae contained about 30 to 180 times less Pb and Cd. Thus, the predominant accumulation of both metals appears in the adult worms. The cestodes of fish and the liver flukes of cattle accumulated the metals up to 200 fold compared to the muscle of their hosts. The nematodes did not contain higher levels of the metals than their hosts. Thus, parasites, especially acanthocephalans, seem to be sensitive bioindicators of Pb and Cd in their environments.« less

How conservative is arsenic in coastal marine environments? A study in Irish coastal waters

NASA Astrophysics Data System (ADS)

Anninou, Pinelopi; Cave, Rachel R.

2009-04-01

The conservative potential of arsenic in the relatively pristine waters of Galway Bay, an estuarine system in the west of Ireland, is examined through the inter-seasonal variations in the distribution of its total, hydride and non-hydride fractions. The arsenic concentrations in Galway Bay and local fresh water sources at all seasons were lower than what is considered the natural seawater concentration of 2 μg L -1 (27 nM). The effects of physical mixing, biological uptake and regeneration of arsenic on its distribution are considered. The degree of biological uptake and regeneration of the element are determined by a first order speciation between total arsenic (a small part of which should be of organic origin) and hydride arsenic (mostly of inorganic origin). The structural similarity of arsenic species to phosphate in seawater causes arsenic to be taken up by biota, which then have to detoxify it, so results are presented against phosphate to determine the degree of biological transformation of arsenic at different seasons. An in-house, batch type system of hydride generation coupled to electro-thermal atomic absorption spectrometry is used for the analysis of arsenic; this is preceded by UV-digestion prior to the measurement of total arsenic. Results show only a small association of arsenic with phosphate but a near linear, positive distribution pattern between arsenic and salinity in Galway Bay ( R2 ˜ 0.6), which is reproducible among seasons, indicating that in this environment the biological uptake of arsenic is likely to be a much slower process than the physical mixing of the water masses.

Determination of hexavalent chromium in exhaled breath condensate and environmental air among chrome plating workers

PubMed Central

Goldoni, Matteo; Caglieri, Andrea; Poli, Diana; Vettori, Maria Vittoria; Corradi, Massimo; Apostoli, Pietro; Mutti, Antonio

2006-01-01

Chromium speciation has attracted attention because of the different toxicity of Cr(III), which is considered relatively non-toxic, and Cr(VI), which can cross cell membranes mainly as a chromate anion and has been classified as a class I human carcinogen. The aims of the present study were to measure soluble Cr(VI) levels in environmental samples, to develop a simple method of quantifying Cr(VI) in exhaled breath condensate (EBC), and to follow the kinetics of EBC Cr(VI) in chrome plating workers. Personal air samples were collected from 10 chrome platers; EBC was collected from the same workers immediately after the work shift on Tuesday and before the work shift on the following Wednesday. Environmental and EBC Cr(VI) levels were determined by means of colorimetry and electrothermal absorption atomic spectrometry, respectively. The method of detecting Cr(VI) in environmental air was based on the extraction of the Cr(VI)-diphenylcarbazide (Cr(VI)–DPC) complex in 1-butanol, whereas EBC Cr(VI) was determined using a solvent extraction of Cr(VI) as an ion pair with tetrabutylammonium ion, and subsequent direct determination of the complex (Cr(VI)–DPC) in EBC. Kinetic data showed that airborne Cr(VI) was reduced by 50% in airway lining fluid sampled at the end of exposure and that there was a further 50% reduction after about 15 h. The persistence of Cr(VI) in EBC supports the use of EBC in assessing target tissue levels of Cr(VI). PMID:17047732

Methods for analysis of selected metals in water by atomic absorption

USGS Publications Warehouse

Fishman, Marvin J.; Downs, Sanford C.

1966-01-01

This manual describes atomic-absorption-spectroscopy methods for determining calcium, copper, lithium, magnesium, manganese, potassium, sodium, strontium and zinc in atmospheric precipitation, fresh waters, and brines. The procedures are intended to be used by water quality laboratories of the Water Resources Division of the U.S. Geological Survey. Detailed procedures, calculations, and methods for the preparation of reagents are given for each element along with data on accuracy, precision, and sensitivity. Other topics discussed briefly are the principle of atomic absorption, instrumentation used, and special analytical techniques.

Determination of palladium and platinum by atomic absorption

USGS Publications Warehouse

Schnepfe, M.M.; Grimaldi, F.S.

1969-01-01

Palladium and platinum are determined by atomic absorption after fire-assay concentration into a gold bead. The limit of determination is ~0??06 ppm in a 20-g sample. Serious depressive interelement interferences are removed by buffering the solutions with a mixture of cadmium and copper sulphates with cadmium and copper concentrations each at 0??5%. Substantial amounts of Ag, Al, Au, Bi, Ca, Co, Cr, Fe, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn, and the platinum metals do not interfere in the atomic-absorption determination. ?? 1969.

Anomalous small-angle scattering as a way to solve the Babinet principle problem

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boiko, M. E., E-mail: m.e.boiko@mail.ioffe.ru; Sharkov, M. D.; Boiko, A. M.

2013-12-15

X-ray absorption spectra (XAS) have been used to determine the absorption edges of atoms present in a sample under study. A series of small-angle X-ray scattering (SAXS) measurements using different monochromatic X-ray beams at different wavelengths near the absorption edges is performed to solve the Babinet principle problem. The sizes of clusters containing atoms determined by the method of XAS were defined in SAXS experiments. In contrast to differential X-ray porosimetry, anomalous SAXS makes it possible to determine sizes of clusters of different atomic compositions.

Anomalous small-angle scattering as a way to solve the Babinet principle problem

NASA Astrophysics Data System (ADS)

Boiko, M. E.; Sharkov, M. D.; Boiko, A. M.; Bobyl, A. V.

2013-12-01

X-ray absorption spectra (XAS) have been used to determine the absorption edges of atoms present in a sample under study. A series of small-angle X-ray scattering (SAXS) measurements using different monochromatic X-ray beams at different wavelengths near the absorption edges is performed to solve the Babinet principle problem. The sizes of clusters containing atoms determined by the method of XAS were defined in SAXS experiments. In contrast to differential X-ray porosimetry, anomalous SAXS makes it possible to determine sizes of clusters of different atomic compositions.

Analysis of high-purity germanium dioxide by ETV-ICP-AES with preliminary concentration of trace elements.

PubMed

Medvedev, Nickolay S; Shaverina, Anastasiya V; Tsygankova, Alphiya R; Saprykin, Anatoly I

2016-08-01

The paper presents a combined technique of germanium dioxide analysis by inductively coupled plasma atomic emission spectrometry (ICP-AES) with preconcentration of trace elements by distilling off matrix and electrothermal (ETV) introduction of the trace elements concentrate into the ICP. Evaluation of metrological characteristics of the developed technique of high-purity germanium dioxide analysis was performed. The limits of detection (LODs) for 25 trace elements ranged from 0.05 to 20ng/g. The accuracy of proposed technique is confirmed by "added-found" («or spiking») experiment and comparing the results of ETV-ICP-AES and ICP-AES analysis of high purity germanium dioxide samples. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of candidate working fluid formulations for the electrothermal-chemical wind tunnel

NASA Technical Reports Server (NTRS)

Akyurtlu, Jale F.; Akyurtlu, Ates

1993-01-01

A new hypersonic test facility which can simulate conditions typical of atmospheric flight at Mach numbers up to 20 is currently under study at the NASA/LaRC Hypersonic Propulsion Branch. In the proposed research, it was suggested that a combustion augmented electrothermal wind tunnel concept may be applied to the planned hypersonic testing facility. The purpose of the current investigation is to evaluate some candidate working fluid formulations which may be used in the chemical-electrothermal wind. The efforts in the initial phase of this research were concentrated on acquiring the code used by GASL to model the electrothermal wind tunnel and testing it using the conditions of GASL simulation. The early version of the general chemical kinetics code (GCKP84) was obtained from NASA and the latest updated version of the code (LSENS) was obtained from the author Dr. Bittker. Both codes are installed on a personal computer with a 486 25 MHz processor and 16 Mbyte RAM. Since the available memory was not sufficient to debug LSENS, for the current work GCKP84 was used.

Enhanced Reverse Saturable Absorption and Optical Limiting in Heavy-Atom Substituted Phthalocyanines

NASA Technical Reports Server (NTRS)

Perry, J. W.; Mansour, K.; Marder, S. R.; Alvarez, D., Jr.; Perry, K. J.; Choong, I.

1994-01-01

The reverse saturable absorption and optical limiting response of metal phthalocyaninies can be enhanced by using the heavy-atom effect. Phthalocyanines containing heavy metal atoms, such as In, Sn, and Pb show nearly a factor of two enhancement in the ratio of effective excited-state to ground-state absorption cross sections compared to those containing lighter atoms, such as Al and Si. In an f/8 optical geometry, homogeneous solutions of heavy metal phthalocyanines, at 30% linear transmission, limit 8-ns, 532-nm laser pulses to less than or equal to 3 (micro)J (the energy for 50% probability of eye damage) for incident pulses up to 800 (micro)J.

Mini-Column Ion-Exchange Separation and Atomic Absorption Quantitation of Nickel, Cobalt, and Iron: An Undergraduate Quantitative Analysis Experiment.

ERIC Educational Resources Information Center

Anderson, James L.; And Others

1980-01-01

Presents an undergraduate quantitative analysis experiment, describing an atomic absorption quantitation scheme that is fast, sensitive and comparatively simple relative to other titration experiments. (CS)

40 CFR Appendix G to Part 50 - Reference Method for the Determination of Lead in Suspended Particulate Matter Collected From...

Code of Federal Regulations, 2010 CFR

2010-07-01

... Absorption Spectroscopy.” Published by Interscience Company, New York, NY (1968). 5. Kirkbright, G. F., and Sargent, M., “Atomic Absorption and Fluorescence Spectroscopy.” Published by Academic Press, New York, NY... County, IL, by Atomic Absorption Spectroscopy.” Envir. Sci. and Tech., 3, 472-475 (1969). 7. “Proposed...

Direct determination and speciation of mercury compounds in environmental and biological samples by carbon bed atomic absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Skelly, E.M.

A method was developed for the direct determination of mercury in water and biological samples using a unique carbon bed atomizer for atomic absorption spectroscopy. The method avoided sources of error such as loss of volatile mercury during sample digestion and contamination of samples through added reagents by eliminating sample pretreatment steps. The design of the atomizer allowed use of the 184.9 nm mercury resonance line in the vacuum ultraviolet region, which increased sensitivity over the commonly used spin-forbidden 253.7 nm line. The carbon bed atomizer method was applied to a study of mercury concentrations in water, hair, sweat, urine,more » blood, breath and saliva samples from a non-occupationally exposed population. Data were collected on the average concentration, the range and distribution of mercury in the samples. Data were also collected illustrating individual variations in mercury concentrations with time. Concentrations of mercury found were significantly higher than values reported in the literature for a ''normal'' population. This is attributed to the increased accuracy gained by eliminating pretreatment steps and increasing atomization efficiency. Absorption traces were obtained for various solutions of pure and complexed mercury compounds. Absorption traces of biological fluids were also obtained. Differences were observed in the absorption-temperatures traces of various compounds. The utility of this technique for studying complexation was demonstrated.« less

Free radical propulsion concept

NASA Technical Reports Server (NTRS)

Hawkins, C. E.; Nakanishi, S.

1981-01-01

A free radical propulsion concept utilizing the recombination energy of dissociated low molecular weight gases to produce thrust was examined. The concept offered promise of a propulsion system operating at a theoretical impulse, with hydrogen, as high as 2200 seconds at high thrust to power ratio, thus filling the gas existing between chemical and electrostatic propulsion capabilities. Microwave energy used to dissociate a continuously flowing gas was transferred to the propellant via three body recombination for conversion to propellant kinetic energy. Power absorption by the microwave plasma discharge was in excess of 90 percent over a broad range of pressures. Gas temperatures inferred from gas dynamic equations showed much higher temperatures from microwave heating than from electrothermal heating. Spectroscopic analysis appeared to corroborate the inferred temperatures of one of the gases tested.

High enthalpy arc-heated plasma flow diagnostics by tunable diode laser absorption spectroscopy

NASA Astrophysics Data System (ADS)

Lin, Xin; Chen, Lianzhong; Zeng, Hui; Ou, Dongbin; Dong, Yonghui

2017-05-01

This paper reports the laser absorption measurements of atomic oxygen in the FD04 arc-heater at China Academy of Aerospace Aerodynamics (CAAA). An atomic oxygen absorption line at 777.19 nm is utilizied for detecting the population of electronically excited oxygen atom in an air plasma flow. A scanned-wavelength direct absorption mode is used in this study. The laser is scanned in wavelength across the absorption feature at a rate of 200 Hz. Under the assumption of thermal equilibrium, time-resolved temperature measurements are obtained on one line-of-sight in the arc-heater. The good agreement of the temperature inferred from the sonic throat method suggests the equilibrium assumption is valid. These results illustrate the feasibility of the diode laser sensors for flow parameters in high enthalpy arc-heated facilities.

Mercury in Environmental and Biological Samples Using Online Combustion with Sequential Atomic Absorption and Fluorescence Measurements: A Direct Comparison of Two Fundamental Techniques in Spectrometry

ERIC Educational Resources Information Center

Cizdziel, James V.

2011-01-01

In this laboratory experiment, students quantitatively determine the concentration of an element (mercury) in an environmental or biological sample while comparing and contrasting the fundamental techniques of atomic absorption spectrometry (AAS) and atomic fluorescence spectrometry (AFS). A mercury analyzer based on sample combustion,…

Electrode Arrangement As Substitute Bottom For An Electrothermic Slag Smelting Furnace.

DOEpatents

Aune, Jan Arthur; Brinch, Jon Christian; Johansen, Kai

2005-12-27

The electrode arrangement uses vertically oriented electrodes with side wall contacts for an electrothermic smelting furnace for aluminum production. The side wall contacts are radially moveable into the furnace to compensate for wear on the contacts. The side wall contacts can be hollow to allow a slag forming charge to be fed to the furnace.

Highly Enhanced Electromechanical Stability of Large-Area Graphene with Increased Interfacial Adhesion Energy by Electrothermal-Direct Transfer for Transparent Electrodes.

PubMed

Kim, Jangheon; Kim, Gi Gyu; Kim, Soohyun; Jung, Wonsuk

2016-09-07

Graphene, a two-dimensional sheet of carbon atoms in a hexagonal lattice structure, has been extensively investigated for research and industrial applications as a promising material with outstanding electrical, mechanical, and chemical properties. To fabricate graphene-based devices, graphene transfer to the target substrate with a clean and minimally defective surface is the first step. However, graphene transfer technologies require improvement in terms of uniform transfer with a clean, nonfolded and nontorn area, amount of defects, and electromechanical reliability of the transferred graphene. More specifically, uniform transfer of a large area is a key challenge when graphene is repetitively transferred onto pretransferred layers because the adhesion energy between graphene layers is too low to ensure uniform transfer, although uniform multilayers of graphene have exhibited enhanced electrical and optical properties. In this work, we developed a newly suggested electrothermal-direct (ETD) transfer method for large-area high quality monolayer graphene with less defects and an absence of folding or tearing of the area at the surface. This method delivers uniform multilayer transfer of graphene by repetitive monolayer transfer steps based on high adhesion energy between graphene layers and the target substrate. To investigate the highly enhanced electromechanical stability, we conducted mechanical elastic bending experiments and reliability tests in a highly humid environment. This ETD-transferred graphene is expected to replace commercial transparent electrodes with ETD graphene-based transparent electrodes and devices such as a touch panels with outstanding electromechanical stability.

Validation of NASA Thermal Ice Protection Computer Codes. Part 3; The Validation of Antice

NASA Technical Reports Server (NTRS)

Al-Khalil, Kamel M.; Horvath, Charles; Miller, Dean R.; Wright, William B.

2001-01-01

An experimental program was generated by the Icing Technology Branch at NASA Glenn Research Center to validate two ice protection simulation codes: (1) LEWICE/Thermal for transient electrothermal de-icing and anti-icing simulations, and (2) ANTICE for steady state hot gas and electrothermal anti-icing simulations. An electrothermal ice protection system was designed and constructed integral to a 36 inch chord NACA0012 airfoil. The model was fully instrumented with thermo-couples, RTD'S, and heat flux gages. Tests were conducted at several icing environmental conditions during a two week period at the NASA Glenn Icing Research Tunnel. Experimental results of running-wet and evaporative cases were compared to the ANTICE computer code predictions and are presented in this paper.

Method 200.12 - Determination of Trace Elements in Marine Waters by StabilizedTemperature Graphite Furnace Atomic Absorption

EPA Science Inventory

This method provides procedures for the determination of total recoverable elements by graphite furnace atomic absorption (GFAA) in marine waters, including estuarine, ocean and brines with salinities of up to 35 ppt.

Procedure for rapid determination of nickel, cobalt, and chromium in airborne particulate samples

NASA Technical Reports Server (NTRS)

Davis, W. F.; Graab, J. W.

1972-01-01

A rapid, selective procedure for the determination of 1 to 20 micrograms of nickel, chromium, and cobalt in airborne particulates is described. The method utilizes the combined techniques of low temperature ashing and atomic absorption spectroscopy. The airborne particulates are collected on analytical filter paper. The filter papers are ashed, and the residues are dissolved in hydrochloric acid. Nickel, chromium, and cobalt are determined directly with good precision and accuracy by means of atomic absorption. The effects of flame type, burner height, slit width, and lamp current on the atomic absorption measurements are reported.

Assessing the engagement, learning, and overall experience of students operating an atomic absorption spectrophotometer with remote access technology.

PubMed

Erasmus, Daniel J; Brewer, Sharon E; Cinel, Bruno

2015-01-01

The use of internet-based technologies in the teaching of laboratories has emerged as a promising education tool. This study evaluated the effectiveness of using remote access technology to operate an atomic absorption spectrophotometer in analyzing the iron content in a crude myoglobin extract. Sixty-two students were surveyed on their level of engagement, learning, and overall experience. Feedback from students suggests that the use of remote access technology is effective in teaching students the principles of chemical analysis by atomic absorption spectroscopy. © 2014 The International Union of Biochemistry and Molecular Biology.

Trace Element Analysis of Biological Samples.

ERIC Educational Resources Information Center

Veillon, Claude

1986-01-01

Reviews background of atomic absorption spectrometry techniques. Discusses problems encountered and precautions to be taken in determining trace elements in the parts-per-billion concentration range and below. Concentrates on determining chromium in biological samples by graphite furnace atomic absorption. Considers other elements, matrices, and…

Two-photon absorption laser-induced fluorescence of atomic oxygen in the afterglow of pulsed positive corona discharge

NASA Astrophysics Data System (ADS)

Ono, Ryo; Takezawa, Kei; Oda, Tetsuji

2009-08-01

Atomic oxygen is measured in the afterglow of pulsed positive corona discharge using time-resolved two-photon absorption laser-induced fluorescence. The discharge occurs in a 14 mm point-to-plane gap in dry air. After the discharge pulse, the atomic oxygen density decreases at a rate of 5×104 s-1. Simultaneously, ozone density increases at almost the same rate, where the ozone density is measured using laser absorption method. This agreement between the increasing rate of atomic oxygen and decreasing rate of ozone proves that ozone is mainly produced by the well-known three-body reaction, O+O2+M→O3+M. No other process for ozone production such as O2(v)+O2→O3+O is observed. The spatial distribution of atomic oxygen density is in agreement with that of the secondary streamer luminous intensity. This agreement indicates that atomic oxygen is mainly produced in the secondary streamer channels, not in the primary streamer channels.

VUV absorption spectroscopy measurements of the role of fast neutral atoms in a high-power gap breakdown

NASA Astrophysics Data System (ADS)

Filuk, A. B.; Bailey, J. E.; Cuneo, M. E.; Lake, P. W.; Nash, T. J.; Noack, D. D.; Maron, Y.

2000-12-01

The maximum power achieved in a wide variety of high-power devices, including electron and ion diodes, z pinches, and microwave generators, is presently limited by anode-cathode gap breakdown. A frequently discussed hypothesis for this effect is ionization of fast neutral atoms injected throughout the anode-cathode gap during the power pulse. We describe a newly developed diagnostic tool that provides a direct test of this hypothesis. Time-resolved vacuum-ultraviolet absorption spectroscopy is used to directly probe fast neutral atoms with 1-mm spatial resolution in the 10-mm anode-cathode gap of the SABRE 5 MV, 1 TW applied-B ion diode. Absorption spectra collected during Ar RF glow discharges and with CO2 gas fills confirm the reliability of the diagnostic technique. Throughout the 50-100 ns ion diode pulses no measurable neutral absorption was seen, setting upper limits of (0.12-1.5)×1014 cm-3 for ground-state fast neutral atom densities of H, C, N, O, and F. The absence of molecular absorption bands also sets upper limits of (0.16-1.2)×1015 cm-3 for common simple molecules. These limits are low enough to rule out ionization of fast neutral atoms as a breakdown mechanism. Breakdown due to ionization of molecules is also found to be unlikely. This technique can now be applied to quantify the role of neutral atoms in other high-power devices.

NARROW Na AND K ABSORPTION LINES TOWARD T TAURI STARS: TRACING THE ATOMIC ENVELOPE OF MOLECULAR CLOUDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pascucci, I.; Simon, M. N.; Edwards, S.

2015-11-20

We present a detailed analysis of narrow Na i and K i absorption resonance lines toward nearly 40 T Tauri stars in Taurus with the goal of clarifying their origin. The Na i λ5889.95 line is detected toward all but one source, while the weaker K i λ7698.96 line is detected in about two-thirds of the sample. The similarity in their peak centroids and the significant positive correlation between their equivalent widths demonstrate that these transitions trace the same atomic gas. The absorption lines are present toward both disk and diskless young stellar objects, which excludes cold gas within themore » circumstellar disk as the absorbing material. A comparison of Na i and CO detections and peak centroids demonstrates that the atomic gas and molecular gas are not co-located, the atomic gas being more extended than the molecular gas. The width of the atomic lines corroborates this finding and points to atomic gas about an order of magnitude warmer than the molecular gas. The distribution of Na i radial velocities shows a clear spatial gradient along the length of the Taurus molecular cloud filaments. This suggests that absorption is associated with the Taurus molecular cloud. Assuming that the gradient is due to cloud rotation, the rotation of the atomic gas is consistent with differential galactic rotation, whereas the rotation of the molecular gas, although with the same rotation axis, is retrograde. Our analysis shows that narrow Na i and K i absorption resonance lines are useful tracers of the atomic envelope of molecular clouds. In line with recent findings from giant molecular clouds, our results demonstrate that the velocity fields of the atomic and molecular gas are misaligned. The angular momentum of a molecular cloud is not simply inherited from the rotating Galactic disk from which it formed but may be redistributed by cloud–cloud interactions.« less

Fabrication of 3D electro-thermal micro actuators in silica glass by femtosecond laser wet etch and microsolidics

NASA Astrophysics Data System (ADS)

Li, Qichao; Shan, Chao; Yang, Qing; Chen, Feng; Bian, Hao; Hou, Xun

2017-02-01

This paper demonstrates a novel electro-thermal micro actuator's design, fabrication and device tests which combine microfluidic technology and microsolidics process. A three-dimensional solenoid microchannel with high aspect ratio is fabricated inside the silica glass by an improved femtosecond laser wet etch (FLWE) technology, and the diameter of the spiral coil is only 200 μm. Molten alloy (Bi/In/Sn/Pb) with high melting point is injected into the three-dimensional solenoid microchannel inside the silica glass , then it solidifys and forms an electro-thermal micro actuator. The device is capable of achieving precise temperature control and quick response, and can also be easily integrated into MEMS, sensors and `lab on a chip' (LOC) platform inside the fused silica substrate.

DETERMINATION OF TOTAL MERCURY IN FISH TISSUES USING PYROLYSIS ATOMIC ABSORPTION SPECTROMETRY WITH GOLD AMALGAMATION

EPA Science Inventory

A simple and rapid procedure for measuring total mercury in fish tissues is evaluated and
compared with conventional techniques. Using an automated instrument incorporating combustion, preconcentration by amalgamation with gold, and atomic absorption spectrometry (AAS), mill...

DETERMINING BERYLLIUM IN DRINKING WATER BY GRAPHITE FURNACE ATOMIC ABSORPTION SPECTROSCOPY

EPA Science Inventory

A direct graphite furnace atomic absorption spectroscopy method for the analysis of beryllium in drinking water has been derived from a method for determining beryllium in urine. Ammonium phosphomolybdate and ascorbic acid were employed as matrix modifiers. The matrix modifiers s...

The extreme wings of atomic emission and absorption lines. [in low pressure gases

NASA Technical Reports Server (NTRS)

Dalgarno, A.; Sando, K. M.

1973-01-01

Consideration of the extreme wings of atomic and molecular emission and absorption lines in low pressure gases. Classical and semiclassical results are compared with accurate quantal calculations of the self-broadening of Lyman-alpha in the hydrogen absorption spectrum that arises from quasimolecular transition. The results of classical, quantal, and semiclassical calculations of the absorption coefficient in the red wing are shown for temperatures of 500, 200, and 100 K. The semiclassical and quantal spectra agree well in shape at 500 K. Various other findings are discused.

Precision atomic beam density characterization by diode laser absorption spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oxley, Paul; Wihbey, Joseph

2016-09-15

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident lasermore » light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10{sup −5} are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10{sup 4} atoms cm{sup −3}. The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.« less

Precision atomic beam density characterization by diode laser absorption spectroscopy.

PubMed

Oxley, Paul; Wihbey, Joseph

2016-09-01

We provide experimental and theoretical details of a simple technique to determine absolute line-of-sight integrated atomic beam densities based on resonant laser absorption. In our experiments, a thermal lithium beam is chopped on and off while the frequency of a laser crossing the beam at right angles is scanned slowly across the resonance transition. A lock-in amplifier detects the laser absorption signal at the chop frequency from which the atomic density is determined. The accuracy of our experimental method is confirmed using the related technique of wavelength modulation spectroscopy. For beams which absorb of order 1% of the incident laser light, our measurements allow the beam density to be determined to an accuracy better than 5% and with a precision of 3% on a time scale of order 1 s. Fractional absorptions of order 10 -5 are detectable on a one-minute time scale when we employ a double laser beam technique which limits laser intensity noise. For a lithium beam with a thickness of 9 mm, we have measured atomic densities as low as 5 × 10 4 atoms cm -3 . The simplicity of our technique and the details we provide should allow our method to be easily implemented in most atomic or molecular beam apparatuses.

A comparative study of gamma-ray interaction and absorption in some building materials using Zeff-toolkit

NASA Astrophysics Data System (ADS)

Mann, Kulwinder Singh; Heer, Manmohan Singh; Rani, Asha

2016-07-01

The gamma-ray shielding behaviour of a material can be investigated by determining its various interaction and energy-absorption parameters (such as mass attenuation coefficients, mass energy absorption coefficients, and corresponding effective atomic numbers and electron densities). Literature review indicates that the effective atomic number (Zeff) has been used as extensive parameters for evaluating the effects and defect in the chosen materials caused by ionising radiations (X-rays and gamma-rays). A computer program (Zeff-toolkit) has been designed for obtaining the mean value of effective atomic number calculated by three different methods. A good agreement between the results obtained with Zeff-toolkit, Auto_Zeff software and experimentally measured values of Zeff has been observed. Although the Zeff-toolkit is capable of computing effective atomic numbers for both photon interaction (Zeff,PI) and energy absorption (Zeff,En) using three methods in each. No similar computer program is available in the literature which simultaneously computes these parameters simultaneously. The computed parameters have been compared and correlated in the wide energy range (0.001-20 MeV) for 10 commonly used building materials. The prominent variations in these parameters with gamma-ray photon energy have been observed due to the dominance of various absorption and scattering phenomena. The mean values of two effective atomic numbers (Zeff,PI and Zeff,En) are equivalent at energies below 0.002 MeV and above 0.3 MeV, indicating the dominance of gamma-ray absorption (photoelectric and pair production) over scattering (Compton) at these energies. Conversely in the energy range 0.002-0.3 MeV, the Compton scattering of gamma-rays dominates the absorption. From the 10 chosen samples of building materials, 2 soils showed better shielding behaviour than did other 8 materials.

Disentangling atomic-layer-specific x-ray absorption spectra by Auger electron diffraction spectroscopy

NASA Astrophysics Data System (ADS)

Matsui, Fumihiko; Matsushita, Tomohiro; Kato, Yukako; Hashimoto, Mie; Daimon, Hiroshi

2009-11-01

In order to investigate the electronic and magnetic structures of each atomic layer at subsurface, we have proposed a new method, Auger electron diffraction spectroscopy, which is the combination of x-ray absorption spectroscopy (XAS) and Auger electron diffraction (AED) techniques. We have measured a series of Ni LMM AED patterns of the Ni film grown on Cu(001) surface for various thicknesses. Then we deduced a set of atomic-layer-specific AED patterns in a numerical way. Furthermore, we developed an algorithm to disentangle XANES spectra from different atomic layers using these atomic-layer-specific AED patterns. Surface and subsurface core level shift were determined for each atomic layer.

Atomic-absorption determination of rhodium in chromite concentrates

USGS Publications Warehouse

Schnepfe, M.M.; Grimaldi, F.S.

1969-01-01

Rhodium is determined in chromite concentrates by atomic absorption after concentration either by co-precipitation with tellurium formed by the reduction of tellurite with tin(II) chloride or by fire assay into a gold bead. Interelement interferences in the atomic-absorption determination are removed by buffering the solutions with lanthanum sulphate (lanthanum concentration 1%). Substantial amounts of Ag, Al, Au, Bi, Ca, Cd, Co, Cr, Cu, Fe, Ho, Hg, K, La, Mg, Mn, Mo, Na, Ni, Pb, Te, Ti, V, Y, Zn and platinum metals can be tolerated. A lower limit of approximately 0.07 ppm Rh can be determined in a 3-g sample. ?? 1969.

Atomic Absorption Spectroscopy. The Present and the Future.

ERIC Educational Resources Information Center

Slavin, Walter

1982-01-01

The status of current techniques and methods of atomic absorption (AA) spectroscopy (flame, hybrid, and furnace AA) is discussed, including limitations. Technological opportunities and how they may be used in AA are also discussed, focusing on automation, microprocessors, continuum AA, hybrid analyses, and others. (Author/JN)

Tunable Diode Laser Atomic Absorption Spectroscopy for Detection of Potassium under Optically Thick Conditions.

PubMed

Qu, Zhechao; Steinvall, Erik; Ghorbani, Ramin; Schmidt, Florian M

2016-04-05

Potassium (K) is an important element related to ash and fine-particle formation in biomass combustion processes. In situ measurements of gaseous atomic potassium, K(g), using robust optical absorption techniques can provide valuable insight into the K chemistry. However, for typical parts per billion K(g) concentrations in biomass flames and reactor gases, the product of atomic line strength and absorption path length can give rise to such high absorbance that the sample becomes opaque around the transition line center. We present a tunable diode laser atomic absorption spectroscopy (TDLAAS) methodology that enables accurate, calibration-free species quantification even under optically thick conditions, given that Beer-Lambert's law is valid. Analyte concentration and collisional line shape broadening are simultaneously determined by a least-squares fit of simulated to measured absorption profiles. Method validation measurements of K(g) concentrations in saturated potassium hydroxide vapor in the temperature range 950-1200 K showed excellent agreement with equilibrium calculations, and a dynamic range from 40 pptv cm to 40 ppmv cm. The applicability of the compact TDLAAS sensor is demonstrated by real-time detection of K(g) concentrations close to biomass pellets during atmospheric combustion in a laboratory reactor.

Analysis of Dithiocarbamate Fungicides in Vegetable Matrices Using HPLC-UV Followed by Atomic Absorption Spectrometry.

PubMed

Al-Alam, Josephine; Bom, Laura; Chbani, Asma; Fajloun, Ziad; Millet, Maurice

2017-04-01

A simple method combining ion-pair methylation, high-performance liquid chromatography (HPLC) analysis with detection at 272 nm and atomic absorption spectrometry was developed in order to determine 10 dithiocarbamate fungicides (Dazomet, Metam-sodium, Ferbam, Ziram, Zineb, Maneb, Mancozeb, Metiram, Nabam and Propineb) and distinguish ethylenbisdithiocarbamates (EBDTCs) Zineb, Maneb and Mancozeb in diverse matrices. This method associates reverse phase analysis by HPLC analysis with detection at 272 nm, with atomic absorption spectrometry in order to distinguish, with the same extraction protocol, Maneb, Mancozeb and Zineb. The limits of detection (0.4, 0.8, 0.5, 1.25 and 1.97) and quantification (1.18, 2.5, 1.52, 4.2 and 6.52) calculated in injected nanogram, respectively, for Dazomet, Metam-Na, dimethyldithiocarbamates (DMDTCs), EBDTCs and propylenebisdithiocarbamates (PBDTCs) justify the sensitivity of the method used. The coefficients of determination R2 were 0.9985, 0.9978, 0.9949, 0.988 and 0.9794, respectively, for Dazomet, Metam-Na, DMDTCs, EBDTCs and PBDTCs, and the recovery from fortified apple and leek samples was above 90%. Results obtained with the atomic absorption method in comparison with spectrophotometric analysis focus on the importance of the atomic absorption as a complementary specific method for the distinction between different EBDTCs fungicides. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Development of 100 g Si and 250 g Ge detectors for a dark matter search

NASA Astrophysics Data System (ADS)

Brink, P. L.; Cabrera, B.; Chugg, B.; Clarke, R. M.; Davies, A.; Nam, S. W.; Young, B. A.

1996-05-01

Over the last two years we have proposed and implemented a new phonon sensing scheme for Cryogenic elementary particle detectors based upon Transition Edge Sensors (TES) operated in the (negative) Electrothermal-feedback (ETF) mode, and utilizing large Al collection pads for the initial phonon absorption. We have also implemented an ionization electrode, in addition to the phonon sensors, to allow the simultaneous measurement of ionization and phonon signals in Si and Ge absorbers. Our progress to date include successfully discriminating between electron and nuclear recoils down to a threshold of 4 keV recoil energy for a 4 g Si detector. Our first 100 g Si detectors have been fabricated, and initial work on Ge detectors indicates that our phonon sensing scheme will also work on large mass Ge absorbers.

Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm

NASA Technical Reports Server (NTRS)

Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.

1988-01-01

Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

Atomic and Molecular Gas Phase Spectrometry.

DTIC Science & Technology

1983-09-30

between the thermometric levels, k is the Boltzmann constant (k = 0.695 cm-I K-1 ), Aik (s- 1) is the transition probability for spontaneous emission from...monitoring of the atomic absorption of M; information about the reaction processes were deduced from the shapes of the titration curves; (5) measure- ment of...Changes During Titration Based Upon The Releasing Effect Atomic Absorption Spectroscopy," D. Stojanovic and J.D. Winefordner, Anal Chim. Acta, 114, 295

The Use of an Air-Natural Gas Flame in Atomic Absorption.

ERIC Educational Resources Information Center

Melucci, Robert C.

1983-01-01

Points out that excellent results are obtained using an air-natural gas flame in atomic absorption experiments rather than using an air-acetylene flame. Good results are obtained for alkali metals, copper, cadmium, and zinc but not for the alkaline earths since they form refractory oxides. (Author/JN)

COMPREHENSIVE ANALYSIS OF BIOLOGICALLY RELEVANT ARSENICALS BY PH-SELECTIVE HYDRIDE GENERATION-ATOMIC ABSORPTION SPECTROMETRY

EPA Science Inventory

A method based on pH-selective generation and separation of arsines is commonly used for analysis of inorganic, methylated, and dimethylated trivalent and pentavalent arsenicals by hydride generation-atomic absorption spectrometry (HG-AAS). We have optimized this method to pe...

[Atomic absorption in mercury determination by "Julia-2" analyzer and urine mercury level in children of Moscow suburbs].

PubMed

Pavlovskaia, N A; Vagina, E N; Stepanova, E V

2000-01-01

The authors report on atomic absorption method determining mercury in urine. Being sensitive, with lower determination threshold of 10 nmole/l and correctness of 95.5%, the method was tested on children living in two districts of Moscow suburb.

VUV absorption spectroscopy measurements of the role of fast neutral atoms in a high-power gap breakdown

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filuk, A. B.; Bailey, J. E.; Cuneo, M. E.

The maximum power achieved in a wide variety of high-power devices, including electron and ion diodes, z pinches, and microwave generators, is presently limited by anode-cathode gap breakdown. A frequently discussed hypothesis for this effect is ionization of fast neutral atoms injected throughout the anode-cathode gap during the power pulse. We describe a newly developed diagnostic tool that provides a direct test of this hypothesis. Time-resolved vacuum-ultraviolet absorption spectroscopy is used to directly probe fast neutral atoms with 1-mm spatial resolution in the 10-mm anode-cathode gap of the SABRE 5 MV, 1 TW applied-B ion diode. Absorption spectra collected duringmore » Ar RF glow discharges and with CO{sub 2} gas fills confirm the reliability of the diagnostic technique. Throughout the 50--100 ns ion diode pulses no measurable neutral absorption was seen, setting upper limits of (0.12--1.5)x10{sup 14}cm{sup -3} for ground-state fast neutral atom densities of H, C, N, O, and F. The absence of molecular absorption bands also sets upper limits of (0.16--1.2)x10{sup 15}cm{sup -3} for common simple molecules. These limits are low enough to rule out ionization of fast neutral atoms as a breakdown mechanism. Breakdown due to ionization of molecules is also found to be unlikely. This technique can now be applied to quantify the role of neutral atoms in other high-power devices.« less

Modeling and simulation of a 2-DOF bidirectional electrothermal microactuator

NASA Astrophysics Data System (ADS)

Topaloglu, N.; Elbuken, C.; Nieva, P. M.; Yavuz, M.; Huissoon, J. P.

2008-03-01

In this paper we present the modeling and simulation of a 2 degree-of-freedom (DOF) bidirectional electrothermal actuator. The four arm microactuator was designed to move in both the horizontal and vertical axes. By tailoring the geometrical parameters of the design, the in-plane and out-of-plane motions were decoupled, resulting in enhanced mobility in both directions. The motion of the actuator was modeled analytically using an electro-thermo-mechanical analysis. To validate the analytical model, finite element simulations were performed using ANSYS. The microactuators were fabricated using PolyMUMPS process and experimental results show good agreement with both the analytical model and the simulations. We demonstrated that the 2-DOF bidirectional electrothermal actuator can achieve 3.7 μm in-plane and 13.3 μm out-of-plane deflections with an input voltage of 10 V.

LEWICE 2.2 Capabilities and Thermal Validation

NASA Technical Reports Server (NTRS)

Wright, William B.

2002-01-01

A computational model of bleed air anti-icing and electrothermal de-icing have been added to the LEWICE 2.0 software by integrating the capabilities of two previous programs, ANTICE and LEWICE/ Thermal. This combined model has been released as LEWICE version 2.2. Several advancements have also been added to the previous capabilities of each module. This report will present the capabilities of the software package and provide results for both bleed air and electrothermal cases. A comprehensive validation effort has also been performed to compare the predictions to an existing electrothermal database. A quantitative comparison shows that for deicing cases, the average difference is 9.4 F (26%) compared to 3 F for the experimental data while for evaporative cases the average difference is 2 F (32%) compared to an experimental error of 4 F.

Confocal absorption spectral imaging of MoS2: optical transitions depending on the atomic thickness of intrinsic and chemically doped MoS2.

PubMed

Dhakal, Krishna P; Duong, Dinh Loc; Lee, Jubok; Nam, Honggi; Kim, Minsu; Kan, Min; Lee, Young Hee; Kim, Jeongyong

2014-11-07

We performed a nanoscale confocal absorption spectral imaging to obtain the full absorption spectra (over the range 1.5-3.2 eV) within regions having different numbers of layers and studied the variation of optical transition depending on the atomic thickness of the MoS2 film. Three distinct absorption bands corresponding to A and B excitons and a high-energy background (BG) peak at 2.84 eV displayed a gradual redshift as the MoS2 film thickness increased from the monolayer, to the bilayer, to the bulk MoS2 and this shift was attributed to the reduction of the gap energy in the Brillouin zone at the K-point as the atomic thickness increased. We also performed n-type chemical doping of MoS2 films using reduced benzyl viologen (BV) and the confocal absorption spectra modified by the doping showed a strong dependence on the atomic thickness: A and B exciton peaks were greatly quenched in the monolayer MoS2 while much less effect was shown in larger thickness and the BG peak either showed very small quenching for 1 L MoS2 or remained constant for larger thicknesses. Our results indicate that confocal absorption spectral imaging can provide comprehensive information on optical transitions of microscopic size intrinsic and doped two-dimensional layered materials.

Ultraviolet absorption: Experiment MA-059. [measurement of atmospheric species concentrations

NASA Technical Reports Server (NTRS)

Donahue, T. M.; Hudson, R. D.; Rawlins, W. T.; Anderson, J.; Kaufman, F.; Mcelroy, M. B.

1977-01-01

A technique devised to permit the measurement of atmospheric species concentrations is described. This technique involves the application of atomic absorption spectroscopy and the quantitative observation of resonance fluorescence in which atomic or molecular species scatter resonance radiation from a light source into a detector. A beam of atomic oxygen and atomic nitrogen resonance radiation, strong unabsorbable oxygen and nitrogen radiation, and visual radiation was sent from Apollo to Soyuz. The density of atomic oxygen and atomic nitrogen between the two spacecraft was measured by observing the amount of resonance radiation absorbed when the line joining Apollo and Soyuz was perpendicular to their velocity with respect to the ambient atmosphere. Results of postflight analysis of the resonance fluorescence data are discussed.

Magnetomotive room temperature dicationic ionic liquid: a new concept toward centrifuge-less dispersive liquid-liquid microextraction.

PubMed

Beiraghi, Asadollah; Shokri, Masood; Seidi, Shahram; Godajdar, Bijan Mombani

2015-01-09

A new centrifuge-less dispersive liquid-liquid microextraction technique based on application of magnetomotive room temperature dicationic ionic liquid followed by electrothermal atomic absorption spectrometry (ETAAS) was developed for preconcentration and determination of trace amount of gold and silver in water and ore samples, for the first time. Magnetic ionic liquids not only have the excellent properties of ionic liquids but also exhibit strong response to an external magnetic field. These properties provide more advantages and potential application prospects for magnetic ionic liquids than conventional ones in the fields of extraction processes. In this work, thio-Michler's ketone (TMK) was used as chelating agent to form Ag/Au-TMK complexes. Several important factors affecting extraction efficiency including extraction time, rate of vortex agitator, pH of sample solution, concentration of the chelating agent, volume of ionic liquid as well as effects of interfering species were investigated and optimized. Under the optimal conditions, the limits of detection (LOD) were 3.2 and 7.3ngL(-1) with the preconcentration factors of 245 and 240 for Au and Ag, respectively. The precision values (RSD%, n=7) were 5.3% and 5.8% at the concentration level of 0.05μgL(-1) for Au and Ag, respectively. The relative recoveries for the spiked samples were in the acceptable range of 96-104.5%. The results demonstrated that except Hg(2+), no remarkable interferences are created by other various ions in the determination of Au and Ag, so that the tolerance limits (WIon/WAu or Ag) of major cations and anions were in the range of 250-1000. The validated method was successfully applied for the analysis of Au and Ag in some water and ore samples. Copyright © 2014 Elsevier B.V. All rights reserved.

Ultrastructural study of liver and lead tissue concentrations in young mallard ducks (Anas platyrhynchos) after ingestion of single lead shot.

PubMed

Pineau, Alain; Fauconneau, Bernard; Plouzeau, Eric; Fernandez, Béatrice; Quellard, Nathalie; Levillain, Pierre; Guillard, Olivier

2017-01-01

Lead (Pb) represents a serious threat to wildlife and ecosystems. The aim of this study was to examine the subcellular effects of dietary Pb pellet ingestion on mallard (Anas platyrhynchos) livers. After ingestion of a single Pb shot (LS4 size class: 0.177 ± 0.03 g) in 41 mallard ducks (22 males and 19 females) versus 10 controls (5 males and 5 females), all 7-week old, a morphologic study was conducted by TEM (transmission electron microscopy) of liver at the subcellular level. The results in treated mallards showed at a magnification of 2500 X that hepatic parenchyma was altered as evidenced by intralysosomal electron-dense deposits, which are compatible with Pb deposits. Further, at a higher magnification (15,000 X) in both genders, deterioration of mitochondria was observed in which the crests and, to a lesser extent, outer membrane were lysed. While the rough endoplasmic reticulum was fragmented, intracytoplasmic electron-dense material compatible with Pb deposits was maximally visible, thereby underscoring the deeply destructive effect of this metal on the subcellular architecture of the liver. In addition, applying an optimized and validated method in a clean room using electrothermal atomic absorption spectrophotometer (ETAAS) with Zeeman background correction, the objective was to improve and refine certain indispensable measurements pertaining to Pb impregnation in tissues other than liver such as kidneys, bones, and feathers of mallards. Data demonstrated show that compared with controls, Pb accumulation increases significantly, not only in the liver (3-fold), but also in the bones and the feathers (14-fold). No significant difference was noted between males and females. Bearing in mind the marked subcellular toxicity attributed to Pb, this study reinforces present-day arguments advocating limitation of game consumption.

Response surface methodology based on central composite design as a chemometric tool for optimization of dispersive-solidification liquid-liquid microextraction for speciation of inorganic arsenic in environmental water samples.

PubMed

Asadollahzadeh, Mehdi; Tavakoli, Hamed; Torab-Mostaedi, Meisam; Hosseini, Ghaffar; Hemmati, Alireza

2014-06-01

Dispersive-solidification liquid-liquid microextraction (DSLLME) coupled with electrothermal atomic absorption spectrometry (ETAAS) was developed for preconcentration and determination of inorganic arsenic (III, V) in water samples. At pH=1, As(III) formed complex with ammonium pyrrolidine dithiocarbamate (APDC) and extracted into the fine droplets of 1-dodecanol (extraction solvent) which were dispersed with ethanol (disperser solvent) into the water sample solution. After extraction, the organic phase was separated by centrifugation, and was solidified by transferring into an ice bath. The solidified solvent was transferred to a conical vial and melted quickly at room temperature. As(III) was determined in the melted organic phase while As(V) remained in the aqueous layer. Total inorganic As was determined after the reduction of the pentavalent forms of arsenic with sodium thiosulphate and potassium iodide. As(V) was calculated by difference between the concentration of total inorganic As and As(III). The variable of interest in the DSLLME method, such as the volume of extraction solvent and disperser solvent, pH, concentration of APDC (chelating agent), extraction time and salt effect, was optimized with the aid of chemometric approaches. First, in screening experiments, fractional factorial design (FFD) was used for selecting the variables which significantly affected the extraction procedure. Afterwards, the significant variables were optimized using response surface methodology (RSM) based on central composite design (CCD). In the optimum conditions, the proposed method has been successfully applied to the determination of inorganic arsenic in different environmental water samples and certified reference material (NIST RSM 1643e). Copyright © 2014 Elsevier B.V. All rights reserved.

Evaluated the adverse effects of cadmium and aluminum via drinking water to kidney disease patients: Application of a novel solid phase microextraction method.

PubMed

Panhwar, Abdul Haleem; Kazi, Tasneem Gul; Naeemullah; Afridi, Hassan Imran; Shah, Faheem; Arain, Mohammad Balal; Arain, Salma Aslam

2016-04-01

In present study aluminum (Al) and cadmium (Cd) were determined in ground water samples and assesses human health risks associated with elevated concentrations of toxic metals in dissolved form, using a novel solid phase microextraction (SPμE). Ground water sample (n=200) and biological sample (blood) of patients having chronic kidney disorders (CKD) along with healthy control subjects of same area (southern part of Pakistan) were collected. A simple system, including the micropipette tip packed with modified ionic liquid-activated carbon cloth (IL-ACC) coated with 8-hydroxyqunilone (8-HQ) attached to syringe. The analytes in water and acid digested blood samples were manually drawn for 2-10 cycles (drawing/discharging) at different pH range. The analytes sorbed on coated ACC were then desorbed with 2.0molL(-1) HNO3 in ethanol by drawing/discharging cycles for 1-5 times. The concentration of extracted analytes was determined by electrothermal atomic absorption spectrometer. The influence of different variables on the extraction efficiency of Cd and Al, were optimized. The Al and Cd concentrations in groundwater were found to be elevated than recommended limits by the World Health Organization. The urinary N-acetyl-h-glucosaminidase values were significantly higher in CKD patients as compared to refrent subjects (p<0.001). The significant variation in levels of Cd and Al were observed in blood samples of CKD patients than referents subjects (p<0.01). The strong positive correlation among Al and Cd levels in groundwater versus blood samples of CKD patients (r=0.82-0.85) p<0.01) was observed than those values calculated for referent subjects (r=0.425-0.536). Copyright © 2016 Elsevier B.V. All rights reserved.

The oxidation of Cr(III) to Cr(VI) in the environment by atmospheric oxygen during the bush fires.

PubMed

Panichev, N; Mabasa, W; Ngobeni, P; Mandiwana, K; Panicheva, S

2008-05-30

The presence of Cr(VI) in soils and plants of remote unpolluted areas can be explained by partial oxidation of Cr(III) with atmospheric oxygen during seasonable bush fires, which are rather frequent event in South Africa. Experiments with thermal treatment of a veld grass, Hyperthelia dissoluta, in muffle furnace at high temperature, followed by electrothermal atomic absorption spectrometry (ETAAS) determination of chromium, show a remarkable increase in Cr(VI) concentration from initial 2.5 to 23.2% after the treatment of grass ash at 500 degrees C and to 58.1% at 900 degrees C. Before ETAAS determination, the two chromium species of interest were separated by the treatment of samples with 0.1M Na2CO3. Thermodynamic calculations confirm the possibility of Cr(III) to Cr(VI) oxidation with atmospheric oxygen at high temperature in alkaline media, which is typical for vegetation ash. Analysis of field samples show that percent of Cr(VI), in respect to the total amount of chromium increased from initial 2.5% in grass to 9.3% in ash of grass. Without oxidation the percent of Cr(VI) in grass and ash of grass should be a constant value. After the fire Cr(VI) concentration in top soil (0-3 cm) increased from 0.3+/-0.05 to 1.8+/-0.5 microg g(-1) and the total Cr from 26+/-9 to 69+/-14 microg g(-1). The reason for the appearance of additional amount of Cr on top soil can be explained by condensation of chromium species from flame and shouldering ash on a soil surface. The results of studies demonstrate that Cr(VI) is formed by Cr(III) oxidation with atmospheric oxygen at high temperature during bush fires.

Hazardous impact and translocation of vanadium (V) species from soil to different vegetables and grasses grown in the vicinity of thermal power plant.

PubMed

Khan, Sumaira; Kazi, Tasneem Gul; Kolachi, Nida Fatima; Baig, Jameel Ahmed; Afridi, Hassan Imran; Shah, Abdul Qadir; Kumar, Sham; Shah, Faheem

2011-06-15

The distribution of vanadium (V) species in soil (test soil), vegetables and grasses, collected from the vicinity of a thermal power plant has been studied. For comparison purpose soil (control soil), same vegetable and grass samples were collected from agricultural land devoid of any industrial area. A simple and efficient ultrasonic assisted extraction method has been developed for the extraction of V(5+) species from soil, vegetable and grass samples using Na(2)CO(3) in the range of 0.1-0.5 mol/L. For comparison purpose same sub samples were also extracted by conventional heating method. The total and V species were determined by electrothermal atomic absorption spectrometry using different modifiers. The validity of V(5+) and V(4+) determination had been confirmed by the spike recovery and total amount of V by the analysis of CRM 1570 (spinach leave) and sub samples of agricultural soil. The concentration of total V was found in the range of 90-215 and 11.4-42.3 μg/g in test and control soil samples, respectively. The contents of V(5+) and total V in vegetables and grasses grown around the thermal power plant were found in the range of 2.9-5.25 and 8.74-14.9 μg/g, respectively, which were significantly higher than those values obtained from vegetables and fodders grown in non exposed agricultural site (P<0.01). Statistical evaluations indicate that the sum of concentrations of V(5+) and V(4+) species was not significantly different from total concentration of V in same sub samples of vegetable, grass and soil of both origins, at 95% level of confidence. Copyright © 2011 Elsevier B.V. All rights reserved.

Monitoring of trace elements in breast milk sampling and measurement procedures.

PubMed

Spĕvácková, V; Rychlík, S; Cejchanová, M; Spĕvácek, V

2005-06-01

The aims of this study were to test analytical procedures for the determination of Cd, Cu, Mn, Pb, Se and Zn in breast milk and to establish optimum sampling conditions for monitoring purposes. Two population groups were analysed: (1) Seven women from Prague whose breast milk was sampled on days 1,2, 3, 4, 10, 20 and 30 after delivery; (2) 200 women from four (two industrial and two rural) regions whose breast milk was sampled at defined intervals. All samples were mineralised in a microwave oven in the mixture of HNO3 + H2O2 and analysed by atomic absorption spectrometry. Conditions for the measurement of the elements under study (i.e. those for the electrothermal atomisation for Cd, Mn and Pb, flame technique for Cu and Zn, and hydride generation technique for Se) were optimized. Using optimized parameters the analysis was performed and the following conclusion has been made: the concentrations of zinc and manganese decreased very sharply over the first days, that of copper slightly increased within the first two days and then slightly decreased, that of selenium did not change significantly. Partial "stabilisation" was achieved after the second decade. No correlation among the elements was found. A significant difference between whole and skim milk was only found for selenium (26% rel. higher in whole milk). The majority concentrations of cadmium and lead were below the detection limit of the method (0.3 microg x l(-1) and 8.2 microg x l(-1), respectively, as calculated for the original sample). To provide biological monitoring, the maintenance of sampling conditions and especially the time of sampling is crucial.

The correlation of arsenic levels in drinking water with the biological samples of skin disorders.

PubMed

Kazi, Tasneem Gul; Arain, Muhammad Balal; Baig, Jameel Ahmed; Jamali, Muhammad Khan; Afridi, Hassan Imran; Jalbani, Nusrat; Sarfraz, Raja Adil; Shah, Abdul Qadir; Niaz, Abdul

2009-01-15

Arsenic (As) poisoning has become a worldwide public health concern. The skin is quite sensitive to As and skin lesions are the most common and earliest nonmalignant effects associated to chronic As exposure. In 2005-2007, a survey was carried out on surface and groundwater arsenic contamination and relationships between As exposure via the drinking water and related adverse health effects (melanosis and keratosis) on villagers resides on the banks of Manchar lake, southern part of Sindh, Pakistan. We screened the population from arsenic-affected villages, 61 to 73% population were identified patients suffering from chronic arsenic toxicity. The effects of As toxicity via drinking water were estimated by biological samples (scalp hair and blood) of adults (males and females), have or have not skin problem (n=187). The referent samples of both genders were also collected from the areas having low level of As (<10 microg/L) in drinking water (n=121). Arsenic concentration in drinking water and biological samples were analyzed using electrothermal atomic absorption spectrometry. The range of arsenic concentrations in lake surface water was 35.2-158 microg/L, which is 3-15 folds higher than World Health Organization [WHO, 2004. Guidelines for drinking-water quality third ed., WHO Geneva Switzerland.]. It was observed that As concentration in the scalp hair and blood samples were above the range of permissible values 0.034-0.319 microg As/g for hair and <0.5-4.2 microg/L for blood. The linear regressions showed good correlations between arsenic concentrations in water versus hair and blood samples of exposed skin diseased subjects (R2=0.852 and 0.718) as compared to non-diseased subjects (R2=0.573 and 0.351), respectively.

Urinary nickel excretion in populations living in the proximity of two russian nickel refineries: a Norwegian-Russian population-based study.

PubMed Central

Smith-Sivertsen, T; Tchachtchine, V; Lund, E; Bykov, V; Thomassen, Y; Norseth, T

1998-01-01

The Russian nickel refineries located in the cities of Nikel and Zapolyarny close to the Norwegian border are responsible for extensive sulfur dioxide and nickel pollution, as well as severe ecological damage in both countries. The aim of our study was to investigate human nickel exposure in the populations living on both sides of the Norwegian-Russian border. The design was a cross-sectional population-based study of adults aged 18-69 years residing in Sor-Varanger municipality, Norway, and Nikel and Zapolyarny, Russia, during 1994 and 1995. Individual exposure to nickel was assessed by measurements of nickel in urine using electrothermal atomic absorption spectrometry. For controls, urine was collected from adults in the Russian cities of Apatity and Umba (Kola Peninsula) and the Norwegian city of Tromso, all of which are locations without nearby point sources of nickel. Altogether 2,233 urine specimens were analysed for nickel. People living in Nikel had the highest concentrations (median 3.4 microg/l), followed by Umba (median 2.7 microg/l), Zapolyarny (median 2.0 microg/l), Apatity (median 1.9 microg/l), Tromso (median 1.2 microg/l), and Sor-Varanger (median 0.6 microg/l). Regardless of geographical location, the Russian study groups all had a higher urinary-nickel average than those in Norway (p<0.001). With the exception of Nikel, neither the Russian nor the Norwegian urinary-nickel levels were associated with residence location near a Russian nickel refinery. We concluded that industrial nickel pollution alone could not explain the observed discrepancy between Norway and Russia; we also discuss other possible nickel exposure sources that may account for the high urinary levels found in Russia. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 PMID:9681979

Analytical evidence of heterogeneous lead accumulation in the hypothalamic defence area and nucleus tractus solitarius.

PubMed

Guimarães, D; Santos, J P; Carvalho, M L; Diniz, M S; House, B; Miller, V M

2014-09-01

Lead is a potent toxicant associated with adverse cardiovascular effects and hypertension in children. Yet, few studies have determined if autonomic dysfunction associated with lead exposure involves brain regions which regulate autonomic responses. Central autonomic nuclei such as the nucleus tractus solitarius (NTS) and hypothalamic defence area (HDA) may be particularly sensitive to lead infiltration because they are adjacent to ventricles and areas with semi-permeable blood-brain-barriers. To understand if autonomic nuclei are sensitive to lead accumulation Wistar rats were exposed to lead from the gestational period and lead levels were quantified in brain regions that regulate arterial pressure: the NTS and the HDA. Energy dispersive X-ray fluorescence (EDXRF) was used to quantify total brain lead levels and revealed no differences between exposed and control tissues; measured values were close to the detection limit (2μg/g). Electrothermal atomic absorption spectrometry (ETAAS) was also used, which has a greater sensitivity, to quantify lead. There was ∼2.1μg/g lead in the NTS and ∼3.1μg/g lead in the HDA of exposed rats, and no lead in the control rats. There were greater lead levels in the HDA (∼50%) as compared with the NTS. Pathology studies revealed more prominent lead granules in the HDA as compared with the NTS. Increased microglia and astrocyte activation was also noted in the NTS of lead exposed rats as compared with the HDA. Regional differences in neuro-inflammatory responses likely contribute to heterogeneous lead accumulation, with enhanced clearance of lead in the NTS. Future studies will resolve the mechanisms underpinning tissue-specific lead accumulation. Copyright © 2014 Elsevier Inc. All rights reserved.

The effect of different propolis harvest methods on its lead contents determined by ET AAS and UV-visS.

PubMed

Sales, A; Alvarez, A; Areal, M Rodriguez; Maldonado, L; Marchisio, P; Rodríguez, M; Bedascarrasbure, E

2006-10-11

Argentinean propolis is exported to different countries, specially Japan. The market demands propolis quality control according to international standards. The analytical determination of some metals, as lead in food, is very important for their high toxicity even in low concentrations and because of their harmful effects on health. Flavonoids, the main bioactive compounds of propolis, tend to chelate metals as lead, which becomes one of the main polluting agents of propolis. The lead found in propolis may come from the atmosphere or it may be incorporated in the harvest, extraction and processing methods. The aim of this work is to evaluate lead level on Argentinean propolis determined by electrothermal atomic absorption spectrometry (ET AAS) and UV-vis spectrophotometry (UV-visS) methods, as well as the effect of harvest methods on those contents. A randomized test with three different treatments of collection was made to evaluate the effect of harvest methods. These procedures were: separating wedges (traditional), netting plastic meshes and stamping out plastic meshes. By means of the analysis of variance technique for multiple comparisons (ANOVA) it was possible to conclude that there are significant differences between scraped and mesh methods (stamped out and mosquito netting meshes). The results obtained in the present test would allow us to conclude that mesh methods are more advisable than scraped ones in order to obtain innocuous and safe propolis with minor lead contents. A statistical comparison of lead determination by both, ET AAS and UV-visS methods, demonstrated that there is not a significant difference in the results achieved with the two analytical techniques employed.

Temperature mapping and thermal dose calculation in combined radiation therapy and 13.56 MHz radiofrequency hyperthermia for tumor treatment

NASA Astrophysics Data System (ADS)

Kim, Jung Kyung; Prasad, Bibin; Kim, Suzy

2017-02-01

To evaluate the synergistic effect of radiotherapy and radiofrequency hyperthermia therapy in the treatment of lung and liver cancers, we studied the mechanism of heat absorption and transfer in the tumor using electro-thermal simulation and high-resolution temperature mapping techniques. A realistic tumor-induced mouse anatomy, which was reconstructed and segmented from computed tomography images, was used to determine the thermal distribution in tumors during radiofrequency (RF) heating at 13.56 MHz. An RF electrode was used as a heat source, and computations were performed with the aid of the multiphysics simulation platform Sim4Life. Experiments were carried out on a tumor-mimicking agar phantom and a mouse tumor model to obtain a spatiotemporal temperature map and thermal dose distribution. A high temperature increase was achieved in the tumor from both the computation and measurement, which elucidated that there was selective high-energy absorption in tumor tissue compared to the normal surrounding tissues. The study allows for effective treatment planning for combined radiation and hyperthermia therapy based on the high-resolution temperature mapping and high-precision thermal dose calculation.

Theoretical analysis of non-linear Joule heating effects over an electro-thermal patterned flow

NASA Astrophysics Data System (ADS)

Sanchez, Salvador; Ascanio, Gabriel; Mendez, Federico; Bautista, Oscar

2017-11-01

In this work, non-linear Joule heating effects for electro-thermal patterned flows driven inside of a slit microchannel are analyzed. Here, the movement of fluids is controlled by placing electro-thermal forces, which are generated through an imposed longitudinal electric field, E0, and the wall electric potential produced by electrodes inserted along the surface of the microchannel wall, ζ. For this analysis, viscosity and electrical conductivity of fluids are included as known functions, which depend on the temperature; therefore, in order to determine the flow, temperature and electric potential fields together with its simultaneous interactions, the equations of continuity, momentum, energy, charges distribution and electrical current have to be solved in a coupled manner. The main results obtained in the study reveal that with the presence of thermal gradients along of the microchannel, local electro-thermal forces, Fχ, are affected in a sensible manner, and consequently, the flow field is modified substantially, causing the interruption or intensification of recirculations along of the microchannel. This work was supported by the Fondo SEP-CONACYT through research Grants No. 220900 and 20171181 from SIP-IPN. F. Mendez acknowledges support from PAPIIT-UNAM under Contract Number IN112215. S. Sanchez thanks to DGAPA-UNAM for the postdoctoral fellowship.

Design and Characterization of a High Resolution Microfluidic Heat Flux Sensor with Thermal Modulation

PubMed Central

Nam, Sung-Ki; Kim, Jung-Kyun; Cho, Sung-Cheon; Lee, Sun-Kyu

2010-01-01

A complementary metal-oxide semiconductor-compatible process was used in the design and fabrication of a suspended membrane microfluidic heat flux sensor with a thermopile for the purpose of measuring the heat flow rate. The combination of a thirty-junction gold and nickel thermoelectric sensor with an ultralow noise preamplifier, a low pass filter, and a lock-in amplifier can yield a resolution 20 nW with a sensitivity of 461 V/W. The thermal modulation method is used to eliminate low-frequency noise from the sensor output, and various amounts of fluidic heat were applied to the sensor to investigate its suitability for microfluidic applications. For sensor design and analysis of signal output, a method of modeling and simulating electro-thermal behavior in a microfluidic heat flux sensor with an integrated electronic circuit is presented and validated. The electro-thermal domain model was constructed by using system dynamics, particularly the bond graph. The electro-thermal domain system model in which the thermal and the electrical domains are coupled expresses the heat generation of samples and converts thermal input to electrical output. The proposed electro-thermal domain system model is in good agreement with the measured output voltage response in both the transient and the steady state. PMID:22163568

Electrothermally Driven Fluorescence Switching by Liquid Crystal Elastomers Based On Dimensional Photonic Crystals.

PubMed

Lin, Changxu; Jiang, Yin; Tao, Cheng-An; Yin, Xianpeng; Lan, Yue; Wang, Chen; Wang, Shiqiang; Liu, Xiangyang; Li, Guangtao

2017-04-05

In this article, the fabrication of an active organic-inorganic one-dimensional photonic crystal structure to offer electrothermal fluorescence switching is described. The film is obtained by spin-coating of liquid crystal elastomers (LCEs) and TiO 2 nanoparticles alternatively. By utilizing the property of LCEs that can change their size and shape reversibly under external thermal stimulations, the λ max of the photonic band gap of these films is tuned by voltage through electrothermal conversion. The shifted photonic band gap further changes the matching degree between the photonic band gap of the film and the emission spectrum of organic dye mounting on the film. With rhodamine B as an example, the enhancement factor of its fluorescence emission is controlled by varying the matching degree. Thus, the fluorescence intensity is actively switched by voltage applied on the system, in a fast, adjustable, and reversible manner. The control chain of using the electrothermal stimulus to adjust fluorescence intensity via controlling the photonic band gap is proved by a scanning electron microscope (SEM) and UV-vis reflectance. This mechanism also corresponded to the results from the finite-difference time-domain (FDTD) simulation. The comprehensive usage of photonic crystals and liquid crystal elastomers opened a new possibility for active optical devices.

Beyond the single-atom response in absorption line shapes: probing a dense, laser-dressed helium gas with attosecond pulse trains.

PubMed

Liao, Chen-Ting; Sandhu, Arvinder; Camp, Seth; Schafer, Kenneth J; Gaarde, Mette B

2015-04-10

We investigate the absorption line shapes of laser-dressed atoms beyond the single-atom response, by using extreme ultraviolet (XUV) attosecond pulse trains to probe an optically thick helium target under the influence of a strong infrared (IR) field. We study the interplay between the IR-induced phase shift of the microscopic time-dependent dipole moment and the resonant-propagation-induced reshaping of the macroscopic XUV pulse. Our experimental and theoretical results show that as the optical depth increases, this interplay leads initially to a broadening of the IR-modified line shape, and subsequently, to the appearance of new, narrow features in the absorption line.

Determination of the atomic density of rubidium-87

NASA Astrophysics Data System (ADS)

Zhao, Meng; Zhang, Kai; Chen, Li-Qing

2015-09-01

Atomic density is a basic and important parameter in quantum optics, nonlinear optics, and precision measurement. In the past few decades, several methods have been used to measure atomic density, such as thermionic effect, optical absorption, and resonance fluorescence. The main error of these experiments stemmed from depopulation of the energy level, self-absorption, and the broad bandwidth of the laser. Here we demonstrate the atomic density of 87Rb vapor in paraffin coated cell between 297 K and 334 K mainly using fluorescence measurement. Optical pumping, anti-relaxation coating, and absorption compensation approaches are used to decrease measurement error. These measurement methods are suitable for vapor temperature at dozens of degrees. The fitting function for the experimental data of 87Rb atomic density is given. Project supported by the Natural Science Foundation of China (Grant Nos. 11274118 and 11474095), the Innovation Program of Shanghai Municipal Education Commission of China (Grant No. 13ZZ036), and the Fundamental Research Funds for the Central Universities of China.

Circuit Board Analysis for Lead by Atomic Absorption Spectroscopy in a Course for Nonscience Majors

ERIC Educational Resources Information Center

Weidenhammer, Jeffrey D.

2007-01-01

A circuit board analysis of the atomic absorption spectroscopy, which is used to measure lead content in a course for nonscience majors, is being presented. The experiment can also be used to explain the potential environmental hazards of unsafe disposal of various used electronic equipments.

Bismuth as a general internal standard for lead in atomic absorption spectrometry.

PubMed

Bechlin, Marcos A; Fortunato, Felipe M; Ferreira, Edilene C; Gomes Neto, José A; Nóbrega, Joaquim A; Donati, George L; Jones, Bradley T

2014-06-11

Bismuth was evaluated as internal standard for Pb determination by line source flame atomic absorption spectrometry (LS FAAS), high-resolution continuum source flame atomic absorption spectrometry (HR-CS FAAS) and line source graphite furnace atomic absorption spectrometry (LS GFAAS). Analysis of samples containing different matrices indicated close relationship between Pb and Bi absorbances. Correlation coefficients of calibration curves built up by plotting A(Pb)/A(Bi)versus Pb concentration were higher than 0.9953 (FAAS) and higher than 0.9993 (GFAAS). Recoveries of Pb improved from 52-118% (without IS) to 97-109% (IS, LS FAAS); 74-231% (without IS) to 96-109% (IS, HR-CS FAAS); and 36-125% (without IS) to 96-110% (IS, LS GFAAS). The relative standard deviations (n=12) were reduced from 0.6-9.2% (without IS) to 0.3-4.3% (IS, LS FAAS); 0.7-7.7% (without IS) to 0.1-4.0% (IS, HR-CS FAAS); and 2.1-13% (without IS) to 0.4-5.9% (IS, LS GFAAS). Copyright © 2014 Elsevier B.V. All rights reserved.

Transition metal atomic multiplets in the ligand K-edge x-ray absorption spectra and multiple oxidation states in the L2,3 emission of strongly correlated compounds

NASA Astrophysics Data System (ADS)

Jiménez-Mier, J.; Olalde-Velasco, P.; Yang, W.-L.; Denlinger, J.

2014-07-01

We present results that show that atomic multiplet ligand field calculations are in very good agreement with experimental x-ray absorption spectra at the L2,3 edge of transition metal (TM) di-fluorides (MF2, MCrCu). For chromium more than one TM oxidation state is needed to achieve such an agreement. We also show that signature of the TM atomic multiplet can be found at the pre-edge of the fluorine K-edge x-ray absorption spectra. TM atomic multiplet ligand field calculations with a structureless core hole show good agreement with the observed pre-edges in the experimental fluorine absorption spectra. Preliminary results for the comparison between calculated and experimental resonant x-ray emission spectra for nominal CrF2 with more than one oxidation state indicate the presence of three chromium oxidation states in the bulk.

Remote laser evaporative molecular absorption spectroscopy

NASA Astrophysics Data System (ADS)

Hughes, Gary B.; Lubin, Philip; Cohen, Alexander; Madajian, Jonathan; Kulkarni, Neeraj; Zhang, Qicheng; Griswold, Janelle; Brashears, Travis

2016-09-01

We describe a novel method for probing bulk molecular and atomic composition of solid targets from a distant vantage. A laser is used to melt and vaporize a spot on the target. With sufficient flux, the spot temperature rises rapidly, and evaporation of surface materials occurs. The melted spot creates a high-temperature blackbody source, and ejected material creates a plume of surface materials in front of the spot. Molecular and atomic absorption occurs as the blackbody radiation passes through the ejected plume. Bulk molecular and atomic composition of the surface material is investigated by using a spectrometer to view the heated spot through the ejected plume. The proposed method is distinct from current stand-off approaches to composition analysis, such as Laser-Induced Breakdown Spectroscopy (LIBS), which atomizes and ionizes target material and observes emission spectra to determine bulk atomic composition. Initial simulations of absorption profiles with laser heating show great promise for Remote Laser-Evaporative Molecular Absorption (R-LEMA) spectroscopy. The method is well-suited for exploration of cold solar system targets—asteroids, comets, planets, moons—such as from a spacecraft orbiting the target. Spatial composition maps could be created by scanning the surface. Applying the beam to a single spot continuously produces a borehole or trench, and shallow subsurface composition profiling is possible. This paper describes system concepts for implementing the proposed method to probe the bulk molecular composition of an asteroid from an orbiting spacecraft, including laser array, photovoltaic power, heating and ablation, plume characteristics, absorption, spectrometry and data management.

VUV absorption spectroscopy measurements of the role of fast neutral atoms in high-power gap breakdown

DOE Office of Scientific and Technical Information (OSTI.GOV)

FILUK,A.B.; BAILEY,JAMES E.; CUNEO,MICHAEL E.

The maximum power achieved in a wide variety of high-power devices, including electron and ion diodes, z pinches, and microwave generators, is presently limited by anode-cathode gap breakdown. A frequently-discussed hypothesis for this effect is ionization of fast neutral atoms injected throughout the anode-cathode gap during the power pulse. The authors describe a newly-developed diagnostic tool that provides the first direct test of this hypothesis. Time-resolved vacuum-ultraviolet absorption spectroscopy is used to directly probe fast neutral atoms with 1 mm spatial resolution in the 10 mm anode-cathode gap of the SABRE 5 MV, 1 TW applied-B ion diode. Absorption spectramore » collected during Ar RF glow discharges and with CO{sub 2} gas fills confirm the reliability of the diagnostic technique. Throughout the 50--100 ns ion diode pulses no measurable neutral absorption is seen, setting upper limits of 0.12--1.5 x 10{sup 14} cm{sup {minus}3} for ground state fast neutral atom densities of H, C, N, O, F. The absence of molecular absorption bands also sets upper limits of 0.16--1.2 x 10{sup 15} cm{sup {minus}3} for common simple molecules. These limits are low enough to rule out ionization throughout the gap as a breakdown mechanism. This technique can now be applied to quantify the role of neutral atoms in other high-power devices.« less

Infrared absorption nano-spectroscopy using sample photoexpansion induced by tunable quantum cascade lasers.

PubMed

Lu, Feng; Belkin, Mikhail A

2011-10-10

We report a simple technique that allows obtaining mid-infrared absorption spectra with nanoscale spatial resolution under low-power illumination from tunable quantum cascade lasers. Light absorption is detected by measuring associated sample thermal expansion with an atomic force microscope. To detect minute thermal expansion we tune the repetition frequency of laser pulses in resonance with the mechanical frequency of the atomic force microscope cantilever. Spatial resolution of better than 50 nm is experimentally demonstrated.

Low loss liquid crystal photonic bandgap fiber in the near-infrared region

NASA Astrophysics Data System (ADS)

Scolari, Lara; Wei, Lei; Gauza, Sebastian; Wu, Shin-Tson; Bjarklev, Anders

2011-01-01

We infiltrate a perdeuterated liquid crystal with a reduced infrared absorption in a photonic crystal fiber. The H atoms of this liquid crystal were substituted with D atoms in order to move the vibration bands which cause absorption loss to longer wavelengths and therefore reduce the absorption in the spectral range of 1-2 μm. We achieve in the middle of the near-infrared transmission bandgap the lowest loss (about 1 dB) ever reported for this kind of devices.

Selective determination of arsenic(III) and arsenic(V) with ammonium pyrrolidinedithiocarbamate, sodium diethyldithiocarbamate and dithizone by means of flameless atomic-absorption spectrophotometry with a carbon-tube atomizer.

PubMed

Kamada, T

The extraction behaviour of arsenic(III) and arsenic(V) with ammonium pyrrolidinedithiocarbamate, sodium diethyldithiocarbamate and dithizone in organic solvents has been investigated by means of nameless atomic-absorption spectrophotometry with a carbon-tube atomizer. The selective extraction of arsenic(III) and differential determination of arsenic(III) and arsenic(V) have been developed. With ammonium pyrrolidinedithiocarbamate and methyl isobutyl ketone or nitrobenzene, when the aqueous phase/solvent volume ratio is 5 and the injection volume in the carbon tube is 20 mul, the sensitivities for 1% absorption are 0.4 and 0.5 part per milliard of arsenic, respectively. The relative standard deviations are ca. 3%. Interference by many metal ions can be prevented by masking with EDTA. The proposed methods are applied satisfactorily for determination of As(III) and As(V) in various types of water.

Cold atomic hydrogen in the inner galaxy

NASA Technical Reports Server (NTRS)

Dickey, J. M.; Garwood, R. W.

1986-01-01

The VLA is used to measure 21 cm absorption in directions with the absolute value of b less than 1 deg., the absolute value of 1 less than 25 deg. to probe the cool atomic gas in the inner galaxy. Abundant H I absorption is detected; typical lines are deep and narrow, sometimes blending in velocity with adjacent features. Unlike 21 cm emission not all allowed velocities are covered: large portions of the l-v diagram are optically thin. Although not similar to H I emission, the absorption shows a striking correspondence with CO emission in the inner galaxy: essentially every strong feature detected in one survey is seen in the other. The provisional conclusion is that in the inner galaxy most cool atomic gas is associated with molecular cloud complexes. There are few or no cold atomic clouds devoid of molecules in the inner galaxy, although these are common in the outer galaxy.

X-ray absorption spectroscopic studies of the active sites of nickel- and copper-containing metalloproteins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, Grace O.

1993-06-01

X-ray absorption spectroscopy (XAS) is a useful tool for obtaining structural and chemical information about the active sites of metalloproteins and metalloenzymes. Information may be obtained from both the edge region and the extended X-ray absorption fine structure (EXAFS) or post-edge region of the K-edge X-ray absorption spectrum of a metal center in a compound. The edge contains information about the valence electronic structure of the atom that absorbs the X-rays. It is possible in some systems to infer the redox state of the metal atom in question, as well as the geometry and nature of ligands connected to it,more » from the features in the edge in a straightforward manner. The EXAFS modulations, being produced by the backscattering of the ejected photoelectron from the atoms surrounding the metal atom, provide, when analyzed, information about the number and type of neighbouring atoms, and the distances at which they occur. In this thesis, analysis of both the edge and EXAFS regions has been used to gain information about the active sites of various metalloproteins. The metalloproteins studied were plastocyanin (Pc), laccase and nickel carbon monoxide dehydrogenase (Ni CODH). Studies of Cu(I)-imidazole compounds, related to the protein hemocyanin, are also reported here.« less

Material impacts and heat flux characterization of an electrothermal plasma source with an applied magnetic field

NASA Astrophysics Data System (ADS)

Gebhart, T. E.; Martinez-Rodriguez, R. A.; Baylor, L. R.; Rapp, J.; Winfrey, A. L.

2017-08-01

To produce a realistic tokamak-like plasma environment in linear plasma device, a transient source is needed to deliver heat and particle fluxes similar to those seen in an edge localized mode (ELM). ELMs in future large tokamaks will deliver heat fluxes of ˜1 GW/m2 to the divertor plasma facing components at a few Hz. An electrothermal plasma source can deliver heat fluxes of this magnitude. These sources operate in an ablative arc regime which is driven by a DC capacitive discharge. An electrothermal source was configured with two pulse lengths and tested under a solenoidal magnetic field to determine the resulting impact on liner ablation, plasma parameters, and delivered heat flux. The arc travels through and ablates a boron nitride liner and strikes a tungsten plate. The tungsten target plate is analyzed for surface damage using a scanning electron microscope.

1.65 mm diameter forward-viewing confocal endomicroscopic catheter using a flip-chip bonded electrothermal MEMS fiber scanner.

PubMed

Seo, Yeong-Hyeon; Hwang, Kyungmin; Jeong, Ki-Hun

2018-02-19

We report a 1.65 mm diameter forward-viewing confocal endomicroscopic catheter using a flip-chip bonded electrothermal MEMS fiber scanner. Lissajous scanning was implemented by the electrothermal MEMS fiber scanner. The Lissajous scanned MEMS fiber scanner was precisely fabricated to facilitate flip-chip connection, and bonded with a printed circuit board. The scanner was successfully combined with a fiber-based confocal imaging system. A two-dimensional reflectance image of the metal pattern 'OPTICS' was successfully obtained with the scanner. The flip-chip bonded scanner minimizes electrical packaging dimensions. The inner diameter of the flip-chip bonded MEMS fiber scanner is 1.3 mm. The flip-chip bonded MEMS fiber scanner is fully packaged with a 1.65 mm diameter housing tube, 1 mm diameter GRIN lens, and a single mode optical fiber. The packaged confocal endomicroscopic catheter can provide a new breakthrough for diverse in-vivo endomicroscopic applications.

Electrothermal enrichment of submicron particles in an insulator-based dielectrophoretic microdevice.

PubMed

Kale, Akshay; Song, Le; Lu, Xinyu; Yu, Liandong; Hu, Guoqing; Xuan, Xiangchun

2018-03-01

Insulator-based dielectrophoresis (iDEP) exploits in-channel hurdles and posts etc. to create electric field gradients for various particle manipulations. However, the presence of such insulating structures also amplifies the Joule heating in the fluid around themselves, leading to both temperature gradients and electrothermal flow. These Joule heating effects have been previously demonstrated to weaken the dielectrophoretic focusing and trapping of microscale and nanoscale particles. We find that the electrothermal flow vortices are able to entrain submicron particles for a localized enrichment near the insulating tips of a ratchet microchannel. This increase in particle concentration is reasonably predicted by a full-scale numerical simulation of the mass transport along with the coupled charge, heat and fluid transport. Our model also predicts the electric current and flow pattern in the fluid with a good agreement with the experimental observations. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design and characterization of a microelectromechanical system electro-thermal linear motor with interlock mechanism for micro manipulators.

PubMed

Hu, Tengjiang; Zhao, Yulong; Li, Xiuyuan; Zhao, You; Bai, Yingwei

2016-03-01

The design, fabrication, and testing of a novel electro-thermal linear motor for micro manipulators is presented in this paper. The V-shape electro-thermal actuator arrays, micro lever, micro spring, and slider are introduced. In moving operation, the linear motor can move nearly 1 mm displacement with 100 μm each step while keeping the applied voltage as low as 17 V. In holding operation, the motor can stay in one particular position without consuming energy and no creep deformation is found. Actuation force of 12.7 mN indicates the high force generation capability of the device. Experiments of lifetime show that the device can wear over two million cycles of operation. A silicon-on-insulator wafer is introduced to fabricate a high aspect ratio structure and the chip size is 8.5 mm × 8.5 mm × 0.5 mm.

NASA electrothermal auxiliary propulsion technology

NASA Technical Reports Server (NTRS)

Stone, J. R.

1986-01-01

Electrothermal auxiliary propulsion systems provide high performance options which can have major mission benefits. There are several electrothermal concepts which offer a range of characteristics and benefits. Resistojets are the highest thrust to power option and are currently operational at mission average values of specific impulse, I sub sp approximately 295 sec. Long life, multipropellant resistojets are being developed for the space station, and resistojet technology advancements are being pursued to improve the I sub sp by more than 20 percent for resistojets used in satellite applications. Direct current arcjets have the potential of I sub sp over 400 sec with storable propellants and should provide over 1000 sec with hydrogen. Advanced concepts are being investigated to provide high power density options and possible growth to primary propulsion applications. Broad based experimental and analytical research and technology programs of NASA are summarized and recent significant advances are reviewed.

Intradiscal electrothermal therapy used to manage chronic discogenic low back pain: new directions and interventions.

PubMed

Wetzel, F Todd; McNally, Thomas A; Phillips, Frank M

2002-11-15

Retrospective literature review. To review the data on the clinical efficacy of intradiscal electrothermal annuloplasty found at this writing in the peer-reviewed literature to date, to discuss the methodologic strengths and flaws of the studies, to discuss the pitfalls of clinical study designs, to emphasize the need for prospective randomized studies and for increased basic science investigation. Studies published or presented at peer-reviewed societies concerning the clinical efficacy of intradiscal electrothermal annuloplasty are reviewed, including background studies on deafferentation and application of thermal energy to alter biomechanical and structural properties. A proposal for future investigations is presented. Background data from intracapsular annuloplasty highlighting the safety and efficacy of intradiscal electrothermal annuloplasty are presented. Current studies on this procedure, including those in the National Registry are reviewed. All the studies share a common study design: prospective cohort with historical or noninterventional groups used as controls. The patients reviewed are similar. All have nonradicular low back pain of at least 3 months duration, failed conservative care, normal neurologic examination, and MRI showing only nondegenerative disc disease and positive concordant discography. All the patients underwent intradiscal electrothermal annuloplasty lesion at one or two levels according to standard protocols. Follow-up evaluation was performed at various intervals up to 2 years. All the studies used data from a visual analog scale, with most using the Short Form 36 (SF-36) as outcome instruments. The reported follow-up periods for the studies ranged from 6 months to 2 years. Three published studies, one with a 6-month follow-up period and two with a 1-year follow-up period, were published in the peer-reviewed literature. Two recent reports presented to the North American Spine Society were reviewed: a study of patients on a manufacturer-sponsored registry with a 1-year follow-up period and a multicenter prospective cohort study of 75 patients in an intent-to-treat group, with a 1-year follow-up period. Using the 7-point criteria of Deyo et al, all the studies suggested a positive effect of treatment, with a decrease in visual analog scale ratings and improvement in SF-36 scales, particularly those for physical function and bodily pain. The studies published so far suggest that the pain resulting from lumbar disc disease may be diminished by intradiscal electrothermal annuloplasty. All these studies project a positive therapeutic effect. However, all the studies suffer from the same methodologic flaws. A prospective cohort design or a nonrandomized prospective design is used with a biased control. The scientific validity of various study designs is discussed, and a randomized prospective study is recommended. Additionally, more investigation into the basic science of the action of intradiscal electrothermal annuloplasty is required.

Cadmium, copper, lead, and zinc determination in precipitation: A comparison of inductively coupled plasma atomic emission spectrometry and graphite furnace atomization atomic absorption spectrometry

USGS Publications Warehouse

Reddy, M.M.; Benefiel, M.A.; Claassen, H.C.

1987-01-01

Selected trace element analysis for cadmium, copper, lead, and zinc in precipitation samples by inductively coupled plasma atomic emission Spectrometry (ICP) and by atomic absorption spectrometry with graphite furnace atomization (AAGF) have been evaluated. This task was conducted in conjunction with a longterm study of precipitation chemistry at high altitude sites located in remote areas of the southwestern United States. Coefficients of variation and recovery values were determined for a standard reference water sample for all metals examined for both techniques. At concentration levels less than 10 micrograms per liter AAGF analyses exhibited better precision and accuracy than ICP. Both methods appear to offer the potential for cost-effective analysis of trace metal ions in precipitation. ?? 1987 Springer-Verlag.

[Determination of sulfur in plant using a high-resolution continuum source atomic absorption spectrometer].

PubMed

Wang, Yu; Li, Jia-xi

2009-05-01

A method for the analysis of sulfur (S) in plant by molecular absorption of carbon monosulfide (CS) using a high-resolution continuum source atomic absorption spectrometer (CS AAS) with a fuel-rich air/acetylene flame has been devised. The strong CS absorption band was found around 258 nm. The half-widths of some absorption bands were of the order of picometers, the same as the common atomic absorption lines. The experimental procedure in this study provided optimized instrumental conditions (the ratio of acetylene to air, the burner height) and parameters, and researched the spectral interferences and chemical interferences. The influence of the organic solvents on the CS absorption signals and the different digestion procedures for the determination of sulfur were also investigated. The limit of detection achieved for sulfur was 14 mg x L(-1), using the CS wavelength of 257. 961 nm and a measurement time of 3 s. The accuracy and precision were verified by analysis of two plant standard reference materials. The major applications of this method have been used for the determination of sulfur in plant materials, such as leaves. Compared to the others, this method for the analysis of sulfur is rapid, easy and simple for sulfur determination in plant.

Microwave absorption properties of carbon nanocoils coated with highly controlled magnetic materials by atomic layer deposition.

PubMed

Wang, Guizhen; Gao, Zhe; Tang, Shiwei; Chen, Chaoqiu; Duan, Feifei; Zhao, Shichao; Lin, Shiwei; Feng, Yuhong; Zhou, Lei; Qin, Yong

2012-12-21

In this work, atomic layer deposition is applied to coat carbon nanocoils with magnetic Fe(3)O(4) or Ni. The coatings have a uniform and highly controlled thickness. The coated nanocoils with coaxial multilayer nanostructures exhibit remarkably improved microwave absorption properties compared to the pristine carbon nanocoils. The enhanced absorption ability arises from the efficient complementarity between complex permittivity and permeability, chiral morphology, and multilayer structure of the products. This method can be extended to exploit other composite materials benefiting from its convenient control of the impedance matching and combination of dielectric-magnetic multiple loss mechanisms for microwave absorption applications.

Fundamental Studies on Donor-acceptor Conjugated Polymers Containing 'Heavy' Group 14 and Group 16 Elements

NASA Astrophysics Data System (ADS)

Gibson, Gregory Laird

One advantage of conjugated polymers as organic materials is that their properties may be readily tuned through covalent modifications. This thesis presents studies on the structure-property relationships resulting from single- and double-atom substitutions on an alternating donor-acceptor conjugated polymer. Specifically, single selenium and tellurium atoms have been incorporated into the acceptor monomer in place of sulfur; silicon and germanium atoms have been substituted in place of carbon at the donor monomer bridge position. The carbon-donor/ tellurium-acceptor polymer was synthesized by a post-polymerization reaction sequence and demonstrated the utility of heavy group 16 atoms to red shift a polymer absorption spectrum. Density functional theory calculations point to a new explanation for this result invoking the lower heavy atom ionization energy and reduced aromaticity of acceptor monomers containing selenium and tellurium compared to sulfur. Absorption and emission experiments demonstrate that both silicon and germanium substitutions in the donor slightly blue shift the polymer absorption spectrum. Polymers containing sulfur in the acceptor are the strongest light absorbers of all polymers studied here. Molecular weight and phenyl end capping studies show that molecular weight appears to affect polymer absorption to the greatest degree in a medium molecular weight regime and that these effects have a significant aggregation component. Solar cell devices containing either the silicon- or germanium-donor/selenium-acceptor polymer display improved red light harvesting or hole mobility relative to their structural analogues. Overall, these results clarify the effects of single atom substitution on donor-acceptor polymers and aid in the future design of polymers containing heavy atoms.

Overcoming Matrix Effects in a Complex Sample: Analysis of Multiple Elements in Multivitamins by Atomic Absorption Spectroscopy

ERIC Educational Resources Information Center

Arnold, Randy J.; Arndt, Brett; Blaser, Emilia; Blosser, Chris; Caulton, Dana; Chung, Won Sog; Fiorenza, Garrett; Heath, Wyatt; Jacobs, Alex; Kahng, Eunice; Koh, Eun; Le, Thao; Mandla, Kyle; McCory, Chelsey; Newman, Laura; Pithadia, Amit; Reckelhoff, Anna; Rheinhardt, Joseph; Skljarevski, Sonja; Stuart, Jordyn; Taylor, Cassie; Thomas, Scott; Tse, Kyle; Wall, Rachel; Warkentien, Chad

2011-01-01

A multivitamin tablet and liquid are analyzed for the elements calcium, magnesium, iron, zinc, copper, and manganese using atomic absorption spectrometry. Linear calibration and standard addition are used for all elements except calcium, allowing for an estimate of the matrix effects encountered for this complex sample. Sample preparation using…

A Simplified Digestion Protocol for the Analysis of Hg in Fish by Cold Vapor Atomic Absorption Spectroscopy

ERIC Educational Resources Information Center

Kristian, Kathleen E.; Friedbauer, Scott; Kabashi, Donika; Ferencz, Kristen M.; Barajas, Jennifer C.; O'Brien, Kelly

2015-01-01

Analysis of mercury in fish is an interesting problem with the potential to motivate students in chemistry laboratory courses. The recommended method for mercury analysis in fish is cold vapor atomic absorption spectroscopy (CVAAS), which requires homogeneous analyte solutions, typically prepared by acid digestion. Previously published digestion…

Improved hopcalite procedure for the determination of mercury vapor in air by flameless atomic absorption.

PubMed

Rathje, A O; Marcero, D H

1976-05-01

Mercury vapor is efficiently trapped from air by passage through a small glass tube filled with hopcalite. The hopcalite and adsorbed mercury are dissolved in a mixture of nitric and hydrochloric acids. Solution is rapid and complete, with no loss of mercury. Analysis is completed by flameless atomic absorption.

Interstellar photoelectric absorption cross sections, 0.03-10 keV

NASA Technical Reports Server (NTRS)

Morrison, R.; Mccammon, D.

1983-01-01

An effective absorption cross section per hydrogen atom has been calculated as a function of energy in the 0.03-10 keV range using the most recent atomic cross section and cosmic abundance data. Coefficients of a piecewise polynomial fit to the numerical results are given to allow convenient application in automated calculations.

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of antimony by automated-hydride atomic absorption spectrophotometry

USGS Publications Warehouse

Brown, G.E.; McLain, B.J.

1994-01-01

The analysis of natural-water samples for antimony by automated-hydride atomic absorption spectrophotometry is described. Samples are prepared for analysis by addition of potassium and hydrochloric acid followed by an autoclave digestion. After the digestion, potassium iodide and sodium borohydride are added automatically. Antimony hydride (stibine) gas is generated, then swept into a heated quartz cell for determination of antimony by atomic absorption spectrophotometry. Precision and accuracy data are presented. Results obtained on standard reference water samples agree with means established by interlaboratory studies. Spike recoveries for actual samples range from 90 to 114 percent. Replicate analyses of water samples of varying matrices give relative standard deviations from 3 to 10 percent.

Numerical investigation of the electric field distribution and the power deposition in the resonant cavity of a microwave electrothermal thruster

NASA Astrophysics Data System (ADS)

Yildiz, Mehmet Serhan; Celik, Murat

2017-04-01

Microwave electrothermal thruster (MET), an in-space propulsion concept, uses an electromagnetic resonant cavity as a heating chamber. In a MET system, electromagnetic energy is converted to thermal energy via a free floating plasma inside a resonant cavity. To optimize the power deposition inside the cavity, the factors that affect the electric field distribution and the resonance conditions must be accounted for. For MET thrusters, the length of the cavity, the dielectric plate that separates the plasma zone from the antenna, the antenna length and the formation of a free floating plasma have direct effects on the electromagnetic wave transmission and thus the power deposition. MET systems can be tuned by adjusting the lengths of the cavity or the antenna. This study presents the results of a 2-D axis symmetric model for the investigation of the effects of cavity length, antenna length, separation plate thickness, as well as the presence of free floating plasma on the power absorption. Specifically, electric field distribution inside the resonant cavity is calculated for a prototype MET system developed at the Bogazici University Space Technologies Laboratory. Simulations are conducted for a cavity fed with a constant power input of 1 kW at 2.45 GHz using COMSOL Multiphysics commercial software. Calculations are performed for maximum plasma electron densities ranging from 1019 to 1021 #/m3. It is determined that the optimum antenna length changes with changing plasma density. The calculations show that over 95% of the delivered power can be deposited to the plasma when the system is tuned by adjusting the cavity length.

An Unusual Strong Visible-Light Absorption Band in Red Anatase TiO2 Photocatalyst Induced by Atomic Hydrogen-Occupied Oxygen Vacancies.

PubMed

Yang, Yongqiang; Yin, Li-Chang; Gong, Yue; Niu, Ping; Wang, Jian-Qiang; Gu, Lin; Chen, Xingqiu; Liu, Gang; Wang, Lianzhou; Cheng, Hui-Ming

2018-02-01

Increasing visible light absorption of classic wide-bandgap photocatalysts like TiO 2 has long been pursued in order to promote solar energy conversion. Modulating the composition and/or stoichiometry of these photocatalysts is essential to narrow their bandgap for a strong visible-light absorption band. However, the bands obtained so far normally suffer from a low absorbance and/or narrow range. Herein, in contrast to the common tail-like absorption band in hydrogen-free oxygen-deficient TiO 2 , an unusual strong absorption band spanning the full spectrum of visible light is achieved in anatase TiO 2 by intentionally introducing atomic hydrogen-mediated oxygen vacancies. Combining experimental characterizations with theoretical calculations reveals the excitation of a new subvalence band associated with atomic hydrogen filled oxygen vacancies as the origin of such band, which subsequently leads to active photo-electrochemical water oxidation under visible light. These findings could provide a powerful way of tailoring wide-bandgap semiconductors to fully capture solar light. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simple method for determination of selenium in biological materials by flameless atomic-absorption spectrometry using a carbon-tube atomizer.

PubMed

Ishizaki, M

1978-03-01

A method for determination of selenium in biological materials by flameless atomic-absorption spectrometry using a carbon-tube atomizer is described. The sample is burned by an oxygen-flask combustion procedure, the resulting solution is treated with a cation-exchange resin to eliminate interfering cations, the selenium is extracted with dithizone in carbon tetrachloride and the resulting selenium dithizonate is combined with nickel nitrate in the carbon tube to enhance the sensitivity for selenium and avoid volatilization losses. The method measures selenium concentrations as low as 0.01 mug/g with a relative standard deviation of 8%.

Mesoporous Silica Nanoparticles as an Adsorbent for Preconcentration and Determination of Trace Amount of Nickel in Environmental Samples by Atom Trap Flame Atomic Absorption Spectrometry

NASA Astrophysics Data System (ADS)

Shirkhanloo, H.; Falahnejad, M.; Zavvar Mousavi, H.

2016-01-01

A rapid enrichment method based on solid-phase extraction (SPE) has been established for preconcentration and separation of trace Ni(II) ions in water samples prior to their determination by atom trap flame atomic absorption spectrometry. A column filled with bulky NH2-UVM7 was used as the novel adsorbent. Under optimal conditions, the linear range, limit of detection (LOD), and preconcentration factor (PF) were 3-92 μg/L, 0.8 μg/L, and 100, respectively. The validity of the method was checked by the standard reference material.

Theoretical study of Ag doping-induced vacancies defects in armchair graphene

NASA Astrophysics Data System (ADS)

Benchallal, L.; Haffad, S.; Lamiri, L.; Boubenider, F.; Zitoune, H.; Kahouadji, B.; Samah, M.

2018-06-01

We have performed a density functional theory (DFT) study of the absorption of silver atoms (Ag,Ag2 and Ag3) in graphene using SIESTA code, in the generalized gradient approximation (GGA). The absorption energy, geometry, magnetic moments and charge transfer of Ag clusters-graphene system are calculated. The minimum energy configuration demonstrates that all structures remain planar and silver atoms fit into this plane. The charge transfer between the silver clusters and carbon atoms constituting the graphene surface is an indicative of a strong bond. The structure doped with a single silver atom has a magnetic moment and the two other are nonmagnetic.

Theoretical nozzle performance of a microwave electrothermal thruster using experimental data

NASA Technical Reports Server (NTRS)

Haraburda, Scott S.; Hawley, Martin C.

1992-01-01

Research aimed at developing a fundamental understanding of the plasma processes as applied to spacecraft propulsion is presented. Calorimetric, photographic, and spectrophotometric measurements based on the TM011 and TM012 modes in the resonance cavity have been performed. The efficiency of a thruster has been calculated using a theoretical model for predicting temperature, velocity, and species density within the propellant. It is concluded that the microwave electrothermal thruster is a viable alternative to electrode thrusters.

Dynamic behavior of ultra large graphene-based membranes using electrothermal transduction

NASA Astrophysics Data System (ADS)

Al-mashaal, A. K.; Wood, G. S.; Torin, A.; Mastropaolo, E.; Newton, M. J.; Cheung, R.

2017-12-01

This letter reports an experimental study of an electrothermal actuator made from an ultra-large graphene-based bilayer thin film with a diameter to thickness aspect ratio of ˜10 000. Suspended thin films consisting of multilayer graphene and 350-500 nm-thick Poly(methyl methacrylate) have been transferred over circular cavities with a diameter of 3.5 mm. The use of bilayer materials with different mechanical and thermal properties results in thin film structures that can be induced to vibrate mechanically under the electrothermal transduction mechanism. The dynamic response of the bilayer has been investigated electrothermally by driving the structures with a combination of alternating current and direct current actuation voltages ( Va c and Vd c) and characterizing their resonant frequencies. It has been found that the bilayer thin film structure behaves as a membrane. In addition, the actuation configurations affect not only the amplitude of vibration but also the tuning of the resonant frequency of the vibrating membranes. The existence of Joule heating-induced tension lowers the mechanical stiffness of the membrane and hence shifts the resonant frequency downwards by -108187 ppm. A resonant frequency of 3.26 kHz with a vibration amplitude of 4.34 nm has been achieved for 350 nm-thick membranes under actuation voltages of 1 V of Va c and 8 V of Vd c.

A novel alternating current multiple array electrothermal micropump for lab-on-a-chip applications.

PubMed

Salari, A; Navi, M; Dalton, C

2015-01-01

The AC electrothermal technique is very promising for biofluid micropumping, due to its ability to pump high conductivity fluids. However, compared to electroosmotic micropumps, a lack of high fluid flow is a disadvantage. In this paper, a novel AC multiple array electrothermal (MAET) micropump, utilizing multiple microelectrode arrays placed on the side-walls of the fluidic channel of the micropump, is introduced. Asymmetric coplanar microelectrodes are placed on all sides of the microfluidic channel, and are actuated in different phases: one, two opposing, two adjacent, three, or all sides at the same time. Micropumps with different combinations of side electrodes and cross sections are numerically investigated in this paper. The effect of the governing parameters with respect to thermal, fluidic, and electrical properties are studied and discussed. To verify the simulations, the AC MAET concept was then fabricated and experimentally tested. The resulted fluid flow achieved by the experiments showed good agreement with the corresponding simulations. The number of side electrode arrays and the actuation patterns were also found to greatly influence the micropump performance. This study shows that the new multiple array electrothermal micropump design can be used in a wide range of applications such as drug delivery and lab-on-a-chip, where high flow rate and high precision micropumping devices for high conductivity fluids are needed.

Electrothermal feedback in kinetic inductance detectors

NASA Astrophysics Data System (ADS)

Guruswamy, T.; Thomas, C. N.; Withington, S.; Goldie, D. J.

2017-06-01

In kinetic inductance detectors (KIDs) and other similar applications of superconducting microresonators, both the large and small-signal behaviour of the device may be affected by electrothermal feedback. Microwave power applied to read out the device is absorbed by and heats the superconductor quasiparticles, changing the superconductor conductivity and hence the readout power absorbed in a positive or negative feedback loop. In this work, we explore numerically the implications of an extensible theoretical model of a generic superconducting microresonator device for a typical KID, incorporating recent work on the power flow between superconductor quasiparticles and phonons. This model calculates the large-signal (changes in operating point) and small-signal behaviour of a device, allowing us to determine the effect of electrothermal feedback on device responsivity and noise characteristics under various operating conditions. We also investigate how thermally isolating the device from the bath, for example by designing the device on a membrane only connected to the bulk substrate by thin legs, affects device performance. We find that at a typical device operating point, positive electrothermal feedback reduces the effective thermal conductance from the superconductor quasiparticles to the bath, and so increases responsivity to signal (pair-breaking) power, increases noise from temperature fluctuations, and decreases the noise equivalent power (NEP). Similarly, increasing the thermal isolation of the device while keeping the quasiparticle temperature constant decreases the NEP, but also decreases the device response bandwidth.

Observing random walks of atoms in buffer gas through resonant light absorption

NASA Astrophysics Data System (ADS)

Aoki, Kenichiro; Mitsui, Takahisa

2016-07-01

Using resonant light absorption, random-walk motions of rubidium atoms in nitrogen buffer gas are observed directly. The transmitted light intensity through atomic vapor is measured, and its spectrum is obtained, down to orders of magnitude below the shot-noise level to detect fluctuations caused by atomic motions. To understand the measured spectra, the spectrum for atoms performing random walks in a Gaussian light beam is computed, and its analytical form is obtained. The spectrum has 1 /f2 (f is frequency) behavior at higher frequencies, crossing over to a different, but well-defined, behavior at lower frequencies. The properties of this theoretical spectrum agree excellently with the measured spectrum. This understanding also enables us to obtain the diffusion constant, the photon cross section of atoms in buffer gas, and the atomic number density from a single spectral measurement. We further discuss other possible applications of our experimental method and analysis.

Dynamical Evolution of Properties for Atom and Field in the Process of Two-Photon Absorption and Emission Between Atomic Levels

NASA Astrophysics Data System (ADS)

Wang, Jian-ming; Xu, Xue-xiang

2018-04-01

Using dressed state method, we cleverly solve the dynamics of atom-field interaction in the process of two-photon absorption and emission between atomic levels. Here we suppose that the atom is initially in the ground state and the optical field is initially in Fock state, coherent state or thermal state, respectively. The properties of the atom, including the population in excited state and ground state, the atom inversion, and the properties for optical field, including the photon number distribution, the mean photon number, the second-order correlation function and the Wigner function, are discussed in detail. We derive their analytical expressions and then make numerical analysis for them. In contrast with Jaynes-Cummings model, some similar results, such as quantum Rabi oscillation, revival and collapse, are also exhibit in our considered model. Besides, some novel nonclassical states are generated.

Excitation of atoms and ions in plasmas by ultra-short electromagnetic pulses

NASA Astrophysics Data System (ADS)

Astapenko, V. A.; Sakhno, S. V.; Svita, S. Yu; Lisitsa, V. S.

2017-02-01

The problem of atoms and ions diagnostics in rarefied and dense plasmas by ultrashort laser pulses (USP) is under consideration. The application of USP provides: 1) excitation from ground states due to their carrier frequency high enough, 2) penetration into optically dense media due to short pulses duration. The excitation from ground atomic states increases sharply populations of excited atomic states in contrast with standard laser induced fluorescence spectroscopy based on radiative transitions between excited atomic states. New broadening parameter in radiation absorption, namely inverse pulse duration time 1/τ appears in addition to standard line-shape width in the profile G(ω). The Lyman-beta absorption spectra for USP are calculated for Holtsmark static broadening mechanism. Excitation of highly charged H-like ions in hot plasmas is described by both Gaussian shapes for Doppler broadening and pulse spectrum resulting in analytical absorption line-shape. USP penetration into optically thick media and corresponding excitation probability are calculated. It is shown a great effect of USP duration on excitation probabilities in optically thick media. The typical situations for plasma diagnostics by USP are discussed in details.

Strong-field two-photon transition by phase shaping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, Sangkyung; Lim, Jongseok; Ahn, Jaewook

2010-08-15

We demonstrate the ultrafast coherent control of a nonlinear two-photon absorption in a dynamically shifted energy level structure. We use a spectrotemporal laser-pulse shaping that is programed to preserve the resonant absorption condition during the intense laser-field interaction. Experiments carried out in the strong-field regime of two-photon absorption in the ground state of atomic cesium reveal that the analytically obtained offset and curvature of a laser spectrum compensate the effect of both static and dynamic energy shifts of the given light-atom interaction.

Developing a Transdisciplinary Teaching Implement for Atomic Absorption Spectroscopy

ERIC Educational Resources Information Center

Drew, John

2008-01-01

In this article I explain why I wrote the set of teaching notes on Atomic Absorption Spectroscopy (AAS) and why they look the way they do. The notes were intended as a student reference to question, highlight and write over as much as they wish during an initial practical demonstration of the threshold concept being introduced, in this case…

Assessing the Engagement, Learning, and Overall Experience of Students Operating an Atomic Absorption Spectrophotometer with Remote Access Technology

ERIC Educational Resources Information Center

Erasmus, Daniel J.; Brewer, Sharon E.; Cinel, Bruno

2015-01-01

The use of internet-based technologies in the teaching of laboratories has emerged as a promising education tool. This study evaluated the effectiveness of using remote access technology to operate an atomic absorption spectrophotometer in analyzing the iron content in a crude myoglobin extract. Sixty-two students were surveyed on their level of…

The Use of a Microprocessor-Controlled, Video Output Atomic Absorption Spectrometer as an Educational Tool in a Two-Year Technical Curriculum.

ERIC Educational Resources Information Center

Kerfoot, Henry B.

Based on instructional experiences at Charles County Community College, Maryland, this report examines the pedagogical advantage of teaching atomic absorption (AA) spectroscopy with an AA spectrophotometer that is equipped with a microprocessor and video output mechanism. The report first discusses the growing importance of AA spectroscopy in…

The DTIC Review: Volume 2, Number 4, Surviving Chemical and Biological Warfare

DTIC Science & Technology

1996-12-01

CHROMATOGRAPHIC ANALYSIS, NUCLEAR MAGNETIC RESONANCE, INFRARED SPECTROSCOPY , ARMY RESEARCH, DEGRADATION, VERIFICATION, MASS SPECTROSCOPY , LIQUID... mycotoxins . Such materials are not attractive as weapons of mass destruction however, as large amounts are required to produce lethal effects. In...VERIFICATION, ATOMIC ABSORPTION SPECTROSCOPY , ATOMIC ABSORPTION. AL The DTIC Review Defense Technical Information Center AD-A285 242 AD-A283 754 EDGEWOOO

NHEXAS PHASE I ARIZONA STUDY--STANDARD OPERATING PROCEDURE FOR OPERATION, CALIBRATION AND MAINTENANCE OF THE PERKIN-ELMER 1100B ATOMIC ABSORPTION SPECTROMETER (BCO-L-5.1)

EPA Science Inventory

The purpose of this SOP is to outline the start-up, calibration, operation, and maintenance procedures for the Perkin-Elmer 5100 PC Atomic Absorption Spectrophotometer (PE 5100). These procedures are used for the determination of the target trace metal, as in soil, house dust, f...

Facilities Management Guide for Asbestos and Lead

DTIC Science & Technology

2004-11-01

equipment such as HEPA filtered power tools, portable welding exhaust systems, and paint removal equipment when work disturbs lead. Do not dry sweep ...sampling and analysis of [______] paint bulk and wipe samples by atomic absorption spectrophotometry (AA) or anodic stripping voltametry (ASV...analysis. e. All bulk (destructive) collected for lead shall be analyzed by atomic absorption spectrophotometry (AA) or anodic stripping voltametry

Micro-sampling method based on high-resolution continuum source graphite furnace atomic absorption spectrometry for calcium determination in blood and mitochondrial suspensions.

PubMed

Gómez-Nieto, Beatriz; Gismera, Mª Jesús; Sevilla, Mª Teresa; Satrústegui, Jorgina; Procopio, Jesús R

2017-08-01

A micro-sampling and straightforward method based on high resolution continuum source atomic absorption spectrometry (HR-CS AAS) was developed to determine extracellular and intracellular Ca in samples of interest in clinical and biomedical analysis. Solid sampling platforms were used to introduce the micro-samples into the graphite furnace atomizer. The secondary absorption line for Ca, located at 239.856nm, was selected to carry out the measurements. Experimental parameters such as pyrolysis and atomization temperatures and the amount of sample introduced for the measurements were optimized. Calibration was performed using aqueous standards and the approach to measure at the wings of the absorption lines was employed for the expansion of the linear response range. The limit of detection was of 0.02mgL -1 Ca (0.39ng Ca) and the upper limit of linear range was increased up to 8.0mgL -1 Ca (160ng Ca). The proposed method was used to determine Ca in mitochondrial suspensions and whole blood samples with successful results. Adequate recoveries (within 91-107%) were obtained in the tests performed for validation purposes. Copyright © 2017 Elsevier B.V. All rights reserved.

Vaginal cuff thermal injury by mode of colpotomy at total laparoscopic hysterectomy: a randomized clinical trial.

PubMed

Teoh, Deanna; Lowery, William J; Jiang, Xiaoyin; Ehrisman, Jessie; Halvorson, Paige; Broadwater, Gloria; Bentley, Rex; Secord, Angeles Alvarez; Sobolewski, Craig; Berchuck, Andrew; Havrilesky, Laura J; Valea, Fidel A; Lee, Paula S

2015-02-01

To evaluate if the use of Valleylab mode ("V mode") (Covidien, Mansfield, MA) electrothermal energy for colpotomy during total laparoscopic hysterectomy (LH) results in a smaller margin of thermal injury to the upper vagina compared with traditional cut/coagulate (cut/coag) electrothermal energy. Prospective randomized clinical trial (Canadian Task Force classification I). University medical center. A total of 101 subjects who underwent LH between June 2010 and August 2012. Subjects were randomized to colpotomy by V mode electrothermal energy or cut/coag electrothermal energy. The primary end point was the median depth of thermal injury measured in millimeters. The secondary end points included the proportion of subjects who developed granulation tissue, induration, infection, or dehiscence at the vaginal cuff at 4 weeks, 3 months, or 6 months postoperatively. There was no significant difference in the median depth of thermal injury in the cut/coag and V mode arms (anterior margin: 0.68 mm vs 0.63 mm [p = .94], posterior margin: 0.66 mm vs 0.70 mm [p = .87], respectively). Twenty-seven percent of subjects in each arm developed at least 1 of the clinical end points at 4 weeks, 3 months, or 6 months postoperatively (granulation tissue: 6%-18% vs 8%-21%, induration: 0%-2% vs 4%-5%, infection: 0%-4% vs 0%-10%, dehiscence: 2% vs 0% in the cut/coag and V mode arms, respectively), with no difference between arms (p = 1.0). The V mode does not reduce the depth of thermal injury compared with cut/coag electrothermal energy when used for colpotomy incision during total laparoscopic hysterectomy (Clinical Trials.gov ID: NCT02080546). Copyright © 2015 AAGL. Published by Elsevier Inc. All rights reserved.

Fluorescence detection of white-beam X-ray absorption anisotropy: towards element-sensitive projections of local atomic structure

PubMed Central

Korecki, P.; Tolkiehn, M.; Dąbrowski, K. M.; Novikov, D. V.

2011-01-01

Projections of the atomic structure around Nb atoms in a LiNbO3 single crystal were obtained from a white-beam X-ray absorption anisotropy (XAA) pattern detected using Nb K fluorescence. This kind of anisotropy results from the interference of X-rays inside a sample and, owing to the short coherence length of a white beam, is visible only at small angles around interatomic directions. Consequently, the main features of the recorded XAA corresponded to distorted real-space projections of dense-packed atomic planes and atomic rows. A quantitative analysis of XAA was carried out using a wavelet transform and allowed well resolved projections of Nb atoms to be obtained up to distances of 10 Å. The signal of nearest O atoms was detected indirectly by a comparison with model calculations. The measurement of white-beam XAA using characteristic radiation indicates the possibility of obtaining element-sensitive projections of the local atomic structure in more complex samples. PMID:21997909

Electromagnetically induced transparency and nonlinear pulse propagation in a combined tripod and Λ atom-light coupling scheme

NASA Astrophysics Data System (ADS)

Hamedi, H. R.; Ruseckas, J.; Juzeliūnas, G.

2017-09-01

We consider propagation of a probe pulse in an atomic medium characterized by a combined tripod and Lambda (Λ) atom-light coupling scheme. The scheme involves three atomic ground states coupled to two excited states by five light fields. It is demonstrated that dark states can be formed for such an atom-light coupling. This is essential for formation of the electromagnetically induced transparency (EIT) and slow light. In the limiting cases the scheme reduces to conventional Λ- or N-type atom-light couplings providing the EIT or absorption, respectively. Thus, the atomic system can experience a transition from the EIT to the absorption by changing the amplitudes or phases of control lasers. Subsequently the scheme is employed to analyze the nonlinear pulse propagation using the coupled Maxwell-Bloch equations. It is shown that a generation of stable slow light optical solitons is possible in such a five-level combined tripod and Λ atomic system.

Parameterization and Validation of an Integrated Electro-Thermal LFP Battery Model

DTIC Science & Technology

2012-01-01

integrated electro- thermal model for an A123 26650 LiFePO4 battery is presented. The electrical dynamics of the cell are described by an equivalent...the parameterization of an integrated electro-thermal model for an A123 26650 LiFePO4 battery is presented. The electrical dynamics of the cell are...the average of the charge and discharge curves taken at very low current (C/20), since the LiFePO4 cell chemistry is known to yield a hysteresis effect

First-principles calculations of K-shell X-ray absorption spectra for warm dense nitrogen

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Zi; Zhang, Shen; Kang, Wei

2016-05-15

X-ray absorption spectrum is a powerful tool for atomic structure detection on warm dense matter. Here, we perform first-principles molecular dynamics and X-ray absorption spectrum calculations on warm dense nitrogen along a Hugoniot curve. From the molecular dynamics trajectory, the detailed atomic structures are examined for each thermodynamical condition. The K-shell X-ray absorption spectrum is calculated, and its changes with temperature and pressure along the Hugoniot curve are discussed. The warm dense nitrogen systems may contain isolated nitrogen atoms, N{sub 2} molecules, and nitrogen clusters, which show quite different contributions to the total X-ray spectrum due to their different electronmore » density of states. The changes of X-ray spectrum along the Hugoniot curve are caused by the different nitrogen structures induced by the temperature and the pressure. Some clear signatures on X-ray spectrum for different thermodynamical conditions are pointed out, which may provide useful data for future X-ray experiments.« less

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory; determination of chromium in water by graphite furnace atomic absorption spectrophotometry

USGS Publications Warehouse

McLain, B.J.

1993-01-01

Graphite furnace atomic absorption spectrophotometry is a sensitive, precise, and accurate method for the determination of chromium in natural water samples. The detection limit for this analytical method is 0.4 microg/L with a working linear limit of 25.0 microg/L. The precision at the detection limit ranges from 20 to 57 percent relative standard deviation (RSD) with an improvement to 4.6 percent RSD for concentrations more than 3 microg/L. Accuracy of this method was determined for a variety of reference standards that was representative of the analytical range. The results were within the established standard deviations. Samples were spiked with known concentrations of chromium with recoveries ranging from 84 to 122 percent. In addition, a comparison of data between graphite furnace atomic absorption spectrophotometry and direct-current plasma atomic emission spectrometry resulted in suitable agreement between the two methods, with an average deviation of +/- 2.0 microg/L throughout the analytical range.

Evolution in time of an N-atom system. I. A physical basis set for the projection of the master equation

NASA Astrophysics Data System (ADS)

Freedhoff, Helen

2004-01-01

We study an aggregate of N identical two-level atoms (TLA’s) coupled by the retarded interatomic interaction, using the Lehmberg-Agarwal master equation. First, we calculate the entangled eigenstates of the system; then, we use these eigenstates as a basis set for the projection of the master equation. We demonstrate that in this basis the equations of motion for the level populations, as well as the expressions for the emission and absorption spectra, assume a simple mathematical structure and allow for a transparent physical interpretation. To illustrate the use of the general theory in emission processes, we study an isosceles triangle of atoms, and present in the long wavelength limit the (cascade) emission spectrum for a hexagon of atoms fully excited at t=0. To illustrate its use for absorption processes, we tabulate (in the same limit) the biexciton absorption frequencies, linewidths, and relative intensities for polygons consisting of N=2,…,9 TLA’s.

Determination of selected elements in whole coal and in coal ash from the eight argonne premium coal samples by atomic absorption spectrometry, atomic emission spectrometry, and ion-selective electrode

USGS Publications Warehouse

Doughten, M.W.; Gillison, J.R.

1990-01-01

Methods for the determination of 24 elements in whole coal and coal ash by inductively coupled argon plasma-atomic emission spectrometry, flame, graphite furnace, and cold vapor atomic absorption spectrometry, and by ion-selective electrode are described. Coal ashes were analyzed in triplicate to determine the precision of the methods. Results of the analyses of NBS Standard Reference Materials 1633, 1633a, 1632a, and 1635 are reported. Accuracy of the methods is determined by comparison of the analysis of standard reference materials to their certified values as well as other values in the literature.

Two-photon absorption laser-induced fluorescence measurements of atomic nitrogen in a radio-frequency atmospheric-pressure plasma jet

NASA Astrophysics Data System (ADS)

Wagenaars, E.; Gans, T.; O'Connell, D.; Niemi, K.

2012-08-01

The first direct measurements of atomic nitrogen species in a radio-frequency atmospheric-pressure plasma jet (APPJ) are presented. Atomic nitrogen radicals play a key role in new plasma medicine applications of APPJs. The measurements were performed with a two-photon absorption laser-induced fluorescence diagnostic, using 206.65 nm laser photons for the excitation of ground-state N atoms and observing fluorescence light around 744 nm. The APPJ was run with a helium gas flow of 1 slm and varying small admixtures of molecular nitrogen of 0-0.7 vol%. A maximum in the measured N concentration was observed for an admixture of 0.25 vol% N2.

First-principles studies of a photovoltaic material based on silicon heavily codoped with sulfur and nitrogen

NASA Astrophysics Data System (ADS)

Dong, Xiao; Wang, Yongyong; Song, Xiaohui; Yang, Feng

2018-03-01

In silicon co-hyperdoped with nitrogen and sulfur, dopant atoms tend to form dimers in the near-equilibrium process. The dimer that contains substitutional N and S atoms has the lowest formation energy and can form an impurity band that overlaps with the conduction band (CB). When separating the two atoms far apart from each other, the impurity band is clearly isolated from the CB and becomes an intermediate band (IB). The sub-band-gap absorption decreases with the decrease in the substitutional atom distance. The sub-band-gap absorption of the material is the combined effect of the configurations with different N-S distances.

Production mechanism of atomic nitrogen in atmospheric pressure pulsed corona discharge measured using two-photon absorption laser-induced fluorescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Teramoto, Yoshiyuki; Ono, Ryo; Oda, Tetsuji

To study the production mechanism of atomic nitrogen, the temporal profile and spatial distribution of atomic nitrogen are measured in atmospheric pressure pulsed positive corona discharge using two-photon absorption laser-induced fluorescence. The absolute atomic nitrogen density in the streamer filaments is estimated from decay rate of atomic nitrogen in N{sub 2} discharge. The results indicate that the absolute atomic nitrogen density is approximately constant against discharge energy. When the discharge voltage is 21.5 kV, production yield of atomic nitrogen produced by an N{sub 2} discharge pulse is estimated to be 2.9 - 9.8 Multiplication-Sign 10{sup 13} atoms and the energymore » efficiency of atomic nitrogen production is estimated to be about 1.8 - 6.1 Multiplication-Sign 10{sup 16} atoms/J. The energy efficiency of atomic nitrogen production in N{sub 2} discharge is constant against the discharge energy, while that in N{sub 2}/O{sub 2} discharge increases with discharge energy. In the N{sub 2}/O{sub 2} discharge, two-step process of N{sub 2} dissociation plays significant role for atomic nitrogen production.« less

U.S.-MEXICO BORDER PROGRAM ARIZONA BORDER STUDY--STANDARD OPERATING PROCEDURE FOR OPERATION, CALIBRATION, AND MAINTENANCE OF THE PERKIN-ELMER 5100 PC ATOMIC ABSORPTION SPECTROMETER (BCO-L-5.1)

EPA Science Inventory

The purpose of this SOP is to outline the start-up, calibration, operation, and maintenance procedures for the Perkin-Elmer 5100 PC Atomic Absorption Spectrophotometer (PE 5100). These procedures are used for the determination of the target trace metal, as in soil, house dust, f...

Analysis of an Air Conditioning Coolant Solution for Metal Contamination Using Atomic Absorption Spectroscopy: An Undergraduate Instrumental Analysis Exercise Simulating an Industrial Assignment

ERIC Educational Resources Information Center

Baird, Michael J.

2004-01-01

A real-life analytical assignment is presented to students, who had to examine an air conditioning coolant solution for metal contamination using an atomic absorption spectroscopy (AAS). This hands-on access to a real problem exposed the undergraduate students to the mechanism of AAS, and promoted participation in a simulated industrial activity.

Determination of Pb in Biological Samples by Graphite Furnace Atomic Absorption Spectrophotometry: An Exercise in Common Interferences and Fundamental Practices in Trace Element Determination

ERIC Educational Resources Information Center

Spudich, Thomas M.; Herrmann, Jennifer K.; Fietkau, Ronald; Edwards, Grant A.

2004-01-01

An experiment is conducted to ascertain trace-level Pb in samples of bovine liver or muscle by applying graphite furnace atomic absorption spectrophotometry (GFAAS). The primary objective is to display the effects of physical and spectral intrusions in determining trace elements, and project the usual methods employed to minimize accuracy errors…

Correlation between Wavelength Dispersive X-ray Fluorescence (WDXRF) analysis of hardened concrete for chlorides vs. Atomic Absorption (AA) analysis in accordance with AASHTO T- 260; sampling and testing for chloride ion in concrete and concrete raw mater

DOT National Transportation Integrated Search

2014-04-01

A correlation between Wavelength Dispersive X-ray Fluorescence(WDXRF) analysis of Hardened : Concrete for Chlorides and Atomic Absorption (AA) analysis (current method AASHTO T-260, procedure B) has been : found and a new method of analysis has been ...

Identifying Student and Teacher Difficulties in Interpreting Atomic Spectra Using a Quantum Model of Emission and Absorption of Radiation

ERIC Educational Resources Information Center

Savall-Alemany, Francisco; Domènech-Blanco, Josep Lluís; Guisasola, Jenaro; Martínez-Torregrosa, Joaquín

2016-01-01

Our study sets out to identify the difficulties that high school students, teachers, and university students encounter when trying to explain atomic spectra. To do so, we identify the key concepts that any quantum model for the emission and absorption of electromagnetic radiation must include to account for the gas spectra and we then design two…

Determination of Fe Content of Some Food Items by Flame Atomic Absorption Spectroscopy (FAAS): A Guided-Inquiry Learning Experience in Instrumental Analysis Laboratory

ERIC Educational Resources Information Center

Fakayode, Sayo O.; King, Angela G.; Yakubu, Mamudu; Mohammed, Abdul K.; Pollard, David A.

2012-01-01

This article presents a guided-inquiry (GI) hands-on determination of Fe in food samples including plantains, spinach, lima beans, oatmeal, Frosted Flakes cereal (generic), tilapia fish, and chicken using flame atomic absorption spectroscopy (FAAS). The utility of the GI experiment, which is part of an instrumental analysis laboratory course,…

Infrared reduction, an efficient method to control the non-linear optical property of graphene oxide in femtosecond regime

NASA Astrophysics Data System (ADS)

Bhattacharya, S.; Maiti, R.; Saha, S.; Das, A. C.; Mondal, S.; Ray, S. K.; Bhaktha, S. B. N.; Datta, P. K.

2016-04-01

Graphene Oxide (GO) has been prepared by modified Hummers method and it has been reduced using an IR bulb (800-2000 nm). Both as grown GO and reduced graphene oxide (RGO) have been characterized using Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). Raman spectra shows well documented Dband and G-band for both the samples while blue shift of G-band confirms chemical functionalization of graphene with different oxygen functional group. The XPS result shows that the as-prepared GO contains 52% of sp2 hybridized carbon due to the C=C bonds and 33% of carbon atoms due to the C-O bonds. As for RGO, increment of the atomic % of the sp2 hybridized carbon atom to 83% and rapid decrease in atomic % of C=O bonds confirm an efficient reduction with infrared radiation. UV-Visible absorption spectrum also confirms increment of conjugation with increased reduction. Non-linear optical properties of both GO and RGO are measured using single beam open aperture Z-Scan technique in femtosecond regime. Intensity dependent nonlinear phenomena are observed. Depending upon the intensity, both saturable absorption and two photon absorption contribute to the non-linearity of both the samples. Saturation dominates at low intensity (~ 127 GW/cm2) while two photon absorption become prominent at higher intensities (from 217 GW/cm2 to 302 GW/cm2). We have calculated the two-photon absorption co-efficient and saturation intensity for both the samples. The value of two photon absorption co-efficient (for GO~ 0.0022-0.0037 cm/GW and for RGO~ 0.0128-0.0143 cm/GW) and the saturation intensity (for GO~57 GW/cm2 and for RGO~ 194GW/cm2) is increased with reduction. Increase in two photon absorption coefficient with increasing intensity can also suggest that there may be multi-photon absorption is taking place.

Fabrication and Characterization of Novel Electrothermal Self-Healing Microcapsules with Graphene/Polymer Hybrid Shells for Bitumenious Material.

PubMed

Wang, Xinyu; Guo, Yandong; Su, Junfeng; Zhang, Xiaolong; Wang, Yingyuan; Tan, Yiqiu

2018-06-09

Self-healing bituminous material has been a hot research topic in self-healing materials, and this smart self-healing approach is a promising a revolution in pavement material technology. Bitumen has a self-healing naturality relating to temperature, healing time, and aging degree. To date, heat induction and microencapsulation rejuvenator are two feasible approaches, which have been put into real applications. However, both methods have disadvantages limiting their practical results and efficiency. It will be an ideal method combining the advantages and avoiding the disadvantages of the above two methods at the same time. The aim of this work was to synthesize and characterize electrothermal self-healing microcapsules containing bituminous rejuvenator with graphene/organic nanohybrid structure shells. The microcapsules owned electric conductivity capability because of the advent of graphene, and realized the self-healing through the two approaches of heat induction and rejuvenation. The microcapsule shells were fabricated using a strength hexamethoxymethylmelamine (HMMM) resin and graphene by two-step hybrid polymerization. Experimental tests were carried out to character the morphology, integrity, and shell structure. It was found that the electric charge balance determined the graphene/HMMM microstructure. The graphene content in shells could not be greatly increased under an electrostatic balance in emulsion. X-ray photoelectron spectroscopy (XPS), Energy dispersive spectrometer (EDS), Transmission electron microscope (TEM) and Atomic force microscopy (AFM) results indicated that the graphene had deposited on shells. TGA/DTG tests implied that the thermal decomposition temperature of microcapsules with graphene had increased to about 350 °C. The thermal conductivity of microcapsules had been sharply increased to about 8.0 W/m²·K with 2.0 wt % graphene in shells. At the same time, electrical resistivity of microcapsules/bitumen samples had a decrease with more graphene in bitumen.

A coupled electro-thermal Discontinuous Galerkin method

NASA Astrophysics Data System (ADS)

Homsi, L.; Geuzaine, C.; Noels, L.

2017-11-01

This paper presents a Discontinuous Galerkin scheme in order to solve the nonlinear elliptic partial differential equations of coupled electro-thermal problems. In this paper we discuss the fundamental equations for the transport of electricity and heat, in terms of macroscopic variables such as temperature and electric potential. A fully coupled nonlinear weak formulation for electro-thermal problems is developed based on continuum mechanics equations expressed in terms of energetically conjugated pair of fluxes and fields gradients. The weak form can thus be formulated as a Discontinuous Galerkin method. The existence and uniqueness of the weak form solution are proved. The numerical properties of the nonlinear elliptic problems i.e., consistency and stability, are demonstrated under specific conditions, i.e. use of high enough stabilization parameter and at least quadratic polynomial approximations. Moreover the prior error estimates in the H1-norm and in the L2-norm are shown to be optimal in the mesh size with the polynomial approximation degree.

Modeling Microscale Electro-thermally Induced Vortex Flows

NASA Astrophysics Data System (ADS)

Paul, Rajorshi; Tang, Tian; Kumar, Aloke

2017-11-01

In presence of a high frequency alternating electric field and a laser induced heat source, vortex flows are generated inside micro-channels. Such electro-thermally influenced micro-vortices can be used for manipulating nano-particles, programming colloidal assemblies, trapping biological cells as well as for fabricating designed bacterial biofilms. In this study, a theoretical model is developed for microscale electro-thermally induced vortex flows with multiple heat sources. Semi-analytical solutions are obtained, using Hankel transformation and linear superposition, for the temperature, pressure and velocity fields. The effect of material properties such as electrical and thermal conductivities, as well as experimental parameters such as the frequency and strength of the alternating electric field, and the intensity and heating profile of the laser source, are systematically investigated. Resolution for a pair of laser sources is determined by analyzing the strength of the micro-vortices under the influence of two heating sources. Results from this work will provide useful insights into the design of efficient optical tweezers and Rapid Electrokinetic Patterning techniques.

Material impacts and heat flux characterization of an electrothermal plasma source with an applied magnetic field

DOE PAGES

Gebhart, T. E.; Martinez-Rodriguez, R. A.; Baylor, L. R.; ...

2017-08-11

To produce a realistic tokamak-like plasma environment in linear plasma device, a transient source is needed to deliver heat and particle fluxes similar to those seen in an edge localized mode (ELM). ELMs in future large tokamaks will deliver heat fluxes of ~1 GW/m 2 to the divertor plasma facing components at a few Hz. An electrothermal plasma source can deliver heat fluxes of this magnitude. These sources operate in an ablative arc regime which is driven by a DC capacitive discharge. An electrothermal source was configured in this paper with two pulse lengths and tested under a solenoidal magneticmore » field to determine the resulting impact on liner ablation, plasma parameters, and delivered heat flux. The arc travels through and ablates a boron nitride liner and strikes a tungsten plate. Finally, the tungsten target plate is analyzed for surface damage using a scanning electron microscope.« less

Material impacts and heat flux characterization of an electrothermal plasma source with an applied magnetic field

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gebhart, T. E.; Martinez-Rodriguez, R. A.; Baylor, L. R.

To produce a realistic tokamak-like plasma environment in linear plasma device, a transient source is needed to deliver heat and particle fluxes similar to those seen in an edge localized mode (ELM). ELMs in future large tokamaks will deliver heat fluxes of ~1 GW/m 2 to the divertor plasma facing components at a few Hz. An electrothermal plasma source can deliver heat fluxes of this magnitude. These sources operate in an ablative arc regime which is driven by a DC capacitive discharge. An electrothermal source was configured in this paper with two pulse lengths and tested under a solenoidal magneticmore » field to determine the resulting impact on liner ablation, plasma parameters, and delivered heat flux. The arc travels through and ablates a boron nitride liner and strikes a tungsten plate. Finally, the tungsten target plate is analyzed for surface damage using a scanning electron microscope.« less

Determination of Cd in urine by cloud point extraction-tungsten coil atomic absorption spectrometry.

PubMed

Donati, George L; Pharr, Kathryn E; Calloway, Clifton P; Nóbrega, Joaquim A; Jones, Bradley T

2008-09-15

Cadmium concentrations in human urine are typically at or below the 1 microgL(-1) level, so only a handful of techniques may be appropriate for this application. These include sophisticated methods such as graphite furnace atomic absorption spectrometry and inductively coupled plasma mass spectrometry. While tungsten coil atomic absorption spectrometry is a simpler and less expensive technique, its practical detection limits often prohibit the detection of Cd in normal urine samples. In addition, the nature of the urine matrix often necessitates accurate background correction techniques, which would add expense and complexity to the tungsten coil instrument. This manuscript describes a cloud point extraction method that reduces matrix interference while preconcentrating Cd by a factor of 15. Ammonium pyrrolidinedithiocarbamate and Triton X-114 are used as complexing agent and surfactant, respectively, in the extraction procedure. Triton X-114 forms an extractant coacervate surfactant-rich phase that is denser than water, so the aqueous supernatant is easily removed leaving the metal-containing surfactant layer intact. A 25 microL aliquot of this preconcentrated sample is placed directly onto the tungsten coil for analysis. The cloud point extraction procedure allows for simple background correction based either on the measurement of absorption at a nearby wavelength, or measurement of absorption at a time in the atomization step immediately prior to the onset of the Cd signal. Seven human urine samples are analyzed by this technique and the results are compared to those found by the inductively coupled plasma mass spectrometry analysis of the same samples performed at a different institution. The limit of detection for Cd in urine is 5 ngL(-1) for cloud point extraction tungsten coil atomic absorption spectrometry. The accuracy of the method is determined with a standard reference material (toxic metals in freeze-dried urine) and the determined values agree with the reported levels at the 95% confidence level.

Absorption cross sections of some atmospheric molecules for resonantly scattered O I 1304-A radiation

NASA Technical Reports Server (NTRS)

Starr, W. L.

1976-01-01

Absorption cross sections for O2, N2, CO2, CH4, N2O, and CO have been measured at each of the lines of the atomic oxygen triplet at 1302, 1305, and 1306 A. Radiation resonantly scattered from oxygen atoms at a temperature of about 300 K was used for the line source. Absorber temperatures were also near 300 K. Direct application of the Lambert-Beer absorption equation yielded pressure-dependent cross sections for carbon monoxide at each line of the O I triplet. Reasons for this apparent dependence are presented and discussed.

Direct sampling graphite furnace atomic absorption spectrometry - feasibility of Na and K determination in desalted crude oil

NASA Astrophysics Data System (ADS)

Seeger, Tassia S.; Machado, Eduarda Q.; Flores, Erico M. M.; Mello, Paola A.; Duarte, Fabio A.

2018-03-01

In this study, Na and K were determined in desalted crude oil by direct sampling graphite furnace atomic absorption spectrometry (DS-GF AAS), with the use of a Zeeman-effect background correction system with variable magnetic field. The analysis was performed in low and high sensitivity conditions. Sodium determination was performed in two low-sensitivity conditions: 1) main absorption line (589.0 nm), gas stop flow during the atomization step and 3-field dynamic mode (0.6-0.8 T); and 2) secondary absorption line (330.3 nm), gas stop flow during the atomization and 2-field mode (0.8 T). In K determination, some parameters, such as high-sensitivity mode, main absorption line (766.5 nm), gas stop flow during the atomization and 2-field mode (0.8 T), were used. Suitability of chemical modifiers, such as Pd and W-Ir was also evaluated. The heating program for Na and K was based on the pyrolysis and atomization curves. Calibration was performed by aqueous standards. Accuracy was evaluated by the analysis of Green Petroleum Coke (SRM NIST 2718) and Trace Elements in Fuel Oil (SRM NIST 1634c). Recovery tests were also performed and results were compared with those obtained by GF AAS after crude oil digestion by microwave-assisted digestion. The characteristic mass of Na was 17.1 pg and 0.46 ng in conditions 1 and 2, respectively, while the one of K was 1.4 pg. Limits of detection and quantification by DS-GF AAS were 30 and 40 ng g-1 for Na and 3.2 and 4.2 ng g-1 for K, respectively. Sodium and K were determined in three crude oil samples with API density ranging from 20.9 to 28.0. Sodium and K concentration ranged from 1.5 to 73 μg g-1 and from 23 to 522 ng g-1, respectively.

Determination of tetraalkyllead compounds in gasoline by liquid chromatography-atomic absorption spectrometry

USGS Publications Warehouse

Messman, J.D.; Rains, T.C.

1981-01-01

A liquid chromatography-atomic absorption spectrometry (LC-AAS) hybrid analytical technique is presented for metal speciation measurements on complex liquid samples. The versatility and inherent metal selectivity of the technique are Illustrated by the rapid determination of five tetraalkyllead compounds in commercial gasoline. Separation of the individual tetraalkyllead species is achieved by reversed-phase liquid chromatography using an acetonitrile/water mobile phase. The effluent from the liquid Chromatograph Is introduced directly into the aspiration uptake capillary of the nebulizer of an air/acetylene flame atomic absorption spectrometer. Spectral interferences due to coeluting hydrocarbon matrix constituents were not observed at the 283.3-nm resonance line of lead used for analysis. Detection limits of this LC-AAS hydrid analytical technique, based on a 20-??L injection, are approximately 10 ng Pb for each tetraalkyllead compound.

Mass energy-absorption coefficients and average atomic energy-absorption cross-sections for amino acids in the energy range 0.122-1.330 MeV

DOE Office of Scientific and Technical Information (OSTI.GOV)

More, Chaitali V., E-mail: chaitalimore89@gmail.com; Lokhande, Rajkumar M.; Pawar, Pravina P., E-mail: pravinapawar4@gmail.com

Mass attenuation coefficients of amino acids such as n-acetyl-l-tryptophan, n-acetyl-l-tyrosine and d-tryptophan were measured in the energy range 0.122-1.330 MeV. NaI (Tl) scintillation detection system was used to detect gamma rays with a resolution of 8.2% at 0.662 MeV. The measured attenuation coefficient values were then used to determine the mass energy-absorption coefficients (σ{sub a,en}) and average atomic energy-absorption cross sections (μ{sub en}/ρ) of the amino acids. Theoretical values were calculated based on XCOM data. Theoretical and experimental values are found to be in good agreement.

Lithogeochemistry of mineralized and altered rock samples from the northern Talkeetna Mountains, south-central Alaska

USGS Publications Warehouse

Light, Thomas D.; Schmidt, Jeanine M.

2011-01-01

Mineralized and altered rock samples collected from the northern Talkeetna Mountains, Alaska, were analyzed by two different inductively coupled plasma atomic-emission spectrometry (ICP-AES) methods for as many as 44 elements; by fire assay and either direct-coupled plasma (DCP) or atomic absorption spectrophotometry (AAS) for gold (Au); by cold vapor atomic absorption (CVAA) for mercury (Hg); and by irradiated neutron activation analysis (INAA) for tungsten (W). The analytical results showed that some samples contain high values of multiple elements and may be potential indicators of hydrothermal mineralization in the area.

Structure of Co-Doped Alq3 thin films investigated by grazing incidence X-ray absorption fine structure and Fourier transform infrared spectroscopy.

PubMed

Lin, Liang; Pang, Zhiyong; Fang, Shaojie; Wang, Fenggong; Song, Shumei; Huang, Yuying; Wei, Xiangjun; Yu, Haisheng; Han, Shenghao

2011-02-10

The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.

Manganese dioxide causes spurious gold values in flame atomic-absorption readings from HBr-Br2 digestions

USGS Publications Warehouse

Campbell, W.L.

1981-01-01

False readings, apparently caused by the presence of high concentrations of manganese dioxide, have been observed in our current flame atomic-absorption procedure for the determination of gold. After a hydrobromic acid (HBr)-bromine (Br2) leach, simply heating the sample to boiling to remove excess Br2 prior to extraction with methyl-isobutyl-ketone (MIBK) eliminates these false readings. ?? 1981.

Rapid determination of nanogram amounts of tellurium in silicate rocks

USGS Publications Warehouse

Greenland, L.P.; Campbell, E.Y.

1976-01-01

A hydride-generation flameless atomic-absorption technique is used to determine as little as 5 ng g-1 tellurium in 0.25 g of silicate rock. After acid decomposition of the sample, tellurium hydride is generated with sodium borohydride and the vapor passed directly to a resistance-heated quartz cell mounted in an atomic-absorption spectrophotometer. Analyses of 11 U.S. Geological Survey standard rocks are presented. ?? 1976.

Attosecond XUV absorption spectroscopy of doubly excited states in helium atoms dressed by a time-delayed femtosecond infrared laser

NASA Astrophysics Data System (ADS)

Yang, Z. Q.; Ye, D. F.; Ding, Thomas; Pfeifer, Thomas; Fu, L. B.

2015-01-01

In the present paper, we investigate the time-resolved transient absorption spectroscopy of doubly excited states of helium atoms by solving the time-dependent two-electron Schrödinger equation numerically based on a one-dimensional model. The helium atoms are subjected to an extreme ultraviolet (XUV) attosecond pulse and a time-delayed infrared (IR) few-cycle laser pulse. A superposition of doubly excited states populated by the XUV pulse is identified, which interferes with the direct ionization pathway leading to Fano resonance profiles in the photoabsorption spectrum. In the presence of an IR laser, however, the Fano line profiles are strongly modified: A shifting, splitting, and broadening of the original absorption lines is observed when the XUV attosecond pulse and infrared few-cycle laser pulse overlap in time, which is in good agreement with recent experimental results. At certain time delays, we observe symmetric Lorentz, inverted Fano profiles, and even negative absorption cross sections indicating that the XUV light can be amplified during the interaction with atoms. We further prove that the above pictures are general for different doubly excited states by suitably varying the frequency of the IR field to coherently couple the corresponding states.

[Evaluation of uncertainty for determination of tin and its compounds in air of workplace by flame atomic absorption spectrometry].

PubMed

Wei, Qiuning; Wei, Yuan; Liu, Fangfang; Ding, Yalei

2015-10-01

To investigate the method for uncertainty evaluation of determination of tin and its compounds in the air of workplace by flame atomic absorption spectrometry. The national occupational health standards, GBZ/T160.28-2004 and JJF1059-1999, were used to build a mathematical model of determination of tin and its compounds in the air of workplace and to calculate the components of uncertainty. In determination of tin and its compounds in the air of workplace using flame atomic absorption spectrometry, the uncertainty for the concentration of the standard solution, atomic absorption spectrophotometer, sample digestion, parallel determination, least square fitting of the calibration curve, and sample collection was 0.436%, 0.13%, 1.07%, 1.65%, 3.05%, and 2.89%, respectively. The combined uncertainty was 9.3%.The concentration of tin in the test sample was 0.132 mg/m³, and the expanded uncertainty for the measurement was 0.012 mg/m³ (K=2). The dominant uncertainty for determination of tin and its compounds in the air of workplace comes from least squares fitting of the calibration curve and sample collection. Quality control should be improved in the process of calibration curve fitting and sample collection.

Path integral Monte Carlo study on the structure and absorption spectra of alkali atoms (Li, Na, K) attached to superfluid helium clusters

NASA Astrophysics Data System (ADS)

Nakayama, Akira; Yamashita, Koichi

2001-01-01

Path integral Monte Carlo calculations have been performed to investigate the microscopic structure and thermodynamic properties of the AkṡHeN (Ak=Li, Na, K,N⩽300) clusters at T=0.5 K. Absorption spectra which correspond to the 2P←2S transitions of alkali atoms are also calculated within a pairwise additive model, which employs diatomic Ak-He potential energy curves. The size dependences of the cluster structure and absorption spectra that show the influence of the helium cluster environment are examined in detail. It is found that alkali atoms are trapped in a dimple on the helium cluster's surface and that, from the asymptotic behavior, the AkṡHe300 cluster, at least semiquantitatively, mimics the local structure of experimentally produced large helium clusters in the vicinity of alkali atoms. We have successfully reproduced the overall shapes of the spectra and explained their features from a static and structural point of view. The positions, relative intensities, and line widths of the absorption maxima are calculated to be in moderate agreement with experiments [F. Stienkemeier, J. Higgins, C. Callegari, S. I. Kanorsky, W. E. Ernst, and G. Scoles, Z. Phys. D 38, 253 (1996)].

Tuning optical properties of magic number cluster (SiO2)4O2H4 by substitutional bonding with gold atoms.

PubMed

Cai, Xiulong; Zhang, Peng; Ma, Liuxue; Zhang, Wenxian; Ning, Xijing; Zhao, Li; Zhuang, Jun

2009-04-30

By bonding gold atoms to the magic number cluster (SiO(2))(4)O(2)H(4), two groups of Au-adsorbed shell-like clusters Au(n)(SiO(2))(4)O(2)H(4-n) (n = 1-4) and Au(n)(SiO(2))(4)O(2) (n = 5-8) were obtained, and their spectral properties were studied. The ground-state structures of these clusters were optimized by density functional theory, and the results show that in despite of the different numbers and types of the adsorbed Au atoms, the cluster core (SiO(2))(4)O(2) of T(d) point-group symmetry keeps almost unchanged. The absorption spectra were obtained by time-dependent density functional theory. From one group to the other, an extension of absorption wavelength from the UV-visible to the NIR region was observed, and in each group the absorption strengths vary linearly with the number of Au atoms. These features indicate their advantages for exploring novel materials with easily controlled tunable optical properties. Furthermore, due to the weak electronic charge transfer between the Au atoms, the clusters containing Au(2) dimers, especially Au(8)(SiO(2))(4)O(2), absorb strongly NIR light at 900 approximately 1200 nm. Such strong absorption suggests potential applications of these shell-like clusters in tumor cells thermal therapy, like the gold-coated silica nanoshells with larger sizes.

Determination of trace elements in metals and alloys by atomic-absorption spectroscopy using an induction-heated graphite well furnace as atom source.

PubMed

Headridge, J B; Smith, D R

1972-07-01

An induction-heated graphite furnace, coupled to a Unicam SP 90 atomic-absorption spectrometer, is described for the direct determination of trace elements in metals and alloys. The furnace is capable of operation at temperatures up to 2400 degrees , and has been used to obtain calibration graphs for the determination of ppm quantities of bismuth in lead-base alloys, cast irons and stainless steels, and for the determination of cadmium at the ppm level in zinc-base alloys. Milligram samples of the alloys were atomized directly. Calibration graphs for the determination of the elements in solutions were obtained for comparison. The accuracy and precision of the determination are presented and discussed.

Ly α Absorption at Transits of HD 209458b: A Comparative Study of Various Mechanisms Under Different Conditions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Khodachenko, M. L.; Lammer, H.; Kislyakova, K. G.

To shed more light on the nature of the observed Ly α absorption during transits of HD 209458b and to quantify the major mechanisms responsible for the production of fast hydrogen atoms (the so-called energetic neutral atoms, ENAs) around the planet, 2D hydrodynamic multifluid modeling of the expanding planetary upper atmosphere, which is driven by stellar XUV, and its interaction with the stellar wind has been performed. The model self-consistently describes the escaping planetary wind, taking into account the generation of ENAs due to particle acceleration by the radiation pressure and by the charge exchange between the stellar wind protonsmore » and planetary atoms. The calculations in a wide range of stellar wind parameters and XUV flux values showed that under typical Sun-like star conditions, the amount of generated ENAs is too small, and the observed absorption at the level of 6%–8% can be attributed only to the non-resonant natural line broadening. For lower XUV fluxes, e.g., during the activity minima, the number of planetary atoms that survive photoionization and give rise to ENAs increases, resulting in up to 10%–15% absorption at the blue wing of the Ly α line, caused by resonant thermal line broadening. A similar asymmetric absorption can be seen under the conditions realized during coronal mass ejections, when sufficiently high stellar wind pressure confines the escaping planetary material within a kind of bowshock around the planet. It was found that the radiation pressure in all considered cases has a negligible contribution to the production of ENAs and the corresponding absorption.« less

A low power, on demand electrothermal valve for wireless drug delivery applications

PubMed Central

Li, Po-Ying; Givrad, Tina K.; Sheybani, Roya; Holschneider, Daniel P.; Maarek, Jean-Michel I.

2014-01-01

We present a low power, on demand Parylene MEMS electrothermal valve. A novel Ω-shaped thermal resistive element requires low power (~mW) and enables rapid valve opening (~ms). Using both finite element analysis and valve opening experiments, a robust resistive element design for improved valve opening performance in water was obtained. In addition, a thermistor, as an inrush current limiter, was added into the valve circuit to provide variable current ramping. Wireless activation of the valve using RF inductive power transfer was demonstrated. PMID:20024057

Trace determination of antimony by hydride generation atomic absorption spectrometry with analyte preconcentration/atomization in a dielectric barrier discharge atomizer.

PubMed

Zurynková, Pavla; Dědina, Jiří; Kratzer, Jan

2018-06-20

Atomization conditions for antimony hydride in the plasma atomizer based on a dielectric barrier discharge (DBD) with atomic absorption spectrometric detection were optimized. Argon was found as the best discharge gas under a flow rate of 50 mL min - 1 while the DBD power was optimum at 30 W. Analytical figures of merit including interference study of As, Se and Bi have been subsequently investigated and the results compared to those found in an externally heated quartz tube atomizer (QTA). The limit of detection (LOD) reached in DBD (0.15 ng mL -1  Sb) is comparable to that observed in QTA (0.14 ng mL -1  Sb). Finally, possibility of Sb preconcentration by stibane in situ trapping in a DBD atomizer was studied. For trapping time of 300 s, the preconcentration efficiency and LOD, respectively, were 103 ± 2% and 0.02 ng mL -1 . Copyright © 2018 Elsevier B.V. All rights reserved.

Measuring Two Key Parameters of H3 Color Centers in Diamond

NASA Technical Reports Server (NTRS)

Roberts, W. Thomas

2005-01-01

A method of measuring two key parameters of H3 color centers in diamond has been created as part of a continuing effort to develop tunable, continuous-wave, visible lasers that would utilize diamond as the lasing medium. (An H3 color center in a diamond crystal lattice comprises two nitrogen atoms substituted for two carbon atoms bonded to a third carbon atom. H3 color centers can be induced artificially; they also occur naturally. If present in sufficient density, they impart a yellow hue.) The method may also be applicable to the corresponding parameters of other candidate lasing media. One of the parameters is the number density of color centers, which is needed for designing an efficient laser. The other parameter is an optical-absorption cross section, which, as explained below, is needed for determining the number density. The present method represents an improvement over prior methods in which optical-absorption measurements have been used to determine absorption cross sections or number densities. Heretofore, in order to determine a number density from such measurements, it has been necessary to know the applicable absorption cross section; alternatively, to determine the absorption cross section from such measurements, it has been necessary to know the number density. If, as in this case, both the number density and the absorption cross section are initially unknown, then it is impossible to determine either parameter in the absence of additional information.

Super-resolution atomic force photoactivated microscopy of biological samples (Conference Presentation)

NASA Astrophysics Data System (ADS)

Lee, Seunghyun; Kim, Hyemin; Shin, Seungjun; Doh, Junsang; Kim, Chulhong

2017-03-01

Optical microscopy (OM) and photoacoustic microscopy (PAM) have previously been used to image the optical absorption of intercellular features of biological cells. However, the optical diffraction limit ( 200 nm) makes it difficult for these modalities to image nanoscale inner cell structures and the distribution of internal cell components. Although super-resolution fluorescence microscopy, such as stimulated emission depletion microscopy (STED) and stochastic optical reconstruction microscopy (STORM), has successfully performed nanoscale biological imaging, these modalities require the use of exogenous fluorescence agents, which are unfavorable for biological samples. Our newly developed atomic force photoactivated microscopy (AFPM) can provide optical absorption images with nanoscale lateral resolution without any exogenous contrast agents. AFPM combines conventional atomic force microscopy (AFM) and an optical excitation system, and simultaneously provides multiple contrasts, such as the topography and magnitude of optical absorption. AFPM can detect the intrinsic optical absorption of samples with 8 nm lateral resolution, easily overcoming the diffraction limit. Using the label-free AFPM system, we have successfully imaged the optical absorption properties of a single melanoma cell (B16F10) and a rosette leaf epidermal cell of Arabidopsis (ecotype Columbia (Col-0)) with nanoscale lateral resolution. The remarkable images show the melanosome distribution of a melanoma cell and the biological structures of a plant cell. AFPM provides superior imaging of optical absorption with a nanoscale lateral resolution, and it promises to become widely used in biological and chemical research.

Focusing Light Beams To Improve Atomic-Vapor Optical Buffers

NASA Technical Reports Server (NTRS)

Strekalov, Dmitry; Matsko, Andrey; Savchenkov, Anatoliy

2010-01-01

Specially designed focusing of light beams has been proposed as a means of improving the performances of optical buffers based on cells containing hot atomic vapors (e.g., rubidium vapor). There is also a companion proposal to improve performance by use of incoherent optical pumping under suitable conditions. Regarding the proposal to use focusing: The utility of atomic-vapor optical buffers as optical storage and processing devices has been severely limited by nonuniform spatial distributions of intensity in optical beams, arising from absorption of the beams as they propagate in atomic-vapor cells. Such nonuniformity makes it impossible to optimize the physical conditions throughout a cell, thereby making it impossible to optimize the performance of the cell as an optical buffer. In practical terms simplified for the sake of brevity, "to optimize" as used here means to design the cell so as to maximize the group delay of an optical pulse while keeping the absorption and distortion of the pulse reasonably small. Regarding the proposal to use incoherent optical pumping: For reasons too complex to describe here, residual absorption of light is one of the main impediments to achievement of desirably long group delays in hot atomic vapors. The present proposal is directed toward suppressing residual absorption of light. The idea of improving the performance of slow-light optical buffers by use of incoherent pumping overlaps somewhat with the basic idea of Raman-based slow-light systems. However, prior studies of those systems did not quantitatively answer the question of whether the performance of an atomic vapor or other medium that exhibits electromagnetically induced transparency (EIT) with Raman gain is superior to that of a medium that exhibits EIT without Raman gain.

Use of multiwavelength emission from hollow cathode lamp for measurement of state resolved atom density of metal vapor produced by electron beam evaporation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Majumder, A.; Dikshit, B.; Bhatia, M. S.

2008-09-15

State resolved atom population of metal vapor having low-lying metastable states departs from equilibrium value. It needs to be experimentally investigated. This paper reports the use of hollow cathode lamp based atomic absorption spectroscopy technique to measure online the state resolved atom density (ground and metastable) of metal vapor in an atomic beam produced by a high power electron gun. In particular, the advantage of availability of multiwavelength emission in hollow cathode lamp is used to determine the atom density in different states. Here, several transitions pertaining to a given state have also been invoked to obtain the mean valuemore » of atom density thereby providing an opportunity for in situ averaging. It is observed that at higher source temperatures the atoms from metastable state relax to the ground state. This is ascribed to competing processes of atom-atom and electron-atom collisions. The formation of collision induced virtual source is inferred from measurement of atom density distribution profile along the width of the atomic beam. The total line-of-sight average atom density measured by absorption technique using hollow cathode lamp is compared to that measured by atomic vapor deposition method. The presence of collisions is further supported by determination of beaming exponent by numerically fitting the data.« less

Index of refraction engineering in five-level dressed interacting ground states atoms.

PubMed

Sagona-Stophel, Steven A; Weatherall, James Owen; Search, Christopher P

2011-08-15

We present a five-level atomic system in which the index of refraction of a probe laser can be enhanced or reduced below unity with vanishing absorption in the region between pairs of absorption and gain lines formed by dressing of the atoms with a control laser and rf/microwave fields. By weak incoherent pumping of the population into a single metastable state, one can create several narrow amplifying resonances. At frequencies between these gain lines and additional absorption lines, there exist regions of vanishing absorption but resonantly enhanced index of refraction. In Rb vapors with density N in units of cm(-3), we predict an index of refraction up to n≈√(1+1.2×10(-14)N) for the D1 line, which is more than an order of magnitude larger than other proposals for index of refraction enhancement. Furthermore, the index can be readily reduced below 1 by simply changing the sign of the probe or rf field detunings. This enhancement is robust with respect to homogeneous and inhomogeneous broadening. © 2011 Optical Society of America

Formation of nanostructures in Eu3+ doped glass-ceramics: an XAS study.

PubMed

Pellicer-Porres, J; Segura, A; Martínez-Criado, G; Rodríguez-Mendoza, U R; Lavín, V

2013-01-16

We describe the results of x-ray absorption experiments carried out to deduce structural and chemical information in Eu(3+) doped, transparent, oxyfluoride glass and nanostructured glass-ceramic samples. The spectra were measured at the Pb and Eu-L(III) edges. The Eu environment in the glass samples is observed to be similar to that of EuF(3). Complementary x-ray diffraction experiments show that thermal annealing creates β-PbF(2) type nanocrystals. X-ray absorption indicates that Eu ions act as seeds in the nanocrystal formation. There is evidence of interstitial fluorine atoms around Eu ions as well as Eu dimers. X-ray absorption at the Pb-L(III) edge shows that after the thermal treatment most lead atoms form a PbO amorphous phase and that only 10% of the lead atoms remain available to form β-PbF(2) type nanocrystals. Both x-ray diffraction and absorption point to a high Eu content in the nanocrystals. Our study suggests new approaches to the oxyfluoride glass-ceramic synthesis in order to further improve their properties.

Counterfactual Rydberg gate for photons

NASA Astrophysics Data System (ADS)

Garcia-Escartin, Juan Carlos; Chamorro-Posada, Pedro

2012-03-01

Quantum computation with photons requires efficient two-photon gates. We put forward a two-photon entangling gate which uses an intermediate atomic system. The system includes a single Rydberg atom which can switch on and off photon absorption in an ensemble using the dipole blockade. The gate is based in a counterfactual protocol. The mere possibility of an absorption that can only occur with a vanishing probability steers the photons to the desired final state.

Measurements of uranium mass confined in high density plasmas

NASA Technical Reports Server (NTRS)

Stoeffler, R. C.

1976-01-01

An X-ray absorption method for measuring the amount of uranium confined in high density, rf-heated uranium plasmas is described. A comparison of measured absorption of 8 keV X-rays with absorption calculated using Beer Law indicated that the method could be used to measure uranium densities from 3 times 10 to the 16th power atoms/cu cm to 5 times 10 to the 18th power atoms/cu cm. Tests were conducted to measure the density of uranium in an rf-heated argon plasma with UF6 infection and with the power to maintain the discharge supplied by a 1.2 MW rf induction heater facility. The uranium density was measured as the flow rate through the test chamber was varied. A maximum uranium density of 3.85 times 10 to the 17th power atoms/cu cm was measured.

[Application of atomic absorption spectrometry in the engine knock detection].

PubMed

Chen, Li-Dan

2013-02-01

Because existing human experience diagnosis method and apparatus for auxiliary diagnosis method are difficult to diagnose quickly engine knock. Atomic absorption spectrometry was used to detect the automobile engine knock in in innovative way. After having determined Fe, Al, Cu, Cr and Pb content in the 35 groups of Audi A6 engine oil whose travel course is 2 000 -70 000 kilometers and whose sampling interval is 2 000 kilometers by atomic absorption spectrometry, the database of primary metal content in the same automobile engine at different mileage was established. The research shows that the main metal content fluctuates within a certain range. In practical engineering applications, after the determination of engine oil main metal content and comparison with its database value, it can not only help to diagnose the type and location of engine knock without the disintegration and reduce vehicle maintenance costs and improve the accuracy of engine knock fault diagnosis.

Annealing induced atomic rearrangements on (Ga,In) (N,As) probed by hard X-ray photoelectron spectroscopy and X-ray absorption fine structure.

PubMed

Ishikawa, Fumitaro; Higashi, Kotaro; Fuyuno, Satoshi; Morifuji, Masato; Kondow, Masahiko; Trampert, Achim

2018-04-13

We study the effects of annealing on (Ga 0.64 ,In 0.36 ) (N 0.045 ,As 0.955 ) using hard X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements. We observed surface oxidation and termination of the N-As bond defects caused by the annealing process. Specifically, we observed a characteristic chemical shift towards lower binding energies in the photoelectron spectra related to In. This phenomenon appears to be caused by the atomic arrangement, which produces increased In-N bond configurations within the matrix, as indicated by the X-ray absorption fine structure measurements. The reduction in the binding energies of group-III In, which occurs concomitantly with the atomic rearrangements of the matrix, causes the differences in the electronic properties of the system before and after annealing.

Matrix effects on the determination of manganese in geological materials by atomic-absorption spectrophotometry under different flame conditions

USGS Publications Warehouse

Sanzolone, R.F.; Chao, T.T.

1978-01-01

Suppression caused by five of the seven matrix elements studied (Si, Al, Fe, Ca and Mg) was observed in the atomic-absorption determination of manganese in geological materials, when synthetic solutions and the recommended oxidizing air-acetylene flame were used. The magnitude of the suppression effects depends on (1) the kind and concentration of the interfering elements, (2) the type of acid medium, and (3) the concentration of manganese to be determined. All interferences noted are removed or alleviated by using a reducing nitrous oxide-acetylene flame. The atomic-absorption method using this flame can be applied to the determination of total and extractable manganese in a wide range of geological materials without interferences. Analyses of six U.S. Geological Survey rock standards for manganese gave results in agreement with the reported values. ?? 1978.

A Comprehensive X-Ray Absorption Model for Atomic Oxygen

NASA Technical Reports Server (NTRS)

Gorczyca, T. W.; Bautista, M. A.; Hasoglu, M. F.; Garcia, J.; Gatuzz, E.; Kaastra, J. S.; Kallman, T. R.; Manson, S. T.; Mendoza, C.; Raassen, A. J. J.;

Solid sampling determination of magnesium in lithium niobate crystals by graphite furnace atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Dravecz, Gabriella; Laczai, Nikoletta; Hajdara, Ivett; Bencs, László

2016-12-01

The vaporization/atomization processes of Mg in high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS-GFAAS) were investigated by evaporating solid (powder) samples of lithium niobate (LiNbO3) optical single crystals doped with various amounts of Mg in a transversally heated graphite atomizer (THGA). Optimal analytical conditions were attained by using the Mg I 215.4353 nm secondary spectral line. An optimal pyrolysis temperature of 1500 °C was found for Mg, while the compromise atomization temperature in THGAs (2400 °C) was applied for analyte vaporization. The calibration was performed against solid (powered) lithium niobate crystal standards. The standards were prepared with exactly known Mg content via solid state fusion of the oxide components of the matrix and analyte. The correlation coefficient (R value) of the linear calibration was not worse than 0.9992. The calibration curves were linear in the dopant concentration range of interest (0.74-7.25 mg/g Mg), when dosing 3-10 mg of the powder samples into the graphite sample insertion boats. The Mg content of the studied 19 samples was in the range of 1.69-4.13 mg/g. The precision of the method was better than 6.3%. The accuracy of the results was verified by means of flame atomic absorption spectrometry with solution sample introduction after digestion of several crystal samples.

Electronic theoretical study of the influences of O adsorption on the electronic structure and optical properties of graphene

NASA Astrophysics Data System (ADS)

Shuang, Zhou; Guili, Liu; Dazhi, Fan

2017-02-01

The electronic structure and optical properties of adsorbing O atoms on graphene with different O coverage are researched using the density functional theory based upon the first-principle study to obtain further insight into properties of graphene. The adsorption energies, band structures, the density of states, light absorption coefficient and reflectivity of each system are calculated theoretically after optimizing structures of each system with different O coverage. Our calculations show that adsorption of O atoms on graphene increases the bond length of C-C which adjacent to the O atoms. When the O coverage is 9.4%, the adsorption energy (3.91 eV) is the maximum, which only increases about 1.6% higher than that of 3.1% O coverage. We find that adsorbed O atoms on pristine graphene opens up indirect gap of about 0.493-0.952 eV. Adsorbing O atoms make pristine graphene from metal into a semiconductor. When the O coverage is 9.4%, the band gap (0.952 eV) is the maximum. Comparing with pristine graphene, we find the density of states at Fermi level of O atoms adsorbing on graphene with different coverage are significantly increased. We also find that light absorption coefficient and reflectivity peaks are significantly reduced, and the larger the coverage, the smaller the absorption coefficient and reflectivity peaks are. And the blue shift phenomenon appears.

Preferred site occupation of 3 d atoms in NixF e4 -xN (x =1 and 3) films revealed by x-ray absorption spectroscopy and magnetic circular dichroism

NASA Astrophysics Data System (ADS)

Takata, Fumiya; Ito, Keita; Takeda, Yukiharu; Saitoh, Yuji; Takanashi, Koki; Kimura, Akio; Suemasu, Takashi

2018-02-01

X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism measurements were performed at the Ni and Fe L2 ,3 absorption edges for N ixF e4 -xN (x =1 and 3) epitaxial films. Spectral line-shape analysis and element-specific magnetic moment evaluations are presented. Shoulders at approximately 2 eV above the Ni L2 ,3 main peaks in the XAS spectrum of N i3FeN were interpreted to originate from hybridization of orbitals between Ni 3 d at face-centered (II) sites and N 2 p at body-centered sites, while such features were missing in NiF e3N film. Similar shoulders were observed at Fe L2 ,3 edges in both films. These results indicate that the orbitals of Ni atoms did not hybridize with those of N atoms in the NiF e3N film. Hence, Ni atoms preferentially occupied corner (I) sites, where the hybridization was weak because of the relatively long distance between Ni at I sites and N atoms. The relatively large magnetic moment deduced from sum-rule analysis of NiF e3N also showed a good agreement with the presence of Ni atoms at I sites.

Atom beams split by gentle persuasion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pool, R.

1994-02-25

Two different research teams have taken a big step toward atom interferometry. They have succeeded in splitting atomic beams by using atoms in spin states that neither absorb nor reemit laser light. By proper adjustment of experimental conditions, atoms are changed from one spin state to another, without passing through the intermediary excited state. The atoms in essence absorb momentum from the laser photons, without absorption or emission of photons. The change in momentum deflects atoms in the proper spin state.

Validation of NASA Thermal Ice Protection Computer Codes. Part 1; Program Overview

NASA Technical Reports Server (NTRS)

Miller, Dean; Bond, Thomas; Sheldon, David; Wright, William; Langhals, Tammy; Al-Khalil, Kamel; Broughton, Howard

1996-01-01

The Icing Technology Branch at NASA Lewis has been involved in an effort to validate two thermal ice protection codes developed at the NASA Lewis Research Center. LEWICE/Thermal (electrothermal deicing & anti-icing), and ANTICE (hot-gas & electrothermal anti-icing). The Thermal Code Validation effort was designated as a priority during a 1994 'peer review' of the NASA Lewis Icing program, and was implemented as a cooperative effort with industry. During April 1996, the first of a series of experimental validation tests was conducted in the NASA Lewis Icing Research Tunnel(IRT). The purpose of the April 96 test was to validate the electrothermal predictive capabilities of both LEWICE/Thermal, and ANTICE. A heavily instrumented test article was designed and fabricated for this test, with the capability of simulating electrothermal de-icing and anti-icing modes of operation. Thermal measurements were then obtained over a range of test conditions, for comparison with analytical predictions. This paper will present an overview of the test, including a detailed description of: (1) the validation process; (2) test article design; (3) test matrix development; and (4) test procedures. Selected experimental results will be presented for de-icing and anti-icing modes of operation. Finally, the status of the validation effort at this point will be summarized. Detailed comparisons between analytical predictions and experimental results are contained in the following two papers: 'Validation of NASA Thermal Ice Protection Computer Codes: Part 2- The Validation of LEWICE/Thermal' and 'Validation of NASA Thermal Ice Protection Computer Codes: Part 3-The Validation of ANTICE'

Characterization of local atomic structure in Co/Zn based ZIFs by XAFS

NASA Astrophysics Data System (ADS)

Podkovyrina, Yulia; Butova, Vera; Bulanova, Elena; Budnyk, Andriy; Kremennaya, Maria; Soldatov, Alexander; Lamberti, Carlo

2018-03-01

The local atomic structure in bimetallic Co/Zn zeolitic imidazolate frameworks (ZIFs) was studied using X-ray Absorption Fine Structure (XAFS) spectroscopy and theoretical calculations. The experimental Co K-edge and Zn K-edge XANES (X-ray Absorption Near Edge Structure) spectra of Zn1-xCoxC8H10N4 samples (x = 0.05, 0.25, 0.75) synthesized by microwave synthesis were compared with the data for the ZIF-67 (x=1) and ZIF-8 (x=0). Theoretical XANES spectra for the bimetallic ZIFs were calculated. It was shown that in bimetallic ZIFs the Co and Zn atoms have the similar local environment.

A stable frequency comb directly referenced to rubidium electromagnetically induced transparency and two-photon transitions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hou, Dong; Wu, Jiutao; Zhang, Shuangyou

2014-03-17

We demonstrate an approach to create a stable erbium-fiber-based frequency comb at communication band by directly locking the combs to two rubidium atomic transitions resonances (electromagnetically induced transparency absorption and two-photon absorption), respectively. This approach directly transfers the precision and stability of the atomic transitions to the comb. With its distinguishing feature of compactness by removing the conventional octave-spanning spectrum and f-to-2f beating facilities and the ability to directly control the comb's frequency at the atomic transition frequency, this stable optical comb can be widely used in optical communication, frequency standard, and optical spectroscopy and microscopy.

Bond-length relaxation in crystalline Si1-xGex alloys: An extended x-ray-absorption fine-structure study

NASA Astrophysics Data System (ADS)

Kajiyama, Hiroshi; Muramatsu, Shin-Ichi; Shimada, Toshikazu; Nishino, Yoichi

1992-06-01

Extended x-ray-absorption fine-structure spectra for crystalline Si1-xGex alloys, measured at the K edge of Ge at room temperature, are analyzed with a curve-fitting method based on the spherical-wave approximation. The Ge-Ge and Ge-Si bond lengths, coordination numbers of Ge and Si atoms around a Ge atom, and Debye-Waller factors of Ge and Si atoms are obtained. It is shown that Ge-Ge and Ge-Si bonds relax completely, for all Ge concentrations of their study, while the lattice constant varies monotonically, following Vegard's law. As noted by Bragg and later by Pauling and Huggins, the Ge-Ge and Ge-Si bond lengths are close to the sum of their constituent-element atomic radii: nearly 2.45 Å for Ge-Ge bonds and 2.40 Å for Ge-Si bonds. A study on the coordination around a Ge atom in the alloys revealed that Ge and Si atoms mix randomly throughout the compositional range studied.

Validation of an analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals in soil

PubMed Central

2013-01-01

Background The aim of this paper was the validation of a new analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals (Ag, Cd, Co, Cr, Cu, Ni, Pb and Zn) in soil after microwave assisted digestion in aqua regia. Determinations were performed on the ContrAA 300 (Analytik Jena) air-acetylene flame spectrometer equipped with xenon short-arc lamp as a continuum radiation source for all elements, double monochromator consisting of a prism pre-monocromator and an echelle grating monochromator, and charge coupled device as detector. For validation a method-performance study was conducted involving the establishment of the analytical performance of the new method (limits of detection and quantification, precision and accuracy). Moreover, the Bland and Altman statistical method was used in analyzing the agreement between the proposed assay and inductively coupled plasma optical emission spectrometry as standardized method for the multielemental determination in soil. Results The limits of detection in soil sample (3σ criterion) in the high-resolution continuum source flame atomic absorption spectrometry method were (mg/kg): 0.18 (Ag), 0.14 (Cd), 0.36 (Co), 0.25 (Cr), 0.09 (Cu), 1.0 (Ni), 1.4 (Pb) and 0.18 (Zn), close to those in inductively coupled plasma optical emission spectrometry: 0.12 (Ag), 0.05 (Cd), 0.15 (Co), 1.4 (Cr), 0.15 (Cu), 2.5 (Ni), 2.5 (Pb) and 0.04 (Zn). Accuracy was checked by analyzing 4 certified reference materials and a good agreement for 95% confidence interval was found in both methods, with recoveries in the range of 94–106% in atomic absorption and 97–103% in optical emission. Repeatability found by analyzing real soil samples was in the range 1.6–5.2% in atomic absorption, similar with that of 1.9–6.1% in optical emission spectrometry. The Bland and Altman method showed no statistical significant difference between the two spectrometric methods for 95% confidence interval. Conclusions High-resolution continuum source flame atomic absorption spectrometry can be successfully used for the rapid, multielemental determination of hazardous/priority hazardous metals in soil with similar analytical performances to those in inductively coupled plasma optical emission spectrometry. PMID:23452327

Validation of an analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals in soil.

PubMed

Frentiu, Tiberiu; Ponta, Michaela; Hategan, Raluca

2013-03-01

The aim of this paper was the validation of a new analytical method based on the high-resolution continuum source flame atomic absorption spectrometry for the fast-sequential determination of several hazardous/priority hazardous metals (Ag, Cd, Co, Cr, Cu, Ni, Pb and Zn) in soil after microwave assisted digestion in aqua regia. Determinations were performed on the ContrAA 300 (Analytik Jena) air-acetylene flame spectrometer equipped with xenon short-arc lamp as a continuum radiation source for all elements, double monochromator consisting of a prism pre-monocromator and an echelle grating monochromator, and charge coupled device as detector. For validation a method-performance study was conducted involving the establishment of the analytical performance of the new method (limits of detection and quantification, precision and accuracy). Moreover, the Bland and Altman statistical method was used in analyzing the agreement between the proposed assay and inductively coupled plasma optical emission spectrometry as standardized method for the multielemental determination in soil. The limits of detection in soil sample (3σ criterion) in the high-resolution continuum source flame atomic absorption spectrometry method were (mg/kg): 0.18 (Ag), 0.14 (Cd), 0.36 (Co), 0.25 (Cr), 0.09 (Cu), 1.0 (Ni), 1.4 (Pb) and 0.18 (Zn), close to those in inductively coupled plasma optical emission spectrometry: 0.12 (Ag), 0.05 (Cd), 0.15 (Co), 1.4 (Cr), 0.15 (Cu), 2.5 (Ni), 2.5 (Pb) and 0.04 (Zn). Accuracy was checked by analyzing 4 certified reference materials and a good agreement for 95% confidence interval was found in both methods, with recoveries in the range of 94-106% in atomic absorption and 97-103% in optical emission. Repeatability found by analyzing real soil samples was in the range 1.6-5.2% in atomic absorption, similar with that of 1.9-6.1% in optical emission spectrometry. The Bland and Altman method showed no statistical significant difference between the two spectrometric methods for 95% confidence interval. High-resolution continuum source flame atomic absorption spectrometry can be successfully used for the rapid, multielemental determination of hazardous/priority hazardous metals in soil with similar analytical performances to those in inductively coupled plasma optical emission spectrometry.

Benefits of Low-Power Electrothermal Propulsion

NASA Technical Reports Server (NTRS)

Oleson, Steven R.; Sankovic, John M.

1997-01-01

Mission analyses were completed to show the benefits of low-power electrothermal propulsion systems for three classes'of LEO smallsat missions. Three different electrothermal systems were considered: (1) a 40 W ammonia resistojet system, (2) a 600 W hydrazine arcjet system, and (3) a 300 W ammonia resistojet. The benefits of using two 40 W ammonia resistojet systems were analyzed for three months of drag makeup of a Shuttle-launched 100 kg spacecraft in a 297 km orbit. The two 46 W resistojets decreased the propulsion system wet mass by 50% when compared to state-of-art hydrazine monopropellant thrusters. The 600 W arcjet system was used for a 300 km sun synchronous makeup mission of a 1000 kg satellite and was found to decrease the wet propulsion mass by 30%. Finally, the 300 W arcjet system was used on a 200 kg Earth-orbiting spacecraft for both orbit transfer from 300 to 400 km, two years of drag makeup, and a final orbit rise to 700 km. The arcjet system was determined to halve the propulsion system wet mass required for that scenario as compared to hydrazine monopropellant thrusters.

Failure analysis of InGaN/GaN high power light-emitting diodes fabricated with ITO transparent p-type electrode during accelerated electro-thermal stress.

PubMed

Moon, Seong Min; Kim, Y D; Oh, S K; Park, M J; Kwak, Joon Seop

2012-05-01

We have investigated the high-temperature degradation of optical power as well as electrical properties of InGaN/GaN light-emitting diodes (LEDs) fabricated with ITO transparent p-electrode during accelerated electro-thermal stress. As the thermal stress increased from 150 degrees C to 250 degrees C at a electrical stress of 200 mA, the optical power of the LEDs was significantly reduced. Degradation of the optical power was thermally activated, with the activation of 0.9 eV. In addition, the activation energy of the degradation of optical power was fairly similar to that of the degradation of series resistance of the LEDs, 1.0 eV, which implies that the increase in the series resistance may result in the severe degradation of optical power. We also showed that the increase in the series resistance of the LEDs during the accelerated electro-thermal stress can be attributed to reduction of the active acceptor concentration in the p-type semiconductor layers and local joule heating due to the current crowding.

The Pharmacokinetics of Atomized Lidocaine Administered via the Trachea: A Randomized Trial.

PubMed

Takaenoki, Yumiko; Masui, Kenichi; Oda, Yutaka; Kazama, Tomiei

2016-07-01

Under emergent conditions, endotracheal drug administration may be an effective method of delivering emergency drugs. A common technique is to administer these drugs using a nonatomized spray. Atomized drug delivery may be an attractive alternative to nonatomized delivery because atomized particles are small, cover a large surface area, and may better adhere to endotracheal membrane resulting in more effective drug absorption. In this study, we compared the pharmacokinetic profile of lidocaine administered into the trachea using an atomized or a nonatomized technique. Twenty patients were anesthetized using propofol and remifentanil. Ten minutes after rocuronium was administered, patients received 4% lidocaine (2 mg/kg) intratracheally over 2 seconds before tracheal intubation. Ten patients received atomized lidocaine using a mucosal atomization device, and the other 10 patients received nonatomized lidocaine using a traditional spray tube. Arterial lidocaine plasma concentrations were measured before; at 1, 3, 5, 7, 10, 15, 20, 30, 45, and 60 minutes; and then every 60 minutes after the administration of lidocaine until the end of the operation. We developed a pharmacokinetic model to examine whether bioavailability or absorption rate was different between atomized versus nonatomized lidocaine administration. The total body clearance was fixed at a published value to determine the bioavailability. Peak plasma concentrations were larger using the mucosal atomization device (median [range]: 1.9 [1.4-3.2] μg/mL) than the spray tube (1.1 [0.6-2.0] μg/mL; P = 0.0021). Our pharmacokinetic model estimated a difference of bioavailability between the atomized and the nonatomized lidocaine (0.801 and 0.559 respectively, P = 0.0005), whereas our model estimated no difference in the absorption rate constant (0.00688/min). Our results suggest that when using atomized delivery of lidocaine, less drug is required to achieve a near equivalent plasma lidocaine concentration. Atomized drug administration may be a more efficient method for endotracheal drug administration.

[Measurement of atomic number of alkali vapor and pressure of buffer gas based on atomic absorption].

PubMed

Zheng, Hui-jie; Quan, Wei; Liu, Xiang; Chen, Yao; Lu, Ji-xi

2015-02-01

High sensitivitymagnetic measurementscanbe achieved by utilizing atomic spinmanipulation in the spin-exchange-relaxation-free (SERF) regime, which uses an alkali cell as a sensing element. The atomic number density of the alkali vapor and the pressure of the buffer gasare among the most important parameters of the cell andrequire accurate measurement. A method has been proposed and developedto measure the atomic number density and the pressure based on absorption spectroscopy, by sweeping the absorption line and fittingthe experiment data with a Lorentzian profile to obtainboth parameters. Due to Doppler broadening and pressure broadening, which is mainly dominated by the temperature of the cell and the pressure of buffer gas respectively, this work demonstrates a simulation of the errorbetween the peaks of the Lorentzian profile and the Voigt profile caused by bothfactors. The results indicates that the Doppler broadening contribution is insignificant with an error less than 0.015% at 313-513 K for a 4He density of 2 amg, and an error of 0.1% in the presence of 0.6-5 amg at 393 K. We conclude that the Doppler broadening could be ignored under above conditions, and that the Lorentzianprofile is suitably applied to fit the absorption spectrumobtainingboth parameters simultaneously. In addition we discuss the resolution and the instability due to thelight source, wavelength and the temperature of the cell. We find that the cell temperature, whose uncertainty is two orders of magnitude larger than the instability of the light source and the wavelength, is one of the main factors which contributes to the error.

Design strategies to minimize the radiative efficiency of global warming molecules

PubMed Central

Bera, Partha P.; Francisco, Joseph S.; Lee, Timothy J.

2010-01-01

A strategy is devised to screen molecules based on their radiative efficiency. The methodology should be useful as one additional constraint when determining the best molecule to use for an industrial application. The strategy is based on the results of a recent study where we examined molecular properties of global warming molecules using ab initio electronic structure methods to determine which fundamental molecular properties are important in assessing the radiative efficiency of a molecule. Six classes of perfluorinated compounds are investigated. For similar numbers of fluorine atoms, their absorption of radiation in the IR window decreases according to perfluoroethers > perfluorothioethers ≈ sulfur/carbon compounds > perfluorocarbons > perfluoroolefins > carbon/nitrogen compounds. Perfluoroethers and hydrofluorethers are shown to possess a large absorption in the IR window due to (i) the C─O bonds are very polar, (ii) the C-O stretches fall within the IR window and have large IR intensity due to their polarity, and (iii) the IR intensity for C-F stretches in which the fluorine atom is bonded to the carbon that is bonded to the oxygen atom is enhanced due to a larger C─F bond polarity. Lengthening the carbon chain leads to a larger overall absorption in the IR window, though the IR intensity per bond is smaller. Finally, for a class of partially fluorinated compounds with a set number of electronegative atoms, the overall absorption in the IR window can vary significantly, as much as a factor of 2, depending on how the fluorine atoms are distributed within the molecule. PMID:20439762

Near-edge X-ray absorption spectra for metallic Cu and Mn

NASA Astrophysics Data System (ADS)

Greaves, G. N.; Durham, P. J.; Diakun, G.; Quinn, P.

1981-11-01

The measurement of X-ray absorption fine structure of metals- both in the extended region (EXAFS) as well as in the near edge region (XANES)-has been widely discussed (see refs 1-6 for Cu and refs 7-9 for Mn). The recent availability of intense X-ray fluxes from storage rings has usually been exploited for EXAFS leaving the XANES often with poorer resolution than earlier work performed on conventional sources (for example, compare the near edge structure for copper in ref. 1 with refs 3 or 6). In addition, whilst the theory and analysis of EXAFS is relatively well-established2,10, a theory for the strong scattering regime near to the absorption edge has only recently been developed11. We report here the first high resolution XANES spectra for Cu and Mn which were performed at the SRS storage ring at Daresbury. Although both metals have close-packed structures consisting of atoms of similar size their local atomic structure is different in detail. Significant differences are found in their respective XANES reflecting the senstivity of this region of the X-ray absorption fine structure to the local atomic structure. Spectra for the two metals have been analysed using the new multiple scattering formalism. This is a real space calculation and unlike a conventional band structure approach it does not require structural periodicity but works from the local arrangement of atoms.

Wide-band 'black silicon' with atomic layer deposited NbN.

PubMed

Isakov, Kirill; Perros, Alexander Pyymaki; Shah, Ali; Lipsanen, Harri

2018-08-17

Antireflection surfaces are often utilized in optical components to reduce undesired reflection and increase absorption. We report on black silicon (b-Si) with dramatically enhanced absorption over a broad wavelength range (250-2500 nm) achieved by applying a 10-15 nm conformal coating of NbN with atomic layer deposition (ALD). The improvement is especially pronounced in the near infrared (NIR) range of 1100-2500 nm where absorption is increased by >90%. A significant increase of absorption is also observed over the ultraviolet range of 200-400 nm. Preceding NbN deposition with a nanostructured ALD Al 2 O 3 (n-Al 2 O 3 ) coating to enhance the NbN texture was also examined. Such texturing further improves absorption in the NIR, especially at longer wavelengths, strong absorption up to 4-5 μm wavelengths has been attested. For comparison, double side polished silicon and sapphire coated with 10 nm thick NbN exhibited absorption of only ∼55% in the NIR range of 1100-2500 nm. The results suggest a positive correlation between the surface area of NbN coating and optical absorption. Based on the wide-band absorption, the presented NbN-coated b-Si may be an attractive candidate for use in e.g. spectroscopic systems, infrared microbolometers.

High-stroke silicon-on-insulator MEMS nanopositioner: Control design for non-raster scan atomic force microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maroufi, Mohammad, E-mail: Mohammad.Maroufi@uon.edu.au; Fowler, Anthony G., E-mail: Anthony.Fowler@uon.edu.au; Bazaei, Ali, E-mail: Ali.Bazaei@newcastle.edu.au

A 2-degree of freedom microelectromechanical systems nanopositioner designed for on-chip atomic force microscopy (AFM) is presented. The device is fabricated using a silicon-on-insulator-based process and is designed as a parallel kinematic mechanism. It contains a central scan table and two sets of electrostatic comb actuators along each orthogonal axis, which provides displacement ranges greater than ±10 μm. The first in-plane resonance modes are located at 1274 Hz and 1286 Hz for the X and Y axes, respectively. To measure lateral displacements of the stage, electrothermal position sensors are incorporated in the design. To facilitate high-speed scans, the highly resonant dynamics ofmore » the system are controlled using damping loops in conjunction with internal model controllers that enable accurate tracking of fast sinusoidal set-points. To cancel the effect of sensor drift on controlled displacements, washout controllers are used in the damping loops. The feedback controlled nanopositioner is successfully used to perform several AFM scans in contact mode via a Lissajous scan method with a large scan area of 20 μm × 20 μm. The maximum scan rate demonstrated is 1 kHz.« less

The Covidien LigaSure Maryland Jaw Device.

PubMed

Zaidi, Nisar; Glover, Anthony R; Sidhu, Stanley B

2015-03-01

Since its invention nearly 20 years ago, the Covidien LigaSure device along with its ForceTriad generator has dominated the Electrothermal Bipolar Vessel Sealing market. The LigaSure was used for surgical procedures, both open and laparoscopic. The purpose of this review is to provide evidence of the safety and utility of the LigaSure device compared to more traditional means of hemostasis and its ultrasonic competitor, particularly in laparoscopic applications. We will provide evidence related to electrothermal bipolar vessel sealing in general and look specifically at Covidien's newest product, the LigaSure Maryland Jaw Device.

Gas dynamic model of electrothermal thrusters of small spacecraft and possibility of applying microwave heating of a working

NASA Astrophysics Data System (ADS)

Blinov, V. N.; Shalay, V. V.; Vavilov, I. S.; Kositsin, V. V.; Ruban, V. I.; Lykyanchik, A. I.; Yachmenev, P. S.; Vlasov, A. S.

2017-06-01

This paper is devoted to development and approbation of the gas dynamic model of ammonia thruster with low power consumption and ultra small thrust for picosatellite weighing up to 5 kg and possibility of applying microwave heating of a working fluid. It is shown, that simplest electrothermal thruster consisting of propellant tank, solenoid valve, expension cavity and heating chamber can provide ultra small trust due to gas dynamic processes and small heat supply. The results of the study set tasks for further design of small spacecrafts microwave generators.

Absorption spectroscopy of heavy alkaline earth metals Ba and Sr in rare gas matrices—CCSD(T) calculations and atomic site occupancies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, Barry M.; McCaffrey, John G., E-mail: john.mccaffrey@nuim.ie

2016-01-28

Isolation of the heavier alkaline earth metals Ba and Sr in the solid rare gases (RGs) Ar, Kr, and Xe is analysed with absorption spectroscopy and interpreted partly with the assistance of ab initio calculations of the diatomic M ⋅ RG ground state interaction potentials. The y{sup 1}P←a{sup 1}S resonance transitions in the visible spectral region are used to compare the isolation conditions of these two metal atom systems and calcium. Complex absorption bands were recorded in all three metal atom systems even after extensive sample annealing. Coupled cluster calculations conducted on the ground states of the nine M ⋅more » RG diatomics (M = Ca, Sr, and Ba; RG = Ar, Kr, and Xe) at the coupled cluster single, double, and non-iterative triple level of theory revealed long bond lengths (>5 Å) and shallow bound regions (<130 cm{sup −1}). All of the M ⋅ RG diatomics have bond lengths considerably longer than those of the rare gas dimers, with the consequence that isolation of these metal atoms in a single substitutional site of the solid rare gas is unlikely, with the possible exception of Ca/Xe. The luminescence of metal dimer bands has been recorded for Ba and Sr revealing very different behaviours. Resonance fluorescence with a lifetime of 15 ns is observed for the lowest energy transition of Sr{sub 2} while this transition is quenched in Ba{sub 2}. This behaviour is consistent with the absence of vibrational structure on the dimer absorption band in Ba{sub 2} indicating lifetime broadening arising from efficient relaxation to low-lying molecular states. More extensive 2D excitation-emission data recorded for the complex site structures present on the absorption bands of the atomic Ba and Sr systems will be presented in future publications.« less

ADVANCED APPROACHES TO ARSINE ATOMIZATION FOR AS SPECIATION BY CRYOFOCUSING WITH ATOMIC ABSORPTION AND ATOMIC FLUORESCENCE DETECTORS

EPA Science Inventory

Human metabolism of inorganic arsenic (iAs) yields methylated arsenicals that contain arsenic in +3 or +5 oxidation state. Trivalent methylated arsenicals are significantly more toxic than their pentavalent counterparts. Therefore, determination of tri- and pentavalent forms of m...

Quantum state-resolved probing of strong-field-ionized xenon atoms using femtosecond high-order harmonic transient absorption spectroscopy.

PubMed

Loh, Zhi-Heng; Khalil, Munira; Correa, Raoul E; Santra, Robin; Buth, Christian; Leone, Stephen R

2007-04-06

Femtosecond high-order harmonic transient absorption spectroscopy is used to resolve the complete |j,m quantum state distribution of Xe+ produced by optical strong-field ionization of Xe atoms at 800 nm. Probing at the Xe N4/5 edge yields a population distribution rhoj,|m| of rho3/2,1/2ratiorho1/2,1/2ratiorho3/2,3/2=75+/-6 :12+/-3 :13+/-6%. The result is compared to a tunnel ionization calculation with the inclusion of spin-orbit coupling, revealing nonadiabatic ionization behavior. The sub-50-fs time resolution paves the way for tabletop extreme ultraviolet absorption probing of ultrafast dynamics.

Atomic-scale distortion of optically activated Sm dopants identified with site-selective X-ray absorption spectroscopy

NASA Astrophysics Data System (ADS)

Ishii, Masashi; Crowe, Iain F.; Halsall, Matthew P.; Hamilton, Bruce; Hu, Yongfeng; Sham, Tsun-Kong; Harako, Susumu; Zhao, Xin-Wei; Komuro, Shuji

2013-10-01

The local structure of luminescent Sm dopants was investigated using an X-ray absorption fine-structure technique with X-ray-excited optical luminescence. Because this technique evaluates X-ray absorption from luminescence, only optically active sites are analyzed. The Sm L3 near-edge spectrum contains split 5d states and a shake-up transition that are specific to luminescent Sm. Theoretical calculations using cluster models identified an atomic-scale distortion that can reproduce the split 5d states. The model with C4v local symmetry and compressive bond length of Sm-O of a six-fold oxygen (SmO6) cluster is most consistent with the experimental results.

Oxygen vacancy mediated enhanced photo-absorption from ZnO(0001) nanostructures fabricated by atom beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Solanki, Vanaraj; Joshi, Shalik R.; Mishra, Indrani

2016-08-07

The nanoscale patterns created on the ZnO(0001) surfaces during atom beam irradiation have been investigated here for their photo absorption response. Preferential sputtering, during irradiation, promotes Zn-rich zones that serve as the nucleation centers for the spontaneous creation of nanostructures. Nanostructured surfaces with bigger (78 nm) nanodots, displaying hexagonal ordering and long ranged periodic behavior, show higher photo absorption and a ∼0.09 eV reduced bandgap. These nanostructures also demonstrate higher concentration of oxygen vacancies which are crucial for these results. The enhanced photo-response, as observed here, has been achieved in the absence of any dopant elements.

Approaching perfect absorption of monolayer molybdenum disulfide at visible wavelengths using critical coupling.

PubMed

Jiang, Xiaoyun; Wang, Tao; Xiao, Shuyuan; Yan, Xicheng; Cheng, Le; Zhong, Qingfang

2018-08-17

A simple perfect absorption structure is proposed to achieve the high efficiency light absorption of monolayer molybdenum disulfide (MoS 2 ) by the critical coupling mechanism of guided resonances. The results of numerical simulation and theoretical analysis show that the light absorption in this atomically thin layer can be as high as 98.3% at the visible wavelengths, which is over 12 times more than that of a bare monolayer MoS 2 . In addition, the operating wavelength can be tuned flexibly by adjusting the radius of the air hole and the thickness of the dielectric layers, which is of great practical significance to improve the efficiency and selectivity of the absorption in monolayer MoS 2 . The novel idea of using critical coupling to enhance the light-MoS 2 interaction can be also adopted in other atomically thin materials. The meaningful improvement and tunability of the absorption in monolayer MoS 2 provides a good prospect for the realization of high-performance MoS 2 -based optoelectronic applications, such as photodetection and photoluminescence.

Specification of Butyltins and Methyltins in Seawater and Marine Sediments by Hydride Derivatization and Atomic Absorption Detection.

DTIC Science & Technology

1985-07-01

Corporation . - P.F. Seligman . . Naval Ocean Systems Center fTW G. Vafa University of Hawaii Research Corporation P.M. Stang DEC 0 4 198 1: San Diego State...NAVFAC 032) under the Marine Environmental Quality Assessment Program. Released by Under authority of P. F. Seligman , Head S. Yamamoto, Head Marine...SEDIMENTS BY HYDRIDE DERIVATIZATION AND ATOMIC ABSORPTION DETECTION 12 PERSONAL AUJTHORWS) A. 0. Valkirs, P. F. Seligman , G. Vafa, P. M. Stang, V. Homner

Major and trace element concentrations in samples from 72275 and 72255. [chemical composition of lunar rocks

NASA Technical Reports Server (NTRS)

Haskin, L. A.; Blanchard, D. P.; Korotev, R.; Jacobs, J. W.; Brannon, J. A.; Herrmann, A. G.

1974-01-01

Analytical data have been obtained for Co, Sc, Hf, Zn, Cr, Ga, Rb, Cs, Ni, major elements, and rare earth elements in eight samples from boulder 1. The data for trace elements were obtained by radiochemical neutron activation analysis. Major elements, except Na and Mn, were obtained by atomic absorption spectral photometry. Values for Na and Mn were obtained by neutron activation analysis of the same powder that was later dissolved to provide the atomic absorption analyses.

Determination of traces of silicone defoamer in fruit juices by solvent extraction/atomic absorption spectroscopy.

PubMed

Gooch, E G

1993-01-01

Silicone defoamers are used to control foam during the processing of fruit juices. Residual silicones in fruit juices can be separated from the naturally occurring siliceous materials in fruit products and selectively recovered by solvent extraction, after suitable pretreatment. The recovered silicone is measured by atomic absorption spectroscopy. Silicone concentrations as low as about 1 ppm can be measured. The juices are accurately spiked for recovery studies by the addition of silicone dispersed in D-sorbitol.

[Determination of mercury in Boletus impolitus by flow injection-atomic absorption spectrometry].

PubMed

Li, Tao; Wang, Yuan-Zhong

2008-04-01

Various test conditions and effect factors for the determination of mercury by flow injection-atomic absorption spectrometry were discussed, and a method for the determination of mercury in Boletus impolitus has been developed. The linear range for mercury is 0-60 microg x L(-1). The relative standard deviation is less than 3.0%, and the recovery is 96%-107%. This method is simple, rapid and has been applied to the determination of mercury in Boletus impolitus samples with satisfactory results.

Determination of silver in irons and steels by atomic-absorption spectrometry with an induction furnace: Direct analysis of solid samples.

PubMed

Aziz-Alrahman, A M; Headridge, J B

1978-07-01

The silver contents of 17 irons and steels have been determined by dropping 0.5-20mg of millings or turnings of the metals into an induction furnace situated within an atomic-absorption spectrophotometer. The limit of detection was 0.005 mug/g and the relative standard deviations were 12% or better for silver contents of not less than 0.05 mug/g. Samples are added to the furnace at 4-5 min intervals.

Investigation of an alternating current plasma as an element selective atomic emission detector for high-resolution capillary gas chromatography and as a source for atomic absorption and atomic emission spectrometry

NASA Astrophysics Data System (ADS)

Ombaba, Jackson M.

This thesis deals with the construction and evaluation of an alternating current plasma (ACP) as an element-selective detector for high resolution capillary gas chromatography (GC) and as an excitation source for atomic absorption spectrometry (AAS) and atomic emission spectrometry (AES). The plasma, constrained in a quartz discharge tube at atmospheric pressure, is generated between two copper electrodes and utilizes helium as the plasma supporting gas. The alternating current plasma power source consists of a step-up transformer with a secondary output voltage of 14,000 V at a current of 23 mA. The device exhibits a stable signal because the plasma is self-seeding and reignites itself every half cycle. A tesla coil is not required to commence generation of the plasma if the ac voltage applied is greater than the breakdown voltage of the plasma-supporting gas. The chromatographic applications studied included the following: (1) the separation and selective detection of the organotin species, tributyltin chloride (TBT) and tetrabutyltin (TEBT), in environmental matrices including mussels (Mvutilus edullus) and sediment from Boston Harbor, industrial waste water and industrial sludge, and (2) the detection of methylcyclopentadienyl manganesetricarbonyl (MMT) and similar compounds used as gasoline additives. An ultrasonic nebulizer (common room humidifier) was utilized as a sample introduction device for aqueous solutions when the ACP was employed as an atomization source for atomic absorption spectrometry and as an excitation source for atomic emission spectrometry. Plasma diagnostic parameters studied include spatial electron number density across the discharge tube, electronic, excitation and ionization temperatures. Interference studies both in absorption and emission modes were also considered. Figures of merits of selected elements both in absorption and emission modes are reported. The evaluation of a computer-aided optimization program, Drylab GC, using spearmint oil and Environmental Protection Agency (EPA) standard mixture as probes is also discussed. The program supplied by LC Resources (Lafayette, CA) is used for separation optimization and prediction of gas chromatographic parameters. Column dead-time and average plate number were used as input data in conjunction with the retention times and peak areas of solutes at two different temperature programming rates. Once input data are entered into an IBM or IBM compatible personal computer, the program produces a 'relative resolution map' (RRM) which guides the analyst in selecting the most favorable temperature programming rate for the separation.

Simultaneous multielement atomic absorption spectrometry with graphite furnace atomization

NASA Astrophysics Data System (ADS)

Harnly, James M.; Miller-Ihli, Nancy J.; O'Haver, Thomas C.

The extended analytical range capability of a simultaneous multielement atomic absorption continuum source spectrometer (SIMAAC) was tested for furnace atomization with respect to the signal measurement mode (peak height and area), the atomization mode (from the wall or from a platform), and the temperature program mode (stepped or ramped atomization). These parameters were evaluated with respect to the shapes of the analytical curves, the detection limits, carry-over contamination and accuracy. Peak area measurements gave more linear calibration curves. Methods for slowing the atomization step heating rate, the use of a ramped temperature program or a platform, produced similar calibration curves and longer linear ranges than atomization with a stepped temperature program. Peak height detection limits were best using stepped atomization from the wall. Peak area detection limits for all atomization modes were similar. Carry-over contamination was worse for peak area than peak height, worse for ramped atomization than stepped atomization, and worse for atomization from a platform than from the wall. Accurate determinations (100 ± 12% for Ca, Cu, Fe, Mn, and Zn in National Bureau of Standards' Standard Reference Materials Bovine Liver 1577 and Rice Flour 1568 were obtained using peak area measurements with ramped atomization from the wall and stepped atomization from a platform. Only stepped atomization from a platform gave accurate recoveries for K. Accurate recoveries, 100 ± 10%, with precisions ranging from 1 to 36 % (standard deviation), were obtained for the determination of Al, Co, Cr, Fe, Mn, Mo, Ni. Pb, V and Zn in Acidified Waters (NBS SRM 1643 and 1643a) using stepped atomization from a platform.

Identification of F impurities in F-doped ZnO by synchrotron X-ray absorption near edge structures

NASA Astrophysics Data System (ADS)

Na-Phattalung, Sutassana; Limpijumnong, Sukit; Min, Chul-Hee; Cho, Deok-Yong; Lee, Seung-Ran; Char, Kookrin; Yu, Jaejun

2018-04-01

Synchrotron X-ray absorption near edge structure (XANES) measurements of F K-edge in conjunction with first-principles calculations are used to identify the local structure of the fluorine (F) atom in F-doped ZnO. The ZnO film was grown by pulsed laser deposition with an Nd:YAG laser, and an oxyfluoridation method was used to introduce F ions into the ZnO films. The measured XANES spectrum of the sample was compared against the first-principles XANES calculations based on various models for local atomic structures surrounding F atoms. The observed spectral features are attributed to ZnF2 and FO defects in wurtzite bulk ZnO.

Measurements of sulfur compounds in CO 2 by diode laser atomic absorption spectrometry

NASA Astrophysics Data System (ADS)

Franzke, J.; Stancu, D. G.; Niemax, K.

2003-07-01

Two simple methods for the analysis of the total concentration of sulfur in CO 2 by diode laser atomic absorption spectrometry of excited, metastable sulfur atoms in a direct current discharge are presented. In the first method, the CO 2 sample gas is mixed with the plasma gas (Ar or He) while the second is based on reproducible measurements of the sulfur released from the walls in a helium discharge after being deposited as a result of operating the discharge in pure CO 2 sample gas. The detection limits obtained satisfy the requirements for the control of sulfur compounds in CO 2 used in the food and beverage industry.

Statistical evaluation of an inductively coupled plasma atomic emission spectrometric method for routine water quality testing

USGS Publications Warehouse

Garbarino, J.R.; Jones, B.E.; Stein, G.P.

1985-01-01

In an interlaboratory test, inductively coupled plasma atomic emission spectrometry (ICP-AES) was compared with flame atomic absorption spectrometry and molecular absorption spectrophotometry for the determination of 17 major and trace elements in 100 filtered natural water samples. No unacceptable biases were detected. The analysis precision of ICP-AES was found to be equal to or better than alternative methods. Known-addition recovery experiments demonstrated that the ICP-AES determinations are accurate to between plus or minus 2 and plus or minus 10 percent; four-fifths of the tests yielded average recoveries of 95-105 percent, with an average relative standard deviation of about 5 percent.

Electromagnetically induced absorption and transparency in degenerate two level systems of metastable Kr atoms and measurement of Landé g-factor

NASA Astrophysics Data System (ADS)

Kale, Y. B.; Tiwari, V. B.; Mishra, S. R.; Singh, S.; Rawat, H. S.

2016-12-01

We report electromagnetically induced absorption (EIA) and transparency (EIT) resonances of sub-natural linewidth in degenerate two level systems (DTLSs) of metastable 84Kr (84Kr*) and 83Kr (83Kr*) atoms. Using the spectrally narrow EIA signals obtained corresponding to the closed hyperfine transition 4p55s[3/2]2(F=13/2) to 4p55p[5/2]3(F‧ = 15 / 2) in 83Kr* atom, we have measured the Landé g-factor (gF) for the lower hyperfine level involved in this transition by application of small values of magnetic field of few Gauss.

Exploration geochemical technique for the determination of preconcentrated organometallic halides by ICP-AES

USGS Publications Warehouse

Motooka, J.M.

1988-01-01

An atomic absorption extraction technique which is widely used in geochemical exploration for the determination of Ag, As, Au, Bi, Cd, Cu, Mo, Pb, Sb, and Zn has been modified and adapted to a simultaneous inductively coupled plasma-atomic emission instrument. the experimental and operating parameters are described for the preconcentration of the metals into their organometallic halides and for the determination of the metals. Lower limits of determination are equal to or improved over those for flame atomic absorption (except Au) and ICP results are very similar to the accepted AA values, with precision for the ICP data in excess of that necessary for exploration purposes.

Local atomic and electronic structures of epitaxial strained LaCoO3 thin films

NASA Astrophysics Data System (ADS)

Sterbinsky, G. E.; Ryan, P. J.; Kim, J.-W.; Karapetrova, E.; Ma, J. X.; Shi, J.; Woicik, J. C.

2012-01-01

We have examined the atomic and electronic structures of perovskite lanthanum cobaltite (LaCoO3) thin films using Co K-edge x-ray absorption fine structure (XAFS) spectroscopy. Extended XAFS (EXAFS) demonstrates that a large difference between in-plane and out-of-plane Co-O bond lengths results from tetragonal distortion in highly strained films. The structural distortions are strongly coupled to the hybridization between atomic orbitals of the Co and O atoms, as shown by x-ray absorption near edge spectroscopy (XANES). Our results indicate that increased hybridization is not the cause of ferromagnetism in strained LaCoO3 films. Instead, we suggest that the strain-induced distortions of the oxygen octahedra increase the population of eg electrons and concurrently depopulate t2g electrons beyond a stabilization threshold for ferromagnetic order.

The Electronic Structure and Optical Properties of Anatase TiO₂ with Rare Earth Metal Dopants from First-Principles Calculations.

PubMed

Xie, Kefeng; Jia, Qiangqiang; Wang, Yizhe; Zhang, Wenxue; Xu, Jingcheng

2018-01-24

The electronic and optical properties of the rare earth metal atom-doped anatase TiO₂ have been investigated systematically via density functional theory calculations. The results show that TiO₂ doped by Ce or Pr is the optimal choice because of its small band gap and strong optical absorption. Rare earth metal atom doping induces several impurity states that tune the location of valence and conduction bands and an obvious lattice distortion that should reduce the probability of electron-hole recombination. This effect of band change originates from the 4 f electrons of the rare earth metal atoms, which leads to an improved visible light absorption. This finding indicates that the electronic structure of anatase TiO₂ is tuned by the introduction of impurity atoms.

The Electronic Structure and Optical Properties of Anatase TiO2 with Rare Earth Metal Dopants from First-Principles Calculations

PubMed Central

Xie, Kefeng; Jia, Qiangqiang; Wang, Yizhe; Zhang, Wenxue; Xu, Jingcheng

2018-01-01

The electronic and optical properties of the rare earth metal atom-doped anatase TiO2 have been investigated systematically via density functional theory calculations. The results show that TiO2 doped by Ce or Pr is the optimal choice because of its small band gap and strong optical absorption. Rare earth metal atom doping induces several impurity states that tune the location of valence and conduction bands and an obvious lattice distortion that should reduce the probability of electron–hole recombination. This effect of band change originates from the 4f electrons of the rare earth metal atoms, which leads to an improved visible light absorption. This finding indicates that the electronic structure of anatase TiO2 is tuned by the introduction of impurity atoms. PMID:29364161

Flow injection analysis-flame atomic absorption spectrometry system for indirect determination of sulfite after on-line reduction of solid-phase manganese (IV) dioxide reactor.

PubMed

Zare-Dorabei, Rouholah; Boroun, Shokoufeh; Noroozifar, Meissam

2018-02-01

A new and simple flow injection method followed by atomic absorption spectrometry was developed for indirect determination of sulfite. The proposed method is based on the oxidation of sulfite to sulphate ion using solid-phase manganese dioxide (30% W/W suspended on silica gel beads) reactor. MnO 2 will be reduced to Mn(II) by sample injection in to the column under acidic carrier stream of HNO 3 (pH 2) with flow rate of 3.5mLmin -1 at room temperature. Absorption measurement of Mn(II) which is proportional to the concentration of sulfite in the sample was carried out by atomic absorption spectrometry. The calibration curve was linear up to 25mgL -1 with a detection limit (DL) of 0.08mgL -1 for 400µL injection sample volume. The presented method is efficient toward sulfite determination in sugar and water samples with a relative standard deviation (RSD) less than 1.2% and a sampling rate of about 60h -1 . Copyright © 2017 Elsevier B.V. All rights reserved.

A novel multi-actuation CMOS RF MEMS switch

NASA Astrophysics Data System (ADS)

Lee, Chiung-I.; Ko, Chih-Hsiang; Huang, Tsun-Che

2008-12-01

This paper demonstrates a capacitive shunt type RF MEMS switch, which is actuated by electro-thermal actuator and electrostatic actuator at the same time, and than latching the switching status by electrostatic force only. Since thermal actuators need relative low voltage compare to electrostatic actuators, and electrostatic force needs almost no power to maintain the switching status, the benefits of the mechanism are very low actuation voltage and low power consumption. Moreover, the RF MEMS switch has considered issues for integrated circuit compatible in design phase. So the switch is fabricated by a standard 0.35um 2P4M CMOS process and uses wet etching and dry etching technologies for postprocess. This compatible ability is important because the RF characteristics are not only related to the device itself. If a packaged RF switch and a packaged IC wired together, the parasitic capacitance will cause the problem for optimization. The structure of the switch consists of a set of CPW transmission lines and a suspended membrane. The CPW lines and the membrane are in metal layers of CMOS process. Besides, the electro-thermal actuators are designed by polysilicon layer of the CMOS process. So the RF switch is only CMOS process layers needed for both electro-thermal and electrostatic actuations in switch. The thermal actuator is composed of a three-dimensional membrane and two heaters. The membrane is a stacked step structure including two metal layers in CMOS process, and heat is generated by poly silicon resistors near the anchors of membrane. Measured results show that the actuation voltage of the switch is under 7V for electro-thermal added electrostatic actuation.

Electrothermal flow effects in insulating (electrodeless) dielectrophoresis systems.

PubMed

Hawkins, Benjamin G; Kirby, Brian J

2010-11-01

We simulate electrothermally induced flow in polymeric, insulator-based dielectrophoresis (iDEP) systems with DC-offset, AC electric fields at finite thermal Péclet number, and we identify key regimes where electrothermal (ET) effects enhance particle deflection and trapping. We study a single, two-dimensional constriction in channel depth with parametric variations in electric field, channel geometry, fluid conductivity, particle electrophoretic (EP) mobility, and channel electroosmotic (EO) mobility. We report the effects of increasing particle EP mobility, channel EO mobility, and AC and DC field magnitudes on the mean constriction temperature and particle behavior. Specifically, we quantify particle deflection and trapping, referring to the deviation of particles from their pathlines due to dielectrophoresis as they pass a constriction and the stagnation of particles due to negative dielectrophoresis near a constriction, respectively. This work includes the coupling between fluid, heat, and electromagnetic phenomena via temperature-dependent physical parameters. Results indicate that the temperature distribution depends strongly on the fluid conductivity and electric field magnitude, and particle deflection and trapping depend strongly on the channel geometry. Electrothermal (ET) effects perturb the EO flow field, creating vorticity near the channel constriction and enhancing the deflection and trapping effects. ET effects alter particle deflection and trapping responses in insulator-based dielectrophoresis devices, especially at intermediate device aspect ratios (2 ≤ r ≤ 7) in solutions of higher conductivity (σ m ≥ 1 × 10(-3)S/m). The impact of ET effects on particle deflection and trapping are diminished when particle EP mobility or channel EO mobility is high. In almost all cases, ET effects enhance negative dielectrophoretic particle deflection and trapping phenomena. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of Nitrates, Thiocyanates and Selenium on the Iron and Iodine Status of Postpartum Women.

PubMed

Bivolarska, Anelia V; Maneva, Ana I; Gatseva, Penka D; Katsarova, Mariana N

2016-09-01

To find correlations between high thiocyanate and nitrate levels and low selenium levels and the indicators of the iodine and iron status of postpartum women. The study included 41 mothers aged 26.4±5.9 yrs from Asenovgrad and nearby villages. Urinary iodine was determined by the Sandell-Kolthoff reaction and thiocyanate - by the interaction of these ions with acidic solution of KMnO4; for serum nitrates we used the colorimetric method; serum selenium was assessed by electro-thermal atomic-absorption spectrophotometry; thyroxin (FT4), the thyroid stimulating hormone (TSH), serum ferritin (SF), and serum transferrin receptor (sTfR) were determined using ELISA; Hb levels were determined by hematology analyzer. Assessing the iodine status, we found a negative correlation between the levels of iodine and thiocyanates in urine (R=-0.717, р<0.0001), a positive correlation between nitrates and TSH (R=0.487, р=0.003) and a negative correlation between nitrates and FT4 (R=-0.312, р=0.06). For the iron status, we found a negative correlation between nitrates and SF (R=-0.429, р=0.009) and between nitrates and Hb (R=-0.383, р=0.021). The Mann-Whitney U-test showed that in women with nitrate levels higher than the mean value there was low FT4 level (р=0.06), high TSH level (р=0.013), low Hb concentration (р=0.061) and low SF concentration (р=0.005). The combined effects of environmental factors (elevated nitrate levels and low selenium level) on the iodine and iron status are manifested by low concentrations of FT4 (р=0.033), Hb (р=0.06) and SF (р=0.05) and high level of TSH (р=0.05). In conclusion, we found that environmental factors, especially when combined, have a negative impact on the iron and iodine status of females.

Correlation of cadmium and aluminum in blood samples of kidney disorder patients with drinking water and tobacco smoking: related health risk.

PubMed

Panhwar, Abdul Haleem; Kazi, Tasneem Gul; Afridi, Hassan Imran; Arain, Salma Aslam; Arain, Mariam Shahzadi; Brahaman, Kapil Dev; Naeemullah; Arain, Sadaf Sadia

2016-02-01

The combined exposure to aluminum (Al) and cadmium (Cd) causes more pronounced adverse health effects on humans. The kidneys are the main organs affected by internal exposure to Cd and Al via food and non-food items. The objective of present study was to measure the Al and Cd concentrations in cigarettes tobacco (branded and non-branded) and drinking water (domestic treated, ground and lake water) samples in southern part of Pakistan, to assess the risk due to ingestion of water and inhalation of cigarettes smoke containing high concentrations of both elements. The study population (kidney disorder and healthy) divided into two group based on consuming lake and ground water, while smoking non-branded cigarette as exposed, while drinking domestic treated water and smoking branded cigarette as non-exposed. Electrothermal atomic absorption spectrometry was used to determined Cd and Al concentrations in tobacco, drinking water and blood samples. The resulted data indicated that the levels of Al and Cd in lake and underground water were higher than the permissible limit in drinking water recommended by the World Health Organization. The biochemical parameters of exposed and referent patients, especially urinary N-acetyl-h-glucosaminidase, were used as a biomarkers of kidney disorder. Exposed kidney disorder patients have higher levels of Cd and Al than the exposed referents subjects, while difference was significant when compared to resulted data of non-exposed patients and referents (p = 0.01-0.001). The pearson correlation showed positive correlation between both toxic element concentrations in water, cigarettes versus blood samples of exposed subjects (r = 0.20-0.67 and 0.71-0.82), while lower values were observed for non-exposed subjects (r = 0.123-0.423 and 0.331-0.425), respectively.

Particulate matter and heavy metal deposition on the leaves of Euonymus japonicus during the East Asian monsoon in Beijing, China

PubMed Central

Hong, Xiuling; Sun, Liwei

2017-01-01

Plants can be effectively used as bio-monitors of environmental pollution. However, how the particulate matter (PM) and heavy metal retention ability of plants changes in different areas with human disturbance along with monsoon has not yet been investigated in urban ecosystems. In this study, we measured the amount of PM and heavy metals such as Ni, Cr, Cu, Pb, and Zn accumulated by the leaves of Euonymus japonicus during the East Asian monsoon from different functional units in Beijing, China. A rinse-and-weigh method developed in our laboratory was used to determine the mass of the PM, and electro-thermal atomic absorption spectrometry was used for heavy metal analysis. We found that the types of functional units had little influence, whereas the monsoon had a significant effect on the deposition of PM: northwest areas during the monsoon had the lowest effect (with 0.005, 0.453, 0.643, and 1.569 g/m2 fine, coarse, large, and total PM, respectively), and the southeast areas during the monsoon had the highest effect (0.015, 2.687, 1.941, and 4.228 g/m2 for fine, coarse, large, and total PM, respectively). Notable, we found considerable variations in heavy metal accumulation across the functional units analyzed, that is, the accumulation level was higher in communities than in parks (P < 0.0001 for all heavy metals). Moreover, a positive relationship was found between PM retention and heavy metal accumulation by the leaves of E. japonicus. Taken together, our results suggested that the PM and heavy metal retention ability of E. japonicus was sensitive to human disturbance and monsoon in Beijing. Since E. japonicus is a widely distributed tree and has the ability of to purify the atmosphere, it is an ideal plant for mitigating urban environmental pollution. PMID:28662081

Evaluation of Low-Earth-Orbit Environmental Effects on International Space Station Thermal Control Materials

NASA Technical Reports Server (NTRS)

Dever, Joyce A.

1998-01-01

Many spacecraft thermal control coatings in low Earth orbit (LEO) can be affected by solar ultraviolet radiation and atomic oxygen. Ultraviolet radiation can darken some polymers and oxides commonly used in thermal control materials. Atomic oxygen can erode polymer materials, but it may reverse the ultraviolet-darkening effect on oxides. Maintaining the desired solar absorptance for thermal control coatings is important to assure the proper operating temperature of the spacecraft. Thermal control coatings to be used on the International Space Station (ISS) were evaluated for their performance after exposure in the NASA Lewis Research Center's Atomic Oxygen-Vacuum Ultraviolet Exposure (AO-VUV) facility. This facility simulated the LEO environments of solar vacuum ultraviolet (VUV) radiation (wavelength range, 115 to 200 nanometers (nm)) and VUV combined with atomic oxygen. Solar absorptance was measured in vacuo to eliminate the "bleaching" effects of ambient oxygen on VUV-induced degradation. The objective of these experiments was to determine solar absorptance increases of various thermal control materials due to exposure to simulated LEO conditions similar to those expected for ISS. Work was done in support of ISS efforts at the requests of Boeing Space and Defense Systems and Lockheed Martin Vought Systems.

Development and Validation of a Sensitive Method for Trace Nickel Determination by Slotted Quartz Tube Flame Atomic Absorption Spectrometry After Dispersive Liquid-Liquid Microextraction.

PubMed

Yolcu, Şükran Melda; Fırat, Merve; Chormey, Dotse Selali; Büyükpınar, Çağdaş; Turak, Fatma; Bakırdere, Sezgin

2018-05-01

In this study, dispersive liquid-liquid microextraction was systematically optimized for the preconcentration of nickel after forming a complex with diphenylcarbazone. The measurement output of the flame atomic absorption spectrometer was further enhanced by fitting a custom-cut slotted quartz tube to the flame burner head. The extraction method increased the amount of nickel reaching the flame and the slotted quartz tube increased the residence time of nickel atoms in the flame to record higher absorbance. Two methods combined to give about 90 fold enhancement in sensitivity over the conventional flame atomic absorption spectrometry. The optimized method was applicable over a wide linear concentration range, and it gave a detection limit of 2.1 µg L -1 . Low relative standard deviations at the lowest concentration in the linear calibration plot indicated high precision for both extraction process and instrumental measurements. A coal fly ash standard reference material (SRM 1633c) was used to determine the accuracy of the method, and experimented results were compatible with the certified value. Spiked recovery tests were also used to validate the applicability of the method.

Self-assembly based plasmonic arrays tuned by atomic layer deposition for extreme visible light absorption.

PubMed

Hägglund, Carl; Zeltzer, Gabriel; Ruiz, Ricardo; Thomann, Isabell; Lee, Han-Bo-Ram; Brongersma, Mark L; Bent, Stacey F

2013-07-10

Achieving complete absorption of visible light with a minimal amount of material is highly desirable for many applications, including solar energy conversion to fuel and electricity, where benefits in conversion efficiency and economy can be obtained. On a fundamental level, it is of great interest to explore whether the ultimate limits in light absorption per unit volume can be achieved by capitalizing on the advances in metamaterial science and nanosynthesis. Here, we combine block copolymer lithography and atomic layer deposition to tune the effective optical properties of a plasmonic array at the atomic scale. Critical coupling to the resulting nanocomposite layer is accomplished through guidance by a simple analytical model and measurements by spectroscopic ellipsometry. Thereby, a maximized absorption of light exceeding 99% is accomplished, of which up to about 93% occurs in a volume-equivalent thickness of gold of only 1.6 nm. This corresponds to a record effective absorption coefficient of 1.7 × 10(7) cm(-1) in the visible region, far exceeding those of solid metals, graphene, dye monolayers, and thin film solar cell materials. It is more than a factor of 2 higher than that previously obtained using a critically coupled dye J-aggregate, with a peak width exceeding the latter by 1 order of magnitude. These results thereby substantially push the limits for light harvesting in ultrathin, nanoengineered systems.

Alternating absorption features during attosecond-pulse propagation in a laser-controlled gaseous medium

NASA Astrophysics Data System (ADS)

Pfeiffer, Adrian N.; Bell, M. Justine; Beck, Annelise R.; Mashiko, Hiroki; Neumark, Daniel M.; Leone, Stephen R.

2013-11-01

Recording the transmitted spectrum of a weak attosecond pulse through a medium, while a strong femtosecond pulse copropagates at variable delay, probes the strong-field dynamics of atoms, molecules, and solids. Usually, the interpretation of these measurements is based on the assumption of a thin medium. Here, the propagation through a macroscopic medium of helium atoms in the region of fully allowed resonances is investigated both theoretically and experimentally. The propagation has dramatic effects on the transient spectrum even at relatively low pressures (50 mbar) and short propagation lengths (1 mm). The absorption does not evolve monotonically with the product of propagation distance and pressure, but regions with characteristics of Lorentz line shapes and characteristics of Fano line shapes alternate. Criteria are deduced to estimate whether macroscopic effects can be neglected or not in a transient absorption experiment. Furthermore, the theory in the limit of single-atom response yields a general equation for Lorentz- and Fano-type line shapes at variable pulse delay.

Carbon X-ray absorption in the local ISM: fingerprints in X-ray Novae spectra

NASA Astrophysics Data System (ADS)

Gatuzz, Efraín; Ness, J.-U.; Gorczyca, T. W.; Hasoglu, M. F.; Kallman, Timothy R.; García, Javier A.

2018-06-01

We present a study of the C K-edge using high-resolution LETGS Chandra spectra of four novae during their super-soft-source (SSS) phase. We identified absorption lines due to C II Kα, C III Kα and C III Kβ resonances. We used these astronomical observations to perform a benchmarking of the atomic data, which involves wavelength shifts of the resonances and photoionization cross-sections. We used improved atomic data to estimate the C II and C III column densities. The absence of physical shifts for the absorption lines, the consistence of the column densities between multiple observations and the high temperature required for the SSS nova atmosphere modeling support our conclusion about an ISM origin of the respective absorption lines. Assuming a collisional ionization equilibrium plasma the maximum temperature derived from the ratio of C II/C III column densities of the absorbers correspond to Tmax < 3.05 × 104 K.

Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

NASA Astrophysics Data System (ADS)

Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; Ozkan, C.; Störmer, M.; Toleikis, S.; Tschentscher, Th; Heimann, P. A.; Dorchies, F.

2014-04-01

The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called ``molecular movie'' within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.

Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

PubMed Central

Gaudin, J.; Fourment, C.; Cho, B. I.; Engelhorn, K.; Galtier, E.; Harmand, M.; Leguay, P. M.; Lee, H. J.; Nagler, B.; Nakatsutsumi, M.; Ozkan, C.; Störmer, M.; Toleikis, S.; Tschentscher, Th; Heimann, P. A.; Dorchies, F.

2014-01-01

The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called “molecular movie” within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level of the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes. PMID:24740172

Resonant Doppler velocimeter. Ph.D. Thesis. Final Report, 1 Jul. 1974 - 31 Oct. 1979; [velocity, temperature, and pressure measurement

NASA Technical Reports Server (NTRS)

Zimmermann, M.

1980-01-01

A technique is presented for visualizing and quantitatively measuring velocity, temperature, and pressure by shining a single frequency laser beam into a gaseous flow which is seeded with an atomic species. The laser is tuned through the absorption frequencies of the seeded species and the absorption profile is detected by observing fluorescence as the atoms relax back to the ground state. The flow velocity is determined by observing the Doppler shift in the absorption frequency. Spectroscopic absorption line broadening mechanisms furnish information regarding the static temperature and pressure of the moving gas. Results of experiments conducted in the free stream and in the bow shock of a conical model mounted in a hypersonic wind tunnel indicate that the experimental uncertainties in the measurement of average values for the velocity, temperature and pressure of the flow are 0.1, 5 and 10 percent respectively.

Towards simultaneous measurements of electronic and structural properties in ultra-fast x-ray free electron laser absorption spectroscopy experiments

DOE PAGES

Gaudin, J.; Fourment, C.; Cho, B. I.; ...

2014-04-17

The rapidly growing ultrafast science with X-ray lasers unveils atomic scale processes with unprecedented time resolution bringing the so called “molecular movie” within reach. X-ray absorption spectroscopy is one of the most powerful x-ray techniques providing both local atomic order and electronic structure when coupled with ad-hoc theory. Collecting absorption spectra within few x-ray pulses is possible only in a dispersive setup. We demonstrate ultrafast time-resolved measurements of the LIII-edge x-ray absorption near-edge spectra of irreversibly laser excited Molybdenum using an average of only few x-ray pulses with a signal to noise ratio limited only by the saturation level ofmore » the detector. The simplicity of the experimental set-up makes this technique versatile and applicable for a wide range of pump-probe experiments, particularly in the case of non-reversible processes.« less

Comparison of femtosecond- and nanosecond-two-photon-absorption laser-induced fluorescence (TALIF) of atomic oxygen in atmospheric-pressure plasmas

NASA Astrophysics Data System (ADS)

Schmidt, Jacob B.; Sands, Brian; Scofield, James; Gord, James R.; Roy, Sukesh

2017-05-01

Absolute number densities of atomic species produced by nanosecond (ns)-duration, repetitively pulsed electric discharges are measured by two-photon-absorption laser-induced fluorescence (TALIF). Unique to this work is the development of femtosecond-laser-based TALIF (fs-TALIF) that offers a number of advantages over more conventional nanosecond (ns)-pulse-duration laser techniques, such as higher-fidelity quenching rate measurements over a wide pressure range, significantly reduced photolytic interference (including photo-dissociation and photo-ionization), ability to collect two-dimensional images of atomic-species number densities with high spatial resolution aided by higher signal level, and efficient and accurate measurements of atomic-species number densities due to the higher repetition rates of the laser. For full quantification of these advantages, atomic-oxygen TALIF signals are collected from an atmospheric-pressure plasma jet employing both ns- and fs-duration laser-excitation pulses and the results are compared and contrasted.

Atomic Data Revisions for Transitions Relevant to Observations of Interstellar, Circumgalactic, and Intergalactic Matter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cashman, Frances H.; Kulkarni, Varsha P.; Kisielius, Romas

2017-05-01

Measurements of element abundances in galaxies from astrophysical spectroscopy depend sensitively on the atomic data used. With the goal of making the latest atomic data accessible to the community, we present a compilation of selected atomic data for resonant absorption lines at wavelengths longward of 911.753 Å (the H i Lyman limit), for key heavy elements (heavier than atomic number 5) of astrophysical interest. In particular, we focus on the transitions of those ions that have been observed in the Milky Way interstellar medium (ISM), the circumgalactic medium (CGM) of the Milky Way and/or other galaxies, and the intergalactic mediummore » (IGM). We provide wavelengths, oscillator strengths, associated accuracy grades, and references to the oscillator strength determinations. We also attempt to compare and assess the recent oscillator strength determinations. For about 22% of the lines that have updated oscillator strength values, the differences between the former values and the updated ones are ≳0.1 dex. Our compilation will be a useful resource for absorption line studies of the ISM, as well as studies of the CGM and IGM traced by sight lines to quasars and gamma-ray bursts. Studies (including those enabled by future generations of extremely large telescopes) of absorption by galaxies against the light of background galaxies will also benefit from our compilation.« less

Limestone-based technosols: a suitable way for the remediation of sediments contaminated by heavy metals.

NASA Astrophysics Data System (ADS)

Martínez-Sanchez, Maria Jose; Garcia-Lorenzo, Mari Luz; Martínez, Salvadora; Gonzalez, Eva; Molina, Jose; Hernández, Carmen; Pérez-Sirvent, Carmen

2013-04-01

The aim of this work was to assess the suitability of limestone-based technosols for decreasing the toxicity of the leachates caused by rain in sites contaminated by heavy metals. For such a purpose, 64 technosols were prepared in containers of 0.75m3, filled with 4 types of sediments collected from Portman Bay and subjected to different stabilizer proportions (limestone filler), different thickness of a drainage layer and presence/absence of a topsoil cover. The technosols were then submitted to different humidity/dryness cycles simulating the usual rain conditions in the zone. Portman bay is situated close to the mining region of La Unión. The entire area around the bay was subject to mining from the time of the Roman Empire to 1991. Since 1957, the wastes from mining operations were discharged directly into the sea in the inner part of the bay, while later on, they were also discharged to sea at a distance of the shore. These wastes mainly consisted in ore materials (galena, pyrite and sphalerite), phyllosilicates, in addition to siderite, iron oxides and sometimes alteration products such as jarosite, alunite, kaolinite and greenalite. These materials have suffered a concentration process by floatation with sea water and as a result of the discharge, the whole of the bay has filled up with wastes which also extend into the Mediterranean Sea. The pH and the electrical conductivity (EC) was determined in obtained percolates, together with major ion content, determined by ionic chromatography. The Zn, Pb, Cd and Cu content was determined by electrothermal atomization atomic absorption spectrometry (ETAAS). The As content was measured by atomic fluorescence spectrometry. In addition, the mineralogical composition was determined in the evaporated samples by X-Ray diffraction. A battery of bioassays was applied for the ecotoxicological screening of obtained percolates . Particularly, the toxicity was evaluated by using three assays: microtox bioassay (Vibrio fischeri), embryogenesis assay in sea urchin (Paracentrotus lividus) and survival in estuarine amphipods (Gammarus aequicauda). The obtained results suggest that selected remediation technique reduces significantly the toxicological effect of the percolate to the tested organisms. The ecotoxicological testing may be a useful approach for assessing the toxicity as a complement to chemical analysis. In addition, the use of a battery of bioassays allows diminishing problems related to false positive results. The use of limestone filler constitutes an excellent option in sediments polluted by trace elements, because of risk for human health or ecosystems does not exist after the intervention. in addition, the designed experience allow to optimize stabilizer quantities, and may suppose a big cost-saving project in areas affected by mining activities.

Atomic-Layer-Confined Doping for Atomic-Level Insights into Visible-Light Water Splitting.

PubMed

Lei, Fengcai; Zhang, Lei; Sun, Yongfu; Liang, Liang; Liu, Katong; Xu, Jiaqi; Zhang, Qun; Pan, Bicai; Luo, Yi; Xie, Yi

2015-08-03

A model of doping confined in atomic layers is proposed for atomic-level insights into the effect of doping on photocatalysis. Co doping confined in three atomic layers of In2S3 was implemented with a lamellar hybrid intermediate strategy. Density functional calculations reveal that the introduction of Co ions brings about several new energy levels and increased density of states at the conduction band minimum, leading to sharply increased visible-light absorption and three times higher carrier concentration. Ultrafast transient absorption spectroscopy reveals that the electron transfer time of about 1.6 ps from the valence band to newly formed localized states is due to Co doping. The 25-fold increase in average recovery lifetime is believed to be responsible for the increased of electron-hole separation. The synthesized Co-doped In2S3 (three atomic layers) yield a photocurrent of 1.17 mA cm(-2) at 1.5 V vs. RHE, nearly 10 and 17 times higher than that of the perfect In2S3 (three atomic layers) and the bulk counterpart, respectively. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study of atomic coherence effects in multi-level V+Ξ system involving Rydberg state

NASA Astrophysics Data System (ADS)

Kaur, Amanjot; Singh, Neeraj; Kaur, Paramjit

2018-06-01

We present theoretical model to investigate the influence of hyperfine levels on the atomic coherences of V+Ξ Rydberg system. Using density matrix formulation, an analytical expression of atomic coherence for weak probe field is derived. The closely spaced hyperfine levels cause asymmetry and red shift while wavelength mismatching induced due to Rydberg state leads to reduction in magnitude and broadening of group index, absorption and dispersion profiles for moving atoms. Our system shows both Rydberg Electromagnetically induced transparency (EIT) with subluminal behavior and Rydberg Electromagnetically induced absorption (EIA) with superluminal propagation by adjusting the strengths of control and switching fields. Variation of group index with probe detuning reveals anomalous dispersion regions at Autler-Townes doublet positions. Group index for Doppler-broadened atoms at resonance condition has lower magnitude as compared to the stationary atoms and hence the group delay time of the pulse is also reduced. We also explore in-depth non-degenerate four-wave mixing (FWM) which is ignited due to the presence of three electromagnetic (e.m.) fields and concurrently, establish relationship between FWM and multi-photon atomic coherence. The transient behavior is also studied for practical realization of our considered system as optical switch.

Evaluation of mesoporous silicon thermal conductivity by electrothermal finite element simulation

PubMed Central

2012-01-01

The aim of this work is to determine the thermal conductivity of mesoporous silicon (PoSi) by fitting the experimental results with simulated ones. The electrothermal response (resistance versus applied current) of differently designed test lines integrated onto PoSi/silicon substrates and the bulk were compared to the simulations. The PoSi thermal conductivity was the single parameter used to fit the experimental results. The obtained thermal conductivity values were compared with those determined from Raman scattering measurements, and a good agreement between both methods was found. This methodology can be used to easily determine the thermal conductivity value for various porous silicon morphologies. PMID:22849851

Experimental observation of the stratified electrothermal instability on aluminum with thickness greater than a skin depth

NASA Astrophysics Data System (ADS)

Hutchinson, T. M.; Awe, T. J.; Bauer, B. S.; Yates, K. C.; Yu, E. P.; Yelton, W. G.; Fuelling, S.

2018-05-01

A direct observation of the stratified electrothermal instability on the surface of thick metal is reported. Aluminum rods coated with 70 μ m Parylene-N were driven to 1 MA in 100 ns , with the metal thicker than the skin depth. The dielectric coating suppressed plasma formation, enabling persistent observation of discrete azimuthally correlated stratified thermal perturbations perpendicular to the current whose wave numbers, k , grew exponentially with rate γ (k ) =0.06 n s-1-(0.4 n s-1μ m2ra d-2 ) k2 in ˜1 g /c m3 , ˜7000 K aluminum.

Electrothermal actuation based on carbon nanotube network in silicone elastomer

NASA Astrophysics Data System (ADS)

Chen, L. Z.; Liu, C. H.; Hu, C. H.; Fan, S. S.

2008-06-01

The authors report an electrothermal actuator, which is fabricated by involving carbon nanotube network into the silicone elastomer. The actuators exhibit excellent performances as good as normal dielectric elastomer actuators while working under much lower voltages (e.g., 1.5Vmm-1). They are longitudinal actuators and there is no need for stacking or rolling sheets of materials. In addition, they can satisfy the demand of different voltage applications ranging from dozens of voltages to thousands of voltages by using different carbon nanotube loading composites. Visible maximal strain of 4.4% occurs at an electric power intensity around 0.03Wmm-3.

An improved electrothermal model for the ERBE nonscanning radiometer - Comparison of predicted and measured behavior during solar observations

NASA Technical Reports Server (NTRS)

Tira, Nour E.; Mahan, J. R.; Lee, Robert B., III

1989-01-01

The improved Earth Radiation Budget Experiment nonscanning-channels electrothermal model presented is used to model two types of solar observations: those obtained through the solar port during solar calibration, and and those obtained during the satellite pitch-over maneuver, in which the sun is observed by the radiometer while it is in earth-viewing configuration. Thermal noise has been separately studied to evaluate its contribution to the radiative energy absorbed by the active cavity. It is found that the scattering of the collimated solar radiation contributes an average of 0.071 mW during solar calibration.

Primary propulsion of electrothermal, ion, and chemical systems for space-based radar orbit transfer

NASA Technical Reports Server (NTRS)

Wang, S.-Y.; Staiger, P. J.

1985-01-01

An orbit transfer mission concept has been studied for a Space-Based Radar (SBR) where 40 kW required for radar operation is assumed available for orbit transfer propulsion. Arcjet, pulsed electrothermal (PET), ion, and storable chemical systems are considered for the primary propulsion. Transferring two SBR per shuttle flight to 1112 km/60 deg using eiectrical propulsion systems offers an increased payload at the expense of increased trip time, up to 2000 kg each, which may be critical for survivability. Trade offs between payload mass, transfer time, launch site, inclination, and height of parking orbits are presented.

Experimental Observation of the Stratified Electrothermal Instability on Aluminum with Thickness Greater than a Skin Depth

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hutchinson, Trevor M.; Hutchinson, Trevor M.; Awe, Thomas James

The first direct observation of the stratified electrothermal instability on the surface of thick metal is reported. Aluminum rods coated with 70 μm Parylene-N were driven to 1 MA in approximately 100 ns, with the metal thicker than the skin depth. The dielectric coating suppressed plasma formation, enabling persistent observation of discrete azimuthally-correlated stratified structures perpendicular to the current. Strata amplitudes grow rapidly, while their Fourier spectrum shifts toward longer wavelength. Assuming blackbody emission, radiometric calculations indicate strata are temperature perturbations that grow exponentially with rate γ = 0.04 ns -1 in 3000- 10,000 K aluminum.

Ni-Mn-Ga shape memory nanoactuation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohl, M., E-mail: manfred.kohl@kit.edu; Schmitt, M.; Krevet, B.

2014-01-27

To probe finite size effects in ferromagnetic shape memory nanoactuators, double-beam structures with minimum dimensions down to 100 nm are designed, fabricated, and characterized in-situ in a scanning electron microscope with respect to their coupled thermo-elastic and electro-thermal properties. Electrical resistance and mechanical beam bending tests demonstrate a reversible thermal shape memory effect down to 100 nm. Electro-thermal actuation involves large temperature gradients along the nanobeam in the order of 100 K/μm. We discuss the influence of surface and twin boundary energies and explain why free-standing nanoactuators behave differently compared to constrained geometries like films and nanocrystalline shape memory alloys.

Ni-Mn-Ga shape memory nanoactuation

NASA Astrophysics Data System (ADS)

Kohl, M.; Schmitt, M.; Backen, A.; Schultz, L.; Krevet, B.; Fähler, S.

2014-01-01

To probe finite size effects in ferromagnetic shape memory nanoactuators, double-beam structures with minimum dimensions down to 100 nm are designed, fabricated, and characterized in-situ in a scanning electron microscope with respect to their coupled thermo-elastic and electro-thermal properties. Electrical resistance and mechanical beam bending tests demonstrate a reversible thermal shape memory effect down to 100 nm. Electro-thermal actuation involves large temperature gradients along the nanobeam in the order of 100 K/μm. We discuss the influence of surface and twin boundary energies and explain why free-standing nanoactuators behave differently compared to constrained geometries like films and nanocrystalline shape memory alloys.

Evaluation of candidate working fluid formulations for the electrothermal - chemical wind tunnel

NASA Technical Reports Server (NTRS)

Akyurtlu, Jale F.; Akyurtlu, Ates

1991-01-01

Various candidate chemical formulations are evaluated as a precursor for the working fluid to be used in the electrothermal hypersonic test facility which was under study at the NASA LaRC Hypersonic Propulsion Branch, and the formulations which would most closely satisfy the goals set for the test facility are identified. Out of the four tasks specified in the original proposal, the first two, literature survey and collection of kinetic data, are almost completed. The third task, work on a mathematical model of the ET wind tunnel operation, was started and concentrated on the expansion in the nozzle with finite rate kinetics.

Primary propulsion of electrothermal, ion and chemical systems for space-based radar orbit transfer

NASA Technical Reports Server (NTRS)

Wang, S. Y.; Staiger, P. J.

1985-01-01

An orbit transfer mission concept has been studied for a Space-Based Radar (SBR) where 40 kW required for radar operation is assumed available for orbit transfer propulsion. Arcjet, pulsed electrothermal (PET), ion, and storable chemical systems are considered for the primary propulsion. Transferring two SBR per shuttle flight to 1112 km/60 deg using electrical propulsion systems offers an increased payload at the expense of increased trip time, up to 2000 kg each, which may be critical for survivability. Trade offs between payload mass, transfer time, launch site, inclination, and height of parking orbits are presented.

Ultrathin phase-change coatings on metals for electrothermally tunable colors

NASA Astrophysics Data System (ADS)

Bakan, Gokhan; Ayas, Sencer; Saidzoda, Tohir; Celebi, Kemal; Dana, Aykutlu

2016-08-01

Metal surfaces coated with ultrathin lossy dielectrics enable color generation through strong interferences in the visible spectrum. Using a phase-change thin film as the coating layer offers tuning the generated color by crystallization or re-amorphization. Here, we study the optical response of surfaces consisting of thin (5-40 nm) phase-changing Ge2Sb2Te5 (GST) films on metal, primarily Al, layers. A color scale ranging from yellow to red to blue that is obtained using different thicknesses of as-deposited amorphous GST layers turns dim gray upon annealing-induced crystallization of the GST. Moreover, when a relatively thick (>100 nm) and lossless dielectric film is introduced between the GST and Al layers, optical cavity modes are observed, offering a rich color gamut at the expense of the angle independent optical response. Finally, a color pixel structure is proposed for ultrahigh resolution (pixel size: 5 × 5 μm2), non-volatile displays, where the metal layer acting like a mirror is used as a heater element. The electrothermal simulations of such a pixel structure suggest that crystallization and re-amorphization of the GST layer using electrical pulses are possible for electrothermal color tuning.